Condensation heat transfer of mixed R134a/R125 outside horizontal tubes

ZHANG Dingcai; DU Jiadi; JI Wentao; ZHANG Zhen; ZHU Chunjie; HE Yaling; TAO Wenquan

doi:10.3969/j.issn.0438-1157.2014.z1.019

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Condensation heat transfer of mixed R134a/R125 outside horizontal tubes

更新时间：2025-12-10

- Condensation heat transfer of mixed R134a/R125 outside horizontal tubes
- CIESC Journal Issue S1, Pages: 119-124(2014)
- 作者机构：
  
  1. 中原工学院能源与环境学院, 河南省高等学校供热空调重点学科开放实验室,河南,郑州,450007
  2. 西安交通大学能源与动力工程学院, 热流科学与工程教育部重点实验室,陕西,西安,710049
- 作者简介：
- 基金信息：
- DOI：10.3969/j.issn.0438-1157.2014.z1.019
  CLC： K124
- Online First：30 May 2014，
  
  Published：30 May 2014
- 稿件说明：
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ZHANG Dingcai, DU Jiadi, JI Wentao, et al. Condensation heat transfer of mixed R134a/R125 outside horizontal tubes[J]. CIESC Journal, 2014, (S1): 119-124.
DOI：

ZHANG Dingcai, DU Jiadi, JI Wentao, et al. Condensation heat transfer of mixed R134a/R125 outside horizontal tubes[J]. CIESC Journal, 2014, (S1): 119-124. DOI： 10.3969/j.issn.0438-1157.2014.z1.019.

摘要

对纯工质R134a以及R134a/R125在三种不同组成比例下的混合工质，在光管和相同肋密度的二维及三维强化管外进行凝结换热试验研究。结果表明：R134a在光管外凝结表面传热系数与Nusselt数理论值的相对偏差均在±10%以内，R134a在光管及强化管外凝结表面传热系数变化趋势与Nusselt数理论解相一致。与纯R134a相比，含R125的混合工质管外凝结表面传热系数均所有下降；对于光管，含R125的混合工质管外凝结表面传热系数随壁面温差的增大而下降，但对于强化管，含6%及以上的R125混合工质，其凝结表面传热系数随壁面温差的增大而增大，有接近纯R134a凝结表面传热系数的趋势，表明混合工质凝结换热热阻分布与纯工质有较大差异。相同组分的工质，三维强化管凝结表面传热系数均高于二维强化管，二维强化管亦明显高于光管，在壁面温差为8 K时，强化管HT-3D、HT-2D相对于光管的传热强化倍率分别为9.83和7.85。

Abstract

Experimental studies of film condensation of R134a and mixed R134a/R125 at three different concentrations have been conducted on three tubes

one is smooth tube

the others are two-dimensional and three-dimensional enhanced tubes at the same fin density. The results indicate that the predicted condensation heat transfer coefficients of R134a on smooth tube from Nusselt theory agree with the experimental data within ±10 percent. The condensation heat transfer coefficients of pure R134a are consistent with Nusselt theoretical trend for smooth and enhanced tubes. Compared with pure R134a

the condensation heat transfer coefficients of mixed R134a/R125 are all decreased. For smooth tube

condensation heat transfer coefficient of mixed refrigerants decreased with the increase of temperature difference. But for enhanced tubes

condensation heat transfer coefficients increased with the increase of temperature difference

which is close to pure R134a at high temperature difference

the mixed refrigerant including 6 percent and more R125. Indicating that condensation heat transfer of mixed refrigerants is quite different with pure refrigerants. Condensation heat transfer coefficient of three-dimensional enhanced tube is higher than that of the two-dimensional tubes

and two-dimensional tube is significantly higher than that of smooth tube at the same working fluid. The condensation heat transfer enhancement factor of HT-3D

HT-2D are 9.83 and 7.85

respectively

which compared with smooth tube at the temperature difference 8 K.

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