Thermal Design of Uniformly Heated Vertical Convergent Channels in Natural Convection in Air

In this paper, design charts for the evaluation of thermal parameters for natural convection in air in a vertical convergent channel are proposed. In the thermal analysis of natural convection in a convergent channel, the parameters that play an important role are: the heat flux, maximum wall temperatures and geometrical parameters such as the length of the heated walls, the minimum and maximum channel sections. A simple numerical procedure to obtain the thermal design charts is presented. Results are carried out for symmetrically heated channels with walls at uniform heat flux. Some simple examples are given to show the use of the charts. The proposed charts are obtained from data resulting from numerical investigation in the following parameter ranges: angles of convergence not greater than 10 deg, surface emissivity between 0.10 and 0.90, 30 ≤ (q_c + q_r)≤ 220 W/m², 2.0 ≤ L/b_max ≤ 60 and 0.030 ≤ b_min/b_max ≤ 1.0.