Page 120 - Process Equipment and Plant Design Principles and Practices by Subhabrata Ray Gargi Das

4.7 Design illustration 117

N t Number of tubes ( )

h o De
Nu De Nusselt number based on De and shell-side fluid thermal conductivity k s ¼
k s
p design Design pressure
Pr s Prandtl number of shell-side fluid ( )
P T Tube pitch (mm)
Q Heat transfer rate (W)
m c C p;c T h;in T h;out ( )
R ¼ ¼
m h C p;h T c;out T c;in
R d Dirt factor
DeG s Reynolds number for shell-side flow based on equivalent shell diameter ( )
Re De ¼
m s
R w Tube wall resistance
T c;out T c;in
( )
S ¼
T h;in T c;in
t Tube wall thickness (mm)
t IB Thickness of impingement baffle (mm)
t channel Thickness of the flat channel cover (mm)
T Temperature ( C)

DT LMTD,counterflow Log mean temperature difference ( C)

TS Tube sheet thickness (mm)
u s Shell-side flow velocity (m/s)
u t Tube-side velocity (m/s)
u s;in Velocity of the entering shell-side fluid (m/s)
U Overall heat transfer coefficient calculated from Eq. (3.3) (W/m 2 C)
U D Design overall heat transfer coefficient (W/m 2 C)
W IB Width of impingement baffle (mm)
2
p ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
X ¼ ð R þ 1Þ ln ð f 1 SÞ= 1 RSÞg
ð

p ffiffiffiffiffiffiffiffiffiffiffiffiffi
Y ¼ R 1Þ ln 2 S R þ 1 p ð ffiffiffiffiffiffiffiffiffiffiffiffiffi
R 2 þ 1Þ

ð
2 S R þ 1 þ ð R 2 þ 1Þ
Dp Core pressure drop
c
Dp a Pressure drop due to acceleration
Dp e Exit pressure loss
Dp in Entry pressure loss
Dp s Shell-side pressure drop excluding nozzle
Dp t Tube-side pressure drop excluding nozzle
Greek symbols
b Flow area ratio with subscript ‘in’ and ‘e’ as contraction ratio at inlet and expansion
ratio at exit
3
r m Mean fluid density (kg/m )
3
r t Average density of tube-side fluid (kg/m )
3
r s Average density of shell-side fluid (kg/m )
3
r s;in Density of the entering shell-side fluid (kg/m )
h p Pump efficiency ( )
m s Dynamic viscosity of shell-side fluid