HEAT TRANSFER AT NATURAL CONVECTION OF VAN DER WAALS GAS

Abstract

This paper focuses on a study of natural convection in a Van der Waals gas over a vertical heated plate. An approximate analytical solution of the problem was obtained using an integral method for momentum and energy equations. A simplified form of the van der Waals equation for real gases enabled estimating the effects of the dimensionless van der Waals parameters on the normalized heat transfer coefficient. The effects of the dimensionless Waa and Wab numbers on the normalized Nusselt number in the real gas compared to the ideal gas were estimated. The analysis of the calculation results showed that, with an increase in the Waa number (which characterizes the additional pressure in the real gas), the normalized Nusselt number increases. The effect of additional volume, which  shows in an increase in the Wab number, causes a deterioration in the conditions  interaction between gas molecules and the wall. This is accompanied by a decrease in the Archimedes force and flow rate in the boundary layer, which leads to a weakening of heat transfer in comparison with an ideal gas.