Investigation of an efficient and environmentally-friendly CCHP system based on CAES, ORC and compression-absorption refrigeration cycle: Energy and exergy analysis

Combined cooling heating and power (CCHP) is a promising energy supply technology which is widely installed in buildings due to its feasibility from techno-economic, performance and environmental points of view. In present paper, a novel cogeneration system based on compressed air energy storage (CAES), organic rankine cycle (ORC) and hybrid compression-absorption refrigeration cycle is proposed. The main objective of the proposed system is to improve the efficiency of the CAES system by providing cooling capacity from the rest of hot gases in turbine exhaust through employing an ORC driven refrigeration system. Also, the effect of the maximum to minimum pressure ratio of CAES vessel as a critical parameter on CAES volume and round trip efficiency (RTE) has been scrutinized. Using the environmentally-friendly compression-absorption refrigeration system, high temperature thermal energy storage (HTES) and R407C as the organic working fluid decrease fossil fuel consumption and make the proposed system fully environmentally-friendly. The results indicate that 2280 kW electrical energy and 416.7 kW cooling capacity are simultaneously generated during peak period. As a result, with 13.15% RTE enhancement in comparison to the individual CAES system, it reaches to 65.15% based on the proposed modification. Also, the results show that the overall exergy efficiency and total exergy destruction of the components are 49.17% and 1419 kW, in which the pressure regulating valve and the air turbine have the highest irreversibility and exergy destruction.