Thermal Food Processing

Ohmic Heating for Food Processing 463
RfP Parallel resistance of fluid (Ω)
RfS Serial resistance of fluid (Ω)
RpP Parallel resistance of particles (Ω)
S Dissolved solids content (kg·m –3 )
T0p Initial temperature of the particle (K)
Tair Temperature of the air surrounding the walls of the heater (K)
Tf Fluid temperature (K)
Tp Particle temperature (K)
Tps Temperature at the surface of the solid particle (K)
Tref Reference temperature (K)
U Overall heat transfer coefficient (W·m –2 ·K –1 )
V Voltage (V)
Vf Volume of the fluid (m3 )
Vp Volume of the particle (m3 )
Vsys Volume of the relevant part of the system (m3 )
Vsys Volume of the system between the electrodes (m3 )
Z Dependence on temperature of D value (K)
hfp Fluid–particle heat transfer coefficient (W·m –2 ·K –1 )
I Node number (–)
k Frequency constant (sec –1 )
k0 Preexponential factor (sec –1 )
kf Fluid thermal conductivity (W·m –1 ·K –1 )
kp Particle thermal conductivity (W·m –1 ·K –1 )
kx Thermal conductivity in the x direction (W·m –1 ·K –1 )
ky Thermal conductivity in the y direction (W·m –1 ·K –1 )
lfP Length of parallel fluid (m)
lfS Length of serial fluid (m)
lpP Length of parallel particles (m)
m Temperature coefficient (S·m –1 ·K –1 )
mf Temperature coefficient of the fluid (S·m –1 ·K –1 )
mp Temperature coefficient of the particle (S·m –1 ·K –1 )
n Flow behavior index (–)
n Time step index (–)
Unit vector normal to the surface of the tube’s wall (–)
np Number of solid particles in the considered volume (–)
r Radial coordinates (–)
t Time (sec)
Mean fluid velocity profile in the axial direction (m·sec –1 �
n
vz )
w Tube’s wall (–)
x, y Space coordinates (–)
z Axial coordinates (–)