Hot Water Storage Tank, Thermal Behavior, CFD Analysis, Thermocline
Air Source Heat Pump Water Heater is an environmental –friendly technology with high efficiency. The thermal behavior of water in the storage tank has great importance for designing a more energy-saving control strategy. In this study, the time-dependent temperature distributions during typical transient processes including heating up and tapping processes are studied with a 3D CFD model of the water storage tank in a cyclic heat pump water heater. The simulated temperature profiles in the heating up period were in good agreement with the experimental results. Different initial conditions were tested in the heating up periods, and they had little influence on the final temperature profiles in a practical water tank. The influences of varied flow rates and supply water temperatures were studied in the tapping stages. The thermocline was shortened when the temperatures in the bottom were higher and the flow rates were larger. Finally, the possibility to calculate the flow rates from the temperature changes was discussed.