Energetic and exergetic analysis of a solar-assisted combined power and cooling (SCPC) system with two different cooling temperature levels

Distributed energy system has received increasing attention nowadays because of its great advantages on utilizing waste heat in cascade and renewable energy flexibly. This paper proposed a solar-assisted combined power and cooling system (SCPC) which supplies power and cooling capacity at two different temperature levels for a cold storage. The cogeneration system is composed of an internal combustion engine, evacuated tube collectors, a heat storage tank and an ammonia-water combined power and cooling system. The exhaust gas of the internal combustion engine is used to generate superheated ammonia-water vapor in the ammonia-water power generation subcycle. The jacket water waste heat is recovered and assisted by the solar collector field to drive the absorption-compression subcycle. Simulation work of the proposed system was conducted, and its performance was analyzed and evaluated from the aspects of energy and exergy. Thermal efficiency of the SCPC system is 70.35% with the renewable energy ratio of 18.1%, and its exergy efficiency is 45.52%. Combined with the coefficient of exergy destruction, average energy level difference was proposed and defined to analyze the energy saving mechanism and further improvement potential of the proposed system. The effects of key parameters including turbine inlet pressure and generation pressure in low-pressure reboiler at different condensation/absorption temperatures have been investigated, providing guidance for the system's optimal design.