Session: K12-02 Aerospace Heat Transfer II

Paper Number: 114340

114340 - A Hybrid Single/two Phase Cooling Approach Enabling Power Dense Electric Motors for Next Generation All-Electric Aircraft 

With increasing requirements for reduction in carbon emissions, aircraft propulsion technology is also being explored for potential electrification. Such all-electric aircraft will require high power, lightweight and efficient electric motors for propulsion. We present a hybrid and integrated thermal management approach that enables high power electric motors for next generation all-electric aircraft. Our approach utilizes a mini-channel heatsink using a high glycol content ethylene glycol and water mixture as the default cooler in tandem with a thermal energy storage (TES) module that leverages the latent heat capacity of a working fluid (e.g., water) to handle the excess heat during flight takeoff. In the experiments reported here, copper windings with inserted cartridge heaters were used to simulate motor losses (ac and dc), and these windings were coated with a novel polymer nanocomposite insulation, which provides good electrical insulation and lower thermal resistance compared to other commercially available ones. The mini-channel heatsink was intentionally designed to minimize thermal resistance, hydrodynamic losses and electromagnetic eddy current losses. We performed both steady state and transient tests to simulate typical flight profiles for aircraft cruising and take-off, respectively. We also conducted tests with and without the TES component to highlight its capabilities and critical role in achieving the high‑power density electric motor. Our experiments demonstrate that the hybrid system not only enables the high‑power density (by minimizing the thermal load of the single-phase heatsink system), it also reduces the peak temperature of the windings which is critical to operational longevity, insulation coating lifetimes and higher motor efficiency for its reduced electrical resistivity. The hybrid and integrated thermal management approach enables a motor power density of »13 kW/kg which is >2* the state-of-the-art. The hybrid thermal management approach presented here facilitates a viable pathway for next generation light weight, robust and high-performance electrical motor technology for commercial aircraft.

Presenting Author: Shiyu Zhang Texas A&M University