Numerical calculations are performed to investigate the effect of viscous dissipation on the temperature rise and friction numbers for laminar water flows in micro-tubes. The calculated values are compared with those determined from reported experimental data for glass and diffused silica micro-tubes (D = 16 – 101 μm and L/D = 625 – 1479). The results confirm a definite slip at the wall with slip lengths of ∼ 0.7 μm and 1.0 μm, which decrease the friction number and the temperature rise in the micro-tubes, but their effect gradually diminishes as either D or L/D increases. The friction number decreases exponentially as D decreases and, to a lesser extent, as L/D increases. The effect of L/D on the friction number is insignificant for micro-tube diameters ≤ 20 μm. For D > 400 μm, the friction number approaches that of Hagen-Posieuille of 64 for macro-tubes when L/D > 1500, but approaches higher values at smaller L/D. The dimensionless analytical expression developed for calculating the friction number and the temperature rise for water flows in micro-tubes is in good agreement with both the numerical and experimental results.
- Heat Transfer Division
Viscous Dissipation in Laminar Water Flows in Micro-Tubes
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Yang, I, & El-Genk, MS. "Viscous Dissipation in Laminar Water Flows in Micro-Tubes." Proceedings of the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 2. Vancouver, British Columbia, Canada. July 8–12, 2007. pp. 313-322. ASME. https://doi.org/10.1115/HT2007-32497
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