The Effect of Heating Direction on Flow Boiling Heat Transfer of R134a in Micro- channels

分类： 动力与电气工程 >> 工程热物理学 提交时间： 2017-03-31 合作期刊: 《热科学学报》

XU Mingchen JIA Li DANG Chao PENG Qi

摘要： This paper presents effects of heating directions on heat transfer performance of R134a flow boiling in mi- cro-channel heat sink. The heat sink has 30 parallel rectangular channels with cross-sectional dimensions of 500m width 500m depth and 30mm length. The experimental operation condition ranges of the heat flux and the mass flux were 13.48 to 82.25 W/cm2 and 373.3 to 1244.4 kg/m2s respectively. The vapor quality ranged from 0.07 to 0.93. The heat transfer coefficients of top heating and bottom heating both were up to 25 kW/m2 K. Two dominate transfer mechanisms of nucleate boiling and convection boiling were observed according to boiling curves. The experimental results indicated that the heat transfer coefficient of bottom heating was 13.9% higher than top heating in low heat flux, while in high heat flux, the heat transfer coefficient of bottom heating was 9.9%.higher than the top heating, because bubbles were harder to divorce the heating wall. And a modified corre- lation was provided to predict heat transfer of top heating.

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