基于液化天然气低温冷藏车的相变蓄冷实验

Experimen on cold storage with phase change based on LNG low temperature refrigerated vehicle

针对以水为相变工质通过铜质圆管壁与低温氮气换热发生固液相变问题,通过测温和可视化测量手段模拟研究固液相变贮存LNG冷量过程,获得管内低温气体、管外液相区温度分布及冰层图相,分析了管内换热和液相区自然对流综合影响下的冰层变化和分布特性,结果表明:该换热问题具有典型的变壁温变热流密度的热边界条件;冰层厚度在有限时间内近似线性增长,且沿管长锥状分布、冰层锥度随时间呈对数增长趋势;由于液相区水的密度反转效应使自然对流主流向发生改变,导致上下壁面冰层厚度发生反转。

The liquefied natural gas （LNG） cold energy recovery and storage process was simulated with water as a kind of phase change material outside the cupper tube, which occurred phase transformation when exchanging heat with the cryogenic nitrogen gas in the tube. Temperatures of cryogenic gas in tube and water outside were measured and ice profiles were recorded with optical technology. The characteristics of ice layer growth and distribution affected by internal convection heat transfer and natural convection in bulk region was analyzed. The results show that there is a typical varied wall temperature and varied heat flux thermal boundary for the solidification outside the tube, the ice formed outside the tube surface grows quasi-linearly during the experiment progress, the phase interface along the tube displays the conical shape whose tapering ratio increases as a logarithmic function of freezing time. Moreover, the ice thickness is also affected by bulk region transient natural convection subjected to water density inversion.