Energy and Exergy Analysis of a CCHP-ORC System Based on MGT - ORC and Absorption Chiller

摘要

A CCHP-ORC system consisting of a MGT, an ORC and an absorption refrigeration chiller was proposed in this study. A verified simulation model based on specific mass, energy conservation and exergy destruction was built. Thermodynamic analysis was applied to the system. A parametric study was carried out to investigate the impacts of the ORC's evaporating temperature and, turbine efficiency, and the ARC's generating temperature on the system's performance. Six different organic working fluids (R141b, Toluene, D4, n-Octane, n-Heptane and MM) were selected in this study, and their impact on the system s performance was also analyzed. The results showed that the CCHP-ORC system s primary energy efficiency and exergy efficiency could reach a maximum of 76.89% and 54.95% respectively, with toluene as the organic working fluid. The MGT accounted for a large part of exergy destruction in both the CCHP-ORC and reference system. Compared to the reference system, the total exergy destruction of the CCHP-ORC system decreased, for all six organic working fluids. The main exergy reduction occurred in the GEN, ABS and DHW. A T-Q diagram method was conducted to analyse the heat transfer process in the CCHP-ORC and reference system. The results showed that the CCHP-ORC system can significantly reduce the mean heat transfer temperature difference in the heat transfer process, which helps to decrease the exergy destruction in GEN, and improves the system's exergy efficiency. Hence, it is beneficial for the system s efficiency and exergy destruction to introduce ORC as a middle cycle into the CCHP system.