Field synergy analysis of different flow patterns in falling-film dehumidification system with horizontal pipes
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Field synergy analysis of different flow patterns in falling-film dehumidification system with horizontal pipes NIU Run-ping(牛润萍), KUANG Da-qing(匡大庆), WANG Shi-zheng(王世政), CHEN Xiao-yi(陈潇义) Beijing Engineering Research Center of Sustainable Energy and Buildings, Beijing University of Civil Engineering and Architecture, Beijing 100044, China © Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract: Effects of the flow pattern of intertubular liquid film on mass and heat transfer synergies in a falling-film dehumidification system with horizontal pipes are studied. A flow model of the dehumidifying solution between horizontal pipes is established using Fluent software, the rule of transitions of the flow pattern between pipes is studied, critical Reynolds numbers of flow pattern transitions are obtained, and the accuracy of the model is verified by experiments. The mass transfer synergy angle and heat transfer synergy angle are respectively used as evaluation criteria for the mass transfer synergy and heat transfer synergy, and distribution laws of the synergy angles for droplet, droplet columnar and curtain flow patterns are obtained. Simulation results show that the mass transfer synergy angles corresponding to droplet, droplet columnar and curtain flow patterns all rise to a plateau with time. The mean mass-transfer synergy angle is 98° for the droplet flow pattern, higher than 96.5° for the droplet columnar flow pattern and 95° for the curtain flow pattern. The results show that the mass transfer synergy of the droplet flow pattern is better than that of the droplet columnar flow pattern and that of the curtain flow pattern. Key words: film falling between horizontal pipes; fluent software; flow pattern of liquid film; synergy angle; mass and heat transfer Cite this article as: NIU Run-ping, KUANG Da-qing, WANG Shi-zheng, CHEN Xiao-yi. Field synergy analysis of different flow patterns in falling-film dehumidification system with horizontal pipes [J]. Journal of Central South University, 2020, 27(8): 2353−2366. DOI: https://doi.org/10.1007/s11771-020-4454-3.
1 Introduction Liquid desiccant dehumidification is a new technology developed in the field of air conditioning in recent years. Compared with traditional compression refrigeration dehumidification technology, it has obvious characteristics of energy saving and high efficiency. Many scholars have studied liquid desiccant dehumidification systems, especially systems that adopt falling-film dehumidification between
horizontal pipes. ZENG et al [1] studied the liquid desiccant dehumidification system based on condensation heat regeneration. The results show that the flow rate and temperature of air and solution have positive effect on the regeneration rate. Under typical working conditions in summer, when the solution concentration is 21.20%−24.91%, the condensing heat utilization rate fluctuates from 0.416 to 0.507, and reducing the solution concentration is conducive to improving the condensing heat utilization ra
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