Graded Heat Exchangers for Cryogenic Thermal Management of Power Devices of Liquid Hydrogen-Electric Aircraft

Thermal management of electric aircraft using open-loop liquid hydrogen as a heat sink and closed-loop gaseous helium circulation secondary cooling loops for multiple high-temperature superconducting (HTS) and other power devices is discussed. Thermal management was developed for the conceptual liquid hydrogen-fueled aircraft concept as part of the Integrated Zero-Emission Aviation (IZEA). The partitioned, graded heat exchanger concept was adopted to produce multiple secondary cooling loops. The required mass flow rates of the secondary helium loops of each power device were calculated for the flight's takeoff, cruise, and landing phases. The thermal management protocol developed uses the mass of liquid hydrogen used as fuel to limit the cooling budget to operate two 7.5 MW HTS generators (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$25-45 ~\mathrm{K}$</tex>), HTS cables (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$50-70 ~\mathrm{K}$</tex>), cryogenic busbars (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$80-100 ~\mathrm{K}$</tex>), power conversion systems, and motors. The analysis supports the design of cryogenic loop thermal management systems for system-level optimization of the IZEA electric aircraft.