In this work, a thermodynamic analysis consisting of energy and exergy analyses is carried out to determine the performance of a single flash geothermal power plant. A new derivation for determination of the optimum separator temperature, which results in maximum turbine power output, is achieved. The energy and exergy analyses are carried out at that optimum separator temperature. The thermodynamic derivation showed that the separator would result in maximum performance of the power plant when it operates at the average value of the production well and condenser temperatures. Moreover, the derivation was numerically validated by calculating three different values for the geothermal well temperatures. The results show that the highest exergy destruction rate is in the expansion valve followed by the steam turbine, the mixing process and the pump. The separator has exactly zero exergy destruction rate while the condenser has almost zero exergy destruction rate. The results also show that the exergy destruction rate for all components of the power plant decreases with reduction in the geofluid temperature of the production well except for the condenser. The maximum energy efficiency of the power plant is about 12.5, 11 and 9.5% when the geofluid of the geothermal well temperature is 300, 275 and 250°C, respectively.
A renewable energy source, especially solar energy, is one of the best alternatives for power generation in rural areas. Organic Rankine cycle (ORC) can be powered by a low-grade energy source, suitable for small-scale power production in rural areas. This study investigates the combined power generation and cooling system using the combination of ORC and vapor compression cycle (VCC), where ORC is powered by a parabolic trough solar collector. Thermodynamic and economic simulation of the system is conducted for four different working fluids, which are R245fa, R114, R600 and R142b. It can be concluded that the thermal efficiency of the power plant increases by using the combined ORC-VCC system. The effect of thermodynamic parameters such as turbine inlet temperature and pressure on the system performance is also discussed, and the optimal design values are provided. The results show that the power plant uses R245fa as the minimum exergy destruction rate. The study indicates that R114 gives minimum cost function (PCEU) for 137°C turbine inlet temperature while the minimum PCEU for R142b is obtained at a turbine inlet pressure of 2500 kPa. Finally, the study indicates that the inlet pressure of the turbine has a significant impact on the system cost and thermal efficiency.
The need for energy is increasing worldwide as the population has a continuous trend of increase. The restrictions on energy sources are becoming tougher as the authorities set these developed and developing countries. This leads to looking for other alternative energy sources to replace the conventional energy sources, leading to greenhouse emissions. Environmentally friendly energy sources (renewable energies), for example, geothermal, solar and wind, are viewed as clean and sustainable energy sources. Among these kinds of energy sources, geothermal energy is one of the best options because, like solar and wind energy sources, it does not depend on weather conditions. In this work, a single flash geothermal power plant is used to power a transcritical CO2 power plant is proposed. The energy and exergy analysis of the proposed combined power plant has been performed and the best possible operating mode of the power plant has been discussed. The effects of parameters such as separator pressure, CO2 condenser temperature and CO2 turbine inlet pressure and the pinch point on the energy efficiency, exergy efficiency and output power are determined and discussed. Our results indicate that the highest exergy destruction is in the CO2 vapor generator of 182.4 kW followed by the CO2 turbine of 106 kW, then the CO2 condenser of 82.81 kW and then the CO2 pump 58.76 kW. The lowest exergy destruction rates occur in the single flash geothermal power plant components where the separator has exactly zero exergy destruction rate. The results also show that the combined power plant produces more power and has better efficiencies (first law and second law) than the stand-alone geothermal power plant. Finally, Nelder–Mead simplex method is applied to determine the optimal parameters such as separator pressure, power output and pumps input power and second law efficiency. The results show that the power plant should be operated at a lower pinch temperature to reduce damage to the environment. As the condenser pressure increases, the environmental damage effectiveness coefficient decreases sharply until it reaches the minimum value of 1.2 to 1.7 MPa and then starts to increase. The trend of the impact of sports on environmental improvement is exactly the opposite of the trend of the effectiveness of environmental damage. Therefore, from an environmental point of view, it is recommended to operate the gas turbine at a high inlet pressure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.