Experimental Studies on Flow Boiling of R134a in Horizontal Small Tubes
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...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Journal of Refrigeration Magazines Agency Co., Ltd.
2015-01-01
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| Series: | Zhileng xuebao |
| Subjects: | |
| Online Access: | http://www.zhilengxuebao.com/thesisDetails#10.3969/j.issn.0253-4339.2015.01.090 |
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| Summary: | 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. |
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| ISSN: | 0253-4339 |