Flow Boiling Heat Transfer of R134a in Multi Microchannels
Flow Boiling Heat Transfer of R134a in Multi Microchannels
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DOI：
10.1016/j.ijheatmasstransfer.2017.03.057
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发表时间：
2017-07
影响因子：
5.2
通讯作者：
Ekhlas M. Fayyadh;M. Mahmoud;K. Sefiane;T. Karayiannis
中科院分区：
文献类型：
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作者：
Ekhlas M. Fayyadh;M. Mahmoud;K. Sefiane;T. Karayiannis
对R134a在多微通道热沉中的流动沸腾换热进行了实验研究。散热器由25个矩形微通道组成，标称尺寸为300微米宽，700微米深(dh=1420微米)，隔壁厚度200微米。散热器由无氧铜经数控加工制成，长20毫米，宽15毫米。这些实验是在6.5bar系统压力下进行的，覆盖了基于足迹区域的热通量范围11.46-403.1 kW/m2和质量通量50-300g/m2。采用高速相机在测量换热的同时捕捉流型。当热流密度逐渐增大时，观察到泡状流、弹状流和波状环状流三种流型。换热系数随热流密度的增加而增大，不存在质量流量效应。对现有相关性的评估表明，Mahmoud和Karayiannis(2013)和Cooper(1984)的相关性很好地预测了数据，与其他相关性相比，平均绝对误差不到20%。
Experiments were conducted to investigate flow boiling heat transfer of R134a in a multi microchannel heat sink. The heat sink consisted of 25 rectangular microchannels with nominal dimensions of 300 µm wide, 700 µm deep (Dh= 420 µm) and 200 µm separating wall thickness. The heat sink was made of oxygen free copper by CNC machining and was 20 mm long and 15 mm wide. The experiments were conducted at 6.5 bar system pressure and covered a footprint area-based heat flux range 11.46–403.1 kW/m2and mass flux range 50–300 kg/m2s. A high speed camera was used to capture the flow patterns simultaneously with heat transfer measurements. Three flow patterns were observed namely bubbly, slug and wavy-annular flow when the heat flux increased gradually. The heat transfer coefficient increased with heat flux and there was no mass flux effect. Assessing existing correlations indicated that the correlations of Mahmoud and Karayiannis (2013) and Cooper (1984) predict the data very well with a mean absolute error less than 20% compared to the other correlations.