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This thesis deals with electricity, heat and cold production and describes ways of their simultaneous production – trigeneration. The main intention is to describe the ways of cooling the A1 building which is used by The Faculty of Mechanical Engineering. There is a Vapor compression cycle, a One stage absorption cycle and a Two stage compression cycle designed for cooling A1 building. This thesis includes suggestion for suitable commercial units for the purpose of cooling and a comparison of their running costs. An economic analysis is also included. Another part of the thesis is the design of a one stage absorption cycle connected to cogeneration units placed in The Faculty of Mechanical Engineering campus. The condenser of this cycle is also designed.

The thesis is focused on the cooling cycles, namely cycles of absorption. The work is divided into several parts, as problems to be solved. The first part deals with the principles and using refrigeration cycles in practice, their involvement and by comparing the working pairs of substances circulating in the absorption unit. The practical part deals with making a proposal for one-and two-level modular absorption cycle of 6 kW, and the subsequent techno-economic comparison with commonly supplied absorption unit

This diploma work aims to evaluate the functional connection of the cogeneration unit with an internal combustion engine and an absorption heat pump to increase the heating effect of the cogeneration. The aim of this work is to design a functional system and evaluate it from the technical - economic terms. In the introduction of the theoretical work the applied cogeneration technologies used in combined heat and power production are presented. Then there is described the principle of heat pumps, their basic components and theoretical comparison of compression and absorption heat pumps. In the practical part of this work is for a specific application in the area Technická 2 proposed merger of the cogeneration unit with an internal combustion engine and an absorption heat pump, while detailed design parameters used in absorption heat circulation are set. At the end of this paper there are designed various heat exchangers of applied absorption heat pump. The final part of the work is devoted to technical - economic assessment of applied design. In this assestment three different types of heat pumps are compared: Absorption heat pump with working solution H2O-LiBR, absorption heat pump with working fluids NH3-H2O and compressor heat pump.

Cette thèse vise à étudier la valorisation des rejets thermiques de basse température (inférieure à 100 °C) par les machines à absorption, dont principalement les transformateurs de chaleur à absorption (AHT) pour générer de la chaleur à une température plus élevée, et les cycles de réfrigération par absorption (ARC) pour la production de frigories. Les performances des machines à absorption sont exprimées suivant les températures et les COP qu’elles peuvent atteindre. Ces deux paramètres dépendent de l’architecture de la machine, des composants utilisés et de la paire de fluides réfrigérant-absorbant circulant dans la machine. L’objectif principal de ce travail est une nouvelle génération d’AHT qui puisse rendre utile la chaleur avec une différence de température par rapport à la source de chaleur disponible (rejet thermique) d’au moins 50°C. Pour l‘ARC, on cible une nouvelle génération de cycles capables de produire des frigories à une température inférieure à -20°C.Les résultats obtenus représentent une avancée majeure dans le domaine des cycles à absorption. En effet, les objectifs fixés de valorisation de chaleur basse température, jusqu’à 45°C, en rendant disponible de la chaleur haute température (supérieure à 120°C) et basse température (inférieure à -20°C) ont été atteints. Ceci représente une différence de température entre le rejet thermique et la chaleur utile de 75°C minimum. L’utilisation d’éjecteurs avec certains fluides de travail a permis le développement d'une nouvelle génération de cycles à absorption. / This thesis aims at studying the low temperature waste heat recovery (less than 100°C) by the use of absorption machines, mainly absorption heat transformers (AHT) to generate heat at a higher temperature, and absorption refrigeration cycles (ARC) to generate chilling power. The performances of absorption machines are expressed according to the temperatures and the COPs which they can reach. These two parameters depend on the cycle configuration, the components used and the refrigerant-absorbent pair of fluids circulating in the machine. The main objective of this work is a new generation of AHT which can produce heat with a difference in temperature compared to the available heat source (heat rejection) of at least 50°C. For the ARC, a new generation of cycles capable of producing chilling power at temperatures lower than -20°C is aimed.The results obtained represent a major progress in the absorption cycles field. The objectives set for this work of low temperature heat recovery, up to 45°C, by making available high temperature heat (above 120°C) and low temperature (below -20°C) have been achieved. This represents a minimal temperature difference between the waste heat and the useful heat of 75°C. The use of ejectors with specific working fluids allowed the development of a new generation of absorption cycles.

Several steps are followed in order to evaluate the cycle as the title suggests. The diffusion absorption refrigerator (DAR) cycle performance is evaluated when using helium or hydrogen as auxiliary gas. A slight increase in COP is found when using helium, but it is not sufficient to justify the cost. A secondary simulation of an alternate dual-pressure cycle using a pump is done as feasibility comparison with the same parameters as the diffusion cycle. It was found that the second cycle is not acceptable due to high evaporator temperatures needed to ensure liquid enters the pump instead of partially evaporated solution. This would greatly increase the work input required for what essentially becomes a compressor. Optimisation of the DAR is evaluated by simulating the use of a rectification column and the effects of different design points on overall performance. Meteorological data for Potchefstroom, South Africa is used to perform a yearly analysis on the simulated cycle and to specify a suitable design point. The use of a radiative cooling system as heat sink for the system is then investigated and incorporated into the system model. Finally, the performance characteristics of the simulated DAR cycle are discussed, verified and compared with available data from similar research. It is shown that a 40% solution aqua-ammonia-hydrogen cycle driven by 526 kW of solar thermal energy at 130°C and a system pressure of 1.5 MPa can easily achieve a COP over 0.4 with an air-cooled absorber at 40°C and a water-cooled condenser at 35°C. A 231 kW refrigeration capacity at an average evaporator temperature of –20°C is achieved, satisfying the requirements for a domestic refrigeration system. / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.

Several steps are followed in order to evaluate the cycle as the title suggests. The diffusion absorption refrigerator (DAR) cycle performance is evaluated when using helium or hydrogen as auxiliary gas. A slight increase in COP is found when using helium, but it is not sufficient to justify the cost. A secondary simulation of an alternate dual-pressure cycle using a pump is done as feasibility comparison with the same parameters as the diffusion cycle. It was found that the second cycle is not acceptable due to high evaporator temperatures needed to ensure liquid enters the pump instead of partially evaporated solution. This would greatly increase the work input required for what essentially becomes a compressor. Optimisation of the DAR is evaluated by simulating the use of a rectification column and the effects of different design points on overall performance. Meteorological data for Potchefstroom, South Africa is used to perform a yearly analysis on the simulated cycle and to specify a suitable design point. The use of a radiative cooling system as heat sink for the system is then investigated and incorporated into the system model. Finally, the performance characteristics of the simulated DAR cycle are discussed, verified and compared with available data from similar research. It is shown that a 40% solution aqua-ammonia-hydrogen cycle driven by 526 kW of solar thermal energy at 130°C and a system pressure of 1.5 MPa can easily achieve a COP over 0.4 with an air-cooled absorber at 40°C and a water-cooled condenser at 35°C. A 231 kW refrigeration capacity at an average evaporator temperature of –20°C is achieved, satisfying the requirements for a domestic refrigeration system. / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.

No panorama energético brasileiro, a geração de água quente e fria, pelos métodos convencionais, utilizando energia elétrica, implica em mais um fator de sobrecarga no sistema de geração, transporte e distribuição, potencializando os conhecidos picos de energia, onde o sistema de geração de energia elétrica de nosso país tem que estar dimensionado por apenas seis horas por dia e que para continuar garantindo esta energia exige pesados investimentos públicos, com grandes impactos. A energia elétrica é uma forma de energia de alta qualidade, devendo assim ser destinada a aplicações nobres, onde não é possível substituí-la. Maior importância tem sido dada ao estudo dos sistemas de refrigeração por absorção, devido às peculiaridades desses sistemas em relação aos ciclos por compressão e também pelo aproveitamento dos rejeitos térmicos. O objetivo desta pesquisa é contribuir para a redução do consumo de energia elétrica no setor comercial, mais especificadamente em hotelaria, situação esta que encontramos no consumo simultâneo de fonte de calor quente e fria. No entanto como fonte de energia alternativa a energia elétrica busca-se o gás LP, devido a sua capilaridade de distribuição de grande acesso aos empreendimentos em qualquer local do país e alto poder calorífico. O sistema de ar condicionado a gás LP é uma opção para sistemas de climatização. Proporciona uma significativa redução de consumo de energia quando se busca um equilíbrio nas demandas de fonte quente e fria / The Brazilian energy landscape, the generation of hot and cold water, by conventional methods, using electricity, implies an additional overhead factor in system generation, transmission and distribution, leveraging the familiar \"power surges\", where the system electric power generation in our country have to be sized for only six hours a day and to continue ensuring that energy demands heavy public investment, with major impacts. Electricity is a form of high quality power and should therefore be applicable for nobles, where you cannot replace it. Greater importance has been given to the study of the absorption refrigeration systems, due to the peculiarities of these systems in relation to the cycles of compression and also the utilization of waste heat. The objective of this research is to contribute to reducing electricity consumption in the commercial sector, more specifically in hotels, we found this situation in simultaneous consumption of heat source hot and cold. However as an alternative energy source to power up the search LPG, due to its capillary distribution of large enterprises access to anywhere in the country and high calorific value. The air conditioning system LPG is an option for air conditioning systems. Provides a significant reduction of energy consumption when it seeks to balance the demands of hot and cold source.

No panorama energético brasileiro, a geração de água quente e fria, pelos métodos convencionais, utilizando energia elétrica, implica em mais um fator de sobrecarga no sistema de geração, transporte e distribuição, potencializando os conhecidos picos de energia, onde o sistema de geração de energia elétrica de nosso país tem que estar dimensionado por apenas seis horas por dia e que para continuar garantindo esta energia exige pesados investimentos públicos, com grandes impactos. A energia elétrica é uma forma de energia de alta qualidade, devendo assim ser destinada a aplicações nobres, onde não é possível substituí-la. Maior importância tem sido dada ao estudo dos sistemas de refrigeração por absorção, devido às peculiaridades desses sistemas em relação aos ciclos por compressão e também pelo aproveitamento dos rejeitos térmicos. O objetivo desta pesquisa é contribuir para a redução do consumo de energia elétrica no setor comercial, mais especificadamente em hotelaria, situação esta que encontramos no consumo simultâneo de fonte de calor quente e fria. No entanto como fonte de energia alternativa a energia elétrica busca-se o gás LP, devido a sua capilaridade de distribuição de grande acesso aos empreendimentos em qualquer local do país e alto poder calorífico. O sistema de ar condicionado a gás LP é uma opção para sistemas de climatização. Proporciona uma significativa redução de consumo de energia quando se busca um equilíbrio nas demandas de fonte quente e fria / The Brazilian energy landscape, the generation of hot and cold water, by conventional methods, using electricity, implies an additional overhead factor in system generation, transmission and distribution, leveraging the familiar \"power surges\", where the system electric power generation in our country have to be sized for only six hours a day and to continue ensuring that energy demands heavy public investment, with major impacts. Electricity is a form of high quality power and should therefore be applicable for nobles, where you cannot replace it. Greater importance has been given to the study of the absorption refrigeration systems, due to the peculiarities of these systems in relation to the cycles of compression and also the utilization of waste heat. The objective of this research is to contribute to reducing electricity consumption in the commercial sector, more specifically in hotels, we found this situation in simultaneous consumption of heat source hot and cold. However as an alternative energy source to power up the search LPG, due to its capillary distribution of large enterprises access to anywhere in the country and high calorific value. The air conditioning system LPG is an option for air conditioning systems. Provides a significant reduction of energy consumption when it seeks to balance the demands of hot and cold source.