Dust accumulation effect of glazing cover inner surface on the performance of transpired solar air collector

Relative to the easier removal of accumulated dust on the outside of solar devices, it's very difficult to clean up the internal dust particles. So, from the aspect of ensuring the long-term high-performance operation of transpired solar air collector, the paper investigates the tilt angle effects on the dust accumulation amount of glazing cover inner surface and associated reduction in collector performance. In process, various forces causing the dust particles move to the inner surface and collide with them and then deposit, are thoroughly analyzed. To estimate the heat collected loss induced by dust, an empirical relationship predicting the light transmittance reduction has been explored, valid for relatively small dust accumulation amount. The results indicate that mainly under the force of gravity, the dust deposition density on the inner surface increases with the tilt angle. However, in view of the difference of solar irradiance in five tilt angles at the same time, it is not that the higher the dust deposition density, the lower the temperature rise from collector inlet to outlet. Hence, the tilt angle should be determined based on the comprehensive evaluation of the resulting changes of solar irradiance and dust accumulation amount, combined with local meteorological conditions.