Three-dimensional distribution of liquid film thickness and heat transfer coefficient in horizontal flat tube falling film evaporation

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences Pub Date : 2025-07-03 DOI:10.1016/j.ijthermalsci.2025.110087

Wenjie Deng , Zhenhua Quan , Chunduo Song , Chenyang Du , Lincheng Wang , Yaohua Zhao

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引用次数: 0

Abstract

Horizontal tube falling film evaporators (HTFFEs) are widely used in the sustainable energy sector due to their superior heat transfer performance. To further enhance heat and mass transfer efficiency and improve energy utilization, a novel horizontal flat tube falling film evaporator (HFTFFE) is proposed. Numerical modeling of the HFTFFE process was conducted using the Volume of Fluid (VOF) model to analyzed the three-dimensional flow characteristics, liquid film thickness (δ), and heat transfer coefficient (h), with comparisons to the HTFFE. The results show that the circumferential falling film flow processes through five stages: free falling, liquid film impact, free flow, vertical wall falling film, and complete flow. Axially, the liquid film exhibits a pattern of peaks and valleys, with δ and h displaying consistent trends. Circumferentially, δ decreases rapidly at first, then stabilizes, while its axial variation remains minimal. The liquid film impact zone records the highest δ and h, whereas the complete flow zone shows the lowest values. Increasing the Spray Reynolds number (Re) significantly raises δ at the crest. The Re, heat flux density, and spray height all positively influence h. Compared to a traditional HTFFE of equivalent cross-sectional perimeter, the HFTFFE shortens flow time by 10.3 %, reduces average liquid film thickness by 11.4 %, and increases the average heat transfer coefficient by 5.1 %. These findings highlight the superior flow and heat transfer performance of the HFTFFE, making it a promising option for sustainable energy applications.

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水平平管降膜蒸发液膜厚度及传热系数的三维分布

卧式降膜蒸发器由于其优越的传热性能在可持续能源领域得到了广泛的应用。为了进一步提高传热传质效率，提高能量利用率，提出了一种新型的水平平管降膜蒸发器（HFTFFE）。采用流体体积（Volume of Fluid， VOF）模型对hffffe过程进行数值模拟，分析其三维流动特性、液膜厚度（δ）和换热系数(h)，并与HTFFE进行比较。结果表明：环向降膜流动经历了自由落体、液膜冲击、自由流动、垂壁降膜和完全流动五个阶段；在轴向上，液膜呈现出波峰和波谷模式，δ和h的变化趋势一致。在周向上，δ先迅速下降，然后趋于稳定，而其轴向变化保持最小。液膜冲击区δ和h值最高，全流区δ和h值最低。增加喷雾雷诺数（Re）可显著提高峰处δ。Re、热流密度和喷淋高度均对h有正向影响。与具有等效截面周长的传统HTFFE相比，HTFFE的流动时间缩短了10.3%，平均液膜厚度减少了11.4%，平均换热系数提高了5.1%。这些发现突出了htfffe优越的流动和传热性能，使其成为可持续能源应用的一个有前途的选择。

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来源期刊

International Journal of Thermal Sciences 工程技术-工程：机械

CiteScore

8.10

自引率

11.10%

发文量

531

审稿时长

55 days

期刊介绍： The International Journal of Thermal Sciences is a journal devoted to the publication of fundamental studies on the physics of transfer processes in general, with an emphasis on thermal aspects and also applied research on various processes, energy systems and the environment. Articles are published in English and French, and are subject to peer review. The fundamental subjects considered within the scope of the journal are: * Heat and relevant mass transfer at all scales (nano, micro and macro) and in all types of material (heterogeneous, composites, biological,...) and fluid flow * Forced, natural or mixed convection in reactive or non-reactive media * Single or multi–phase fluid flow with or without phase change * Near–and far–field radiative heat transfer * Combined modes of heat transfer in complex systems (for example, plasmas, biological, geological,...) * Multiscale modelling The applied research topics include: * Heat exchangers, heat pipes, cooling processes * Transport phenomena taking place in industrial processes (chemical, food and agricultural, metallurgical, space and aeronautical, automobile industries) * Nano–and micro–technology for energy, space, biosystems and devices * Heat transport analysis in advanced systems * Impact of energy–related processes on environment, and emerging energy systems The study of thermophysical properties of materials and fluids, thermal measurement techniques, inverse methods, and the developments of experimental methods are within the scope of the International Journal of Thermal Sciences which also covers the modelling, and numerical methods applied to thermal transfer.