Dust effect on the optical-thermal properties of absorber plate in a transpired solar air collector

The extent to which the accumulation of dust inside the collector has the capacity to influence its performance is generally overlooked. The purpose of this study therefore is to provide an understanding of the impact of dust specifically on the absorptivity and emissivity of absorber plate. Characteristics of dust deposition on its surface and associated reductions in absorptivity have been experimentally investigated in Tianjin of China. An empirical correlation is thus proposed and verified to predict the variation of absorptivity with respect to dust accumulation. Then the dusty heat transfer model has been used to estimate the collector performance drop in comparison with a similar clean one operating under the same conditions. It is concluded that the outlet temperature is largely influenced. The maximum value of efficiency drop over test periods is found to be 19.23%. Additionally, the effect of changes in absorber emissivity due to dust on the collector performance has also been studied, which is found to be so small that it can be ignored. The results of this work would improve the predictive capability of current collector simulation model.