Journal of Green Energy Research and Innovation
Quarterly

Thermal Behavior of R134a Droplet in Dropwise Condensation Considering Marangoni Convection Flow on Horizontal and Vertical Surfaces for Refrigeration Systems

Document Type : Research article

Authors

Loghman Mohammadpour 1
Hesam Moghadasi 2

1 School of Mechanical Engineering, Iran University of Science and Technology (IUST), 16846-13114, Tehran, Iran.

2 Department of Mechanical Engineering, Faculty of Engineering, Arak University, Arak, 38156-88349, Iran.

10.61882/jgeri.3.2.78
Abstract
Dropwise condensation (DWC) increases phase change heat transfer efficiency, enabling more energy efficient thermal processes that directly support greener energy technologies and help lower overall carbon emissions. Correspondingly, this research work presents a numerical assessment of isolated R134a droplet during DWC on solid surfaces, focusing on the coupled impacts of Marangoni convection, contact angle across horizontal ( 𝛽 = 0°) and vertical (𝛽 = 90° ) surfaces to investigate their impact on heat transfer during DWC. In this regard, droplet geometry was modeled utilizing Surface Evolver, while computational fluid dynamics (CFD) simulations were performed in ANSYS FLUENT with a pressure-based solver and Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm. The simulation outcomes were validated through comparison with established theoretical models and previously published experimental measurements. Regarding the results, greater Marangoni numbers (π‘€π‘Ž ) enhance internal circulation, leading to more uniform temperature distributions and increased heat transfer coefficients. Also, contact angle was found to positively influence average heat flux (AHF) by reducing liquid–solid contact area, while vertical surfaces consistently exhibited higher AHF because of smaller droplet footprints. The results indicate that at and , the vertical surface yields an AHF that is nearly 4.5% superior than that of the horizontal surface. Furthermore, unlike previous studies, which primarily examined these phenomena in general condensation contexts, this work specifically addresses their implications for refrigeration systems. By investigating R134a droplets, the findings provide novel insights into droplet scale condensation mechanisms that can contribute to reducing energy consumption in refrigerators.‎‎‎

Highlights

❖ The impacts of Marangoni convection, contact angle and surface orientation in refrigerant R134a droplet on DWC utilizing CFD tools are evaluated.
❖ The influences of 𝑴𝒂 number on temperature distribution and average heat flux across horizontal and vertical surfaces are assessed.
❖ The vertical surface delivers about 4.5% greater average heat flux than the horizontal one at π‘΄π’‚ = 𝟏𝟏𝟎𝟐𝟎 and 𝜽 = 𝟏𝟏𝟎°.
❖ The findings offer refrigeration focused insights that can help reduce energy consumption. 

Keywords

CFD
DWC
Marangoni Convection
R134a Droplet
Horizontal and Vertical Surfaces

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The ethical issues, including plagiarism, informed consent, misconduct, data fabrication and/or falsification, double publication and/or submission, redundancy, have been completely observed by the authors.

Credit Authorship Contribution Statement

Loghman Mohammadpour: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Writing - original draft.  Hesam Moghadasi:  Conceptualization, Formal analysis, Investigation, Methodology, Supervision, Writing-review & editing.

 Bibliography

Loghman Mohammadpour received his M.Sc. degree in Mechanical Engineering from Iran University of Science and Technology, Tehran, Iran, in 2018. His research interests include energy condersion systems, computational fluid dynamics, fluid mechanics, dropwise condensation, porous media and heat transfer.

Hesam Moghadasi received his Ph.D. degree in Mechanical Engineering from Iran University of Science and Technology, Tehran, Iran, in 2022, and his Postdoc Fellow from Sharif university of technology, Tehran, Iran, in 2024. He was visiting researcher in department of Mechanical Engineering at Technical University of Denmark, Copenhagen, Denmark. He is currently an Assistant Professor at Department of Mechanical Engineering, Faculty of Engineering, Arak University, Arak, Iran. His research expertise lies in energy conversion systems, heat transfer amelioration, multiphase flow, computational fluid dynamics, nanofluids, renewable energy, surface science, boiling and condensation.

Citation
L. Mohammadpour and H. Moghadasi, "Thermal Behavior of R134a Droplet in Dropwise Condensation Considering Marangoni Convection Flow on Horizontal and Vertical Surfaces for Refrigeration Systems," Journal of Green Energy Research and Innovation, vol. 3, no. 2, pp. 78-89, 2026.

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Journal of Green Energy Research and Innovation
Volume 3, Issue 2
Spring 2026
Pages 78-89

  • Receive Date 28 November 2025
  • Revise Date 27 January 2026
  • Accept Date 04 February 2026
  • Publish Date 01 June 2026

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