Environmental and Sustainability Aspects of an Aviation Auxiliary Power Unit Analyzed with the Aid of Exergy 2018-32-0071
During the past decade environmental and sustainability issues have become major problems to
overcome since they have caused regional and global consequences. This paper discusses the environmental and sustainability aspects of Gas Turbine (GT) based aviation Auxillary Power Unit (APU) with the aid of exergy. Exergy is a potential tool to determine exergy destructions and losses and their true magnitudes and exact locations. In this study some exergy based parameters such as: exergetic efficiency, waste exergy ratio, exergy recoverability ratio, exergy destruction ratio, environmental impact factor, and exergetic sustainability index are proposed and investigated. Cycle operating parameters of the gas turbine cycle based APU such as compressor-pressure-ratio (rp,c), Turbine Inlet Temperature (TIT) have been chosen for analysis. Mathematical modeling of the cycle has been done and the same has been coded in MATLAB. Results show that increasing waste exergy ratio decreases the exergetic efficiency and exergetic sustainability index. However, any increase in waste exergy ratio results in an increasing environmental impact of the GT cycle based APU. Exergetic efficiency, waste exergy ratio, exergy destruction ratio, environmental impact factor, and exergetic sustainability index are found to be 14.51%, 0.8549, 5.8917 and 0.16973 respectively for the overall cycle (rp,c = 3 and TIT =1300K). These results would be useful to make it more sustainable for future development.
Keywords: Exergy; Exergetic sustainability index; Auxillary Power Unit; Exergetic efficiency; Gas Turbine