Tesis: "Overheating"

1

Gichuyia, Linda Nkatha. "Indoor overheating risk : a framework for temporal building adaptation decision-making". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/270294.

Texto completo

Resumen

Overheating in buildings is predicted to increase as a result of a warming climate and urbanisation in most cities. With regards to responding to this challenge, decision makers ranging from_ design teams, local authorities, building users, national programs and market innovators; and during the different stages of a building’s service life, want to know a few pertinent matters: What space characteristics and buildings are at a higher risk and by how much?; What are the tradeoffs between alternative design and/or user-based actions?; What are the likely or possible consequences of their decisions?; What is the impact of climate change to indoor overheating?; among other decision support questions. However, such decision appraisal information still remains buried and dispersed in existing simulation models, and empirical studies, and not yet been clearly articulated in any existing study or model. Especially decision support information articulated in a way that gives each decision maker maximum capacity to anticipate and respond to thermal discomfort in different spaces and through the lifetime of a building. There is a need for an integrated and systematic means of building adaptation decision-support, which provides analytical leverage to these listed decision makers. A means that: 1) assimilates a range of indoor thermal comfort's causal and solution space processes; 2) reveals and enhances the exploration of the space and time-dependent patterns created by the dynamics of the indoor overheating phenomenon through time; and one that 3) imparts insight into decision strategy and its synthesis across multiple decision makers. This study recognises the lack of an overarching framework attending to the listed concerns. Therefore, the key aim of this thesis is to develop and test a building adaptation decision-support framework, which extends the scope of existing frameworks and indoor overheating risk models to facilitate trans-sectional evaluations that reveal temporal decision strategies. The generic framework frames a multi-method analysis aiming to underpin decision appraisal for different spaces over a 50 to 100-year time horizon. It constitutes an underlying architecture that engages the dimensions of decision support information generation, information structuring, its exploration and dissemination, to ease in drawing decision strategy flexibly and transparently. The multi-method framework brings together: 1) Systems thinking methods to a) facilitate the systematic exposure of the elements that shape indoor overheating risk, and b) reveal the processes that shape multi-stakeholder decision-making response over time; 2) The use of normative, predictive and exploratory building scenarios to a) examine the overheating phenomenon over time, and b) as a lens through which to explore the micro-dynamics brought about by aspects of heterogeneity and uncertainty; and 3) The application of both computational and optimization techniques to appraise potential routes towards indoor thermal comfort over an extended time scale by a) tracking shifts in frequency, intensity and distribution of indoor overheating vulnerability by causal elements over time and space; and b) tracking shifting optima of the heat mitigation solution space, with respect to time, climate futures, heterogeneity of spaces, and due to thermal comfort assumptions. The framework’s potential has been demonstrated through its application to office buildings in Nairobi.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Montazami, Azadeh. "Aircraft noise, overheating and poor air quality in London primary schools' classrooms". Thesis, London Metropolitan University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555145.

Texto completo

Resumen

Providing a comfortable environment is the fundamental aim in Architecture. Comfortable environment mainly refers to a surrounding atmosphere which is thermally, acoustically, visually, aesthetically, etc. comfortable. Generally, environmental comfort is assessed by environmental factors such as thermal, acoustic and lighting comfort as well as air quality. There is a significant relationship between various environmental factors and students' academic achievements as well as health. Providing all of the environmental factors together is critical as they are interrelated and could conflict if they are considered separately, if the conditions over the life of the building change or relaxed benchmarks are used for design at the first stage. One of the conflicts reviewed in this study, is the conflict between acoustic comfort with thermal comfort and air quality. The hypothesis of this research is that the naturally ventilated schools located in noisy areas (e.g. Heathrow airport) suffer from overheating and poor air quality as well as a high level of background noise during summer periods, due to the lack of ventilation. The main means of ventilation in majority of the UK schools is window. In noisy areas, the classrooms' occupants (i.e. pupils, teachers) often tend to shut windows especially during silent (such as exams and readings) and lecturing activities to reduce the aircraft noise, which varies from 57dB-75dB according to their distances to Heathrow airport. On an average, as a result of closing windows, the aircraft noise drops by 15dB (depending on the type of windows) which makes the inside noise to be around 42dB-60dB. This is still higher than the 35dB which is the acceptable limit for background noise for primary school classrooms as recommended by Building Bulletin 93. The results of the study show that closing of windows does not reduce the high level of background noise to the recommended level, but it also has two negative impacts on classrooms' environments. Firstly it increases the potential for classrooms to experience overheating and secondly it causes poor air quality due to the lack of sufficient ventilation in the building. Through objective and subjective surveys, classrooms' indoor temperatures, air quality and background noise levels were evaluated and it was learnt that those schools located in the vicinity of Heathrow Airport are more likely to experience overheating and poor air quality. This has a negative impact on students' achievements. In addition, one of the reasons for the lack of environmental comfort is the use of relaxed benchmarks. It is shown in this study that overheating and air quality benchmarks which are proposed by 'Department for Education and Skills' in Building Bulletin 101 and used to design and refurbish the UK schools, are relaxed benchmarks in comparison with the others which are proposed by different organisations and researchers. The overall findings of this thesis have been developed to draw the attention of school designers' to the current and future potential conflicts between the comfort factors in schools' classrooms. To prevent failure, extra care should be taken to select a suitable ventilation strategy for providing both air quality and thermal comfort during summer for the schools located under the flights paths. For such schools, it would be beneficial that the solar gain and internal gain are controlled and heavy thermal mass materials are used for their construction. Such strategies would counterweigh the lack of ventilation in protecting the classrooms from overheating. It is also suggested that a further section is incorporated to the comfort section of the school design assessment tools to evaluate the current and future potential conflict between comfort issues in the schools' buildings. In addition, air quality and summer thermal comfort guidelines incorporated to BB 101 are recommended to be revised (similar to the acoustic section of this guideline which was revised to stringent benchmarks for background noise level and reverberation time and included in BB93).

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Sougkakis, Vasileios. "An investigation into the overheating risk in low-energy new-built homes". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39465/.

Texto completo

Resumen

Recently, overheating in British housing has received increased attention due to climate change and consequent impact on the thermal comfort and the health of building occupants. The risk of overheating becomes even larger considering the requirements for higher insulation and airtightness levels set by building regulations. Passive design strategies, such as the use of thermal mass and ventilation, for regulating indoor temperatures may improve the thermal comfort of occupants without the use of energy intensive equipment. Modern Methods of Construction (MMC) are expected to play a significant role in the future outputs of the housing construction sector. However, MMC, which generally present low levels of thermal mass, are treated with scepticism by designers since they are considered to be more prone to overheating compared to masonry constructions. Due to the lack of extensive research data on the thermal performance of these systems, however, it can be inferred that concerns may be based on the perception of the industry rather than actual data. Therefore, the work presented in this thesis investigated the risk of overheating in dwellings built with MMC. The analysis considered the performance of the constructions from various perspectives following a route from the general investigation to the more specific characteristics of the building elements. First, an investigation of the zone temperatures obtained through monitoring and through whole building dynamic simulations was performed, in an attempt to evaluate the relative performance of different construction types and building elements. Next, the interaction of the various building elements with their surrounding space was assessed through monitoring the heat flows and the temperatures on the surface of these elements in situ. Finally, a more detailed investigation of the dynamic characteristics of these elements under fixed conditions was conducted through laboratory testing and Finite Element Analysis (FEA). A parametric simulation study of ambient temperatures in a timber frame building considered the potential to use non-traditional materials for regulating internal temperatures. Results showed that overheating was an issue in most of the zones examined for the conventional timber frame construction. The use of additional materials resulted in reduced overheating levels of up to 85% in some cases; this evidence may be used to inform designers when considering measures to reduce the overheating risk of MMC. In another study of two houses built with different construction methods, it was found that the timber frame and modern masonry walls had very similar performance, with the latter presenting slightly reduced levels of overheating in some cases (up to 12% lower compared to timber frame). Monitoring the heat flows at the surface of the building elements in situ as well as through laboratory testing and FEA showed that difference in performance between masonry constructions and MMC was not always as clear as expected from the construction characteristics of the elements. It was clear that conventional masonry constructions do not benefit fully from the increased mass and had comparable performance with some MMC. Phase Change Materials (PCM) were also found more responsive than conventional plasterboard in situ, although some discrepancy compared to the theoretical performance was identified. The findings of this study may be useful for designers so that optimum use of the benefits of thermal mass is made.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Hernandez, Tascon Mauricio. "Experimental and computational evaluation of thermal performance and overheating in double skin facades". Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/10628/.

Texto completo

Resumen

Double Skin Facades (DSFs) have been developed as an alternative technology to improve the thermal performance of conventional fully glazed buildings. Nevertheless, there is little test information on the behaviour and real performance of DSFs. This is specifically the case when the facade has to perform under extreme or moderate summer conditions. The characteristics of thermal overheating of a specific type of DSF with various configurations and its practical control have not been subjected to systematic experimental and computational investigations. This research which is based on an existent load of knowledge, carried out experiments of a full-scale one-storey laboratory chamber of a selected type of Double Skin Facade in which a comparative analysis of the thermal performance is assessed, CFD simulations of the experimental model and a Field Case Study of an existing building in the United Kingdom is also monitored. The basic thermal behaviour in the facade cavity and adjacent room is investigated by a series of parametric studies and basic flow field investigations. Section models of the DSF chamber and the case building were made and modelled using CFD in order to visualise the thermal and airflow behaviour inside the DSF complementing the experimental and field work. The modelling work has demonstrated the feasibility and versatility of the technique for probing the flow and thermal behaviour of double skin facades. It was found that natural ventilation through the cavity by a series of controlled opening shafts on the upper and lower facade are effective means to reduce DSF overheating. It was also observed that the optical properties of cavity elements, cavity depth size, solar control and the basic operation of the facade are key issues to address in order to prevent overheating and additional heat loads from the facade.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Murphy, John T. "Overheating of low-allow forging steels for nuclear power plant rotors and vessels". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/37531.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Thomson, Susan C. "Why do bats fly at night? : the role of hyperthermia in constraining diurnal flight in bats". Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323141.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Curry, Heather Renee. "A Semiotic Phenomenology of Homelessness and the Precarious Community: A Matter of Boundary". Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5672.

Texto completo

Resumen

My dissertation focuses on the articulation of the concepts of precarity —i.e., temporary, affective, creative, immaterial and insecure labor—and community in an overheating system. My site of inquiry is homelessness broadly, but more specifically the labor of panhandling and the identity of “the panhandler.” I recognize that primary theorizations of precarity have located it as a problem of labor and economy. Others have looked at it from the sociological domain. My work looks at precarity as diffuse across social, political, and communal systems, but primarily as an effect of the problem of overheating as it manifests at varying levels of scale. Narrowing the global vision of such instability and insecurity to a local landscape—to streets, corners, traffic, the people who occupy infrastructural liminal zones and whose lives are precariously bound to the forces of speed and heat—reveals the critical nature of elemental metaphors. That is to say, if we might accept the thesis that we are in an epoch in which speed and time subsumes space and place, and if speed is another way of talking about heat, about intensities, then communication in the over-sped, overheated system is in dire straights. Precarity, I argue, is not causally linked to the breakdown in economy or the breakdown in affiliative bonds or networks—it does not precede or presage these shutdowns. Rather it is the shutdown. Precarity may now be viewed as the management and organization of social, political, affective, and communal bonds around economic and affiliative insecurities. I use ethnographic data from institutional meetings, and conversations with the key stakeholders at varying levels of scale, as well as textual analyses of local policies, news coverage, and public responses to those texts in order to understand how precarious communicative conditions affect the structuration of community and politics.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Reiter, Christoph Nikolaus. "Polymeric solar-thermal flat-plate collectors". Thesis, De Montfort University, 2014. http://hdl.handle.net/2086/10755.

Texto completo

Resumen

State-of-the-art solar-thermal flat-plate collectors suffer from a limited potential to decrease production costs for the necessary higher economic benefit of so-lar-thermal systems. Costly metallic materials and corresponding manufactur-ing processes prevent further cost reductions. For that issues, plastic materials can offer a promising approach. The main hurdle for the use of cost-effective plastics lies in the high thermal loads on the collector components — absorber and insulation — which were identified in a field-testing. The necessary overheating protection approaches to lower these thermal loads were investigated in a literature review. A large number of relevant concepts was evaluated related to achievable temperature reduction, influence on solar yield, additional costs and intrinsic safety. There-fore, a mathematical model was developed to determine the solar-thermal col-lector´s behaviour in a solar-thermal system for hot water and space heating. This way, the most promising overheating concepts were simulated and ana-lysed with regard to component temperatures and system performance. Omitting the selective absorber coating and reducing the backside insulation was found to be the most suitable solution for component materials with limited temperature resistance like polypropylene. In the second part of the research, collector design concepts were developed on the basis of the characteristics of plastic material processing. The identified unit costs showed savings of more than 50 % in comparison to stateof- the-art collectors. The analysis regarding temperature loads and annual solar yield by simulation proved the performance of the concepts. The collector costs and the simulation results were used to define the total costs of the solar-thermal sys-tems and to evaluate the economic benefits by means of the collector con-cepts. The benefits were similar to state-of-the-art set-ups. Thus, further adjustments at system level are necessary to lower the total costs. Therefore, the system set-up has to be harmonised with the collector requirements and investigated in detail.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Khalifa, Moataz. "Application of phase change materials as a solution for building overheating : a case for the UK". Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13837/.

Texto completo

Resumen

In the UK, there are about 26 million houses and the government’s future plan is to build 3 million more by 2020 (BBC, 2008, Jason, 2011). As the demand for housing increases, especially for single occupant homes, the rate of energy consumption and, in effect, the proportion of CO2 emissions is on the rise. Successful sustainable energy strategies for domestic buildings can thus be an effective tool for mitigating these effects and achieving healthy building conditions. The main aim of the research are obtaining comfortable building spaces by reducing any overheating and reduce energy demand by using passive method which also will reduce the emission of CO2. Also this work aims to raise attention on the influence of the domestic sector on the amount of CO2 emissions by using low thermal mass construction. Thus, the research’s objectives are divided into firstly, investigate the opportunity of improving the Micronal Phase Change Material (MPCM) thermal conductivity and secondly, studying the influence of using enhanced MPCM for reducing overheating in lightweight building construction. This research investigates means of improving the thermal performance of the UKs existing and new domestic buildings stock. In order to increase thermal resistance and hence reduce heat losses, a new panel comprised of outer coating and thin layer or aerogel to increase thermal resistance was developed which could be added to the exterior walls of existing houses. This research results have shown from the experimental work when MPCM coupled with construction materials that the percentage of MPCM should not be above 50% otherwise it will reduce the potential benefit of the mixture to enhance thermal conductivity of MPCM. The best thermal conductivity was obtained by mixing 20% PCM, 75% Gypsum and 5% Silica with honeycomb, which gave a value of 0.306 W/mK. On the other hand, the best thermal conductivity was obtained using the clay by mixing 40% MPCM, 20% Clay and 40% cement, which gave a value of 0.253 W/mK. The simulation results shown that natural night ventilation could help reduce the overheating period to about 50% with the use of MPCM. Finally, The results of the new external wall panel that has been developed to improve the thermal performance have shown that through application of these panels a substantial reduction between 3 ºC to 5 ºC in the internal temperature.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Kessentini, Hamdi. "Numerical and experimental study of a flat plate collector with honeycomb transparent insulation and overheating protection system". Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/144658.

Texto completo

Resumen

In this thesis a flat plate collector (FPC) with plastic transparent insulation materials (TIM) and a low-cost overheating protection system destined for heat supply from 80 to 120°C is presented. A ventilation channel with a thermally actuated door is inserted below the absorber allowing to protect the collector from stagnation conditions, while preserving good performance during normal operation. For this objective, a prototype has been constructed and experimentally tested and in parallel, numerical and CFD models have been implemented with the aim of predicting the thermal behavior of this collector. The present thesis consists of six chapters and a brief summary of each one is given below: In the first chapter, a literature survey is carried out in order to present the most updated R&D status in the field of solar heat at medium temperatures. This literature research has allowed to appreciate the latest findings and key challenges related to the studied topic and to present the contribution of this work to the pool of existing knowledge. The second chapter is devoted to the description of the experimental set up. The problem of overheating for FPC with TIM is first pointed out and the technical description of the studied FPC is then presented. The different sensors used and the test procedures adopted during the experiments are presented. In the third chapter, a fast calculation numerical model is implemented. This model is based on the resolution of the different components of the collector by means of a modular object-oriented platform. Indoor and outdoor tests are performed and have shown the effectiveness of the overheating system being able to maintain low enough temperatures at the collector preventing thus the plastic TIM from stagnation conditions. The comparison of the numerical results with experiments has demonstrated that the code can accurately reproduce the performance of the collector. Several parametric simulations are then performed in order to optimize the collector design: 3125 different configurations are evaluated by means of virtual prototyping and the results have allowed to propose the most promising design of a stagnation proof FPC with plastic TIM able to work at operating temperature 100°C with promising efficiency. In the forth chapter, the most critical elements of the collector (ventilation channel and air gap&TIM) have been substituted by high-level CFD objects in the implemented modular object-oriented code. For the detailed numerical simulations, Large Eddy Simulations (LES) modeling is used. In order to speed-up the simulations, parallelisation techniques are used. The numerical solutions are firstly validated with benchmark cases. Then, the general model of the collector is validated by comparison of the numerical results with the indoor experimental tests showing a reasonable agreement. The preliminary CFD simulation results have allowed to understand the heat transfer and fluid flow at different operating temperatures of the studied collector. In the fifth chapter, a heat transfer analysis of the honeycomb TIM is carried out. The combined radiation and conduction heat transfer across the isolated cell is treated by means of the solution of the energy equation in its three dimensional form which is coupled to the Radiative Transfer Equation (RTE). The Finite Volume Method is used for the resolution of the RTE. The numerical results are compared to experimental measurements of the heat transfer coefficient on various honeycomb TIM given by different authors in the literature showing acceptable agreements. Finally, a parametric study is conducted in order to investigate the effect of the variation of the most relevant optical and dimensional parameters of the TIM on the heat transfer. Finally, the last chapter summarizes the contribution of this thesis and discuss the possible directions of future research.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Lavaf, Pour Y. "Self-shading façade geometries to control summer overheating in UK Passivhaus dwellings for current and future climate scenarios". Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3009183/.

Texto completo

Resumen

The German Passivhaus building standard, with its emphasis on airtightness and very high levels of insulation, has become well known. It is widely applied to produce buildings that have a very low heating energy demand in winter whilst providing thermal comfort. However, there have been, over the last decade, instances of summertime overheating in Passivhaus buildings. Research has shown that the high internal air temperatures during summer in Passivhaus dwellings are mainly due to excessive solar gain through large south-facing glazing and a lack of natural ventilation. A number of well-established passive adaptation measures have received a great deal of research attention, and several have been implemented in to Passivhaus designs to reduce summer discomfort. Some of these approaches, such as window opening and blinds, are user-dependent, while other interventions, such as overhangs, are truly passive and do not require the occupants’ attention. Although thermal mass is not a user-dependent intervention, it typically works in conjunction with night purge ventilation, which is controlled by building users. The research presented here investigated a less examined passive approach to reducing overheating - the potential implementation of the envelope shape as an environmental design strategy to self-shade. This approach is architectural in nature, and so could have both aesthetic and environmental consequences. The research tested if altering the geometric form of a UK Passivhaus (by tilting the south facade to give self-shading) might be capable of passively protecting the house from the excessive solar gain in summer, both for current and future climate scenarios. This study used probabilistic climate change scenarios from the UK Climate Change Projections to determine the overheating risk in an existing Passivhaus dwelling under a high emission 50-percentile scenario in London. Dynamic thermal simulation modelling software (DesignBuilder) was used to examine the impact of various inclinations of the south façade of the Passivhaus dwelling to make use of the self-shading that this form created. A sensitivity analysis of internal temperatures and thermal comfort conditions in the dwelling as a function of building facade inclination and prevailing climatic conditions was undertaken. The research found that implementing an optimum angle tilted façade would moderate indoor temperature variations between day and night in summer and could potentially act as an effective shading device and reduce overheating by a significant amount while still being practical for collecting solar gains in winter. The proposed inclined façade could eliminate the risk of overheating for current climates; however, it was found that using only the geometric considerations would not solely be fully capable of eradicating the risk of future thermal discomfort overheating, particularly for UK climate scenarios of the 2080s. The suggested tilted façade was then analysed alongside other conventional approaches, such as overhangs and reduced window to wall ratios, to compare their relative effectiveness in reducing overheating risk. Manipulating the tilt of the south facing façade will clearly have other impacts on, for instance, winter heating demand, daylighting and natural ventilation air flows, and these parameters have also been examined using the lighting and computational fluid dynamics CFD algorithms in DesignBuilder. The consequences of a slight tilt of the south façade on daylight levels and airflows through the dwelling were apparent but not overly large. The research noted a concurrent increase in the heating demand and artificial lighting, but it was concluded that this increase was an acceptable trade-off compared to the reduced summer overheating risk.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Hill, Jorik [Verfasser], Michael [Gutachter] Bartke y Reinhard [Gutachter] Schomäcker. "Kinetics and catalyst overheating in the gas phase polymerization of propylene / Jorik Hill ; Gutachter: Michael Bartke, Reinhard Schomäcker". Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2021. http://d-nb.info/1237685818/34.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Porritt, Stephen Michael. "Adapting UK dwellings for heat waves". Thesis, De Montfort University, 2012. http://hdl.handle.net/2086/6327.

Texto completo

Resumen

The emphasis for UK dwelling refurbishment to date has centred on reducing heating energy use. However, there has been increasing evidence pointing to the need for a more holistic approach. Many existing dwellings already experience overheating during hot weather periods. Climate change projections predict increases in both the frequency and severity of extreme weather events including heat waves such as the one in August 2003, which is estimated to have claimed the lives of over 35,000 people throughout Europe, including 2,000 in the UK. Demand for housing exceeds the supply of new stock and it is estimated that over 70% of the dwellings that will be in use in 2050 have already been built. Therefore existing dwellings will require adaptation to provide more comfortable and safe environments, to reduce both summertime overheating and heating energy use. In this research, dynamic thermal simulation computer modelling was used to assess and rank the effectiveness of selected single and combined passive interventions (adaptations) on dwelling overheating during a heat wave period. Simulations were also carried out to assess the effect of those interventions on annual space heating energy use. Four distinct dwelling types were selected to represent the housing stock in London and South East England, producing seven modelling variants: 19th century end and mid-terraced houses; 1930s semi-detached house; 1960s ground, mid and top floor flats and a modern detached house. Simulations were carried out for two different occupancy profiles and four building orientations and the cost of interventions was also considered in the analysis. The first occupancy profile assumed a ‘typical’ family who left the dwellings unoccupied during the daytime, the second assumed residents who were at home all the time (e.g. elderly or infirm). Of the dwelling types studied the 1960s mid and top floor flats and the modern (2006) detached house (Tier 2) experienced more than twice as much overheating as the other dwelling types (Tier 1). Tier 2 dwellings were “harder to treat” and unlike Tier 1 dwellings their overheating exposure could not be eliminated using the selected passive interventions. It was possible to substantially reduce overheating and annual heating energy use of Tier 1 dwellings at moderate cost, whereas the costs for retrofitting Tier 2 dwellings were estimated to be many times higher. The results demonstrated that overheating exposure can be significantly greater for residents who have to stay at home during the daytime and they should not, where possible, be housed in the most vulnerable dwellings. External window shutters were found to be the single most effective intervention for overheating reduction in most of the dwelling types considered, typically resulting in a 50% reduction in overheating exposure. The exception was the 19th century terraced houses, where applying a solar reflective (high albedo) coating to the solid external walls was often more effective. In some cases the addition of insulation increased overheating and external wall insulation consistently outperformed internal wall insulation when considering the effect on overheating, though the latter could be effective as an element of combined interventions. Adaptation should therefore be considered together with mitigation, both in design practice and in regulations. If existing dwellings (for example the 19th century terraced houses) are retrofitted for energy efficiency, without considering summer use, overheating could increase dramatically. Subsequent corrective measures could be costly and energy efficiency may suffer as a result. This research builds on previous publications and research to generate systematic, quantitative and holistic guidance for retrofitting UK dwellings to reduce overheating risk during heat waves, whilst minimising annual space heating energy use and considering the cost of retrofit. An interactive retrofit advice toolkit has been developed (and made publicly available) as part of the research, which allows selection of the best performing interventions within a given budget. Recommendations for further development of the research are also suggested.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Fifield, Louis-James. "Monitoring UK hospital building type performance". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24623.

Texto completo

Resumen

The British National Health Service (NHS) is one of the largest public services in the world and consequentially in 2004 it produced 25% of the total public sector carbon emissions for England. To meet national carbon targets the NHS must reduce its emissions; 26% by 2020, 64% by 2030, 80% by 2050 and is therefore interested in the development of strategies for reducing carbon dioxide emissions from buildings. The NHS building stock consists of a range of building archetypes constructed over the past 100 years. The energy used for heating and cooling hospital premises is the source of 22% of all NHS carbon emissions. The individual buildings are distributed across hospital sites that often have centralised energy plants, which make it difficult to monitor energy consumption on an individual building level. This thesis develops a method for monitoring the energy consumption of individual hospital buildings. The method was implemented on three case study buildings at Bradford Royal infirmary (BRI); a 1920s Nightingale, a nucleus and a modern modular building. Lessons were gathered from these studies to advance the knowledge on monitoring in UK hospitals. One of the key findings was that empirical models based on measured data are useful for estimating individual buildings annual heating energy consumption. The results show that the mechanically ventilated nucleus building had the highest energy consumption (808.7kWh/m2), followed by the naturally ventilated Nightingale building (420.7kWh/m2) and then the mixed-mode modular building (289.0kWh/m2). The internal environment was optimal in the nucleus building, but the Nightingale and modular buildings underperformed, with the modular overheating in summer and both buildings failing to meet air quality recommendations. Taking energy consumption and summer thermal resilience into consideration the Nightingale building had the best performance, demonstrating the longevity of the traditional design. The work identified a number of useful hospital design features; well-insulated heavyweight building fabric, well-controlled space heating, use of heat recovery ventilation and installation of localised monitoring equipment. Further useful research into this area could involve: using dynamic thermal simulation to test recommended building design features, investigating the monitoring method on a wider sample of sites and investigating air quality monitoring in hospitals.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Liu, Chunde. "Creation of hot summer years and evaluation of overheating risk at a high spatial resolution under a changing climate". Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.725405.

Texto completo

Resumen

It is believed that the extremely hot European summer in 2003, where tens of thousands died in buildings, will become the norm by the 2040s, and hence there is the urgent need to accurately assess the risk that buildings pose. Thermal simulations based on warmer than typical years will be key to this. Unfortunately, the existing warmer than typical years, such as probabilistic Design Summer Years (pDSYs) are not robust measures due to their simple selection method, and can even be cooler than typical years. This study developed two new summer reference years: one (pHSY-1) is suitable for assessing the occurrence and severity of overheating while the other (pHSY-2) is appropriate for evaluating the thermal stress. Both have been proven to be more robust than the pDSYs. In addition, this study investigated the spatial variation in overheating driven by variability in building characteristics and the local environment. This variation had been ignored by previous studies, as most of them either created thermal models using building archetypes with little or no concern about the influence of local shading, or assumed little variation in climate across a landscape. For the first time, approximately a thousand more accurate thermal models were created for a UK city based on the remote measurement including building characteristics and their local shading. By producing overheating and mortality maps this study found that spatial variation in the risk of overheating was considerably higher due to the variability of vernacular forms, contexts and climates than previously thought, and that the heat-related mortality will be tripled by the 2050s if no building and human thermal adaptations are taken. Such maps would be useful to Governments when making cost-effective adaptation strategies against a warming climate.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Basson, Nicol. "Studying water-wedging as a cause for short term overheating in the boiler of a coal-fired power plant". Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29585.

Texto completo

Resumen

A common failure occurrence on fossil fuel power plant boiler systems is referred to as short term overheating (STO). This phenomenon occurs when the tube is heated to higher than its design temperature in a short period of time, causing a ductile failure of the tube material. The superheaters are particularly susceptible to STO. Such a failure can be caused by various conditions, where most of these are condition-based, i.e. based on the physical condition of the pipes or boiler. However, there are some cases which are process-related, i.e. based on the thermo-physical process occurring inside the pipe. Very often a water blockage or water wedge is recorded to be the root cause of the short term overheating in superheaters when no condition-based indicators can be found. It then is claimed to be the result of over-attemperation spray by the operator. This type of failure tends to happen at the outlet of vertical (pendant-type) superheaters. This study aims to find thermo-physical conditions where such a conclusion is valid by studying the transient behaviour of a representative superheater segment under postulated conditions. The specific geometry chosen is one for which short term overheating due to water wedging has been recorded in the past. A transient flow model was constructed and verified by comparing its results with plant data, as well as some results from a numerical model developed from fundamental principles. Once the simulation modelling methodology was confirmed, the model was modified to resemble the geometry of the final superheater outlet leg to facilitate direct comparison with a pendant boiler component as found on a power plant. A number of scenarios were executed in transient state on the model at different boiler loads. The temperature evolution of the pipe wall was tracked over time, and together with calculated equivalent stresses, was compared to the yield strength of the material. A temperature vs yield strength curve was obtained from material testing using new and aged tube material. The results showed that short term overheating at the superheater outlet tubes due to water blockages alone is unlikely to occur, even at low loads and substantial over firing. The stresses exerted over the tube wall and throughout the tube length is not enough to overcome the yield stress of the superheater tube material, even for aged material. Thus, the claim of overattemperation as the root cause of a short term overheating failure is improbable, and other explanations for the failure must be observed. Even though it is possible for water-wedging to occur, the phenomenon alone is unlikely to be the root cause for the occurrence of short term overheating.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

NERI, Manuela. "Experimental and numerical analysis of heat trasnfer at chimney-roof penetration in relation to the overheating of flammable materials". Doctoral thesis, Università degli studi di Brescia, 2016. https://hdl.handle.net/11379/569289.

Texto completo

Resumen

Chimneys convey exhaust gas produced in domestic heating appliances to the external ambient and to do this they have to pass through roofs and oors. The increasing attention to sustainability and energy saving has led to better insulated buildings, with roofs made up of combustible materials. From the point of view of re, a critical point for safety is where chimneys penetrate roofs or walls made of these materials. Currently, chimneys are tested according to the European standard EN 1859, that prescribes the heat stress test and the thermal shock test for verifying the safety distance from combustible materials to avoid overheating. Despite the certi cation, in some European countries the number of roof res due to the presence of chimneys is high. The goal of the study presented in the thesis is to understand heat transfer between chimneys and roofs, and to propose a solution to roof res problem. A rst result of this work has been the identi cation of the weaknesses of the current certi cation procedure, which can lead to the overheating of ammable materials and re hazard in some real installations. For this, modi cations to the standard will be proposed. With the aim to respond to the needs of the installers, by means of a 2D and a 3D numerical models designed to estimate the steady-state temperature on ammable materials and validated by means of experimental tests, it has been possible to identify all the variables a ecting the heat transfer between chimney and roof, and to collect data to study the problem statistically by means of the ANOVA technique. The results of the statistical analysis have been represented in the form of tables by means of which it is possible to identify the characteristics of the chimney to be installed in a given roof for avoiding the overheating of ammable materials. Also a heating curve model for the estimation of the steady-state temperature from the temperature-time curves measured in experimental tests is proposed in the thesis. Finally, the characteristics of a device to be installed between chimney and roof to prevent the overheating of ammable materials have been identi ed, and the principle on which it is based is the coupling of conductive and insulating materials. The device should guarantee limited temperature on ammable materials also in conditions more critical than those prescribed by the EN 1859 standard.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Ahmad, Nia Pardis. "Shading and natural ventilation, addressing indoor overheating in the present and future through the case study of Bysjöstrand eco-village". Thesis, Högskolan Dalarna, Institutionen för information och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:du-38054.

Texto completo

Resumen

Climate change temperatures expected to rise and extreme heat events (HW) canbe intensified. The influence of climate change on the built environment willbecame more apparent over the coming years. For example, there would be ashift in the risk of overheating in buildings, as well as the cooling and heatingneeds.Studies found that design strategies used to optimize buildings for winter like:good thermal insulation, high airtightness, and extra heat gains increase the riskof overheating. Thus, because of climate change, there is a need for checking thebuildings for summer conditions even in heating dominated countries.This study aims to investigate the potential of two main passive design strategiesto mitigate indoor overheating: ventilation and shading. The main focus of thisstudy is on single-family homes within the Swedish context. Bysjöstrand EkobyAssociation’s Bysjöstrand eco-village project is used as case study. 30 singlefamilyhomes are simulated using Honeybee to run EnergyPlus for calculatingindoor mean air temperature values, extracting the number of hour andpercentages of overheating for each building.Six alternative scenarios were used to evaluate the eco-village. The firststructures were assessed to determine the hours and percentage of time spentoverheating in the present and future situations. The second scenarios, whichinvolved utilizing natural ventilation, was tested to determine if and to what extentit can help to reduce the overheating risk in present and future.A combination of natural ventilation and shading was used for the last scenariosboth for current and future climate.According to the findings, natural ventilation has the greatest influence in reducingoverheating. Combining these two strategies in 2020 and 2070 can lower theaverage percentages of overheating from 17.5 % to 0.6 % and 52.8 % to 12.4%,respectively.The majority of the overheating risk may be addressed using passive strategies,based on the results. More detailed building design is likely be able to eliminateoverheating in single family homes, however, as this study showed it is importantto consider passive strategies from the early stage on the design process.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Tink, Victoria J. "The measured energy efficiency and thermal environment of a UK house retrofitted with internal wall insulation". Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/33727.

Texto completo

Resumen

Approximately 30% of the UK s housing stock is comprised of older, solid wall buildings. Solid walls have no cavity and were built without insulation; therefore these buildings have high heat loss, can be uncomfortable for occupants throughout the winter and require an above-average amount of energy to heat. Solid wall buildings can be made more energy efficient by retrofitting internal wall insulation (IWI). However, there is little empirical evidence on how much energy can be saved by insulating solid wall buildings and there are concerns that internal wall insulation could lead to overheating in the summer. This thesis reports measured results obtained from a unique facility comprised of a matched pair of unoccupied, solid wall, semi-detached houses. In the winter of 2015 one house of the pair was fitted with internal wall insulation then both houses had their thermal performance measured to see how differently they behaved. Measuring the thermal performance was the process of measuring the wall U-values, the whole house heat transfer coefficient and the whole house airtightness of the original and insulated houses. Both houses were then monitored in the winter of 2015, monitoring was the process of measuring the houses energy demand while using synthetic occupancy to create normal occupancy conditions. In the summer of 2015 indoor temperatures were monitored in the houses to assess overheating. The monitoring was done firstly to see how differently an insulated and an uninsulated house perform under normal operating conditions: with the blinds open through the day and the windows closed. Secondly, a mitigation strategy was applied to reduce high indoor operative temperatures in the houses, which involved closing the blinds in the day to reduce solar gains and opening the windows at night to purge warm air from the houses. The original solid walls were measured to have U-values of 1.72 W/m2K, while with internal wall insulation the walls had U-values of 0.21 W/m2K, a reduction of 88%. The house without IWI had a heat transfer coefficient of 238 W/K; this was reduced by 39% to 144 W/K by installing IWI. The monitored data from winter was extrapolated into yearly energy demand; the internally insulated house used 52% less gas than before retrofit. The measured U-values, whole house heat loss and energy demand were all compared to those produced from RdSAP models. The house was found to be more energy efficient than expected in its original state and to continue to use less energy than modelled once insulated. This has important implications for potential carbon savings and calculating pay-back times for retrofit measures. In summer, operative temperatures in the living room and main bedroom were observed to be higher, by 2.2 oC and 1.5 oC respectively, in the internally insulated house in comparison to the uninsulated house. Both of these rooms overheated according to CIBSE TM52 criteria; however the tests were conducted during an exceptionally warm period of weather. With the simple mitigation strategy applied the indoor operative temperature in the internally insulated house was reduced to a similar level as observed in the uninsulated house. This demonstrates that any increased overheating risk due to the installation of internal wall insulation can be mitigated through the use of simple, low cost mitigation measures. This research contributes field-measured evidence gathered under realistic controlled conditions to show that internal wall insulation can significantly reduce the energy demand of a solid wall house; this in turn can reduce greenhouse gas emissions and could help alleviate fuel poverty. Further to this it has been demonstrated that in this archetype and location IWI would cause overheating only in unusually hot weather and that indoor temperatures can be reduced to those found in an uninsulated house through the use of a simple and low cost mitigation strategy. It is concluded that IWI can provide a comfortable indoor environment, and that overheating should not be considered a barrier to the uptake of IWI in the UK.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Sousa, Tonnyfran Xavier de Araujo. "Analise do efeito do superaquecimento na solidificação unidirecional da liga AA5052". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265165.

Texto completo

Resumen

Orientador: Rezende Gomes dos Santos
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-06T09:53:26Z (GMT). No. of bitstreams: 1 Sousa_TonnyfranXavierdeAraujo_M.pdf: 6216112 bytes, checksum: 8c56f86b7dd957a9bef95dc947db6ed6 (MD5) Previous issue date: 2006
Resumo: O objetivo do trabalho é o desenvolvimento de uma análise comparativa do processo de solidificação de uma liga de alumínio a partir de diferentes graus de superaquecimento. São determinados experimentalmente os principais parâmetros do processo de solidificação afetados pelo grau de superaquecimento e sua influência na formação da microestrutura. Foi escolhida a liga AA5052, contendo cerca de 3% de magnésio pelo seu interesse comercial. A liga foi vazada com três diferentes graus de superaquecimento, em um dispositivo que permite a solidificação unidirecional e o monitoramento, através de um sistema de aquisição de dados, das variações de temperatura em diferentes posições da peça. A partir dos resultados de temperatura são determinados outros parâmetros do processo. Os espaçamentos interdendriticos são determinados a partir das micrografias. Através da análise experimental é determinada a influência do grau de superaquecimento nos seguintes parâmetros relativos ao processo de solidificação: coeficiente de transferência de calor na interface metal/molde, velocidade de avanço da frente de solidificação, gradiente de temperatura em frente à isoterma liquidus, taxa de resfriamento, tempo local de solidificação e espaçamentos interdendriticos primário e secundário. Também é analisada a transição entre a estrutura colunar e equiaxial
Abstract: The objective of this work is the development of a comparative analysis of solidification process of the aluminum 5052 alloy with different overheating ranges. The main parameters of the solidification process, experimentally determined, are affected by the overheating range and its influence on the microstructure arrangement. lt was selected the 5052 alloy, containing about 3% of magnesium, used for commercial purposes. The al1oy was poured with three different overheating ranges in a device which allows the unidirectional solidification and its monitoring through an acquisition data system thru the temperature variation from different positions on the sample. From the temperature results, the process parameters are determined. The dendritic spacing is determined using the micrographs. Through experimental analysis is established the influence of the overheating range at the fol1owing parameters related to solidification process: heat transfer coefficient at the metal/mold interface, solidification rate, thermal gradient at the liquidus isotherm, cooling rate, local solidification time and secondary arm spacing. The change between the structure columnar and equiaxed is also studied.
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Bawana, Niyem Mawenbe. "Thermal Response in a Field Oriented Controlled Three-phase Induction Motor". Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7740.

Texto completo

Resumen

The research conducted at the department of Electrical Engineering of the University of South Florida campus in Tampa only covers the electrical aspect of electric drives. However, the performance of electric machinery is significantly impacted by temperature variation. The literature review shows three main control techniques in use today in electric drives namely, Scalar control, Direct Torque control and Field Oriented control. This thesis presents a temperature rise of rotor bars, stator winding, stator core and stator frame in a running three phase field-oriented controlled induction machine. A literature search shows that none of research has been carried out to investigate a thermal response of a field-oriented controlled induction motor. With this motivation, we were able to implement a lumped parameters thermal model of a three-phase field-oriented IM in MATLAB Simulink, which allows us to determine that rotor bars have the highest temperatures rising to 84 degrees Celsius. This confirms that rotors bars are the hottest part of a running IM as stipulated in literature.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Mballo, Souleymane. "Quantification et modélisation des services climatiques rendus par les arbres dans une rue canyon". Thesis, Rennes, Agrocampus Ouest, 2022. http://www.theses.fr/2022NSARD097.

Texto completo

Resumen

Le changement climatique global et les épisodes extrêmes qu’il induit sont devenus l’un des enjeux majeurs de ce siècle. La compréhension du microclimat en milieu urbain suscite une attention croissante de la part des chercheurs depuis quelques années, en raison des phénomènes de surchauffe observés en ville et de la densité de population qui en font un environnement sensible aux vagues de chaleur. De nombreuses études ont montré que la végétation peut réduire la température de l’air en ville, mais ces bénéfices dépendent de l'environnement construit, et de nombreuses variables souvent non maitrisées en ville, comme la disponibilité de l'eau pour les végétaux. Dans ce contexte, ce travail de thèse vise à analyser et quantifier les services climatiques rendus dans une rue canyon par des arbres en confort hydrique. Elle s’appuie sur une double approche associant expérimentation et modélisation. Des campagnes de terrain ont été réalisées sur une maquette arborée à l’échelle (1/5) installée en milieu extérieur sur le site de l’Institut Agro, à Angers, France. Sur le plan numérique, des simulations 2D du climat distribué en régime instationnaire ont été réalisés selon une approche de type CFD. Entre autres résultats, les travaux de cette thèse ont montré que la rue canyon crée une surchauffe pouvant aller jusqu’à 2.8 °C pendant la nuit, et jusqu'à 2.4°C pendant la journée, et que les arbres peuvent réduire la température de l'air dans la rue de 2.7 °C pendant la journée et améliorer le confort humain thermique en réduisant jusqu’à 8 °C les valeurs de l’UTCI à la mi-journée. Ce travail fournit des éléments de quantification qui pourront aider les décideurs dans leur politique d’aménagement
Global climate change and the extreme events it induces have become one of the major issues of this century. Understanding the microclimate in urban areas has received increasing attention from researchers in recent years, due to the overheating phenomena observed in cities and the population density that makes them a sensitive environment for heat waves. Several studies have shown that vegetation can reduce air temperature in cities, but these benefits depend on the built environment, and on many variables often not controlled in cities, such as water availability for plants. In this context, this thesis aims to analyze and quantify the climatic services provided in a canyon street by well-watered trees. It is based on a double approach combining experimentation and modeling. Field campaigns were carried out on a tree model at scale (1/5) installed in an outdoor environment on the site of the Institut Agro, in Angers, France. On the numerical approach, 2D simulations of the distributed climate in unsteady regime were performed using a CFD approach. Among other results, the work of this thesis showed that the canyon street creates overheating of up to 2.8 °C during the night, and up to 2.4 °C during the day, and that trees can reduce the air temperature in the street by 2.7 °C during the day, and improve human thermal comfort by reducing mid-day UTCI values by up to 8 °C. This work provides quantification elements that can help decision makers in their planning policies

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Lämmle, Manuel [Verfasser] y Hans-Martin [Akademischer Betreuer] Henning. "Thermal management of PVT collectors : : development and modelling of highly efficient glazed, flat plate PVT collectors with low emissivity coatings and overheating protection". Freiburg : Universität, 2018. http://d-nb.info/1168145651/34.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Bartkevičiūtė, Viktorija. "Lietuvos ekonomikos perkaitimo įvertinimas: pasiūlos aspektas". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080821_150136-93002.

Texto completo

Resumen

Pastaruoju metu ekonomikos perkaitimas tapo daugumos ekonomikos analitikų svarstoma tema. Šio mokslinio darbo pagrindinis tikslas – patikslinti ekonomikos perkaitimo apibrėžimą ir pasiūlyti prie apibrėžimo adaptuotą ekonomikos perkaitimo vertinimo metodiką. Pirmoje šio mokslinio darbo dalyje, remiantis ekonomikos mokslinės literatūros analize, atskleistas nepakankamas ekonomikos perkaitimo problematikos ištyrimo lygis – trūksta ekonomikos perkaitimo konkretaus apibrėžimo ir jo vertinimo tikslumo. Šios problematikos sprendimo sritys bus tobulinamos tolesniuose šio darbo skyriuose. Antroje šio mokslinio darbo dalyje pagal pirmoje darbo dalyje išanalizuotas ekonomikos perkaitimo metodikas pasirenkami perkaitimo rodikliai, susiję su paklausa, atliekama naujausia jų analizė ir įvertinama Lietuvos ekonomikos perkaitimo grėsmė. Perkaitimo rodiklių analizės eigoje atskleistas nepakankamas ekonomikos perkaitimo įvertinimas, nes akcentuojami tik paklausos veiksniai, netiriamas pasiūlos vaidmuo. Atsižvelgiant į ekonomikos perkaitimo problematikos ištyrimo lygį ir neįvertintą pasiūlos vaidmenį, paskutinėje šio mokslinio darbo dalyje pateikiamas ekonomikos perkaitimo mechanizmas pasiūlos aspektu ir pasiūlomas pakoreguotas ekonomikos perkaitimo metodas, kurio pagalba įvertinama Lietuvos ekonomikos perkaitimo grėsmė.
The economic overheating recently became a topic of discussions among majority of economic analysts. The purpose of this scientific work is to present the definition of economic overheating in the aspect of supply and to propose the evaluation methodic of economic overheating. In the first part of this work, referring to the analysis of scientific literature, the insufficient level of investigation of economic overheating topic is revealed – there is a lack of concrete economic overheating definition and it‘s precise evaluation. The fields of solutions for these topics will be developed in further chapters. In the second part of this scientific work according to the analyzed economic overheating methodology in the first part the overheating indexes, bounded to demand, are chosen, the newest analysis of these indexes is implemented and the evaluation of economic overheating risk in Lithuania is done. In the progress of analysis of economic overheating indexes the insufficient evaluation of economic overheating is revealed, because only the demand‘s factors are being highlighted, the impact of supply was not investigated. Taking into consideration the level of economic overheating problem‘s evaluation and the fact that the supply‘s impact was not estimated, in the last part of this scientific work the economic overheating mechanism in the aspect of supply is presented and the improved economic overheating method is offered, with which help the evaluation of economic... [to full text]

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Aunes, Mattias y Erik Luhr. "From Wall Street to Norrmalmstorg : The Subprime Crisis in a Kindleberger framework and how it affected Swedish banks". Thesis, Uppsala University, Department of Business Studies, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88770.

Texto completo

Resumen

This thesis examines the subprime crisis in a Kindleberger framework as well as how the major banks in Sweden were affected. The thesis ties different events to the framework of Kindleberger and follows the stages he sees in a financial crisis, from the origination of the crisis due to speculation to suggested structural changes in the financial market. The effects upon Swedish banks are followed through the crisis and the effects upon the banks. Conclusions drawn are that the Kindleberger model is applicable to the subprime crisis in terms of components and not always chronologically. Swedish banks have regarding the magnitude of the crisis faired well, the problems causing the crisis are related to Moral hazard problems, regulators and rating institution.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Макаренко, Михайло Ілліч, Михаил Ильич Макаренко y Mykhailo Illich Makarenko. "Теоретичні аспекти інструментальної обмеженості грошово-кредитної політики центральних банків". Thesis, Київський національний торговельно-економічний університет, 2013. http://essuir.sumdu.edu.ua/handle/123456789/59347.

Texto completo

Resumen

Глибина останньої фінансово-економічної кризи була настільки значною, що традиційні інструменти державного антикризового регулювання економіки виявились мало-спроможними для оперативного і дієвого подолання макроекономічної турбулентності. Грошово-кредитна політика (ГКП), яка, здебільшого, використовувалась для підтримання цінової стабільності на національному товарному ринку, у стандартному ліберальному вигляді виявилась нездатною істотно вплинути на потужний рецесійний шок 2007-2008 рр. Через це центральні банки ряду країн як провідники ГКП вдались до запровадження в дію заходів нетрадиційного характеру, які в поєднанні з класичними спрацювали на пом'якшення перебігу та наслідків глобальної нестабільності.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Quigley, Ella S. "The energy and thermal performance of UK modular residential buildings". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/25127.

Texto completo

Resumen

This research concerns the in-use performance of light-gauge steel modular construction used for residential purposes. The aim was to investigate ways to reduce the in-use energy consumption of new buildings, while ensuring thermal comfort. Data were collected from two case study buildings in the UK, one in Loughborough and the other in London, using a variety of methods including building measurement, building monitoring, inspections, and a detailed review of the construction documentation. The case study buildings were monitored using EnOcean enabled wireless sensor networks and standalone temperature sensors. Monitoring data included electricity consumption in individual rooms, often by end use, space heating use, internal temperature and relative humidity, and external temperature. Building measurements included blower door tests to measure fabric air leakage rates, infrared thermal imaging to identify fabric defects and weaknesses, and ventilation system flowrate measurements. Inspections and the review of documentation allowed problems with design, manufacture and construction to be identified. A particular concern for thermally lightweight construction is the risk of overheating, therefore overheating analyses were undertaken. The research identified weaknesses in the design, construction and operation of the case study buildings resulting in increased energy use and poor thermal comfort, particularly overheating. The modular construction studied requires specific design changes to improve the fabric and building services, in order to reduce energy use. There are also specific recommendations for quality control on site to ensure critical stages are correctly completed, such as installing rigid insulation. There are also more general recommendations for how a company operates because this can influence performance; there ought to be greater attention to holistic design and greater collaboration with suppliers and contractors to determine robust solutions. Overheating was a problem in the London case study, and more research is required to understand the scale of the problem. Avoidance of overheating must be a focus in the design of new buildings. The findings suggest that once the problems with the design and quality control on site are rectified, offsite modular construction can be used to consistently and reliably provide low energy homes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Matour, Soha. "A new design for double skin facade in warm climates: Improving thermal performance and natural ventilation of the system". Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/231909/1/Soha_Matour_Thesis.pdf.

Texto completo

Resumen

This thesis contributes to the improvement of Double Skin facades' thermal performance in warm climates. A new design for DSF was proposed and evaluated using an experimental study on a scaled model and Computational Fluid Dynamics simulations. The proposed facade named IS-DSF (Interstitial slat-blind DSF) showed the capability to reduce overheating risk in the cavity due to two applied strategies: shading devices’ specific placement and wind-induced ventilation improvement. Finally, a framework was developed for the implementation of IS-DSF in warm climates applicable at the early stage of building design.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Tettey, Uniben Yao Ayikoe. "Primary energy use of residential buildings : implications of materials, modelling and design approaches". Doctoral thesis, Linnéuniversitetet, Institutionen för byggd miljö och energiteknik (BET), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-61470.

Texto completo

Resumen

Buildings can play an essential role in the transition to a sustainable society. Different strategies, including improved energy efficiency in buildings, substitution of carbon intensive materials and fuels, efficient energy supply among others can be employed for this purpose. In this thesis, the implications of different insulation materials, modelling and design strategies on primary energy use of residential buildings are studied using life cycle and system perspective. Specifically, the effects of different insulation materials on production primary energy and CO2 emission of buildings with different energy performance are analysed. The results show that application of extra insulation materials to building envelope components reduces the operating primary energy use but more primary energy is required for the insulation material production. This also slightly increases the CO2 emissions from material production. The increases in primary energy use and CO2 emissions are mainly due to the variations in the quantities, types and manufacturing processes of the insulation materials. Thus, choice of renewable based materials with energy efficient manufacturing is important to reduce primary energy use and GHG emissions for building material production. Uncertainties related to building modelling input parameters and assumptions and how they influence energy balance calculations of residential buildings are explored. The implications on energy savings of different energy efficiency measures are also studied. The results show that input data and assumptions used for energy balance simulations of buildings vary widely in the Swedish context giving significant differences in calculated energy demand for buildings. Among the considered parameters, indoor air temperature, internal heat gains and efficiency of ventilation heat recovery (VHR) have significant impacts on the simulated building energy performance as well as on the energy efficiency measures. The impact of parameter interactions on calculated space heating of buildings is rather small but increases with more parameter combinations and more energy efficient buildings. Detailed energy characterisation of household equipment and technical installations used in a building is essential to accurately calculate the energy demand, particularly for a low energy building. The design and construction of new buildings present many possibilities to minimise both heating and cooling demands over the lifecycle of buildings, and also in the context of climate change. Various design strategies and measures are analysed for buildings with different energy performance under different climate scenarios. These include household equipment and technical installations based on best available technology, bypassing the VHR unit, solar shading of windows, combinations of window u- and g-values, different proportions of glazed window areas and façade orientations and mechanical cooling. The results show that space heating and cooling demands vary significantly with the energy performance of buildings as well as climate scenarios. Space heating demand decreases while space cooling demand and the risk of overheating increase considerably with warmer climate. The space cooling demand and overheating risk are more significant for buildings with higher energy performance. Significant reductions are achieved in the operation final energy demands and overheating is avoided or greatly reduced when different design strategies and measures are implemented cumulatively under different climate change scenarios. The primary energy efficiency of heat supply systems depends on the heat production technology and type of fuel use. Analysis of the interaction between different design strategies and heat supply options shows that the combination of design strategies giving the lowest primary energy use for space heating and cooling varies between heat supply from district heating with combined heat and power (CHP) and heat only boilers (HOB). The primary energy use for space heating is significantly lower when the heat supply is from CHP rather than HOB. Operation primary energy use is significantly reduced with slight increase in production primary energy when the design strategies are implemented. The results suggest that significant primary energy reductions are achievable under climate change, if new buildings are designed with appropriate strategies.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Lazar, Paul. "Transport mechanisms and wetting dynamics in molecularly thin films of long-chain alkanes at solid/vapour interface : relation to the solid-liquid phase transition". Phd thesis, Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2005/527/.

Texto completo

Resumen

Wetting and phase transitions play a very important role our daily life. Molecularly thin films of long-chain alkanes at solid/vapour interfaces (e.g. C30H62 on silicon wafers) are very good model systems for studying the relation between wetting behaviour and (bulk) phase transitions. Immediately above the bulk melting temperature the alkanes wet partially the surface (drops). In this temperature range the substrate surface is covered with a molecularly thin ordered, solid-like alkane film ("surface freezing"). Thus, the alkane melt wets its own solid only partially which is a quite rare phenomenon in nature. The thesis treats about how the alkane melt wets its own solid surface above and below the bulk melting temperature and about the corresponding melting and solidification processes.
Liquid alkane drops can be undercooled to few degrees below the bulk melting temperature without immediate solidification. This undercooling behaviour is quite frequent and theoretical quite well understood. In some cases, slightly undercooled drops start to build two-dimensional solid terraces without bulk solidification. The terraces grow radially from the liquid drops on the substrate surface. They consist of few molecular layers with the thickness multiple of all-trans length of the molecule. By analyzing the terrace growth process one can find that, both below and above the melting point, the entire substrate surface is covered with a thin film of mobile alkane molecules. The presence of this film explains how the solid terrace growth is feeded: the alkane molecules flow through it from the undercooled drops to the periphery of the terrace.
The study shows for the first time the coexistence of a molecularly thin film ("precursor") with partially wetting bulk phase. The formation and growth of the terraces is observed only in a small temperature interval in which the 2D nucleation of terraces is more likely than the bulk solidification. The nucleation mechanisms for 2D solidification are also analyzed in this work. More surprising is the terrace behaviour above bulk the melting temperature. The terraces can be slightly overheated before they melt. The melting does not occur all over the surface as a single event; instead small drops form at the terrace edge. Subsequently these drops move on the surface "eating" the solid terraces on their way. By this they grow in size leaving behind paths from were the material was collected. Both overheating and droplet movement can be explained by the fact that the alkane melt wets only partially its own solid. For the first time, these results explicitly confirm the supposed connection between the absence of overheating in solid and "surface melting": the solids usually start to melt without an energetic barrier from the surface at temperatures below the bulk melting point. Accordingly, the surface freezing of alkanes give rise of an energetic barrier which leads to overheating.
Sowohl Benetzung als auch Phasenübergänge spielen eine sehr wichtige Rolle im täglichen Leben. Molekular dünne Filme langkettiger Alkane an Festkörper/Gas-Grenzflächen (z. B. C30H62 an Silizium-Waferoberflächen) sind sehr gute Modellsysteme um die Wechselbeziehung zwischen Benetzungsverhalten und (Volumen-)Phasenübergängen zu untersuchen. In einem Temperaturbereich knapp oberhalb der Volumenschmelztemperatur benetzt die Alkanschmelze die Substratoberfläche nur partiell (Alkantropfen). In diesem Temperaturbereich ist die Substratoberfläche mit einer molekular dünnen, festkörperartig geordneten Alkanschicht bedeckt ("Oberflächengefrieren" ). Die Alkanschmelze benetzt also die eigene Festkörperoberfläche nur partiell, ein in der Natur ziemlich seltenes Phänomen. Die Dissertation beschäftigt sich damit wie die Alkanschmelze ihre eigene Festkörperoberfläche über und unter dem Volumenschmelzpunkt benetzt und mit den entsprechenden Vorgängen beim Schmelzen bzw. Erstarren. Flüssige Alkantropfen lassen sich einige Grad unter ihren Schmelzpunkt unterkühlen ohne sich sofort zu verfestigen. Dieses "Unterkühlungsverhalten" ist üblich und es ist theoretisch qualitativ gut verstanden. Allerdings beobachtet man bei den Alkanen bei leichter Unterkühlung statt einer eventuellen Volumenverfestigung oft die Ausbildung von zweidimensionalen Terrassen aus erstarrtem Alkanen. Die Terrassen wachsen auf der Substratoberfläche radial aus den flüssigen Tropfen. Sie bestehen aus wenigen Alkanlagen mit jeweils der Dicke einer Moleküllänge. Die Analyse der Terrassen-Wachstumsprozesse zeigt, dass die gesamte Substratoberfläche einschliesslich der Terrassen sowohl oberhalb als auch unterhalb der Volumenschmelztemperatur mit einer dünnen Schicht mobiler Alkanmoleküle bedeckt ist. Durch diese Schicht fliessen bei Unterkühlung die Alkane vom unterkühlten Tropfen zur Terrassenkante und liefern den Nachschub für deren Wachstum. Die Untersuchungen zeigen damit erstmalig die Koexistenz eines molekular dünnen Films ("Precursor") mit einer partiell benetzenden Volumenphase. Die Entstehung und das Wachstum der Terrassen wird nur in einem engen Temperaturfenster beobachtet in dem die Keimbildung zweidimensionaler Terrassen wahrscheinlicher ist als die dreidimensionale Volumenverfestigung. Auch dieses Keimbildungsverhalten wird in der Dissertation genauer analysiert. Noch erstaunlicher als das Terrassenwachstum, d. h. das Verfestigungsverhalten ist das Schmelzverhalten der Terrassen. Sie lassen sich bis zu einer gewissen Temperatur überhitzen bevor sie schmelzen! Weiterhin findet bei genügender Überhitzung das Schmelzen nicht gleichzeitig überall statt sondern es entstehen zuerst kleine Alkantropfen an den Terrassenrändern. Diese bewegen sich dann über die Substratoberfläche und "fressen" sich durch die festen Terrassen. Dabei wachsen sie weil sie das geschmolzene Material aufnehmen und hinterlassen eine alkanfreie Spur. Sowohl die Überhitzung als auch die Tropfenbewegung lassen sich damit erklären dass die flüssige Alkanschmelze ihren eigenen Festkörper nur partiell benetzt. Die Ergebnisse bestätigen erstmals explizit den seit vielen Jahrzehnten vermuteten Zusammenhang zwischen der üblicherweise nicht beobachtbaren Überhitzung von Festkörpern und Oberflächenschmelzen: Festkörper beginnen normalerweise ohne Energiebarriere von der Oberfläche an zu schmelzen. Entsprechend bildet das Oberflächengefrieren der Alkane eine Energiebarriere und erlaubt damit deren Überhitzen.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Duran, Ozlem. "Evaluation of retrofitting strategies for post-war office buildings". Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/32268.

Texto completo

Resumen

The energy used in non-domestic buildings accounts for 18 % of the energy use in the UK. Within the non-domestic building stock, 11 % of office buildings have a very high influence on the energy use. Thus, the retrofit of office buildings has a significant potential for energy efficiency and greenhouse gas emissions reduction within the non-domestic building stock. However, the replacement rate of existing buildings by new-build is only around 1-3 % per annum. Post-war office buildings, (built between 1945 and 1985) represent a promising sector for retrofit and energy demand reduction. They have disproportionately high energy consumption because many were built before the building regulations addressed thermal performance. The aim of the research is to evaluate the retrofit strategies for post-war office buildings accounting for the improved energy efficiency, thermal comfort and hence, productivity, capital and the running costs. The research seeks to provide the optimal generic retrofit strategies and illustrate sophisticated methods which will be the basis for guidelines about post-war office building retrofit. For this, multiple combinations of heating and cooling retrofit measures were applied to representative models (Exemplar) of post-war office buildings using dynamic thermal simulation modelling. The retrofit strategies include; applying envelope retrofit to UK Building Regulations Part L2B and The Passivhaus Institue EnerPHit standards for heating demand reduction and winter comfort. Passive cooling interventions such as shading devices and night ventilation and active cooling intervention such as mixed-mode ventilation were applied to overcome summer overheating. All retrofit combinations were evaluated considering future climate, inner and outer city locations and different orientations. In summary, the results showed that under current weather conditions Part L2B standard retrofit with passive cooling provided the optimum solution. In 2050, however, both Part L2B retrofit naturally ventilated cases with the passive cooling measures and EnerPHit retrofit mixed-mode ventilation cases provide the requisite thermal comfort and result in a similar range of energy consumption. It was concluded that to create generic retrofit solutions which could be applied to a given typology within the building stock is possible. The methodology and the Exemplar model could be used in future projects by decision-makers and the findings and analysis of the simulations could be taken as guidance for the widespread retrofit of post-war office buildings.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Paťha, Vladimír. "Analýza běhu hnacího ústrojí vozidla po úniku provozních kapalin". Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-413824.

Texto completo

Resumen

This master’s thesis deals with the issue of damage of the vehicle’s drivetrain due to the operating fluid leakage. The aim of the thesis is to clarify the severity of this type of damage and, alternatively, the times during which these failures can occur. The theoretical part describes the issues of lubrication and cooling systems, including the consequences of sub-optimal operating conditions. The evaluation is based on conducted experiments and is compared with already published tests. The parts that are most often damaged are also described. Finally, the recommendations for lowering the extent of damage are formulated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Höglund, Marcus y Anton Stenås. "Komfort- och energianalys vid installation av markiser på Högskolans i Gävle glasfasader : Mätningar och IDA ICE-simuleringar". Thesis, Högskolan i Gävle, Energisystem och byggnadsteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-36108.

Texto completo

Resumen

Högskolan i Gävle planerar att installera solavskärmande markiser på entréhallarnas sydliga glasade fasader. Sedan uppbyggnad har entrébyggnaden som inkluderar ”Rävhallen” och ”Fårhallen” lidit av bristfällig termisk inomhuskomfort på grund av värmeläckage och överhettning orsakade av fasadernas fönsterpartier. Detta examensarbete gjordes i syfte att via mätningar undersöka den termiska inomhuskomforten i Högskolans i Gävle entréhallar. Arbetet syftade också till att årssimulera och analysera årlig energiförbrukning och termisk inomhuskomfort innan och efter installationen av solavskärmande markiser på byggnadens glasfasader, i simuleringsprogrammet IDA ICE. En komfortundersökning gjordes genom att mäta termisk komfort och inomhustemperaruter under två tillfällen i april månad. Mätningarna gjordes under en molnig dag och en solig dag vid samma utomhustemperatur, för att undersöka solinstrålningens inverkan på byggnadens termiska komfort och inomhustemperaturer. Komfortundersökningen visade att den termiska komforten i Rävhallen och Fårhallen var undermålig då överhettning uppstår vid hög solinstrålning. Nödvändiga data inför modellering och simulering insamlades genom observationer, uppskattning, beräkningar och samtal med drifttekniker vid Akademiska hus. Efter datainsamlingen konstruerades en modell i simuleringsprogrammet IDA ICE. Innan simulering validerades modellen med hjälp av tidigare uppmätta temperaturer under april månad. Sedan simulerades byggnadens energiförbrukning och termiska inomhuskomfort över ett helt år, utan markiser, och därefter med markiser. Resultatet visade att den termiska komforten förbättrades markant vid installation av markiser. Höga topptemperaturer som tidigare förekom i byggnaden minskade eftersom markiserna reducerade solinstrålningen genom fasadens fönsterpartier. Det totala årliga energibehovet ökade dock från 605 MWh till 635 MWh. Det årliga energibehovet för kyla minskade något från 3,4 MWh till 3,2 MWh. Att energiförbrukningen ökade berodde på att markiserna reducerade nyttig gratisvärme från solinstrålningen, särskilt under uppvärmningssäsong. För vidare forskning föreslås en mer effektiv styrteknik av markiserna och en mer detaljrik simuleringsmodell för att få tillförlitligare resultat. Vid tillämpning av bättre anpassad styrning av markiserna bedöms energibesparingspotentialen bli större. Slutsatsen drogs att markiser kan förbättra den termiska inomhuskomforten avsevärt, men att energiförbrukningen kan komma att öka beroende på styrteknik.
The University of Gävle plans to install solar shading awnings on the southern glass facades of the main entrances. Since construction, the main entrances Rävhallen and Fårhallen have suffered from poor thermal indoor comfort due to heat leakage and overheating due to the windows on the facades. This thesis was done in order to map and investigate the thermal indoor comfort in the University of Gävle's main entrances. The work also aimed to simulate and analyze annual energy consumption and thermal indoor comfort before and after the installation of solar shading awnings on the building's glass facades, in the simulation program IDA ICE. A comfort survey was conducted by measuring thermal comfort and indoor temperature ranges on two occasions in April. The measurements were made during a cloudy day and a sunny day at the same outdoor temperature, to investigate the effect of solar radiation on the building's thermal comfort and indoor temperatures. The comfort survey showed that the thermal comfort in Rävhallen and Fårhallen was insufficient as overheating occurs at high solar radiation. Data necessary for modeling and simulation was collected through observations, estimates, and dialogs with operating technicians from Akademiska hus. After data collection, a model was constructed in the simulation program IDA ICE. Before simulation, the model was validated using previously measured temperatures during the month of April. Then the building's energy consumption and thermal indoor comfort were simulated over a whole year, without awnings, and with awnings. The results showed that the thermal comfort was significantly improved by the awnings installations. High peak temperatures that previously occurred in the building decreased because of the reduced solar radiation through the glass facade. The total annual energy demand increased from 605 MWh to 635 MWh. However, the annual energy demand for cooling decreased from 3,4 MWh to 3,2 MWh. The increase in energy consumption was due to the awnings reducing useful heat from solar radiation, especially during the heating season. Prior to further research, a more efficient control technique of the awnings and a more detailed model to improve the simulation results are proposed. When applying better adapted control of the awnings, the energy saving potential is considered to be greater. It was concluded that awnings can significantly improve indoor thermal comfort, but that energy consumption may increase depending on control technology.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Quijada, Ezequiel. "Thermal Analysis of a Sea Wave Generator". Thesis, KTH, Elkraftteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209197.

Texto completo

Resumen

Wave power has been increasing the interest of many researchers looking for alternative sustainable energy sources since the reserves have proved to be capable of satisfying a considerable percentage of the world´s energy demands. This option has not been adopted as a sustainable source since there are some challenges in the process of designing a low cost device that converts the kinetic energy of the waves into electric energy and that could still be efficient enough to be competitive against other options. A new proposal from Anders Hagnestål looks like a very promising way of moving forward in this field. The structure of this newly proposed generator includes neodymium magnets that at temperatures over 60°C might suffer irreversible demagnetization, compromising the normal functioning of the machine. Because of the electrical losses in iron components, overheating is a possibility that must be studied. The aim of this study is to find the temperature distribution of the components that are subject to changing magnetic fields (where the losses will occur). This will be done for a variety of cases regarding environmental and working conditions with the purpose of determining if the generator will need a cooling technique to avoid damage to the magnets. The studied structure consists of a stator and a translator conformed by iron, FR4, glass fiber and, of course, the magnets. The task at hand was carried out first through a one-dimensional analytical model, then through a two-dimensional analytical model and finally by means of simulations on Comsol Multiphysics (Computer-Aided-Engineering software). All of the aforementioned methods implicate assumptions that deviate from reality, but are still useful for the task at hand. Results from the 1D calculation turned out to be unreliable due to the numerous approximations but helped to prove and understand the effect of each of the environmental conditions on the temperature distribution. On the other hand, the 2D calculations and the simulations had a very good agreement which provides some reliability. Furthermore, said results showed that the components might even reach temperatures as high as 380°C under certain conditions. As this number is clearly over the safe limit of the magnets, it was concluded that cooling techniques are needed to ensure the safety of the generator. After some discussion with Hagnestål, cooling methods were proposed. In addition to this, the seemingly most appropriate option was pointed out with the intention of achieving a low-enough temperature and keeping the costs as low as possible. This alternative was a combination of modifying geometric parameters (which would ultimately reduce heat generation) and inducing a low velocity air flow.
Vågkraft är en hittills outnyttjad förnybar energikälla som i framtiden kan tillgodose i storleksordningen 10 % av världens energibehov, om de tekniska utmaningarna kan lösas så att vågkraft kan levereras till konkurrenskraftiga priser. Därmed finns också ett starkt intresse från både akademi och näringsliv att lösa dessa utmaningar. Anders Hagnestål håller på att utveckla en ny linjär generatortyp som enligt beräkningar slår alla befintliga lösningar för effektomvandling för vågkraft med bred marginal. Maskinen har dock komplex geometri, och det är svårt att beräkna dess prestanda. Maskinen innehåller neodymmagneter, vilka kan avmagnetiseras om de blir för varma där 60°C kan ses som en gräns då magneterna börjar påverkas. Om magneterna avmagnetiseras blir maskinen svagare. Eftersom magneterna upphettas av virvelströmmar i magneterna och förluster i omgivande elektroplåt, är det av intresse att göra en termisk analys av maskinen vilket är syftet med detta examensarbete. Målet är att beräkna temperaturutbredningen i maskinens olika delar vid olika driftsfall, och se om man behöver tillföra extern kylning av maskinen för att skydda magneterna. Maskinen består av en translator som omsluter den inre statorn där magneterna är lokaliserade, vilka är byggda av fiberkompositer, elektroplåt, rostfritt stål och neodymmagneter. Beräkningar gjordes först med en endimensionell analytisk modell, därefter med en tvådimensionell analytisk modell och slutligen med numeriska beräkningar i 2D med det kommersiella finita elementmetodberäkningsprogrammet Comsol Multiphysics. Samtliga dessa modeller har avvikelser från det verkliga fallet, men är ändå användbara och ger en fingervisning om hur den termiska situationen för maskinen kan se ut. 1D-beräkningarna visade sig innehålla lite för grova approximationer för att ge pålitliga resultat, men gav en del intuitiv insikt om problemet. Den analytiska 2D-beräkningen stämde bra överens med Comsol-beräkningen, vilket indikerar att beräkningarna är korrekta. Resultaten visade på mycket höga temperaturer i vissa driftsfall utan kylsystem, 380 °C, vilket är en indikator på att antingen någon form av kylning förmodligen behövs, i.a.f. i en del driftsfall, eller att värmeförlusterna i den delen av generatorn behöver minskas genom t.ex. att pollängden ökas. En kombination av luftflöden med låg hastighet och förändrad geometri har föreslagits i examensarbetet för att minska temperaturen.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Sanna, Fausto. "Timber modern methods of construction : a comparative study". Thesis, Edinburgh Napier University, 2018. http://researchrepository.napier.ac.uk/Output/1256099.

Texto completo

Resumen

The doctoral research revolves around a comparative study of timber modern methods of construction for low-rise, residential buildings in Scotland. The building techniques studied involve both timber-frame panel construction (open-panel and closed-panel systems and structural insulated panels) and massive-timber construction (cross-laminated and nail-laminated timber panels). A non-timber technique is also included in the study: more traditional, load-bearing masonry (blockwork). These different building techniques have been analysed from two complementary aspects: environmental impacts and thermal performance. The environmental study is based on the life-cycle assessment methodology and embraces various aspects: environmental impacts (e.g., climate change, acidification, eutrophication, ozone depletion, etc.), consumption of energy (renewable and non-renewable resources) and production of waste (from non-hazardous to radioactive). The assessment takes a cradle-to-gate approach and, in its structure and method, is informed by the current recommendations of the international standards in the field (i.e., ISO 14040 series). Various environmental trade-offs between construction methods have been identified. In terms of global-warming potential (excluding biogenic carbon sequestration), results suggest that timber-frame buildings show a better performance than masonry buildings; this is particularly true for the open-panel system, which emits about 10% less carbon than the masonry counterpart. Massive-timber buildings tend to cause more carbon emissions than masonry ones. In terms of consumption of non-renewable primary energy, timber buildings do not generally show significant advantages with respect to blockwork-based masonry. In particular, structural-insulated panel systems tend to show very high energy requirements. Timber-based buildings show a tendency to cause increased acidification, eutrophication and creation of low ozone than their masonry counterpart. The level of offsite fabrication that is employed for the erection of the buildings plays an important role in the magnitude of most environmental impacts, which show an average decrease between 5% and 10% when some of the operations are shifted from the construction site to the factory. v The thermal study investigates the performance of the building envelope, and, in particular, of external walls, by means of tests whereby the thermal behaviour of a sample of walls (of full-size section) has been observed and measured over time. On the outside, the walls were exposed to real, natural weather variations throughout the summer. The study especially focuses on the time-dependent response of three different walling systems (which results from their individual cross-sectional arrangements of building components and the associated combination of heat-storage capacity and thermal resistance): a timber-framed wall, a cross-laminated-timber wall and a masonry wall. Thus, the main goal of the study was to characterise the thermal-inertia parameters of these walls. This type of thermal behaviour is related to the repercussions of global climate change at UK level, especially in terms of increase in solar irradiance and temperature, which requires an adaptation of the building-envelope such that it can perform well both during wintertime and summertime, by providing maximum indoor comfort with minimum economic and environmental costs from the construction and operation of buildings. The timber-framed wall possesses the greatest capacity to slow down the propagation of temperature waves from the outer surface to the inner surface (time lag), whereas the masonry wall performs best with respect to reducing the amplitude of temperature oscillation on the inner surface (decrement factor). The cross-laminated-timber wall exhibits intermediate values of both time lag and decrement factor, relative to the other two walls. Both the thermal and life-cycle assessment of the construction alternatives aim at assisting the design and decision-making process in the residential field and at suggesting areas that need to be addressed and improved, towards a coherent evolution of the building techniques included in this study and a step forward in the realisation of sustainable, low-rise dwellings.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Martinka, David. "Vliv klimatických podmínek na bezdrátové routery". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377109.

Texto completo

Resumen

This thesis deals with problematics of installing wireless routers into specific locations depending on their heating and ideal signal transmission. The thesis is divided into eight chapters. The beginning of the thesis is theoretical describes the introduction into the problematics, the second part is practical and covers the executed experiment. The theoretical part contains six chapters – heat, signal, wireless router and measured climatic conditions. The practical part describes the executed experiment by thermo-camera which was used to scan wireless routers in IoT Lab in Avast Software company. Based on this experiment, the ideal position for installing the wireless router is then established. The conclusion of the practical part includes an analysis of the results of the questionnaire survey, in which technically skilled people were asked to describe the height of installation of their wireless router or whether did they consider heat and signal propagation while installing their wireless routers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Mettout, Bruno. "Interactions diamagnetiques et irradiation x d'un composite de microbilles d'etain en surchauffe supraconductrice". Paris 7, 1988. http://www.theses.fr/1988PA077118.

Texto completo

Resumen

Etude du role des interactions diamagnetiques dans la largeur de transition et de l'amplitude du signal percu lors du passage a l'etat normal des microbilles. Le comportement du composite et des boucles de lecture supraconductrices sous irradiation x permet de discuter des etats hors equilibre des supraconducteurs

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Antoine, Joseph. "Synthèse par pulvérisation cathodique de pérovskites thermochromes comme couche sélective "haute performance" d'absorbeurs solaires thermiques". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0273.

Texto completo

Resumen

Ces travaux de thèse ont porté sur l’étude du système LaCoO3 élaboré sous forme de couches minces par pulvérisation cathodique magnétron réactive. La première partie de ce travail est dédiée à l’étude des paramètres de synthèse permettant l’obtention d’un film homogène cristallin. Les influences sur la transition thermochrome des paramètres de traitement thermique et de la pression de dépôt sont discutées. Nous avons montré qu’il était possible de contrôler le rapport entre les phases cubique et rhomboédrique ainsi que la taille des cristallites en optimisant les paramètres de synthèse. Dans une seconde partie, nous avons étudié en détail les changements de propriétés de nos échantillons à l’aide du rayonnement synchrotron et de la microscopie électronique en transmission. Nos mesures ont montré que la phase cubique et la taille de cristallites influent le spin des atomes de cobalt et donc sur la nature des liaisons Co-O. Nous avons mis en évidence qu’une microstructure fine et une phase rhomboédrique augmentent l’effet thermochrome et l’amplitude optique de la transition grâce à une augmentation de la densité de population au niveau de Fermi et une diminution du gap optique
The present PhD work is focused on the study of the LaCoO3 system deposited as a thin film by reactive magnetron sputtering. The first part of this work is dedicated to the influence of the deposition parameters on the film structure. The influences of heat treatment parameters and deposition total pressure on the thermochromic transition are discussed. We have shown that it is possible to control the ratio between the cubic and rhombohedral phases as well as the size of the crystallites through the control of our parameters. In a second part, we studied in detail the properties changes using synchrotron radiation and transmission electron microscopy. Our measurements have shown that the cubic phase and the crystallites size influence the spin of cobalt atoms and therefore the nature of the Co-O bonds. We have shown that a fine microstructure and a rhombohedral phase increase the thermochromic effect and the optical switch of the transition thanks to an increase in the population density at the Fermi level and a decrease of the optical gap

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Vogt, Gilles. "Etude des phénomènes électromagnétiques dans les zones frontales des grandes machines synchrones : outils de tests sur le 125 MW". Thesis, Artois, 2013. http://www.theses.fr/2013ARTO0210/document.

Texto completo

Resumen

Cette thèse s’inscrit dans le cadre des études des phénomènes électromagnétiques dansles régions frontales des grands turbo-générateurs. L’objectif de la thèse est d’estimer apriori le champ magnétique axial en fonction du point de fonctionnement afin d’éviterles possibles dégradations du circuit magnétique (dus aux points chauds et tensions entretôles, qui sont liés à la composante axiale du champ).Une maquette à échelle réelle a été spécialement conçue et réalisée dans le but d’améliorerla compréhension physique des phénomènes : les pertes, la pénétration du champ magnétiqueet les tensions entre tôles sont analysés.Les simulations par éléments finis sont ensuite utilisées : les avantages et inconvénientsseront discutés, ainsi qu’une comparaison critique des résultats par rapport aux mesuresexpérimentales sur la maquette. La région frontale d’un turbo-alternateur est aussi entièrementmodélisée.Enfin, un modèle simple du flux axial est développé. Ses coefficients sont déterminés àl’aide de simulations par éléments finis, mais il peut ensuite être utilisé en temps réel afind’estimer le flux axial correspondant à un point de fonctionnement quelconque
This work aims to improve the knowledge of electromagnetic phenomena that occurin the end region of large turbo-generators. The goal of this work is to evaluate theaxial magnetic flux density with regard to the operating conditions (such as active orreactive power) in order to prevent potential deterioration of the stator. Indeed, the axialmagnetic field is known to induce hot points or voltages between laminations that maycause insulation breakdown and thus stator faults.An experimental apparatus in real scale has been designed and built. Its purpose is tostudy precisely the following phenomena: losses, axial magnetic flux density penetration,voltage across adjacent voltages.Finite element simulations (FEM) are also used: their advantages and drawbacks arediscussed, and the results are compared with the experimental measures. The wholeend-region of a turbo-generator is also simulated.Finally, a simple model of the axial magnetic flux is proposed. Its parameters are basedon the results of the FEM model, but it may be used in real time to evaluate the axialmagnetic flux density of any operating point

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Obrátil, Pavel. "Polyfunkční dům v Litovli". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227668.

Texto completo

Resumen

The diploma thesis was elaborated for as part of design documentation for new multifunctional building in Litovel. The building will be used for purposes of bus and train station, another way for administration purposes. The building contains the second and a third floor with a modern look suitably fits into the surrounding countryside. The significant emphasis was on both nice appearance of the building, so the correct process engineering and dispositional solution. The building is designed so that in terms of design and implementation easily accomplishable. Furthermore, to meet all the requirements for building physics and fire safety. During seminar work was solved problems of summer overheating of the room situated on the south side of the building. For the preparation of project documentation for construction was used CAD software and specialized software for structural calculations of statics and construction.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Källberg, Magnus y Rikard Bertilsson. "Klimatförändringens påverkan på inomhusklimatet och energibehovet i småhus". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-97210.

Texto completo

Resumen

Småhus byggs allt tätare och mer välisolerade för att klara de nationella målen på energieffektivisering samtidigt som klimatet beräknas bli varmare som följd av klimatförändringarna. Ett dåligt inomhusklimat kan leda till hälsoproblem och ökad dödlighet. Denna studie har som syfte att åskådliggöra hur inomhusklimatet med fokus på temperatur påverkas av klimatförändringarna i samband med val av olika byggnadstekniska lösningar för ett småhus. Studien bygger på simuleringar i programmet VIP-Energy för olika versioner av ett småhus placerat i Växjö i södra Sverige. Temperatur och energibehov sammanställdes i samband med olika klimatscenarier, energihushållningsnivåer och byggnadstekniska lösningar. Resultaten visar på att temperaturerna inomhus kan nå extrema nivåer om inte soltransmittansen begränsas och huset kyls med aktiv eller passiv kyla. Problemet förvärras när huset byggs efter striktare krav på energihushållning.
One- to two-family houses are being built to be more airtight and better insulated to meet the national goals for energy efficiency while the climate is getting warmer as a result of climate change. A poor indoor climate can lead to health problems and increased mortality rates. The purpose of this study is to illustrate how the indoor climate with a focus on temperature is affected by climate change in conjunction with the choice of different building technical solutions for a single-family house. The study is based on simulations with the VIP-Energy program for versions of a singlefamily house placed in Växjö in southern Sweden. Temperature and energy requirements were compiled in conjunction with various climate scenarios, building energy efficiency levels and building technology solutions. The results show that indoor temperatures could reach extremely high levels unless the solar transmittance is limited, and the house is cooled with active or passive cooling. The problem is exacerbated when the house is built according to stricter energy regulations.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Fahrion, Marc-Steffen. "Sommerlicher Wärmeschutz im Zeichen des Klimawandels – Anpassungsplanung für Bürogebäude". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-193732.

Texto completo

Resumen

Seit Beginn der Industrialisierung ist ein starker Anstieg der anthropogenen Treibhausgaskonzentrationen in der Atmosphäre zu verzeichnen, der zu einer Veränderung des Klimas auf der Erde führt. Schon heute sind die Auswirkungen auf die Umwelt und zahlreiche Bereiche des täglichen Lebens zu beobachten. Diese werden sich mit fortschreitendem Klimawandel noch verstärken. Auch das Bauwesen muss sich auf die sich verändernden klimatischen Einwirkungen wie beispielsweise Sommerhitze, Überflutung, Starkregen, Hagel und Wind einstellen. Für keine der genannten klimatischen Einwirkungen ist das Änderungssignal in den Klimaprojektionen so eindeutig wie für die Sommerhitze. Aus diesem Grund wird der Handlungsbedarf beim sommerlichen Wärmeschutz als besonders hoch eingeschätzt. In den westlichen Industriestaaten halten sich Erwachsene während des Sommers circa 80 % der Zeit in Innenräumen auf. Deshalb ist das Innenraumklima von entscheidender Bedeutung für die Behaglichkeit, die geistige Leistungsfähigkeit und die Gesundheit des Menschen. Wie sich der Klimawandel auf die gebaute Umwelt in Deutschland auswirkt, ist weitestgehend unerforscht. Es ist zu klären, ob nur einzelne baukonstruktive Details, die heutigen Bemessungsregeln oder sogar grundsätzliche Entwurfsprinzipien für Gebäude überdacht werden müssen. Das Ziel der Arbeit ist, eine Untersuchungsmethodik zu entwickeln, mit der die Auswirkungen des bereits beobachteten und des zu erwartenden Klimawandels auf den sommerlichen Wärmeschutz bestehender Bürogebäude beurteilt werden können. Erst dadurch lässt sich ein etwaiger Handlungsbedarf objektiv feststellen und begründen. Ein weiteres wesentliches Ziel besteht darin, beispielhafte Anpassungsmaßnahmen in Abhängigkeit der jeweiligen Baukonstruktion zu entwickeln, mit denen auch in Zukunft die sommerliche Behaglichkeit in bestehenden Bürogebäuden sichergestellt werden kann. Von besonderem Interesse ist dabei die Frage, ob baukonstruktive Maßnahmen allein in Zukunft ausreichen können oder ob zusätzlich anlagentechnische Lösungen zur technischen Kühlung unumgänglich werden. Die entwickelten Anpassungsmaßnahmen sollen die Grundlage für Gebäudekonzepte und Fassadenkonstruktionen sein, welche auch bei fortschreitendem Klimawandel die Anforderungen an die Behaglichkeit und den sommerlichen Wärmeschutz erfüllen. Des Weiteren soll eine Methode zur Bewertung der Wirtschaftlichkeit von Klimaanpassungsmaßnahmen aufgezeigt werden. Um untersuchen zu können, inwieweit die Verletzbarkeit infolge zunehmender Sommerhitze und der entsprechende Anpassungsbedarf von der Baukonstruktion abhängen, wurden drei Bürogebäude unterschiedlicher Baualtersstufen ausgewählt und mittels dynamisch-thermischer Gebäudesimulation analysiert. Die dynamisch-thermische Gebäudesimulation ist aktuell die detaillierteste Methode zur Beurteilung des sommerlichen Wärmeschutzes. Nur mit ihr können komplexe Gebäudekonzepte oder automatisierte Systeme ausreichend genau nachgebildet werden. Zur Abbildung des bereits stattgefundenen und des projizierten Klimawandels wurden fünf Klimadatensätze verwendet, mit denen der Klimawandel von der Mitte des 20. Jahrhunderts bis zum Ende des 21. Jahrhunderts dargestellt werden kann. Die Schwachpunkte der drei untersuchten Gebäude wurden analysiert und darauf aufbauend detaillierte Anpassungsvorschläge ausgearbeitet und wiederum über Simulationen bewertet. Umfangreiche Detailzeichnungen zu den angepassten Gebäudekonzepten und Fassadenkonstruktionen sollen eine Umsetzung der Ergebnisse in die Praxis erleichtern. Es werden Möglichkeiten aufgezeigt, den durch diese Maßnahmen erzielten Nutzen in Geldeinheiten zu bewerten. Dadurch können Klimaanpassungsmaßnahmen einer Wirtschaftlichkeitsbetrachtung über Investitionsrechenverfahren zugeführt werden
Since the beginning of industrialization, a large increase of anthropogenic greenhouse gas concentrations in the atmosphere has been detected. This increase is the main cause for the observed climate change. The impacts of climate change on the environment and numerous aspects of human lives have been visible and will become more and more threatening with ongoing climate change. Civil engineering has to deal with changing climate-related hazards such as summer heat, flooding, torrential rain, hail and storm. For none of the mentioned climatic impacts on buildings, the climate change signal is as unambiguous and robust as for summer heat. Thus, actions to protect from summer overheating are highly required. During summer, adults in the Western industrialized states spend about 80 % of their time indoors. Therefore, indoor climate is of essential importance for comfort, mental performance and human health. The impacts of climate change on the built environment in Germany are rarely investigated. It has to be determined whether the building construction details, current design regulations or the design principles have to be revised. This thesis aims to develop a research methodology, which evaluates the impacts of the observed and expected climate change on the protection against summer overheating of existing office buildings. Only thus a possible need for action can be objectively determined and justified. Another major objective is the development of exemplary adaptation measures for various building construction types to ensure the comfort in existing office buildings during summer. Of particular interest is the question if it will be sufficient in the future to use only passive measures or if it will be unavoidable to install technical cooling capacities. The developed adaptation measures should be the basis for building concepts and façade constructions that are able to guarantee high comfort and an improved protection against summer overheating. Furthermore, a method to evaluate the economic efficiency of adaptation measures is demonstrated. To investigate the relationship between building construction and vulnerability, three buildings of different construction year categories have been analyzed using dynamic thermal building simulations. At present, the dynamic thermal building simulation is the most detailed method for evaluating the protection against summer overheating. This is the only method which is able to reproduce complex building concepts and automated systems in sufficient detail. In order to demonstrate the impacts of the observed and projected climate change on buildings between the middle of the 20th century and the end of the 21st century, five climate datasets have been applied. The weak points of the three investigated buildings have been analyzed. Based on this, detailed adaptation measures have been developed and evaluated by thermal building simulations. Comprehensive drawings, which show the adapted building concepts and façade details, will facilitate the application in practice. Different possibilities are demonstrated to express the achieved benefit from the adaptation measures in monetary units. Therefore, adaptation measures can be assessed by investment calculations

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Blot, Joseph. "Relation entre les grandeurs supraconductrices caracteristiques de l'aluminium massif et les champs de transition de films divises, en fonction de leur epaisseur". Rennes, INSA, 1987. http://www.theses.fr/1987ISAR0006.

Texto completo

Resumen

Etude de l'influence de la taille des echantillons sur les champs magnetiques de surchauffe et de retard a la condensation dans l'etat supraconducteur sur des couches d'aluminium divisees en damiers et dont le refroidissement est assure dans un dispositif cryogenique a helium liquide permettant d'atteindre 0,37k. Analyse systematique en fonction de la temperature et de l'epaisseur, des champs paralleles et perpendiculaire de transition presentes par une serie de films evapores sur des substrats de verre a la temperature ambiante

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Machard, Anaïs. "Towards mitigation and adaptation to climate change : Contribution to Building Design". Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS020.

Texto completo

Resumen

Compte tenu de l’augmentation de la fréquence des canicules, il est nécessaire de s’assurer que les bâtiments conçus et construits aujourd’hui seront adaptés aux futures températures plus élevées. Le périmètre de cette thèse consiste à proposer une méthodologie de contribution à la conception des bâtiments considérant à la fois les enjeux d’atténuation (réduction des besoins énergétiques) et d’adaptation (confort thermique estival, réduction du risque sanitaire en période de canicule) au changement climatique. La méthodologie a pour vocation d’être adaptable à différents types de bâtiments et de climats. Dans ce but, nous avons développé des fichiers météorologiques contenant des séquences typiques, ainsi que des vagues de chaleur futures. Par la suite, des méthodes d’analyse de sensibilité et d’optimisation couplées à des simulations thermiques dynamiques du bâtiment ont permis d’évaluer le potentiel de différentes techniques de rafraîchissement passif utilisées pour diminuer la surchauffe d’été en climats futurs. Les résultats de ces travaux de recherche mettent en évidence que les stratégies évaluées sont efficaces pour maintenir un confort thermique estival lors des étés futurs types à Paris et à La Rochelle. Cependant, à Carpentras, pour un été type futur, et pour ces trois villes en périodes de canicules futures récurrentes, les limites de ces solutions sont mises en exergue. En effet, les résultats de l’étude montrent que les occupants sont exposés à la chaleur lors de plusieurs jours consécutifs au-dessus de seuils à la fois diurnes et nocturnes ce qui résulte en un risque sanitaire pour les personnes vulnérables. Ces séquences ne sont pas détectées en utilisant des fichiers futurs types uniquement, ce qui démontre la pertinence de ces travaux. La combinaison d’enveloppes de bâtiments optimisées, de stratégies de rafraîchissement et d’adaptation des occupants se révèle être nécessaire afin d’atténuer le risque sanitaire récurrent auguré pour le milieu du siècle en France
Due to climate change projecting increased heatwaves occurrence, ensuring that buildings designed and built today will be adapted to future warmer temperatures is essential. The scope of this Ph.D. is to propose a methodological contribution to the design of buildings that both mitigate (minimize yearly energy needs) and adapt (minimize summer indoor overheating, limit health-heat-related risk) to climate change. The methodology can be applied to any building case study in any climate. For this purpose, bias-adjusted weather files containing both present, future typical conditions and future heatwave periods were developed. The potential of different passive cooling mitigation and adaptation strategies to reduce summer indoor overheating is evaluated using these weather files through dynamic thermal simulations, sensitivity analysis and optimization methods. The results of this research work highlight that for the building case study, the evaluated strategies (buffer spaces, thermal mass, roof optical properties, glazing ratio, ventilative cooling) have a strong capacity to enable summer thermal comfort in future typical summers in Paris and in La Rochelle. However, in Carpentras, and under recurring heatwaves in all three cities, the limits of these mitigation and adaptation measures are recognized. In fact, the future heatwaves consistently lead to consecutive days of indoor overheating exposure during both daytime and nighttime for building occupants, leading to a health-heat-related risk especially for the most vulnerable. These sequences are not detected when using only future typical years, which stresses the relevance of this work. Only the combination of optimized building envelopes, ventilative cooling strategies and adaptive opportunities from building occupants (solar control, increased indoor air velocities) have the potential to offset the projected recurring health-heat-related risk, particularly elevated in the South of France

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Pellan, Yves. "Etude de la metastabilite de la transition supraconductrice de films divises d'indium sous champ magnetique parallele et perpendiculaire". Rennes, INSA, 1987. http://www.theses.fr/1987ISAR0007.

Texto completo

Resumen

Mesures systematiques des champs de surchauffe et de retard a la condensation et du champ critique thermodynamique du film en fonction de l'epaisseur, de la temperature et de l'orientation du champ magnetique, sur deux series de films deposes sur des substrats a 295k et 77k. Determination de la profondeur de penetration, de la longueur de coherence et du parametre de ginzburg-landau de l'indium supraconducteur pur

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Němeček, Martin. "Vliv vnitřní tepelné akumulace konstrukcí pasivních domů na jejich letní tepelnou stabilitu". Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390267.

Texto completo

Resumen

In recent years we may observe a growth in construction of passive houses and low energy houses using lightweight constructions such as modern wooden houses. It is assumed that wooden houses keep overheating more comparing to brick houses during summer period. Due to the lack of research in this field the paper investigates the influence of internal thermal storage mass in passive houses constructions on their summer thermal stability under the Czech climatic conditions. Only sensible heat accumulation without a usage of phase change materials is examined. Differences between wooden houses comparing to brick-built houses are emphasized. Objects of research are mostly residential passive houses in low energy building standards. However, the results of research might be applied to different types of buildings as well. The first section outlines theoretical fundamentals. For the research itself various scientific research methods were used, such as basic mathematical calculations, experimental temperature measurement of two buildings (detached house in Dubňany and in Moravany) and numerical simulations. Own tribute to the research was first of all discussion on the topic of thermal accumulation and structures heat capacity calculation. Experimental measurements outlined conclusive evidence about the importance of internal thermal storage mass in respect of interior summer overheating. The research confirmed that the highest interior temperature reached is mostly influenced by solar gains through unshaded windows. However, the influence of internal thermal storage mass is not remote. If we compare standard timber-framed wooden house to the hole ceramic bricks-built house, the wooden house will overheat by 0,5°C more during a standard day. Wider spread in the maximum temperature reached was measured for lightweight consturctions wooden houses without any internal thermal storage mass. Therefore, such structures should have an additional layer of thermal storage mass.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Almeida, Francisco Lima. "Energy Efficiency of Buildings: Solutions to Decrease the Overheating of a School Building". Master's thesis, 2019. https://hdl.handle.net/10216/121180.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Li, Chien-Hsing y 李建興. "Flow and Heat Transfer Simulation in an Electric Control Box to Impair the Overheating Problem". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/42975999720556002004.

Texto completo

Resumen

碩士
國立中興大學
機械工程學系所
102
Abstract At present, there are two major types of cooling methods applied on actuator of CNC machine’s generator: internal air cooling system and external air cooling system. The object of this research is external air cooling system using Ansys Fluent simulation and experimental verification methods to improve the cooling efficiency of the sub electric box, which can avoid operating temperature of driver in the main electric box be affected by poor cooling efficiency of the sub electric box. Overall dimension of the electric box is 820mm width x 1560mm height x 450mm depth equipped with a sub electric box of 820mm width x 926mm height x 165mm depth. The original heat dissipation design is based on atmospheric displacement. Three axial fans operating in parallel and a row (10pcs) of air intake connect with environment. Via the experimental measurements it is noted that all heat sink surfaces inside the sub electric box, except W-axis heat sink, are more than 40℃ degree with highest of 64.9℃ of Spindle driver heat sink. Poor cooling causes surface temperature of driver of main electric box more than 50℃ degree, and surface temperature of driver’s internal parts is even higher than 55℃degree. There are eight improvement proposals addressed in this research purpose to discuss and resolve the situation of high temperature mentioned above. Eventually, increasing the numbers of vent at entrance and increasing coefficient of heat convection of heat sink are the most efficient ways to improve the situation of high temperature of heat sink. Among them, proposal 5、6 and 8 all can keep the surface temperature of heat sink lower than 40℃, and keep the surface temperature of driver lower than 50℃.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Ingegneria, Sara Ticci Facoltà Di, Frida Bazzocchi, Vincenzo Di Naso y Andrea Rocchetti. "Sustainable refurbishment method for industrialized public residential buildings in the mediterranean climate". Doctoral thesis, 2016. http://hdl.handle.net/2158/1103546.

Texto completo

Resumen

The suburbs of most Italian cities particularly feel this need of restoration. The immense quantity of public housing built from the '60s to the '80s, in response to a pressing need to create housing quickly and with limited financial resources, is now in urgent need of redevelopment both from the energy performance point of view and for increasing the poor internal comfort conditions. The research defines a sustainable refurbishment method for public residential buildings made with industrialized techniques in the Mediterranean climate, starting from the results obtained by the application of renovation strategies to some sample buildings built with these construction methods during the ‘60s-‘80s, located in the Florence area. Two building complexes are analysed: COMPLEX A located in Prato consisting of 2 buildings and COMPLEX B located in Firenze involving 4 buildings.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Oberholzer, Phillip Johannes. "Best practices for automation and control of mine dewatering systems / Phillip Johannes Oberholzer". Thesis, 2015. http://hdl.handle.net/10394/15483.

Texto completo

Resumen

Typical deep level mines use up to 27 ML water per day for mining operations. Multistage centrifugal pumps up to 2500 MW are used in an upward cascading manor to dewater the shaft. The dewatering systems at some mines are automated to enable surface control. Automation of the pumps is typically based on the best practice procedure known when implemented. Best practice procedures are used to ensure safe pumping operations. It was found that pump failures could still occur even with the best practice implemented. Unexpected failures of pumps are of major concern because they can result in the flooding of a mine. Flooding increases the risk of environmental damage and injury to the mining personnel. An additional concern is the maintenance cost of multistage centrifugal pumps. Overhaul cost of a seized multistage centrifugal pump is almost R1-million. The aim of this study was to improve established best practice procedures for pump automation. This could be achieved by investigating the general root cause of failures of automated pumps. Additional instrumentation and protection devices to prevent similar incidents were examined. Revised system control parameters were developed to ensure that the pumps operated within the design specifications. The improved best practices proved to prevent failures as a result of overheating and cavitation. Increasing the pump reliability and availability enabled surface control. The control of the automated dewatering system realised an electricity cost saving of R6-million. The automated system also made it possible to calculate the real-time pump efficiency within 5%. Previous best practice procedure was found to be inadequate to prevent all possibilities of failure. Additional precaution measurements were added to prevent pump failure.
MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Overheating"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros