直接接触沸腾换热过程连续相特征提取及分布规律

利用支持向量机(SVM)理论构建了有机工质?导热油直接接触沸腾换热过程连续相特征提取方法，获得了导热油和气泡群两相流流型的拓扑结构。对9组正交实验工况获得的两相流图像分别进行连续相特征提取和同调群计算，得到量化连续相数量的1维和0维贝蒂数?1和?0用于粗略估计气泡群数量，并与传统数字图像处理方法的结果比较，对比了换热效率较好和较差情况下形态学开运算对SVM方法的影响，建立了两相流贝蒂数演化规律与换热效率的关联性，比较了传统方法获得的气泡群数量和SVM方法获得的连续相“洞”的数量的演化规律。结果表明，SVM结合贝蒂数方法不仅可准确量化导热油连续相，且可粗略地表征气泡分散相；L6工况(连续相导热油液位高度Z=0.5 m、初始换热温差?T=120℃、分散相工质流率U0=0.04 m/s、连续相导热油流率Uc=0.15 kg/s)下连续相数量变化几乎重叠，相对波动较小，而L4工况(Z=0.5 m, ?T=80℃, U0=0.06 m/s, Uc=0.3 kg/s)下连续相数量偏离程度较大；SVM方法获得的连续相和气泡群个数演化曲线同步，且混合时间相同，?1和?0中位数偏离程度的局部最小值可作为性能指标之一，通过实验验证可优选出换热效果最好的工况。

Feature extraction and distribution of continuous phase in direct contact boiling heat transfer process

Based on support vector machine (SVM) theory, a continuous phase feature extraction method for organic working fluid and heat conducting oil direct contact boiling heat transfer was constructed, and the two-phase flow pattern topological structure was obtained. Continuous phase feature extraction and homology group calculation were carried out for two-phase flow images of 9 sets orthogonal experimental conditions, the continuous phase quantizing the quantity index ?1 and the bubbles estimation number index ?0 were obtained, then the traditional digital image processing methods were compared and analyzed. The influence of morphological opening operation on SVM method was compared between in better and worse of the heat transfer efficiency. The number of bubble groups obtained from the traditional method and the quantitative evolution rule of the continuous phase hole obtained by the SVM method were compared. The results showed that SVM combined with Betty number method can not only accurately quantify the continuous phase of heat conduction oil, but also roughly represent the dispersed phase of bubbles. It was found that the number of continuous phase changes almost overlapped and relatively small fluctuation in L6 condition (thermal conductive oil height Z=0.5 m, initial temperature difference ?T=120℃, working medium flow rate U0=0.04 m/s, thermal conductive oil flow rate Uc=0.15 kg/s), but the number of continuous phases deviated from a larger degree in L4 condition (Z=0.5 m, ?T=80℃, U0=0.06 m/s, Uc=0.3 kg/s). The relationship between the evolution rule of Betty number and heat transfer efficiency was established. The evolution curves of continuous phase and bubble group number showed synchronization, and the time of mixing was the same. The local minimum of the median distance between the two numbers can be used as one of the performance indicators, the best heat transfer condition was selected through experiment. This method can be used to study a series of problems concerning the quantitative evolution of two phase flow topological structure.