Transient investigation of a parallel vapor compression cycle for electric aircraft

The aviation industry faces the challenge of balancing emission reduction with the increasing demand for passenger flights. Electric aircraft offer a promising solution by eliminating emissions during flight, but their components necessitate an efficient thermal management system to achieve the restricted operating temperatures. A vapor compression cycle presents a viable approach to maintain component temperatures near or below ambient levels, even at hot ground-level temperatures. By using parallel evaporators directly connected to the electric components, multiple heat sources across an aircraft can be addressed. Despite its potential, the impact of such a system on aircraft performance remains unexplored, representing a crucial research area for future aircraft generations. To investigate this, an experimental test rig has been constructed to demonstrate the cooling system’s feasibility with the refrigerant R1336mzz(Z) and to validate a transient simulation model in MATLAB Simulink. The effect of additional drag, mass, and power consumption is analyzed over a flight mission. All factors are combined into a single objective parameter – the additional thrust requirement of the aircraft – derived from flight physics. The vapor compression cycle consistently outperforms a comparable liquid cooling cycle for all examined maximum component temperatures up to 70 °C. A temperature lift of 40 K is identified as optimal, minimizing drag and outweighing the power increase due to the compressor. The studied vapor compression cycle achieves an airflow-dependent cooling capacity of up to 60 kW kg^-1s and a mass-dependent cooling capacity of 0.6 kW kg^-1, highlighting its effectiveness and potential for enhancing electric aircraft performance.