Energy and Exergy Analysis of the Kalina Cycle Based Combined Cycle Using Solar Heating

Gas and steam combined cycle has Brayton cycle and Rankine cycle as topping and bottoming cycles respectively. Gas based topping cycle has flue gases leaving at high temperature which are utilized in heat recovery steam generator for steam generation. The steam thus generated is used for running steam turbine in bottoming cycle. It is seen that the heat recovery steam generator although offers reasonable heat recovery from flue gases but the temperature variation profile of gas does not match with that of steam generation. The use of ammonia in place of steam as working fluid offers a good matching of temperature profile of flue gas and ammonia and thus has capability to offer effective utilization of waste heat. In present work thermodynamic analysis of Kalina cycle used in combined cycle has been carried out. It includes the performance evaluation in terms of ammonia mass concentration, turbine inlet temperature and cycle pressure ratio. The results show that on increasing the ammonia mass fraction the efficiency of the cycle decreases up to ammonia mass concentration of 0.7 but beyond that efficiency starts increasing. It also indicates that by installing the solar heating, there occurs a heat gain up to 5% as compared to without solar heating for any given operating parameters.