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<p>This study investigates the hydrodynamic behavior of mini-channels produced by additive manufacturing (AM) for compact heat exchangers (CHEs). While AM enables the fabrication of complex geometries such as chaotic channels, it also introduces manufacturing imperfections, including high surface roughness and geometric deviations, which significantly affect pressure drop predictions. An experimental and numerical analysis was performed on a CHE prototype containing straight and chaotic circular channels with a nominal diameter of 2&#xa0;mm. Experiments were conducted using water and air as working fluids over a range of Reynolds numbers, with channel pressure drops varying from approximately 0.005 to 0.321&#xa0;bar. For the chaotic channel, printed vertically, the numerical model assuming a perfectly circular cross-section and incorporating measured surface roughness predicted the experimental pressure drop with an average deviation of approximately 20%, with numerical values ranging from about 0.005 to 0.123&#xa0;bar. In contrast, the straight channel, printed horizontally, presented deviations greater than 50% when modeled with an ideal circular geometry. This discrepancy was attributed to geometric distortions caused by the AM process. When the numerical model incorporated cross-section geometries based on the experimentally observed channel deformation, the deviation decreased to approximately 17.5%. Additional simulations considering non-uniform cross-sectional variations along the channel further improved the agreement with experimental data, reducing the average deviation to about 12%. The results demonstrate that random cross-sectional variations generated during the AM process have a stronger influence on pressure drop than surface roughness alone. These findings show that neglecting geometric variability leads to significant underprediction of pressure drop and highlight the importance of accurately representing real channel geometries in numerical models. They also indicate that nominally straight AM channels may exhibit pressure drop levels comparable to chaotic channels due to manufacturing-induced geometric irregularities, which affects the design and numerical modeling of compact heat exchangers.</p>

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Pressure drop in additively manufactured straight and chaotic minichannels: roughness and geometry effects

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年7月29日

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  • G. Zilio,
  • C. E. B. Corrêa,
  • G. S. M. Martins,
  • K. V. Paiva,
  • T. S. Possamai,
  • M. V. V. Mortean

摘要

This study investigates the hydrodynamic behavior of mini-channels produced by additive manufacturing (AM) for compact heat exchangers (CHEs). While AM enables the fabrication of complex geometries such as chaotic channels, it also introduces manufacturing imperfections, including high surface roughness and geometric deviations, which significantly affect pressure drop predictions. An experimental and numerical analysis was performed on a CHE prototype containing straight and chaotic circular channels with a nominal diameter of 2 mm. Experiments were conducted using water and air as working fluids over a range of Reynolds numbers, with channel pressure drops varying from approximately 0.005 to 0.321 bar. For the chaotic channel, printed vertically, the numerical model assuming a perfectly circular cross-section and incorporating measured surface roughness predicted the experimental pressure drop with an average deviation of approximately 20%, with numerical values ranging from about 0.005 to 0.123 bar. In contrast, the straight channel, printed horizontally, presented deviations greater than 50% when modeled with an ideal circular geometry. This discrepancy was attributed to geometric distortions caused by the AM process. When the numerical model incorporated cross-section geometries based on the experimentally observed channel deformation, the deviation decreased to approximately 17.5%. Additional simulations considering non-uniform cross-sectional variations along the channel further improved the agreement with experimental data, reducing the average deviation to about 12%. The results demonstrate that random cross-sectional variations generated during the AM process have a stronger influence on pressure drop than surface roughness alone. These findings show that neglecting geometric variability leads to significant underprediction of pressure drop and highlight the importance of accurately representing real channel geometries in numerical models. They also indicate that nominally straight AM channels may exhibit pressure drop levels comparable to chaotic channels due to manufacturing-induced geometric irregularities, which affects the design and numerical modeling of compact heat exchangers.