Optimization of an improved power cycle for geothermal applications in Iran

Abstract Geothermal heat sources are promising renewable resources of energy. In this paper, a novel ammonia-water power cycle was designed considering the geothermal resources in Iran. This cycle was analyzed and the effects of ammonia fraction and boiler pressure on its performance were investigated. At the first, Sabalan geothermal field with temperature of 456K was studied. For this geothermal source, the effects of various ammonia fractions were perused in the boiler pressure of 25 bar. The results showed that the ammonia concentration of 0.855 led to the best performance. Also, investigating the boiler pressure at the constant concentration (0.855) indicated that the maximum efficiency happened at 35 bar. Based on genetic algorithm, the simultaneous effects of various concentrations and pressures on the performance of the ammonia-water cycle were surveyed and the optimum values were found for Sabalan source. So that, at the source temperature of 456K, the optimum concentration and pressure were obtained 0.85 and 36 bar, respectively. Finally, the optimum conditions for several geothermal source temperatures in Iran were presented within a table. Moreover, at the same sources, the presented optimized cycle was compared with other cycles in the literatures. The results indicated that the improved cycle at optimum conditions had higher efficiency.