The exergy and energy level analysis of a combined cooling, heating and power system driven by a small scale gas turbine at off design condition

Abstract

This paper presents the off design performance analysis of a combined cooling, heating, and power (CCHP) system consisting of a small-scale gas turbine, an exhaust-fired double-effect absorption chiller, and a heat exchanger. The energy and exergy analyses of the CCHP system are investigated under the rated and part-load conditions. Energy level analysis is implemented on the energy conversion processes to reveal the mechanisms of the deterioration of the CCHP performance under part-load conditions. The results show that the CCHP system is energy saving when the power output of the gas turbine exceeds 30% of the full load. It is also found that the CO2 emission of the CCHP system reduced by 66.7%–70.5%, compared with conventional separation system, when the power output of gas turbine increased from about 30% to 100%. Energy level results reveal that the combustor of the small-scale gas turbine mainly contributed to the deteriorated performance of the CCHP system. In addition, a case study is carried out to illustrate the advantage of using dynamic data in the performance assessment. The case results indicate that using off-design data leads to a more realistic evaluation of the CCHP system.