Dynamic analysis and operation simulation for a combined cooling heating and power system driven by geothermal energy

Abstract

The geothermal energy is a renewable energy resource, which is viewed as a promising alternative to fossil energy. Powered by geothermal energy, the combined cooling heating and power (CCHP) system can potentially become an option for efficient energy supply. However, the operation of the CCHP system is subject to energy demand and temperature degradation of geothermal water. To capture the dynamic characteristics and off-design performance of CCHP system under different working conditions, the dynamic mathematical models of a CCHP system is established and a control strategy is proposed. On this basis, the effect of heating/cooling load on the dynamic behavior of the CCHP system is analyzed and the effect of temperature degradation of geothermal water on the off-design performance is investigated. The results indicate that the lower heating/cooling load leads to greater overshoot and longer settling time in the dynamic process. The settling time of Cooling-Power mode is much longer than that of Heating-Power mode. As the temperature of geothermal water decreases from 120 °C to 108 °C, the heating capacity of the CCHP system decreases by 28.87% and the cooling capacity decreases by 14.72%.In addition, the operation simulation shows that the CCHP system can precisely track hourly heating and cooling load of the student dorm building.