过冷度对R134a流动沸腾迟滞特性的影响

Influence of Subcooling Degree on Flow Boiling Hysteresis Characteristics of R134a

实验研究了过冷度对卧式螺旋管内R134a流动沸腾迟滞特性的影响,通过逐渐改变热流密度,记录壁温变化情况,绘制出增大和减小热流密度时的沸腾曲线,通过曲线分析得到沸腾迟滞特性。成核滞后方面,过冷度越大,成核滞后现象越明显,从过冷度影响核化孔隙内蒸汽冷凝的角度分析了机理。湮灭滞后方面,过冷度越大,湮灭滞后现象越明显,从过冷度影响增、减热流密度时汽化核心数量的角度分析了机理。

The influence of subcooling degree on the flow boiling hysteresis characteristics of R134a in horizontal helically-coiled tube is experimentally studied.By gradually changing the heat flux and recording the wall temperature changes,the boiling curves of increasing and decreasing heat flux are plotted,and the boiling hysteresis characteristics are obtained through curve analysis.In terms of temperature overshoot hysteresis,the larger the subcooling degree is,the more obvious the phenomenon of temperature overshoot hysteresis will be.The mechanism is analyzed from the perspective of the influence of subcooling degree on vapor condensation in nucleated pores.In terms of temperature deviation hysteresis,the larger the subcooling degree is,the more obvious the phenomenon of temperature deviation hysteresis will be.The mechanism is analyzed from the angle of influence of subcooling degree on the number of vaporizing cores when the heat flux is increased or decreased.