Research on power generation system with Organic Rankine Cycle for hot dry rock resources in Xinghua area

Abstract Although China is rich in hot dry rock (HDR) resources, its application for the power generation process started late, and there is limited successful experience currently. To explore the power generation scheme for HDR resources in the Xinghua area, a power generation system with an organic Rankine cycle (ORC) with a re-heater is proposed, and the impacts of various key operating parameters on system performance are explored. Results show that the proposed ORC system can effectively use HDR resources for power generation, with the system thermoelectric conversion efficiency (TCE) reaching around 10%. The pressure drop of the cycling working medium (CWM) in each device leads to the lower net output power of the turbine and the overall TCE, and it should be reduced as much as possible. The increase in flow rate and temperature of geothermal fluid helps to provide more heat to the ORC system, thus increasing the net output power of the turbine and the system TCE. However, this also increases the condenser’s heat loss and geothermal fluid re-injection temperature, so they should be reasonably determined based on the actual demand. As for the CWM amount, its reasonable increase is conducive to absorbing more heat from the geothermal fluid and thus increases the net output power of the turbine. Nevertheless, the CWM steam temperature at the turbine inlet will be lower when the CWM amount is increased, which decreases the working capacity per unit mass of CWM steam and finally lowers the system TCE. This work explores the possible schemes of HDR power generation in the Xinghua area and can provide helpful guidance for practical HDR power generation in the future.