Improving the Efficiency of Wind Power System by Using Natural Convection Flows

In this paper a numerical study of natural convection in a two dimensional convergent channel, with or without rectangular block, is carried out. The block is placed at the channel outlet and its thermal conductivity is set equal to that of air. One of channel planes is heated at constant temperature T-H. The other one is maintained cold at T-C < T-H. The governing equations are solved using a finite volume method and the SIMLEC algorithm for the velocity-pressure coupling is used. Special emphasis is given to detail the effect of the block size and Rayleigh number on the dynamics of velocity, heat transfer and the debit generated by natural convection. Results are given for the following control parameters, 10(4) <= Ra <= 10(6), Pr=0.71. The inlet and outlet opening diameters are, respectively, C-1 = c(1)/h=0.2 and C-2 = c(2)/h=0.1 : Three values of the block height are considered: B = b/h=0.1, 0.14 and 0.2. These results show that the heat transfer and the mass flow rate variations with Ra are similar to those occurring in the case of the vertical isothermal parallel planes. The effect of the block height on the flow structure and heat transfer is negligible.