Numerical Simulation On Natural Convection Of Water Near The Maximum Density In Horizontal Annulus

Natural convection is caused by the function of the temperature difference or the concentration difference of the liquid. Mounts of scholars are very interested in natural convection existing in nature. Commonly, densities of objects decrease linearly with the increasing of the temperature, namely Boussinesq supposing. However, density inversion point of water can influence natural convection, natural convection of water becomes complex and interesting.In order to understand the basic characteristics of the heat transfer of natural convection of water near the maximum density in horizontal annulus, two-dimensional numerical simulation has been done by finite volume method. The temperature of outer wall is maintained at 0℃, and the temperature of inner wall at (1-10)℃. The results show that for both concentric and eccentricity horizontal annulus in the range of calculation, heat transfer coefficient at inner wall decreases with the increasing of the width of annulus firstly, and then little increases. But it monotonously decreases with the increasing of inner radius. When the temperature difference bellow 4℃, heat transfer coefficient increases with the increasing of the temperature difference, and when the temperature difference exceeds 4℃, it decreases with the increasing of the temperature difference. Additionally, heat transfer coefficient of inner wall of eccentricity horizontal annulus is related to eccentricity. The results show that heat transfer coefficient of inner wall of eccentricity horizontal annulus increases with the increasing of eccentricity in the range of calculation. Finally, the formula of heat transfer of inner wall is obtained by the method of linear regression.