Transient boiling and pressure recovery in a vacuum vessel during cooling of a high temperature body with an impinging jet

采用冲击射流对300℃高温圆柱体在真空容器中冷却后的瞬态传热进行了实验研究。实验条件为初始压力500 ~ 1000 Pa，射流速度1 ~ 15 m/s，射流直径1 ~ 3mm，射流温度10 ~ 90ºC，试验液为水。以铜、黄铜和钢为试验材料，考察了不同热性能对瞬态冷却的影响。实验结果如下：1；压力回收和传热特征分为三个区域：A区：压力回收以过热液体的冲洗蒸发为主。这个区域在短时间内结束。高温体的传热速率受到限制，导致射流的液体蒸发很少。区域B：压力恢复受沸腾产生的蒸气量的影响…更多关于高温盘。沸腾区随时间向圆盘表面外缘移动。区域C：压力恢复到相应的状态并保持恒定，在此期间，表面的传热变成强制对流，只有2。压力恢复和传热速率受到测试材料的强烈影响，因为高温表面开始润湿的时间取决于热性能。材料的热学性质决定了材料表面的传热速率。虽然地表与测点之间存在时间差，因此不能准确预测，但本文提出了一种利用冷却过程中瞬态温度估算地表热流密度的计算方法。虽然沸腾面积的移动与换热速率之间存在时滞，但两者之间的关系是明确的。建立了用换热率预测冷却过程压力恢复的模型，结果表明预测值与实验值吻合较好。少

An experimental study has been made on transient heat transfer during cooling of a high temperature (300ﾟC) cylindrical body mounted in a vacuum vessel with an impinging jet and then recovery of pressure in the vessel. The experiment was carried out for initial pressure of 500 to 1000 Pa, jet velocity of 1 to 15 m/s, jet diameter of 1 to 3 mm, and jet temperature of 10 to 90ﾟC using water as test liquid. Copper, brass and steel are used as test material in order to check effect of different thermal properties on the transient cooling. The following results are obtained :1. Characteristics of pressure recovery and heat transfer are categorized in to three regions asRegion A : The pressure recovery is dominated by flush evaporation of superheated liquid. This region finishes at a short time. The heat transfer rate from high temperature body is limited resulting into little evaporation of liquid of jet.Region B : The pressure recovery is influenced by amount of vapor generated by boiling … More on high temperature disk. Boiling area moves toward outer edge of disk surface with time.Region C : The pressure recovers to a corresponding state and is kept constant during which heat transfer from the surface becomes forced convective, only.2. The pressure recovery and heat transfer rate are strongly influenced by test material since the time at which wetting of the high temperature surface starts depends on thermal properties. The heat transfer rate from the surface would be controlled by thermal properties of material.3. A computation procedure is developed to estimate surface heat flux from transient temperature during cooling, although a time lag exist between surface and measuring points and then is not predicted accurate.4. A relationship between movement of boiling area and heat transfer rate is made clear, although a time lag between them exists.5. A model to predict pressure recovery from heat transfer rate during cooling is developed, showing that the value predicted is in good agreement with experimental one. Less