Description: Thermal management presents a significant constraint on the achievable efficiency and power density of MW-scale electric motors for aircraft propulsion. High temperatures within the windings limit the maximum power density, reduce the lifetime of the winding insulation, and increase electrical losses resulting in lower efficiency. Innovative thermal management strategies can significantly enhance the performance of motors for electrified aircraft propulsion. In this SBIR program, Advanced Cooling Technologies, Inc. (ACT) is developing an innovative two-phase thermal transport system for high power electric motors that will augment traditional cooling solutions by efficiently extracting heat from difficult to cool areas. The two-phase thermal transport system will be fully passive, lightweight and scalable. The proposed technologies will improve waste heat rejection from motor windings allowing for increased power density and efficiency. The Phase I program successfully demonstrated the feasibility of the concept and presented an electric motor with a 60% increase in power density over a conventional design with comparable thermal performance. In the Phase II program, ACT will continue to lead the development and maturation of an innovative two-phase heat-transfer-based thermal management solution for electric motors. The goal of the Phase II program is to demonstrate an optimized design of an enhanced motor capable of power density of 20 kW/kg and efficiency of at least 98%.

Benefits: The two-phase thermal management technology proposed is relevant to several strategic thrusts outlined by NASA's Aeronautics Research Mission Directorate: “Ultra-Efficient Commercial Vehicles” and “Transition to Low-Carbon Propulsion”. NASA envisions a significant shift in commercial aircraft to ultra-efficient airframes and propulsion concepts utilizing electric or hybrid electric propulsion. Improved thermal management resulting from the proposed technology will enable significant increase in the power and torque density of electric motors.

The proposed technology is applicable to various motor architectures and sizes. It will find use in passenger aircraft, unmanned aircraft, and electric vertical takeoff and landing aircraft. In addition to the aviation industry, the need for high-performing motors in electric automobiles is rapidly growing as nearly all sectors of the transportation industry begin to electrify.