sCO2 Cycle Selection for Waste Heat Recovery From Aircraft Engine

The reduction of emissions for any sector, such as aviation, can be done via alternative fuels (i.e., direct approach) and/or utilization of waste heat (i.e., indirect approach). With an indirect approach, waste heat recovery (WHR) systems can provide onboard electrical power and eliminate or reduce the need to produce electrical power with other systems. An engine with a WHR system could potentially produce similar power/thrust with less fuel consumption. WHR systems could have additional benefits for the engine core and bypass flow. This work is focused on the sCO2 power cycle selection for a potential WHR system for an aircraft engine based on a Leap-1B engine using H2 as the working fuel and NH3 as a fuel carrier. Several sCO2 power cycle layouts are investigated for each case, including simple, recuperative, re-compression, precompression, and split expansion. Optimization of the selected cycle layout for the maximum power requirement and heat availability to transfer to the NH3 line or bypass is performed. The results show potential benefits and disadvantages of each cycle layout and demonstrate that the WHR system can meet the 180-kW power generation requirement for the airplane and still provide significant heat to the NH3 line or bypass flow.