High energy density miniature electrical and thermal power source using catalytic combustion of butane

This paper describes the development of a thermoelectric (TE) generator with a catalytic butane combustor. The TE generator is composed of a thermoelectric (TE) module, a catalytic combustor, an ejector to supply air to the combustor and an ignition heater. Liquid gases such as butane and propane are used as fuel. The ejector makes supersonic fuel jet from a Laval nozzle, and sucks air by viscous dragging and pressure drop due to the fuel jet. The prototyped ejector sucked air with 31.2 times larger volume of air, satisfying the requirements for the complete combustion of butane. However, the performance dramatically decreases with increase in back pressure. Therefore, to minimize the pressure loss of the combustor is necessary. The combustor without a load (TE module) achieved self-sustaining combustion and electrical ignition using butane as fuel. When the TE modules were attached to the combustor, however, butane combustion was impossible and the combustion efficiency of hydrogen decreased. The generation test was performed by attaching two TE modules to the combustor and using hydrogen as fuel. The conversion efficiency reached 1.8% at an output power of 276 mW. This study confirmed that the miniature TE generator is practical, if the performance of the combustor is improved.