卧式螺旋管内过冷沸腾换热特性实验研究

第35卷第11期中国电机工程学报V ol.35 No.11 Jun. 5, 2015 2788 2015年6月5日Proceedings of the CSEE ©2015 Chin.Soc.for Elec.Eng. DOI：10.13334/j.0258-8013.pcsee.2015.11.017 文章编号：0258-8013 (2015) 11-2788-08 中图分类号：TK121

卧式螺旋管内过冷沸腾换热特性实验研究

孔令健，韩吉田，陈常念，逯国强，冀翠莲

(山东大学能源与动力工程学院，山东省济南市 250061)

An Experimental Investigation on Subcooled Boiling Heat Transfer

in a Horizontal Helical Coil

KONG Lingjian, HAN Jitian, CHEN Changnian, LU Guoqiang, JI Cuilian (School of Energy and Power Engineering, Shandong University, Jinan 250061, Shandong Province, China)

ABSTRACT: The subcooled boiling heat transfer of R134a in a helical tube was experimentally investigated. The experiments were carried out at pressure ranging from 0.41 to 0.63MPa, subcooled from 6 to12℃, heat flux from 0.11 to 10.9 kW⋅m−2 and mass flux from 147 to 249kg⋅m−2⋅s−1. The wall temperature distribution of a horizontal helical coil was analyzed on the conditions of subcooled boiling. The experimental results indicate that the wall temperature distributions of the cross sections are non-uniform. The location of the cross section was found to has a significant impact on the transition from partial to fully developed subcooled flow boiling. The effects of the boiling heat flux, refrigerant mass flux, system pressure and inlet subcooling of R-134a on the coefficient of subcooled boiling heat transfer were explored in detail. The R134a subcooled flow boiling heat transfer coefficient increases with an increase in heat flux and system pressure. However, raising the inlet subcooling can cause a reduction on boiling heat transfer coefficient. Besides, the mass flux exhibits rather slight effects on heat transfer coefficient. The correlation of subcooled boiling heat transfer coefficient in horizontal helical coil was developed on the basis of regression analysis of experimental data.

KEY WORDS: horizontal helical coil; subcooled boiling; wall temperature; heat transfer coefficient; correlation

摘要：在系统压力p=0.41~0.63MPa，过冷度ΔT sub=6~12℃，热流密度q=0.11~10.90kW⋅m−2，质量流量G=147~249kg⋅m−2⋅s−1的条件下，对卧式螺旋管内R134a过冷流动沸腾的换热特性进行了实验研究。分析过冷沸腾条件下螺旋管不同截面上的壁温分布表明：截面周向壁温呈现不均匀分布；螺旋管的截面位置对部分过冷沸腾向充分发展过冷沸腾的转变产生了很大影响。分析了各实验参数对充分发展过冷沸腾

基金项目：国家自然科学基金项目(51076084)。

Project Supported by National Natural Science Foundation of China (51076084). 换热系数的影响趋势：随着热流密度、系统压力的增大换热系数不断增大；但是，当入口过冷度增大时换热系数却在减小；质量流量对换热系数的影响并不明显。对实验数据进行回归分析，发展了适用于卧式螺旋管内充分发展过冷沸腾换热系数的关联式。

关键词：卧式螺旋管；过冷沸腾；壁面温度；换热系数；关联式

0 引言

过冷沸腾作为一种高效的换热手段，在核反应堆、发动机冷却水套、核潜艇动力系统以及超导体线圈冷却等方面有着广泛的应用[1-4]。如我国自行设计研制的国际首个全超导托卡马克装置(EAST装置)，EAST 第一壁[5]中直接受到等离子体高温作用部件上的热流密度高达4MW⋅m−2。已有的冷却方法是将冷却水管与热沉通过钎焊的方法联接在一起，通过水的单相对流进行换热，但是随着运行参数的提高，单相换热已很难满足换热要求，必须采用过冷沸腾换热方式。

过冷流动沸腾传热是汽液两相流动与相变传热这两种复杂物理现象的耦合[6]。与饱和沸腾不同的是：过冷沸腾整体处于热力学不平衡状态。此时由壁面进入的热量不完全用于气液相变，部分热量将用于流体温度的提升。因此，研究过冷沸腾的特性与机理具有重要的意义。国内外学者对过冷沸腾已经进行了大量的研究[7-11]。在早期的研究中，Bergles[7]通过实验与理论分析计算相结合的方法对沸腾起始点和传热状况进行了研究，Levy[8]则通过理论分析建立了过冷沸腾中气相体积分数的计算模型，并通过实验数据验证了模型的准确性。Hong Gang[9]等通过实验对矩形窄通道在静态和起伏状态下过冷沸腾起始点进行了研究。研究结果表明：