The thermal stratification characteristics affected by a novel equalizer in a dynamic hot water storage tank

The thermal storage that uses water as a medium is one of the key technologies in the field of solar energy. With the purpose of improving the thermal stratification performance of a thermal storage tank, this paper proposes a novel equalizer and compares the direct and three-layer orifice under an initial temperature of 70 degrees C and an inlet temperature of 10 degrees C. With regard to the changes in temperature with an increase of the dimensionless time, this paper analysed the impact of the inlet structure on the thermal stratification under different flow rates (1 L/min, 2 L/min, 3 L/min, 4 L/min, 5 L/min, and 6 L/min). The results show that the Richardson number and the Fill efficiency of the equalizer mode are larger than those of the other two modes and that the MIX number for the equalizer mode is smaller than those of the other two modes. When the flow rate was 6 L/min, the Richardson numbers for the three modes were 6, 4 x 10(4) and 4 x 10(6); the fill efficiencies were 0.53493, 0.58493 and 0.81405; and the MIX numbers were 0.53154, 0.30923 and 0.03971 (at a dimensionless time of 0.4). As the flow velocity increases, the fill efficiencies of the direct and three-layer orifice modes gradually decrease from 0.71827 and 0.74001 at 1 L/min to 0.53493 and 0.58493 at 6 L/min, respectively. Comparatively, the Fill efficiency of the equalizer mode first increases from 0.77599 at 1 L/min to 0.85471 at 3 L/min and then decreases to 0.81405 at 6 L/min. These results demonstrate that the proposed equalizer can reduce the mixing process to improve thermal stratification. (c) 2017 Published by Elsevier Ltd.