Exergy analysis and optimization of a combined cooling and power system driven by geothermal energy for ice-making and hydrogen production

Abstract

This paper investigates a combined cooling and power system driven by geothermal energy for ice-making and hydrogen production. The proposed system combines geothermal flash cycle, Kalina cycle, ammonia-water absorption refrigeration cycle and electrolyser. The geothermal energy can be efficiently converted to storable hydrogen and ice. Based on mathematical model, some key parameters are analyzed to figure out their effect on the exergetic performance. An exergy destruction analysis for all components has been performed to find out the distribution of exergy inefficiency. The system exergetic efficiency is optimized by Jaya algorithm and Genetic algorithm and the optimization results are compared. According to the parametric analysis, the exergy efficiency decreases as the back pressure of steam turbine and the back pressure of ammonia-water turbine increase. The exergy efficiency could increase first and then decline, as flash pressure, ammonia-water turbine inlet pressure and ammonia mass fraction of basic solution increase. The optimization results show that the exergy efficiency reaches 23.59%, 25.06% and 26.25% when the geothermal water temperature is 150 °C, 160 °C and 170 °C. Jaya algorithm has highly precise optimization results.