Experimental Study On Natural Convection Of Cold Water Near The Maximum Density In Horizontal Annulus And Square Cavity

Ice-storage technology is one kind of important technology with saving energy, and plays an important role in the power grid's measures of moving peak and valley. It can effectively relieve the electrical pressure in peak, and makes the power resources obtain the reasonable allocation, and at the same time, it can save energy effectively.Based on the phenomena of natural convection in ice-storage system with internal melt ice-on-coil when the ice begins to melt, we conduct experimental research. Through the experimental research, we discuss the basic law of natural convective heat transfer process and the influence factors on natural convection in horizontal annulus and square cavity when the cold water is near the maximum density. These can improve ice-on-coil technology. In the experiments, the temperature differences between the inner and outer walls range from 1 to 10℃, and the temperature at the outer wall is maintained near 0℃. The results show that the average heat transfer coefficient at the inner wall in horizontal concentric and eccentric annulus increases with the increase of the annulus width (the radius ratio), and with the increase of the width diameter ratio in horizontal square cavity. When the temperature difference is far less than 4K, the average heat transfer coefficient is big because of the influence of heat conduction. When the temperature difference is bellow and near 4K, the average heat transfer coefficient increases with the increase of the temperature difference. When the temperature difference is between 4K and 8K, it decreases with the increase of the temperature difference. When the temperature difference is above 8K, it increases with the increase of the temperature difference. Additionally, the average heat transfer coefficient at inner wall in horizontal and eccentric annulus is related to eccentricity, and it increases with the increase of the eccentricity in the range of experiments. Finally, the experimental formula of heat transfer on the inner wall is obtained by using Eviews tools.