直接接触式沸腾换热过程气泡混合均匀度评价

针对直接接触式沸腾换热过程中气泡群扰动的多相流体混合性能评价问题，提出一种基于图像处理技术与像素偏差理论量化混合复杂流体流型均匀性的精确检测与度量新方法。通过气泡群RGB图像的灰度矩阵进行偏差计算，精确地定量描绘了直接接触式换热过程中的气-液混合状态，其值大小反映了气泡群的分布状况，而不同工况下混合均匀时间的差异反映了不同多相体系的均匀性差异；对偏差序列进行正态性检验，发现其近似符合正态分布；运用混沌检测方法对序列进行混沌特征分析，发现整个混合过程是混沌的。通过一个简单的指标实现了复杂条件下气泡群的量化和表征，为多相流流型识别提供了新的分析思路并指导换热过程的混沌强化。

Assessing mixing uniformity of bubbles in direct-contact boiling heat transfer process

In order to assess the mixing performance of multiphase flow disturbed by bubble swarms in direct-contact boiling heat transfer process, a novel technique based on image processing technique and pixel discrepancy theory was proposed to test and measure the mixing uniformity of complex fluids. The gray scale matrix of bubbles RGB image was used to calculate discrepancy. The mixed state of gas-liquid in direct-contact heat transfer was characterized accurately and quantitatively. The values reflect the distribution status of bubbles swarm. Different mixing uniformity of multiphase flow systems have different mixing time. Pixel discrepancy time series were employed for normality test and chaotic detection. It is found that the data is approximate normal distribution and the whole mixing processes are chaotic. A simple method was used to solve a complicated problem that the quantification and characterization of bubbles behavior under the complicated condition. The alternative route brings new insights to study multiphase flow identification and can act as a guide to enhancing the chaotic behavior of systems.