螺旋管内汽液两相流密度波型脉动流动传热试验研究

AN EXPERIMENTAL INVESTIGATION OF OSCILLATORY HEAT TRANSFER IN HELICAL COILED TUBE WITH STEAM WATER TWOPHASE DENSITY WAVE OSCILLATION FLOW

详细介绍了在沸腾通道内部发生汽液两相流水动力不稳定性而出现周期性密度波型脉动时，脉动流动过程中瞬态和时均传热系数的实验研究结果。实验在以水为工质、以螺旋管作沸腾蒸发试验段的中低压闭式循环系统上进行，试验参数范围为：压力p=05～35 MPa，质量流速G=200～2 100 kg/(m2·s)，工质进口过冷度ΔTsub=20～90 ℃，试验段壁面热负荷qw=0～540 kW/m2，密度波脉动的周期为T=125～14 s，且主要集中在4～10 s范围内。对密度波脉动过程中瞬态及时均传热系数和其它主要参数的基本特征与变化规律作了分析和描述，提出了表征密度波脉动传热的新的特征准则数和传热系数计算式。

Some results of experimental research on the oscillatory heat transfer charact eristics including transient and timeaverage heat transfer coefficients for vapourwater two phase flow during the processes of densitywave oscillation occ urring in helical coiled tube boiling channel system were presented. The experim ent was performed at a closedcirculation test loop under the following parameters ranges:system pressure p＝05～3.5 MPa; Mass flow rate G＝200～2100 kg/(m２·s); Intel subcooling of working fluid ΔTsub=20～90 ℃; Hea t flux of wall of test section qw=0～540 kW/m2. The range of oscillatory periods of densitywave oscillations T was 1.25～14 s and mainly concentra ted in the range of 4～10 s. The features of transient and timeaveraged heat t ransfer coefficients were described and analyzed. New mechanisms and nondimens ional parameters to characterize the features of heat transfer process were prop osed, and a correlation for the prediction of oscillatory heat transfer coeffici ents was obtained on the basis of experimental data and mechanism analysis.