Effect of updated data base and improved analysis on performance of radioisotope thermophotovoltaic converter

摘要

Previous analyses of RTPV space power systems published by the authors were based on a number of approximations employed to permit early dissemination of preliminary results pending availability of fuller experimental data needed to conduct more rigorous analyses. The shortcomings of the previously published analyses are addressed in the paper, which describes revised analyses based on experimental data of IR filter reflectivities and PV cell quantum efficiencies and current-voltage characteristics. The paper applies the revised test data and analyses to an illustrative converter design, using an OSC-generated computer program that also includes the effect of shadowing and ohmic losses by the cell's optimized grid lines, the use of accurate active-area fractions representing detailed converter designs, and the reduction in the required heat source-to-emitter heat flux due to radiation reflected by the inactive filter area and absorbed by the emitter. It details the effect of each analytical change on the converter's performance. The analytical results confirm that EDTEK's improved filters have greatly enhanced the performance of the RTPV generator. They also demonstrate that accurate accounting for the effect of reflection from the inactive filter area and absorption by the emitter results in a significant performance improvement. But they show that these improvements are not large enough to compensate for the adverse effect of replacing the previously used theoretical equations for the converter's open-circuit voltage and fill factor with measured values of those parameters achieved to date.