| As one of the most advanced power solutions presently, thermophotovoltaic (TPV) system converts thermal radiation from man-made heat source into electricity by photovoltaic (PV) cell. It utilizes the same principle as do PV system, namely the photoelectric effect of semiconductor. Due to the small distance of the man-made heat source, the power-density output of the TPV system is much higher than the PV system, approaching a few Watt/cm2, stably without being affected by any weather condition. This is the most significant advantage of TPV system. Other advantages include versatile fuel-usage, quiet operation, low maintenance, safe, pollution free and possibility for cogeneration of electricity and heat. All those make the TPV applications in the field of industry, commerce, military and aerospace very promising and attractive.A TPV device consists of a heat source, a radiator (emitter), a TPV cell array, a photon-recycle system and an energy-management unit. The heat source, which provides the necessary radiation energy, can be the fuel combustion, nuclear or solar energy. The radiator, which radiative the energy from the heat source towards the TPV cells includes gray-body radiator and selective radiator. The TPV cells, which converts the received radiation into electricity outputs, is the pivotal component of the system and therefore dominates the system performance. The photon-recycle system, which recycles out-band photons to reduce the energy waste, can be classified into two categories, the front filter and backside reflector (or the combination of both). The energy-management unit controls the output, cooling and waste-heat recovery of the system. Present researches mainly focus on the advance technology of those separate components and the demonstration of system prototypes.The key components of the TPV system are the radiator, the TPV cells and the photon-recycle system, which compose the core of the system, namely the thermal radiation-electricity module. In the primary investigation research on the TPV system performance, physical and numerical model of this module is constructed. Current/voltage characteristics of the system consisting of a SiC gray-body emitter and GaSb or Si PV cells are obtained. Influences of the emitter temperature and the cell temperatures on the performance of the system consisting of a SiC emitter with GaSb cells are analyzed, respectively. The power-density output as well as the cell efficiency increases with the emitter temperature. However, the rise of the cell temperature leads to negative effects. Whereafter, the radiative energy distribution of a selective emitter matching GaSb cell is discussed. The selective emitter cuts down the unusable radiative energy remarkably comparing with a SiC emitter, and thus improves the system performance significantly.In the TPV system, the selective radiator and the photon-recycle system are so called spectral-control components, which decide the spectral efficiency of the system and further contributes to the system efficiency. Considering that the spectral-control components are the very key components for high-performance systems, this paper presents a detailed theoretical and experimental discussions on the transparent conducting oxides (TCOs) as well as one dimensional (1D) Si/SiO2 photonic crystal (PhC) filter matching TPV systems based on GaSb converter.In the analysis and optimization of TCOs filter, the model of TCOs filter is constructed and the influence of the carrier concentration as well as mobility on the spectral properties is analyzed. The optimal carrier concentration and film thickness are evaluated for TPV system based on GaSb converter with Al2O3/Er3Al3O12 eutectic ceramic selective radiator as well as SiC gray-body radiator varying from 1400 K to 1600 K. At last, the influence of the quartz thickness on the filter properties is discussed, and the performance of the system consisting of the Al2O3/Er3Al5O12 selective radiator, the TCOs filter and GaSb cells is investigated.In the development of 1D Si/SiO2 PhC filter, the theoretical model of 1D Si/SiO2 PC filter is constructed, and the issue that large oscillations around the characteristic wavelength of GaSb cell in the pass band of 1D PhC filter of (L/2HL/2)5 structure leads to a discount on the system performance is pointed out. A modified 1D Si/SiO2 PhC filter of [1.10(L/2HL/2)](L/2HL/2)3[1.10(L/2HL/2)] is designed based on the theory of equivalent refractive of symmetry unit. In the modified structure, the 3 middle units remain unchanged while the left and right units serve as the refractive match units. Simulation results indicate that the transmittance around the characteristic wavelength of the modified PhC filter is improved remarkably and the transmission of long-wavelength photons are also inhibited. The spectral efficiency and power-density output of the system with a blackbody radiator at 1250℃can be improved 10% by adopting the modified 1D PhC filter comparing to the original 1D PhC filter, the cell efficiency is also improved at a certain extent. Both PhC filter samples of the modified and original structures were prepared through a magnetron sputtering process. The cross-section SEM indicates that the structures of the prepared samples approximately match the design and the measured spectral reflectance and transmittance show good coherence with the simulation.In the thermal analysis of TPV system using the radiation resistor network method, the radiative heat transfer model of a typical medium-temperature TPV reported by L M Fraas is constructed by adopting the radiation resistor network method, the advantages of which include simple modeling and short computation time comparing with the Monte Carlo (M-C) method. However, in the usual solving process no consideration of the wavelength-shift for the photons when passing the quartz envelop will lead to violation of the spectral emissive power density pf the quartz with the Planck's Law. Whereafter, the model is improved by adopting a fictitious monochromatic heat source. This method ignores the detailed process of the wavelength shift, so it can predigest the complexity of the model and reduce the computation time. The calculated radiative heat flux, spectral efficiency and the equivalent radiative temperature of the quartz envelop from the improved model fit better with the results from M-C model in the literature.
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