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.
Wenzhen XIONG Jianxin XU Junwei HUANG
. Feature extraction and distribution of continuous phase in direct contact boiling heat transfer process[J]. The Chinese Journal of Process Engineering, 2019
, 19(4)
: 704
-713
.
DOI: 10.12034/j.issn.1009-606X.218229
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