Enhancing heat transfer at the micro-scale using elastic turbulence

Whalley, Richard D.; Abed, Waleed M.; Dennis, David; Poole, Robert J.

doi:10.1016/j.taml.2015.03.006

Cited by 44 publications

(27 citation statements)

References 23 publications

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“…Associated velocity boundary conditions are then given by (12) The resulting velocity profile is then of the form (13) Again considering Eqn. (10), this equation is now re-arranged by employing a nondimensional temperature, which is given by the following equation (14) Here, t m is the mixed-mean temperature and t 0 is the wall temperature.…”

Section: Energy Analysis For the Viscous Disk Pumpmentioning

confidence: 99%

“…Numerical investigations are described by Zhang et al [9,10] which address connections between elastic turbulence and enhancement of local flow mixing. Abed et al [11], and Whalley et al [12] describe enhancements in flow mixing from elastic turbulence which often result in enhancements of convective heat transfer rates, when compared for the same configuration and same experimental conditions. Of these investigations, Abed et al [11] experimentally consider convective heat transfer and fluid flow within a square cross-section serpentine channel with both polymeric viscoelastic fluids, and with constant-viscosity Newtonian Boger solutions as a basis of comparison.…”

Section: Introductionmentioning

confidence: 99%

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Elastic turbulence influences and convective heat transfer within a miniature viscous disk pump

Copeland

Ren

et al. 2017

International Journal of Heat and Mass Transfer

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Elastic turbulence is employed within the present investigation to enhance convective heat transfer at very small scales and at very low Reynolds numbers. A miniature viscous disk pump or VDP is utilized to investigate flow and heat transfer, where the latter are based upon energy balance measurements which utilize the mixed-mean temperature at the inlet and outlet of the viscous disk pump passage. The overall heat transfer rate is determined based upon a constant surface temperature thermal boundary condition, and upon a log-meantemperature difference approach. The VDP operates at rotation speeds of 500 RPM, 1000 RPM, 1500 RPM, 1800 RPM, and 2000 RPM, which produce overall shear rates across the flow cross section of 146.05 1/s, 292.1 1/s, 438.15 1/s, 525.78 1/s, and 584.2 1/s. A channel depth of 640 µm is employed. Elastic turbulence is induced by adding polyacrylamide to water solutions with 65 percent sucrose by mass. Significant enhancements of mixing and transport are observed, which are associated with the onset and development of elastic turbulence. Such behavior is verified, relative to an increased viscosity Boger fluid, using flow visualization results, rheometer viscosity variations with shear rate, and increases of overall magnitudes of convective heat transfer coefficient, which are augmented by as high as 240 percent. These comparisons are assessed relative to the Newtonian Boger fluid (which generally does not change viscosity as shear rate varies) at the same rotation speed, shear rate, flow passage height, and inlet temperature. As polymer concentration increases, elastic turbulence effects become more pronounced, and heat transfer coefficient magnitudes increase. This occurs such that Nusselt number ratios are strongly correlated with the meansquare magnitude of scalar temperature fluctuations at the outlet of the VDP. As a result, remarkable heat transfer coefficient enhancements due to elastic turbulence are demonstrated.

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Section: Energy Analysis For the Viscous Disk Pumpmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Elastic turbulence influences and convective heat transfer within a miniature viscous disk pump

Copeland

Ren

et al. 2017

International Journal of Heat and Mass Transfer

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show abstract

“…Two recent studies have reported heat transfer enhancements in the elastic turbulence regime. Traore et al (2015) documented a fourfold increase in the efficiency of heat transfer in a von Kármán swirling flow, while Whalley et al (2015) reported a threefold heat transfer enhancement in a 1-mm-diameter serpentine minichannel compared to a high-viscosity Newtonian sucrose solution at the cost of a significant pressure drop penalty. It would seem that a more practical approach would employ low-viscosity water as a coolant at the same applied pressure gradient required to pump the high-viscosity sucrose solution.…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Viscoelastic flow in an obstructed microchannel at high Weissenberg number

Nolan¹,

Agarwal²,

Lei³

et al. 2016

Microfluid Nanofluid

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“…As such, the present data show that polymer solutions can cause sharp growth in flow resistance as elastic turbulence develops. As a result, secondary flow develops in the viscoelastic flow due to the normal stresses, which are tied to streamline curvature within the C-shaped channel, leading to the onset and development of elastic turbulence [10]. According to Burghelea et al [21], the mixing and secondary flows associated with elastic turbulence are driven by the "coupling" between the primary circumferential shear flow and the secondary radial polymer elongation flow.…”

Section: E Variations Of Overall Pressure Rise and Shear Stressmentioning

confidence: 99%

“…Results indicate that viscoelastic fluids exhibit enhanced heat transfer coefficients, which are attributed to secondary motions associated with local and global normal stress variations. Abed et al [9] and Whalley et al [10] present experimental results for a serpentine channel to study convective heat transfer enhancements due to elastic turbulence. Results show that convective heat transfer magnitudes are enhanced by as much as 200-380%, for solutions with relatively low concentrations of polymers and relatively high concentrations of sucrose, compared to results for Newtonian, Boger solutions.…”

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confidence: 99%