Comparison analysis of two different concentrated photovoltaic/thermal-TEG hybrid systems

Abstract

To explore the novel structure and optimize the performance of the photovoltaic/thermal (PV/T) system, the linear Fresnel concentrating PV/T (LFPV/T) systems plus thermoelectric generator (TEG) with and without gravity-driven heat pipe (GHP) are investigated in this paper. GHP is an efficient heat transfer device, which could collect heat accumulated on PV to the hot side of TEG. TEG can convert heat into electrical energy with a temperature gradient. In this case, the GHP-LFPV/T-TEG system is proposed. However, the increased heat flux may rise the PV temperature and decrease the output of PV cells, so the water type LFPV/T-TEG system without GHP is introduced. This research focuses on the numerical study of the two systems and the comparative analysis of the performance is completed. The results show that the existence of GHP improved the thermal and comprehensive performance of the system and the output of TEG. After running for 7 h, the thermal efficiency and the comprehensive efficiency of the GHP-LFPV/T-TEG system were 10.23% and 2.55% respectively higher compared to those of the LFPV/T-TEG system, while the electrical efficiency and exergy efficiency were 2.91% and 1.56% lower under 800 W/m2 solar irradiation, 18 ℃ ambient temperature, and 15 ℃ initial water temperature. The TEG output of the GHP-LFPV/T-TEG system and the LFPV/T-TEG system was 13.64 kW and 6.41 kW respectively. Moreover, the influence of solar irradiation, concentration ratios, and TEG modules was also discussed.