Liquid Cooled System for Aircraft Power Electronics Cooling

The shift to more electric aircraft presents many electronics packaging and thermal challenges. Innovation in both cooling and mechanical packaging concepts is needed to integrate the required equipment into the aircraft. Heat dissipations in electronics can be significant, and be beyond the cooling capability of existing Electrical Equipment (EE) bay capabilities. The location of electronics in an aircraft is based on usage of the equipment. This presents thermal challenges because these locations are likely difficult to cool. The cooling system must acquire heat at the electronics box and transport the heat to the ultimate heat sink for rejection. There are only two options for heat rejection: either ram/fan air, or fuel. Fuel has limited thermal mass and also quantity of fuel and hence thermal mass varies during flight phase. Amount of heat that can be transferred to fuel is thus limited. Almost all options ultimately reject their heat to ram/fan air. Liquid cooling facilitates large transport distances, high heat fluxes and accompanying size and weight reductions for electronics, yet ultimately rejects heat to air. The complexities of integrating a large liquid loop on a commercial aircraft are numerous but solvable. A successful solution requires an integrated system that is easy to maintain, pays close attention to detail, and is cost effective. This paper will provide an overview of the above systems and integration challenges.