Thermodynamic and exergoeconomic analysis of a novel CO2 based combined cooling, heating and power system

In this paper, a novel combined cooling, heating and power (CCHP) system consisting of a supercritical carbon dioxide (sCO(2)) power cycle, a transcritical carbon dioxide (tCO(2)) power cycle with a carbon dioxide based refrigeration cycle, and a direct heating (DH) system is proposed. In the novel system, the waste heat from sCO(2) power cycle is recovered by the tCO(2) power cycle to generate additional power and drive the CO2 based refrigeration cycle to provide cooling for users, and the DH system further recovers the waste heat from the sCO(2)/tCO(2) power cycle and the refrigeration compressor outflow to feed heat for users. Mathematical models are developed to conduct the thermodynamic and exergoeconomic analysis of the proposed CCHP system, and parametric studies on the effects of different key parameters on the system performance are carried out. Besides that, the optimization and comparative researches are performed to find out and compare the maximum system exergy efficiency and minimum total product unit cost for the proposed CCHP system and the stand-alone sCO(2) system. The results indicate that for different users' demands, the proposed CCHP system can obtain the best improvement by 12.01% for the system exergy efficiency and 5.14% for the total product unit cost, and the worst improvement by 10.83% for the system exergy efficiency and 4.12% for the total product unit cost, compared with the stand-alone sCO(2) power cycle. These results confirm the obvious superiority in thermodynamic and economic performance of the proposed CCHP system under different users' demands.