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Radial T Profile Across Wall Separating Hot & Cold Fluids
1
D i
D o
T i
T c
T o
T h T w h
T w c
e n d v ie wo f s lic e
( in c lu d in go u te r s h e ll)
r
r i r o r
resi
stan
ce #
1
resi
stan
ce #
2
resi
stan
ce #
3
dL
o b liq u e v ie wo f s lic e o f in n e rp ip e w a ll
Sieder-Tate Equation(hi for turbulent flow inside pipes)
Nu Re Pr
1/30.8 0.14
0.023 pi ii i i i
i i i iwN N N
ch D GD
k k
Di
G
i i
Q mG v
S S
Shell-and-Tube Hxer
Example:* A steel mill needs to cool 3,000 gal/hr of a dilute acid from 200F to 130F using 5,000 gal/hr of 80F river water. A shell-and-tube heat exchanger is available (see description below). Determine if this heat exchanger is sufficient for this task.
Description of available heat exchanger:
type: 1-2
tubes: 158 1-inch, 14BWG stainless tubes, 16 ft long, stacked in 1¼ inch square pitch
baffles: 25% with 6 inch pitch
shell: 20 inch inside diameter, mild steel
* Shell&tube hxer example.mcd
Hxer Example Problem
BWG = Babcock & Wilcox Gauge
Example:* A steel mill needs to cool 3,000 gal/hr of a dilute acid from 200F to 130F using 5,000 gal/hr of 80F river water. A shell-and-tube heat exchanger is available (see description below). Determine if this heat exchanger is sufficient for this task.
Description of available heat exchanger:
type: 1-2
tubes: 158 1-inch, 14BWG stainless tubes, 16 ft long, stacked in 1¼ inch square pitch
baffles: 25% with 6 inch pitch
shell: 20 inch inside diameter, mild steel
* Shell&tube hxer example.mcd
Hxer Example Problem
Tube Pitch
Tube Pitch: the Dimension
Example:* A steel mill needs to cool 3,000 gal/hr of a dilute acid from 200F to 130F using 5,000 gal/hr of 80F river water. A shell-and-tube heat exchanger is available (see description below). Determine if this heat exchanger is sufficient for this task.
Description of available heat exchanger:
type: 1-2
tubes: 158 1-inch, 14BWG stainless tubes, 16 ft long, stacked in 1¼ inch square pitch
baffles: 25% with 6 inch pitch
shell: 20 inch inside diameter, mild steel
* Shell&tube hxer example.mcd
Hxer Example Problem
Baffle Pitch, P
sh e ll- s id e f lo w
tu b es id e
f lo w
P b a ff le s
tu b e sh e e ts
Baffle Plate & Baffle Window(25% Baffle Window)
Ds
end view side view
baffle window
25%baffleplate
Ds
4
holesfortubes
e b cG G G 2Kg
[ ]m s
bb
mG
S
c
c
mG
S
Effective Mass Velocity
2 2
area of blue region
4 4s o
b b bD D
S f N
Flow Area in Baffle Window
1 oc s
DS PD
p
total area = PDs
length of unit cell = p (tube pitch)
length which is open = p-Do
fraction open = (p-Do)/p = 1 - Do/p
Flow Area for Cross Flow
end viewside view
p
P
widestrow of
tubes
area forcross-flow(shaded yellow)
DsDo
Multipass Construction
sh e ll- s id e f lo w
tu b es id e
f lo w
P b a ff le s
tu b e sh e e ts
sh e ll- s id e f lo w
tu b es id e
f lo w
tu b e sh e e tssh e ll- s id e f lo w
tu b es id e
f lo w
tu b e sh e e ts
1 shell pass
1 tube pass
1 shell pass
2 tube passes
2 shell passes
2 tube passes
1-1 Hxer
1-2 Hxer
2-2 Hxer
