The Study of Ambient Temperature Effects on Exergy Losses of a Heat Recovery Steam Generator

One of the major effective parameters on the combined cycle power plants’ performance is the ambient temperature. In this paper, the thermal and exergy analyses of a 400 MW combined cycle power plant is presented. The objective of this study is to investigate the effects of ambient temperature variation on the exergy loss of the Heat Recovery Steam Generator (HRSG). The HRSGs of this CCPP are equipped with the supplementary firing. The estimations are done for the yearly minimum average, yearly average and yearly maximum temperatures. The results have been used to evaluate the exergy losses for each element of HRSG. The exergy losses of these devices are presented for all above mentioned temperatures and the effects of temperature variation are discussed to find out the most irreversible parts of HRSG. The results show that for the fired and unfired modes, the exergy loss in 1

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HP-EVP is more than other parts. The results also show that the exergy losses have a minimum point at 19°C which is the design temperature. Moreover, the results reveal that the supplementary firing increases the exergy loss of HRSG as well.