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Air compressor systems play a large role in modern industry. These compressors can account for a significant portion of a manufacturing facility’s electric consumption and any increase in efficiency can lead to economic benefits. Air compressors are sensitive to ambient conditions, as evidenced by the fact that compressing cooler and drier air decreases the amount of work required to compress the air. A thermodynamic model of an air compressor system was developed and several cases were run by using both vapor compression and absorption cycle chillers to cool and dehumidify the inlet air. The results show that the performance increases as much as 8 percent for the compressor system with absorption inlet cooling and as much as 5 percent when using vapor compression inlet cooling. Climates with higher humidity and temperatures can see the most benefits from inlet air cooling and dehumidification.

Falling film absorption process is studied for the simulation of the absorber of the absorption solar cooling system. In this study, we use different absorbents such as lithium chloride aqueous solution, and mixed solutions of lithium and calcium chloride aqueous solution, and water is the refrigerent. We also discuss the effects of various parameters of the absorbents such as the solution flow rate (the Reynolds number), the solution inlet temperature and the absorber vapor pressure. The results of the present study can provide the design reference for the absorption solar cooling systems.

This master’s thesis has been performed in Bangkok, Thailand at the company Eco Design Consultant Co., Ltd. The aim is to investigate the possibilities to generate absorption cooling from municipal solid waste in the Bangkok area. The investigation includes a comparison between waste incineration and biogas production with combustion to see which alternative is preferable. During the investigation, a Swedish perspective has been used. The research for the report mainly consisted of published scientific articles from acknowledged sources as well as information from different Thai authorities. Also, experts within different areas were contacted and interviewed. In order to determine which of the two techniques (waste incineration or biogas production with combustion) that is best suited to generate absorption cooling, a model was designed. This model involved several parameters regarding e.g. plant efficiency, amount of treated waste and internal heat usage. As for the results of the model, three parameters were calculated: the generated cooling, the net electricity generation and the reduced greenhouse emissions. The overall Thai municipal solid waste generation in Thailand is estimated to approximately 15 million tons per year and the majority of the waste ends up at open dumps or landfills. There are only two to three waste incinerators in the country and a few projects with biogas generation from municipal solid waste. The main electricity is today generated from natural gas which makes the majority of the Thai electricity production fossil fuel based. As for absorption cooling, two applications of this technique has been found in Thailand during the research; one at the Naresuan University and one at the Suvarnabhumi airport in Bangkok. The model resulted in that the best alternative to power absorption cooling technique is waste incineration. This alternative has potential to generate 3200 GWh cooling per year and 1100 GWh electricity per year. Also, this alternative resulted in the largest decrease of greenhouse gas emissions, ‐500 000 tons per year. The model also showed that the same amounts of generated cooling and electricity can never be achieved from biogas production with combustion compared to waste incineration. Regardless, waste incineration has an important drawback: the citizens of Thailand seem to oppose further development of waste incineration in the country. The biogas technique seems more approved in Thailand, which benefits this alternative. Due to the high moisture and organic content in the municipal solid waste, a combination between the two waste handling alternatives is suggested. This way, the most energy can be withdrawn from the waste and the volume of disposed waste is minimized. Our overall conclusion is that the absorption cooling technique has great potential in Thailand. There is an increasing power‐ and cooling demand, absorption cooling generated from either or both of the alternatives can satisfy these demands while reducing greenhouse gas emissions. We also believes that the cost for using absorption cooling has to be lower than for the current compression cooling if the new technique is to be implemented further.

<p>The energy consumption is continuous to increase around the world and with that follows the demand for sustainable solutions for future energy systems. With growing energy consumption from fossil based fuels the threat of global warming through release of CO₂ to the atmosphere increases. The demand for cooling is also growing which would result in an increased consumption of electricity if the cooling demand was to be fulfilled by electrically driven cooling technology. A more sustainable solution can be to use heat-driven absorption cooling where waste heat may be used as driving energy instead of electricity.</p><p>This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO₂ emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield.</p><p>The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO₂ emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO₂ emissions can be lowered to 45 CO₂/MWhc by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study.</p><p>Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand.</p>

Electricity-driven air-conditioning is energy-intensive and puts a strain to many grids during hot periods in warm climates. Solar thermal cooling could be an alternative to conventional cooling, using a renewable energy source and supplying the most energy during peak demand periods with insignificant effect to the electric grid. Office buildings in warm climates have high cooling loads, naturally peaking during daytime because of occupancy and ambient temperature. Thus, office buildings have a seemingly advantageous relationship between the possible supply of solar thermal energy and cooling demand. With this background, solar cooling systems for two office buildings with the same dimensions are investigated, placed in a tropical- and a sub-tropical location. There are great differences in the design conditions for solar cooling systems in the tropics and the sub-tropics, between the chosen locations Manila and Abu Dhabi more specifically. Manila has a quite evenly distributed cooling load while Abu Dhabi has a strongly pronounced summer season with very high maximum cooling loads, while the winter temperatures are relatively low. The prior described conditions creates a big difference between loads throughout the year, making a thermal chiller less effective in this aspect. However Abu Dhabi is expected to have an overall smoother- and ultimately a more high performance solar cooling system due to lower humidity, which facilitates the important cooling of the chiller. Evacuated tube collectors were used at both sites, where the collectors in Manila needs to be larger relative to the chiller cooling capacity, in order to compensate for the irregularity of direct solar radiation. The electricity price in Abu Dhabi is too low for the solar cooling system to be economically feasible compared to a conventional system, where the net values over 20 years are 163 000 € and 127 000 €, respectively. Manila has on its hand a very high price for electricity, making the 20-year net values for both the solar cooling- and the conventional system approximately 170 000 €.

The energy consumption is continuous to increase around the world and with that follows the demand for sustainable solutions for future energy systems. With growing energy consumption from fossil based fuels the threat of global warming through release of CO2 to the atmosphere increases. The demand for cooling is also growing which would result in an increased consumption of electricity if the cooling demand was to be fulfilled by electrically driven cooling technology. A more sustainable solution can be to use heat-driven absorption cooling where waste heat may be used as driving energy instead of electricity. This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO2 emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield. The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO2 emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO2 emissions can be lowered to 45 CO2/MWhc by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study. Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand. / QC 20101209

Syftet med detta examensarbete är att värdera och jämföra ett antal utvalda kyltekniker, med huvudfokus på värmedriven kyla. Dels för en specifik befintlig byggnad men även en generell jämförelse som kan ligga till grund för andra projekt. Arbetet är utförti samarbete med ÅF i Borlänge. Den specifika byggnaden som har undersökts är belägen i Borlänge och kyls idag av stadsvatten, och har en kyleffektpå 655kW. Borlänge Energis fjärrvärmenät ligger till grund för samtliga beräkningar och antaganden. Huvudsyftet har varit att jämföra de olika kylteknikerna ur ett ekonomiskt perspektiv, men även snudda vid ett miljöperspektiv. Utöver detta så var syftet att undersöka hur en fjärrvärmeleverantör ska kunna leverera kyla till sin kund, utan att behöva gräva ner nya fjärrkylledningar. De kyltekniker som jämförts i detta arbete är absorptionskyla, adsorptionskyla, sorptiv kyla &amp; eldriven kompressorkyla. För att kunna jämföra de olika teknikerna har den totala livscykelkostnaden beräknas. Investeringskostnader och data har erhållits ifrån leverantörer genom kontakt med kunniga säljare. Driftkostnader har beräknats fram med hjälp av driftdata samt energipriser hos Borlänge Energi. Kostnader för installation, frakt och lyft är inte medräknade i detta arbete. För den befintliga byggnaden visade det sig att den mest kostnadseffektiva lösningen är absorptionskyla, tätt följt av att komplettera befintligt system med frikyla i form utav en kylmedelkylare. Absorptionskylan har väldigt låga driftkostnader under sommarhalvåret, då fjärrvärmepriset är som lägst. Dyrast av teknikerna är adsorptionskyla, tack vare den dyra investeringskostnadenoch dess låga verkningsgrad. Även för den generella jämförelsen visade det sig att den mest kostnadseffektiva lösningen är absorptionskyla, tätt följt av eldriven kompressorkyla. Absorptionskylan har mycket låga driftkostnader, men kompressorkylan har istället en lägre investeringskostnad och mycket bättre verkningsgrad. Om Borlänge Energi skulle sälja fjärrvärmeproducerad kyla under sommaren, så skulle de vid 655kW kyleffekt ha en återbetalningstid avett absorptionskylaggregat på endast 2 år. Skulle de istället ha en kyleffekt på 100kW skulle återbetalningstiden vara ca 5 år. Slutsatser kan dras ifrån detta arbete att byggnader med högre kyleffekt är mer fördelaktiga för värmedriven kyla. / The aim of this thesis is to evaluate and compare a number of selected chilling techniques, with a main focus on heat driven cooling. Mainly for an existing building, but also a more general comparison that can be used as a basis for other projects. This thesis has been carried out in cooperationwith ÅF in Borlänge.The building that has been investigated is located in Borlänge. All calculations and assumptions regarding the district heating network are based on Borlänge Energi’s district heating network. The main purpose has been to compare the different cooling techniques from an economical point of view, but also a slight comparison from an environmental point of view. In addition, the purpose has been to investigate how a district heating supplier can deliver cooling to its customers without having to dig down newdistrict cooling pipes. The cooling techniques compared in this thesis are absorption chillers, adsorption chillers, sorptive cooling and conventional electrical compression chillers. In order to compare the different techniques, the total life cycle cost has been calculated. Investment costs and data have been obtained from skillful salesmen representing variouscompanies. Operating costs have been calculated using data and energy prices from Borlänge Energi. Costs for installation, shipping and lifting are not included in this thesis. The most cost-effective solution for the existing building is to install an absorption chiller, closely followed by complementing the existing cooling system with free cooling. The absorption chillers has very low operating costs during the summer, when the price of the district heating is at its lowest. The most expensive technique are adsorption cooling, due to its expensive investment cost and its low efficiency. For the general comparison, it was found that the most cost-effective solution is absorption chiller as well, closely followed by the conventional compressor chiller. The absorption chillers has much lower operating costs than its competitors, but the compressor chiller has a lower investment cost and a much better efficiency. If Borlänge Energi were to sell district heat-produced cooling during the summerusing an adsorption chiller, they would have a payback time of only approximately 2 years, with a cooling power of 655kW. With a cooling power of 100 kW, the payback time would be approximately 5 years. Conclusions can be drawn from this thesis that buildings with higher cooling demand are better suited for heat-driven cooling.

Orientador: Elaine Maria Cardoso / Resumo: Sistemas de refrigeração são indispensáveis para o modo de vida do homem atual, porém o grande gasto energético, de fontes não renováveis, e os impactos ambientais, levam-nos a estudar e a pensar em outras fontes de energia, de preferência renováveis, e em outros ciclos de refrigeração com gasto energético menor. Este trabalho tem como objetivo a modelagem de um sistema de refrigeração por absorção de vapor para o conforto térmico de ambientes, verificando a viabilidade desse sistema de refrigeração para aplicação em salas de aula. No presente trabalho mostra-se o sistema de refrigeração como sendo umas das alternativas ao sistema de refrigeração por compressão de vapor, o qual possui um alto gasto energético. Para o funcionamento do sistema de refrigeração por absorção de vapor foi proposto a energia solar como fonte de energia térmica do gerador, pois em regiões como Rio Verde – GO (localizada na região de latitude 17°47’S e longitude 50°58’W, onde o clima tropical predomina em quase todos os meses do ano, com temperatura mínima de ~20 ° C e máxima de ~30 °C) o condicionamento do ambiente é imprescindível. Foi utilizado o software EES para a simulação e modelagem do sistema de absorção de vapor, baseado nas trocas de calor entre os componentes desse sistema, desprezando perdas energéticas e de pressões que ocorrem em um ciclo real de absorção de vapor. As simulações e resultados mostraram que, nessa região tropical, o clima é propício para o uso de energia solar e que sua t... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Cooling systems are indispensable for today's man's way of life, but the high energy expenditure from non-renewable sources and environmental impacts lead us to study and think about other sources of energy, preferably renewable, and in other refrigeration cycles with lower energy expenditure. The objective of this work is the modeling of a vapor absorption refrigeration system for the thermal comfort of environments, verifying the viability of this refrigeration system for application in classrooms. In the present work is shown the refrigeration system as one of the alternatives to the system of refrigeration by compression of steam, which has high energy expenditure. For the operation of the vapor absorption refrigeration system, solar energy was proposed as the generator's thermal energy source, since in regions such as Rio Verde - GO (located in latitude 17° 47' S and longitude 50° 58' W, where the tropical climate prevails in almost every month of the year, with a minimum temperature of ~ 20° C and maximum of ~ 30° C), the ambient air-conditioning is essential. EES software was used for the simulation and modeling of the vapor absorption system based on the heat exchanges between the components of this system, disregarding energy and pressures losses that occur in a real vapor absorption cycle. The simulations and results showed that, in this tropical region, the climate is favorable to use solar energy and its transformation into thermal energy is sufficient for the ope... (Complete abstract click electronic access below) / Mestre