ABSTRACT
Conjugate heat transfer in a finned channel with equally spaced fins placed transversely to the flow direction following in-line and staggered arrangements is evaluated. The fins and channel walls are heat-conducting and are fully coupled to a turbulent fluid flow problem. The hydrodynamic and thermal effects of the fin blockage ratio, fin angle, and flow velocity were investigated. The simulations show that the fin arrangement is of paramount importance on the performance of the heat exchanger: the staggered fin configuration provided lower pressure drop and higher heat transfer rate than the in-line fin arrangement for different flow conditions.
Nomenclature
c | = | specific heat |
Cp | = | pressure coefficient |
Dh | = | hydraulic diameter |
Dij | = | strain rate tensor |
= | deviatoric strain rate tensor | |
h | = | global heat convection coefficient |
ha | = | minimum distance between fins |
hf | = | fin height |
hx | = | local heat transfer coefficient |
H | = | channel height |
Ha | = | distance between a fin and the opposite wall |
Hd | = | downstream channel height |
Hu | = | upstream channel height |
I | = | turbulence intensity |
k | = | thermal conductivity |
L | = | channel length |
Ld | = | downstream channel length |
Lu | = | upstream channel length |
N | = | number of fins per wall |
Nux | = | local Nusselt number |
Nu | = | global Nusselt number |
ṁ | = | mass flow rate |
p | = | pressure |
q | = | heat flux |
Re | = | Reynolds number |
rf | = | fin blockage ratio |
s | = | step height |
sij | = | deviatoric stress tensor |
Sf | = | distance between two fins |
Stx | = | local Stanton number |
t | = | time |
tb | = | fin base thickness |
tf | = | fin tip thickness |
tw | = | wall thickness |
T | = | temperature |
ui | = | velocity components |
ue | = | entrance velocity |
xi | = | coordinate components |
Greek letters | = | |
β | = | fin angle |
δij | = | Kronecker delta |
μ | = | viscosity |
ρ | = | specific mass |
Subscripts | = | |
avg | = | average |
e | = | channel inlet |
f | = | fluid |
i,j | = | coordinate index |
s | = | solid |
0 | = | smooth channel |
Nomenclature
c | = | specific heat |
Cp | = | pressure coefficient |
Dh | = | hydraulic diameter |
Dij | = | strain rate tensor |
= | deviatoric strain rate tensor | |
h | = | global heat convection coefficient |
ha | = | minimum distance between fins |
hf | = | fin height |
hx | = | local heat transfer coefficient |
H | = | channel height |
Ha | = | distance between a fin and the opposite wall |
Hd | = | downstream channel height |
Hu | = | upstream channel height |
I | = | turbulence intensity |
k | = | thermal conductivity |
L | = | channel length |
Ld | = | downstream channel length |
Lu | = | upstream channel length |
N | = | number of fins per wall |
Nux | = | local Nusselt number |
Nu | = | global Nusselt number |
ṁ | = | mass flow rate |
p | = | pressure |
q | = | heat flux |
Re | = | Reynolds number |
rf | = | fin blockage ratio |
s | = | step height |
sij | = | deviatoric stress tensor |
Sf | = | distance between two fins |
Stx | = | local Stanton number |
t | = | time |
tb | = | fin base thickness |
tf | = | fin tip thickness |
tw | = | wall thickness |
T | = | temperature |
ui | = | velocity components |
ue | = | entrance velocity |
xi | = | coordinate components |
Greek letters | = | |
β | = | fin angle |
δij | = | Kronecker delta |
μ | = | viscosity |
ρ | = | specific mass |
Subscripts | = | |
avg | = | average |
e | = | channel inlet |
f | = | fluid |
i,j | = | coordinate index |
s | = | solid |
0 | = | smooth channel |