The airflow pattern and convective heat transfer mechanism in glass-free evaporative solar collectors (UTCs) integrated with photovoltaic thermal systems are critical to their performance. Computational fluid dynamics (CFD) simulations can be a valuable tool for designing and analyzing these hybrid building-integrated solar systems, and recent advances in CFD methods and turbulence models offer great potential to improve prediction accuracy. In this study, a three-dimensional steady-state Reynolds averaged Navier-Stokes (RANS) CFD simulation was performed and the performance of five turbulent closure models was evaluated, which may be applicable to the modeling of UTC in terms of accuracy and computational cost. These models include four two-way models (standard k-ε, the renormalization group method k-ε, achievable k-ε and shear stress transport k-ω) and a Reynolds stress model. Compiled by Chen Jiaoyun
Planar UTC under the condition of free flow close to flow and ripple UTC under the condition of planar wall jet are considered. The predicted air velocity, air temperature, and turbulent energy were compared with experimental data in the literature and with experimental data obtained in solar simulators using specially designed full-scale experimental setups. The results show that although the Reynolds stress model can provide more detailed flow characteristics at a higher computational cost than other models, it does not necessarily achieve better performance. Among the two-way models, the renormalization group method k-ε has the best overall performance in both cases, while the standard k-ε and shear stress transport k-ω models can also provide acceptable prediction accuracy. Using the CFD model developed in this study, a BIPV/T system with two PV panel arrangements in UTC with the same coverage area was studied. The study found that for the case under consideration, the integration of UTCs in the BIPV/T system resulted in a 1.2% increase in electrical efficiency.
