Numerical analysis on geometric and shape parameters of solar dual-catalytic Trombe wall performance

•The shapes of channel inlet and outlet of SDC-TW were modified.•Performance of SDC-TW was studied based on 2D numerical model.•Effects of channel height, channel width and modified shape parameter.•Purification ratios of photocatalysis and thermocatalysis in SDC-TW.•The optimal shape parameter corresponding to the best performance. As a typical multi-functional Trombe wall, solar dual-catalytic-Trombe wall (SDC-TW) incorporating photocatalytic and thermocatalytic technologies has received more attention recently. In this paper, a modified shape of channel inlet and outlet featured by Quadratic Bezier Curve was proposed to enhance the performance of SDC-TW. By solving a two-dimensional numerical model, the effects of channel height H, channel width W and modified shape parameter d on the thermal performance and air purification performance of SDC-TW under different solar radiation intensities I were investigated, as well as the purification ratios of photocatalysis and thermocatalysis in SDC-TW. The results show that, for SDC-TW with conventional shapes of channel inlet and outlet, thermal efficiency ηth is less affected by H, decreases with increasing W (when I exceeds 400 W/m2, the descending trend shows slight fluctuations), and climbs as I increases; while the air purification efficiency ηHCHO declines with the increase of H and I, and rises with the increase of W. Under the same conditions, bending the channel inlet and outlet can increase ηth, ηHCHO and ηtotal by up to 47.46%, 30.77% and 29.34%, respectively. Furthermore, the optimal value of d corresponding to the maximized ηth and ηtotal decreases as I grows whereas the optimal d corresponding to the maximized ηHCHO is 0.07 m under different I. With the increasing of I, the purification ratio of photocatalysis in SDC-TW decreases slightly.