Effects of micropore characteristics in the metal skeleton on heat and mass transfer in an open foam structure for thermal management in the hydrogen UAV

Abstract

Aiming at solving the heat dissipation problem in a hydrogen unmanned aerial vehicle (UAV), this work uses an open metal foam as the enhanced heat transfer device in the air-cooling channel. The method of improving comprehensive heat transfer capacity and weight reduction by controlling the micropore directions and sizes in the metal skeleton is proposed. The real open cell metal foam structures are scanned and restructured using the X-ray computed tomography imaging system and corresponding computer software. The effects of micropore directions and sizes in the skeleton on pressure drops, conjugate heat transfer, volumetric heat transfer coefficient, comprehensive heat transfer capacity as well as weight reduction are discussed with the inlet velocity ranging from 10 m/s to 80 m/s. Results find that the micropore direction parallel to flow owns a higher comprehensive heat transfer capacity compared with that vertical to flow. There are existing a competitive relationship between heat conduction and heat convection in the metal skeleton. When the micropore size is 0.01, a best enhanced heat dissipation performance can be achieved. The structure with micropore size of 0.03 has a 8.49% weight reduction and 4.72–5.91% improvement of comprehensive heat transfer performance compared with that of the structure without micropores. The above findings can be applied to design a light and high comprehensive heat transfer device in the hydrogen UAV.