Numerical analysis and design of a novel solar photovoltaic thermal system using finned cooling channel structures embedded with air/TiO2-water nano bi-fluid

The suboptimal cooling efficiency of solar PV panels stands as a significant bottleneck affecting their electrical performance. The concept of a bi-fluid photovoltaic thermal (BFPVT) system based on the usage of double exchangers cooling with simultaneously using two types of coolants recently offers a promising strategy for the multiplication of the electrical and thermal performances of PVT systems. Hence, this study presents a detailed 3D numerical investigation and comparative performance analysis on a BFPVT based on the simultaneous cooling with both natural air and water/TiO2 nanofluid under two structures of cooling channels (finned and non-finned configurations). A parametric analysis is conducted to assess the impact of varying concentrations of TiO2 nanoparticles (ranging from 0.0 to 1.0 %) to determine the optimal concentration of TiO2-water nanofluids that yield the highest cooling rates and thermal efficiency in BFPVT collectors. In addition, an energic analysis of the simulated BFPVT systems is developed to determine the average daily thermal efficiency and nano-bifluid temperature rise under the investigated configurations. The results indicated that as the concentration of TiO2-water nanofluid increases, both the water outlet temperature and air outlet temperature also rise, thus remarkably improve the cooling rates and thermal efficiency of the proposed BFPVT system. Moreover, it is optimistically revealed the BFPVT configuration with 1.0 % TiO2 nanoparticle concentration and eight parallel longitudinal fins outperformed the BFPVT performance amongst the investigated configurations. At these conditions, the peak hourly thermal efficiency of the air and TiO2-water BFPVT for the finned and non-finned configurations are estimated as 78.6 % and 70.8 %, respectively, at a continuous TiO2-water flow at a rate of 0.015 kg/s, along with a concurrent airflow. Moreover, the mean daily thermal efficiency is computed as 56.3 % and 50.4 % for the finned and non-finned configurations at the same optimal conditions.