Modelling and Simulation of a Combined System Geothermal Binary Plant and Parabolic Solar Concentrator

Abstract

The present work describes a new prototype that uses the concentrated solar radiation to improve the performance of geothermal power plants. Current methods of heat recovering have been used to reduce the amount of fossil fuel used to produce vapor or to increase gas pressure and temperature, depending on the type of system; however, concentrated solar energy is an unknown resource that may help to increase vapor production at a relatively low cost. A conscientious review of the many geothermal power plants has shown that none of them is using a system like the one proposed in this paper, a clear sign of the novelty of the prototype. To this goal, a combined system, geothermal binary plant and parabolic solar concentrator, has been modelled and simulated for different evaporation and condensation temperatures. Parabolic solar concentrator has been used to increase water temperature. The simulation process covers a wide range of condensation temperature, from 80º C to 130º C, and a limited range for the evaporation temperature, between 160º C and 180º C. The simulation shows that the energy generation increases linearly with the temperature gap between evaporation and condensation, obtaining the best performance for an evaporation temperature of 175º C. The simulation has revealed that the new design provides extra power in close agreement with experimental tests. Prediction of power increase factor is 2.188. Net power represents, on average, the 88.5% of the generated power according to the simulation results. Power ratio of net to generated power is almost constant below a temperature gap threshold, but increases beyond this threshold following a second degree polynomial function which depends on the evaporation temperature.