Parametric characteristics and optimization of a novel near-field thermophotovoltaic and thermoelectric hybrid system for energy harvest

Abstract In this study, a novel near-field thermophotovoltaic (NFTPV) and thermoelectric (TE) hybrid system is proposed to achieve efficient energy cascade conversion, where TE is used to harvest the thermal energy discharged by NFTPV. Based on the physical model, the performance of the hybrid system with tungsten emitter and InAs cell is analyzed and optimized through numerical simulation. The effect of operating parameters such as emitter and cell temperature, applied voltage of TPV cell and vacuum gap on the performance of hybrid system is investigated. The results indicate that the NFTPV-TE hybrid system has significant advantages over single NFTPV system. When the emitter temperature is 1000 K, the efficiency of the NFTPV-TE hybrid system is about 3.5–9.5 percent points higher than that of single NFTPV, and the optimal system power increases by 6–16%. Each parameter of NFTPV-TE hybrid system has its optimal range, which can ensure the high efficiency and output power of the system simultaneously. The NFTPV-TE hybrid system is not suitable for the waste heat recovery under low-temperature conditions. However, it is very suitable for the application of NFTPV-TE in solar energy conversion since the optimized cell temperature is low. NFTPV-TE hybrid system can overcome the limitation of single NFTPV efficiency under high-temperature combustion conditions. The efficiency of the hybrid system can reach 45.8% when the emitter temperature is 2000 K, which is 6 percentage points higher than that of single NF-TPV system. This study indicates the significant value of NFTPV-TE hybrid system in high-temperature engineering and provides guidance for the practical application of NFTPV system.