Advanced power-refrigeration-cycle integrated WHR system for marine natural gas engine base on multi-objective optimization

Abstract

In the face of huge global energy consumption today, technological implementation of waste heat recovery for electrical generating and refrigeration is of crucial significance for energy conservation. The high-temperature exhaust from marine natural gas engines carries a substantial quantity of thermal energy, making it an attractive option for waste heat recovery. A unique cycle system involving a supercritical CO2 cycle subsystem, a trans-critical CO2 Rankine cycle subsystem, and a double effect absorption refrigeration cycle is developed to utilize the waste energy in the maritime natural gas engine. The parameter variation pattern of each subsystem is investigated, and a total of eight organic working fluids with varying fractions are introduced into the trans-critical CO2 system for further investigation. The thermal-economic outcomes of the suggested integrated system are maximized by implementing the multi-objective optimization process, and it is found that when R32 with a mass fraction of 0.6138 is used as an additive in the trans-critical CO2 system, it has the highest net output power (311.6 kW) and lowest LCOE (0.0298 $/kWh). The results indicate that the novel design is a viable and meaningful strategy for marine natural gas engines' waste heat recovery.