Boiling flow patterns and dry-out characteristics of R-1234ze(E) in a plate heat exchanger | |
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Year of publication | 2020 |
Title of paper | Boiling flow patterns and dry-out characteristics of R-1234ze(E) in a plate heat exchanger |
Author | DongChan Lee, ChangUk Jo, Byeongsu Kim, Yongchan Kim |
Publication in journal | International Journal of Heat and Mass Transfer |
Publication date | 8 August 2020 |
Volume & other data | Volume 161, 120308 |
Abstract | In this study, boiling flow patterns and dry-out characteristics of R-1234ze(E) in a plate heat exchanger (PHE) are investigated through visualizations and surface temperature measurements. The boiling flow patterns in the PHE are classified into three regimes by reflecting an evident flow direction and intermittent flooding (IF): rough liquid film flow, pulsating annular flow, and steady annular flow. Boiling mechanisms in the liquid-preferred and vapor-preferred paths are analyzed in a single channel. A boiling flow pattern map of R-1234ze(E) in the PHE is developed in terms of liquid and vapor superficial momentums, and the criteria for the transitions of the flow regimes are proposed to provide a reference for predicting flow characteristics during phase changes. Based on the measured surface temperatures, the partial dry-out is observed at medium to high vapor qualities in the center of the vapor-preferred path owing to the lack of the liquid phase. In addition, the relationships between the IF, partial dry-out, and heat transfer coefficients are comprehensively analyzed with physical interpretations. |
Keywords | Flow pattern, Dry-out, Plate heat exchanger, Flow visualization, Low gwp |
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HVAC
고려대학교 냉동공조 및 이상유동 연구실