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1
Kingdon, Lorraine B. "Hot Water Issues." College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/295533.
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Eriksson, Mimmi. "Corrosion and microfluidics in hot water microsystems." Thesis, Uppsala universitet, Mikrosystemteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-207573.
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This thesis addresses some important issues when designing microfluidic systems for hot pressurized water. The properties and behavior of water at elevated temperatures and in micro scale is briefly reviewed, and opportunities and possible problems of using hot pressurized water in microfluidic devices are brought up. Experimental work was focused on corrosion resistance for commonly used microsystem materials in hot pressurized water, and the microfluidic behavior for hot pressurized water. An experiment system was successfully designed, assembled and used for corrosion resistance experiments in hot pressurized water. Corrosion resistance tests were performed for some common materials used in microfluidic and microsystems (silicon, stainless steel grade 304, silicon carbide, aluminum nitride, aluminum oxide, soda-lime glass and borosilicate glass) in deionized water and in low concentration HCl (0.1 mM) at two different temperatures (180oC and 270oC). All of the tested materials, except soda-lime glass, showed a good overall performance in the low temperature range. In the high temperature range, all materials showed signs of corrosion to some extent. Severe damages and high corrosion rates were observed for silicon and the two glasses, and stainless steel 304 showed signs of pitting corrosion. A microfluidic study identified some major issues needed to be overcome to make future microfluidic studies with hot pressurized water possible. Important observations included the importance of a short traveling distance for a hot micro flow to avoid rapid cooling, and to choose a suitable dye to avoid particles clogging thin capillaries and micro channels.
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Thetadig, Rita Ah Wa. "Factors in the Adoption of solar Domestic Hot water Systems in Brisbane (SEQ)." Thesis, Griffith University, 2009. http://hdl.handle.net/10072/367095.
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The economical, technological and environmental viability of Solar Domestic Hot Water (SDHW) technology is well established. Its potential role as a major contributor to meeting residential hot water needs is the view promoted in this research and the major reason why it is taken up by users. There is also a need to explore the barriers preventing a household’s adoption of Solar Domestic Hot Water (SDHW), particularly in Queensland, the “Sunshine State” of Australia. This research is based on eight hypotheses, suggesting factors that may be related to the household decision to adopt solar. A household survey collected data to test the hypotheses in an effort to explain underlying factors that influence the pattern of household take-up as evident in Brisbane, South East Queensland. The research identified the following factors as important to the adoption of solar domestic hot water:
1. Newspapers/magazines and personal recommendations by friends and relatives are key sources of information that households access when making a decision on SDHW;
2. There are five other factors which help explain both organizational subsystems and behavioral subsystems as having a relationship with household adoption of SDHW. These are: factors related to energy suppliers, operating factors, government initiatives (specifically SDHW Rebate), environmental issues; namely attractiveness of the system because solar energy is renewable and socio-economic factor such as the presence of ‘Other’ household residents in occupational groups, in particular, managers and administrators;
3. The findings offer evidence to enhance issues already identified in previous work and pursued in the current research on SDHW in Queensland (Berrill 1991), which identifies socio-political and environmental issues, as two of the three issues relating to “Quality of life”. The third economic issue is also looked at in this research.
4. New findings are evident in support of interrelationships’ between socio-political, energy supply systems and technological awareness factors, namely Government Rebate, Energy Supplier and Operating Factors and the household decision to adopt SDHW;
5. The findings offer an explanation as to why technological factors pertaining to SDHW and factors involved in assessing satisfaction with the system have been misunderstood. The results clearly indicate an overwhelming satisfaction with the SDHW system;
6. This research contributes to the body of research in this area, especially as it puts forward evidence of why socio-economic characteristics of household’s are a fundamental aspect in understanding the adoption of SDHW. It provides households’ perspectives to the identified issues that directly affect them. These perspectives can then be incorporated into the identification, development and implementation of public and private energy policy.Thesis (Masters)
Master of Philosophy (MPhil)
Griffith School of Environment
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Cohen, R. R. "Thermal energy accumulation in stratified hot water stores." Thesis, Cranfield University, 1986. http://hdl.handle.net/1826/4195.
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Hot water thermal energy stores have the potential to improve and
extend the performance of many kinds of energy system. Waperature
stratification in the store is likely to affect the system's
efficiency. A basic but accurate computer model of the hot water
store under various inlet flow conditions is a requisite means of
assesiing promising applications of hot water storage by system
computer simulation techniques.
A microprocessor-controlled test facility has been constructed to
evaluate the performance of a 3m
3
hot water store under a wide range
of inlet flow conditions, using a temperature step input approach.
Three types of inlet/outlet ports have been examined: horizontal,
vertical and distributors. The results show that two distinct
regions evolve within the store: a fully-mixed region adjacent to
the inlet port and a region of smooth 'plug-flow' in the remaining
volume of the store. The performance of the store is shown to be
defined by the initial depth of the fully-mixed region which in turn
is seen to be closely related to the buoyancy and momentum fluxes of
the inlet flow.
The behAviour of the store and the evident correlations have enabled
a one-dimensional computer model of the store to be developed, taking
into account the turbulent mixing, vertical heat conduction and heat
losses to the surrounding areas. The model has been successfully
validated against the results from the step input experiments.
The model has been integrated into a computer simulated central
heating system which incorporates a hot water store. Predictions have
been made, using the simulation, of the energy savings which may be
achieved with the use of storage in comparison to a conventional
system, and an assessment has been made of the economic viability of
the application.
5
Mote, R. T. "Heat exchanger design in a hot-water store." Thesis, Cranfield University, 1991. http://dspace.lib.cranfield.ac.uk/handle/1826/10999.
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The behaviour of natural convective buoyancy-driven flows within
a hot-water store due to the forced passage of colder water
through the heat-exchanger's pipe are reviewed in the light of
recent advances in experimental
throughout the literature. The
exchanger designs, for natural
unworkable for the engineer
complication arises because the
heat exchanger are sensitive to
and numerical studies, reported
empirical development of heat
convection problems, are often
with a specification. The
heat transfer performance of the
the initial boundary conditions
of the problem, ranging from the initial charged temperature of
the water in the insulated tank of a fixed
dimensíon, to the
physical properties of the heat-exchanger's pipe. It was
concluded that an improvement in the heat transfer performance
can be derived by determining the optium length and the
orientation of the
heat-exchanger's arrangement. Further benefits
are derived by correlating the thermal convective behaviour,
within the hot-water store, with the forced passage of colder
water through the heat exchanger's pipe. A convective flow model,
based upon the experimental results, is described to advance the
heat
exchanger design principles in the situation of transient
natural convection. Assumptions employed in the experimental work
confirm that realistic and reasonable results can be obtained
from the thermal analysis of the vertical cylindrícal store in
two-dimensions.
6
Catherine, Quinton Shaun. "Effective geyser management through intelligent hot water usage profiling." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1094.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009This study presents an intelligent Hot Water Cylinder (HWC) usage profiling system to provide peak demand side management and improve HWC efficiency in a typical household. In this research HWCs will be referred to as geysers. Research was done into various techniques available to improve energy efficiency in South Africa, as well as the different sectors South Africa's electricity supplier, Eskom, has highlighted where improvements in energy efficiency can be made. From this it was decided to refine the scope of the project to the residential sector, and more importantly geyser. A typical geysers operation and power consumption was researched and analysed to determine where efficiency improvements could be made. A system was required that would reduce the amount of energy consumed by the geyser, and provide the consumer with hot water at the same time. Based on the research it was decided to design a profile based geyser controller. The profiling system comprised of a PIC microcontroller, four digital temperature sensors and a time keeper used to determine individually based hot water usage profiles for the home. The profile was based on three parameters, namely the frequency (repetitiveness) of hot water being drawn, the length of the draw period, and the time of day when the water was drawn. Once the profile had reached a 90% accuracy, the profile implemented itself. Based on the profile, the controller then regulated the temperature of the geyser according to the demand of the household, without manual intervention. If the household's routine were changed, the profile would adapt itself accordingly. The controller is therefore fully intelligent and continues to refine the profile on a day to day basis. By introducing the profile based controller, the monthly average geyser temperature was reduced, reducing the amount of standing losses, which in torn reduced the total amount of energy consumed by the geyser. The profile controller was designed to aid in the reduction of the energy demand of geysers on the power grid. This will benefit both the consumer as well as Eskom, as Eskom will have a reduced power load, and the consumer will have a reduced electricity bill. The results of the experiments are shown, as well as a comparison between calculated versus measured results, to justify the accuracy of the calculations.
7
Kronholm, Juhani. "Utilization of pressurized hot water and supercritical water in the treatment of polluted water and soil." Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/kemia/vk/kronholm/.
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Bjorn, Andrew. "Enhanced removal of residual DNAPL with hot water injection." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/MQ53369.pdf.
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Kwan, F. S.-Y. "Deadleg losses from a simulated domestic hot water system." Thesis, University of Canterbury. Mechanical Engineering, 1985. http://hdl.handle.net/10092/8080.
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This report considers the factors determining the deadleg losses of horizontal 'supply' hot water copper pipes, in a dynamic simulation rig of a domestic hot water system in the laboratory of the Mechanical Engineering Department at the University of Canterbury.
In order to simulate the calculated system daily deadleg losses for a real house for which the ambient te1nperature was low* and the room temperature was l8°C, an air-conditioning unit was used to supply cool air blowing through the five sections of 75 mm ID PVC air 'tunnels' which were built over the horizontal 'supply' hot water copper pipes [photo 1].
Thus the effect of deadleg losses due to natural-convection heat transfer in an ordinary domestic house was simulated experimentally by using forced-convection heat transfer in the rig.
Quantitative values of deadleg losses at different usage patterns and tank temperatures are tabulated.
*5.7°C as ambient temperature was being used in this project. It was the most severe daily average temperature of Christchurch in July (1960-1969) - data from Meteorological Office at the airport of Christchurch, New Zealand.
10
Salazar, Navalón Pablo. "EVALUATION OF HEAT LOSSES FROM ADOMESTIC HOT WATER CIRCULATIONSYSTEM." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-20044.
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Heat losses are an important problem in domestic hot water circulation systems. Therefore, toreduce these losses becomes an issue of utmost importance both economically andenvironmentally. Nevertheless, it has not been until recent years when these losses have beenstudied further. Commonly studies have focused on the heat space system operation or radiatorsystem. This study focuses on heat losses in the domestic hot water circulation through thepiping system in a building at a school located in Gävle (Sweden) using non-destructive flowand temperature reading devices. The heat used by the school is provided by the district heatingnetwork that feeds several heat exchangers. The heat losses, at the same time, will be comparedwith simulation and theoretical procedures to corroborate them. The domestic hot water pipingsystem of this study consists on more than 1200 meters of insulated copper pipes with differentdiameters and different insulation thickness. The system was measured for one week (April 26,2015 to May 3, 2015) when there are working days and nonworking days. A 5% of the annualdistrict heating consumption in the school was calculated as heat losses in the domestic hotwater circulation system in the building studied. Finally, improvements in insulation system andchanges in the domestic hot water temperature have been simulated and they demonstrate thatsavings of up to 35% of the heat losses can be achieved and produce significant energy savings.
11
Altorkmany, Lobna. "Energy Efficient Eradication of Legionella in Hot Water Systems." Licentiate thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-67514.
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Disease related to unsafe water, poor sanitation, and lack of hygiene is some of the most common causes of illness and death all around the world. Since the first detection of Legionella in Philadelphia 1976, Legionella is recognized to cause Legionellosis which is associated with two distinct forms: Legionnaires’ disease and Pontiac fever. The fact that vaccination against Legionella disease is not efficacious enhances the effort towards developing the existence disinfection methods and inventing new technologies. Re-colonization of Legionella in hot water systems may occur within a few days or weeks after disinfection since conventional disinfection methods significantly reduce but do not eliminate pathogens. Understanding the conditions favoring Legionella occurrence in hot and cold systems will aid in developing new treatment technologies that minimize or eliminate human exposure to legionella pathogens. The work introduces the Anti-Bact Heat Exchanger (ABHE) system as a new innovative system inspired by nature. Compared to conventional disinfection methods, the ABHE system proposed to achieve continuous thermal disinfection of bacteria in hot water systems and in simultaneously saving energy and reducing the required costs. Thermodynamic analysis, experimental test and simulation validation of the ABHE by the Engineering Equation Solver (EES)-based model were achieved to define the thermal performance of the ABHE system at given operation conditions. The experimental test shows high potential of recovering heat and thus saving energy by the ABHE system. In addition, pumping power (PP) was relatively small compared to the recovered heat which implies that less energy was required compared to the recovered heat. The effect of working parameters such as temperatures and flow rate on the thermal performance of the ABHE system was furthermore investigated. The study shows that supplied water temperature has similar effects as the disinfection temperature. Namely, increasing supplied water temperature enhances the regeneration ratio (RR) but it requires a large plate heat exchanger (PHE) area and PP. On the contrary, increasing the temperature in use results in a reduced PHE area and PP. Flow rate has the greatest influence on the thermal performance of the ABHE system. Increasing flow rate leads to an increase in the required area of the PHE. The EES-based model investigated the effect of the length and the width of the plates used in the PHE on the RR and the required area of the PHE. Then, the EES-based model was used to optimize the ABHE system in which the PHE area is minimized or the RR of the ABHE system is maximized.
12
Gjerde, Oddbjorn. "Impressed current cathodic protection of solar hot water tanks." Thesis, Gjerde, Oddbjorn (2014) Impressed current cathodic protection of solar hot water tanks. Other thesis, Murdoch University, 2014. https://researchrepository.murdoch.edu.au/id/eprint/23515/.
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“This project is concerned with investigating the use of impressed current cathodic protection (ICCP) to protect domestic tanks. ICCP is a technique used in large industrial installations, such as those in the mining and oil and gas industries, and uses an electrical potential to impede the electrochemical reaction that leads to corrosion. Given a continuous source of electrical energy this approach operates indefinitely, without any maintenance.” (Lee, 2014) This document provides guidelines as to what must be done and where to look for answers as well as delivering suggestions to the design.
13
Cataldi, Francesco. "Management Optimization of Energy Consumption Reduction for Residential Hot Water." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2995.
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The objective of this thesis is to create an automatic water management system capable of optimizing the usage of warm water stored in two water tanks to reduce the monthly energy consumption of the instant water heater installed in a residential house. This system is called Water Mixing System (WMS). The two heat sources considered are: PV-T system and heat rejected by the air condition system. The PV-T system is a new technology that allows transformation of the sun radiation into both electricity and warm water, increasing the efficiency of the panel compared to either a common photovoltaic panel or solar collector. The air-conditioning heat source, instead, recovers the heat rejected by the condenser to the environment by employing a heat exchanger that stores the heat collected in the water tank.
14
Liu, Chun. "Modeling of water and lubricant sprays in hot metal working." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196091214.
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Jones, Sophia Christina Acle. "Micro-cogeneration optimal design for service hot water thermal loads." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16016.
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JAYASINGHE, B. T. D. "ENERGY SAVING METHODS IN HOT WATER SUPPLY FOR HOSPITALITY INDUSTRY." Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190810.
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Hotel Industry in Sri Lanka is becoming a vital sector in the economic development in the after the cessation of ethnic conflict that existed in almost 30 years. This has resulted in high demand for energy for enhanced activities in the hotel industry. The prime objective of the hospitality industry is to provide maximum comfort and facilities to its customers. Hence, Hotels utilize more energy to satisfy its visitors which will benefit the hotel as well as the income generated through foreign exchange to the country. Electrical energy is used in this industry for lighting, air conditioning (cooling), water purification, hot water and steam for washing, cleaning and cooking purposes etc. In Sri Lanka, electricity is generated mainly from fossil fuels. Furnace oil is used in boilers for heating of water and supply of steam for laundry, kitchen and washing for guest rooms. If thermal power generation with the use of fossil fuels is to be dominated in meeting energy demand, it will be a heavy burden to the country since Sri Lanka being a developing country lacks much needed foreign exchange. Burning of Fossil fuel will also affect the environment by releasing green house gases to the atmosphere as well. Therefore, it has to explore alternative sources of energy in order to meet the demand for energy in the hotel sector as much as possible. Further, sustainable use of energy is very vital for sustained development of the country at large. In this project, a comprehensive study was carried to identify the opportunities to minimize the energy utilized in hospitality institutes. It has been identified that around 22% of the total energy consumption in a hotel is for hot water generation, which is higher than energy used for cooling and lighting. Hence the amount of energy utilized for hot water production in a selected beach hotel was evaluated and alternative source of energy such as solar hot water system was studied, which could be utilized in order to minimize energy consumption though burning fossil fuel. A comprehensive study in designing the total solution in solar hot water system was undertaken with the available data with the selected hotel. A simulation was carried out to test the validity of solution with software packages Polysun , Kolektor 2.2 , SAM2010 and RETScrean. The proposed system of solar hot water is expected to save SLR 781,200. (Approximately 5,400.00 USD) per year and reduce emission of CO2 by 33 Tons per year.Hotellindustrin i Sri Lanka är en viktig del av den ekonomiska återhämtningen efter den 30-åriga krigsperioden i landet. Detta har resulterat i en stor efterfråga för energi för att kunna tillgodose en hög standard till turisterna. Hotellens ökade energianvändning tillfredsställer besökarna i en större grad som i sin tur leder till högre vinster. Elenergi används inom denna industri för belysning, luftkonditionering, vattenrening, tappvärmevatten och ånga för tvättning, städning osv. Eltillförseln i Sri Lanka är i huvud sak fossilbaserad. Fossilolja förbränns i pannor för olika varmvattenändamål. Om termisk kraftgenerering med fossila bränslen fortsätter att utnyttjas i så stora skala kommer Sri Lanka att drabbas ännu mer ekonomisk i framtiden på grund av oljeimporten. Miljön också påverkas negativt genom ökade utsläpp av växthusgaser. Därmed behöver man undersöka alternativa energikällor för att möta energibehoven i hotellsektorn. Dessutom bidrar förnybara energikällor till landets hållbar utveckling. Detta projekt omfattar en övergripande studie för att identifiera möjligheter för energibesparingar i Sri Lankas hotellindustri. Undersökningen visar att cirka 22% av hotellens energianvändning går åt varmvatten, vilken är en högre andel än energibehoven för komfortkyla och belysning. Varmvattenanvändning i ett strandhotell utvärderades och alternativa energikällor som solvärme studerades. Solvärmesystem designades i detalj med tillgängliga data. Simuleringar genomfördes med kommersiella mjukvaror som Polysun, Kolektor 2.2, SAM2010 och RETScreen. Det utvalda systemet förväntas leda till en årlig besparing på SLR 781,200 (circka 5,400 USD) och årlig CO2-minskning på 33 tonne.
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Herbstein, Tom Philip. "Insurance and the Anthropocene: like a frog in hot water." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16571.
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Includes bibliographical referencesThis thesis explores the relationship between the commercial insurance industry, global environmental change (GEC) and what Beck (1992; 1999) termed the 'risk society'. In recent decades, there have been growing concerns that many of the risks impacting contemporary society have undergone fundamental changes. Many of these risks are increasingly being linked to the unintended consequences of humankind's remarkable progress in science and technology, and have been described as debounded, given that they so often transcend both geographical and temporal boundaries (Beck 1992). Within the risk society, the commercial insurance industry - which relies on statistical (actuarial) analysis to help it assess and manage its risk exposure - has been described as demarcating the frontier barrier between bounded (i.e. insurable) and debounded (i.e. uninsurable) risk. However, this claim has been a highly contested one, leading to calls for more empirical data to help clarify how commercial insurance is actually responding under conditions of uncertainty. Of all the debounded risks, GEC has emerged as one of the risk society's most recognisable. Now understood to be a result of the anthropogenic emission of greenhouse gasses, particularly since the onset of the industrial revolution, its impacts have risen so sharply in recent decades that it has prompted claims that Earth has moved away from the era of the Holocene and into the Anthropocene (Crutzen 2002). Given that at least 40% of the cost of environmental catastrophes is now borne by commercial insurance, GEC provides an excellent opportunity to gain a deeper understanding of how the industry is responding to debounded risk at the risk society's frontier barrier. Early commentators suggested that the commercial insurance industry would be well motivated to respond proactively to GEC, by taking a more mitigative approach to managing its drivers at both the global and local levels. However, the industry, so far, has been described as more adaptive of its own business activities than mitigative. This raises questions about whether such claims are true across all three of the insurance industry's activities - as risk carriers, risk managers and as investors, why they have responded in such ways, and what implications this has for broadening our understanding of the complex relationship between commercial insurance, debounded risk and the risk society's frontier barrier. To consider these questions, a collective case study was undertaken with a variety of commercial insurance companies, re-insurers, asset managers, clients, brokers, industry associations and regulators across South Africa, Germany, Switzerland, the United Kingdom and Belgium. The research identified how commercial insurers have indeed responded more by adaptation of their business activities than mitigation of the drivers of GEC. This is mainly through the use of defensive underwriting to help them manage their exposure. However, the research extends this analysis by highlighting some of the nuances of the industry's response. This includes its focus on centralisation, the influence of the existing paradigm framing its understanding of risk, and by highlighting the irony that the area of insurers' activities, initially believed to be most suited for responding to GEC (i.e. their investment portfolios), have, in practice, been the area recording the least response. In exploring why this is so, the study draws on understandings of the Anthropocene to argue that commercial insurers are finding their existing risk assessment tools progressively out-dated in a world where risk is no longer as predictable as it once was. This is further compounded by increasingly plural access to the risk society's science and technologies, which, in some instances, are undermining the role commercial insurance plays as society's primary financial risk manager. This raises questions around the role commercial insurance plays in demarcating the risk society's frontier barrier which, ultimately, has far broader implications for why so many of society's institutions are struggling to adapt to risk in the 21st Century.
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Pitarch, i. Mocholí Miquel. "High capacity heat pump development for sanitary hot water production." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/81858.
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Heat pumps have been identified as an efficient alternative to traditional boilers for the production of sanitary hot water (SHW). The high water temperature lift (usually from 10ºC to 60ºC) involved in this application has conditioned the type of used solutions. On the one hand, transcritical cycles have been considered as one of the most suitable solutions to overcome the high water temperature lift. Nevertheless, the performance of the transcritical CO2 heat pump is quite dependent on the water inlet temperature, which in many cases is above 10ºC. Furthermore, performance highly depends on the rejection pressure, which needs to be controlled to work at the optimum point in any condition. On the other hand, for the subcritical systems, subcooling seems to be critical for the heat pump performance when working at high temperature lifts, but there is not any published work that optimizes subcooling in the SHW application for these systems. Therefore, the subcritical cycle should require a systematic study on the subcooling that optimizes COP depending on the external conditions, in the same way as it has been done for the rejection pressure in the transcritical cycle.
The aim of this thesis is to investigate the role of subcooling in the performance of a Propane water-to-water heat pump for SHW production, in the application of heat recovery from any water source. Two different approaches to overcome the high degree of subcooling were designed and built to test them in the laboratory:
1) Subcooling is made at the condenser: The active refrigerant charge of the system is controlled by a throttling valve. Subcooling is controlled independently at any external condition.
2) Subcooling is made in a separate heat exchanger, the subcooler. Subcooling is not controlled, it depends on the external condition and the heat transfer at the subcooler.
The heat pumps were tested at different water temperatures at the evaporator inlet (10ºC to 35ºC) and condenser inlet (10ºC to 55ºC), while the water production temperature was usually fixed to 60¿C. The obtained results have shown that COP depends strongly on subcooling. In the nominal condition (20¿C/15¿C for the inlet/outlet water temperature at the evaporator and 10ºC/60ºC for the inlet/outlet water temperature in the heat sink), the optimum subcooling was about 43 K with a heating COP of 5.61, which is about 31% higher than the same cycle working without subcooling. Furthermore, the system with subcooling has been proved experimentally as being capable of producing water up to 90¿C and has shown a higher COP than some CO2 commercial products (catalog data reference).Las bombas de calor han sido identificadas como una alternativa eficaz a las calderas tradicionales para la producción de agua caliente sanitaria (ACS). El elevado salto de temperatura del agua que normalmente tiene lugar en esta aplicación (por lo general de 10ºC a 60ºC) ha condicionado el tipo de soluciones que se utilizan. Por un lado, los ciclos transcríticos han sido considerados como una de las mejores soluciones para trabajar con los elevados saltos de temperatura del agua. Sin embargo, el rendimiento de la bomba de calor transcrítica con CO2 es bastante dependiente de la temperatura de entrada del agua, que en muchos casos está por encima de los 10¿C. Además, el rendimiento depende en gran medida de la presión de descarga, la cual necesita ser controlada con el fin de trabajar en el punto óptimo en cualquier condición externa. Por otra parte, para los sistemas subcríticos, el subenfriamiento parece ser crítico para el buen funcionamiento de la bomba de calor cuando se trabaja con elevados saltos de temperatura del agua, pero no hay ningún trabajo publicado en el que optimicen el subenfriamiento para la aplicación de ACS en estos sistemas. Por lo tanto, los sistemas subcríticos requieren de un estudio sistemático para buscar el subcooling óptimo y maximizar el COP en función de las condiciones externas, de la misma forma que se ha hecho para la presión de descarga en los ciclos transcríticos. El objetivo de esta tesis es investigar el papel del subenfriamiento en el rendimiento de una bomba de calor trabajando con Propano para la producción de ACS, en la aplicación de recuperación de calor de cualquier fuente de agua (agua- agua). Dos enfoques diferentes para superar el alto grado de subenfriamiento fueron diseñados y construidos para ponerlos a prueba en el laboratorio: 1) El subenfriamiento se hace en el condensador: La carga activa de refrigerante del sistema se controla con una válvula de estrangulación. De esta manera, el subenfriamiento puede ser controlado de forma independiente a cualquier condición externa. 2) El subenfriamiento se hace en un intercambiador de calor separado, el subenfriadador. El subenfriamiento no se controla, este depende de la condición externa y de la transferencia de calor en el subenfriadador. Las bombas de calor se ensayaron a diferentes temperaturas del agua a la entrada del evaporador (10ºC a 35ºC) y entrada del condensador (10ºC a 55ºC), mientras que la temperatura de producción de agua, normalmente, se fija a 60¿C. Los resultados obtenidos han demostrado que el COP depende mucho del subenfriamiento. En las condiciones nominales (20ºC/15ºC para la temperatura del agua de entrada/salida en el evaporador y 10ºC/60ºC para la temperatura del agua de entrada/salida en el condensador), el subenfriamiento óptimo fue aproximadamente de 43 K con un COP de calentamiento de 5,61, que es alrededor del 31% más alto que el mismo ciclo trabajando sin subenfriamiento. Además, el sistema con subenfriamiento ha probado de forma experimental, que es capaz de producir agua hasta los 90ºC, y ha mostrado un COP más alto que algunos productos comerciales que trabajan con CO2 (datos de referencia del catálogo).
Les bombes de calor han estat identificades com una alternativa eficaç a les calderes tradicionals per a la producció d'aigua calenta sanitària (ACS). L'elevat salt de temperatura de l'aigua que normalment té lloc en aquesta aplicació (en general de 10ºC a 60ºC) ha condicionat el tipus de solucions que s'utilitzen. Per una banda, els cicles transcrítics s'han considerat com una de les millors solucions per tal de treballar amb els elevats salts de temperatura de l'aigua. No obstant això, el rendiment de la bomba de calor transcrítica amb CO2 és bastant dependent de la temperatura d'entrada de l'aigua, que en molts casos està per damunt de 10¿C. A més, el rendiment depèn en gran mesura de la pressió de descarrega, la qual necessita ser controlada per tal de treballar en el punt òptim a qualsevol condició externa. Per altra banda, per als sistemes subcrítics, el sub-refredament sembla ser crític per al funcionament de la bomba de calor quan es treballa amb elevats salts de temperatura de l'aigua, però no hi ha cap treball publicat en el qual optimitzen el sub-refredament per a l'aplicació d'ACS en aquests sistemes. Per tant, els sistemes subcrítics requereixen d'un estudi sistemàtic per tal de buscar el subcooling òptim i maximitzar el COP en funció de les condicions externes, en la mateixa forma que s'ha fet per la pressió de descarrega en els cicles transcrítics. L'objectiu d'aquesta tesi és investigar el paper del sub-refredament en el rendiment d'una bomba de calor treballant amb Propà per a la producció d'ACS, en l'aplicació de recuperació de calor de qualsevol font d'aigua (aigua-aigua). Dos enfocaments diferents per tal de superar l'alt grau de sub-refredament van ser dissenyats i construïts per posar-los a prova en el laboratori: 1) El sub-refredament es fa en el condensador: La càrrega activa de refrigerant del sistema es controla amb una vàlvula d'estrangulació. D'aquesta manera, el sub-refredament pot ser controlat de forma independent en qualsevol condició externa. 2) El sub-refredament es fa en un intercanviador de calor separat, el sub-refredador. El sub-refredament no es controla, este depèn de la condició externa i de la transferència de calor al sub-refredador. Les bombes de calor es van assajar a diferents temperatures de l'aigua a l'entrada de l'evaporador (10ºC a 35ºC) i a l'entrada del condensador (10ºC a 55ºC), mentre que la temperatura de producció d'aigua, normalment, es fixa a 60¿C. Els resultats obtinguts han demostrat que el COP depèn molt del sub-refredament. En les condicions nominals (20ºC/15ºC per a la temperatura de l'aigua d'entrada/eixida a l'evaporador i 10ºC/60ºC per a la temperatura de l'aigua d'entrada/eixida en el condensador), el sub-refredament òptim és aproximadament de 43 K amb un COP d'escalfament de 5,61, que és al voltant del 31% més alt que el mateix cicle treballant sense sub-refredament. A més, el sistema amb sub-refredament ha provat de forma experimental, que és capaç de produir aigua fins als 90ºC, i ha mostrat un COP més alt que alguns productes comercials que treballen amb CO2 (dades de referència del catàleg).
Pitarch I Mocholí, M. (2017). High capacity heat pump development for sanitary hot water production [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/81858
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Nguyen, Bao The. "Feasibility of solar hot water and distillation systems in Vietnam." Thesis, Nguyen, Bao The (1998) Feasibility of solar hot water and distillation systems in Vietnam. PhD thesis, Murdoch University, 1998. https://researchrepository.murdoch.edu.au/id/eprint/52389/.
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This thesis studies the feasibility of solar hot water and distillation systems in Vietnam. The first part of the work involved investigating the available solar radiation data for Vietnam and developing procedures for producing hourly solar radiation and ambient temperature sequences for use in simulation studies.
Two versions of the modified Angstrom formula were developed from long term records of measured monthly mean daily global solar radiation and sunshine hour values obtained from twelve meteorological stations across Vietnam. These formulae were then used to estimate solar radiation for additional stations where only sunshine records were available. The results from these two formulae were compared with those from eight other commonly used correlations between solar irradiation and sunshine duration. The distribution of the solar radiation throughout the country was then summarised in the form of monthly solar radiation maps, a useful approach for those interested in assessing the potential for the application of solar energy in Vietnam.
A computer model to generate hourly solar radiation and ambient temperature sequences from monthly average daily radiation values, or monthly average daily sunshine hour data, and monthly average daily temperature values, was developed. This model can be used for a tropical country like Vietnam to overcome the difficulty of the scarcity of hourly solar radiation data for use in simulation packages. The resulting model was tested in a number of ways.
A single purpose, user-friendly simulation program for solar hot water systems (SHWS) in Vietnam, called VIETSIM, was developed. This program has been validated by comparing the results of this program with those from the well-known TRNSYS program and is shown to be highly reliable. The feasibility of SHWS in Vietnam is studied for both the domestic and commercial sectors. For the domestic sector, the analysis focuses on medium size families in three locations, representing the main climatic types in this country. For the commercial sector, a case study of a hotel - office building is used as an indicator of the feasibility in this sector.
The development of SOLSTILL, a simulation program for estimating the performance of basin type solar stills is described. Models for both the standard free convection solar still and a forced convection solar still with enhanced heat recovery were included in the program. The design, fabrication and testing of an experimental system set up at Murdoch University Energy Research Institute to validate SOLSTILL is detailed. The comparison of experimental and simulation results indicates that the program can predict distillate production at an acceptable level of accuracy. The results from a sensitivity analysis of SOLSTILL involving varying weather, design and operational parameters are also presented. The feasibility of such solar distillation applications in Vietnam is investigated through the use of the SOLSTILL program in a case study.
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Mohd, Shafie Zainun. "Mechanism and kinetics of cellobiose decomposition in hot-compressed water." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/748.
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This thesis reports some insight into fundamental chemistry of cellobiose decomposition in hot-compressed water (HCW). This includes the effect of mild temperature, initial cellobiose concentration, weakly acidic condition and AAEM chlorides on decomposition behaviour of cellobiose. The new knowledge provides fundamental understanding on decomposition mechanisms of sugar oligomers into monomers and other products. Such knowledge is also essential to understanding the decomposition behaviour of more complex cellulose and biomass conversion in HCW.
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Abebe, Yibekal Alemayehu. "Managing the soil water balance of hot pepper (Capsicum annuum L.) to improve water productivity." Thesis, University of Pretoria, 2010. http://hdl.handle.net/2263/25257.
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A series of field, rainshelter, growth cabinet and modelling studies were conducted to investigate hot pepper response to different irrigation regimes and row spacings; to generate crop-specific model parameters; and to calibrate and validate the Soil Water Balance (SWB) model. Soil, climate and management data of five hot pepper growing regions of Ethiopia were identified to develop irrigation calendars and estimate water requirements of hot pepper under different growing conditions. High irrigation regimes increased fresh and dry fruit yield, fruit number, harvest index and top dry matter production. Yield loss could be prevented by irrigating at 20-25% depletion of plant available water, confirming the sensitivity of the crop to mild soil water stress. High plant density markedly increased fresh and dry fruit yield, water-use efficiency and dry matter production. Average fruit mass, succulence and specific leaf area were neither affected by row spacing nor by irrigation regimes. There were marked differences among the cultivars in fruit yields despite comparable top dry mass production. Average dry fruit mass, fruit number per plant and succulence were significantly affected by cultivar differences. The absence of interaction effects among cultivar and irrigation regimes, cultivars and row spacing, and irrigation regimes and row spacing for most parameters suggest that appropriate irrigation regimes and row spacing that maximize productivity of hot pepper can be devised across cultivars. To facilitate irrigation scheduling, a simple canopy cover based procedure was used to determine FAO-type crop factors and growth periods for different growth stages of five hot pepper cultivars. Growth analysis was done to calculate crop-specific model parameters for the SWB model and the model was successfully calibrated and validated for five hot pepper cultivars under different irrigation regimes or row spacings. FAO basal crop coefficients (Kcb) and crop-specific model parameters for new hot pepper cultivars can now be estimated from the database, using canopy characteristics, day degrees to maturity and dry matter production. Growth cabinet studies were used to determine cardinal temperatures, namely the base, optimum and cut-off temperatures for various developmental stages. Hot pepper cultivars were observed to require different cardinal temperatures for various developmental stages. Data on thermal time requirement for flowering and maturity between plants in growth cabinet and open field experiments matched closely. Simulated water requirements for hot pepper cultivar Mareko Fana production ranged between 517 mm at Melkassa and 775 mm at Alemaya. The simulated irrigation interval ranged between 9 days at Alemaya and 6 days at Bako, and the average irrigation amount per irrigation ranged between 27.9 mm at Bako and 35.0 mm at Zeway.Thesis (PhD)--University of Pretoria, 2010.
Plant Production and Soil Science
unrestricted
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Zurawlew, Michael. "Post-exercise hot water immersion : a novel approach to heat acclimation." Thesis, Bangor University, 2018. https://research.bangor.ac.uk/portal/en/theses/postexercise-hot-water-immersion(107af32f-9f52-4474-b47b-0d6344185b88).html.
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Hot environmental conditions can reduce work productivity/exercise performance and increase the incidence of exertional heat illness. In preparation for hot environments, individuals commonly complete heat acclimation protocols that initiate physiological and perceptual adaptations to reduce thermal strain and improve physical capabilities. However, conventional exercise-heat acclimation interventions can be costly and impractical, as they require access to an artificial hot environment and often require control of core temperature during exercise. As such, there is a demand for a flexible heat acclimation intervention that can be easily incorporated into the daily training of athletes and military/occupational personnel. Therefore, the aim of this thesis was to develop a novel and practical post-exercise hot water immersion heat acclimation protocol. Firstly, 6-days of submaximal exercise in temperate conditions followed by a hot water immersion induced hallmark heat acclimation adaptations during submaximal exercise in temperate and hot conditions and improved endurance exercise performance in the heat (Chapter 4). The initiated adaptations were also not specific to the clock-time of when heat exposures occurred (Chapter 5). Post-exercise hot water immersion also initiated hallmark heat acclimation adaptations in both endurance trained and recreationally active individuals (Chapter 6). In addition, the decay of the induced adaptations following post-exercise hot water immersion is slow, with no observable loss of heat acclimation two weeks following the cessation of the protocol (Chapter 7). The studies presented in this thesis demonstrate that the novel post-exercise hot water immersion intervention provides heat acclimation and reduces thermal strain during exercise in the heat. Future research is required to optimise this technique to improve its incorporation into different military/occupational or athlete scenarios and assess the impact of the intervention on the incidence of exertional heat illness.
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Cemo, Thomas A. Van Treuren Kenneth W. "Design and validation of a solar domestic hot water heating simulator." Waco, Tex. : Baylor University, 2009. http://hdl.handle.net/2104/5357.
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Brazeau, Randi Hope. "Sustainability of Residential Hot Water Infrastructure: Public Health, Environmental Impacts, and Consumer Drivers." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26537.
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Residential water heating is linked to the primary source of waterborne disease outbreaks in the United States, and accounts for greater energy demand than the combined water/wastewater utility sector. To date, there has been little research that can guide decision-making with regards to water heater selection and operation to minimize energy costs and the likelihood of waterborne disease.
We have outlined three types of systems that currently dominate the marketplace: 1) a standard hot water tank with no hot water recirculation (STAND), 2) a hot water tank with hot water recirculation (RECIRC), and 3) an on-demand tankless hot water system with no hot water recirculation (DEMAND).
Not only did the standard system outperform the hot water recirculation system with respect to temperature profile during flushing, but STAND also operated with 32 – 36% more energy efficiency. Although RECIRC did in fact save some water at the tap, when factoring in the energy efficiency reductions and associated water demand, RECIRC actually consumed up to 7 gpd more and cost consumers more money. DEMAND operated with virtually 100% energy efficiency, but cannot be used in many circumstances dependent on scaling and incoming water temperature, and may require expensive upgrades to home electrical systems.
RECIRC had greater volumes at risk for pathogen growth when set at the lower end of accepted temperature ranges, and lower volumes at risk when set at the higher end when compared to STAND. RECIRC also tended to have much lower levels of disinfectant residual (40 -850%), 4-6 times as much hydrogen, and 3-20 times more sediment compared to standard tanks without recirculation. DEMAND had very small volumes of water at risk and relatively high levels of disinfection.
A comparison study of optimized RECIRC conditions was compared to the baseline modes of operation. Optimization increased energy efficiency 5.5 – 60%, could save consumers 5 – 140% and increased the disinfectant residual up to 560% higher disinfectant residual as compared to the baseline RECIRC system. STAND systems were still between 3 – 55% more energy efficient and could save consumers between $19 - $158 annual on water and electrical costs. Thus, in the context of “green” design, RECIRC systems provide a convenience to consumers in the form of nearly instant hot water, at a cost of higher capital, operating and overall energy costs.Ph. D.
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Asim, Muhammad. "Experimental Analysis of Integrated System of Membrane Distillation for pure water with solar domestic hot water." Thesis, KTH, Energiteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141141.
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In GCC countries, especially in UAE desalination of sea water is considered to be one of the most effective and strategic alternative for satisfying the current and future demand of water for domestic purposes. The depletion of ground water aquifers, rapid industrial development and increase of urban population in UAE lead to tremendous increase in fresh water demand during past decade. Although, desalinated fresh water is supplied to the consumers by local municipalities, people in the region rely mostly on bottled water for drinking purpose obtained through post desalination re-processing. Thousands of suppliers in UAE deliver bottled water to homes or offices thus leading to environmental unsustainability in the whole conversion chain from desalinated water to bottling, packaging and delivery. In fact, UAE is one of the leading countries in per capita bottle water consumption. Therefore, a need has been observed to provide safe drinking water for households in a sustainable way.In order to produce drinking water at homes, a concept of integrating Membrane Distillation (MD) based water purification with Solar Domestic Hot Water (SDHW) systems has been proposed and its feasibility has been evaluated in this research study. Present application is for a single family house/villa in UAE region that requires 20 l/day of drinkable water and 250 l/day of hot water for domestic purpose. An experimental pilot system has been installed at CSEM-uae for evaluating different operational parameters of such integrated system and also to determine overall thermal performance of the system. The study provides detailed design of experimental unit, procurement, installation and commissioning of the SDHW-MD integrated system along with estimated annual profiles of pure water and overall energy consumption.Experiments performed for one month during summer and distillate fluxes of around 4.5 – 12 l/m2/hour has been obtained with optimum MD hot and cold side flow rates of 6 and 3 l/min respectively and at hot side temperatures ranging from 50 - 70oC with cold side average temperature of 35oC. With recovery of cold side heat of MD unit, 25% of daily demand of DHW could be reduced and hence the estimated annual combined energy demand of 8220 kWh could be sufficiently fulfilled with either 8.5 m2 aperture area of Flat plate solar thermal collectors or with 7.5 m2 of Evacuated tubular collectors.
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Bierbrauer, Frank. "Mathematical modelling of water-droplet impact on hot galvanised steel surfaces." School of Mathematics and Applied Statistics - Faculty of Informatics, 2004. http://ro.uow.edu.au/theses/400.
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Hot-dip galvanising is commonly used in industry to increase the corrosion resistance of cold-rolled steel products for commercial use such as roofing and walling of buildings. Traditionally, the zinc coated steel surface is characterised by a relatively smooth surface with large spangle relief which is detrimental to corrosion resistance. One of the techniques to modify the surface appearance consists of a water-mist spray solution which allows for the creation of a large number of nucleation sites giving rise to micro rather than macro spangles, thereby producing a much smoother surface. In addition, controlling the spray parameters allows the hot, zinc coated, steel surface to be ‘roughened’ facilitating its bonding to concrete or for lamination. The proper control of water droplet impact parameters such as impact velocity, droplet diameter and crater size is essential for a successful implementation of this technique. Certain aspects of the second of these processes, the production of rough, non-skid galvanised steel sheet surfaces, has been addressed by this thesis.Although an experimental investigation of the effect of such water droplet parameters on the formation of zinc surface characteristics such as crater diameter and depth would provide a great deal of valuable data it is fraught with difficulties. The presence of hot metal surfaces exceeding 450oC and the boiling and evaporation of water droplets taking place at very small timescales (microseconds) all combine to make an experimental study difficult to implement not to say unsafe. On the other hand computer simulations with a properly constructed mathematical model are a valuable tool for the investigation of these parameters.A comprehensive modelling of the process would include the process of heat transfer: such as conduction through a vapour layer, internal droplet and vapour convection, radiation from the hot surface, solidification of the zinc liquid layer; as well as the fluid dynamical aspects: such as surface tension at the droplet-air, droplet-zinc and zinc-air interfaces, the droplet impact phenomena such as spreading and splashing and the formation of impact craters and wave propagation in a thin viscous zinc layer. As a first stage in the modelling exercise this thesis will concentrate on an investigation of single water droplet impact on a thin liquid zinc layer with a steel substrate which provides a simplified and computationally tractable model of the spraying process.The objectives of this thesis are twofold: firstly, the development and construction of an accurate, robust mathematical model and, secondly, the solution of the model for the impact of a single water droplet onto a thin liquid layer of zinc on a steel substrate. This model must be able to deal with rapidly deforming moving interfaces and maintain stability in the presence of very large density and viscosity ratios. This moving boundary problem requires the tracking of three fluid interfaces while also maintaining incompressibility. The Godunov-Marker-Particle Projection Scheme developed in this thesis is able to satisfy these requirements. Through a combination of approximate projection methods, Godunov convective differencing, Marker-Particle interface tracking and velocity filters the method is able to treat viscous, multi-fluid free surface flows. The modelling of free surface flows with more than two separate immiscible fluids, to the author’s knowledge not yet published in the literature, is a secondary aim of the thesis. A major part of the thesis deals with the thorough testing of each aspect of the combination of numerical methods used: firstly, the Poisson solver with discontinuous coefficients and homogeneous boundary conditions used in the approximate projection method, analytical solutions for the construction of an initial solenoidal velocity field, testing of the projection and velocity filters and kinematic tests of the Marker-Particle method for tracking of fluid interfaces; secondly, dynamical tests of the viscous incompressible Navier-Stokes equations for: an exact solution, the Lid-Driven Cavity and the Rayleigh-Taylor instability. The combined method is also successfully tested on the limited two-fluid droplet-solid and droplet-liquid impact problems before solving the thesis problem.It is shown that, for the impact of a single water droplet onto a thin liquid zinc layer, impact crater growth, diameter and depth, are linearly dependent on impact velocity. For a given impact velocity, crater diameter is not effected by increasing zinc layer depth although crater depth is linearly dependent. The time at which the droplet commences penetration of the zinc layer is inversely dependent on impact velocity and the maximum crater diameter and depth are nonlinearly dependent on impact velocity. The model shows that, within the convective timescale, droplet impact on thin liquid zinc layers can be approximately described by droplet spreading on a solid zinc surface. The droplet is shown to spread preferentially to the zinc layer splashing after completion of spreading. This shows that adjustment of the droplet impact velocity or zinc layer depth can vary the surface roughness appropriately.
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Salazar, Navalón Pablo. "Evaluation of heat losses from a domestic hot water circulation system." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-20042.
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Heat losses are an important problem in domestic hot water circulation systems. Therefore, to reduce these losses becomes an issue of utmost importance both economically and environmentally. Nevertheless, it has not been until recent years when these losses have been studied further. Commonly studies have focused on the heat space system operation or radiator system. This study focuses on heat losses in the domestic hot water circulation through the piping system in a building at a school located in Gävle (Sweden) using non-destructive flow and temperature reading devices. The heat used by the school is provided by the district heating network that feeds several heat exchangers. The heat losses, at the same time, will be compared with simulation and theoretical procedures to corroborate them. The domestic hot water piping system of this study consists on more than 1200 meters of insulated copper pipes with different diameters and different insulation thickness. The system was measured for one week (April 26, 2015 to May 3, 2015) when there are working days and nonworking days. A 5% of the annual district heating consumption in the school was calculated as heat losses in the domestic hot water circulation system in the building studied. Finally, improvements in insulation system and changes in the domestic hot water temperature have been simulated and they demonstrate that savings of up to 35% of the heat losses can be achieved and produce significant energy savings.
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Vorobieva, Ekaterina. "Valorization of grape pomace residues integrating hot compressed water with biotechnology." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10819.
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Armstrong, Peter Michael. "Enhancing the energy storage capability of electric domestic hot water tanks." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:af140a2c-aab4-4fc9-8709-6f9474079cd5.
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Electric hot water tanks play a pivotal role as demand response assets within the UK's energy system by storing heat when energy is inexpensive and delivering domestic hot water when it is required. This role will become increasingly important if non-dispatchable renewable energy sources are to play a bigger part in the energy mix. Historically, the design standards relating to hot water tanks have focused primarily on minimising heat losses. However, in addition to preserving energy, a hot water tank should preserve the availability of heat above a useful temperature for as long as possible to avoid energy usage during peak times when it is costly or carbon intensive. To do this, thermal stratification within hot water tanks must be promoted. Unfortunately, thermal stratification leads to conditions that are conducive to bacterial growth due to the hospitable temperatures that arise during operation. For this reason, question marks have arisen over the extent to which more flexible control strategies, designed to allow for increasing penetrations of intermittent renewable energy sources, might lead to the growth of pathogenic bacteria within hot water tanks. The objective of the work discussed in this thesis was to understand the extent to which there is a conflict between thermal stratification and bacterial growth in practice, whether this conflict can be resolved and the potential implications for electric hot water tanks operating on a time of use tariff. A small field study demonstrated that there is prolific bacterial growth within conventional electric cylinders and that this can be attributed to thermal stratification with a confidence of (P<0.01). Fitting a de-stratification pump, to enhance sanitary performance, resulted in a 19% decrease in the recovery of useable hot water above 43°C. Given that the tanks tested during the field study were made of copper, the consequences of alternative material choices on thermal performance were explored. It was found that the rate of useable hot water loss, due to de-stratification associated with thermal diffusion across the thermocline, could be reduced by a factor of 2.7 by making the tank liner wall from stainless steel instead of copper. Further numerical work indicated that this improvement in stratifying performance was most significant for small tanks with high aspect ratios. In addition to de-stratification that arises due to vertical conduction, de-stratification due to inlet mixing was reduced by up to 30% by installing a spiral diffuser into the base of a test cylinder. In addition, by lowering the immersion heating element to ensure there is sufficient heat transfer to the base of the cylinder, sterilising temperatures could be attained throughout the stored volume of water in the tank during heating. This showed that the conflict between thermal and sanitary performance within electric tanks could potentially be resolved. A bespoke tank, made from stainless steel and fitted with a diffuser, was built and subjected to typical draw cycles that reflect real world operation. These tests showed that more useable hot water could be delivered in comparison to a commercial off the shelf copper tank and consequently the utilisation of the Economy 7 time of use tariff would be enhanced.
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Karwa, Nitin. "Experimental Study of Water Jet Impingement Cooling of Hot Steel Plates." Phd thesis, tuprints, 2012. https://tuprints.ulb.tu-darmstadt.de/3041/1/PhD_Thesis_Karwa.pdf.
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Liquid jet impingement cooling is critical in many industrial applications. Principle applications include extracting large heat flux from metal parts, such as hot fuel bundle post-loss-of-coolant-accident in nuclear reactors, heat treatment of steel plates post-hot-processing, etc. The ability of liquid jets to extract high heat flux at controlled rates from metal parts, with temperatures as high as 800-1000 ºC, at moderate flow rates has made them indispensable in these applications. Due to the complexity of the process, the mechanism of flow boiling heat transfer during jet impingement cooling is not well understood. Resultantly, the presently used design approaches are based more on experience and rule of thumb than science. The principle challenge in the study of jet impingement cooling for these high temperature applications has been the lack of reliable instrumentation for measuring the cooling rates. To add to this, the conjugate nature of boiling heat transfer, especially on low conductivity metal like steel, makes this problem very complicated to understand. Thus, much of the state of art on this subject has been limited to experiments where either the conjugate problem has not been addressed or the tests have been performed at temperatures that are much lower than in the above mentioned applications.
The basic objective of the present work is to contribute to the understanding of the thermo-hydrodynamic phenomenon occurring during the cooling of a hot steel plate with an impinging water jet. This work also complements a parallel study being conducted at the Institute of Fluid Mechanics and Aerodynamics (Technische Universität Darmstadt), in which the complex transport processes are being treated theoretically and validated against the experimental results of this work.
To achieve the objective, transient cooling experiments have been performed on an instrumented stainless steel AISI-type 314 cylinder. To measure the temperature variation within the stainless steel cylinder during the transient cooling, fast-response thermocouples have been embedded within holes that are precisely drilled though its bottom flat face. The cylinder is induction heated to a homogeneous initial temperature of 900 ºC and is subsequently cooled by means of an axisymmetric subcooled free-surface water jet that impinges on its top flat face (impingement surface). During the cooling, each thermocouple output has been recorded at the rate of 100 samples per second. A two-dimensional axisymmetric inverse heat conduction analysis using these measured temperature data has been performed to estimate the temporospatial variation of temperature and heat flux on the impingement face. Both low and high speed images have been recorded to visualize the two-phase flow. These images and the estimated heat transfer distribution are used to understand the boiling mechanism. The effect of jet parameters, namely subcooling and impingement velocity, on the heat transfer process has been studied. Additionally, the effect of spent liquid accumulation over the impingement surface has been studied in few exploratory plunging jet experiments.
This study presents a systematic methodology for the measurement and estimation of the temporospatial variation of heat transfer on the impingement surface of a hot steel plate. Three distinct regions, with difference in the extent of liquid-wall contact, have been identified on the impingement surface from the recorded images.
i) A wetted region surrounds the jet stagnation region. Nucleate boiling is the principle heat transfer mode in this region. The outer periphery of this region is called the wetting front. No boiling activity has been observed in the high speed images, most likely because the bubbles were small and were unable to reach the liquid free-surface. The maximum heat flux position is determined to be within this region. As the wetted region grows in size with time, the maximum heat flux position also moves radially outwards. The wetting front and maximum heat flux position velocity reduce with increasing radial distance from the impingement point because the liquid velocity and subcooling reduce at the wetting front. Likewise, the wetting front velocity increases with jet velocity and subcooling.
ii) The liquid gets deflected at the wetting front due to the efflux of large vapor bubbles beyond the maximum heat flux position. A term ``wetting front region' has been coined in this thesis to describe this region. The width of this region could not be determined from the high speed images. Transition boiling within a thin superheated liquid film that is continuously replenished by the bulk flow is proposed to be the probable reason for the high heat flux in this region. Further, the radial heat conduction to the wetted region is also significant here.
iii) The impingement surface outside the wetting front region is dry. The dry surface slowly cools down due to film boiling and radial heat conduction to the wetting front region. The film boiling rate is very low in the impingement region. After deflecting away from the impingement surface in the wetting front region, the liquid film breaks into droplets over this region. Looking from the side, droplet deflection angle is observed to be small; still these droplets do not come into direct contact with the impingement surface, as has been confirmed by looking down from the top.
The velocity of the splashed droplets has been determined by analyzing the high speed images. It has been found that the drop velocity is much lower than the liquid film velocity calculated at the wetting front position using single-phase flow relations suggested by Watson. It has been hypothesized that the liquid film in the wetted region is decelerated by the bubbles growing on the impingement surface. Further, measurements reveal that the drop velocity increases with decreasing subcooling, which means that the film and the droplet are accelerated in the radial outward direction by the vapor released in the wetting front region.
It has been shown that the rewetting temperature (analogous to the Leidenfrost temperature for a sessile droplet), which refers here to the temperature below which the direct liquid-wall contact is re-established and the heat flux increases, in both the impingement and radial flow regions is significantly higher than that reported in the literature for pool boiling. Removal of bubbles by the flowing liquid in the early stages of their growth and then their rapid condensation within the subcooled liquid avoids the buildup of vapor near the hot wall, which is the likely reason for the enhancement of the rewetting temperature. This observation confirms that high heat fluxes can be removed at large wall superheats by impinging liquid jets, as practiced in the industry.
The boiling curve shifts to higher heat flux and superheat with the increase in the jet velocity and subcooling. The maximum heat flux and surface temperature at maximum heat flux increase with both the jet velocity and subcooling. Area-weighted average boiling curves have been determined, which clearly show the enhancement in the heat transfer with jet velocity over the average surface superheat of 100 to 800 K. The enhancement in jet subcooling is, however, noticeable only in the wall superheat range of 300 to 700 K. The maximum heat flux and surface temperature at maximum heat flux decrease with radial distance from the stagnation point before reaching a constant value. The radial distribution of maximum heat flux condition has been classified into three regions based on the relative size of the hydrodynamic/thermal boundary layer and the liquid film.
In the plunging jet impingement studies, it has been found that the wetting front growth slightly slows down due to accumulation of the spent liquid over the impingement surface. Area-weighted average boiling curves show that the heat transfer reduces due to accumulation.
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Othman, Timothy. "Water, energy and heat balances of sheep exercising in hot conditions." Thesis, Othman, Timothy (1997) Water, energy and heat balances of sheep exercising in hot conditions. PhD thesis, Murdoch University, 1997. https://researchrepository.murdoch.edu.au/id/eprint/51676/.
Full textAbstract:
The aim of the project was to improve the understanding of water, energy and heat stresses on livestock grazing out from water sources in semi-arid environments. To do this, water, energy and thermal balances were studied on shorn and unshorn sheep during exercise and rest in thermoneutral and hot conditions.
Initially, water and energy turnovers and thermoregulatory responses of animals of various fleece lengths were determined indoors while they exercised on a treadmill. Heat production at rest was virtually constant whereas during exercise it increased 2-3 fold. During exercise, unshorn sheep reached higher rectal temperatures, respiratory frequencies and evaporative heat and water losses than shorn animals. Thermoregulatory responses increased in the heat, but lack of solar radiation made direct applicability to field conditions uncertain. A second laboratory trial studied the effects of drinking saline or fresh water on fluid intake, osmoregulation and thermoregulation. Saline intakes did not impair thermoregulatory responses of animals.
Under field conditions, the effects of high-or low-protein food intakes on tritiated water turnover, voluntary water intake, live-weight and grazing patterns were measured in commercial flocks grazing lupin or cereal stubble. The lupin diet may have induced greater water turnover and weight gain, and led to more concentrated grazing around the water point. For undetermined reasons grazing of cereals occurred more at the margins of the paddock. A second set of field measurements examined the effects of exercise and rest, and of long and short fleeces; both exercise and short fleece led to greater water turnover. with cereal grazing again being greatest at a distance from water.
Finally, these data were used to calculate probable energy and water balances of sheep grazing semi-arid pastures. The emergent patterns were compared with existing models of grazing (from CSIRO), and of thermal balances (from the University of Nottingham). In moderate environments data were in close agreement, but some large differences under field conditions indicated that mathematical modelling of livestock performance, though useful, needs further development.
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Guarnieri, Raniero Alberto. "Novel approaches to the design of domestic solar hot water systems." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16056/1/Raniero_Guarnieri_Thesis.pdf.
Full textAbstract:
Domestic solar hot water units, if properly designed, are capable of providing all hot water needs in an environmentally friendly and cost-effective way. Despite 50 years of development, commercial technology has not yet achieved substantial market penetration compared to mainstream electric and gas options. Therefore, alternate designs are warranted if they can offer similar or greater performance for a comparable cost to conventional units. This study proved that such alternatives are possible by designing and testing two novel solar hot water systems (SHWS). The first system used compound parabolic collector (CPC) panels to concentrate solar energy and produce steam. The steam moved from a rooftop downward into a heat exchange pipe within a ground level water tank, heating the water, condensing and falling into a receptacle. The operation was entirely passive, since the condensate was pulled up due to the partial vacuum that occurred after system cooling. Efficiencies of up to 40% were obtained. The second system used an air heater panel. Air was circulated in open and closed loop configuration (air recycling) by means of a fan/blower motor and was forced across a compact heat exchanger coupled to a water tank. This produced a natural thermosiphon flow heating the water. Air recycling mode provided higher system efficiencies: 34% vs. 27%. The concurrent development of an analytical model that reasonably predicted heat transfer dynamics of these systems allowed 1) performance optimisation for specific input/starting operating conditions and 2) virtual design improvements. The merit of this model lay in its acceptable accuracy in spite of its simplicity. By optimising for operating conditions and parameter design, both systems are capable of providing over 30 MJ of useful domestic hot water on clear days, which equates roughly to an increase of 35°C in a 200 L water tank. This will satisfy, on average, daily hot water requirements for a 4-person household, particularly in low-latitude regions (eg. Queensland). Preliminary costing for these systems puts them on par with conventional units, with the passive, remotely coupled, low maintenance, CPC SHWS comparable to higher end models. The air heater SHWS, by contrast, was much more economical and easier to build and handle, but at the trade-off cost of 1) the need for an active system, 2) increased maintenance and running costs and 3) the requirement for a temperature control mechanism that would protect the panel body by dumping hot air trapped inside if stagnation were to occur.
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Guarnieri, Raniero Alberto. "Novel Approaches to the Design of Domestic Solar Hot Water Systems." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16056/.
Full textAbstract:
Domestic solar hot water units, if properly designed, are capable of providing all hot water needs in an environmentally friendly and cost-effective way. Despite 50 years of development, commercial technology has not yet achieved substantial market penetration compared to mainstream electric and gas options. Therefore, alternate designs are warranted if they can offer similar or greater performance for a comparable cost to conventional units. This study proved that such alternatives are possible by designing and testing two novel solar hot water systems (SHWS). The first system used compound parabolic collector (CPC) panels to concentrate solar energy and produce steam. The steam moved from a rooftop downward into a heat exchange pipe within a ground level water tank, heating the water, condensing and falling into a receptacle. The operation was entirely passive, since the condensate was pulled up due to the partial vacuum that occurred after system cooling. Efficiencies of up to 40% were obtained. The second system used an air heater panel. Air was circulated in open and closed loop configuration (air recycling) by means of a fan/blower motor and was forced across a compact heat exchanger coupled to a water tank. This produced a natural thermosiphon flow heating the water. Air recycling mode provided higher system efficiencies: 34% vs. 27%. The concurrent development of an analytical model that reasonably predicted heat transfer dynamics of these systems allowed 1) performance optimisation for specific input/starting operating conditions and 2) virtual design improvements. The merit of this model lay in its acceptable accuracy in spite of its simplicity. By optimising for operating conditions and parameter design, both systems are capable of providing over 30 MJ of useful domestic hot water on clear days, which equates roughly to an increase of 35°C in a 200 L water tank. This will satisfy, on average, daily hot water requirements for a 4-person household, particularly in low-latitude regions (eg. Queensland). Preliminary costing for these systems puts them on par with conventional units, with the passive, remotely coupled, low maintenance, CPC SHWS comparable to higher end models. The air heater SHWS, by contrast, was much more economical and easier to build and handle, but at the trade-off cost of 1) the need for an active system, 2) increased maintenance and running costs and 3) the requirement for a temperature control mechanism that would protect the panel body by dumping hot air trapped inside if stagnation were to occur.
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Azar, Marc. "The influence of energy use visualization on the energy consumption in municipal multi-apartment buildings : The case of Nynäshamnbostäder." Thesis, KTH, Byggvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103894.
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This thesis investigates the influence of energy visualization on hot water consumption, as well as builds up the framework for the analysis of electricity consumption, of multi-apartment buildings in Sweden, . 115 apartments in Nynäshamn have been scheduled to be equipped with feedback visualization, through the use of television sets, allowing the monitoring of electricity and hot water consumption on a monthly basis. One year of consumption data prior to this feedback introduction was acquired for statistical analysis. The results were then displayed and analysed, allowing for the composition of a generalized conclusion whilst revealing the need for further investigation and future work. To achieve this end, clustering was performed on the 115 apartments according to the following characteristics: Number of tenants per apartment, Area of the apartment, Location of the apartment, and age of the tenants. Principal Component Analysis was used to select dominant characteristics, through eliminating highly correlated components, after which trend analysis was performed on each of the separate clusters revealing a seasonal change model. Finally, a Multivariate Analysis of Variance utilized on the paired clusters to identify any significant change, along with post-analysis tests to specify the groups in which significant change was detected, is presented to be applied in future work. The preliminary results clearly show that the characteristic data can be grouped into three distinct clusters of which the consumption trend of hot water consumption is distinct. Moreover the data reveals a correlation between the apartment’s characteristics and its hot water consumption. However further monitoring and data collection will be required before any strong trend can be identified, as well as power analysis will have to be applied to conclude any significant change. Nonetheless the initial results demonstrate promising signs that ought to be further investigated in the future. 2
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Yannakis, Nicholas Brian. "Economic optimisation of domestic solar hot water for the commercial market using consol evacuator tube panels in Christchurch, New Zealand." Thesis, University of Canterbury. Mechanical, 2012. http://hdl.handle.net/10092/10196.
Full textAbstract:
Domestic solar hot water is becoming a more common technology used specifically with the residential market of New Zealand. Recently domestic solar hot water systems have been economically identified as an option in commercial applications. Commercial building owners in the corporate world generally base decisions on economic reasons, therefore this research investigates the need to economically optimise the size of domestic solar hot water systems for eight separate commercial applications within Christchurch. All modelling has been completed using Consol’s heat pipe evacuator tube panels orientated North at an angle of 45 degrees.
The TRNSYS simulation program is utilised to model the domestic solar hot water system in the eight commercial applications. Each commercial application has a unique domestic hot water load profile. The heat pipe evacuated tube is locally available from Consol New Zealand Limited. A common proportional relationship was utilised to define the relationship between the size of the storage tank and area of solar panels, which enables a range of domestic solar hot water system sizes to be used in the simulations.
A proportional relationship is identified to economically optimise the size of commercial domestic solar hot water systems in Christchurch. This proportional relationship enables engineers and designers of commercial domestic hot water systems to confidently implement domestic solar hot water system designs. This provides an economically optimal solution in regards to the size of the solar component that should be installed during the rebuild of Christchurch.
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Roy, Siddhartha. "Interplay of Water Chemistry and Entrained Particulates in Erosion Corrosion of Copper and Nonleaded Alloys in Potable Water Systems." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82668.
Full textAbstract:
Erosion corrosion of plumbing materials in domestic water systems is a complex phenomenon driven by water quality, hydrodynamic and electrochemical factors. Erosion corrosion accounts for over a third of copper hot water system failures in the U.S., hundreds of millions in damage, and may be expected to increase with newer Legionella control strategies including increased use of water recirculation and high temperatures. Additionally, some nonleaded alloys introduced after the passage of a new federal law restricting lead content in plumbing, have been anecdotally implicated as failing prematurely from erosion corrosion compared to traditional alloys.
This dissertation includes 1) a critical review of the literature, 2) investigation of a recent rapid erosion corrosion failure in a large building plumbing system, 3) replication of this phenomena in copper and nonleaded brass in laboratory studies, and 4) evaluation of 12 nonleaded alloys against conventional leaded brass. Current plumbing codes and guidelines to prevent erosion corrosion were found to be widely inconsistent and lacking scientific evidence. Large-scale recirculating hot water pipe-loop experiments demonstrated that an aggressive hard water with entrained aragonite (CaCO3) particles could cause fully penetrative failures (i.e., leaks) in brand new copper pipe and nonleaded brass fittings in just 3-49 days. This represents the first time rapid erosion corrosion failures have ever been replicated in the laboratory under conditions similar to those encountered in practice. The entrained particulates dramatically accelerated attack on metals, especially at pipe bends. In general, lowering pH, increasing flow velocity, increasing temperatures, entrainment of particles (of bigger sizes), and addition of chlorine disinfectant increased erosion corrosion rates. These results scientifically proved that hard waters are not inherently less aggressive than soft water, and in fact if CaCO3 solids form they can be much more aggressive. Finally, cavitation and erosion corrosion resistance of 12 nonleaded alloys was evaluated against leaded brass; stainless steels demonstrated superior performance, silicon brass had the greatest susceptibility and remaining alloys were in the middle. This performance data can aid decision making regarding choice of alloys for various water applications.
Our work over the years, including involvement in the Flint Water Crisis, demonstrated that practicing trustworthy science as a public good requires commitment to scientific rigor, truth-seeking, managing conflicts of interest, and comprehensible evidence-based science communication. Critical problems in 21st century public science were highlighted including perverse incentives, misconduct, postmodernist "science anarchist" thought, and ineffectiveness of U.S. water utilities in communicating tap water safety to the American public.Ph. D.
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Bellamy, Joanna Kate. "Recovery of surfactant-induced friction reduction in a closed hot water system." Thesis, University of Ottawa (Canada), 2000. http://hdl.handle.net/10393/8794.
Full textAbstract:
In the 1980's the use of surfactants to decrease pumping energy requirements in district heating systems was explored in Europe. FRAs are particularly attractive for district energy systems because they have long pipe runs and the associated pumping costs can be a large component of total operating costs. In this research project, a series of obstructing devices were designed and tested for their ability to disrupt micelles and reverse the friction reducing effect in a 3/4 inch diameter stainless steel experimental test loop. Four simple obstructing geometries were investigated: a central obstruction blocking one quarter of the flow area, a central obstruction blocking half of the flow area and two obstructions which blocked the area close to the pipe wall, blocking one half and three quarters of the flow area, respectively. The experimental friction reducing additive was a combination of a quaternary ammonium surfactant, Ethoquad O/12, and a 3-hydroxy-2-naphthoate counterion, at concentrations of 1600 ppm and 800 ppm respectively. The obstructions were tested at three temperatures, 70, 50 and 40 Celsius and at flow rates of 3.7, 3.0 and 2.0 m./s. (Abstract shortened by UMI.)
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Bellamy, Joanna. "Recovery of surfactant-induced friction reduction in a closed hot water system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/MQ58443.pdf.
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Zhao, Yongjun. "The cooling of a hot steel plate by an impinging water jet." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060316.150622/index.html.
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Norman, Alice Jane. "Investigation and simulation of hot water use and production in farm dairies." Thesis, University of Plymouth, 1988. http://hdl.handle.net/10026.1/1985.
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The dairy farming sector of European Agriculture is currently under considerable economic pressure so the aim of each farmer should be to produce saleable milk, at the lowest cost. One important area of concern is the expenditure on hot water for hygiene, as to be acceptable to the buyer the milk must have a low level of contaminants. Clean milk is produced from clean, healthy udders by means of equipment which is adequately and appropriately cleaned. To facilitate this hygienic milk production most dairies are eguipped with heaters to provide water at 40°C (for cleaning udders) and 80- 100°C (for plant cleaning). The practice of udder washing is a subjective process as it depends on the operator's judgement of a 'clean' udder and his view of necessity. In England and Wales there are two only accepted methods of plant cleaning, circulation cleaning and Acidified Boiling Water (A. B. W.). Prior to the. audit described it was expected that water and electricity consumption for plant cleaning would be predictable. To date there has been little information on the volume and temperature of water used on commercial dairy farms and the electricty consumed to produce this hot water. It is therefore difficult for farmers to make informed judgement on methods of reducing their electricity costs. Thirteen farms in South Devon have been monitored, to establish current practice: farmers were questioned about their water use; electricity and water consumption were metered for two years; and cleaning practices were observed. This survey has revealed that many non-standard cleaning methods are used on dairy farms, making the prediction of water and electricity consumption difficult. The management of equipment has been revealed as the most important aspect in determining the energy used. A computer model has been produced to simulate water heating in the farm dairy, which can be used to advise farmers as to the energy cost of their cleaning practices. This model has .been successfully used on several of the farms surveyed, on one farm its use resulted in energy savings in excess of 400 kWh per month.
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詹仕榮. "Development of Parallel Hot Water Heater System forLarge Flow of Hot Water." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/v4au97.
Full textAbstract:
碩士建國科技大學
電機工程系暨研究所
107
Traditional water heaters are frequently found to be unable to provide sufficient water supply and maintain temperature instability. The thesis develops a high-volume water heater parallel system to cope with this problem. First, multiple cool water storage tanks are employed to store enough cool water. Next, the control valve is activated to heat cool water, when heated is to a setting temperature, the water is then transported to the hot water tank for storage. Finally, the needed heated water is delivered to the faucet or shower nozzle. To prevent instability of temperature and water output, this product employs three devices including an anti valve, a temperature sensor and an alarming lamp. The backflow barrier is employed to keep water backflow, the temperature sensor is adopted to detect temperature signal, and the alarming lamp shows the status of the heater. The empirically made water heater is credited with maintaining stability of water supply and temperature on the one hand, and interchangeability and life of the water heater on the other hand. Besides, the whole design can make us to understand the knowledge which related to physics, material science and electrical engineering.
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Wilken, Andries Stephan. "Customer-orientated hot water load management." Diss., 2001. http://hdl.handle.net/2263/26229.
Full textAbstract:
Please read the abstract in the section 00front of this documentDissertation (MEng (Electrical Engineering))--University of Pretoria, 2007.
Electrical, Electronic and Computer Engineering
MEng
unrestricted
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Muya, T. M. "Hot water consumption in South Africa." Thesis, 2012. http://hdl.handle.net/10210/7265.
Full textAbstract:
M.Ing.A one-year investigation on hot water consumption was conducted in South African developed and developing communities of Johannesburg to determine the personal and household average daily consumption of hot water as well as the average hourly (in summer and in winter) and monthly patterns. The motivation for this research project was to provide to engineers and water heaters manufacturers reliable experimental data on hot water consumption from various categories of dwellings. The existing sources of information in South Africa being extremely limited and results of estimations. The necessary information was collected from hourly and monthly measurements taken by monitoring hot water systems in different dwellings including, houses (300 units), traditional houses (90 units), shacks (200 units), apartments (123 units), townhouses (90 units). For the purpose of this study, the selected (not statistically) dwellings were classified into three categories, which are: high-density dwellings representing the developing communities, medium-density and low-density dwellings which represent the developed communities. The results of measurements show that, in general, people living in developed communities (low-density dwellings) use at least 1.4 times more hot water than those of developing communities (high-density dwellings). The patterns of hot water consumption have been determined for monthly and hourly consumption. The former is divided in four sections: summer weekdays, winter weekdays, summer weekends and winter weekends. The differences between sections are the specific times of peaks and the consumption. The results of this study should be of great assistance to engineers and water heaters designers in analysing existing systems for performance improvement, and in sizing more efficient and suitable systems to South African use.
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Schaefer, Paul Jeffery. "Modeling of solar domestic hot water systems." 1991. http://catalog.hathitrust.org/api/volumes/oclc/24232135.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1991.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 209-212).
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Alemayehu, Yibekal Abebe. "Managing the soil water balance of hot pepper (Capsicum annuum L.) to improve water productivity /." 2009. http://upetd.up.ac.za/thesis/available/etd-06042010-234306.
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WU, CHIEN-FENG, and 吳建鋒. "A hot water service systems with remote controllers." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/s3h7ha.
Full textAbstract:
碩士南開科技大學
電子工程研究所
105
As electronic technology changes rapidly, there is still much to be improved for old products with the introduction of new technologies, materials and processes. With regards to water heater, not only constant temperature controlled by microprocessor, the remote controller is also designed for adjusting temperature conveniently, so each member of the family can set the temperature easily on demand. In this paper, we propose a ZigBee based remote controller for water heater, which is a pilot study for commercialization. By analyzing the wired remote control interface and functions, we replace it by ZigBee based controller, so the water heater will compliance with the sensor device requirements of IoT (Internet of Things) and be integrated to smart home network via a routable ZigBee based remote controller.
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Lin, Ray-Chen, and 林睿誠. "Wind Solar System For Heat Pump Hot Water." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/00448232986018400423.
Full textAbstract:
碩士國立高雄應用科技大學
電機工程系博碩士班
104
Nowadays, with the environmental problem such as imminent exhaustion of fossil energy and increasingly serious global warming make the concept of environmental protection about energy conservation and carbon emission reduction has been taken seriously, and many energy-saving systems have been proposed in various fields with the trend of energy conservation and carbon emission reduction. Furthermore, there are a lot of energy-saving technologies and patents of hot water heater.Currently the energy-saving water heaters on market are generally related to a single system products. Taking solar water heaters as example, those solar water heaters still need to rely on auxiliary heating (electrical heating or gas water heater) in the rainy days, so it will lose the meaning of energy-saving concept.Therefore,we replace the consumptive auxiliary electrical heating into energy-saving air source heat pump water heater and combine the heat pump water heater with the solar energy. The combined system become the student’s patent and make up deficiencies of solar energy to double the energy-saving effect. In addition, at the same time we combine the solar heat pump with wind vertical generator to create a true zero energy of energy-regeneration water heating systems.
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Malkin, Mark P. "Design of thermosyphon solar domestic hot water systems." 1985. http://catalog.hathitrust.org/api/volumes/oclc/13292851.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1985.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 107-109).
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Chiang, Chih-Cheng, and 蔣志政. "Taiwan Hot Spring Survey and Water Quality Analysis." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/55911565587317781427.
Full textAbstract:
碩士嘉南藥理科技大學
溫泉產業研究所
99
ABSTRACT This study focused on the assessment of Hot Spring and its water quality in Taiwan. In statistics, there is around a hundred hot springs all over the country. In this research, around fifty hot springs were subjected to monitoring. In assessing the water quality, pH, temperature, conductivity, mineral content, total dissolved solids, and ORP were monitored. Samples were brought into the laboratory for analysis. The plants surrounding the hot spring have also been surveyed. This is to contribute for further assessment of the hot spring. Mineral content like Mg2+, Ca2+, Cu+, Fe2+, Fe3+, Cr3+, K+, Na+, HCO3-, HCO3- ,and major cations and anions like Cl- and SO42- were analyzed using and Inductively Coupled Plasma – Optical Emission Spectra (ICP-OES) and Ion Chromatography (IC), respectively. Hot springs are also classified into five categories. They are (1) According to pH Ranges, which is related to the major cations or anions present in the water, (2) Cationic, (3) Anionic, (4) Abundant Mineral Content, and (5) Others. It has also been found out that certain hot springs are abundant of specific minerals like Mg, Na, etc., and their combinations. The abundance of the minerals is related to the topography of the area. With the above classification, hot springs were given names. The mineral, to which it is abundant, will be its name. Also, based from these classifications, specific applications of each hot spring can now be known. With this knowledge of hot spring, the use of it can now be optimized. Keyword: hot Spring, assessment, hot spring quality
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Hsu, Jui-Liang, and 徐瑞良. "The Study of Water Resources Managementfor Hot Spring Area and Releasing of Tea Essential Oil from Microcapsules in Hot Spring Water." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/07935261516795268479.
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博士大葉大學
生物產業科技學系
103
1. A Study of Developing Strategy of Szuchungshi Obtains and Provides Hot Spring Business The purposes of this study were to establish key success factors and develop the strategy for Szuchungshi Obtains and Provides Hot Spring Business. Since there is a need to supply hot spring water for Szuchungshi hot spring area, a public system should be established for total water volume control and the recycle of the hot spring water to strengthen business performance and achieve the goal of sustainable operations. In this study, the in-depth interview, literature review, Delphi technique and Analytic Hierarchy Process (AHP) were utilized to collect and analyzed qualitative and quantitative data. A total of 16 experts and 9 scholars were included in the panel group for in-depth interview and questionnaire survey. The selection of qualified experts in the panel was based on the criteria of professionals with over three years of experience in hot spring related business from government, industry and academics. The AHP results revealed key success factors of developing hot spring business in two levels, the first level had six factors and the second, 30 factors. In the The production factor (weighting factor = 0.3021, C.R. value = 0.0782) was the most important one among the first level factors. Important factors among the second level included: the government policy on ‘consulting the hot spring industry to assist the resources development’ (weighting factor = 0.2797), opportunity factor of ‘increasing awareness of health promotion by hot spring’ (weighting factor = 0.0937), production factor of ‘increasing of potential tourist numbers’ (weighting factor = 0.1501), requirement factor of ‘support of development (maintenance) of natural resources from the local government’ (weighting factor = 0.3307), industrial strategy and competitive situation on ‘improvement of hardware and software quality’(weighting factor = 0.4002) and related and supporting industry factor on ‘transportation resources’ (weighting factor = 0.3329). In summary, the results of this study suggested several new concepts of sustainable management and strategy for hot spring industry development to achieve the long term goal of sustainable operations of hot spring resources. Keyword: Obtains and Provides Hot Spring Business, Key Success Factors, Delphi Technique, Analytic Hierarchy Process 2. The Study of Releasing of Tea Tree Oil (Melaleuca alternifolia) from Alginate Microcapsules in Hot Spring Water The purpose of this part of study is to understand the releasing conditions for a tea essential oil (Melaleuca alternifolia) from microcapsule of Algenate-Melaleuca complex in hot spring water and its antibacterial effect. Hopefully, it could help to achieve sustainable operations for the hot spring business through the application of this microcapsule for sterilization of recycled hot spring water. Materials and methods of this study included drugs selection, experimental design, compounds for microcapsule preparation and drug releasing experimental design. The instruments included Fourier transform infrared spectrometer, confocal microscope, viscosity meter, UV-visible optical spectrometer and a bacteria counter, etc. The results indicated an antibacterial effect of microcapsules to the contaminated (recycled) hot spring water after adding sodium algenate-Melaleuca microcapsules. All bacteria in the test including Escherichia coli and Staphylococcus aureus were eliminated by this treatment. Algenate-Melaleuca microcapsules (containing 720 ppm of Melaleuca oil) with the size of 450 μm were made by our microfluid devices in various conditions. When the concentration for crosslinking agent was fixed, the longer reaction time caused a longer releasing for Melaleuca (10 min > 5 min > 1 min). However, with a fixed reaction time for crosslinking, the higher concentration of the crosslinking agent (1 M > 0.5 M > 0.1 M) caused a longer releasing of Melaleuca. Meanwhile, with the fixed concentration of the agent and the reaction time, the more active of the metal ions (Ca++＞Al++＞Zn++) caused a longer releasing time. However, in sodium algenate-Melaleuca microcapsules, the releasing amount of Melaleuca was independent to the concentrations of crosslinking agents as well as the species of the agents. No matter what concentrations, reaction times and the species of the crosslinking agents, they all had a coating rate of 96%. In conclusion, there was an antibacterial effect in the microcapsules-treated recycled hot spring water. Considering of the biocompatibility and crosslinking time, the releasing time of Algenate-Melaleuca microcapsules should be controlled at 3.3 hours with the optimized condition of 1 M CaCl2 with crosslinking time of l minute. Key words: Alginate-tea tree oil microcapsule, tea tree (Melaleuca alternifolia) essential oil, Antibacterial effect