Study of a Supercritical CO2 Power Cycle Application

Cogeneration, or combined heat and power (CHP), is the use of a heat engine or power station to simultaneously generate electricity and useful heat. Cogeneration is considered as a thermodynamically efficient use of fuel [1]. In separate productions of electricity, some energy must be discarded as waste heat, but in cogeneration this thermal energy is put to use. Usually the CHP plant uses steam as the working fluid and has a flexible ratio of cogeneration, which depends on the season. In turn, supercritical CO2 (S-CO2) power cycles are proposed for future energy applications because of their high thermal efficiency [2]. However, the possibilities of carbon dioxide applications as working fluids for cogeneration power plants have never been published or expanded on. This paper considers several S-CO2 cycles in terms of application in a CHP plant. Combined steam/S-CO2 cycles are also proposed and described, though the S-CO2 cycles are used as “bottom ” cycles which only turn on when heat production is not required. The performance of several standalone cycles and combined steam/S-CO2 cycles are compared with typical steam cogeneration cycle performances. Combined steam/S-CO2 cycles, steam turbine and S-CO2 turbine features are considered