Numerical Analysis of Roughness Effect on Mini and Microchannels: Hydrodynamics and Heat Transfer

A three-dimensional numerical simulation of flow through mini and microchannels with designed roughness is conducted here. The effect of the roughness height (surface roughness), geometry, Reynolds number on the friction factor, and Nusselt number is investigated. The study is carried out by employing CFD software, CFX. Our work focuses on a water flow inside a circular mini-channel of 1 mm and microchannels of 500 and 100 m in diameter. The speed entry varies from 0.1 m/s to 20 m/s. The general trend can be observed that bigger sizes of roughness element lead to higher flow resistance. It is found that the friction factor increases in a nonlinear fashion with the increase in obstruction height. Particularly, the effect of roughness can no longer be ignored at relative roughness height higher than 3%. A significant increase in Poiseuille number is detected for all configurations considered. The same observation can be done for Nusselt number. The transition zone between laminar and turbulent flow depends on the channel diameter.

Authors:

• El-Ghalia Filali
• Cherif Gadouche
• Mohamed Tahar

Keywords:

• Heat transfer
• hydrodynamics
• micro-channel
• roughness.

References:

[1] P. Gao, S. Le Person, M. Favre-Marinet, “Scale effects on
hydrodynamics and heat transfer in two-dimensional mini and
microchannels” International Journal ofThermal Sciences, 2002, vol.
41, pp. 1017–1027.
[2] Shah, R.K. and London, A.L. “Laminar Flow Forced Convection in
Duct”, Academic Press 1978.
[3] S. G. Kandlikar, S.; Joshi and S. Thaine, “Effect of surface roughness on
heat transfert and fluid flow characteristics at low reynolds number in
small diameter tubes” Heat transfer Engineering, 2003, vol. 24, n°3, pp.
4-16.
[4] Apurba Layek, J. S. Saini and S. C. Solanki, “Heat transfer and friction
characteristics for artificially roughened ducts with compound
turbulators”, 2007, International Journal of Heat and Mass Transfer,,
vol. 50, pp. 4845-4854.
[5] C. F. Colebrook, “Turbulent flow in pipes, with particular references to
the transition region between the smooth and rough pipe laws” Journal
of the Institute of Civil Engineers, 1938, Vol. 11, 133.
[6] J. Nikuradse, “Laws of Flow in rough Pipes” PHD Thesis, 1950, NACA
Technical Memorandum 1292
[7] L. Moody, “Friction Factors of pipe flow” Transaction of the ASME,
Vol. 66, 671.
[8] P. Wu and W. A. Little, “Measurement of the heat transfer
characteristics of gas flow in fine channel heat exchangers used for
micro miniature refrigerators” Cryogenics, 1984, pp. 415-420.
[9] T. M. Adams, S. I. Abdel-Khalik, S. M. Jeter, Z. H. Qureshi,
“Applicability of Traditional Turbulent Single-Phase forced convection
Correlations to non-circular microchannels”, International Journal of
Heat and Mass Transfer, 1999, vol. 42, no 23, pp. 4411-4415.
[10] S. Reynaud, F. Debray, J. P. Franc, T. Maitre, “Hydrodynamics and
Heat Transfer in Two-Dimensional Minichannels” International Journal
of Heat and Mass Transfer, 2005, vol. 48, no. 15, pp. 3197-3211.
[11] B. Xu, K. T. Ooi, N. T. Wong, W. K. Choi, “Experimental investigation
of flow friction for liquid flow in microchannels”, Int. Commun. Heat
Mass Transfer,2000, vol 27, pp. 1165–1176.
[12] R. Baviere, M. F. Marinet, S. Le Person et M. Favre-Marinet, “Effects
on heat transfer measurements in microchannel flows” Int. J. Heat Mass
Transfer, 2006, vol. 49, n° 1, pp. 3325-3337.
[13] G. P. Celata, M. Cumo, V. Marconi, S. J. Mc Phil and G. Zummo,
«Microtube liquid single-phase heat transfer in laminar flow»
International Journal of Heat and Mass Transfer, 2006, Vol.49, pp.
3538-3546.
[14] V. Gnielinski, “New equations for heat and mass transfer in turbulent
pipe and channel flow” Int. Chem. Eng., 1976, vol. 16, no 2, pp. 359-
368.
[15] J. Thaine, J. P. Petit, “Transferts thermiques : Mécanique des fluides
anisothermes» 1ère edition, Dunod, 1989.
[16] Chen Yong ping, Zhang Chengbin, Shi Mingheng, Wu Jiafeng. “Threedimensional
numerical simulation of heat and fluid flow in noncircular
microchannel heat sinks” International Communication in Heat and
Mass Transfer, 2009, vol. 36, no 9, pp 17-20.