The characteristics and visualization of critical heat flux of R-134a flowing in a vertical annular geometry with spacer grids
The characteristics and visualization of critical heat flux of R-134a flowing in a vertical annular geometry with spacer grids
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DOI：
10.1016/j.ijheatmasstransfer.2007.04.024
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发表时间：
2008
影响因子：
5.2
通讯作者：
K. Lee;I. Bang;Soon-Heung Chang
中科院分区：
文献类型：
--
作者：
K. Lee;I. Bang;Soon-Heung Chang
本文以新型制冷剂R-134 a为工质，在一个加热棒和四个定位格架的垂直环形通道内进行了临界热流密度（CHF）实验研究。实验在出口压力为11.6、13、16和20 bar，质量通量为100- 600 kg/m2 s，入口温度为25-40°C下进行。CHF数据的参数趋势与先前在水中的理解非常一致。通过与流动障碍物对CHF影响的对比分析，表明R-134 a可以作为模拟高温高压条件下水CHF的模拟流体，即使在环空几何条件下也是如此。对流动气泡行为的直接观察有助于加深对流动障碍物对流动沸腾传热影响的认识。
In the present paper, critical heat flux (CHF) experiments of forced convection boiling were performed to investigate the CHF characteristics of a vertical annular channel with one heated rod and four spacer grids for new refrigerant R-134a. The experiments were conducted under outlet pressure of 11.6, 13, 16 and 20bar, mass fluxes of 100–600kg/m2s, and inlet temperatures of 25–40°C. The parametric trend of the CHF data was well consistent with previous understanding in water. The comparison between the present results with effect of the flow obstacle enhancing CHF and water data in similar geometry shows R-134a can be a modeling fluid for simulating water CHF in high pressure and high temperature condition even for annular geometry. The direct observation of flowing bubble behaviors contributes to enhancing our understanding on the effect of flow obstacles for flow boiling heat transfer.