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Entropy 2016, 18(4), 113;

Second Law Analysis of Adiabatic and Non-Adiabatic Pipeline Flows of Unstable and Surfactant-Stabilized Emulsions

Department of Chemical Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
Academic Editor: Milivoje M. Kostic
Received: 17 December 2015 / Revised: 5 March 2016 / Accepted: 25 March 2016 / Published: 30 March 2016
(This article belongs to the Special Issue Exploring the Second Law of Thermodynamics)


Entropy generation, and hence exergy destruction, in adiabatic flow of unstable and surfactant-stabilized emulsions was investigated experimentally in different diameter pipes. Four types of emulsion systems are investigated covering a broad range of the dispersed-phase concentration: (a) unstable oil-in-water (O/W) emulsions without surfactant; (b) surfactant-stabilized O/W emulsions; (c) unstable water-in-oil (W/O) emulsions without surfactant; and (d) surfactant-stabilized W/O emulsions. The entropy generation rate per unit pipe length is affected by the type of the emulsion as well as its stability. Unstable emulsions without any surfactant present at the interface generate less entropy in the turbulent regime as compared with the surfactant-stabilized emulsions of the same viscosity and density. The effect of surfactant is particularly severe in the case of W/O emulsions. In the turbulent regime, the rate of entropy generation in unstable W/O emulsions is much lower in comparison with that observed in the stable W/O emulsions. A significant delay in the transition from laminar to turbulent regime is also observed in the case of unstable W/O emulsion. Finally, the analysis and simulation results are presented on non-adiabatic pipeline flow of emulsions. View Full-Text
Keywords: entropy; exergy; emulsion; two phase; flow; pipeline entropy; exergy; emulsion; two phase; flow; pipeline

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Pal, R. Second Law Analysis of Adiabatic and Non-Adiabatic Pipeline Flows of Unstable and Surfactant-Stabilized Emulsions. Entropy 2016, 18, 113.

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