Studies on a heat-recirculating microemitter for a micro thermophotovoltaic system

A new microemitter (microcombustor) configuration for a micro thermophotovoltaic system in which thermal energy is directly converted into electrical energy through thermal radiation was investigated experimentally and computationally. The microemitter as a thermal heat source was designed for a 1–10 W power-generating micro thermophotovoltaic system. To satisfy the primary requirements for designing the microemitter (stable burning in the small confinement, maximum heat transfer through the emitting walls, but uniform distribution of temperature along the walls), the present microemitter is cylindrical with an annular-type shield to apply for the heat-recirculation concept. Results show that the heat recirculation substantially improves the performance of the microemitter: the observed and predicted thermal radiation from the microemitter walls indicated that heat generated in the microemitter is uniformly emitted. Thus, the present microemitter configuration can be applied to the practical micro thermophotovoltaic systems without any moving parts (hence frictional losses and clearance problems are avoided). Ratios of the inner radius of the shield to the gap between the shield and microemitter walls and the microemitter wall thickness substantially affect thermal characteristics.