Simulation on key influencing factors of CO2-ionic liquid mixture compression-absorption refrigeration cycle based on Aspen Plus

To explore the selection of cycle types and the effects of key parameters on the compression-absorption refrigeration system using the CO2-ionic liquid mixture, three typical cycle process models were established based on Aspen Plus. The effects of flow rate ratio of ionic liquid/CO2, high-low pressure ratio, and heat recovery efficiency were simulated and analyzed. The results indicated that the wet compression-absorption type had the highest refrigeration COP (3.13), which depended on its lowest total power consumption (521 W). However, it still faces the technical challenge of wet compression. The vapor compression cycle with solution circuit type had a slightly lower refrigeration capacity (low 149 W), but its refrigeration COP could be slightly higher than the desorber/absorber heat exchange type (high 0.09) under higher heat recovery efficiency (0.85). The increase of flow rate ratio could reduce the operating pressures but also reduce the refrigeration capacity, its excessive increase would lead to a decline in the refrigeration COP of three types. The increase of pressure ratio could improve the refrigeration capacity but also increase the total power consumption. Considering all factors, it was more appropriate to set at 3-3.5. The increase of heat recovery efficiency could improve the refrigeration capacity and COP.