Performance enhancement of combined cycle power plant using inlet air cooling by exhaust heat operated ammonia-water absorption refrigeration system

Abstract

Studies conducted on Brayton-Rankine combined cycle power plants have shown that the performance of its gas turbine unit and hence the overall performance of the plant can be improved by decreasing the compressor inlet air temperature. In these plants, a lot of low grade heat goes waste along with the exhaust gases. Absorption refrigeration systems always attract the users to utilize the low grade waste heat wherever it is available Therefore, in this work, a simulation model of an Indian combined cycle power plant coupled with exhaust heat operated ammonia-water absorption refrigeration system has been developed to investigate the performance of the combined system according to Indian atmospheric conditions which vary throughout the year. Energy and exergy analysis reveals that by having this arrangement, in summer season, an additional net power of 9440kW is developed thereby increasing the thermal efficiency of the plant by 1.193% and the exergy efficiency by 1.133%. But, in winter, it would further increase the power output by 400kW. As the North Indian atmospheric temperature varies from about 45°C in summer to about 3°C in winter, the variation of plant performance with the variation of ammonia condenser temperature has also been studied.