| 摘要: |
| 本文对R134a在水平微细管内的流动沸腾进行了实验研究。实验测试段选用了内径为1 mm、2 mm、3 mm共3种不同的水平光滑不锈钢管，实验的饱和温度为5~30 ℃，热流密度为2~70 kW/m2，流量范围为200~1500 kg/(m2s)。实验结果表明：相同条件下，干涸前2 mm管较3 mm管换热系数平均增幅为11.6%，1 mm管较2 mm管换热增幅为26.3%，1 mm管径换热系数比3 mm管径平均增大40.8%。随着管径的减小，换热系数在更低的干度开始减小，质量流速和强制对流蒸发作用对换热系数的影响变小，热流密度的影响依然显著；塞状流和弹状流区域减小，泡状流和环状流区域增大。 |
| 关键词: R134a 微细管 流动沸腾 干涸 换热系数 |
| DOI： |
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| 基金项目: |
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| Experimental Studies on Flow Boiling of R134a in Horizontal Small Tubes |
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Ding Yang1, Liu Jianhua1, Ye Fangping2, Jiang Linlin1, E Xiaoxue1, Wu Hao1
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| (1.School of Energy and Power Engineering, University of Shanghai for Science and Technology;2.Zhejiang Xinjing Air Conditioning Equipment Co., Ltd.) |
| Abstract: |
| Experimental investigation on the flow boiling of R134a in horizontal mini-channels was carried out in this study. The test sections are three different horizontal smooth stainless steel tubes with inner diameter of 1mm, 2mm and 3mm. The experiment was performed on the saturated temperatures ranging from 5 to 30 ℃, heat fluxes from 2 to 70 kW/m2 and mass fluxes from 200 to 1500 kg/(m2s). The results indicated that on the same conditions the pre-dryout heat transfer coefficients in 2-mm-ID tube increased 11.6% averagely than the 3-mm-ID tube, the coefficients in 1-mm-ID tube increased 26.3% averagely than the 2-mm-ID tube and the heat transfer coefficients in the 1-mm-ID tube were 40.8% greater in average than those in the 3-mm-ID tube. With decreasing tube diameter the coefficients started decreasing at lower vapor quality, the effect of mass flux and the contribution of forced convective evaporation on the local heat transfer coefficient decreased while the effect of heat flux was still strong in all three tubes, the zone of plug flow and slug flow decreased while the zone of bubbly flow and annular flow increased. |
| Key words: R134a mini-channel flow boiling dryout heat transfer coefficient |
