Comparative Analysis and Performance Optimization of a Geothermal Energy–Driven Absorption Combined Cooling and Power System

Abstract

The growing demand for low-carbon energy supply is driving intensified focus on developing geothermal energy utilization technology, which serves as a key low-grade heat source. In this context, absorption combined cooling, heating, and power (CCHP) systems have gained widespread attention as a promising technological approach. This paper proposes a double-effect absorption combined cooling and power system driven by geothermal energy. Simulations are conducted for the ammonia–water working pair and its alternative 1,3-dimethylimidazolium dimethyl phosphate/methanol [ mmim ] DMP / CH 3 OH , employing a combined thermodynamic and economic analysis method to evaluate system performance. Advanced exergy destruction analysis is performed to gain deeper insights into the internal processes, enabling a comprehensive assessment of the overall system performance. Furthermore, the influence of different variables on system performance is investigated, and multiobjective optimization is carried out. A comparison between ammonia–water and its alternative working fluid [ mmim ] DMP / CH 3 OH revealed that the ionic liquid solution achieves superior performance in the double-effect system. After multiobjective optimization, the optimal configuration yields a coefficient of performance (COP) of 1.04 and a unit product cost of $18.72/GJ for the [ mmim ] DMP / CH 3 OH system. Notably, this represents a 38.77% enhancement in COP compared with the conventional ammonia–water system. Based on the advanced exergy analysis, the avoidable endogenous exergy destruction of the system using [ mmim ] DMP / CH 3 OH working fluid accounts for 20.5%, which is lower than that of the ammonia–water system. This indicates a higher compatibility between the [ mmim ] DMP / CH 3 OH working fluid and the system configuration. These findings provide valuable insights for enhancing the utilization efficiency of renewable energy sources.