Thermal analysis of a bifacial vacuum-based solar thermal collector

In this study, thermal analysis of a vacuum-based bifacial solar thermal collector is conducted. This solar collector is expected to capture the solar radiation from both front and rear sides. One advantage of this collector is that it can work effectively in restricted positions where it should be installed in different positions such as vertically in narrow areas as road wind barriers. The effect of fluid inlet velocity and collector installation position, optimal tilted or vertical, on the performance of the proposed collector as one factor at a time is computationally evaluated. Further, response surface methodology is applied to evaluate the most significant factors affecting the operation of the collector and evaluating the interaction between different factors on the collector performance. The results showed that the proposed collector design still works effectively even for a vertical position of restricted areas. Further, the maximum absorber temperature is significantly increased by increasing the front radiation, water inlet temperature, and rear radiation ratio. Conversely, increasing the inlet velocity also significantly decreases the maximum absorber temperature. Furthermore, the effect of wind speed is statistically insignificant on the maximum absorber temperature. The heat loss from the proposed solar collector reduced by 78.5 % with increasing the coolant velocity from 5 mm/s to 30 mm/s.