Optimization Modeling of Multiple Spectral Control Components for High Thermophotovoltaic (TPV) Efficiency

摘要

Several methods of using spectral control for improving the efficiency of a thermophotovoltaic (TPV) system have been developed and demonstrated. These methods include spectrally selective emitters on the hot side emitter, cold side filters, and back surface reflectors. Each approach has been shown to improve the efficiency of a TPV system by either suppressing the emission of photons that cannot be converted to electrical current or reflecting those low energy photons back to the emitter for recuperation. Modeling the full TPV system and cavity has shown that using multiple spectral control components is an effective means of optimizing system performance while reducing tolerance requirements, complexity, and cost of the individual spectral control components. For example, use of a front surface filter and a back surface reflector reduces the tolerance on the filter edge slope and spectral position. The front surface filter can be further refined to yield improved system efficiency with the same or fewer material layers and higher manufacturing yield. This paper presents the results of a design study by which multiple spectral control strategies are used to improve performance, relax the cost drivers, or mitigate technical concerns of the individual approaches. System efficiency and predicted power density are modeled and used as performance merits for evaluating individual spectral control approaches and optimized multiple components spectral control designs. The modeling approaches used take into account the TPV cell's optical performance, the performance of the emitter, and the optical cavity. The use of spectral emitters with front surface filters allows for a simpler filter, eliminating the need for a tandem plasma filter. This significantly reduces the cost of the filter and parasitic absorption within the filter with marginal impact on performance.