Abstract
Combined cycle power plants have a key role in power generation. In this paper, a thermodynamic analysis with different ambient temperatures has been employed for the combined gas and steam turbine power plant is located at Zawiya, Libya, with and without steam injection into the combustion chamber of the cycle. Two cases for the combined cycle have been examined in different ambient temperatures. The first case is the normal combined cycle, the second case is the combined cycle with steam injection, where it injects steam into the combustion chamber to compensate for the increase in the amount of fuel needed at a constant power output when increasing the ambient temperatures, or to enhance the cycle performance where it finds the power output decreases with increasing ambient temperatures. In this paper, also exergy destruction of each component of the combined cycle at different inlet temperatures was evaluated utilizing exergy analysis. The results show that improvement in the thermal performance of the combined cycle can be achieved by injecting steam into the combustion chamber, where power output is increased by 10 % and efficiency of the combined cycle is improved by about 10 %. Gas turbine combustion chamber has the greatest exergy destruction compared to other components and representing about 13 % increase in exergy losses when the steam injection has been used, the second major exergy loss is in the heat exchanger.