Exergo-environmental Analysis of Basic and Intercooled-Recuperated Gas Turbine based Aviation Auxiliary Power Unit

This paper deals with the exergo-environmental analysis of gas turbine with possible application as aviation auxiliary-power-unit (APU). The present work reports a comparison of thermodynamic performance, NOx and CO emission for basic gas turbine cycle (BGT) and intercooled-recuperated gas turbine (IcRcGT) cycle based engines for possible use by the aviation industry as auxiliary power unit (APU). In addition to this environmental sustainability index of these two cycles is also presented. Various cycle operating parameters such as compressor-pressure-ratio (r_p,c), combustor-primary-zone-temperature, equivalence-ratio, and residence time have been chosen for analysis of the cycles. Mathematical modeling of the cycles has been done and the same have been coded in MATLAB. Results show that IcRcGT cycle exhibits higher gas turbine power output and gas turbine efficiency in comparison to BGT cycle for the same r_p,c and turbine inlet temperature (TIT). Percentage exergy destruction for combustion chamber has been found to be lower for IcRcGT cycle as compared to BGT cycle. NOx and CO emission are higher in case of IcRcGT cycle as compared to BGT cycle. Adoption of the proposed scheme i.e. IcRcGT cycle based APU promises to deliver enhanced performance i.e. thermal efficiency of around 10.62 percentage points higher thermal efficiency as compared to traditional BGT based APU (r_p,c = 2.6 and TIT = 1400K). Also for the proposed APU system, percentage exergy destruction for combustion chamber is reduced by around 14.95% and by 13.18% for the overall cycle (r_p,c = 3.8 and TIT = 1300K). Also, IcRcGT cycle is more sustainable aviation APU technology as compared to BGT cycle.