Efficiency improvement of a steam power plant through solar repowering

Currently, fossil fuel power plants generate about 93.2% of Iran's electricity network. Negative growth of average efficiency of thermal power plants in the past years necessitates investment and research in order to increase their efficiency. In this paper, the use of solar thermal energy for parallel feed water heating repowering of Isfahan Mohammad Montazeri power plant units is evaluated. To this end, seven separate plans are proposed. At the time of replacing all high-pressure feed water heaters with solar collectors, net energy and exergy efficiencies increased by 9.5% compared to the simple cycle reaching 35.21% and 36.85%, respectively.