Design and Simulation of a Commercial Hybrid Electric Aircraft Thermal Management System

The baseline design of the Thermal Management System (TMS) of a parallel, hybrid electric aircraft engine for a commercial, single aisle aircraft with batteries for energy storage has been completed. The Hybrid Electric Propulsion (HEP) system features a low spool motor to assist the propulsor, its attendant motor drive, propulsion batteries, and supplementary batteries to cover TMS electric loads during electric augmentation on takeoff and climb. The TMS further includes the heat loads sunk to engine oil including bearings, the fan drive system, and the accessory gearbox. The model was executed under hot day conditions (ISA + 15) over the mission sizing points when electric augmentation is active. REHEATS, a proprietary, object-oriented modeling tool created at the United Technologies Research Center, was used to model the TMS and find the solution with minimal fuel consumption. This study establishes a baseline for comparison of energy storage using batteries for future comparison. The results predict that the TMS of a HEP aircraft increases fuel consumption by 3.4% during takeoff, climb, and cruise.