Experimental study on natural convection of cold water near the maximum density in horizontal annulus

This paper conducts the experimental study on the natural convection characteristics of cold water near the maximum density in horizontal annulus with the fixed inner radius ri=14 mm and different width l=6~18 mm. The temperature at outer wall is maintained at 0C, and the temperature differences between the inner and outer walls range from 2 to 24C. The results show that the heat transfer coefficient at inner wall increases with the increase of the annulus width. When the temperature difference is bellow 4C or above 8C, the heat transfer coefficient increases with the increase of the temperature difference. When the temperature difference is between 4C and 8C, it decreases with the increase of the temperature difference. The formula of heat transfer at inner walls is obtained by using the method of linear regression.