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Von, Backstrom Theodor W. "From turbo-machines to solar chimneys." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71762.
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Thesis (PhD)--Stellenbosch University, 2012.ENGLISH ABSTRACT: This dissertation is basically a summary, with some interpretation, of published research by the author. The scope is limited to the fields of turbo-machinery, computational fluid dynamics and solar chimney power plants. The main contribution in the field of turbo-machinery in general is in the development of a through-flow method that automatically satisfies mass conservation. Concerning fan design, the contributions are the realization of the importance of the exit kinetic energy in the determination of the efficiency of rotor-only axial flow fans, and the quantification of the effect of off-axis inflow into cooling system fans on their performance. In the field of centrifugal fans and compressors an original, unifying model for the prediction of slip factor was developed. To investigate accident scenarios in closed cycle gas turbine nuclear reactors, all possible operational modes of multi-stage axial compressor operation caused by flow and rotation direction were investigated experimentally and computationally. Spanning the fields of turbo-machinery and solar chimneys, the basic theory of solar chimney turbines was developed, showing that high turbine efficiency was possible. In the field of solar chimneys, an original thermodynamic approach was developed to predict the main relationships that govern solar chimney performance, and to solve the through-flow equations for non-ideal systems with losses. Equations for the accurate determination of all the thermodynamic variables in a solar chimney as dependent on chimney height, wall friction, additional losses, internal drag and area change were derived and solved. Coefficients of wall friction, bracing wheel loss and exit kinetic energy were determined experimentally, and empirical equations were developed to predict the loss coefficient of the collector to turbine transition section and and the turbine inlet flow angle. A simple power law approach allowed the calculation of the optimal turbine pressure drop in solar chimney power plants. A comparison of two sets of equations used to calculate the heat fluxes into, inside and leaving the solar collector, resulted in similar air temperature rises in the collector, and similar produced power. It turned out however that the optimal flow for minimal turbine pressure drop was dependent on the heat transfer models. Investigation of the performance of various solar chimney turbo-generator layouts using analytical models and optimisation techniques showed that the optimal number of turbines varies with plant size, but the individual turbine size, the number of blades and even the efficiency remains close to constant. It was found that the cost of a turbogenerator system, however, varies significantly with size. A joint paper with several German universities and institutions did a comparative cost analysis of solar chimney power plants
AFRIKAANSE OPSOMMING: Hierdie verhandeling is basies ’n opsomming, met interpretasie, van gepubliseerde navorsing deur die outeur. Die omvang is beperk tot die gebiede van turbomasjinerie, berekeningsvloeidinamika en sonskoorsteenkragstasies. Die hoof bydrae op die gebied van turbomasjinerie in die algemeen is in die ontwikkeling van ’n deurvloeimetode wat outomaties massabehoud bevredig. Wat waaierontwerp betref is die bydrae die besef van die belangrikheid van die uitlaat kinetiese energie in die bepaling van waaierbenuttingsgraad, en die kwantifisering van die effek van af-as invloei in verkoelingswaaiers op hulle gedrag. Op die gebied van sentrifugaalwaaiers en -kompressors is ’n oorspronklike, samevattende model vir die voorspelling van glipfaktor ontwikkel. Om ongeluk-scenario’s in geslote kringloop gasturbine kenreaktors te ondersoek is al die moontlike werksmodusse veroorsaak deur vloei en rotasie rigting van ’n multistadium aksiaalkompressor eksperimenteel en numeries ondersoek. As brug tussen turbomasjinerie en sonskoorstene is die basiese teorie van sonskoorsteenturbines ontwikkel met die aanduiding dat hoë turbine benuttingsgraad moontlik is. Op die gebied van sonskoorstene is ’n oorspronklike termodinamies benadering ontwikkel om die hoofverwantskappe te voorspel wat sonskoorsteen gedrag bepaal, en om die deurvloei vergelykings op te los vir nie-ideale stelsels met verliese. Vergelykings vir die akkurate bepaling van al die termodinamiese veranderlikes in ’n sonskoorsteen soos afhanklik van skoorsteenhoogte, wandwrywing, bykomstige verliese, interne sleur en oppervlakte verandering is afgelei en opgelos. Koëffisiënte vir wandwrywing, verstywingswiel-verlies en uitlaat kinetiese energie is eksperimenteel bepaal, en empiriese vergelykings is ontwikkel om die verlieskoëffisiënt van die kollektor-tot-skoorsteen oorgang en die turbine inlaatvloeihoek te bepaal. ’n Eenvoudige magswet benadering het dit mootlik gemaak om die optimum turbine-drukval in sonskoorsteen aanlegte te bepaal. ’n Verglyking van twee stelle vergelykings om warmtevloede in, binne en uit die sonkollektor te bereken het gelei na soortgelyke temperatuurstygings en gelewerde drywing. Die optimale vloei vir maksimum drywing was egter afhanklik van die warmteoordrag modelle. Ondersoek van die gedrag van verskeie turbo-generator uitlegte, deur gebruik van analitiese modelle en optimeringstegnieke het getoon dat die optimale aantal turbines wissel met aanleg grootte, maar die individuele turbine grootte, die aantal lemme en selfs die benuttingsgraad bly feitlik konstant. Daar is egter gevind dat die koste van ’n turbogenerator stelsel beduidend wissel met grootte. ’n Gesamentlike artikel met verskeie Duitse universiteite en instansies het ’n vergelykende koste analise van sonskoorstene gedoen.
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Hassanain, Ahmed A. "Investigation of solar chimneys and tubular transpired solar air heaters as improved systems for solar dryers." Thesis, University of Ulster, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393770.
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Heisler, Elizabeth Marie. "Exploring Alternative Designs for Solar Chimneys using Computational Fluid Dynamics." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/52572.
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Solar chimney power plants use the buoyancy-nature of heated air to harness the Sun's energy without using solar panels. The flow is driven by a pressure difference in the chimney system, so traditional chimneys are extremely tall to increase the pressure differential and the air's velocity. Computational fluid dynamics (CFD) was used to model the airflow through a solar chimney. Different boundary conditions were tested to find the best model that simulated the night-time operation of a solar chimney assumed to be in sub-Saharan Africa. At night, the air is heated by the energy that was stored in the ground during the day dispersing into the cooler air. It is necessary to model a solar chimney with layer of thermal storage as a porous material for FLUENT to correctly calculate the heat transfer between the ground and the air. The solar collector needs to have radiative and convective boundary conditions to accurately simulate the night-time heat transfer on the collector. To correctly calculate the heat transfer in the system, it is necessary to employ the Discrete Ordinates radiation model. Different chimney configurations were studied with the hopes of designing a shorter solar chimney without decreases the amount of airflow through the system. Clusters of four and five shorter chimneys decreased the air's maximum velocity through the system, but increased the total flow rate. Passive advections wells were added to the thermal storage and were analyzed as a way to increase the heat transfer from the ground to the air.Master of Science
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Charitar, Deepti. "Numerical study of the thermal performance of solar chimneys for ventilation in buildings." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20100.
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Building ventilation is crucial for improving the indoor air quality and thermal comfort. Nowadays, mechanical ventilation systems such as air conditioning and fans are most commonly used in buildings. However, these devices consume a lot of electricity which is mainly generated from the combustion of fossil fuels, resulting in the release of greenhouse gases and thereby contributing to climate change. Consequently, it is essential to switch to natural ventilation systems which are environmentally friendly as they are based on renewable sources of energy. One such type of natural ventilation system is the solar chimney which can either be roof-mounted or wall-mounted in buildings. The aim of this study was to develop a mathematical model for assessing the thermal performance of roof-mounted (inclined) and wall-mounted (vertical) solar chimneys. The model was validated using numerical simulations in MATLAB. Different configurations of solar chimneys were designed and modelled in MATLAB in order to compare their performances, in terms of the ventilation rate expressed as the number of air changes per hour, ACH. Raw climatic data, including the intensities of global and diffuse solar radiation on a horizontal plane, wind speed and ambient temperature were obtained for Stellenbosch, located in the Western Cape Province of South Africa. This was used for the MATLAB modelling of the solar chimneys. The effects of inclination angle, air gap, chimney height and view factor on the thermal performance of solar chimneys were explored in this study.
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Swainson, M. J. "Evaluation of the potential of solar chimneys to drive natural ventilation in non domestic buildings." Thesis, Cranfield University, 1997. http://hdl.handle.net/1826/3967.
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The solar chimney allows natural ventilation to be achieved during periods
when the wind velocities are low and the difference between internal and
external air temperatures is minimal. The correct design of such building
components requires that designers have appropriate design tools available to
them that are both effective and easy to use. The aim of this project was to
evaluate design tools currently available and if appropriate to provide a tool
that would allow the effects of variations in key physical parameters to be
evaluated.
Two design tools are currently available to designers; zonal models and CFD
programmes. Both of these were however found to be unsuitable for the
evaluation of the performance of a solar chimney. Zonal models assume that
the air within a zone is fully mixed which results in the effects of variations in
physical parameters on the mass flow rate being incorrectly predicted. CFD
programmes require validation of any models developed before confidence in
the predictions can be established, it was found however that data for such
validation was not available for realistic flow configurations.
An experimental rig was designed and tested to ensure that the uncertainty in
the data produced was both minimised and accurately quantified.
A detailed review of the sensitivity of a CFD programme to model and input
variables was undertaken allowing development of an appropriate model.
Comparison of the results of the experimental investigation and CFD
predictions showed that the CFD programme, utilising the ke turbulence
model accurately predicted air flow rates through a solar chimney across a
range of key physical parameter variations.
Within the limits of the validity determined for the CFD model, a detailed
parametric investigation was then undertaken.
The result of the parametric investigation was the development of a design tool
appropriate for the determination of the effects of variations of the key physical
variables on the mass flow rate through a solar chimney.
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Beviss-Challinor, Lauren Margaret. "Design, build and test a passive thermal system for a loft : a roof solar chimney application for South African weather conditions." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/348.
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Thesis (MEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2007.ENGLISH: The design, construction and testing of a passive thermal system, a roof solar chimney, for a loft is considered. Unlike conventional solar chimneys the solar collector is constructed from corrugated iron roof sheets with the aim that it can be integrated into existing buildings at a lower cost or used in low cost housing developments. The main objective of the study was to determine the feasibility of such low-cost design to regulate thermal conditions in a loft, that is heating the loft during winter and enhancing natural ventilation during summer, by carrying out an experimental and analytical study. The results obtained from the experimental study showed that for winter the solar chimney, having a channel width, depth and length of 0.7 m, 0.1 m and 1.8 m respectively and with a peal solar radiation of 850 W/m², heated the room air 5°C higher than the ambient temperature during the hottest periods of the day, which is only marginally better than a loft with conventional roof insulation. At night, it was found that reverse airflow occurred through the chimney, cooling the loft down to ambient temperature, due to radiation heat loss from the roof collector to the night sky. For summer operation, the experimental data showed that the chimney was able to maintain the loft at ambient temperature and the analytical study found that the chimney was able to enhance natural ventilation effectively, reaching air exchange rate of 6.6 per hour for the 4.6 m³ volume space. It was also found that the chimney’s performance dropped rapidly and significantly during periods of low solar radiation and at night. A sensitivity analysis illustrated that for both summer and winter operation, the size, tilt angle and absorptivity of the roof collector greatly effected the efficiency and mass flow rates of the system, agreeing well with other literature. These results prove that this low cost solar chimney cooling design was feasible to enhance natural ventilation mainly during hot summer conditions with high solar radiation. Compared to a loft with only conventional roof insulation, the chimney did not perform effectively during the winter to heat the loft up, meaning that winter operation for this specific design is not feasible. Possible improvements to the design include using construction materials with higher thermal capacities to retain heat energy and ensure continued operation during periods of low solar radiation, as well as using selective absorber coatings on the collector surface. It is recommended that further work on the project include the integration of these improvements into the present design and to use the findings obtained from the sensitivity analysis to improve system efficiencies. CFD analysis of the test-rig will be insightful as an additional means to validate and compare with the analytical and experimental data obtained in this report. With the continuation of these studies, this low-cost solar chimney design can be optimised, validated on a commercial scale and built into existing and new housing developments. Incorporating such a passive thermal device will aid homeowners in air regulation and thermal comfort of their living space as well as saving on energy requirements.
Sponsored by the Centre for Renewable and Sustainable Energy Studies, Stellenbosch University
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Gannon, Anthony John. "Solar chimney turbine performance." Thesis, Stellenbosch : University of Stellenbosch, 2002. http://hdl.handle.net/10019.1/1402.
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Thesis (PhD (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2002.This project investigates the performance of solar chimney power plant turbines. A solar chimney power plant consists of a tall chimney surrounded by a transparent deck or solar collector. The sun heats the air in the collector through the greenhouse effect. A turbine extracts energy from the hot air rising up the chimney. An investigation of the requirements and operation of such turbines is needed. Correct matching of the turbine to the plant requires the determination of the turbine operational range and other requirements. An air-standard cycle analysis is extended to include component and system losses. Simple steady-state and transient collector models are added to take into account the coupling effect of the collector air temperature rise and mass flow rate on the turbine operation. The predicted turbine operational range for a representative day shows that the expected pressure drop in a full-scale solar chimney turbine is significantly higher than has previously been predicted. A turbine design method is developed and used to design a turbine for the representative day. The methods can easily be extended to include more operating points for a full year of operation. A turbine layout is suggested that uses the chimney support pillars as inlet guide vanes (IGVs). These introduce pre-whirl to the turbine and reduce the amount of exit whirl thus decreasing the kinetic energy at the turbine exit. Non-radial inlet guide vanes add to the torsional stiffness of the chimney base. A matrix throughflow method is used to design the radial to axial duct between the IGVs and rotor. The turbine blade profiles are simulated using a surface-vortex method. This is coupled to an optimisation scheme that minimises both the chord length and maximum flow velocity of the profile to reduce blade drag. An experimental program investigates the performance of the turbine. Volume flow, pressure drop, torque and speed are measured on a scale model turbine to map the turbine performance over a wide range. The velocity and pressure profiles are measured at two design points to investigate the flow through the turbine in more detail. These are compared to the design predictions and used to improve the design method. The experiments show that the design of a solar chimney turbine with a total-to-total efficiency of 85 % - 90 % and total-to-static efficiency of 75 % - 80 % is possible. Analysis of the experimental results shows that the turbine efficiency can be improved.
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Gannon, A. J. "Solar chimney turbine performance /." Link to the online version, 2002. http://hdl.handle.net/10019/1526.
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Paez, Ortega Elias. "Analyzes of Solar Chimney Design." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14000.
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The aim of this work to study the solar chimney installed in the EPT-lab of the NTNU. The work starts with the development of a CFD model of the solar chimney and comparing with the experimental data, showing a good accuracy of the CFD results. The CFD model is used to compare three types of solar chimneys for different heights and width; obtained that the chimney installed in the EPT-lab gets higher flow rates in the most of the most of the cases. The CFD model shows a uniform temperature and velocity inside the chimney that allows developing a simple physical model of the chimney, which gives a good precision of results. Finally a simplification of the solar chimney and other systems installed in a building is simulated and also is developed another physical model for this kind of building, giving an idea of the behavior of this solar house in diverse conditions.
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Rousseau, Jean-Pierre. "Dynamic evaluation of the solar chimney." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1184.
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Kirstein, Carl. "Flow through a solar chimney power plant collector-to-chimney transition section." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/21372.
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Thesis (MScIng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: One of the areas of the fluid dynamic design of solar chimney power plants that has not been investigated sufficiently is the collector-to-chimney transition section of a single turbine layout. The transition section contains the turbine inlet guide vanes (IGVs) that support the whole chimney and guide the flow entering the turbine. The primary objective of the study was to determine the dependence of the loss coefficient of the section on inlet guide vane stagger angle and collector roof height. Experiments were done on a nominal 900 mm chimney diameter rig, with four combinations of two collector roof heights and two IGV stagger angles. Velocity components and pressures in the transition section were measured in three conical planes, respectively at the IGV exit and midway to, and just below the turbine position, using a five-hole pneumatic pressure probe. Very good agreement was found between experimental values and commercial CFD code predictions of flow angles, velocity components and internal and wall static pressures. The agreement between measured and predicted total pressure loss coefficient was reasonable when considering that most of the loss occurred in the weak wakes of the IGVs and in the very thin transition section wall boundary layers. The CFD code served to extend the predictions to a proposed full scale geometry. The losses are less than previously assumed. The study led to correlations between respectively loss and turning angle as dependent variables, and collector roof height and IGV stagger angle as independent variables.
AFRIKAANSE OPSOMMING: Een van die gebiede van vloeidinamiese ontwerp van sonskoorsteen kragstasies wat nog nie voldoende navorsing geniet het nie is die kollektor-tot-skoorsteen oorgangs gedeelte van `n enkel turbine opstelling. Die oorgangs gedeelte bevat die turbine se inlaat lei lemme (ILL) wat die hele skoorsteen dra en die vloei lei wat by die turbine ingaan. Die hoof doel van hierdie studie was om die verlies koëffisiënt van hierdie oorgangs gedeelte te bepaal as afhanklike van die ILL stel hoek en die hoogte van die kollektor se dak hoogte. Die eksperimente het op `n nominale 900mm deursnee skoorsteen skaal model geskied, met vier kombinasies van twee dak hoogtes en twee ILL stel hoeke. Snelheidskomponente en drukke is met `n pneumatiese 5-punt buis in drie koniese vlakke in die oorgangs gedeelte gemeet. Die vlakke was by die ILL se stert, halfpad deur die oorgangs gedeelte en by die turbine se inlaat. Baie goeie ooreenstemming is gevind met die eksperimentele waardes en `n kommersiële CFD kode se voorspellings van vloei hoeke, snelheidskomponente en interne- en wand statiese drukke. Die ooreenstemming tussen die gemete waardes en die berekende waardes vir die totale druk verlies koëffisiënt was redelik siende dat die meeste verliese van die klein versteurings van die ILL en die oorgangs gedeelte se dun-wand grenslae kom. Die CFD kode is toe ingespan om verdere voorspellings te maak vir `n voorgestelde volskaal geometrie. Die verliese is minder as wat daar van te vore voorspel is. Hierdie studie het gelei tot korrelasies tussen onderskeidelik verlies en draai hoeke as afhanklike veranderlikes, en kollektor dak hoogte en ILL plasings hoek as onafhanklike veranderlikes.
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Cottam, P. J. "Innovation in solar thermal chimney power plants." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10045417/.
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This thesis analyses novel technology for renewable electricity generation: the solar thermal chimney (STC) power plant and the suspended chimney (SC) as a plant component. The STC consists of a solar collector, a tall chimney located at the centre of the collector, and turbines and generators at the base of the chimney. Air heated in the collector rises up the chimney under buoyancy and generates power in the turbines. STCs have the potential to generate large amounts of power, but research is required to improve their economic viability. A state-of-the-art STC model was developed, focussing on accurate simulation of collector thermodynamics, and providing data on flow characteristics and plant performance. It was used to explore power generation for matched component dimensions, where for given chimney heights, a range of chimney and collector radii were investigated. Matched dimensions are driven by the collector thermal components approaching thermal equilibrium. This analysis was complemented with a simple cost model to identify the most cost-effective STC configurations. The collector canopy is an exceptionally large structure. Many of the designs proposed in the literature are either complex to manufacture or limit performance. This thesis presents and analyses a series of novel canopy profiles which are easier to manufacture and can be incorporated with little loss in performance. STC chimneys are exceptionally tall slender structures and supporting their self-weight is difficult. This thesis proposes to re-design the chimney as a fabric structure, held aloft with lighter-than-air gas. The performance of initial, small scale suspended chimney prototypes under lateral loading was investigated experimentally to assess the response to wind loads. A novel method of stiffening is proposed and design of larger prototypes developed. The economic viability of a commercial-scale suspended chimney was investigated, yielding cost reductions compared to conventional chimney designs.
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Hedderwick, Richard Anthony. "Performance evaluation of a solar chimney power plant." Thesis, Stellenbosch : University of Stellenbosch, 2000. http://hdl.handle.net/10019.1/1983.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2000.A solar chimney power plant consists of a central chimney that is surrounded by a transparent canopy located a few meters above ground level. The ground beneath this canopy or collector as it is known is heated by the solar radiation that is effectively trapped by the collector. This in turn heats the air in the collector, which flows radially inwards towards the chimney. This movement is driven by the difference between the hydrostatic pressure of the air inside- and outside the solar chimney system. The energy is extracted from the air by a turbine driven generator situated at the base of the chimney. The performance of such a solar chimney power plant is evaluated in this study making use of a detailed mathematical model. In this model the relevant discretised energy and draught equations are deduced and solved to determine the performance of a specific plant referred to as the "reference plant". This plant is to be located at a site near Sishen in the Northern Cape in South Africa where meteorological data is available. The performance characteristics of this plant are presented using values from the 21 st of December as an example. These characteristics include the instantaneous and integrated power output, as well as the absorption of the solar radiation of each of the parts of the collector. The air temperatures throughout the plant and the convective heat transfer coefficients in the collector in the region of developing and fully developed flow are presented. The pressure of the air throughout the system is presented as well as the pressure drop over the turbine. Temperature distributions in the ground below the collector are also presented and discussed.
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Van, Dyk Cobus. "The realisation of the solar chimney inlet guide vanes." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50175.
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Thesis (MScEng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: Up to this point in time research on the South African solar chimney, proposed for a site in the Northern Cape, comprised of determining the structural integrity of the chimney structure, as well as airflow calculation, finding the optimal shape for the airflow channels. Not much work had been done on the realisation of the foundation of the global structure, i.e. how the cardinal parts are optimized in an integrated system. The inlet guide vanes (IGV's) should be central in such research efforts, being the main support of gravitational and lateral wind load on the chimney structure, as well as its important role in channelling air and creating pre-swirl of the airflow onto the turbine blades. However, little detailed research - research to actually determine and fix the many variables of the IGV's and integration with surrounding parts - had been performed! In this thesis as many of these variables as possible are investigated - ranging from structural integrity with regard to compressive and shear strength through optimizing structure eigenfrequency to economic feasibility. The outcome of this study is conceptual solutions regarding the geometry of the IGV structures in order for it to support the chimney while minimizing material volume. Finite element methods are used to create insight into the behaviour of the IGV's and force transferring structures, incorporating external factors such as lateral wind and gravitational loadsto determine the optimal shape of these structures. This study is valuable for researchers on the solar chimney, serving as a reference from where to design and secure the variables of the global structure, and eventually building the solar chimney. Keywords: Solar chimney, inlet guide vanes, solar power, massive concrete structures, structural realisation, finite element application, structure optimisation.
AFRIKAANSE OPSOMMING: Tot op hede het die navorsing op die Suid Afrikaanse sonskoorsteen, wat beplan word vir konstruksie in die Noordkaap, bestaan uit die bepaling van die integriteit van die struktuur asook lugvloei berekeninge om die optimale vorm van die lugvloei kanale te lewer. Min werk is gedoen om die fondasies van die globale struktuur, dus hoe die kardinale dele geïntegreer is in die gesamentlike sisteem, te ondersoek. Die inlaat lei lemme behoort sentraal te lê in sulke navorsingspogings aangesien dit die hoof ondersteuner en verspreider van gravitasie en laterale windlaste op die skoorsteen struktuur is. Dit speelook 'n integrale rol in die kanalisering van invloeiende lug om dit vooraf 'n vorteks beweging te gee vir 'n optimale invalshoek op die turbine lemme. Min gedetaileerde navorsing - navorsing om die verskeie onbekende faktore rondom die inlaat lei lemme en die omliggende strukture te bepaal - is tot op hede gedoen. Hierdie tesis mik om soveel moontlik van hierdie veranderlikes - wat reik van struktuur integriteit met betrekking tot die samedrukkings- en skuifsterktes in die materiaal tot die eie-frekwensies en ekonomiese vatbaarheid van die struktuur - vas te stel. Die uitkoms van hierdie studie is konseptueie oplossings vir die geometrie van die inlaat lei lem strukture wat terselfdertyd die totale struktuur se materiaal volume minimiseer. Eindige element metodes word gebruik om insig in die gedrag van die inlaat lei lemme en ander strukture wat krag oordra, te genereer. Die metodes inkorporeer soveel as moontlik van die eksterne faktore soos gravitasie en laterale windlas om die optimale geometrie vir die betrokke struktuur te bepaal. Hierdie studie is waardevol vir navorsers oor die sonskoorsteen en dien as 'n bron waaruit verdere ontwerp en die vasstel van veranderlikes in die globale struktuur gedoen kan word met die oog op die uiteindelike daarstelling van 'n sonskoorsteen.
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Park, David. "The Application of the Solar Chimney for Ventilating Buildings." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/73418.
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This study sought to demonstrate the potential applications of the solar chimney for the naturally ventilating a building. Computational fluid dynamics (CFD) was used to model various room configurations to assess ventilation strategies. A parametric study of the solar chimney system was executed, and three-dimensional simulations were compared and validated with experiments. A new definition for the hydraulic diameter that incorporated the chimney geometry was developed to predict the flow regime in the solar chimney system. To mitigate the cost and effort to use experiments to analyze building energy, a mathematical approach was considered. A relationship between small- and full-scale models was investigated using non-dimensional analysis. Multiple parameters were involved in the mathematical model to predict the air velocity, where the predictions were in good agreement with experimental data as well as the numerical simulations from the present study.
The second part of the study considered building design optimization to improve ventilation using air changes per hour (ACH) as a metric, and air circulation patterns within the building. An upper vent was introduced near the ceiling of the chimney system, which induced better air circulation by removing the warm air in the building. The study pursued to model a realistic scenario for the solar chimney system, where it investigated the effect of the vent sizes, insulation, and a reasonable solar chimney size. It was shown that it is critical to insulate the backside of the absorber and that the ratio of the conditioned area to chimney volume should be at least 10.
Lastly, the application of the solar chimney system for basement ventilation was discussed. Appropriate vent locations in the basement were determined, where the best ventilation was achieved when the duct inlet was located near the ceiling and the exhaust vent was located near the floor of the chimney. Sufficient ventilation was also achieved even for scenarios of a congested building when modeling the presence of multiple people.Ph. D.
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Tavakolinia, Fereshteh. "Wind- Chimney (Integrating the Principles of a Wind-Catcher and a Solar-Chimney to Provide Natural Ventilation)." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/678.
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WIND-CHIMNEY
Integrating the principles of a wind-catcher and a solar chimney to provide natural ventilation
Fereshteh Tavakolinia
Abstract
This paper suggests using a wind-catcher integrated with a solar-chimney in a single story building so that the resident might benefit from natural ventilation, a passive cooling system, and heating strategies; it would also help to decrease energy use, CO2 emissions, and pollution. This system is able to remove undesirable interior heat pollution from a building and provide thermal comfort for the occupant.The present study introduces the use of a solar-chimney with an underground air channel combined with a wind-catcher, all as part of one device. Both the wind-catcher and solar chimney concepts used for improving a room’s natural ventilation are individually and analytically studied. This paper shows that the solar-chimney can be completely used to control and improve the underground cooling system during the day without any electricity. With a proper design, the solar-chimney can provide a thermally comfortable indoor environment for many hours during hot summers. The end product of this thesis research is a natural ventilation system and techniques that improve air quality and thermal comfort levels in a single story building. The proposed wind-chimney could eventually be designed for use in commercial, retail, and multi-story buildings.
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Pretorius, Johannes Petrus. "Optimization and control of a large-scale solar chimney power plant /." Link to the online version, 2006. http://hdl.handle.net/10019.1/349.
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Spencer, Scott. "An experimental investigation of a solar chimney natural ventilation system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59298.pdf.
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Stockinger, Christopher Allen. "Numerical Analysis of Airflow and Output of Solar Chimney Power Plants." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71670.
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Computational fluid dynamics was used to simulate solar chimney power plants and investigate modeling techniques and expected energy output from the system. The solar chimney consists of three primary parts: a collector made of a transparent material such as glass, a tower made of concrete located at the center of the collector, and a turbine that is typically placed at the bottom of the tower. The collector absorbs solar radiation and heats the air below, whereby air flows inward towards the tower. As air exits at the top of the tower, more air is drawn below the collector repeating the process. The turbine converts pressure within the flow into power. The study investigated three validation cases to numerically model the system properly. Modeling the turbine as a pressure drop allows for the turbine power output to be calculated while not physically modeling the turbine. The numerical model was used to investigate air properties, such as velocity, temperature, and pressure. The results supported the claim that increasing the energy into the system increased both the velocities and temperatures. Also, increasing the turbine pressure drop decreases the velocities and increases the temperatures within the system. In addition to the numerical model, analytical models representing the vertical velocity without the turbine and the maximum power output from a specific chimney were used to investigate the effects on the flow when varying the geometry. Increasing the height of the tower increased the vertical velocity and power output, and increasing the diameter increased the power output. Dimensionless variables were used in a regression analysis to develop a predictive equation for power output. The predictive equation was tested with new simulations and was shown to be in very good agreement.Master of Science
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Pretorius, Johannes Petrus. "Optimization and control of a large-scale solar chimney power plant." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/349.
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Thesis (PhD (Mechanical and Mechatronic Engineering))-- University of Stellenbosch, 2007.ENGLISH ABSTRACT: The dissertation builds on previous research (Pretorius, 2004) and investigates the optimization and control of a large-scale solar chimney power plant. Performance results are based on a reference location near Sishen in South Africa and a so-called reference solar chimney power plant, with a 5000 m collector diameter and a 1000 m high, 210 m diameter chimney. The numerical simulation model is refined and used to perform a sensitivity analysis on the most prominent operating and technical plant specifications. Thermo-economically optimal plant configurations are established from simulation results and calculations according to an approximate plant cost model. The effects of ambient wind, temperature lapse rates and nocturnal temperature inversions on plant performance are examined. Various new technologies are investigated for the purpose of controlling plant output according to specific demand patterns. The incorporation of vegetation under the collector roof of the plant and the influence thereof on plant performance is also explored. Results indicate that, through the modification of the collector roof reflectance, collector roof emissivity, ground surface absorptivity or ground surface emissivity, major improvements on plant performance are possible. Introducing thermal insulation or double glazing of the collector roof also facilitates substantial enhancements on plant yield. Simulations predict a notable sensitivity to the ground surface absorptivity value, while variable atmospheric temperature lapse rates and windy ambient conditions may impair plant performance significantly. Furthermore, sand is found to be unsuitable as plant ground type and thermoeconomically optimal solar chimney plant dimensions are determined to be generally larger than plant dimensions employed in previous studies. Good dynamic control of solar chimney power output is established, suggesting that a solar chimney power plant can be implemented as a base or peak load electricity generating facility. Lastly, results predict that vegetation, when provided with sufficient water, will be able to survive under the collector roof but the inclusion of vegetation will however cause major reductions in plant performance.
AFRIKAANSE OPSOMMING: Die proefskrif bou op vorige navorsing (Pretorius, 2004) en ondersoek die optimering en beheer van 'n grootskaalse sonskoorsteen-kragstasie. Uitsetresultate word baseer op 'n verwysingsligging naby Sishen in Suid-Afrika en 'n sogenaamde verwysingskragstasie, met 'n kollektor deursnee van 5000 m en 'n 1000 m hoë, 210 m deursnee skoorsteen. Die numeriese rekenaarmodel is verbeter en gebruik vir die uitvoering van 'n sensitiwiteits-analise op die belangrikste bedryfs- en tegniese kragstasie spesifikasies. Termo-ekonomiese optimale aanlegkonfigurasies is bepaal volgens die uitsetresultate van die rekenaarmodel en benaderde aanleg-kosteberekeninge volgens 'n eenvoudige kostemodel. Die invloed van wind, atmosferiese temperatuur gradiënte en nagtelike temperatuur inversies op kragstasie uitset word beskou. Verskeie nuwe tegnologië word ondersoek met die doel om aanleg uitset te kan beheer volgens spesifieke elektrisiteit aanvraagspatrone. Die inkorporasie van plantegroei onder die kollektordak, en die invloed daarvan op kragstasie uitset, word ook beskou. Bevindings dui aan dat, deur die wysiging van die kollektordak refleksie, kollektordak emissiwiteit, grondoppervlak absorptiwiteit of grondoppervlak emissiwiteit, groot verbeterings op aanleg uitset moontlik is. Die implementering van termiese isolasie of 'n dubbelglaslaag vir die kollektordak veroorsaak ook 'n beduidende verheffing in kragstasie uitset. Simulasies voorspel 'n merkbare sensitiwiteit teenoor die grondoppervlak absorptiwiteitswaarde, terwyl veranderlike atmosferiese temperatuur daaltempos en winderige omgewingstoestande aanleg uitset beduidend mag belemmer. Verder is bevind dat sand ongeskik is as aanleg grond tipe en dat termo-ekonomiese optimale sonskoorsteen-kragstasie dimensies in die algemeen groter is as die aanvaarde aanlegdimensies van vorige studies. Goeie dinamiese beheer van sonskoorsteen-kragstasie uitset is bevestig, wat suggereer dat die sonskoorsteenkragstasie as 'n basis of pieklas elektrisiteitopwekkings-aanleg ingespan kan word. Ten laaste voorspel resultate dat plantegroei, mits dit voorsien word van genoegsame water, sal kan oorleef onder die kollektordak maar dat die inkorporasie van plantegroei die aanleg uitset beduidend sal benadeel.
Sponsored by the Centre for Renewable and Sustainable Energy Studies
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Fluri, Thomas Peter. "Turbine layout for and optimization of solar chimney power conversion units." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/4402.
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Thesis (PhD (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008.ENGLISH ABSTRACT: The power conversion unit of a large solar chimney power plant converts the fluid power, first into mechanical power, and then into electrical power. In this dissertation a tool is developed to determine the layout and the number of turbines of the solar chimney power conversion unit providing the lowest cost of electricity. First, the history of the solar chimney concept and the related fields of research are presented. Potential features and configurations of the power conversion unit are introduced, and it is shown how the solar chimney power conversion unit compares to those of other applications. An outline of the dissertation is given, and its potential impact is discussed. An analytical turbine model is developed. Several modelling approaches and the performance of single rotor and counter rotating turbine layouts are compared. Preliminary turbine designs are investigated, experimentally and numerically. The main aim of the experimental investigation is to verify the applicability of the loss model used in the analytical turbine model. The aim of the numerical investigation is to evaluate a commercial software package as a tool in context with solar chimney turbines. For each component of the power conversion unit an analytical performance model is introduced. Using these models, the single vertical axis, multiple vertical axis and multiple horizontal axis turbine configurations are compared from an efficiency and energy yield point of view, and the impact of the various losses on the overall performance is highlighted. A detailed cost model for the power conversion unit is also presented. To optimize for cost of electricity this cost model is then linked to the performance models, and the resulting optimization scheme is applied to several plant configurations. It is shown that for a large solar chimney power plant the power conversion unit providing minimal cost of electricity consists of multiple horizontal axis turbines using a single rotor layout including inlet guide vanes.
AFRIKAANSE OPSOMMING: Die drywingsomsettingseenheid van ’n groot sonskoorsteenaanleg sit die vloeidrywing om, eers in meganiese drywing en dan in elektriese drywing. In hierdie proefskrif word ’n gereedskapstuk ontwikkel om die uitleg en aantal turbines van die sonskoorsteen-drywingsomsettingseenheid te bepaal wat die laagste koste van elektrisiteit lewer. Eerstens word die geskiedenis van die sonskoorsteen en verwante navorsingsvelde behandel. Moontlike eienskappe en konfigurasies vir die drywingsomsettingseenheid word voorgestel, en daar word aangetoon hoe die sonskoorsteendrywingsomsettings- eenheid vergelyk met ander toepassings. ’n Raamwerk van die proefskrif word gegee, en die potensiële trefkrag daarvan word bespreek. ’n Analitiese turbine-model word ontwikkel. Verskeie nabootsingsbenaderings en die vertoning van ’n enkelrotor en teenroterende turbine-uitlegte word vergelyk. Voorlopige turbine-ontwerpe word ondersoek, eksperimenteel en numeries. Die hoofdoel van die eksperimentele ondersoek is om die toepaslikheid van die verliesmodel in die analitiese turbine-model te bevestig. Die doel van die numeriese ondersoek is om kommersiële sagteware op te weeg as ’n gereedskapstuk in die konteks van sonskoorsteenturbines. Vir elke onderdeel van die drywingsomsettingseenheid word ’n analitiese model voorgestel. Met gebruik van hierdie modelle word die enkele vertikale-as, die veelvoudige vertikale-as an die veelvoudige horisontale-as turbinekonfigurasies vergelyk vanuit ’n benuttingsgraad- en energie-opbrengsoogpunt,en die uitwerking van die verskillende verliese op die algehele gedrag word uitgewys. ’n Kostemodel in besonderhede word vir die drywingsomsettingseenheid aangebied. Om vir die koste van elektrisiteit te optimeer word hierdie kostemodel dan gekoppel aan die vertoningsmodelle, en die gevolglike optimeringskema word toegepas op verskeie aanlegkonfigurasies. Daar word aangetoon dat vir ’n groot sonskoorsteenaanleg die drywingsomsettingseenheid wat die minimumkoste van elektrisiteit gee, bestaan uit veelvoudige horisontale-as turbines met enkelrotoruitleg en inlaatleilemme.
Centre for Renewable and Sustainable Energy Studies
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Argiro, Dimoudi. "Investigation of the flow and heat transfer in a solar chimney." Thesis, University of Bath, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389950.
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Li, Y. "Thermal performance analysis of a PCM combined solar chimney system for natural ventilation and heating/cooling." Thesis, Coventry University, 2013. http://curve.coventry.ac.uk/open/items/0bca9412-8b49-4d3c-84e5-453e315d4c6b/1.
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Solar chimney is an important passive design strategy to maximize solar gain to enhance buoyancy effect for achieving adequate air flow rate and a desired level of thermal comfort inside a building. Therefore, solar chimney has the potential advantages over mechanical ventilation systems in terms of energy requirement, economic and environmental benefits. The main aim of this project is to study the technical feasibility of a solar chimney incorporating latent heat storage (LHS) system for domestic heating and cooling applications. The research work carried out and reported in this thesis includes: the development of a detailed theoretical model to calculate the phase change material (PCM) mass for solar chimney under specific climatic condition, the development of a CFD model to optimise the channel depth and the inlet and outlet sizes for the solar chimney geometry, experimental and numerical investigations of the thermal performance of the proposed system using a prototype set-up, a parametric study on the proposed system to identify significant parameters that affect the system performance was carried out by using the verified numerical model. The numerical and experimental study showed that the numerical model has the ability to calculate the PCM mass for the proposed system for the given weather conditions. The optimum PCM should be selected on the basis of its melting temperature, rather than its other properties such as latent heat. The experimental work on the thermal performance of the proposed system has been carried out. The results indicated that the LHS based solar chimney is technically viable. The outlet air temperature and the air flow rate varied within a small range during phase change transition period which are important for a solar air heating system. A numerical model was developed to reproduce the experimental conditions in terms of closed mode and open mode. The model results were in a close agreement with the experimental results particularly the simulated results for the discharging process. With the verified model, a comprehensive parametric analysis intended to optimise the thermal performance of proposed the system was performed. The results analysed are quantified in terms of charging/discharging time of the PCM, temperature difference between outlet air and inlet air of the solar chimney, and mass flow rate of the chimney, which are the most important quantities of the proposed system.
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Harris, Rhydar Lee. "A numerical analysis of the flow field surrounding a solar chimney power plant." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16337.
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Thesis (MScIng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: This study investigated the flow field above a proposed solar chimney power plant, without a cross wind, using a commercial numerical solver in the form of CFX 4-4 by AEA Technology plc. The governing equations solved are for an incompressible steady state solution. Variation in density due to buoyant effects is modelled with the Boussinesq approximation, and turbulence is approximated by the k-ε model with modifications due to buoyancy. The effect of different turbulence conditions at atmospheric inflows is also investigated. Modifications to the k-ε turbulence model in the context of atmospheric turbulence are investigated and applied to the standard k-ε model. These modifications include the addition of source terms in the turbulence kinetic energy and the turbulence dissipation rate equations to allow for the production/destruction of turbulence due to buoyancy. Other modifications include an additional source term in the turbulence dissipation rate equation accounting for atmospheric stability and the specification of model constants relevant to atmospheric flows. Initial results for the flow field using the Boussinesq approximation show reasonable correlation between the current study and the study by Thiart (2002) whereby the flow field exhibits characteristics of the axially symmetric turbulent jet. One of the primary and most noticeable differences between the current study and that of Thiart (2002) is the difference in height at which air is drawn into the collector. In order to account for variation in density with height, a modification on the Boussinesq approximation, the Deep Boussinesq model, Montavon (1998), is applied to a simplified 100 m by 100 m rectangular geometry. The results obtained are compared to a similar model using the Boussinesq approximation and it is seen that the average velocities reached in the deep Boussinesq model are significantly larger than those obtained in the Boussinesq approximation.
AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die vloeiveld bo 'n aangewese son-skoorsteen kragstasie, deur die gebruik van 'n kommersiële numeriese oplosser in die vorm van CFX 4-4; van AEA Technology plc. Die heersende vergelykings wat opgelos moet word, is vir 'n niesaampersbare, tyd-onafhanklike oplossing. Die wisseling in digtheid as gevolg van saamdrukbaarheids effekte, word gemodelleer met die Boussinesq benadering en turbulensie-skatting deur die k-ε model met aanpassings as gevolg van dryfkrag. Die effek van die verskillende turbulensie-toestande teen atmosferiese invloeing word ook ondersoek. Aanpassings op die k-ε turbulensie-model in die konteks van atmosferies turbulensie word ondersoek en toegepas op die standaard k-ε model. Hierdie veranderinge sluit die byvoeging van bron terme in die turbulente kinetiese energie en die turbulensieverspillings vergelykings om ruimte te laat vir die produksie/afbreking van turbulensie as gevolg van dryfkrag in. Ander aanpassings sluit in 'n bykomende bron term in die turbulensie-verspillings vergelyking wat rekenskap gee vir atmosferiese stabiliteit en die spesifikasie van model onveranderlikes met betrekking tot atmosferiese vloei. Aanvanklike resultate vir die vloeiveld met die gebruik van die Boussinesq benadering dui op geredelike ooreenstemming tussen de huidige studie en die studie van Thiart (2002), waar die vloeiveld eienskappe toon van 'n simmetriese turbulente spilpunt. Een van die mees primêre en duidelikste verskille tussen die huidige studie en diè van Thiart (2002) is die verskil in die hoogte waarteen die lug in die samesteller ingesuig word. Om rekenskep te kan gee vir die verskil in digtheid met betrekking tot hoogte is 'n aanpassing van die Boussinesq benadering, die Diep Bussinesq model, Montavon (1998), aangebring. Hierdie aanpassing word toegepas op ‘n vereenvoudigde 100 m by 100 m reghoek. Die resultate wat verkry word, word vergelyk met 'n soortgelyke model waar die algemene snelheid wat met die diep Boussinesq model bereik word merkbaar groter is as die in die Boussinesq benadering.
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Wheal, Richard. "Photocatalytic solar chimney for pre-heating air and the removal of VOCs." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415380.
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Talele, Suraj H. "A Performance Analysis of Solar Chimney Passive Ventilation System in the Unt Zero Energy Lab." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc499996/.
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The purpose of this investigation is to find out suitability of the solar chimney natural ventilation system in a Zero Energy Lab located at the University of North Texas campus, to figure out performance of the solar chimney. Reduction in the heating and ventilation and air conditioning energy consumption of the house has been also analyzed. The parameters which are considered for investigation are volumetric flow rate of outlet of chimney, the absorber wall temperature and glass wall temperatures. ANSYS FLUENT 14.0 has been employed for the 3-D modeling of the solar chimney. The dimensions of the solar chimney are 14’2” X 7’4” X 6’11”. The flow inside solar chimney is found to be laminar and the simulation results show that maximum outlet volumetric flow rate of about 0.12m3/s or 432 cfm is possible from chimney. The experimental velocity of chimney was found to be 0.21 m/s. Density Boussinesq approximation is considered for the modeling. Velocity and temperature sensors have been installed at inlet and outlet of the chimney in order to validate the modeling results. It is found that based on simulated volumetric flow rate that cooling load of 9.29 kwh can be saved and fan power of 7.85 Watts can be saved.
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Afriyie, John Kwasi. "Design, simulation and optimisation of a chimney-dependent direct-mode solar crop dryer (CDSCD)." Thesis, De Montfort University, 2007. http://hdl.handle.net/2086/4346.
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Frutos, Dordelly José Carlos. "Active Solar Chimney (ASC) : numerical and experimental study of energy storage and evaporative cooling." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSET008/document.
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Les conditions actuelles de réchauffement de la planète ont mené aux pays du monde à s'engager dans la durabilité et l’efficacité énergétique et la réduction des émissions de gaz à effet de serre. En tant que troisième consommateur d'énergie, le bâtiment représente un élément clé envers l'efficacité énergétique et de la stabilisation de la température globale. Plusieurs solutions existent pour la réalisation de ces objectifs, et les travaux présentés tout au long de cette thèse concernent un composant solaire particulier à la construction externe du bâtiment, appelé cheminée solaire. Cette thèse de doctorat porte sur l'analyse expérimentale et numérique des dispositifs de stockage d'énergie, sous forme de matériaux à changement de phase (PCM), afin d'optimiser les performances de cette technologie solaire. Le but de cette étude est de caractériser l’impact des panneaux Rubitherm RT44 PCM sur une cheminée solaire en laboratoire et in situ afin de permettre une comparaison avec la version classique. De plus, un modèle numérique a été développé et testé dans le but d'obtenir un outil numérique capable de représenter le comportement d'une cheminée solaire. Enfin, une optimisation à deux objectifs du modèle numérique de cheminée solaire intégrée PCM a été réalisée afin de déterminer certains des paramètres optimaux de ce type de technologie afin d’obtenir le flux d’air sortant le plus élevé possible, tout en maintenant une température suffisamment élevée dans la cheminée atteindre la gamme de fusion des PCMThe current global warming conditions have led nations across the world to commit into energetic sustainability and greenhouse gas emission reduction. Being the third greatest energetic consumer, the building represents a major key towards energy efficiency and global temperature stabilization. Several solutions exist for the accomplishment of these goals, and the works presented throughout this dissertation concerns a particular external building solar-driven component known as solar chimney. This PhD thesis focuses on the experimental and numerical analysis of energy storage devices, in the form of Phase Changing Materials (PCMs), for the optimisation of the performance of this solar technology. The aim of this study is to characterize the impact of Rubitherm RT44 PCM panels on a solar chimney under laboratory and in-situ conditions to carry out a comparison against the classic version. Additionally, a numerical model was developed and tested in the interest of obtaining a numerical tool capable of representing the behaviour of a solar chimney. Finally a bi-objective optimization of the PCM integrated solar chimney numerical model was carried out in order to determine some of the optimal parameters of this type of technology to obtain the highest exiting air flow, all while maintaining a high enough temperature across the chimney to reach the fusion range of the PCMs
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JACONELLI, LIVIO, and PALM KIM JACONELLI. "A THERMAL NETWORK MODEL FOR AN EVAPORATIVE COOLING SYSTEM COMBINED WITH A SOLAR CHIMNEY." Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192670.
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Syftet med denna studie är att, genom termiskt nätverksmodellering för kombinerad värme och massöverföring, undersöka möjligheten att integrera en solskorsten med en evaporationskyl. Avsikten är att potentiellt öka luftflödet runt kylen samt dess kylförmåga. Jämviktstillstånd samt transienta förlopp simuleras med hjälp av mjukvaruprogrammet MATLAB. Utfallet av studien indikerar att föreslagna tillämpningsområdet för solskorstenen ökar kylpotentialen för evaporationskylen. Solskorstenen kan generera ett tillräckligt luftflöde på mer än 0.5 m/s. Med en omgivningstemperatur på 30 C°, luftfuktighet på 40 % och ett luftflöde på 0.5 m/s kan evaporationskylen bibehålla 25 % lägre förvaringstemperatur gentemot omgivningstemperaturen.The purpose of this study is to, through thermal network modelling and coupled heat and mass transfer analysis, investigate the cooling process of an evaporation fridge combined with a solar chimney. The solar chimney is connected to the evaporation fridge in an attempt to increase the airflow, around the evaporation fridge, and the cooling capacity. Steady state and transient regimes are simulated in the software MATLAB. The findings indicate that utilizing a solar chimney for the stated purposes will increase the cooling potential of the evaporation fridge. The solar chimney is able to produce a satisfactory air flow velocity of more than 0.5 m/s. With an ambient temperature of 30 C°, relative humidity at 40 % and an air flow rate of 0.5 m/s the evaporation fridge maintains a 25 % lower storage temperature compared to the ambient temperature.
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Beyers, Johannes Henricus Meiring. "A finite volume method for the analysis of the thermo-flow field of a solar chimney collector." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51568.
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Thesis (MEng)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: This study investigates the implementation of the finite volume numerical method applicable to non-orthogonal control volumes and the application of the method to calculate the thermo-flow field within the collector area of a solar chimney power generating plant. The discretisation of the governing equations for the transient, Newtonian, incompressible and turbulent fluid flow, including heat transfer, is presented for a non-orthogonal coordinate frame. The standard k - E turbulence model, modified to include rough surfaces, is included and evaluated in the method. An implicit solution procedure (SIP-semi implicit procedure) as an alternative to a direct solution procedure for the calculation of the flow field on nonstaggered grids is investigated, presented and evaluated in this study. The Rhie and Chow interpolation practice was employed with the pressurecorrection equation to eliminate the presence of pressure oscillations on nonstaggered grids. The computer code for the solution of the three-dimensional thermo-flow fields is developed in FORTRAN 77. The code is evaluated against simple test cases for which analytical and experimental results exist. It is also applied to the analysis of the thermo-flow field of the air flow through a radial solar collector. KEYWORDS: NUMERICAL METHOD, FINITE VOLUME, NON-ORTHOGONAL, k+-e TURBULENCE MODEL, SIP
AFRIKAANSE OPSOMMING: Die studie ondersoek die implementering van 'n eindige volume numeriese metode van toepassing op nie-ortogonale kontrole volumes asook die toepassing van die metode om die termo-vloei veld binne die kollekteerder area van 'n sonskoorsteen krag aanleg te bereken. Die diskretisering van die behoudsvergelykings vir die tyd-afhanlike, Newtonse, onsamedrukbare en turbulente vloei, insluitende hitteoordrag, word beskryf vir 'n nie-ortogonale koordinaatstelsel. Die standaard k - E turbulensiemodel, aangepas om growwe oppervlakrandvoorwaardes te hanteer, is ingesluit en geevalueer in die studie. 'n Implisiete oplossings metode (SIP-semi implisiete prosedure) as alternatief vir 'n direkte oplossingsmetode is ondersoek en geimplimenteer vir die berekening van die vloeiveld met nie-verspringde roosters. 'n Rhie en Chow interpolasie metode is gebruik tesame met die drukkorreksie-vergelyking ten einde ossilasies in die drukveld in die nie-verspringde roosters te vermy. Die rekenaarkode vir die oplossing van die drie dimensionele termo-vloeiveld is ontwikkel in FORTRAN 77. Die kode is geevalueer teen eenvoudige toetsprobleme waarvoor analitiese en eksperimentele resultate bestaan. Die kode IS ook gebruik om die termo-vloeiveld binne 'n radiale son kollekteerder te analiseer. SLEUTELWOORDE: NUMERIESE METODE, EINDIGE VOLUME, NIE-ORTOGONAAL, k - E TURBULENSIE MODEL, SIP
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Oliveira, Hugo Sergio Medeiros de. "An?lise da indu??o de fluxo de ar por convec??o livre em chamin? solar." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15695.
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Previous issue date: 2012-11-30Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
Experiments were performed to study the effect of surface properties of a vertical channel heated by a source of thermal radiation to induce air flow through convection. Two channels (solar chimney prototype) were built with glass plates, forming a structure of truncated pyramidal geometry. We considered two surface finishes: transparent and opaque. Each stack was mounted on a base of thermal energy absorber with a central opening for passage of air, and subjected to heating by a radiant source comprises a bank of incandescent bulbs and were performed field tests. Thermocouples were fixed on the bases and on the walls of chimneys and then connected to a data acquisition system in computer. The air flow within the chimney, the speed and temperature were measured using a hot wire anemometer. Five experiments were performed for each stack in which convective flows were recorded with values ranging from 17 m? / h and 22 m? / h and air flow velocities ranging from 0.38 m / s and 0.56 m / s for the laboratory tests and air velocities between 0.6 m/s and 1.1m/s and convective airflows between 650 m?/h and 1150 m?/h for the field tests. The test data were compared to those obtained by semi-empirical equations, which are valid for air flow induced into channels and simulated data from 1st Thermodynamics equation. It was found that the chimney with transparent walls induced more intense convective flows than the chimney with matte finish. Based on the results obtained can be proposed for the implementation of prototype to exhaust fumes, mists, gases, vapors, mists and dusts in industrial environments, to help promote ventilation and air renewal in built environments and for drying materials, fruits and seeds
Estudou-se o efeito do acabamento da superf?cie de um canal vertical aquecido por uma fonte de radia??o t?rmica na indu??o de fluxo de ar por convec??o livre. Dois canais (prot?tipos de chamin? solar) foram constru?dos com placas de vidro, compondo uma estrutura de geometria tronco-piramidal. Consideraram-se dois acabamentos de superf?cie: transparente e opaco. Cada chamin? foi montada sobre uma base absorvedora de energia t?rmica, com uma abertura central para passagem de ar, e submetidas a aquecimento por meio de uma fonte radiante composta por um banco de l?mpadas incandescentes e foram feitos ensaios em campo. Termopares foram fixados nas bases absorvedoras e nas paredes das chamin?s e, em seguida, conectados a um sistema de aquisi??o de dados por computador. O fluxo de ar no interior da chamin?, sua velocidade e temperatura foram medidos utilizando-se um anem?metro de fio quente. Realizaram-se cinco ensaios para cada chamin?, nos quais foram registrados fluxos convectivos com valores variando entre 17 m?/h e 22 m?/h e velocidades de escoamento de ar variando entre 0,38 m/s e 0,56 m/s para os ensaios em laborat?rio e velocidades entre 0,6 m/s e 1,1 m/s e fluxos de ar variando entre 650 m?/h e 1150 m?/h para os ensaios em campo. Os dados dos ensaios foram comparados ?queles obtidos por meio de equa??es semi-emp?ricas, v?lidas para escoamento de ar induzido em canais e com dados obtidos atrav?s da 1? lei da Termodin?mica. Constatou-se que a chamin? com paredes transparentes induziu fluxos convectivos mais intensos que a chamin? com acabamento opaco. Com base nos resultados obtidos pode-se propor a aplica??o do prot?tipo para exaust?o de fumos, n?voas, gases, vapores, poeiras e neblinas em ambientes industriais, para auxiliar na promo??o de ventila??o e renova??o de ar em ambientes constru?dos e para secagem de materiais, frutas e sementes
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Čišecký, Ladislav. "Budovy pro vzdělávání - energie a vnitřní prostředí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265546.
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Diploma thesis deals with evaluation of indoor environment of a school complex in atypical Himalayan alpine environment which is totally dependent on energy originating from renewable sources. Structural design of buildings allows maximum utilization of solar energy which is the only one actually available source of energy in this area. The buildings are de-scribed in detail, as well as measurement conducted in buildings during the last year. The out-comes of measurements are compared with desired values. The thesis is also focused on math-ematical simulations by using BSim software. The output of a building energy simulations is an energy use prediction and design of appropriate measures to improve the current situation.
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Herbst, Herbst Markus Günter [Verfasser]. "Solar Chimney Power Plant - A Holistic Approach to the Improvement of the Flow within the Transition Section / Herbst, Markus Günter Herbst." Wuppertal : Universitätsbibliothek Wuppertal, 2018. http://d-nb.info/1173805060/34.
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Hartinger, Stella M., Claudio F. Lanata, Ana I. Gil, Jan Hattendorf, Hector Verastegui, and Daniel Mäusezahl. "Combining interventions: improved chimney stoves, kitchen sinks and solar disinfection of drinking water and kitchen clothes to improve home hygiene in rural Peru." Institut Veolia Environnement, 2014. http://hdl.handle.net/10757/314662.
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Home based interventions are advocated in rural areas against a variety of diseases. The combination of different interventions might have synergistic effects in terms of health improvement and cost effectiveness. However, it is crucial to ensure cultural acceptance. The aim of the study was to develop an effective and culturally accepted home-based intervention package to reduce diarrhoea and lower respiratory illnesses in children. In two rural Peruvian communities we evaluated the performance and acceptance of cooking devices, household water treatments (HWT) and home–hygiene interventions, with qualitative and quantitative methods. New ventilated stove designs reduced wood consumption by 16%. The majority of participants selected solar water disinfection as HWT in a blind tasting. In-depth interviews on hygiene improvement further revealed a high demand for kitchen sinks. After one year of installation the improved chimney stoves and kitchen sinks were all in use. The intervention package was successfully adapted to local customs, kitchen-, home–and hygiene management. High user satisfaction was primarily driven by convenience gains due to the technical improvements and only secondarily by perceived health benefits.Revisión por pares.
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Van, Dyk Cobus. "A methodology for radical innovation : illustrated by application to a radical civil engineering structure." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/2045.
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Cavalcanti, Fernando Antonio de Melo Sá. "Chaminé solar como alternativa para incrementar a ventilação natural em espaços internos." Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/4650.
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Previous issue date: 2010-08-02Financiadora de Estudos e Projetos
This work aims to investigate the influence of solar chimneys in the natural ventilation in buildings located in Brazil. Considering that Brazil is a tropical country and has a great potential for the harnessing of solar radiation, it is intended to verify the hypothesis that the use of this device may increase air movement in indoor spaces contributing to promote thermal comfort for users of these environments. The methodology used to verify this hypothesis was based on comparing the performance of two construction systems: a conventional chimney and a solar chimney. The two models have the same height and dimensions for the air inlet and outlet. This comparison was performed by computer simulations using EnergyPlus software, for eight Brazilian cities located in each one of the bioclimatic zones of Brazil, during winter and summer. The investigated device showed satisfactory performance, increasing natural ventilation during the day in all cities simulated, even in winter, when natural ventilation may not be desired in some climates. The data were presented to facilitate the understanding of professionals in the Construction Industry in general, contributing to establish a theoretical framework on the subject, and projective guidelines for more efficient buildings from the standpoint of energy. It is also intended to contribute to the potential of this device is investigated in several Brazilian regions, always trying to adapt the buildings to the climate of where it will be built.
Este trabalho tem como finalidade investigar a influência que o uso de chaminés solares possuem na ventilação natural em edifícios localizados no Brasil. Tendo em vista que o Brasil é um pais tropical e possui um grande potencial para aproveitamento da Radiação Solar, pretende-se verificar a hipótese de que a utilização deste dispositivo pode incrementar a ação dos ventos em espaços internos de modo a contribuir na promoção do conforto para os usuários destes ambientes. A metodologia utilizada para verificar esta hipótese foi baseada na comparação entre o desempenho de dois sistemas construtivos: um dotado de chaminé convencional e outro com chaminé solar, sendo os dois modelos com a mesma altura e dimensões para aberturas de entrada e saída do ar. Esta comparação foi realizada a partir de simulações computacionais utilizando o software EnergyPlus, para 8 cidades brasileiras, representativas de cada uma das zonas bioclimáticas do pais, nos períodos de inverno e verão. O dispositivo investigado apresentou desempenho satisfatório, aumentando a ventilação natural no período diurno em todas as cidades simuladas, inclusive no período de inverno, quando a ventilação natural pode não ser desejável em alguns climas. Os dados foram apresentados de forma a facilitar o entendimento dos profissionais da Construção Civil em geral, visando contribuir para estabelecer um referencial teórico sobre o assunto, alem de diretrizes projetuais para edifícios mais eficientes do ponto de vista energético. Pretende-se também contribuir para que o potencial deste dispositivo seja investigado nas mais diversas regiões brasileiras, buscando adaptar sempre as edificações ao clima do sitio onde serão construídas.
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Mitogo, Eseng Jesus Nvé. "Qualification expérimentale des performances d'un dispositif de bardage avec lame d'air tampon et parement en bois." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14495/document.
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Aujourd’hui à de nombreuses études sur la thermique du bâtiment pour réduire la consommation d’énergie tout en préservant le confort des usagers sont proposées. Le travail présenté ici met en avant les performances d’une technique d’isolation active par un dispositif de bardage extérieur de ce fait soumis au rayonnement solaire incident. L’étude expérimentale mise en oeuvre a permis de caractériser les échanges thermiques à l’intérieur de la lame d’air verticale (circulante ou non circulante), qui sont la clef de ce type de dispositif, en fonction des différents paramètres retenus comme pertinents. Le terme moteur est bien évidemment l’éclairement solaire. La distance parement extérieur mur support, i.e. l’épaisseur de la lame d’air, conditionne un rapport d’aspect et influe donc sur la vitesse de l’air circulant ou sur le volume tampon en situation non circulante et donc sur les échanges thermiques. Enfin les caractéristiques thermiques du parement extérieur, ici une lame de pin maritime ou un bois aggloméré, impactent assez fortement sur l’évolution temporelle des différentes. Une modélisation globale du comportement de la cheminée solaire que constitue le bardageet quelques simulations numériques ont permis de conforter ces différents résultats expérimentaux. On retiendra qu’en été, la solution optimale est un dispositif de bardage avec peu d’inertie thermique et un écoulement d’air rapide alors qu’en hiver, un dispositif avec inertie et sans écoulement contribue à assurer un bon volant thermiqueToday many studies on thermal building to reduce energy consumption while maintaining user comfort are proposed. The work presented here highlights the performance of an active isolation technique by means of exterior cladding thus subjected to solar radiation.The experimental study has been used to characterize the heat transfers inside the vertical cavity (air circulating or not), which are the key to this type of device, depending on various parameter staken as relevant. The driving factor is of course the solar irradiance. The thickness of the air gap induces an aspect ratio and thus affects the speed of the air flowing or the buffer volume and therefore the heat exchanges. Finally, the thermal characteristics of the cladding here maritime pine or chipboard, impact quite strongly on the temporal evolution of the different temperatures.The cladding and the vertical cavity act as a solar chimney, a global modeling of its behavior and some numerical simulations have strengthened the experimental results. We note that in summer, the optimal solution is a device of cladding with little thermal mass an drapid air flow while in winter, a device with large thermal mass and without flow helps to ensure a good thermal flywheel
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León, Vázquez Juan Carlos. "La chimenea solar : parámetros de diseño de un sistema pasivo generador de movimiento de aire." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/462143.
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The solar chimney is a climatic conditioning passive system. This can generate air movements in a room by means of solar radiation. These air movements can amplify the comfort zone increasing human habitability conditions at high air temperature and humidity rates, main characteristics of warm tropical humid climate.
Although this device has extensive diffusion in literature related to energy efficiency and environment, its real application in architecture is limited. This research aims to identifying the design parameters affecting the performance of the solar chimney, by studying the device morphology as well as the position of the openings involved in the air flow path.
The evaluation process begins with the implementation of a basic model within the DesignBuilder software, establishing some calculation points, mainly the point called HAB that emulates the user's position within the room. Subsequently, the construction of an experimental model, which collects the results of the simulation stage, evaluates the behavior of the solar chimney in the generation of air movements to the center of the room and in the entrance opening of the chimney for a complete annual cycle. It is possible to evaluate its performance in different climatic scenarios.
Finally, comparison of the velocity records for the points of calculation of the experimental model with those calculated by Design Builder to determine the degree of approximation of the computer tool.
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Khaldi, Souheyla. "Etude numérique du comportement thermique d’un séchoir solaire utilisant un lit thermique pour le stockage d’énergie." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCA008/document.
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Cette thèse présente une étude numérique d’un séchoir solaire indirect à convection naturelle destiné à sécher les produits agricoles (les figues). La première partie analyse un séchoir solaire contenant une chambre de séchage couplée à un absorbeur inversé et une cheminée solaire. Les simulations ont été faites afin de déterminer les champs dynamique et thermique sous l’influence de la variation de la configuration de la cheminée solaire et la taille de l’ouverture d’admission. Les équations de conservations basées sur le modèle de turbulence k-ε standard sont résolues par la méthode des volumes finis à l’aide du code commercial ANSYS-Fluent. La deuxième partie analyse l’effet d’ajouter un stockage thermique sous forme d’un lit en gravier dans la chambre de séchage. Le lit est modélisé comme un milieu poreux. En plus, cette étude propose l’utilisation d’une deuxième entrée d'air dans la chambre de séchage afin d’assurer une distribution thermique plus homogène au niveau des claies et de garantir un séchage plus uniformeThis thesis presents a numerical study of an indirect natural convection solar dryer for drying agricultural products (Figs). The first part analyzes a solar dryer containing a drying chamber coupled to a reversed absorber and a solar chimney. Simulations were made to determine the dynamic and thermal fields under the influence of the variation of the solar chimney configuration and the size of the inlet opening. The governing equations based on the standard k-ε turbulence model are solved by the finite volume method using the ANSYS-Fluent commercial code. The second part analyzes the effect of adding a thermal storage in the form of a gravel bed in the drying chamber. The bed is modeled as a porous medium. Furthermore, this study proposes the use of a second air inlet in the drying chamber in order to ensure a more homogeneous thermal distribution at the level of the racks and to guarantee a more uniform drying
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Ahmadi, Moghadam Parham. "Steel Sheet Applications and Integrated Heat Management." Thesis, Högskolan Dalarna, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:du-21446.
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Increasing energy use has caused many environmental problems including global warming. Energy use is growing rapidly in developing countries and surprisingly a remarkable portion of it is associated with consumed energy to keep the temperature comfortable inside the buildings. Therefore, identifying renewable technologies for cooling and heating is essential. This study introduced applications of steel sheets integrated into the buildings to save energy based on existing technologies. In addition, the proposed application was found to have a considerable chance of market success. Also, satisfying energy needs for space heating and cooling in a single room by using one of the selected applications in different Köppen climate classes was investigated to estimate which climates have a proper potential for benefiting from the application. This study included three independent parts and the results related to each part have been used in the next part. The first part recognizes six different technologies through literature review including Cool Roof, Solar Chimney, Steel Cladding of Building, Night Radiative Cooling, Elastomer Metal Absorber, and Solar Distillation. The second part evaluated the application of different technologies by gathering the experts’ ideas via performing a Delphi method. The results showed that the Solar Chimney has a proper chance for the market. The third part simulated both a solar chimney and a solar chimney with evaporation which were connected to a single well insulated room with a considerable thermal mass. The combination was simulated as a system to estimate the possibility of satisfying cooling needs and heating needs in different climate classes. A Trombe-wall was selected as a sample design for the Solar Chimney and was simulated in different climates. The results implied that the solar chimney had the capability of reducing the cooling needs more than 25% in all of the studied locations and 100% in some locations with dry or temperate climate such as Mashhad, Madrid, and Istanbul. It was also observed that the heating needs were satisfied more than 50% in all of the studied locations, even for the continental climate such as Stockholm and 100% in most locations with a dry climate. Therefore, the Solar Chimney reduces energy use, saves environment resources, and it is a cost effective application. Furthermore, it saves the equipment costs in many locations. All the results mentioned above make the solar chimney a very practical and attractive tool for a wide range of climates.
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Šimonová, Lucie. "Distribuční soustava Kypru - realizovatelnost obnovitelných zdrojů a přenos energie." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219218.
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Until a few decades ago few people could imagine that the photovoltaic, solar thermal and other power based on renewable resources, will become a reality. Today people from all over the world on the contrary try at full blast derive benefit from of all possible available source. Using sunlight as a source of energy is first enforced only for small devices such as calculators for charging the battery, but now we are able to produced energy from the sun to supply people around the world. Of course it is not possible supply consumer sector plus firm only from performances renewable power supply. Therefore endeavour is derive benefit from classical energy production at the same time with others power supply. The basic components of photovoltaic and solar thermal power are panels. The panels are made of different materials in different shapes and sizes. During production, the resulting effect looks in addition to costs associated with production. For photovoltaic and solar thermal power plant requires sufficient sunlight. The sunshine has biggest intensity on south of ours planets. Therefore endeavour is build lump these power station just in stand with bigger intensity sunshine. One of them is just Cyprus, too.
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Chen, Chun-Hung, and 陳俊宏. "Energy Conversion Improvement Study of A Solar Chimney." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/08568351758237130272.
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碩士國立成功大學
航空太空工程學系碩博士班
96
The purpose of this study is to investigate experimentally the internal flow temperature and flow pattern distribution inside a solar chimney. Factors that affect the chimney outlet velocity and hence improvements for better mass flow are discussed to increase the power generation efficiency of the solar chimney. Different geometries of the chimney tower and various means of solar thermal collection are tested to determine the influence on the flow rate. The study of flow entrance height , ranging from 1, 3, 5, and 10cm, suggests a clearance of 5 cm can be the best for available apparatus. The increase of the heat transfer area by installing fins upon the heating plate for different mass flow rate and internal temperature shows an increase in internal temperature but no significant effect in outlet velocity. A further study was to block the chimney heat loss with insulation. However, the experiment shows that the insulation bids no benefits in either temperature difference or the outlet velocity. For chimney tower geometry effect, the original acrylic chimney tower was replaced by divergent metal ones, bearing divergent angle of 2°, 6°, and 8°. The experimental results suggest significant increase in internal flow velocity in each case, while the best performance lays in the 6° case.
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Huang, Tsung-Jie, and 黃琮傑. "The investigation and analysis of solar collector combined with solar chimney by using CFD." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/32645885139897447519.
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碩士國立清華大學
工程與系統科學系
103
solar air collector concept is used to induce natural cooling and reduce heat leak into the indoor simultaneously. In this study, the waste heat can be potentially employed for electricity generation by the organic Rankie cycle (ORC) system. The purpose of this study is to perform the flow and heat of solar ventilation by commercial CFD code. To Make numerical result accurate, the Solar Ray Tracing was used instead of set isothermal or constant heat flux on the wall. This study including both experiment and numerical simulation studies how to efficiently gather this solar thermal energy. The local heat transfer correlation was investigated to predict surrounding wind speed upon device cover. Three glass sort and several channel aspect ratio was compared to know the best configuration. It is also discuss the stagnant layer thickness, emissivity on the illustrated surface, mass flow rate and device height. Consequently, the relationship between mass flow rate and device height is found to know the suitable mass flow rate at different device height.
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Yu, Mong-Yu, and 游孟諭. "Numerical and Experimental Study of Roof-Top Insulation and Solar Chimney." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/68776697632053082886.
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碩士崑山科技大學
機械工程研究所
100
This paper presents a study of roof insulation materials for energy efficiency. Numerical analysis was made with COMSOL multi-physics software to investigate transient temperature distribution of a model room. Comparisons were made between different roof insulation materials and thickness the insulation layers. The impact of room insulation on energy saving is obvious through the simulation. The temperature difference could be as large as 10℃, under three hours of sun light. However, the differences between commercially available roof insulation materials are not that significant, mostly within 1℃. Therefore it is advisable that the cheaper Styrofoam may be a good choice. For thickness concern, the numerical results demonstrated that minimum of 2cm is necessary and after 6cm, the effect will not be that obvious. Therefore a thickness of 2cm-6cm could be considered for insulation material. The second part of the thesis is about the design of a solar chimney which can serve ventilation purpose for buildings. To thoroughly understand the mechanism of the solar chimney, steady state 2-demensional numerical analysis was conducted to investigate temperature distribution, velocity profile and mass air flow due to the sunshine. Design parameters such as Total height of the chimney and the angle oriented; the thickness of the air passage; the material and the thickness of the heating plate were investigated. Moreover, a lab-scale solar chimney was built and tested to verify the numerical predictions with reasonable results.
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Beneke, Louis. "Development and performance investigation of a novel solar chimney power generation system." 2015. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001691.
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D. Tech. Mechanical Engineering, Mechatronics and Industrial DesignSouth Africa has limited reserve electricity resources and many parts of the country have limited access to electricity. Electricity production capacity is at maximum and almost each Giga watt is accounted for. Predictions suggest South Africa would have a serious electricity allocation problem in the very near future and current rolling blackout in many of our cities can attest to the looming problem. The energy crisis in South Africa has highlighted the need to increase electricity generation capacity and to search for alternative energy sources. Solar chimney plants could form part of the solution in the near future in South Africa to create additional power. This study aimed to develop a wind generation system in areas where wind is absent. A solar chimney power plant is expected to provide remote areas in South Africa with electric power, or to complement the current electricity grid. Solar energy and the psychometric state of the air are important to encourage the full development of a solar chimney power plant for the thermal and electrical production of energy for various uses. Research within the South African context and particularly on increasing the effectiveness of the solar chimney power plant technology is lacking; as such this study proposes the development of a solar chimney plant and associated technology to ensure the effectiveness of this plant.
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Sau, Arunabha. "Low-energy Passive Solar Residence in Austin, Texas." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8193.
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From the various studies, it can be concluded that the excessive summer heating and the humidity are one of the major problems of the hot, humid climatic region. The literature review for this study shows that natural ventilation alone cannot meet year long optimum indoor comfort in buildings. This research, through a design exercise, intends to verify whether a naturally ventilated house, in hot humid region of Austin, TX, can enhance its passive cooling potential through double‐walled wind catcher and solar chimney.
In this research, a passive solar residence has been designed. Two designs have been explored on the chosen site: a basecase design without the wind catcher and solar chimney and another design with wind catcher and solar chimney. In the designcase, the placement of the wind catcher and the solar chimney has been designed so that a thermal siphon of airflow inside the building can be created. The design might show that there will be a natural airflow during the time of the year when natural wind does not flow. Moreover, the double walled wind catcher will resist the cool winter wind due to its shape and orientation. In the design, the placement of the wind catcher and the solar chimney has been done so that a thermal siphon inside the building can be created. Therefore, inside the home, there will be a natural airflow during the time of the year when natural wind does not flow. The double walled wind catcher has been designed and placed according to the orientation of the building in order to achieve the optimum wind flow throughout the year. The solar chimney has been placed in a certain part of the building where it can get maximum solar exposure.
By comparing two cases, it can be clearly said that there will some kind of changed indoor comfort level. Since the potential of the design has been judged through perception, a computational fluid dynamics simulation analysis for a year is to be done.
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Wang, Jhin-Yong, and 王智勇. "A Study on Applying Solar Chimney and Trombe Wall to a Building of Natural Ventilation." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/40376640371996017110.
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碩士國立臺灣科技大學
機械工程系
97
This research uses Computational Fluid Dynamics (CFD) program, Flovent, to analyze buoyancy ventilation effect in a three-story building with a solar chimney and a Trombe wall. In this study ambient parameters and building physical parameters are varied to analyze the change of natural ventilation efficiency. The analyzed parameters include solar time (at the same solar day), Trombe wall materials (Aluminum, Brick and Fiber glass) and transmittance of glass in the solar chimney. CFD program uses the finite volume method and standard two-equation k-E turbulence model to calculate air flow and temperature distribution in the building. According to the simulation results of different Trombe wall materials, when the material of the wall is Fiber glass, walls can absorb solar radiation in them and provide heat energy to indoor air. Main buoyancy driven force of indoor ventilation is from heating walls. Buoyancy effect of solar chimney is weaker than heating walls. Therefore solar chimney with Trombe wall does not have significant effect on indoor ventilation. For the glass transmittance, this series of simulation has similar results. The construction configuration is not symmetrical. The northern room has a protrusive square part to the west, and the southern room is facing the sun directly at noon. The northern room is asymmetric to the sun at different solar time. At the same solar altitude angle the northern room has different indoor environment performance. When the wall is made of insulation material, the main buoyancy driven force of indoor ventilation is due to solar chimney. Indoor exchange flow rate increases when solar chimney with Trombe wall of higher specific heat and higher density. For higher transmittance of glass, indoor air receives more solar radiation, and that causes higher indoor exchange flow rate. The high absorption of glass can store heat inside itself to provide heat energy for indoor air.Indoor temperature does not vary much for different solar chimney glass properties when the wall is made of insulation material. Only the top of solar chimney has different temperature distribution for different values of transmittance and absorption. When the solar azimuth angle is different and the solar altitude angle is the same to solar chimney, the indoor exchange flow rate does not change a lot. When the solar time is at twelve o'clock, solar chimney glass receives the most solar radiation and indoor environment has the highest ventilation rate. The neutral level in solar chimney does not change much for the same wall material. When the wall is made of Fiber glass, buoyancy effect of heating wall is higher than that of solar chimney. Different Trombe wall and glass transmittance does not affect the indoor environment much,Only different solar radiation angle changes the properties of indoor environment. When the wall is made of insulation material, the buoyancy driven force is mainly due to solar chimney. Different building physical parameters and ambient parameter change indoor environment Performance.
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Yu-TingWu and 吳玉婷. "Ventilation Efficiency Analysis of Passive Solar Chimney－A Case Study of the Exhibition Room in the Magic School of Green Technology." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66195484912264120945.
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碩士國立成功大學
建築學系碩博士班
98
Due to energy crisis and the increasing energy-saving consciousness, natural ventilation techniques for buildings consequently caught a lot of attention. However, natural ventilation will be affected by outdoor climatic conditions, such as smaller pressure differences due to heat or wind and can cause design instability. Solar chimney is a design to strengthen natural ventilation, thermal pressure differential and ventilation rate manipulation. It can improve the weakness of instability and difficulties of natural ventilation. So this study explores the issue of ventilation efficiency of solar chimney. The research investigates the performance of the solar chimney of the exhibition room of the Magic School of Green Technology as a case study by the method of computational fluid dynamics, supplemented by scale model experiments to verify the accuracy of CFD simulations. Through the structural variation of the solar chimney and the outdoor climatic conditions on the ventilation, the following main results are obtained. In terms of ventilation efficiency and human thermal comfort in the exhibition room under different seasonal conditions, the ventilation rate is much larger than the regulatory requirement irrespective of spring/autumn or summer season, and is consistent with the basic ventilation health needs. For human thermal comfort, the applicability of solar chimney in spring/autumn is better than in summer. While the external temperature is 26℃ in spring/autumn, the interior temperature is between 26℃~27.2℃, and the interior wind speed is between 0.1m/s ~ 0.2m/s. The equivalent temperature reduction is between 0.5℃~1.1℃; namely the indoor temperature meets the 90% acceptability limits of 23.5℃~28.5℃. But when the external temperature is 30℃ in summer, the interior temperature only meets 80% of the acceptability limits. External wind is helpful for increasing the ventilation efficiency of the passive solar chimney. In comparison with the situation of no outdoor wind under the same conditions, the ventilation rate of the exhibition room increases 13.4%~22.2%, and the ACH increases 2.9h-1~3.8h-1. The ventilation rate increases most in the spring/autumn afternoon, and least in the summer morning.
49
Chien, Chun-han, and 簡君翰. "Energy Efficiency Analysis of Passive Solar Chimney - A Case Study on the International Conference Hall of the Magic School of Green Technology." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/26007073936390845676.
Full textAbstract:
碩士國立成功大學
建築學系碩博士班
97
Limited to the ventilation route and using function, most of the large-scale indoor space will choose to utilize the air-conditioning system to solve the condition of ventilation and air exchanging. If it can be considered seriously at the first planning, there might be great benefits for environmental comfortableness and energy conservation. That is why this study focuses on this topic. This research is a case study on the international conference hall of the Magic School of Green Technology. Using Computational Fluid Dynamics (CFD) to predict the efficiency of natural ventilation of the passive solar chimney used in large-scale indoor space, at the same time, and to enhance the simulation accuracy by confirmed the theoretical formula. The results shows that people will feel comfortable when there is no outdoor wind blows into the indoor space, and the indoor wind speed is between the range of 0.15 m/s ~ 0.75 m/s. Ventilation during the day and night are 8.23 ACH and 6.72 ACH. After increasing the wind-driven ventilation, the air change of the international conference hall is 15.2h-¹ per hour. This output is also corresponded with the requirements of the minimum air changes per hour. The application of passive solar chimney can shut off the air-conditioner automatically when outside temperature is lower than at 28°C. Comparing to the traditional design of conference hall which consumes 42032kWh, the application of this study can decrease the energy consumption to 32515 kWh. The energy consumption of the air-conditioner reduces about 25.6% per year.