عنوان مقاله [English]
Due to their high thermal effectiveness, good flow distribution and ease of sanitation, plate heat exchangers (PHEs) are widely used for continuous pasteurization of liquid food products. Since most food products in this research are non-Newtonian fluids, flow behavior in various chevron angles of non–Newtonian power law fluids is studied by means of 2D Computational Fluid Dynamics (CFD). For this purpose, aqueous solutions of carboxy-methyl-cellulose (CMC) at different weight concentrations, ranging from 0.5 % to 2% and 10≤Reg≤300 held at a constant temperature of 20oC were considered as operating conditions. To generate geometry and mesh, solve governing equations by finite volume method and analyze CFD results, software applications Gambit 2.0 and FLUENT 6.0.12 were used respectively. Analyses over the relationship between Reynolds number, fanning friction factor and rheological parameters of the fluid and chevron angles of the plates for different concentrations of CMC have been performed. Predictions of CFD calculations were compared to the experimental data, and these results showed a very good agreement.
 Manglik R.M. & Ding J. “Laminar flow heat transfers to viscous power- law fluids in double-sine ducts”, lnt. J. Heat Mass Transfer, Vol. 40, No. 6, pp. 1379-1390, 1996.
 Metwally H.M. & Manglik R.M. “Enhanced heat transfer due to curvature-induced lateral vortices in laminar flows in sinusoidal corrugated-plate channels”, International Journal of Heat and Mass Transfer, Vol. 47, pp. 2283–2292, 2004.
 Bereiziat D. & Devienne R. “Experimental characterization of newtonian and non-newtonian fluid flows in corrugated channels”, International Journal of Engineering Science, Vol. 37, pp. 1461-1479, 1999.
 Perona P. “An experimental investigation of laminar–turbulent transition in complex fluids”, Journal of Food Engineering, Vol. 60, pp. 137–145, 2003.
 Fernandes S.C., Dias R.P., Nobrega J.M., Alfonso I.M., Melo L.F. & Maia J.M. “Thermal behavior of stirred yoghurt during cooling in plate heat exchanger”, Journal of food Engineering, Vol. 76, pp. 433-439, 2006.
 Mehrabian M.A. & Poulter R. “Hydrodynamic and thermal characteristics of coruugated channels: computational approach”, Applied Mathematical, Vol. 24, pp. 304-312, 2000.
 Fernandes S.C., Dias R.P., Nobrega J.M. & Maia J.M. “Effect of corrugated angle on the hydrodynamic behavior of power-law fluids during a flow in plate heat exchangers”, 5th International Congress on Enhanced, Comapact and Ultra-Compact heat exchangers; Science, Engineering and Technology, Hoboken, USA, CHE2005-65, pp. 491-495, 2005.
 Fernandes S.C., Dias R.P., Nobrega J.M., Alfonso I.M., Melo L.F. & Maia J.M. “Laminar flow in chevron-type plate heat exchangers: CFD analysis of tortuosity, shape factor and friction factor”, Chemical Engineering and processing, Vol. 46, pp. 825-833, 2007.
 Delpelace F. & Leuliet J.C. “Generalized reynolds number for the flow of power law fluids in cylindrical ducts of arbitrary cross-section”, Chem Eng Journal, Vol. 56, pp. 33-37, 1995.
 Metzner A.B & Reed J.C. “Flow of non-newtonian fluids-correlation of the laminar, transition, and turbulent-flow regions”, A.l.Ch.E. Journal, Vol. 1, pp. 434-440,1995.
 Peixinho J., Desaubry C. & Lebouché M. “Heat transfer of a non-newtonian fluid (carbopol aqueous solution) in transitional pipe flow”, International Journal of Heat and Mass Transfer, Vol. 51, Issues 1-2, pp. 198-209, 2008.
 Telis-Romero J. Thomaz C.E.P., Bernardi M., Telis V.R.N & Gabas A.L., “Rheological properties and fluid dynamic of egg yolk”, Journal of food engineering, Vol. 74, pp. 191-197, 2006.
 Saunders E.A.D. “Heat exchangers, selection, design and construction”, Longman Scientific &Technical, pp . 367-8, 2002.