摘要
针对一种双侧强化换热管,实验测试和分析了制冷工质R404A在管外凝结与水在管内对流的传热规律,采用"Wilson图解法"和"Gnielinski法"两种不同的方法对实验数据进行了处理。经理论分析和实验研究表明,Wilson图解法对于双侧强化换热管管内、管外表面传热系数实验容易产生较大误差,"Gnielinski法"是更合适的方法。实验得出了管内对流传热和管外凝结传热的计算关联式及传热的强化倍率。对于制冷剂R404A,在强化管外凝结的表面传热系数随着壁面过冷度的增加而增大,呈现出与纯工质光滑管外冷凝时不同的变化趋势。
Condensation of refrigerant R404A on doubly-enhanced tubes and convection heat transfer of water inside tube were measured and analyzed. The experimental data were processed by Wilson graphical method and Gnielinski method. Theoretical analysis and experi- mental studies show that the Gnielinski method is more appropriate to process the experiment data of doubly-enhanced tubes inside and outside surface heat transfer coefficients than the Wilson graphical method which will engender great error. The correlations of convective heat transfer inside tube and condensation heat transfer outside tube were obtained. The heat transfer enhancement ratios of inside and out side tube are 2.17 and 7.91, respectively. The condensation surface heat transfer coefficients of non-azeotropic refrigerant R404A on en- hanced tubes increase with increasing wall subcooling degree which present a different variation trend from pure refrigerants condensation on smooth tubes. That is mainly due to the vapour diffusion layer formed between the liquid film and the vapour bulk.
出处
《制冷学报》
CAS
CSCD
北大核心
2014年第1期92-97,共6页
Journal of Refrigeration
关键词
强化传热
冷凝传热
R404A
数据处理
heat transfer enhancement
condensation heat transfer
R404A
data processing
