Tham khảo tài liệu 'two phase flow phase change and numerical modeling part 17', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 470 Two Phase Flow Phase Change and Numerical Modeling Particularly if is the energy density of a fluid Landau Lifshitz 1987 e e p p v2 2 the classical form of the energy conservation law results the physical significances of e and p are given in Landau Lifshitz 1987 . Several numerical investigations of the nanofluid heat transfer have been accomplished in Maiga et al. 2005 2004 Patankar 1980 . Akbarnia and Behzadmehr Akbarnia Behzadmehr 2007 reported a Computational Fluid Dynamics CFD model based on single phase model for investigation of laminar convection of water-AhOs nanofluid in a horizontal curved tube. In their study effects of buoyancy force centrifugal force and nanoparticle concentration have been discussed. In that follows we shall perform numerical studies on the nanofluid heat transfer waterbased nanofluids AI2O3 with 10 nm particle-sizes in a coaxial heat exchanger. The detailed turbulent flow field for the single-phase flow in a circular tube with constant wall temperature can be determined by solving the volume-averaged fluid equations as follows i. continuity equations 88 b v o 91 ii. momentum equation 88 a in the form v vv P B 92 where we supposed that Harvey 1966 Albeverio Hoegh-Krohn 1974 Q P B 93 p T and B having the significances from Fard et al. 2009 iii. energy equation 90 in the form H VCPT fc T c VT 94 where H is the enthalpy Cp is the specific heat capacity and T is the temperature field. In order to solve above-mentioned equations the thermo physical parameters of nanofluids such as density heat capacity viscosity and thermal conductivity must be evaluated. These parameters are defined as follows i. density and heat capacity. The relations determinate by Pak si cho Pak cho 1998 have the form 1 p 95 cn l C c 96 ii. thermal conductivity. The effective thermal conductivity of a mixture can be calculated by using relation 43 k k 1 -5----- 97 kf kfơ Heat Transfer in Nanostructures Using the Fractal Approximation of Motion 471 .
