摘要
随着节能减排的大力推广,管外沸腾强化传热技术得到了广泛的研究和发展。设计建立了水平双侧强化管管外沸腾试验系统,以R134a为循环工质试验研究了不同热通量工况下,蒸发温度对正反齿压花齿型三维肋管池沸腾换热特性影响,并结合试验结果分析探讨了其理论描述方法。结果表明:蒸发传热系数随蒸发温度变化趋势线的斜率随热通量呈现非线性变化;在同一蒸发温度下,管表面传热系数均随热通量单调递增,但增长率随热通量增加而逐步降低;回归分析获得不同热通量下蒸发温度对正反齿压花齿型蒸发管表面传热系数影响的统一表达式;等热通量工况强化传热因子在热通量超过10 k W·m^(-2)后升至2以上,在热通量接近20 k W·m^(-2)时达到极大值2.588,但在热通量接近5 k W·m^(-2)时接近1;蒸发温度及其与热通量合同对正反齿压花齿型蒸发管表面传热系数的作用机理与理论描述方法有待进一步深入研究。
Under a promotion of energy conservation and emission reduction, efforts on research and development of the technologies related to boiling heat transfer enhancement of outer tube have been conducted extensively. In this article, a testing system for boiling heat transfer outside the horizontal double-side enhanced tubes was established. Using R134 a as a cyclic working medium, the effect of evaporation temperature on the characteristics of boiling heat transfer in three-dimensional ribbed and embossing finned tube under conditions of varied heat flux was investigated, on basis of which theoretical descriptive method was discussed. It showed that, the curve slope of evaporation heat transfer coefficient as a function of evaporation temperature is non-linearly related to the heat flux. At the same evaporation temperature, it shows a monotonic increase in the heat transfer coefficient on tube surface with the heat flux, of which the slope gradually decreases with the heat flux. By means of regression analysis, an unified formula for the heat transfer coefficient on ribbed and embossing finned tube surface as a function of evaporation temperature under conditions of varied heat flux was achieved. Under operation condition of the same heat flux, the factor of heat transfer enhancement approaches 1, exceeds 2, and reaches the maximum 2.588 at 5, 10 and 20 k W·m^（-2） of heat flux, respectively. The mechanism and theoretic description of the heat transfer coefficient on ribbed and embossing finned tube surface as functions of evaporation temperature and heat flux, need to be further studied.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2016年第6期2230-2238,共9页
CIESC Journal
基金
国家自然科学基金项目(51578102)
中央高校基本科研业务费专项(DUT14ZD210
DUT15RC(4)24)~~
关键词
强化管
沸腾
蒸发温度
水平管
传热系数
enhanced tube
boiling
evaporation temperature
horizontal tube
heat transfer coefficient
