Burner, emitter, and recuperator development for lightweight thermophotovoltaic power supply

Like batteries, thermophotovoltaic generators produce DC electricity quietly. TPV uses infrared photovoltaic cells to convert infrared radiation from a combustion heated ceramic IR emitter. However, because the specific energy in a hydrocarbon fuel like propane or butane is 12,900 Wh/kg, much larger than the specific energy of 145 Wh/kg for a Li-ion battery, TPV is very promising as a lightweight DC power supply. A portable cylindrical thermophotovoltaic (TPV) battery replacement concept has been previously described. It consists of a cylindrical TPV receiver assembly using simple diffused junction GaSb IR cells along with a novel omega recuperator and a novel doped ceramic matched IR emitter. For high energy conversion efficiency, it is very important to match the IR spectrum emitted with the IR PV receiver cells. While the GaSb IR cells have been previously demonstrated, development and demonstrations of the omega recuperator and the IR matched emitter are described for the first time here. The matched IR emitter consists of NiO doped MgO ceramic rods arrayed in a 26 mm diameter picket fence configuration. A burner, emitter, and recuperator test station is described consisting of this picket fence emitter heated at up to 1300 C by propane combustion along with an omega recuperator to preheat the combustion air. The emitted IR intensity is measured with a single GaSb test cell. Given a TPV conversion efficiency of 10%, this lightweight TPV cylinder along with 1.8 kg of fuel promises a very high specific energy of approximately 700 Wh/kg. This specific energy is 5 times higher than the specific energy for a Li-ion battery with a similar power rating making this TPV unit very lightweight. The key is the goal of 10% system efficiency. Progress towards achieving this goal is described here.