Design of Ducted Heat Exchanger for Proton Exchange Membrane Fuel Cell on Electric Aircraft

This paper will explain fuel cell (FC) electrical power and required MW-level heat rejection system on fuel cell powered electrical aircraft. We use a computational model to calculate heat flux, drag, specific cooling power and coolant pumping power during taxi, takeoff, climb, acceleration and cruise. The effect of altitude and aircraft speed on ducted heat exchanger (DHEX) will be explained. The calculated results enable engineers to optimize the ratio of duct inlet size to radiator core size according to specific parameters, such as drag, cooling power, and volume of ducted heat exchanger. While DHEX is effective for cooling in most flight phases, it can't provide enough cooling power during takeoff due to limited air intake and high ground temperatures. This insufficient cooling capacity necessitates the use of a hybrid power system combining FC and turboelectric generator (TEG) for takeoff.