Improvement research of condensing equipment in organic Rankine cycle power generation systems

Abstract

Dry hot rock power generation is an important part of geothermal energy application, and condenser has become an important part of the system because it can provide a lower outlet back pressure for steam turbine, and improve the power generation of the system. Engineering Equation Solver is applied to assess the performance of cooling towers for organic Rankine cycle power generation systems. In the present study, two models with different cooling towers are considered: In the first model, the predicted performance of the opening cooling tower for organic Rankine cycle systems is studied and compared with the experimental measurement for a 500 kW system. In the second model, because of the high mass flow of the cooling water and high energy consumption of the cooling water pump for the opening cooling tower, the predicted performance of the closed wet cooling tower to replace the opening cooling tower for organic Rankine cycle systems is studied. The models are capable of predicting the variation of evaporation and condensation temperatures, the pressure loss of heat exchangers. R123, R227ea, R245fa, R600 and R600a are tested as working fluids. The results show that the second model reduces the energy consumption of the cooling water pump, and it also improves the net power generation and net generation efficiency for using R227ea, R600, R600a. However, with the increase of the closed wet cooling tower pressure loss, both the net power generation and net generation efficiency decrease. Therefore, different working fluids are suitable for different pressure loss.