Abstract
Mixing characteristics in the hot water storage tank caused by supplying cold water were obtained and the method to predict t_0 (the switch over time to the process of extruding hot water) and H_0 (the height of the mixing region) was shown in previous paper. Still it is considered to be necessary to predict temperature distributions and their changes in a hot water tank for the design of a storage water heater. Temperature distribution changes in the rectangular hot water tank caused by supplying cold water has been measured. From the consideration of experimental results, the mixing region structure model has been proposed. The model consists of the idea that the mixing region is divided into two layers (mixing region I and II) and they change over three periods (forming, growing and developing periods). Before t_0, the whole mixing region is considered to be the mixing region II and the mixing region I is slightly formed in the bottom of the tank at t_0. The forming period ends at t_0. The temperature gradient at the mixing region II gets great and the mixing region I grows in the growing period. The growing period ends at the time the temperature gradient reaches maximum. In the developing period, the mixing region II doesn't change and the mixing region I increases it's height at the mean velocity in the horizontal cross section of the hot water tank. The method to predict temperature distribution has been shown. Fairy good agreements have been obtained between experimental and calculated results. It has turned out to be possible to predict temperature distribution in a hot water tank caused by supplying cold water with comparatively high accuracy.
