Abstract
Hot water storage tank with heat pump draws a lot of attention nowadays due to its high performance. In Japan, reheat run for bath is commonly used, and so water having middle temperature return back to the storage tank and affect the temperature stratification. In order to maintain hot water at the upper region, return water is injected into the middle of the tank, horizontally. On a process of designing a hot water storage tank, it is necessary to simulate temperature distribution, since test run itself is time consuming process. Investigation was carried out on the effect of horizontal jet injection having positive or negative buoyancy to water in a tank. Visualization was carried out using tracer particles. Momentum effect is stronger than that of buoyancy, vortex was observed near the opposite wall. Hence, the condition to consider the existence of the opposite wall as negligible was obtained. One dimensional model with uniformly distributed injection was proposed. Within the condition, numerical calculations using the model were compared with the experimental results, and unsteady state temperature distribution showed a good agreement.
