水平微细管内CO2流动沸腾压降特性

摘要

对CO2在内径1.5 mm水平微细管内流动沸腾换热摩擦压降特性进行了实验研究.实验工况:热通量(7.5～30 kW·m-2)、质量流率(300～600 kg·m-2·s-1)、饱和温度(-40～0℃).实验结果表明:热通量的增加对摩擦压降影响很小,几乎为零;质量流率是影响摩擦压降的最主要因素;随着饱和温度的升高摩擦压降减小;干度对摩擦压降影响主要由管内流型变化导致.将实测摩擦压降变化趋势绘制于CO2流态图中,比较发现理论预测摩擦压降最大值落在环状流末端区域.实验过程中对各个工况管内流态进行可视化研究,理论分析所采用的流态形式与实际CO2在微细通道内所具有的流态类型基本一致.%The study on flow boiling frictional pressure drop characteristics of CO2 in horizontal micro tube which internal diameter is 1.5mm was made. Experimental conditions: heat flux(7.5—30 kW·m-2), mass flow rate(300—600 kg·m-2·s-1), and saturation temperature(-40～0℃). Experimental results show: The increase of heat flux makes little effect on frictional pressure drop, almost zero; mass flow rate is the main factor that affects frictional pressure drop; the frictional pressure drop decreases as the saturation temperature increases; the effect of vapor quality on the frictional pressure drop is mainly caused by the change of the flow pattern in the tube. The trend of the experimental measured frictional pressure drop is plotted in CO2 flow regime chart and it is found that the theoretical prediction of the maximum value of the frictional pressure drop falls in the end of the annular flow region. Making visible study on flow regime change in each working condition during the experiment process and the theoretical pattern is consistent with the flow pattern of the actual CO2 in the micro tube in general.