Abstract
In this paper, forced convection in a rectangular duct subjected to microwave heating is investigated. Three types of non-Newtonian liquids flowing through the duct are considered, specifically, apple sauce, skim milk, and tomato sauce. A finite difference time domain method is used to solve Maxwell’s equations simulating the electromagnetic field. The three-dimensional temperature field is determined by solving the coupled momentum, energy, and Maxwell’s equations. Numerical results show that the heating pattern strongly depends on the dielectric properties of the fluid in the duct and the geometry of the microwave heating system.
Similar content being viewed by others
Abbreviations
- A :
-
area (m2)
- C p :
-
specific heat capacity (J/(kg K))
- c :
-
phase velocity of the electromagnetic propagation wave (m/s)
- E :
-
electric field intensity (V/m)
- f :
-
frequency of the incident wave (Hz)
- h :
-
effective heat transfer coefficient (W/(m2 K))
- H :
-
magnetic field intensity (A/m)
- L :
-
standard deviation of temperature (°C)
- k :
-
thermal conductivity (W/(m K))
- m :
-
fluid consistency coefficient, (Pa sn)
- n :
-
flow behavior index
- N t :
-
number of time steps
- p :
-
pressure (Pa)
- q :
-
electromagnetic heat generation intensity (W/m3)
- Q :
-
volume flow rate (m3/s)
- T :
-
temperature (°C)
- t :
-
time (s)
- tan δ:
-
loss tangent
- w :
-
velocity component in the z direction (m/s)
- W :
-
width of the cavity (m)
- ZTE :
-
wave impedance (Ω)
- η:
-
apparent viscosity (Pa s)
- ε:
-
electric permittivity (F/m)
- ɛ′:
-
dielectric constant
- ɛ′′:
-
effective loss factor
- λ g :
-
wave length in the cavity (m)
- μ:
-
magnetic permeability (H/m)
- ρ:
-
density (kg/m3)
- σ:
-
electric conductivity (S/m)
- τ:
-
instantaneous value
- ∞:
-
ambient condition
- 0:
-
free space, air
- inc:
-
incident plane
- in:
-
inlet
- x, y, z :
-
coordinate system of the applicator
- X, Y, Z :
-
coordinate system of the microwave cavity
References
Dibben DC, Metaxas AC (1995) Time domain finite element analysis of multimode microwave applicators loaded with low and high loss materials. In: Proceedings of the international conference on microwave and high frequency heating, vol 1–3, no. 4
De Pourcq M (1985) Field and power density calculation in closed microwave system by three-dimensional finite difference. IEEE Proc 132(11):361–368
Jia X, Jolly P (1992) Simulation of microwave field and power distribution in a cavity by a three dimensional finite element method. J Microw Power Electromagn Energy 27(1):11–22
Anantheswaran RC, Liu L (1994) Effect of viscosity and salt concentration on microwave heating of model non-Newtonian liquid foods in a cylindrical container. J Microw Power Electromagn Energy 29(2):119–126
Zhang Q, Jackson TH, Ungan A (2000) Numerical modeling of microwave induced natural convection. Int J Heat Mass Transf 43:2141–2154
Webb JP, Maile GL, Ferrari RL (1983) Finite element implementation of three dimensional electromagnetic problems. IEEE Proc 78:196–200
Ayappa KG, Davis HT, Davis EA, Gordon J (1992) Two-dimensional finite element analysis of microwave heating. AIChE J 38:1577–1592
Liu F, Turner I, Bialkowski M (1994) A finite-difference time-domain simulation of power density distribution in a dielectric loaded microwave cavity. J Microw Power Electromagn Energy 29(3):138–147
Zhao H, Turner IW (1996) An analysis of the finite-difference time-domain method for modeling the microwave heating of dielectric materials within a three-dimensional cavity system. J Microw Power Electromagn Energy 31(4):199–214
Zhang H, Taub AK, Doona IA (2001) Electromagnetics, heat transfer and thermokinetics in microwave sterilization. AIChE J 47:1957–1968
Zhang H, Datta AK (2000) Coupled electromagnetic and thermal modeling of microwave oven heating of foods. J Microw Power Electromagn Energy 35(2):71–85
Patankar SV (1980) Numerical heat transfer and fluid flow. Hemisphere, New York
Cheng DK (1992) Field and wave electromagnetics, 2nd edn. Addison-Wesley, New York
Mur G (1981) Absorbing boundary conditions for the finite difference approximation of the time domain electromagnetic field equations. IEEE Trans Electromag Compat EC-23:377–382
Yee KS (1966) Numerical solution of initial boundary value problem involving Maxwell’s equations in isotropic media. IEEE Trans Antennas Propagation 14:302–307
Kunz KS, Luebbers R (1993) The finite difference time domain method for electromagnetics. CRC, Boca Raton
Zhang Q (1998) Numerical simulation of heating of a containerized liquid in a single-mode microwave cavity. MS thesis, Indiana University-Purdue University at Indianapolis
Acknowledgements
The authors acknowledge with gratitude a USDA grant that provided support for this work and the assistance of the Food Rheology Laboratory at North Carolina State University. The calibrations of the fluid consistency coefficients and the flow behavior indexes for the non-Newtonian liquids considered in this study by Ms. S. Ramsey are greatly appreciated.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Zhu, J., Kuznetsov, A.V. & Sandeep, K.P. Numerical simulation of forced convection in a duct subjected to microwave heating. Heat Mass Transfer 43, 255–264 (2007). https://doi.org/10.1007/s00231-006-0105-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00231-006-0105-y