Hydrogen fuel storage/delivery for a diver heater using hydrogen catalytic reactions

The necessity for active diver heating during long duration, cold water, swimmer delivery vehicle (SDV) operations is well established. Alternative approaches to supply this active heating requirement have covered a wide range of technologies, including thermoelectric heaters, magnesium combustion, propane catalytic heating, and direct electrical resistive heating. While all of these methods have been shown to be capable of producing sufficient quantities of heat, each has its own inherent restrictions and interface issues when applied to an SDV operation. These issues include heater power consumption requirements that compete and detract from the power requirements for SDV propulsion, and heater packaging requirements in an already space-limited environment. A simple hydrogen catalytic combustion heater was tested as a breath heater for deep diving applications. The high heat production demonstrated during this testing suggested that this approach could also be used as a diver heater to potentially minimize package size and power requirements and yet meet all the diver heating requirements for long duration Naval Special Warfare missions. Preliminary analysis has shown that less than 0.4 kg of hydrogen could supply the 2 kW of heat needed to sustain up to 6 divers in 0°C water for up to 6 hours. This paper investigates the various methods to store and supply the hydrogen fuel.