Document Type : Research Paper
1 Faculty of Aerospace, Malek Ashtar University of Technology, Iran, 15875-1774
2 Department of Mechanical Engineering, Azad University, West Tehran Branch, Iran, 1468763785
In this research, a combined cooling, heating and power system (CCHP) has been analyzed from the perspective of entropy and exergy. The primary driver and the cooling system for this combined system consist of a micro gas turbine and a hot water lithium bromide single-effect absorption chiller, respectively. The effects of compressor pressure ratio, micro turbine inlet gas temperature and chiller cooling capacity on important system efficiencies and other operational parameters (e.g., electrical efficiency, thermal efficiency, combined heating and power cogeneration efficiency, and combined cooling, heating and power cogeneration efficiency) have been investigated. The findings indicate that the system has its highest electrical efficiency at a compressor pressure ratio of 5. Also at this pressure ratio, the cogeneration efficiency (combined heating, cooling and power) and the exergy efficiency are about 48% and 24%, respectively. Moreover, the increase of the turbine inlet gas temperature has had a positive effect on the investigated parameters. The results show that the increase of cooling capacity reduces the cogeneration efficiencies, but has no effect on the exergy efficiency. Also, by considering specific values for the studied parameters, the amounts of generated entropy and destroyed exergy in various parts of the system have been calculated. The results indicate that the highest amounts of entropy and exergy have been generated and destroyed in the combustion chamber. Parts of the results indicate a system state in which the overall efficiency (combined heating, cooling and power cogeneration efficiency) of the system has increased 13% relative to the system’s initial state.
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