Experimental investigation on the performance of MXene/C-dot hybrid nanofluid-based photovoltaic/thermal system: An Energy, Exergy, and Enviro-Economic analysis

Nanofluids (NFs) with exceptional heat transfer properties are increasingly being adopted in solar collectors as heat transfer fluid (HTF). Hybrid photovoltaic thermal systems are becoming more popular because they increase overall efficiency by producing both high- and low-grade electricity. This research focuses on the application of thermally efficient NFs for enhancing the thermal and electrical output of a photovoltaic/thermal (PV/T) system. Indoor experimental investigation was conducted on the PV/T system to find the thermally efficient HTF. Carbon quantum dot (C-dot), MXene and MXene/C-dot hybrid NFs were selected for experimentation. Thermo-economic factors (thermal conductivity, volumetric heat capacity, thermal property degradation rate, and cost) were used to optimise the NFs' concentration. Optimized C-dot, MXene, and hybrid NFs were used for experimentation in the PV/T system. Energy, exergy, and enviro-economic analysis was conducted on the PV/T system with each HTFs. The results show that the thermal efficiency of PV/T was enhanced by 5.39, 3.87, and 9.45 % with C-dot, MXene and hybrid NFs, respectively. Hottel-Whillier-Bliss (HWB) analysis was performed on the collector from the generated experimental data. The analysis states that at zero heat loss conditions, the thermal efficiency of the PV/T was enhanced by 5.4 % with the hybrid NF. The maximum CO2 emission from PV/T with C-dot, MXene, and hybrid NFs, were calculated to be around 2.024, 1.979, and 1.931 kgCO2/day, respectively. Emission cost reduction analysis states that the hybrid NF achieved the highest reduction of 0.02 $/day which was a considerable decrement of 13.5 % over the water-based PV/T system.