Upgrading gas turbine efficiency for sustainable power generation: An energy and exergy analyses

A comprehensive exergy and energy analyses of a General Electric model pg9171e 132-MW gas turbine power plant is presented in this research. Specifically, the research evaluates the performance and efficiency of gas turbine power plants under variable ambient temperatures throughout the year. Different operational parameters are used to assess the plants' energy and energy efficiency. An open Brayton cycle is used to analyse gas turbine energy. Modelling the energy efficiency and conducting exergy analyses for each part of the gas turbine cycle have determined the gas turbine exergy efficiency. The results show that the performance of gas turbine power plant is considerably affected by the ambient temperature. High inlet ambient temperatures can significantly reduce energy and exergy efficiencies. Based on the actual data gathered from the plant, the reduction in the generated power during summer is approximately 32 % compared to the design values. However, such a drop in output power is only 15 % when adopting an analytical model. Noticeably, it is found that the drop in generated power can compensate successfully when using fuel characterised by high firing temperatures such as high hydrogen blends. The exergy analyses results reveal that the exergy efficiency of the turbine and compressor are not affected by increasing ambient temperature, with 90 and 89 %, respectively. In comparison, it is reduced in the combustion chamber section by 86 %. Moreover, the exergy destruction is found to be in its maximum in the combustion chamber section, with 98.67 %, while it is 29.36 % and 14.72 % for turbine and compressor sections, respectively. Accordingly, the maximum contribution in the exergy destruction of plant components is the combustion chamber section of 68.99 %. Research findings can serve as a baseline for future comparisons and improvements in gas turbine performance levels. The exergy analyses pinpoint specific components within the power plants where energy quality degradation occurs, guiding targeted efficiency enhancements. In order to reduce greenhouse gas emissions and other pollutants, power plants must be more efficient.