Numerical analysis of mechanical ventilation solar air collector with internal baffles

• The internal flow and heat transfer characteristic of MV-SAC is numerically analyzed.
• The introduction of internal baffles can improve heat collecting efficiency.
• Convective heat transfer is dominated in the total heat loss.
• For a special scale MV-SAC, there exist an optimal number of baffles.
• This kind of MV-SAC could be applied in a wide range of area.

This paper aims to investigate a simple-structure mechanical ventilation solar air collector (MV-SAC) with internal baffles. A numerical model is developed to predict its internal flow and heat transfer characteristics. And a sample experimental system is built and tested for validation of the numerical model. The investigation results indicate that the introduction of baffles can strengthen the convective heat transfer process and lessen the radiation heat loss, which contributes to efficiency improvement. But the presence of baffles causes strong flow separation which results in flow loss to some extent. The convective heat loss of the top cover plate is dominative in the total heat loss. The influence of baffle number, the thickness of air gap, the number of top glass cover and the operating conditions on the collector performance is also analyzed, and the results show that as for a specific scale collector, there exists an optimal baffle number, for this case the number is three. The operating parameters such as the surrounding temperature, solar radiation intensity have significant influence on the temperature rise but have little influence on collector efficiency, which indicates that this kind of solar air collector could be applied in a wide range of geographical latitude.