Nanotech 2006 Vol. 2
Nanotech 2006 Vol. 2
Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, Volume 2

Micro & Nano Fluidics Chapter 8

Computational Heat Transfer and Two-phase Flow in Miniature Tubes

Authors: D. Lakehal and C. Narayanan

Affilation: ASCOMP, Switzerland

Pages: 621 - 624

Keywords: CFD, level sets, heat transfer, micro tubes

Abstract:
We will report on our recent advances made in predicting this class of flow, using the Level Set approach, in which we have incorporated phase-change capabilities, surface tension and triple-line dynamics models based on the Young’s unbalanced forces. We will focus on the tremendous role played by flow regime in controlling heat transfer. We will show that a tiny change in the gas-phase Reynolds number can change a bubbly flow regime into a bubbly-slug flow regime, which in turn leads to an appreciable increase in local heat transfer. The 2D axisymmetric simulations were performed in a 1mm diameter tube heated at the surface, in which air bubbles were then injected into a water stream. The computational strategy combines the unsteady Navier-Stokes equations for the flow and Level Sets for interface dynamics. These novel methods were found to accurately predict various multi-fluid micro-flow phenomena. Figure 1 shows predicted bubbly/slug flow regime. The heat removal rate is shown to increase as compared to the single-phase flow regime (upper panel), and was found to be higher than the bubbly flow regime (see isocontours of temperature –blue: low; red: high). The presence of phase change will add to the heat transfer removal rate.

Computational Heat Transfer and Two-phase Flow in Miniature Tubes

ISBN: 0-9767985-7-3
Pages: 893
Hardcopy: $119.95