真空条件下蒸汽横掠水平降膜管束的流动阻力

Steam flow resistance across horizontal tube bundle under vacuum condition

建立了蒸汽横掠带有液体降膜流动的水平管束流动阻力实验台,对影响流动阻力的因素与规律进行了实验研究。实验在绝对压力为12～31kPa的真空条件下进行,对应的水蒸气饱和温度为50～70℃,模拟了大型海水淡化装置中水平管降膜蒸发器的流动过程。实验结果显示,蒸汽掠过带有降膜流动的水平管束的压降远大于蒸汽横掠水平管束的流动阻力,流动阻力系数不仅与蒸汽流动Reynolds数有关,还与液体在水平管上降膜流动的Reynolds数有很大关联。提出了正三角形排列管束的蒸汽横掠降膜流动管束的阻力关系式。

An experiment investigation of steam flow resistance across horizontal falling film tube bundle was carried out. Experiments were performed to simulate the flow process in a large horizontal falling film evaporator of MED desalination plant under the pressure from 12 kPa to 31 kPa and at the corresponding saturated steam temperature from 50℃ to 70℃ respectively. The results indicated that pressure drop of steam flowing across tube bundle with falling film was far greater than that through a plain tube bundle. Pressure drop coefficient not only was affected by vapor Reynolds number but also changed significantly with spray Reynolds number. From the experimental results a flow resistance correlation for steam flowing across horizontal tube bundle with falling film was proposed.