Microconvective Thermal Conductivity in Disperse Two-Phase Mixtures as Observed in a Low Velocity Couette Flow Experiment

[+] Author and Article Information
C. W. Sohn, M. M. Chen

Department of Mechanical and Industrial Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801

J. Heat Transfer 103(1), 47-51 (Feb 01, 1981) (5 pages) doi:10.1115/1.3244428 History: Received July 02, 1980; Online October 20, 2009


Eddy transport associated with microscopic flow fields in shearing two-phase flows was investigated. Although such microconvective effects are expected to be present in all disperse two-phase flows, usually they are masked by other collateral mechanisms and could not be studied critically. In the present study, effective thermal conductivities of neutrally buoyant solid-fluid mixtures were measured in a rotating Couette flow apparatus. Low Reynolds numbers were used to avoid the effects of turbulence. Significant enhancement in effective thermal conductivity was observed when the Ped were high. Here Ped = ed2 /αf where e is the local mean shear rate, d is the particle diameter, and αf is the thermal diffusivity of the fluid. Volume fractions employed were φ = 0.15 and 0.30 for polyethylene beads (2.9 mm in diameter) in a mixture of silicone oil and kerosene, and φ = 0.15 for polystyrene particles (0.3 mm in diameter) in a mixture of silicone oil and Freon-113. Single-phase liquid mixtures were also measured in various shear rates to show that the thermal conductivity was independent of shear rate and hence the observed phenomenon was not an instrumental artifact. The dependence of conductivity on particle Peclet number appeared to approach a power law relationship ke ∝ Ped 1/2 for high Peclet numbers (300 < Ped < 2000).

Copyright © 1981 by ASME
Your Session has timed out. Please sign back in to continue.





Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In