| Abstract: | An experimental study was executed using a small model pond to examine the erosion phenomenon on the gradient zone of a solar pond. By means of observing the flow pattern of the heat reserve zone, it was made clear that the erosion was caused by naturally occurring convection, which is based on the vertical temperature difference in the heat reserve zone. In other words, the ruling factor in erosion is the vertical temperature difference in the heat reserve zone. With regards to a real solar pond, a policy was proposed which suppresses erosion velocity by controlling the pond's operating conditions while keeping the temperature gradient of the non-convection zone (NCZ) as large as possible and making the vertical temperature difference in the heat reserve zone small. On analysis, the rational modification was effected by the Grashof number Gr, which is a dimensionless number and shows the influence of the flotage on the speed field and the temperature field. As a result, it was found that the modified dimensionless Grashof number explains the erosion velocity of the gradient zone well. Moreover, the function of the correlation between the erosion velocity and the modified Grashof number was obtained by regression calculation and could estimate the erosion condition of the gradient zone quantitatively. |
