摘要
在系统压力P=412~850 k Pa,过冷度?Tsub=4.7~15.0℃,热通量q"=0.11~10.90 k W·m^(-2),质量流量G=147.5~443.7 kg·m^(-2)·s-1的条件下,对立式和卧式螺旋管内R134a过冷流动沸腾起始点特性进行了实验研究。研究结果表明:当实验系统参数相同时,立式和卧式螺旋管内过冷沸腾起始点的热通量基本相同,但是立式螺旋管内过冷沸腾起始点壁面过热度小于卧式螺旋管;过冷沸腾起始点的热通量、壁面过热度随着过冷度和质量流量的增大而增大,但随着压力、螺旋直径的增大而减小。通过无量纲分析对实验数据进行非线性拟合,发展了适用于螺旋管过冷沸腾起始点的关联式。
An experimental study has been carried out to investigate the onset of nucleate boiling（ONB） characteristics of R134 a in vertical and horizontal helically-coiled tubes. The experiments are carried out in a range of pressure from 412 to 850 k Pa, inlet subcooling from 4.7 to 15.0℃, heat flux from 0.11 to 10.90 k W·m^-2 and mass flux from 147.5 to 443.7 kg·m^-2·s^-1. The subcooled flow boiling curves of the vertical and horizontal helically-coiled tubes are analyzed from single-phase forced convection to ONB. A parametric study is explored to investigate the effects of the experimental parameters on ONB. The results indicate that the wall superheat and temperature undershoot at ONB in vertical coil are smaller than that in horizontal coil. The heat flux and wall superheat of the ONB increase with the increase of the mass flux and inlet subcooling but decrease with the increase of the system pressure and helical diameter for both vertical and horizontal helically-coiled tubes. Furthermore, the dimensionless parameters are introduced to develop a new correlation for predicting the heat flux at ONB in helically-coiled tube. It is shown that 95.8% of the experimental data of the heat flux at ONB are within 20% of that calculated from the new correlation.
作者
孔令健
韩吉田
陈常念
刘志刚
KONG Lingjian;HAN Jitian;CHEN Changnian;LIU Zhigang(Energy Research Institute of Shandong Academy of Sciences, Jinan 250014, Shandong, China;School of Energy and Power Engineering, Shandong University, Jinan 250061, Shandong, China)
出处
《化工学报》
EI
CAS
CSCD
北大核心
2018年第5期1956-1963,共8页
CIESC Journal
基金
国家自然科学基金项目(51076084
51541604)
山东省自然科学基金项目(ZR2016YL005)~~
关键词
气液两相流
相变
传热
螺旋管
沸腾起始点
gas-liquid flow
phase change
heat transfer
helical coil
onset of nucleate boiling
