A novel combined cooling and power cycle integrated ejector refrigeration and composition adjustment for stationary engine waste heat recovery

Abstract

The combined cooling and power cycle has wide applications ascribed to the feasibility of simultaneously providing cooling and electricity. The layout comprised of vapor compression refrigeration cycle and Organic Rankine Cycle by sharing condenser is one of the most common structures. However, for this kind of structure, the high temperatures of working fluid in compressor outlet and expander outlet aggravate the condensation load and lead to the decline of system performance. This study proposes a novel combined cooling and power cycle integrated of ejector refrigeration and composition adjustment running with CO2 mixture. Liquid separation condenser is introduced to realize composition adjustment. Working fluid with higher CO2 mass fraction flows to power sub-cycle and evaporation process of refrigeration sub-cycle. On the other hand, working fluid with smaller CO2 mass fraction is pumped to the inlet of ejector and heated by expansion exhaust. A stationary engine is chosen as the research objective. The co-generation system recovers waste heat of engine exhaust and coolant to provide cooling to refrigerating chamber. The results show the priority of the novel proposed co-generation system. Under the requirement of 0 ℃ chilled fluid, the basic combined cooling and power cycle could export 8 kW cooling capacity and 6.63 kW electricity, while the novel proposed system can export 4.5% more net power output with 8 kW cooling capacity output or export 18.6% higher cooling capacity with 6.63 kW electricity.