THE EFFECTS OF LONGITUDINAL RIBS ON ENTROPY GENERATION FOR LAMINAR FORCED CONVECTION IN A MICROCHANNEL

Abstract

This paper deals with fluid flow, heat transfer and entropy generation in an internally ribbed microchannel. Mass, momentum and energy equations for constant heat flux boundary condition are solved using the finite volume method. Average Nusselt number and Fanning friction factor are reported as a function of rib height at different Reynolds numbers. The effects of non-dimensional rib height, wall heat flux and the Reynolds number on the entropy generation attributed to friction, heat transfer and total entropy generation are explored. The first law indicates that rib height has the great effect on the flow filed and heat transfer. The second law analysis reveals that for any values of Reynolds number and wall heat flux, as rib height grows; the frictional irreversibility increases while, there is a rib height which provides the minimum heat transfer irreversibility . It is found that the optimum rib height with the minimum total entropy generation rate depends on Reynolds number and wall heat flux.

Dates

  • Submission Date2013-09-20
  • Revision Date2014-07-03
  • Acceptance Date2014-07-06
  • Online Date2014-10-05

DOI Reference

10.2298/TSCI130920110S

References

  1. Garimella, S.V. , Sobhan , C.B., Transport in microchannels- a critical review, Annu. Rev. Heat Transfer 13 (2003), pp.1-50.
  2. Hassan, I., Phutthavong , P., Abdelgawad, M., Microchannel heat sinks: an overview of the state-of-the-art, Microscale Thermal Engineering 8 (2004), pp.183-205.
  3. Adham, A.M., Ghazali, N.M., Ahmad, R., Thermal and hydrodynamic analysis of microchannel heat sinks: A review, Renewable and Sustainable Energy Reviews 21 (2013), pp.614-622.
  4. Bejan, A., Entropy Generation Through Heat and Fluid Flow, Wiley, New York, 1982.
  5. Bejan, A., Entropy Generation Minimization, CRC Press, Boca Raton, FL, 1996.
  6. Bejan, A., Second-law analysis in heat transfer and thermal design, Advances in Heat Transfer 15 (1982), pp. 1-58.
  7. Hooman, K., Entropy generation for microscale-forced convection: Effects of different thermal boundary conditions, velocity slip, temperature jump, viscous dissipation, and duct geometry, International Communications in Heat and Mass Transfer 34 (2007), pp.945-957.
  8. Kuddusi, L., First and second law analysis of fully developed gaseous slip flow in trapezoidal silicon microchannels considering viscous dissipation effect, International Journal of Heat and Mass Transfer 54 (2011), pp. 52-64.
  9. Hung, Y. M., Viscous dissipation effect on entropy generation for non-Newtonian fluids in microchannels, International Communications in Heat and Mass Transfer 35 (2008), pp. 1125-1129.
  10. Singh, P. K., et al., Entropy generation due to flow and heat transfer in nanofluids, International Journal of Heat and Mass Transfer 53 (2010), pp. 4757-4767.
  11. Tabrizi, A. Sh., Seyf, H. R., Analysis of entropy generation and convective heat transfer of Al2O3 nanofluid flow in a tangential micro heat sink, International Journal of Heat and Mass Transfer 55(2012),15-16, pp. 4366-4375
  12. Ibáñeza, G., Cuevasb, S., Entropy generation minimization of a MHD (magnetohydrodynamic) flow in a microchannel, Energy 35 (2010), pp. 4149-4155.
  13. Abbassi, H., Entropy generation analysis in a uniformly heated microchannel heat sink, Energy 32 (2007), pp. 1932-1947.
  14. Yari, M., Second-law analysis of flow and heat transfer inside a microannulus, International Communications in Heat and Mass Transfer 36 (2009),pp. 78-87.
  15. Guo, J. , Xu, M. , Cheng, L. , Second law analysis of curved rectangular channels, International Journal of Thermal Sciences50 (2011), 5, pp.760-768
  16. Guo, J., et.al, The effect of temperature-dependent viscosity on entropy generation in curved square microchannel, Chemical Engineering and Processing: Process Intensification, 52 (2012), pp.85-91.
  17. Guo, J., et.al, Viscous dissipation effect on entropy generation in curved square microchannels, Energy 36 (2011), pp. 5416-5423.
  18. Tso, C.P., Mahulikar, S.P., The use of the Brinkman number for single phase forced convective heat transfer in microchannels, International Journal of Heat and Mass Transfer 41(1998),12, pp. 1759-1769.
  19. Tso, C.P., Mahulikar, S.P., The role of the Brinkman number in analyzing flow transitions in microchannels, International Journal of Heat and Mass Transfer 42 (1999), 10, pp. 1813-1833.
  20. Dang, T., Teng, J.T., Chu, J.Ch., A study on the simulation and experiment of a microchannel counter-flow heat exchanger, Applied Thermal Engineering 30 (2010), 14-15, pp. 2163-2172.
  21. Dang, T., Teng, J.T., Chu, J.Ch., Influence of gravity on the performance index of microchannel heat exchangers - Experimental investigations, World Congress on Engineering, London, United Kingdom, 2011, pp. 2094- 2099.
  22. Patankar, S.V., Numerical Heat Transfer and Fluid Flow, Hemisphere, Washington, D.C., 1980
  23. Liu, Ch., et al., Experimental investigations on liquid flow and heat transfer in rectangular microchannel with longitudinal vortex generators, International Journal of Heat and Mass Transfer 54 (2011), 13-14, pp. 3069-3080.
  24. Foong, A. J.L., Ramesh, N., Chandratilleke, T. T., Laminar convective heat transfer in a microchannel with internal longitudinal fins, International Journal of Thermal Sciences 48 (2009),10, pp.1908-1913.
  25. Hesselgreaves, J.E, Rationalisation of second law analysis of heat exchangers, International Journal of Heat Mass Transfer 43 (2000),22, pp. 4189-4204.