Effects of near-field radiation and hyperbolic modes on a TPV system

Abstract

Effects of near-field radiation and hyperbolic modes on a thermophotovoltaic (TPV) system are investigated through an electricity generation experiment. A pillar-array structured emitter is introduced as a medium that supports the hyperbolic modes. An emitter temperature of 500 °C is applied while a TPV cell temperature is successfully maintained at 10-16 °C. Furthermore, a nanoscale gap between an emitter and a TPV cell is created by four SiO₂ spacers and can be verified. A spacer height is controlled by sputtering time. Ten schottky diodes are used as TPV cells in the experiment. From the investigation, a trend of experimental results shows arguably good agreement with a numerical trend especially in a flat emitter case. The hyperbolic modes are shown to contribute to enhancement of power output. Nevertheless, there exists reduction of power output in 40% of all experimental results. Hence, there are possibly other phenomena apart from the hyperbolic modes that affect the radiative heat transfer. The near-field effect is detected in all experiments and 75% of all experimental results show good agreement with the numerical results. These findings provide areas for improvement of TPV system in both numerical and experimental aspects and will be beneficial for the future design of TPV system.