Heat Transfer Enhancement in Wavy Micro-channels via Multi-harmonic Surfaces

Faculty #66
Discipline: Technology & Engineering
Subcategory: STEM Research

Arturo Pacheco-Vega - California State University, Los Angeles
Co-Author(s): Justin Moon, California State University, Los Angeles, Los Angeles, CA 90032; J. Rafael Pacheco, SAP America Inc., Tempe, AZ 85281.

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In this study, three-dimensional numerical simulations were performed to investigate the enhancement of heat transfer in multi-harmonic micro-scale wavy channels. The focus was on the influence of channel surface-topography on the enhancing mechanisms. A single-wave device of 0.5 mm by 0.5 mm by 20 mm length is used as baseline, and new designs are built with harmonic-type surfaces. The channel is enclosed by a solid block, with the bottom surface within the sinusoidal region being exposed to a 47 W/cm2 heat flux. The numerical solutions of the governing equations for an incompressible laminar flow and conjugate heat transfer were obtained via finite elements. By using the ratio of the Nusselt number for wavy to straight channels, a parametric analysis ? for a set of cold-water flowrates (Re = 50, 100, and 150) ? showed that the addition of harmonic surfaces enhances the transfer of energy, and that such ratio achieves the highest value with wave harmonic numbers of n = +/- 2. Use of a performance factor (PF), defined as the ratio of the Nusselt number to the pressure drop, shows that, surprisingly, the proposed wavy multi-harmonic channels are not as efficient as the single-wave geometries. This outcome is thought to be, primarily, due to the uncertainty associated with the definition of the Nusselt number used in this study, and establishes a direction to investigate the development of a more accurate definition.

Funder Acknowledgement(s): This work has been supported by an NSF HRD-1547723 grant.

Faculty Advisor: None Listed,
NSF Affiliation: CREST