Thermal Analysis of Aircraft Auxiliary Power Unit: Application of Chemical Looping Combustion

An “APU” (Auxiliary Power Unit) is a small gas turbine engine to provide supplementary power to an aircraft and is located at the tails of larger jets. APU generators provide auxiliary electrical power for running aircraft systems on the ground. Applications include powering environmental systems for pre-cooling or preheating the cabin, and providing power for crew functions such as preflight, cabin cleanup, and galley (kitchen) operation and long-haul airliners must be started using pneumatic power of APU compressor. The Honeywell 131-9A gas turbine APU has 440 kW shaft power and 90 kW electric generator consuming 120 kg fuel/hour. Here the traditional combustor of the APU is proposed to be replaced by a chemical-looping-combustion (CLC) system. CLC system consist of two reactor one is oxidation reactor (air reactor) and the other is reduction reactor (fuel reactor).The system is fluidized bed system in which activated metal-oxide(MeO) participates and circulates between the reactors .The metal-oxide (MeO) provides oxygen for combustion in the fuel reactor. The reduced metal is then transferred to air reactor before being reintroduced to the fuel reactor to complete the process. In this process isolation of fuel from air simplifies chemical reaction related to combustion and using oxygen without nitrogen tends to eliminate formation of NOx from flue gases which is basically CO2 and water vapor. The proposed APU gas turbine with CLC combustion is expected to revolutionize aviation transportation as it is more eco-friendly. The maximum gas temperature at the exit of CLC is 1300K which is similar to maximum gas turbine cycle temperature hence the integration of CLC system to gas turbine APU is promising . Thermal analysis of the chemical looping combustion system is proposed to be reported. Also likely emission benefits from the proposed system would also be reported.