Thermal modelling of TPV systems

Thermophotovoltaic (TPV) systems are rapidly becoming a potential alternative to replace large batteries partially (or totally) in power applications. A selective emitter, maintained at high temperature, radiates energy which is converted to electrical power using high efficiency photovoltaic (PV) cells. Thermal management of TPV systems is complex as the PV cells operating temperature must be kept below 80°C to maximise their efficiency. We have used numerical modelling to find a thermal management solution. In TPV systems, unlike typical electronic systems, radiation heat transfer must be maximised. However, inherent radiation losses - radiation not converted to electrical power - will contribute to increased PV cells temperature. This paper describes an iterative simulation method specially developed for TPV systems. The first step is to use an analytical, wavelength-dependent, radiation model to calculate the radiation heat transfer from the emitter to the cells. Knowing the internal efficiency of the cells, it is then possible to calculate the radiation losses for the system. Next these losses are incorporated into a standard computational fluid dynamics (CFD) thermal modelling package (conduction-convection) as a heat source. The temperature distribution calculated by CFD is fed back to the radiation model. This iterative procedure continues until the overall solution converges.