Arbetet baseras på en kylanläggning som installerats på ett biogas företag, som till en början var tänkt som ett pilotprojekt men som nu används fullt ut i anläggningen. Projektet var inte utvärderat eller dokumenterat och vilken effekt som överförs var obekant. Arbetets innebörd var att beräkna effekten samt dokumentera systemet i form av både beräkningar, ritning och eventuella effektiviserings områden. Beräkning gjordes via entalpi skillnaden som togs ut över involverade värmeväxlare, samt flödet som togs ut via en reglerventil med hjälp av ett mätinstrument. Ritning gjordes via programmet Visio utifrån anläggningens nuvarande konstruktion. Resultatet för kyleffekten som överfördes beräknades fram via flöde och entalpi, med resultatet 14,03kW över båda värmeväxlarna. Även beräkning på vad en potentiell förbättring av isolering i rörsystemet skulle kunna bidra med där utifrån beräkningarna skulle energibesparingen kunna fördubblas gentemot nuvarande. / The work is based on a cooling plant installed at a biogas company, which was initially intended as a pilot project but is now fully used in the plant. It is not evaluated or documented and how much power is transmitted is unknown. The meaning of the work is to find out the effect and document the system in the form of both calculations, drawing and any areas of efficiency. Calculation was made via enthalpy the difference that was taken out over the heat exchangers involved, as well as the flow that was taken out via a control valve with the help of a measuring instrument. Drawing was made via the Visio program based on the facility's current design. The result for the cooling power that was transferred was calculated via flow and enthalpy, where the result was 14.03 kW over both heat exchangers. Calculation of what a potential improvement of insulation of the pipe system could contribute, based on the calculations, the energy savings could be doubled compared to the current one.

Fuel consumption reduction is one of the main challenges in the automotiveindustry due to its economical and environmental impacts as well as legalregulations. While fuel consumption reduction is important for all vehicles,it has larger benefits for commercial ones due to their long operational timesand much higher fuel consumption. Optimal control of multiple energy buffers within the vehicle proves aneffective approach for reducing energy consumption. Energy is temporarilystored in a buffer when its cost is small and released when it is relativelyexpensive. An example of an energy buffer is the vehicle body. Before goingup a hill, the vehicle can accelerate to increase its kinetic energy, which canthen be consumed on the uphill stretch to reduce the engine load. The simplestrategy proves effective for reducing fuel consumption. The thesis generalizes the energy buffer concept to various vehicular componentswith distinct physical disciplines so that they share the same modelstructure reflecting energy flow. The thesis furthermore improves widely appliedcontrol methods and apply them to new applications. The contribution of the thesis can be summarized as follows: • Developing a new function to make the equivalent consumption minimizationstrategy (ECMS) controller (which is one of the well-knownoptimal energy management methods in hybrid electric vehicles (HEVs))more robust. • Developing an integrated controller to optimize torque split and gearnumber simultaneously for both reducing fuel consumption and improvingdrivability of HEVs. • Developing a one-step prediction control method for improving the gearchanging decision. • Studying the potential fuel efficiency improvement of using electromechanicalbrake (EMB) on a hybrid electric city bus. • Evaluating the potential improvement of fuel economy of the electricallyactuated engine cooling system through the off-line global optimizationmethod. • Developing a linear time variant model predictive controller (LTV-MPC)for the real-time control of the electric engine cooling system of heavytrucks and implementing it on a real truck. / <p>QC 20160128</p>

Reliable, efficient and cost-effective energy supply is crucial for economic and social development. Mining and industrial sectors consumed close to 37% of the total energy produced in the world during 2013. The South African power network is strained by the rapid expansion of mining, industrial and public sectors. Generation, transmission and distribution of electrical energy are in progress, but supply will not meet demand in the near future. The South African electricity supplier needs capital for expansion. Electricity price increases have been significantly higher than increases in the gold price over the last few years. Mining companies are under pressure from government to improve their labour relations. They are obligated to spend money on local infrastructure development. Therefore, cost efficiency receives higher priority than ever before and requires an implementation strategy. Cooling systems on mines proved to be significant electricity consumers. These systems lack integrated management and efficient and optimised control. Electricity demand can be reduced through implementation of energy saving measures on these cooling systems. Energy saving measures reduce the operational costs of mining to ensure that mines stay globally competitive. The identification of long-term challenges for energy saving measures is crucial. Successful implementation of energy saving measures results in improved utilisation and performance of mine cooling systems. These measures must be maintained to ensure a constant positive impact on reduced electrical energy consumption. The electrical energy savings are dependent on external factors, such as ambient conditions. Improved implementation strategies of energy saving measures will prevent deterioration of utilisation and performance of the mine cooling systems. Monitoring and reporting of key performance indicators are crucial. Lack of integrated maintenance can lead to lost opportunities and the deterioration of equipment and machines. The improved implementation strategies in two separate case studies proved sustainable savings of 1.73 MW and 0.66 MW respectively. The electricity cost savings for Mine A and Mine B are R8.8 million and R2.9 million respectively. These savings have been sustained for periods of seventeen and seven months respectively, indicating the value of the study. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Reliable, efficient and cost-effective energy supply is crucial for economic and social development. Mining and industrial sectors consumed close to 37% of the total energy produced in the world during 2013. The South African power network is strained by the rapid expansion of mining, industrial and public sectors. Generation, transmission and distribution of electrical energy are in progress, but supply will not meet demand in the near future. The South African electricity supplier needs capital for expansion. Electricity price increases have been significantly higher than increases in the gold price over the last few years. Mining companies are under pressure from government to improve their labour relations. They are obligated to spend money on local infrastructure development. Therefore, cost efficiency receives higher priority than ever before and requires an implementation strategy. Cooling systems on mines proved to be significant electricity consumers. These systems lack integrated management and efficient and optimised control. Electricity demand can be reduced through implementation of energy saving measures on these cooling systems. Energy saving measures reduce the operational costs of mining to ensure that mines stay globally competitive. The identification of long-term challenges for energy saving measures is crucial. Successful implementation of energy saving measures results in improved utilisation and performance of mine cooling systems. These measures must be maintained to ensure a constant positive impact on reduced electrical energy consumption. The electrical energy savings are dependent on external factors, such as ambient conditions. Improved implementation strategies of energy saving measures will prevent deterioration of utilisation and performance of the mine cooling systems. Monitoring and reporting of key performance indicators are crucial. Lack of integrated maintenance can lead to lost opportunities and the deterioration of equipment and machines. The improved implementation strategies in two separate case studies proved sustainable savings of 1.73 MW and 0.66 MW respectively. The electricity cost savings for Mine A and Mine B are R8.8 million and R2.9 million respectively. These savings have been sustained for periods of seventeen and seven months respectively, indicating the value of the study. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Thesis (MScEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008. / This study evaluates the performance characteristics of a power plant incorporating a steam turbine and a direct air-cooled dry/wet condenser operating at different ambient temperatures. The proposed cooling system uses existing A-frame air-cooled condenser (ACC) technology and through the introduction of a hybrid (dry/wet) dephiegmator achieves measurable enhancement in cooling performance when temperatures are high. In order to determine the thermal-flow performance characteristics of the wet section of the dephlegmator, tests are conducted on an evaporative cooler. From the experimental results, correlations for the water film heat transfer coefficient, air-water mass transfer coefficient and the air-side pressure drop over a deluged tube bundle are developed. During periods of high ambient temperatures the hybrid (dry/wet) condenser operating in a wet mode can achieve the same increased turbine performance as an oversized air-cooled condenser or an air-cooled condenser rith adiabatic cooling (spray cooling) of the inlet air at a considerably lower cost. For the same turbine power output the water consumed by an air-cooled condenser incorporating a hybrid (dry/wet) dephlegmator is at least 20% less than an air- cooled condenser with adiabatic cooling of the inlet air. / Sponsored by the Centre for Renewable and Sustainable Energy Studies, Stellenbosch University

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Steven J. Eckels / The research presents the investigation of personal cooling systems (PCS) and their effects on humans from a thermodynamic perspective. The original focus of this study was to determine the most appropriate PCS for dismounted U.S. Army soldiers in a desert environment. Soldiers were experiencing heat stress due to a combination of interrelated factors including: environmental variables, activity levels, and clothing/personal protective equipment (PPE), which contributed to the buildup of thermal energy in the body, resulting in heat stress. This is also a common problem in industry, recreation, and sports. A PCS can serve as a technological solution to mitigate the effects of heat stress when other solutions are not possible. Viable PCS were selected from the KSU PCS database, expanded to over 300 PCS in the course of this study. A cooling effectiveness score was developed incorporating the logistical burdens of a PCS. Fourteen different PCS configurations were tested according to ASTM F2370 on a sweating thermal manikin. Four top systems were chosen for ASTM F2300 human subject testing on 22 male and 2 female soldiers in simulated desert conditions: dry air temperature = 42.2 ºC, mean radiant temperature = 54.4 ºC, air velocity = 2.0 m/s, relative humidity = 20%. Subjects wore military body armor, helmets and battle dress uniforms walking on treadmills at a metabolic rate of approximately 375-400W. All the PCS conditions showed significant reductions in core temperature rise, heart rate, and total sweat produced compared to the baseline (p<0.05). The expected mean body temperature was higher in the human subjects than expected based on the cooling obtained from the sweating manikin test. Lowered sweat production was determined to be the likely cause, reducing the body’s natural heat dissipation. The ASHRAE two-node model and TAITherm commercial human thermal models were used to investigate this theory. A method to account for fabric saturation from dripping sweat was developed and is presented as part of a new model. This study highlights that the response of the human body is highly complex in high-activity, high-temperature environments. The modeling efforts show the PCS moved the body from uncompensable to compensable heat stress and the body also reduced sweating rates when the PCS was used. Most models assume constant sweating (or natural heat loss) thus the PCS sweat reduction is the likely cause of the higher than expected core temperatures, and is an important aspect when determining the purpose of a PCS.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: A passive night-sky radiation cooling system consists of a radiation panel and a cold water storage tank. The stored cold water may be used to cool a room during the day time, particularly in summer. In this thesis a theoretical and mathematically sound simulation model is developed. An experimental set-up was constructed and subsequently used to show that the theoretical model effectively simulates the transient heating or cooling response of the system. It is shown that under South African conditions the typical heat emitting rate during the night is 55 W/m2. After the heat has been removed from the water, it is stored in a cold water tank from where it is circulated through a natural convector during the day time to absorb heat from the room. The experiment extracted a minimum of 102 W/m3 of heat from a 1.87 m3 galvanized steel room while a brick room with a volume of 120 m3 requires 22.7 W/m3. Additional to cooling, the system during the day, absorbed an average of 362 W of energy and heated 68 l of water from 24 °C to 62 °C within an 8-hour period. The system achieved similar results during winter conditions and the experiment confirms that the system is capable of operating without a control system. Therefore it is recommended that renewable energy-conscious designers pay more attention to the use of night-sky radiation cooling in future. / AFRIKKANSE OPSOMMING: en ’n koue water tenk. Die sisteem kan gebruik word om ’n vertrek gedurende die dag te verkoel, veral in die somer, deur gebruik te maak van die gestoorde verkoelde water. In hierdie tesis word ’n teoretiese en sinvolle wiskundige simulasie model ontwikkel. ’n Eksperimentele stelsel is gebou en vervolgens gebruik om te bewys dat die teoretiese model die veranderende verkoeling en verwarming van die stelsel effektief simuleer. Die tesis dui aan dat onder Suid Afrikaanse toestande daar ’n hitte vrystellings tempo van 55 W/m2 is gedurende die nag. Nadat die water verkoel is, word dit gestoor in die koue water tenk vanwaar dit deur ’n natuurlike konvektor sirkuleer en gedurende die dag warmte vanuit die vertrek onttrek. Die eksperiment het ’n minimum van 102 W/m3 warmte vanuit die galvaniseerde 1.87 m3 vertrek geabsorbeer, terwyl ’n baksteen vertrek van 120 m3, 22.7 W/m3 verkoeling benodig. Bykomstig tot die verkoelingstelsel verhit die sisteem 68 l water vanaf 24 °C to 62 °C gedurende ’n 8-uur periode in die dag, dus word 362Wenergie geabsorbeer. Die sisteem is ook getoets tydens winter toestande, die resultate was dieselfde as wat in die somer verkry is. Verder is daar ook bewys dat die sisteem sonder enige beheerstelsel kan funksioneer. Verder word daar aanbeveel dat hernubare energie bewuste ontwerpers in die toekoms meer aandag aan ruimte straling verkoeling skenk.

In the process of engine design, it is important for the engine designer to predict the accurate component temperatures. Controlling the temperature of engine components requires a better understanding of the coolant behaviour in the coolant jacket of an engine which is critical to internal combustion engine design, The studies reported in the literature emphasize the influence of the cooling system on other engine operation such as exhaust emission, fuel consumption and engine wear. In this context, much work has been done with the purpose of improving the coolant jacket design and components of the cooling system to achieve higher performance. (Some of these studies) Previous researches have shown the possibility of achieving higher engine efficiency and performance with higher coolant temperature. This project aims at understanding the coolant flow behaviour in the coolant jackets of a diesel engine and investigating the possibility of running the engine at higher coolant temperatures by predicting the temperature distribution of the structure which is required for the assessment of the durability ofthe engine components. In this thesis, CFD (Computational Fluid Dynamics) and FE (Finite Element) techniques are used to study coolant flow in the coolant jackets and to predict the temperature distribution within the engine structure respectively. The objectives are to develop an FE model of the engine structure for thermal analyses and a CFD model of the fluid domain for the coolant flow CFD analyses. A number of case studies are carried out with the purpose of determining the most suitable technique for accurate temperature prediction. The methodology of manual coupling approach between CFD and FE analyses, which is more widely used in industry, and conjugate approach are demonstrated. Using these approaches, thermal analysis of the engine is conducted with the purpose of identifying the thermally critical locations throughout the engine. Furthermore, the influences of higher coolant temperature on these thermally critical regions of the engine are highlighted by carrying out four case studies with coolant inlet temperatures of 110°C, !ISOC, 117.5"C and !20°C. The temperature rise at the particular points around thermally critical regions is found to be in the range of 3-9 degrees at the higher coolant temperatures. This slight increase in temperature of critical locations may affect the durability of the structure. However, without carrying out the structural analyses it is not possible to comment on the durability of the engine structure. The effects of surface roughness and viscosity on heat transfer rate are also investigated and shown to be insignificant.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Steven J. Eckels / The research presents the investigation of personal cooling systems (PCS) and their effects on humans from a thermodynamic perspective. The original focus of this study was to determine the most appropriate PCS for dismounted U.S. Army soldiers in a desert environment. Soldiers were experiencing heat stress due to a combination of interrelated factors including: environmental variables, activity levels, and clothing/personal protective equipment (PPE), which contributed to the buildup of thermal energy in the body, resulting in heat stress. This is also a common problem in industry, recreation, and sports. A PCS can serve as a technological solution to mitigate the effects of heat stress when other solutions are not possible. Viable PCS were selected from the KSU PCS database, expanded to over 300 PCS in the course of this study. A cooling effectiveness score was developed incorporating the logistical burdens of a PCS. Fourteen different PCS configurations were tested according to ASTM F2370 on a sweating thermal manikin. Four top systems were chosen for ASTM F2300 human subject testing on 22 male and 2 female soldiers in simulated desert conditions: dry air temperature = 42.2 ºC, mean radiant temperature = 54.4 ºC, air velocity = 2.0 m/s, relative humidity = 20%. Subjects wore military body armor, helmets and battle dress uniforms walking on treadmills at a metabolic rate of approximately 375-400W. All the PCS conditions showed significant reductions in core temperature rise, heart rate, and total sweat produced compared to the baseline (p<0.05). The expected mean body temperature was higher in the human subjects than expected based on the cooling obtained from the sweating manikin test. Lowered sweat production was determined to be the likely cause, reducing the body’s natural heat dissipation. The ASHRAE two-node model and TAITherm commercial human thermal models were used to investigate this theory. A method to account for fabric saturation from dripping sweat was developed and is presented as part of a new model. This study highlights that the response of the human body is highly complex in high-activity, high-temperature environments. The modeling efforts show the PCS moved the body from uncompensable to compensable heat stress and the body also reduced sweating rates when the PCS was used. Most models assume constant sweating (or natural heat loss) thus the PCS sweat reduction is the likely cause of the higher than expected core temperatures, and is an important aspect when determining the purpose of a PCS.

O estudo teve como objetivo avaliar as respostas hormonais, fisiológicas e comportamentais de vacas Holandesas frente a situações de conforto ou estresse térmico ambiental. O experimento desenvolvido entre os verões de 2007 e 2008 no Campus Administrativo da Universidade de São Paulo (USP), Pirassununga, SP, utilizou 28 fêmeas de 1ª a 3ª lactações com produção média de 20 kg/dia divididas em dois grupos experimentais após a parição, com e sem disponibilidade de climatização em galpão do tipo free-stall. Os parâmetros ambientais foram avaliados através do cálculo do índice de temperatura e umidade (ITU). As colheitas de dados fisiológicos (temperatura retal, temperatura de superfície corporal do dorso e base da cauda, frequência respiratória), hormonais (cortisol e IGF-I), comportamentais e de produção e qualidade do leite foram realizadas em cinco condições climáticas no ano (outono, inverno, primavera, verão seco e verão chuvoso) caracterizadas pela temperatura, umidade relativa e radiação solar. No verão os animais foram submetidos ao Teste de Capacidade Termolítica (CT) e a um estudo comparativo de um período de sete dias sob estresse calórico em câmara climática e desafio com aplicação de ACTH. No experimento 1 o teste de capacidade termolítica foi validado. A CT foi igual para animais em lactação ou secos (P>0,05), e maior para vacas mantidas sob sistema de climatização ao longo do ano (P<0,01). Houve influência da exposição ao sol sobre todas as variáveis fisiológicas (P<0,01). Os níveis plasmáticos de cortisol foram maiores antes da exposição ao sol e depois do repouso por 1 hora à sombra para vacas em lactação (P=0,03) e para as sem disponibilidade de climatização (P=0,03). O IGF-I foi maior nas vacas secas em final de gestação (P<0,01). No experimento 2 a temperatura retal não teve influência da climatização, com os dois grupos apresentando valores abaixo de 38,56 ºC ao longo do ano (P=0,11). Observou-se uma tendência de alta (P<0,01) nas concentrações plasmáticas de cortisol entre outono e inverno, começando o decréscimo até o início do verão seco e um novo aumento durante o verão chuvoso, e um comportamento inverso para o IGF-I. Temperatura retal mostrou uma correlação moderada e positiva (P<0,01) com a temperatura superficial (0,46) e frequência respiratória (0,35). A temperatura do ar e ITU apresentaram correlações positivas de moderada à alta com as temperaturas retal, da base da cauda e superficial, e também com a frequência respiratória (P<0,01). No experimento 3 as vacas passaram a maior parte do dia na sombra em pé (84,2 %) independente da estação do ano. O ambiente climatizado proporcionou maior frequência de alimentação e produção de leite durante o verão (P<0,05), assim como teor de gordura 17,9 % maior (P<0,01). No experimento 4 os animais foram submetidos ao estresse pontual causado pelo uso do ACTH e ao estresse calórico prolongado em câmara climática. Tanto a administração de ACTH quanto a exposição ao calor prolongado em câmara climática aumentaram os níveis de cortisol plasmático. Durante o estresse calórico houve diminuição do IGF-I e produção leiteira e aumento das variáveis fisiológicas ligadas a termorregulação. / The study aimed to evaluate the hormonal, physiological and behavioral responses of Holstein cows in situations of a comfort or heat environment. The experiment was conducted between the summers of 2007 and 2008 in the University of São Paulo (USP), Pirassununga, SP, and used 28 females from 1st to 3rd lactations with average production of 20 kg/day divided into two experimental groups after birth, with and without an evaporative cooling system in a free-stall. Environmental parameters were evaluated by temperature and humidity index (THI). Collection of physiological data (rectal temperature, body surface, internal base of tail, respiratory rate), hormonal (cortisol and IGF-I), behavioral and production and milk quality were conducted in five climatic conditions (autumn, winter, spring, dry summer and rainy summer) characterized by air temperature, relative humidity and solar radiation. In summer the animals were subjected to Thermolysis Capacity Test (CT) and a comparative study of a period of seven days under heat stress in climatic chamber and challenged with ACTH administration. In experiment 1 the Thermolysis Capacity Test was validated. The CT was the same for dry or lactating animals (P>0.05) and higher for cows kept in evaporative cooling system throughout the year (P<0.01). The results showed influence of sun exposure on all physiological variables (P<0.01). Plasma levels of cortisol were higher before sun exposure and after the one hour rest under shade for lactating cows (P=0.03) and for no cooled animals (P=0.03). IGF-I was higher in dry cows in late gestation (P<0.01). In experiment 2 the evaporative cooling system did not show influence on rectal temperature, with both groups having values below 38.56 ºC throughout the year (P=0.11). It was observed an upward trend (P<0.01) in plasma cortisol concentrations between autumn and winter, starting the decline until the beginning of dry summer and a further increase during rainy summer, and an opposite pattern for IGF- I. Rectal temperature showed a moderate and positive correlation (P<0.01) with the body surface temperature (0.46) and respiratory rate (0.35). The air temperature and THI showed moderate to high positive correlations with rectal temperatures, and the internal base of tail, and also with the respiratory rate (P<0.01). In experiment 3 cows spent most of the day standing in the shade (84.2%) regardless of season. Cooled cows had a higher feeding frequency and milk production during summer (P<0.05) and fat content 17.9% higher (P<0.01). In experiment 4, cows were subjected to the short stress caused by the ACTH administration and prolonged heat stress in climatic chamber. Both the administration of ACTH as prolonged exposure to heat in climatic chamber increased the levels of plasma cortisol. During heat stress a decrease in plasma IGF-I and milk production was observed, and an increase in physiological variables related to thermoregulation.