Power Generation Enhancement by Using a Parabolic Solar Trough Collector Linked With an Absorption Refrigeration Cycle

Abstract

Benghazi-North 750 MW combined cycle power plant is subjected to large ambient air temperature fluctuations throughout the year, which adversely affects its overall thermal performance. Lowering inlet ambient air temperature of its gas turbine unit, by keeping it at or close to the designed conditions, will maintain a good performance and fixing overall cycle thermal efficiency. Linking of parabolic solar trough collectors and LiBr-H2O absorption chiller to this power plant would solve this problem. This can be done, by capturing solar thermal energy and employing it as a power source for the absorption chiller, in order to provide a low air temperature inlet to the gas turbine unit. A mathematical model of the existing combined cycle was constructed and simulated by using a software package to examine effects of these modifications on overall cycle performance. The simulation results of the combined cycle gas turbine unit performance without any modifications revealed that any increase in ambient air temperature will lead to a great reduction in the output electrical power. For instance, when an average maximum ambient air temperature reached 31.5 o C, which occurs in May, the net gas turbine unit output electrical power decreases by 12.42 % to reach 261 MW, whereas 298 MW at ISO conditions. However, by adding parabolic solar trough collectors, the obtained cooling capacity reached 9.77 MW at an inlet cooling ambient air temperature of 13.4 o C. This cooling capacity would augment the gas turbine electrical power output by 14.18 %, minimize electricity fluctuations and also reduce greenhouse gas emissions by 2.35 %. The obtained results were in good agreement with previous theoretical and experimental studies.