Keywords: ammonia–water mixture, ammonia concentration, anergy, exergy analysis, Rankine cycle, regeneration, power generation, second law, thermodynamics, exhausted heat source, coolant, heat exchangers, exergy efficiency
Comparative exergy analysis of ammonia–water based Rankine cycles with and without regeneration
Power generation systems using an ammonia–water mixture instead of water as working fluid have attracted much research interest over the past 20 years, since they have a potential to convert more energy in low–grade heat source into power and to improve the power generating processes in several ways. In this work comparative exergy analysis based on the second law of thermodynamics is carried out for ammonia–water based Rankine (AWR) and regenerative Rankine (AWRR) power generation cycles. Special attention is paid to analyse the effect of ammonia concentration in working fluid on the anergies in various system components including exhausted heat source and coolant, heat exchangers as well as the exergy efficiency. The analysis found that the anergies are significantly affected by ammonia concentration in working fluid. The main source for the anergy in the systems is strongly dependent on ammonia concentration and turbine inlet pressure, and it is quite different in AWR and AWRR systems.