The contact angle of nanofluids as thermophysical property

Research output: Contribution to journalArticle

Abstract

Droplet volume and temperature affect contact angle significantly. Phase change heat transfer processes of nanofluids – suspensions containing nanometre-sized particles – can only be modelled properly by understanding these effects. The approach proposed here considers the limiting contact angle of a droplet asymptotically approaching zero-volume as a thermophysical property to characterise nanofluids positioned on a certain substrate under a certain atmosphere. Graphene oxide, alumina, and gold nanoparticles are suspended in deionised water. Within the framework of a round robin test carried out by nine independent European institutes the contact angle of these suspensions on a stainless steel solid substrate is measured with high accuracy. No dependence of nanofluids contact angle of sessile droplets on the measurement device is found. However, the measurements reveal clear differences of the contact angle of nanofluids compared to the pure base fluid. Physically founded correlations of the contact angle in dependency of droplet temperature and volume are obtained from the data. Extrapolating these functions to zero droplet volume delivers the searched limiting contact angle depending only on the temperature. It is for the first time, that this specific parameter, is understood as a characteristic material property of nanofluid droplets placed on a certain substrate under a certain atmosphere. Together with the surface tension it provides the foundation of proper modelling phase change heat transfer processes of nanofluids.

Details

Authors
  • M. Hernaiz
  • V. Alonso
  • P. Estellé
  • L. Doretti
  • S. Mancin
  • N. Çobanoğlu
  • Z. H. Karadeniz
  • N. Garmendia
  • M. Lasheras-Zubiate
  • L. Hernández López
  • R. Mondragón
  • R. Martínez-Cuenca
  • S. Barison
  • A. Kujawska
  • A. Turgut
  • A. Amigo
  • G. Huminic
  • A. Huminic
  • M. R. Kalus
  • K. G. Schroth
  • M. H. Buschmann
Organisations
External organisations
  • University of Padova
  • Jaume I University
  • Wrocław University of Science and Technology
  • Dokuz Eylül University
  • Transylvania University Brasov
  • Institut für Luft- und Kältetechnik Dresden
  • IK4-Tekniker
  • University of Rennes I
  • Izmir Katip Celebi University
  • Naitec
  • Istituto di Chimica della Materia Condensata e di Tecnologie per l'Energia (ICMATE)
  • University of Santiago de Compostela
  • Particular GmbH
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Energy Engineering

Keywords

  • Contact angle, Experimental strategy, Influence of temperature, Influence of volume, Nanofluids, Round robin test
Original languageEnglish
Pages (from-to)393-406
Number of pages14
JournalJournal of Colloid and Interface Science
Volume547
Publication statusPublished - 2019
Publication categoryResearch
Peer-reviewedYes