The device performance improvement of the new design of recycling double-pass solar air collectors with welding W-ribs on the absorber plate was investigated experimentally and theoretically.
Applications of welding W-ribs on the absorber plate and performing recycling operations to the solar air collector were proposed to strengthen the convective heat-transfer coefficient due to the turbulence enhancement. A significant improvement of device performance on recycling W-ribs double-pass solar air collectors was achieved with the air flowing over and under the W-ribs absorbing plate, which effectively enhances the heat transfer efficiency compared to various designs such as the single-pass, flat-plate double-pass and double-pass wire mesh packed operations. The recycling W-ribs double-pass device introduced in this study was proposed for aiming to determine the optimal operating condition on an economic consideration in terms of both heat transfer efficiency improvement and power consumption increment. The fairly good agreement between theoretical predictions and experimental measurements was achieved.