TiO2/water-based photovoltaic thermal (PVT) collector: Novel theoretical approach

Nanofluids, which are new generation cooling fluids, have been found to improve the heat transfer coefficient and enhance the system performance in recent years. In this observation, TiO2/water nanofluid (with 0.5 wt% and 1 wt% TiO2) is used as a coolant to investigate the photovoltaic thermal (PVT) collector under solar radiation intensities of 500, 700 and 900 W/m(2) and mass flow rates ranging from 0.012 kg/s to 0.0255 kg/s. At high solar radiation, the thermal energy efficiency is high but is inversely proportional to the electrical energy efficiency due to the increment in PV surface temperature. The energy efficiency of 1 wt% TiO2 nanofluid-based PVT collector is 85%-89% compared with 60%-76% of water-based collector at 0.0255 kg/s. The improvement in exergy efficiency of 1.0 wt% TiO2 is 6.02% compared with that of water-based collector at the mass flow rate of 0.0255 kg/s. In addition, a new theoretical approach model is developed to compare the theoretical and experimental results of the TiO2/water nanofluid-based PVT collector. Considerably close agreement between the new theoretical approaches and experimental is obtained with an accuracy of 97.6%-99.2%. (C) 2019 Elsevier Ltd. All rights reserved.