Measure of bubble non-uniformity within circular region in a direct-contact heat exchanger

• Published in: International journal of heat and mass transfer 2017-07, Vol.110, p.257-261
• Main Authors: Xiao, Qingtai, Pan, Jianxin, Lv, Zhihan, Xu, Jianxin, Wang, Hua
• Format: Article
• Language: English
• Subjects: Bubble swarm; Bubbles; Circular region; Circularity; Direct-contact heat transfer; Discrepancy method; Distribution uniformity; Experiments; Heat exchangers; Simulation
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2017.03.042

•This paper discussed the difference of mixing uniformity in the direct-contact boiling heat transfer process.•A quantitative metric of mixing uniformity is used to characterize the bubble patterns within circular region.•The space-time features of the mixing transient are derived when the bubble swarms distribute in circular region. The study of bubble swarm distributions in a direct-contact heat exchanger was addressed both theoretically and experimentally. But recently developed approach based on uniform design for measuring bubbles uniformity and mixing efficiency within rectangular or square region cannot be used to characterize the mixture homogeneity and mixing time within circular region. This paper discussed the difference between rectangular or square region and circular region. A quantitative metric of mixing uniformity is used to characterize the bubble patterns within circular region. Simulation studies are also used to illustrate the proposed methodologies while the experimental case considered demonstrate that the proposed approach evaluated the experimental data rather well. The space-time features of the mixing transient have been successfully derived when the bubble swarms or other objects distribute in a circular region. This work brings new insights to evaluate mixing quality of different systems practically, which has a high degree of accuracy (the percentage of enhancing achieved is about 40%).