Time-dependent structural breakdown of microencapsulated phase change materials suspensions |
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| Authors: | Vinh Duy Cao Carlos Salas-Bringas Reidar Barfod Schüller Anna M. Szczotok |
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| Affiliation: | 1. Faculty of Engineering, ?stfold University College, Halden, Norway;2. Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, ?s, Norway;3. Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, ?s, Norway;4. Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, ?s, Norway;5. Department of Chemical Engineering, University of Castilla – La Mancha, Ciudad Real, Spain |
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| Abstract: | Microencapsulated phase change materials (MPCM) suspensions are multi-phase heat transfer fluids which exploit the latent heat of phase change materials. The effect of MPCM on the rheological properties of suspensions of microcapsules in glycerol were investigated to explore the suitability of the suspensions as a pumpable heat transfer fluid. Three different rheological models were utilized to characterize the time-dependent structural breakdown of the suspensions, and the second-order structural kinetic model was found to give a better fit to the experimental data than the Weltman and Figoni-Shoemaker models. The MPCM form agglomerates, which are disrupted by shear forces. The breakdown of the agglomerated structures was most pronounced at high shear rates where the microcapsules are subjected to stronger disruptive forces. More agglomerates are present at higher concentrations, which causes a stronger breakdown of the agglomerated structures when the concentration is raised. The time-dependent structural breakdown of MPCM suspensions plays an important role for improving the efficiency of heat transfer liquids based on such materials.GRAPHICAL ABSTRACT | |
| Keywords: | Microencapsulated phase change materials rheology the second-order structural kinetic model time-dependent behaviour |
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