Selection of Working Fluid for Organic Rankine Cycle by Energy and Exergy, For Low Temperature Low Enthalpy Dholera Geothermal Reservoir

Abstract

In today’s scenario of increasing energy demand, it is high time to give emphasis on renewable energy sources. The conventional energy sources that humanity is depending upon today are not only depleting, but also cause significant environmental impact. The burning of coal and fossil fuels causes serious air pollution and several major cities are already under deep threat due to the increasing amount of pollution. Future predictions show an exponential amount of increase in energy demand. The fluctuating prices of fossil fuels also affect the global economy adversely. This situation gives importance to developing more renewable and clean energy resources that can be exploited economically. Renewable energy sources are natural resources, those that can be replenished by themselves as they are exploited. The major renewable resources are; solar energy, wind energy, geothermal energy, tidal energy, biomass, etc. Developing these resources can help to compact the ever increasing energy demand. The most important advantage is that the exploitation of these renewable resources causes little or no environmental impact. They are clean energy resources. Due to this, several countries are encouraging the exploration of renewable resources. If properly exploited, these resources can replace the conventional resources over a large scale. This will help humanity to compact with increasing environment pollution problems. In India there is a huge energy gap between the energy consumption and production. The production of crude oil in India is only one third of its consumption. The huge quantities of import of petroleum products cause a great hindrance for the economic growth of the country. The pollution problems of the country are at an alarming state. Considering this, government has tried to improve the exploitation of renewable resources. The paper describes selection of working fluid for an organic Rankine cycle to be used at low temperature, low enthalpy Dholera geothermal reservoir for electricity generation. It also describes energy, exergy, first law and second law analysis for selection of working fluids. Screening of appropriate working fluid is done for specific heat source working conditions. A simulation program has been developed in EES. The results have been calculated by changing evaporator temperature and pressure ratio and observing the effects on other parameters. A trade-off is done to select the working fluid among turbine outlet volume flow rate, volume flow ratio, net work output, first law efficiency, total irreversibility and second law efficiency of the system.