Peer-reviewed veterinary case report
How liquid flows over tubes in spiral heat exchangers
By Dong L et al.·2026·Shandong Institute of Petroleum and Chemical Technology, China·View original on Europe PMC →
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Original publication title: Computational Fluid Dynamics Analysis of Falling Film Hydrodynamics in Spiral-Wound Heat Exchangers.
Plain-English summary
This study looked at how liquid flows over tubes in a type of heat exchanger called a spiral-wound heat exchanger. Researchers used advanced computer modeling to understand how different factors, like the speed of the liquid and the size and spacing of the tubes, affect how the liquid film behaves. They found that as the speed of the liquid increases, it changes from a stable flow to a more chaotic one, which creates more waves in the liquid. They also discovered that larger tubes can lead to uneven liquid distribution, while the right spacing between tubes helps the liquid flow better and cover the surface more evenly. Overall, this research provides important information that can help improve the design of these heat exchangers for better performance.
Abstract
This study presents a rigorous three-dimensional (3D) computational fluid dynamics (CFD) investigation into the complex hydrodynamic characteristics of an external falling liquid film flowing over horizontal tubes, focusing on a representative unit of the shell-side of a spiral-wound heat exchanger (SWHE). The primary objective is to quantitatively analyze the synergistic influence of key operating and structural parametersnamely, Reynolds number (Re), tube outer diameter (D), and tube spacing (S)on the liquid film profile, coverage uniformity, and flow regime transition. A volume of fluid (VOF) model was established and validated to accurately track the gas-liquid interface. The analysis reveals three major findings: (1) Increasing the Reynolds number from Re = 300 to Re = 2000 drives a critical flow regime transition from a stable columnar flow dominated by viscous and gravitational forces to a highly dynamic fan flow. This transition significantly intensifies interfacial wave activity, which is quantified by a positive correlation between wave amplitude and Re. (2) An increase in tube diameter (D) promotes the concentration of the liquid film into distinct columns, decreasing film coverage uniformity and increasing local film thickness, as surface tension and inertia compete for liquid distribution across the larger surface. (3) The tube spacing (S) critically governs the hydrodynamics in the intertube region; an optimal spacing (S = 6 mm in this study) is identified where liquid columns effectively merge and redistribute, maximizing coverage while minimizing flow restriction. This quantitative analysis provides crucial, mechanistically grounded hydrodynamic data essential for the optimized structural design of industrial SWHEs, aiming to enhance overall heat and mass transfer efficiency.
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Search related cases →Original publication on Europe PMC: https://europepmc.org/article/MED/41908365