Volume 10: Sustainable Energy Solutions for Changing the World: Part II

Investigation on the coupling mechanism of serial Organic Rankine Cycle based on the utilization of hot dry rock Xueling Liu, Jintao Niu, Jiansheng Wang, Liwei Dong, Jianxiao Zhu

Abstract

In the utilization of hot dry rock, the temperature of hot dry rock production well will vary with running time. A thermodynamic model of serial Organic Rankine Cycle (ORC) is established in present work. According to specific selection criteria, six kinds of organic working mediums are selected for calculation. The parameters such as thermal efficiency, net output power, exergy efficiency and working medium flow are obtained. The results indicate that when dry hot rock injection well temperature is constant, dry hot rock production well temperature decreases with the increase of running time, which causes descend of thermal efficiency, net output power, exergy efficiency and working medium flow of serial ORC system. As value of k (ratio of temperature difference (inlet and outlet of heat source) in HT-stage ORC evaporator to temperature difference (inlet and outlet of heat source) in serial ORC system) rises, thermal efficiency, net output power, and exergy efficiency of serial ORC system firstly rise and then decrease, but working medium flow firstly descends and then rises. Maximum thermal efficiency, net output power, exergy efficiency and minimum working medium flow are obtained under the same k. By comparing the 6 selected organic working mediums, R600 presents the better thermodynamic performance.

Keywords Serial ORC, Variable temperature heat source, Coupling mechanism, Thermodynamic properties