The device performance of the new design of wire mesh packed double-pass solar air heaters with attaching wire mesh under external recycle was investigated experimentally and theoretically. The improvement of device performance of wire mesh packed solar air heaters with different flow patterns is represented graphically and compared, including the single-pass, flat-plate double-pass with recycle and wire mesh packed double-pass with recycle. Heat transfer improvement is considerably obtained by employing such a recyclic double-pass with wire mesh packed, instead of using the flat-plate single-pass operation. The wire mesh packed double-pass device introduced in this study was proposed for aiming to strengthen the convective heat transfer coefficient for air flowing through the wire mesh packed bed, and to determine the optimal design on an economic consideration in terms of both heat transfer efficiency improvement and power consumption increment. The effect of recycle ratio on the heat transfer efficiency enhancement as well as the power consumption increment has been also delineated.
