Performance comparison of two micro-channel heat pipe LFPV/T systems plus thermoelectric generators with and without aerogel glazing

Highlights: • A novel PV/T system combined with Fresnel lens, MCHP, and TEG is proposed. • The LFPV/T-MCHP-TEG system with aerogel is compared with that without aerogel. • The system with aerogel has enhanced thermal performance and TEG's performance. • The system without aerogel has great electrical and comprehensive performance. • The impact of different parameters is discussed. A novel photovoltaic/thermal (PV/T) system is designed, which combines Fresnel lens (LF) for linear concentrating, micro-channel heat pipe (MCHP) and thermoelectric generators (TEG) to achieve high electrical and thermal output. Aerogel possesses the characteristic of good heat preservation and thermal insulation, thus, applying transparent aerogel glazing to the LF-PV/T-MCHP-TEG system is proposed, to investigate the effects of the different thicknesses of aerogel on performance and compare the system with the no-aerogel system. The results show that adding aerogel enhanced the thermal performance and TEG's performance. The thermal efficiency of the system with 3 cm aerogel was 25.0% under 800 W/m² irradiation, 3 concentration ratio, 18 °C ambient temperature, and 15 °C initial water temperature, while that of the no-aerogel system was 23.4%. Besides, using aerogel increased the power of TEG by 6 kJ. Nevertheless, the electrical efficiency of PV and overall efficiency of the LFPV/T-MCHP-TEG system with aerogel were 1.8% and 3.0% lower than those of the no-aerogel system under the same conditions. Therefore, there had to be a trade-off between the benefits of better thermal performance and better electrical performance. Furthermore, the influence of TEG modules, solar irradiation, concentration ratios, initial water temperature, and ambient temperature was also discussed.