Cooling System Design for PEM Fuel Cell Powered Air Vehicles

摘要

The Naval Research Laboratory (NRL) has developed a proton exchange membrane fuel cell (PEMFC) powered unmanned air vehicle (UAV) called the Ion Tiger. The Ion Tiger fuel cell produces 600 W electric (gross) and a comparable amount of waste heat that must be rejected by a cooling system. This study was undertaken to design a cooling system for the Ion Tiger and investigate cooling approaches that may be suitable for future PEMFC powered air vehicles. The performance of several flat plate radiators and compact heat exchangers (CHEs) were evaluated, both in a wind tunnel and in the laboratory. The flat plate radiators were too heavy and occupied too large an area to be practical; a CHE was the lightest and smallest option. A simple thermal model for the flat plate radiators was developed and then used to explain the experimental results. An energy balance model of the fuel cell system and a UA model of the selected CHE were used to size the cooling system. The energy balance and UA models were validated using test flight data. The models were also used to explore the performance envelop of the cooling system which is lightweight, consumes little parasitic power and enables the Ion Tiger to fly continuously at full power in ambient air temperatures up to 55C. The combined fuel cell/CHE balance model is applicable (with minor modifications) to other PEMFC systems utilizing a CHE for cooling.