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AC 26/02/2015
Item no. 4.66
Heat Exchanger Data Book
CHC603 Heat Transfer Operation – II
&
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Contents
I
Formulae, graphs and tables
1
1 Shell and Tube Heat Exchanger
1.1 Log Mean Temperature difference . . . . . . . . . . .
1.1.1 Correction factor . . . . . . . . . . . . . . . .
1.2 Heat transfer through tubes . . . . . . . . . . . . . .
1.3 Shell-side heat-transfer coefficient(Kern’s Method) . .
1.4 Bell’s method for HTC shell side . . . . . . . . . . .
1.4.1 HTC cross flow . . . . . . . . . . . . . . . . .
1.4.2 Fn , tube row correction factor . . . . . . . . .
1.4.3 Fw , window correction factor . . . . . . . . . .
1.4.4 Fb , bypass correction factor . . . . . . . . . .
1.4.5 FL , Leakage correction factor . . . . . . . . .
1.5 Pressure Drop in shell . . . . . . . . . . . . . . . . .
1.5.1 Cross-flow zones . . . . . . . . . . . . . . . . .
1.5.2 ∆Pi ideal tube bank pressure drop . . . . . .
1.5.3 Fb0 , bypass correction factor for pressure drop
1.5.4 FL0 , leakage factor for pressure drop . . . . . .
1.5.5 Window-zone pressure drop . . . . . . . . . .
1.5.6 End zone pressure drop . . . . . . . . . . . . .
1.5.7 Total shell-side pressure drop . . . . . . . . .
1.5.8 Shell and bundle geometry . . . . . . . . . . .
1.6 Wills-Johnston Method . . . . . . . . . . . . . . . . .
1.6.1 Streams and flow areas . . . . . . . . . . . . .
1.6.2 Flow resistances . . . . . . . . . . . . . . . . .
1.6.3 Total shell-side pressure drop . . . . . . . . .
1.7 Fouling factor . . . . . . . . . . . . . . . . . . . . . .
1.8 Tube data . . . . . . . . . . . . . . . . . . . . . . . .
2 Plate Heat Exchanger
2.1 Plate . . . . . . . . . . . . . . . . . . . . . .
2.2 Heat transfer coefficient . . . . . . . . . . .
2.2.1 Number of Transfer Units (NTU) . .
2.2.2 Correction factor, Ft . . . . . . . . .
2.3 Pressure drop . . . . . . . . . . . . . . . . .
2.3.1 Pressure drop in flow through plates
2.3.2 Pressure drop in flow through port .
2.4 Plate sizes . . . . . . . . . . . . . . . . . . .
iii
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3
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21
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24
University of Mumbai
CHC603
3 Condenser Design
3.1 HTC in Vertical condenser . . . . . . . . .
3.2 HTC in Horizontal Condenser . . . . . . .
3.3 Condensation with subcooling . . . . . . .
3.4 Condensation with desuperheating . . . .
3.5 Condensation in vertical tubes with vapour
3.6 Condensation outside horizontal tubes . .
Heat Exchanger Data Book
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27
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4 Reboiler Design
4.1 Nucleate Boiling . . . . . . . . . . . . . . . . . . . . . . . .
4.1.1 The Forster-Zuber correlation . . . . . . . . . . . .
4.1.2 The Mostinski correlation . . . . . . . . . . . . . .
4.1.3 The Cooper correlation . . . . . . . . . . . . . . . .
4.1.4 The Stephan-Abdelsalam correlation . . . . . . . .
4.1.5 Boiling mixtures . . . . . . . . . . . . . . . . . . .
4.1.6 Convective effects in tube bundles . . . . . . . . . .
4.2 Critical heat flux . . . . . . . . . . . . . . . . . . . . . . .
4.2.1 Mostinski correlation . . . . . . . . . . . . . . . . .
4.3 Two Phase Flow . . . . . . . . . . . . . . . . . . . . . . .
4.3.1 Pressure drop correlations . . . . . . . . . . . . . .
4.4 Convective Boiling in Tubes . . . . . . . . . . . . . . . . .
4.4.1 Heat transfer coefficient . . . . . . . . . . . . . . .
4.4.2 Critical heat flux . . . . . . . . . . . . . . . . . . .
4.5 Film Boiling . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.1 Heat transfer coefficient . . . . . . . . . . . . . . .
4.6 Design equations . . . . . . . . . . . . . . . . . . . . . . .
4.6.1 Number of nozzles . . . . . . . . . . . . . . . . . .
4.6.2 Shell diameter . . . . . . . . . . . . . . . . . . . . .
4.7 Frictional losses in pipe . . . . . . . . . . . . . . . . . . . .
4.7.1 Friction factor . . . . . . . . . . . . . . . . . . . . .
4.7.2 Pressure drop in pipe . . . . . . . . . . . . . . . . .
4.7.3 Maximum gas/vapour velocity in tubes . . . . . . .
4.7.4 Maximum velocity of liquids in tubes . . . . . . . .
4.7.5 Maximum velocity of two-phase flow in tubes/pipe
4.8 Design of Vertical Thermosyphon Reboiler . . . . . . . . .
4.8.1 Pressure balance . . . . . . . . . . . . . . . . . . .
4.8.2 Sensible heating zone . . . . . . . . . . . . . . . . .
4.8.3 Mist flow limit . . . . . . . . . . . . . . . . . . . .
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II
Data Sheet
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downflow
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45
iv
Part I
Formulae, graphs and tables
1
Chapter 1
Shell and Tube Heat Exchanger
1.1
Log Mean Temperature difference
For counter current flow,
∆Tlm =
(Thin − Tcout ) − (Thout − Tcin )
Thin − Tcout
ln
Thout − Tcin
∆Tm = Ft ∆Tlm
1.1.1
(1.1)
(1.2)
Correction factor
For one shell pass and two or more even tube passes shell and tube heat exchanger,
p
1
−
S
(R2 + 1)ln
1 − RS

Ft =

p
2
2 − S R + 1 − (R + 1)

(R − 1) ln 
p
2
2 − S R + 1 + (R + 1)
(1.3)
where,
Tin − Tout
tout − tin
tout − tin
S=
Tin − tin
R=
T
t
Th
Tc
=
=
=
=
Shell side temperature
Tube side temperature
hot fluid temperature
cold fluid temperature
3
(1.4)
(1.5)
University of Mumbai
CHC603
4
Heat Exchanger Data Book
University of Mumbai
CHC603
5
Heat Exchanger Data Book
University of Mumbai
CHC603
Heat Exchanger Data Book
Figure 1.1: LMTD Correction factor (1 Shell pass; 3 tube passes)
1.2
Heat transfer through tubes
Seider-Tate and Hausen equations,
for Re ≥ 104
N u = 0.023Re0.8 P r1/3 (µ/µw )0.14
(1.6)
for 2100 < Re ≥ 104
h
i
2/3
1/3
2/3
0.14
N u = 0.116 Re − 125 P r (µ/µw )
1 − (D/L)
(1.7)
N u = 1.86 [ReP r (D/L)]1/3 (µ/µw )0.14
(1.8)
for Re ≤ 2100
1.3
Shell-side heat-transfer coefficient(Kern’s Method)
jH = 0.5 (1 + lB /Ds ) 0.08Re0.6821 + 0.7Re0.1772
(1.9)
where,
jH =
lB
Ds
de
ho de −1/3
Pr
(µ/µw )−0.14
k
= baffle spacing
= shell ID
= equivalent diameter
6
(1.10)
University of Mumbai
CHC603
Heat Exchanger Data Book
Gs de
µ
ṁs
Gs =
As
(pt − do ) Ds lB
As =
pt
Re =
(1.11)
(1.12)
(1.13)
for a square pitch arrangement:
de =
1.27 2
pt − 0.785d2o
do
(1.14)
for an equilateral triangular pitch arrangement:
de =
1.4
1.10 2
pt − 0.917d2o
do
Bell’s method for HTC shell side
hs = hoc Fn Fw Fb FL
hoc
Fn
Fw
Fb
FL
(1.15)
(1.16)
= heat transfer coefficient calculated for cross-flow over an ideal tube bank,
no leakage or bypassing.
= correction factor to allow for the effect of the number of vertical tube rows,
= window effect correction factor,
= bypass stream correction factor,
= leakage correction factor.
1.4.1
HTC cross flow
See section – (1.3)
hoc do
= jH P r1/3
kf
1.4.2
µ
µw
0.14
(1.17)
Fn , tube row correction factor
1. Re > 2000, turbulent; take Fn from Figure 12.32.
2. Re > 100 to 2000, transition region, take Fn = 1.0;
3. Re < 100, laminar region,Fn ∝ (Nc0 )−0.18
where Nc0 is the number of rows crossed in series from end to end of the shell.
1.4.3
Fw , window correction factor
The correction factor is shown in Figure 12.33 plotted versus Rw , the ratio of the number of
tubes in the window zones to the total number in the bundle. For Rw refer section – 1.5.8
7
University of Mumbai
1.4.4
CHC603
Heat Exchanger Data Book
Fb , bypass correction factor
"
Fb = exp −α
Ab
As
1−
2Ns
Ncv
1/3 !#
(1.18)
where,
α
α
Ab
As
Ns
Ncv
=
=
=
=
=
=
1.4.5
1.5 for laminar flow, Re < 100,
1.35 for transitional and turbulent flow Re > 100,
clearance area between the bundle and the shell, refer equation – (1.35),
maximum area for cross-flow,
number of sealing strips encountered by the bypass stream in the cross-flow zone,
the number of constrictions, tube rows, encountered in the cross-flow section.
FL , Leakage correction factor
FL = 1 − βL
Atb + 2Asb
AL
(1.19)
where,
βL
Atb
Asb
AL
=
=
=
=
1.5
1.5.1
a factor obtained from Figure 12.35,
the tube to baffle clearance area, per baffle,
shell-to-baffle clearance area, per baffle,
total leakage area = (Atb + Asb ).
Pressure Drop in shell
Cross-flow zones
∆Pc = ∆Pi Fb0 FL0
8
(1.20)
University of Mumbai
1.5.2
CHC603
Heat Exchanger Data Book
∆Pi ideal tube bank pressure drop
ρu2
∆Pi = 8jt Ncv s
2
µ
µw
−0.14
(1.21)
where,
Ncv = number of tube rows crossed (in the cross-flow region),
us = shell side velocity, based on the clearance area at the bundle equator,
jt
= friction factor obtained from Figure 12.36, at the appropriate Reynolds number,
Re = (ρus do /µ).
1.5.3
Fb0 , bypass correction factor for pressure drop
The correction factor is calculated from the equation used to calculate the bypass correction
factor for heat transfer, equation – (1.18) but with the following values for the constant α,
where,
α = 5 for laminar flow, Re < 100,
α = 4 for transitional and turbulent flow Re > 100
The correction factor for exchangers without sealing strips is shown in Figure 12.37.
9
University of Mumbai
CHC603
Heat Exchanger Data Book
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CHC603
Heat Exchanger Data Book
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FL0 , leakage factor for pressure drop
The factor is calculated using the equation for the heat-transfer leakage-correction factor,
with the values for the coefficient βL taken from Figure 12.38.
1.5.5
Window-zone pressure drop
∆Pw = FL0 (2 + 0.6Nwv )
ρu2z
2
(1.22)
where
uz
uw
Ws
Nwv
√
= the geometric mean velocity, = uw us
= the velocity in the window zone, based on the window area less the area occupied
by the tubes, uw = AWwsρ
= shell-side fluid mass flow, kg/s,
= number of restrictions for cross-flow in window zone, approximately equal to the
number of tube rows.
1.5.6
End zone pressure drop
∆Pe = ∆Pi
Nwv + Ncv
Fb0
Ncv
11
(1.23)
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University of Mumbai
Heat Exchanger Data Book
University of Mumbai
CHC603
Heat Exchanger Data Book
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ðòè
University of Mumbai
1.5.7
CHC603
Heat Exchanger Data Book
Total shell-side pressure drop
∆Ps = 2∆Pe + ∆Pc (Nb − 1) + Nb ∆Pw
where, Nb =
L
lB
L
lB
(1.24)
−1
= Total tube length,
= baffle spacing
1.5.8
Shell and bundle geometry
Bundle diameter
Db = do
Nt
K1
1/n1
(1.25)
where
Nt
Db
do
= number of tubes,
= bundle diameter, mm,
= tube outside diameter, mm.
Table 1.1: Constants for use in equation –
Triangular pitch, PT = 1.25do
No. of passes
1
2
4
6
K1
0.319 0.249 0.175 0.0743
n1
2.142 2.207 2.285 2.499
Square pitch, PT = 1.25do
No. of passes
1
2
4
6
K1
0.215 0.156 0.158 0.0402
n1
2.207 2.291 2.263 2.617
1.25
8
0.0365
2.675
8
0.0331
2.643
Db
− Ds (0.5 − Bc )
2
Db − 2Hb
Ncv =
p0t
Hb
Nwv = 0
pt
Hb =
Hc =
Hb =
Bb =
θb =
Db =
Ds =
p0t =
p0t =
baffle cut height = Ds × Bc , where Bc is the baffle cut as a fraction,
height from the baffle chord to the top of the tube bundle,
bundle cut = Hb /Db ,
angle subtended by the baffle chord, rads,
bundle diameter.
Shell ID.
pt for square pitch,
0.87pt for equilateral triangular pitch.
14
(1.26)
(1.27)
(1.28)
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Heat Exchanger Data Book
ؽ
¾
ܾ
Ü­
Ú·¹«®» ïîòìðò
Þ¿ºA» ¿²¼ ¬«¾» ¹»±³»¬®§
The number of tubes in a window zone Nw is given by:
Nw = Nt × Ra0
(1.29)
where, Ra0 is the ratio of the bundle cross-sectional area in the window zone to the total bundle
cross-sectional area, Ra0 can be obtained from Figure 12.41, for the appropriate bundle cut,
Bb .
The number of tubes in a cross-flow zone Nc is given by
Nc = Nt − 2Nw
2Nw
Rw =
N
t 2
πDs
πd2o
× Ra − Nw
Aw =
4
4
(1.30)
(1.31)
(1.32)
Ra is obtained from Figure 12.41, for the appropriate baffle cut Bc
Atb =
ct πdo
(Nt − Nw )
2
(1.33)
where ct is the diametrical tube-to-baffle clearance; the difference between the hole and tube
diameter, typically 0.8 mm.
cs Ds
Asb =
(2π − θb )
(1.34)
2
where cs is the baffle-to-shell clearance, see Figure – 1.2.
θb can be obtained from Figure 12.41, for the appropriate baffle cut, Bc
Ab = lB (Ds − Db )
15
(1.35)
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Wills-Johnston Method
1.6.1
Streams and flow areas
The bypass flow area
Sbp = B (Ds − Dot + Np δp )
(1.36)
where,
Ds
B
Dot
Np
δp
=
=
=
=
=
Shell ID
central baffle spacing
outer tube limit diameter
number of tube pass partitions aligned with the cross-flow direction
pass partition clearance
Tube-to-baffle leakage flow
St = nt πDo δtb
(1.37)
Ss = πDs δsb
(1.38)
Shell-to-baffle leakage flow
where
nt
δtb
δsb
= number of tubes in bundle
= tube-to-baffle clearance
= shell-to-baffle clearance
16
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Figure 1.2: Typical baffle clearances.
SBW =
2
BDot
(π − θot + sin θot )
− BNp δp
4Ds (1 − 2Bc )
(1.39)
where,
θot = 2 cos
−1
Ds (1 − 2Bc )
Dot
(1.40)
Here, Bc is the fractional baffle cut and θot is expressed in radians.
1.6.2
Flow resistances
The cross-flow resistance The cross-flow resistance is given by the following equation
4aDo Ds Dv (1 − 2Bc ) (PT − Do )−3
ξB =
ṁB Do
µSBW
−b
2
2ρgc SBW
ṁB
=
ṁo
s
ξx ξo
ξy ξB
(1.41)
(1.42)
where
a= 0.061, b= 0.088
a = 0.450, b = 0.267
for square and rotated-square pitch
for triangular pitch
Dv =
Ω1
Ω1 PT2 − Do2
Do
(1.43)
= 1.273 for square and rotated-square pitch
= 1.103 for triangular pitch
The bypass flow resistance The bypass flow resistance is computed as follows:
0.3164Ds
ξCF =
−0.025
1 − 2Bc
ṁo De
+ 2Nss
Ω2 PT
µSbp
2
2ρgc Sbp
17
(1.44)
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ṁCF
=
ṁo
s
Heat Exchanger Data Book
ξx ξo
ξy ξCF
(1.45)
where
Nss = number of pairs of sealing strips
Ω2 = 1.0 for square pitch
= 1.414 for rotated-square pitch
= 1.732 for triangular pitch
De = equivalent diameter for the bypass flow
2Sbp
Ds − Dotl + 2B + Np (B + δp )
ξy = ξw + ξx
1
ξx = 2
√1 + √ 1
ξB
ξCF
De =
(1.46)
(1.47)
(1.48)
The tube-to-baffle leakage flow resistance The flow resistance for the tube-to-baffle
leakage stream is given by the following equation,
0.036Bt /δtb + 2.3 (Bt /δtb )−0.177
ξA =
2ρgc St2
(1.49)
where Bt is the baffle thickness. Flow fraction,
ṁA
=
ṁo
s
ξo
ξA
(1.50)
where, ṁo is total mass flow.
The shell-to-baffle leakage flow resistance The flow resistance for the shell-to-baffle
leakage stream is given by an equation,
0.036Bt /δsb + 2.3 (Bt /δsb )−0.177
ξE =
2ρgc Ss2
s
ṁE
ξo
=
ṁo
ξE
(1.51)
(1.52)
The window flow resistance The window flow resistance is given by
ξw =
1.9 exp (0.6856Sw /Sm )
2ρgc Sw2
s
ṁw
ξo
=
ṁo
ξy
18
(1.53)
(1.54)
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Inlet and outlet baffle spaces The cross-flow resistance in the end spaces is estimated
by the following equation
2 Dotl
B
1+
(1.55)
ξe = 0.5ξx
Be
Ds (1 − 2Bc )
the end baffle spaces. The flow resistance in the end windows is calculated as follows
ξwe =
1.9 exp [0.6856Sw B/(Sm Be )]
2ρgc Sw2
(1.56)
The pressure drop in the inlet or outlet baffle space is then given by:
∆Pe = ξe ṁ2e + 0.5ξwe ṁ2w
j = A, B, CF, E
∆Pj = ξj ṁ2j
1.6.3
Total shell-side pressure drop
∆Po = ψ [(nb − 1) ∆Py + ∆Pin + ∆Pout ] + ∆Pn
ψ = 3.646Re−0.1934
B
= 1.0
Do ṁB
ReB =
µSm
∆Py = ξy ṁ2w
ReB < 1000
ReB ≥ 1000
where,
nb
= number of baffles.
∆Pin , ∆Pout = the pressure drops in the inlet and outlet baffle spaces.
∆Pn
= the pressure drops in the nozzles.
1.7
(1.57)
(1.58)
Fouling factor
19
(1.59)
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Fluid
River water
Sea water
Cooling water (towers)
Towns water (soft)
Towns water (hard)
Steam condensate
Steam (oil free)
Steam (oil traces)
Refrigerated brine
Air and industrial gases
Flue gases
Organic vapors
Organic liquids
Light hydrocarbons
Heavy hydrocarbons
Boiling organics
Condensing organics
Heat transfer fluids
Aqueous salt solutions
Heat Exchanger Data Book
Coefficient (W.m-2.°C-1)
3000-12,000
1000-3000
3000-6000
3000-5000
1000-2000
1500-5000
4000- 10,000
2000-5000
3000-5000
5000-10,000
2000-5000
5000
5000
5000
2000
2500
5000
5000
3000-5000
Resistance (m2.°C.W-1)
0.0003-0.0001
0.001-0.0003
0.0003-0.00017
0.0003-0.0002
0.001-0.0005
0.00067-0.0002
0.0025-0.0001
0.0005-0.0002
0.0003-0.0002
0.0002-0.000-1
0.0005-0.0002
0.0002
0.0002
0.0002
0.0005
0.0004
0.0002
0.0002
0.0003-0.0002
Figure 1.3: Typical values of fouling coefficients and resistances
1.8
Tube data
Standard tube data:
Tube Size
Outside diameter
inch
inch
mm
BWG
inch
mm
1
4
0.250
6.350
8
0.165
4.191
3
8
0.375
9.525
9
0.148
3.759
1
2
0.500
12.700
10
0.134
3.404
5
8
0.625
15.875
12
0.109
2.769
3
4
0.750
19.050
14
0.083
2.108
7
8
0.875
22.225
16
0.065
1.651
1
1.000
25.400
18
0.049
1.245
1 41
1.250
31.750
20
0.035
0.889
1 21
1.500
38.100
22
0.028
0.711
2
2.000
50.800
24
0.022
0.559
20
Wall thickness
Chapter 2
Plate Heat Exchanger
2.1
Plate
Figure 2.1: Plate
2.2
Heat transfer coefficient
hp de
= 0.26Re0.65 P r0.4
k
ρup de
Re =
µ
(ṁ/nc )
up =
ρAf
21
µ
µw
0.14
(2.1)
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Af = flow area through plates = b × Lw ,
Lw = effective plate width,
de = equivalent diameter = 2b,
b = plate gap = p − t,
p = pitch,
t = plate thickness.
nc = number of channels
Table 2.1: Heat transfer coefficient
Fluid
Coefficient (W/m2 -◦ C)
River water
3000 – 12,000
Sea water
1000 – 3000
Cooling water (towers)
3000 – 6000
Towns water (soft)
3000 – 5000
Towns water (hard)
1000 – 2000
Steam condensate
1500 – 5000
Steam (oil free)
4000 – 10,000
Steam (oil traces)
2000 – 5000
Refrigerated brine
3000 – 5000
Air and industrial gases
5000 – 10,000
Flue gases
2000 – 5000
Organic vapours
5000
Organic liquids
5000
Light hydrocarbons
5000
Heavy hydrocarbons
2000
Boiling organic
2500
Condensaing organics
5000
Heat transfer fluids
5000
Aqueous salt solutions
3000 – 5000
Table 2.2: Fouling factor in PHE
Fluid
Process water
Town water (soft)
Town water (hard)
Cooling water (treated)
Sea water
Lubricating oil
Light organics
Process fluids
Fouling factor (m2 -◦ C/W)
0.00003
0.00007
0.00017
0.00012
0.00017
0.00017
0.00010
0.0002 – 0.00005
22
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CHC603
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Number of Transfer Units (NTU)
to − ti
∆Tlm
(2.2)
∆Tm = Ft ∆Tlm
(2.3)
NT U =
Corrected mean temperature difference,
2.2.2
Correction factor, Ft
Refer figure – 2.2
Figure 2.2: Log mean temperature correction factor for plate heat exchangers
2.3
2.3.1
Pressure drop
Pressure drop in flow through plates
∆Pp = 8jf
Lp = effective plate length, = Lv − dpt
jf = 0.6Re−0.3 for turbulent flow.
23
Lp
de
ρu2p
2
(2.4)
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Pressure drop in flow through port
ρu2pt
NP
∆Ppt = 1.3
2
(2.5)
NP = number of passes,
πd2pt
ṁ
upt = velocity in port =
, where Ap =
ρAp
4
Plate sizes
B
L2
D
PP
E
C
A
2.4
24
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Plate
No.
PL01
PL02
PL03
PL04
PL05
PL06
PL07
PL08
PL09
PL10
PL11
PL12
PL13
PL14
PL15
PL16
PL17
PL18
PL19
PL20
PL21
PL22
PL23
PL24
PL25
PL26
PL27
PL28
PL30
PL31
PL32
PL33
PL34
PL33
Max
Pressure
bar
16
16
16
16
25
25
25
25
25
16
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
CHC603
Heat Exchanger Data Book
Table 2.3: Plate dimensions
C
D
E
L2
A
B
mm
460
800
837
1066
470
765
733
933
1182
1080
1160
1332
1579
1826
2320
1470
1835
2200
1470
1835
2200
2687
1380
1740
2100
2460
1930
2320
2710
3100
2500
2855
3211
3567
mm
160
160
310
310
185
185
310
310
310
440
480
480
480
480
480
620
620
620
620
620
620
620
760
760
760
760
980
980
980
980
1370
1370
1370
1370
mm
336
675
590
819
381
676
494
694
894
650
719
894
1141
1388
1882
941
1306
1671
941
1306
1671
2157
770
1130
1490
1850
1100
1490
1879
2267
1466
1822
2178
2534
mm
65
65
135
135
70
70
126
126
126
202
225
225
225
225
225
290
290
290
290
290
290
290
395
395
395
395
480
480
480
480
672
672
672
672
25
mm
85
85
132
132
45
45
128
128
128
200
204
204
204
204
204
225
225
225
225
225
225
225
285
285
285
285
365
365
365
365
480
480
480
480
mm
150 – 600
150 – 600
250 – 1000
250 – 1000
250 – 1000
250 – 1000
250 – 1000
250 – 1000
250 – 1000
500 – 2500
500 – 2500
500 – 3000
500 – 3000
500 – 3000
500 – 3000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
500 – 4000
1780 – 5280
1780 – 5280
1780 – 5280
1780 – 5280
1980 – 5980
1980 – 5980
1980 – 5980
1980 – 5980
PP
mm
pcs. × 2.4
pcs. × 2.4
pcs. × 2.4
pcs. × 2.4
pcs. × 2.7
pcs. × 2.7
pcs. × 2.9
pcs. × 2.9
pcs. × 2.9
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.5
pcs. × 3.5
pcs. × 3.5
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.1
pcs. × 3.8
pcs. × 3.8
pcs. × 3.8
pcs. × 3.8
pcs. × 4.1
pcs. × 4.1
pcs. × 4.1
pcs. × 4.1
Port
size
1”
1”
2”
2”
1”
1”
2”
2”
2”
DN80
DN100
DN100
DN100
DN100
DN100
DN150
DN150
DN150
DN150
DN150
DN150
DN150
DN200
DN200
DN200
DN200
DN300
DN300
DN300
DN300
DN500
DN500
DN500
DN500
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Table 2.4: Pipe sizes for PHE
NB
DN
Outside
Diameter
OD
(inches)
mm
(inches)
(inches)
(inches)
1/8
1/4
3/8
1/2
3/4
1
1 1/4
1 1/2
2
2 1/2
3
4
6
8
10
12
14
16
18
20
6
8
10
15
20
25
32
40
50
65
80
100
150
200
250
300
350
400
450
500
0.405
0.54
0.675
0.84
1.05
1.315
1.66
1.9
2.375
2.875
3.5
4.5
6.625
8.625
10.75
12.75
14
16
18
20
0.0680
0.0880
0.0910
0.1090
0.1130
0.1330
0.1400
0.1450
0.1540
0.2030
0.2160
0.2370
0.2800
0.3220
0.3650
0.4060
0.4380
0.5000
0.5620
0.5940
0.2690
0.3640
0.4930
0.6220
0.8240
1.0490
1.3800
1.6100
2.0670
2.4690
3.0680
4.0260
6.0650
7.9810
10.0200
11.9380
13.1240
15.0000
16.8760
18.8120
Pipe Size
26
Wall
Inside
Thickness Diameter
-tID
Chapter 3
Condenser Design
3.1
HTC in Vertical condenser
Heat transfer coefficient for condensation on vertical tubes is given by Nusselt theory,
k 3 ρL (ρL − ρv ) g
h = 1.47 L
µ2L Re
1/3
for Re ≤ 30
(3.1)
for 30 ≤ Re ≤ 1600
(3.2)
for Re ≥ 1600 and P r ≤ 10
(3.3)
1/3
Re [kL3 ρL (ρL − ρv ) g/µ2L ]
1.08Re1.22 − 5.2
1/3
Re [kL3 ρL (ρL − ρv ) g/µ2L ]
h=
8750 + 58P rL−0.5 (Re0.75 − 253)
h=
Re =
where
Γ=
3.2
4Γ
µL
ṁ
nt πD
HTC in Horizontal Condenser
Heat transfer coefficient for condensation on horizontal single tube or a single row of tubes is
given by Nusselt theory,
kL3 ρL (ρL − ρv ) g
h = 1.52
µ2L Re
1/3
for Re ≤ 3200
Re =
where
Γ=
kL
ρL
ρv
4Γ
µL
ṁ
nt L
= thermal conductivity of condensate at average film temperature
= density of condensate at average film temperature
= density of vapour
27
(3.4)
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µL
ṁ
nt
L
=
=
=
=
CHC603
Heat Exchanger Data Book
viscosity of condensate at average film temperature
rate of condensation at average film temperature
number of tubes in tube bank
tube length
for Nr tube rows stacked vertically,
hNr =
h
(3.5)
1/6
Nr
for circular tube bundles used in shell-and-tube condensers,
3
1/3
kL ρL (ρL − ρv ) g
h = 1.52
4µL Γ∗
(3.6)
where,
Γ∗ =
ṁ
2/3
nt L
Average film temperature,
Tf = 0.75Tw + 0.25Tsat
3.3
(3.7)
Condensation with subcooling
Sadisivan and Lienhard equation,
1/4
h
0.228
= 1 + 0.683 −
ε
hN u
P rL
for P rL ≥ 0.6
(3.8)
where,
CpL µL
kL
CpL (Tsat − Tw )
ε=
λ
P rL =
where
hN u
Tsat
Tw
λ
=
=
=
=
3.4
is the heat-transfer coefficient given by the basic Nusselt theory.
condensation temperature
tube wall temperature
latent heat of condensation.
Condensation with desuperheating
1/4
h
Cpv (Tv − Tsat )
= 1+
hN u
λ
where
hN u
Cpv
Tsat
Tv
λ
=
=
=
=
=
is the heat-transfer coefficient given by the basic Nusselt theory.
specific heat of vapour
condensation temperature
vapour temperature
latent heat of condensation.
28
(3.9)
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CHC603
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Condensation in vertical tubes with vapour downflow
The correlation of Boyko and Kruzhilin,
h = hLo [1 + x (ρL − ρv ) /ρv ]0.5
(3.10)
where
x
= vapour weight fraction
hLo = heat-transfer coefficient for total flow as liquid
3.6
Condensation outside horizontal tubes
McNaught developed the following simple correlation for shear-controlled condensation in
tube bundles:
h
(3.11)
= 1.26Xtt−0.78
hL
where,
Xtt
hL
= Lockhart-Martinelli parameter, (refer section – 4.3)
= heat-transfer coefficient for the liquid phase flowing alone through the bundle.
(refer chapter – 1)
************
29
This page intentionally kept blank.
Chapter 4
Reboiler Design
4.1
Nucleate Boiling
4.1.1
The Forster-Zuber correlation
hnb
0.25
0.75
kL0.79 CpL0.45 ρ0.49
∆Te0.24 ∆Psat
L gc
= 0.00122
σ 0.5 µL0.29 λ0.24 ρ0.24
v
(4.1)
where,
hnb
kL
CpL
ρL
µL
σ
ρv
λ
gc
∆Te
Tw
Tsat
∆Psat
Psat (T )
=
=
=
=
=
=
=
=
=
=
=
=
=
=
nucleate boiling heat-transfer coefficient, Btu/h·ft2 ·◦ F(W/m2 ·K)
liquid thermal conductivity, Btu/h·ft·◦ F (W/m·K)
liquid heat capacity, Btu/lbm ·◦ F(J/kg· K)
liquid density, lbm/ft3 (kg/m3 )
liquid viscosity, lbm/ft·h (kg/m·s)
surface tension, lbf/ft(N/m)
liquid density, lbm/ft3 (kg/m3 )
latent heat of vaporization, Btu/lbm (J/kg)
unit conversion factor = 4.17 × 108 lbm·ft/lbf·h2 (1.0 kg·m/N·s2 )
Tw − Tsat , ◦ F(K)
tube-wall temperature, ◦ F(K)
saturation temperature at system pressure, ◦ F(K)
Psat (Tw ) − Psat (Tsat ), lbf/ft2 (Pa)
vapor pressure of fluid at temperature T, lbf/ft2 (Pa)
Any consistent set of units can be used with Equation - 4.1, including the English and SI
units shown above.
4.1.2
The Mostinski correlation
In English unit,
hnb = 0.00622Pc0.69 q̂ 0.7 F p
where,
hnb
Pc
q̂
Fp
=
=
=
=
nucleate boiling heat-transfer coefficient, Btu/h·ft2 ·◦ F
fluid critical pressure, psia
heat flux, Btu/h·ft2 = hnb ∆Te
pressure correction factor, dimensionless
31
(4.2)
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In SI units,
hnb = 0.00417Pc0.69 q̂ 0.7 F p
(4.3)
where,
hnb
Pc
q̂
= nucleate boiling heat-transfer coefficient, W/m2 ·K
= fluid critical pressure, kPa
= heat flux, W/m2 = hnb ∆Te
The pressure correction factor given by:
h
−1 i 2
F p = 2.1Pr0.27 + 9 + 1 − Pr2
Pr
(4.4)
where, Pr = P/Pc = reduced pressure.
4.1.3
The Cooper correlation
In English unit same as that of equation – 4.2,
hnb = 21q̂ 0.67 Pr0.12 (− log10 Pr )−0.55 M −0.5
(4.5)
In SI unit same as that of equation – 4.3,
hnb = 55q̂ 0.67 Pr0.12 (− log10 Pr )−0.55 M −0.5
(4.6)
where M is the molecular weight of the fluid.
4.1.4
The Stephan-Abdelsalam correlation
q̂dB
kL Tsat
α 2 ρL
Z2 = L
gc σdB
gc λd2B
Z3 =
αL2
ρv
Z4 =
ρL
ρL − ρv
Z5 =
ρL
0.5
2gc σ
dB = 0.0146θc
g (ρL − ρv )
Z1 =
where,
dB
θc
g
gc
=
=
=
=
theoretical diameter of bubbles leaving surface, ft(m)
contact angle in degrees
gravitational acceleration, ft/h2 (m/s2 )
4.17 × 108 lbm·ft/lbf·h2 (1.0 kg·m/N·s2 )
32
(4.7)
(4.8)
(4.9)
(4.10)
(4.11)
(4.12)
University of Mumbai
αL
q̂
kL
Tsat
σ
ρL , ρv
λ
1 Btu
=
∝
∝
∝
∝
∝
∝
=
CHC603
Heat Exchanger Data Book
liquid thermal diffusivity, ft2 /s (m2 /s)
Btu/h·ft2 (W/m2 )
Btu/h·ft·◦ F (W/m·K)
◦
R (K)
lbf/ft (N/m)
lbm/ft3 (kg/m3 )
ft·lbf/lbm (J/kg)
778 ft·lbf
The heat-transfer coefficient is given by the following equation:
hnb dB
= 0.23Z10.674 Z20.35 Z30.371 Z40.297 Z5−1.73
kL
Fluid group
Water
Hydrocarbons (including alcohols)
Refrigerants (including CO2 , propane, n-butane)
Cryogenic fluids (including methane, ethane)
4.1.5
Contact angle (θc ) in
45
35
35
1
(4.13)
◦
Boiling mixtures
The coefficient, hideal , is an average of the pure component values that is calculated as follows:
#
" n
X xi
(4.14)
hideal =
h
nb,i
i=1
where hnb,i is the heat-transfer coefficient for pure component i. So heat transfer coefficient
for mixture is,
hnb
−1
BR · hideal
−q̂
= hideal 1 +
1 − exp
q̂
ρL λβ
(4.15)
where
BR
TD
TB
β
=
=
=
=
4.1.6
TD − TB = boiling range
dew-point temperature
bubble-point temperature
0.0003 m/s (SI units) = 3.54 ft/h (English units)
Convective effects in tube bundles
The average boiling heat-transfer coefficient, hb , is expressed as follows:
hb = hnb Fb + hnc
(4.16)
where hnc is a heat-transfer coefficient for liquid-phase natural convection and Fb is a factor
that accounts for the effect of the thermosyphon-type circulation in the tube bundle. The
33
University of Mumbai
CHC603
Heat Exchanger Data Book
bundle convection factor is correlated in terms of bundle geometry by the following empirical
equation,
0.75
0.785Db
− 1.0
(4.17)
Fb = 1.0 + 0.1
C1 (PT /Do )2 Do
where,
Db
Do
PT
C1
=
=
=
=
=
bundle diameter (outer tube-limit diameter)
tube OD
tube pitch
1.0 for square and rotated square layouts
0.866 for triangular layouts
For larger temperature differences, therefore, Palen suggests using a rough approximation
for hnc of 250 W/m2 · K (44 Btu/h· ft2 ·◦ F) for hydrocarbons and 1000 W/m2 · K (176 Btu/h·
ft2 ·◦ F) for water and aqueous solutions.
4.2
Critical heat flux
The equation for critical heat flux is generally used in the following form:
√
q̂c = 0.149λ ρv [σggc (ρL − ρv )]0.25
4.2.1
(4.18)
Mostinski correlation
Boiling on single tube. For English unit,
q̂c = 803Pc Pr0.35 (1 − Pr )0.9
(4.19)
where q̂c Btu/h·ft2 and Pc in psia.
For SI unit,
q̂c = 367Pc Pr0.35 (1 − Pr )0.9
(4.20)
where q̂c W/m2 and Pc in kPa.
For tube bundles, Palen presented the following correlation:
q̂c,bundle = q̂c,tube φb
(4.21)
where
q̂c,bundle = critical heat flux for tube bundle
q̂c,tube = critical heat flux for a single tube
φb
= bundle correction factor
= 3.1ψb
for ψb < 1.0/3.1 ∼
= 0.323
= 1.0 otherwise
ψb
= dimensionless bundle geometry parameter =
Db
A
Do
L
nt
=
=
=
=
=
πDb L
A
bundle diameter
bundle surface area = nt πDo L for plain tubes
tube OD
tube length
number of tubes in bundle
34
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4.3
4.3.1
CHC603
Heat Exchanger Data Book
Two Phase Flow
Pressure drop correlations
The Lockhart-Martinelli correlation
The two-phase pressure gradient is expressed as,
(∆Pf /L)tp = φ2L (∆Pf /L)L
(4.22)
where
φ2L
(∆Pf /L)L
(∆Pf /L)tp
= two-phase multiplier
= negative pressure gradient for liquid alone
= negative two-phase pressure gradient
The two-phase multiplier is a function of the parameter, X, which is defined as follows:
(∆Pf /L)L 0.5
(4.23)
X=
(∆Pf /L)v
where (∆Pf /L)v is the pressure gradient that would occur if the vapor phase flowed alone in
the conduit.The relationship between φ2L and X was given in graphical form by Lockhart and
Martinelli, and subsequently expressed analytically by Chisholm as follows:
φ2L = 1 +
1
C
+ 2
X X
(4.24)
The constant, C, depends on whether the flow in each phase is laminar or turbulent, as shown
in Table – 4.1.
Table 4.1: Values of the Constant in Equation – 4.24
Liquid
Vapour
Notation
ReL
ReV
C
Turbulent
Turbulent
tt
> 2000 > 2000 20
Viscous (laminar) Turbulent
vt
< 1000 > 2000 12
Turbulent
Viscous (laminar)
tv
> 2000 < 1000 10
Viscous (laminar) Viscous (laminar)
vv
< 1000 < 1000 5
For the turbulent-turbulent case,
0.9 0.5 0.1
ρv
µL
1−x
Xtt =
x
ρL
µv
(4.25)
where, x is vapour mass fraction.
The Chisholm correlation
The two-phase pressure gradient is expressed as,
(∆Pf /L)tp = φ2LO (∆Pf /L)LO
where,
35
(4.26)
University of Mumbai
φ2LO
(∆Pf /L)LO
(∆Pf /L)tp
CHC603
Heat Exchanger Data Book
= two-phase multiplier
= negative pressure gradient for liquid alone
= negative two-phase pressure gradient
The correlation for the two-phase multiplier is the following:
o
n
(2−n)/2
2
2−n
2
+x
φLO = 1 + Y − 1 B [x (1 − x)]
Y =
ρL
ρv
0.5 µv
µL
(4.27)
n/2
where n = 0.2314
For English unit with G in units of lbm/h · f t2 :
√
B = 1500/ G
√ = 14250/ Y G
√ = 399000/ Y 2 G
(4.28)
(0 < Y ≤ 9.5)
(9.5 < Y ≤ 28)
(4.29)
(Y > 28)
For calculations in SI units, the following conversion can be used:
G(lbm/h · f t2 ) ≡ 737.35G(kg/s · m2 )
The Friedel correlation
The two-phase pressure gradient is expressed in the same manner as the Chisholm method,
Equation – 4.26 with the following correlation for the two-phase multiplier:
φ2LO = E +
3.24F H
Fr
We0.035
0.045
(4.30)
where,
E = (1 − x)2 + x2 (µv /µL )0.2314 (ρL /ρv )
F = x0.78 (1 − x)0.24
H = (ρL /ρv )0.91 (µv /µL )0.19 (1 − µv /µL )0.7
G2
Fr =
= Froude numbar
gDi ρ2tp
G2 Di
We =
= Weber number
gc ρtp σ
Di = internal diameter of conduit
ρtp = two-phase density
For the purpose of this correlation, the two-phase density is calculated as follows:
ρtp = [x/ρv + (1 − x) /ρL ]−1
where, x is vapour mass fraction.
36
(4.31)
University of Mumbai
CHC603
Heat Exchanger Data Book
Slip ratio,
r
SR =
ρL
ρtp
(4.32)
void fraction is computed
εv =
x
x + SR (1 − x) ρv /ρL
(4.33)
Finally, the average two-phase density is computed as,
ρ̄tp = εv ρv + (1 − εv ) ρL
(4.34)
The Müller-Steinhagen and Heck(MSH) correlation
The correlation is reformulated in the Chisholm format of Equation – 4.26 with the two-phase
multiplier given by the following equation:
φ2LO = Y 2 x3 + 1 + 2x Y 2 − 1 (1 − x)1/3
(4.35)
where x is the vapor mass fraction and Y is the Chisholm parameter (equation – 4.28).
4.4
Convective Boiling in Tubes
4.4.1
Heat transfer coefficient
The Chen correlation
hb = SCH hnb + Fx hL
(4.36)
where
hb
hnb
SCH
Fx
Re
= convective boiling heat-transfer coefficient
= nucleate boiling heat-transfer coefficient
−1
= (1 + 2.53 × 10−6 Re1.17 )
0.736
= 2.35 Xtt−1 + 0.213
for (Xtt < 10)
= 1.0 for (Xtt ≥ 10)
= ReL (Fx )1.25
The heat flux is calculated as follows:
q̂ = SCH hnb (Tw − Tsat ) + hL (Tw − Tb )
(4.37)
whereas convective heat transfer coefficient, hL , can be calculated using Dittus-Boelter equation,
0.4
hL = 0.023 (kL /Di ) Re0.8
(4.38)
L P rL
37
University of Mumbai
4.4.2
CHC603
Heat Exchanger Data Book
Critical heat flux
The following simple correlation for vertical thermosyphon reboilers was given by Palen
0.35 0.61 0.25
q̂c = 16070 D2 /L
Pc P r (1 − P r)
English Unit
(4.39)
0.35
q̂c = 23660 D2 /L
Pc0.61 P r0.25 (1 − P r)
SI units
(4.40)
where
q̂c
D
L
Pr
Pc
=
=
=
=
=
critical heat flux, Btu/h · f t2 (W/m2 )
tube ID, ft (m)
tube length, ft(m)
reduced pressure in tube
critical pressure of fluid, psia (kPa)
For flow in horizontal tubes, the dimensionless correlation of Merilo is recommended by
Hewitt et al.
−0.511 1.27
L
ρL − ρv
q̂c
−0.34
= 575γH
(1 + ∆Hin /λ)1.64
(4.41)
Gλ
D
ρv
where
γH =
GD
µL
µ2L
gc σDρL
−1.58 (ρL − ρv ) gD2
gc σ
−1.05 µL
µv
6.41
(4.42)
The correlation cover the ranges 5.3 ≤ D ≤ 19.1 mm, 700 ≤ G ≤ 8100 kg/s·m2 , 13 ≤ ρL /ρv ≤
21.
4.5
4.5.1
Film Boiling
Heat transfer coefficient
A combined heat-transfer coefficient, ht , for both convection and radiation can be calculated
from the following equation:
4/3
4/3
1/3
ht = hf b + hr ht
(4.43)
For saturated film boiling on the outside of a single horizontal tube,
0.25
gρv (ρL − ρv ) Do3 (λ + 0.76Cp,v ∆Te )
hf b Do
= 0.62
kv
kv µv ∆Te
(4.44)
Here, Do is the tube OD. hr is the radiative heat-transfer coefficient calculated from the
following equation:
4
εσSB (Tw4 − Tsat
)
hr =
(4.45)
Tw − Tsat
where,
ε
= emissivity of tube wall
σSB = Stefan-Boltzmann constant
= 5.67 × 10−8 W/m2 · K 4 = 1.714 × 10−9 Btu/h · f t2 ·◦ R4
If hr < hf b , Equation – 4.43 can be approximated by the following explicit formula for ht :
ht = hf b + 0.75hr
38
(4.46)
University of Mumbai
CHC603
4.6
Design equations
4.6.1
Number of nozzles
Heat Exchanger Data Book
For a tube bundle of length L and diameter Db , the number, Nn , of nozzle pairs (feed and
return) is determined from the following empirical equation,
L
5Db
Nn =
4.6.2
(4.47)
Shell diameter
Vapour loading,
VL = 2290ρv
σ
ρL − ρv
0.5
(4.48)
where
VL
ρv , ρL
σ
= vapor loading (lbm/h · f t3 )
= vapor and liquid densities (lbm/f t3 )
= surface tension (dyne/cm)
The dome segment area, SA, is calculated from the vapour loading as follows:
SA =
ṁV
L × VL
(4.49)
The segment area till semicircle is given by,
Ds2
(θ − sin θ)
8
2h
−1
θ = 2 cos
1−
Ds
SA =
(4.50)
(4.51)
where, Ds Shell ID and h is height of the segment. When segment exceeds semicircle the
segment area is area of circle minus area of segment whose height in the circle diameter minus
height of the given segment.
4.7
4.7.1
Frictional losses in pipe
Friction factor
Reynold’s number
NRe =
dvρ
µ
Friction factor in Laminar flow:
f=
16
NRe
39
University of Mumbai
CHC603
Heat Exchanger Data Book
Friction factor in turbulent flow:
A. For smooth pipe/tubes (Turbulent)
i) f = 0.046NRe −0.2
0.125
ii) f = 0.0014 +
NRe 0.32
iii) von-Karman equation
for 50000 < NRe < 1 × 106
for 3000 < NRe < 3 × 106
p
1
p
= 2.5 ln NRe f /8 + 1.75
f /2
B. For Commercial pipes (Turbulent)
i) Colebrook equation
1
√ = 2 log
4f
D
2κ
+ 1.74
ii) Generalised equation
−0.2314
f = 0.3673NRe
4.7.2
Pressure drop in pipe
2
L ρv
∆P = 4f
d
2
4.7.3
Maximum gas/vapour velocity in tubes
For plain carbon steel tube in English unit,
1800
vmax = √
PM
(4.52)
1440
vmax = √
PM
(4.53)
in SI units,
where,
vmax = maximum velocity, ft/s (m/s)
P
= gas pressure, psia(kPa)
M = molecular weight of gas
Multiply equation – (4.52) or (4.53) with 1.5 for stainless steel and 0.6 for copper tube.
4.7.4
Maximum velocity of liquids in tubes
i. Maximum recommended velocity of water in plain carbon steel tube is 10 ft/s (3 m/s).
ii. Multiply above value with 1.5 for stainless steel and 0.6 for copper tube.
p
iii. Multiply above value with the factor (ρwater /ρliquid ) if liquid is other than water.
40
University of Mumbai
4.7.5
CHC603
Heat Exchanger Data Book
Maximum velocity of two-phase flow in tubes/pipe
English unit,
s
vmax =
4000
ρtp
(4.54)
5924
ρtp
(4.55)
SI unit,
s
vmax =
vmax = maximum velocity, ft/s (m/s)
ρtp = density of two-phase mixture, lbm/ft3 (kg/m3 )
4.8
Design of Vertical Thermosyphon Reboiler
Figure 4.1: Configuration of vertical thermosyphon reboiler system.
4.8.1
Pressure balance
PB − PA = ρL (g/gc ) (zA − zB ) − 4f
Lin
Din
G2in
2ρL
(4.56)
The subscript in refers to the inlet line to the reboiler.
PC − PB = ρL (g/gc ) LBC − 4f
41
LBC
Dt
G2t
2ρL
(4.57)
University of Mumbai
CHC603
Heat Exchanger Data Book
The subscript t in this equation refers to the reboiler tubes.
PD − PC = −∆Pstatic,CD − ∆Pf,CD − ∆Pacc,CD
(4.58)
∆Pstatic,CD = ρ̄tp (g/gc ) LCD
LCD G2t φ̄2LO
∆Pf,CD = 4f
Dt
2ρL
2
Gγ
∆Pacc,CD = t
ρL
(4.59)
(4.60)
(4.61)
Fair recommends calculating ρ̄tp at a vapour weight fraction equal to one-thirds the value at
the reboiler exit using equation – (4.34). where,
γ=
ρL x2e
(1 − xe )2
+
−1
1 − εv,e
ρv εv,e
In this equation, xe and εv,e are the vapour mass fraction and the void fraction at the reboiler
exit.
Fair recommends calculating φ̄2LO at a vapour weight fraction equal to two-thirds the value
at the reboiler exit.
PA − PD =
(G2t − G2ex ) (γ + 1) 4fex Lex G2ex φ2LO,ex
−
ρL
2ρL Dex
(4.62)
In this equation, the subscript ex designates conditions in the exit line from the reboiler.
The relationship between the circulation rate and the exit vapour fraction in the reboiler
in SI units is,
1.234Dt5 ρL (g/gc ) (ρL LAC − ρ̄tp LCD )
"
#

ṁ2i = 
4


Dt
1




2D
(γ
+
1)
−


t
2


Dex
nt
5 5


Dt
Dt
ft


2
2


+
f
L
φ
+
f
L
L
+
L
φ̄
+


in
in
BC
CD
ex
ex
LO,ex
LO
2

Din
nt
Dex 
(4.63)
where,
ṁi
nt
= tube-side mass flow rate (kg/s)
= number of tubes in reboiler
4.8.2
Sensible heating zone
TC − TB
(∆T /L)
=
PC − PB
(∆P/L)
Tsat − TA
= (∆T /∆P )sat
Psat − PA
42
(4.64)
(4.65)
University of Mumbai
CHC603
LBC
∼
=
LBC + LCD
Heat Exchanger Data Book
(∆T /∆P )sat
(∆T /L)
(∆T /∆P )sat −
(∆P/L)
(4.66)
The pressure gradient in the sensible heating zone is calculated as follows:
− (∆P/L) = ρL (g/gc ) + ∆Pf,BC /L
(4.67)
The temperature gradient in the sensible heating zone is estimated as follows:
∆T /L =
nt πDo UD ∆Tm
ṁi CpL
(4.68)
Here, UD and ∆Tm are the overall coefficient and mean driving force, respectively, for the
sensible heating zone.
4.8.3
Mist flow limit
Tube-side mass flux at onset of mist flow,
Gt,mist = 1.8 × 106 Xtt
Gt,mist = 2.44 × 103 Xtt
(lbm/h · f t2 )
(kg/s · m2 )
********************
43
(4.69)
(4.70)
This page intentionally kept blank.
Part II
Data Sheet
45
Heat Exchanger Specification Sheet
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
Company:
Location:
Service of Unit:
Item No.:
Date:
Size
Surf/unit(eff.)
Rev No.:
mm
Fluid allocation
Fluid name
Fluid quantity, Total
Vapor (In/Out)
Liquid
Noncondensable
Temperature (In/Out)
Dew / Bubble point
Density
Viscosity
Molecular wt, Vap
Molecular wt, NC
Specific heat
Thermal conductivity
Latent heat
Pressure
Velocity
Pressure drop, allow./calc.
Fouling resist. (min)
Heat exchanged
Transfer rate, Service
Prepared by:
Job No.:
Type
Connected in
parallel
Shells/unit
Surf/shell (eff.)
m2
PERFORMANCE OF ONE UNIT
Shell Side
series
m2
Tube Side
kg/h
kg/h
kg/h
kg/h
C
C
kg/m3
cp
kJ/(kg*C)
W/(m*K)
kJ/kg
mmH2O(g)
m/s
mmH2O
m2*K/W
kcal/h
Dirty
CONSTRUCTION OF ONE SHELL
Shell Side
kgf/cm2
C
Design/Test pressure
Design temperature
Number passes per shell
Corrosion allowance
mm
Connections
In
Size/rating
Out
mm
Intermediate
Tube No.
OD
Tube type
Shell
ID
Channel or bonnet
Tubesheet-stationary
Floating head cover
Baffle-crossing
Baffle-long
Supports-tube
Bypass seal
Expansion joint
RhoV2-Inlet nozzle
Gaskets - Shell side
Floating head
Code requirements
Weight/Shell
Remarks
Tks-
MTD corrected
Clean
C
W/(m2*K)
Sketch
Tube Side
avg
mm
Length
mm
Pitch
Material
Tube pattern
OD
mm
Shell cover
Channel cover
Tubesheet-floating
Impingement protection
Type
Cut(%d)
Spacing: c/c
Seal type
Inlet
U-bend
Type
Tube-tubesheet joint
groove/expand
Type
Bundle entrance
Bundle exit
Tube Side
Filled with water
TEMA class
Bundle
mm
mm
mm
kg/(m*s2)
kg
Company
PLATE-AND-FRAME HEAT EXCHANGER
DATA SHEET (SI UNITS)
PROCESS
PO No.:
Doc. No.:
Engineering contractor
Page 1 of
Customer:
Project:
Location:
Item No.:
Service:
Vendor:
Order/enq. No.:
Model:
Serial No.:
01 CASE
HOT SIDE
COLD SIDE
02 Fluid
03 Total flow
(kg/s)
04 Flow per exchanger
(kg/s)
05 Design temperature (max.)
06 Minimum design metal temp.
07 Design pressure
08 Pressure drop allow./calc.-
( C)
( C)
[kPa (ga)]
(kPa)
/
/
09 Wall temperature min./max.
( C)
/
/
10 Fouling margin a
(%)
11 OPERATING DATA
12 Liquid flow
13 Vapour flow
14 Non-condensables flow
15 Operating temperature
16 Operating pressure
INLET
OUTLET
INLET
OUTLET
(kg/s)
(kg/s)
(kg/s)
( C)
[kPa (ga)]
17 LIQUID PROPERTIES
18 Density
19 Specific heat capacity
20 Dynamic viscosity
21 Thermal conductivity
22 Surface tension
(kg/m3)
(kJ/kg·K)
(mPa·s)
(W/m·K)
(N/m)
23 VAPOUR PROPERTIES
24 Density
25 Specific heat capacity
26 Dynamic viscosity
27 Thermal conductivity
28 Relative molecular mass
29 Relative molecular mass,
non-condensables
30 Dew point/bubble point
31 Solids maximum size
32 Solids concentration (% volume)
33 Latent heat
34 Critical pressure
35 Critical temperature
36
(kg/m3)
(kJ/kg·K)
(mPa·s)
(W/m·K)
(kg/kmol)
(kg/kmol)
( C)
(mm)
(kJ/kg)
[kPa (abs)]
( C)
37 Total heat exchanged
38 U a
39 LMTD
40 Heat transfer area
41 Stream heat transfer coefficient
(kW)
(W/m2·K)
( C)
(m2)
(W/m2·K)
a Fouling margin = [(U
clean /Uservice) – 1]
100 % where U = Overall heat transfer coefficient (thermal transmittance).
Rev. No.
Revision
Clean condition:
Service:
/
Date
Prepared by
Reviewed by