Cooling System Design for PEM Fuel Cell Powered Air Vehicles
Memorandum rept. Jan 2007-Dec 2009
NAVAL RESEARCH LAB WASHINGTON DC CHEMICAL DYNAMICS AND DIAGNOSTICS BRANCH
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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 55 C. The combined fuel cellCHE balance model is applicable with minor modifications to other PEMFC systems utilizing a CHE for cooling.
- Pilotless Aircraft
- Electrochemical Energy Storage