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- 2018
矩形通道内蒸汽射流凝结换热面积的实验研究
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Abstract:
针对超声速气液两相流升压装置内高速蒸汽射流凝结现象,在蒸汽质量流率为200～600 kg？m－2？s－1、入口过冷水质量流率为4～18 t？m－2？s－1、入口过冷水温度为20～50℃的条件下,使用矩形截面蒸汽喷嘴和混合腔进行了可视化实验研究;采用热平衡相变模型计算了蒸汽射流凝结的换热面积,给出了换热面积随汽水参数的变化规律,并建立了预测归一化换热面积的实验关联式。研究结果表明:蒸汽喷嘴截面形状对射流凝结流场结构影响不大,气液两相区是蒸汽凝结的主要区域,蒸汽在气液两相区内以小气泡的形式与过冷水完成能量交换,换热面积随蒸汽质量流率和过冷水温度的增加而增加,随过冷水质量流率的增加而减小。实验中测得的换热面积在2.4×10－3～7.8×10－3 m2之间,换热面积实验关联式预测值与实验值的误差在±10％以内。本文研究结果对超声速气液两相流升压装置的优化设计和安全运行具有重要意义。
To investigate the steam jet condensation phenomenon in a two？？phase flow steam injector, a visualized experimental study in a rectangular mix chamber was carried out when the steam mass flux, water mass flux and water temperature were in the range of 200？？600 kg？m－2？s－1, 4？？18 t？m－2？s－1 and 20？？50℃, respectively. With a thermal equilibrium phase change model, the interfacial heat transfer area of steam jet condensation was calculated, and its change with the above parameters was investigated. Besides, an experimental correlation for predicting the dimensionless heat transfer area was established. The results indicate that the cross section shape of the steam nozzle has little influence on the structure of condensation flow field, and the two？？phase region in the flow field is the dominant area for steam condensation, where the steam phase transfers energy to subcooled water in the form of steam bubbles. The interfacial heat transfer area increases with the steam mass flux and water temperature, while decreases with the water mass flux, in the range of 2.4×10－3？？7？？8×10－3 m2. The errors of heat transfer area between the prediction from the correlation and experimental values are within ±10％. This study may provide a reference for design and safe operation of two？？phase flow steam injectors
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