Investigation of the polygeneration system integrated with gas engine-driven heat pump system and CO2 Brayton cycle for waste heat recovery

•A polygeneration system with gas engine heat pump and CO2 Brayton cycle was proposed.•Cooling performances of gas engine-driven heat pump system were investigated.•The decreased degree of gas engine fuel with CO2 Brayton cycle was about 8.6%.•The increasing range of primary energy ratio with domestic hot water was above 43.5%.