Experimental investigation of surface roughness/wettability pattern effect on crystallization fouling over falling-film flow

Journal Article · 12 January 2024 · Desalination

DOI: https://doi.org/10.1016/j.desal.2024.117324 · OSTI ID:2339619

Zaman, Mohammad Arafat ^[1]; Wang, Sophie ^[2]

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1. University of Illinois at Urbana-Champaign, IL (United States); Univesityof Illinois
2. University of Illinois at Urbana-Champaign, IL (United States)

In many industries, including desalination, scaling in heat exchangers is a persistent issue, and most methods of scaling control involve environmentally hazardous chemical additives. Exploiting the effects of surface features and flow-imposed shear on salt deposition might introduce a new approach to scale management, opening the possibility of self-cleaning surfaces. In this work, we experimentally explore surface roughness and wettability patterns interaction with salt deposition and flow shear. Heat transfer and scale mass deposition on flat surfaces are measured during thin-film evaporation of calcium sulfate solution. A wide range of surface roughness (0.027–2.66 μm) is studied at fixed flow and heat flux conditions. Due to improved mixing, heat transfer is enhanced with rougher surfaces initially; however, degrades more quickly than smoother surfaces. Following a period of initial mass deposition fluctuation, a steady scaling stage is observed, with rough surfaces scaling more than smooth surfaces. Wettability patterned surfaces can suppress crystal nucleation without sacrificing overall surface wetting, resulting in antifouling performance and heat transfer enhancement. Scale mass deposition on a patterned surface is reduced by 60 %, and 27 % heat transfer improvement over the baseline surface is found. Furthermore, this study provides guidance to surface manipulation for heat transfer improvement and fouling mitigation.

• Research Organization: University of Illinois at Urbana-Champaign, IL (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
• Grant/Contract Number: EE0008392
• OSTI ID: 2339619
• Journal Information: Desalination, Journal Name: Desalination Vol. 575; ISSN 0011-9164
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English