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OALib Journal期刊
ISSN: 2333-9721
费用：99美元
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空冷凝汽器逆流区扁平管内蒸汽流动凝结换热研究
, PP. 19-26
Keywords: 空冷凝汽器,扁平管,两相流,凝结,液膜,液池,冻结风险
Abstract:
针对空冷凝汽器扁平管内蒸汽逆流凝结流动换热过程,考虑逆流流动凝结汽液相间剪切力的反向作用,建立了包括扁平管平直壁面液膜发展段和底部圆弧段液池的理论分析模型，研究了凝结液的空间分布及凝结过程的流动换热特性。将该模型应用于冬季低温环境运行的5个典型工况,得出扁平管内凝结液膜厚度、凝结换热系数、压力损失等参数沿程的变化规律。结果表明,扁平管的平直壁面上仅形成了一层很薄的液膜,凝结液主要向扁平管圆弧底部聚集形成液池,液池厚度是偏平管周线方向最大的液膜厚度，其位置处于空气等冷却介质温度最低的区域,因而在冬季低温环境下面临着较大冻结风险；轴向沿程凝结传热系数随着轴向距离的增加而减小；在蒸汽主流流速高、壁面液膜很薄的进口区域,由于汽液相间剪切力过大引起了液膜回流。因此,可根据管内凝结液膜的空间分布,区分出冬季低温运行时不同区域发生冻结的难易程度。
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