Visualization of the phase change behavior of sodium acetate trihydrate for latent heat storage
Visualization of the phase change behavior of sodium acetate trihydrate for latent heat storage
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DOI：
10.1016/j.applthermaleng.2015.08.056
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发表时间：
2015-12
影响因子：
6.4
通讯作者：
Y. Ouchi;S. Someya;T. Munakata;Hiroshi Ito
中科院分区：
文献类型：
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作者：
Y. Ouchi;S. Someya;T. Munakata;Hiroshi Ito
潜热蓄热系统比显热蓄热系统具有更高的蓄热能力。三水合乙酸钠熔点为58℃，潜热大，适用于热水供应系统。采用温度敏感粒子（tsp）对三水合乙酸钠相变过程中的晶体生长速率、对流流场和温度场进行了定量可视化，实现了速度场和温度场的同步测量。通过PIV分析得到了速度场，同时通过tsp的强度衰减得到了温度场。固液多相流的显示温度随着晶体的生长而缓慢升高。在对流相变过程中，由于晶体呈针状且晶体之间存在液相，晶体周围温度低于熔化温度。在对流速度因凝固而迅速降低后，温度开始升高到熔点附近。在一定的过冷温度和三水合乙酸钠浓度条件下，浮力驱动对流发生。但在一定的浓度和过冷温度范围内，由于晶体生长速度过快，凝固完成得很快，对流不能充分展开。
A latent heat storage system has higher storage capacity than a sensible heat storage system. Sodium acetate trihydrate has large latent heat at its melting point of 58 °C, which is suitable for a hot-water supply system. The crystal growth rate, convective flow and temperature fields during the phase change of sodium acetate trihydrate were quantitatively visualized using PIV analysis with temperature sensitive particles (TSPs) which has enabled a simultaneous measurement of the velocity and temperature fields. The velocity field was obtained by the PIV analysis of TSPs and the temperature field was simultaneously visualized from the intensity decay of TSPs. The visualized temperature of the solid–liquid multiphase flow increased slowly as crystals grew. The temperature around the crystal was lower than the melting temperature during the phase change process with the convection because the crystal was needle-shaped and a liquid phase was also present between crystals. After the convective velocity rapidly decreased due to the solidification, the temperature started to increase to around the melting point. Buoyancy-driven convection occurred under certain conditions of supercooling temperature and concentration of sodium acetate trihydrate. However, convection could not be fully developed over a certain range of concentration and supercooling temperature because the crystal growth rate was too fast and solidification was completed quickly.