Modeling Comparison of a Two-Phase Mechanically Pumped Loop with a Conventional Ethylene Glycol Water Single-Phase Mechanically Pumped Loop for Fuel-Cell Cooling in TheMa4HERA

Abstract

The fuel-cell (FC) technology currently being considered to reduce aircraft greenhouse gas emissions may require large and heavy cooling systems. The paper introduces the two-phase (2Φ) Mechanically Pumped Loop (MPL) for FC cooling and compares it numerically with the conventional Ethylene Glycol Water (EGW) single-phase (1Φ) cooling system for a 1.2 MW heat-dissipation load. Considering an operating temperature of 90 °C, the system mass of the 2Φ MPL with and without an accumulator is found to be, respectively, 33% and 64% lower than the EGW system. Furthermore, the frontal area of the ram air heat exchanger (HX) was found to be 19% smaller, reducing ram air drag. An increase of the operating temperature to 130 °C was found to reduce the cooling system mass by 21% for the 1Φ MPL, and 22 to 29% for the 2Φ MPL. The frontal area of the ram air HX was found to be reduced by 44% and 40% for the 1Φ and 2Φ MPL, respectively. These results demonstrate the considerable performance gain of the 2Φ MPL over the 1Φ MPL for FC cooling, and the benefits of increasing the operating temperature for the cooling system.