Post on 21-Feb-2018
Contents
I Formulae, graphs and tables 1
1 Shell and Tube Heat Exchanger 31.1 Log Mean Temperature difference . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1 Correction factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.2 Heat transfer through tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.3 Shell-side heat-transfer coefficient(Kern’s Method) . . . . . . . . . . . . . . . . 61.4 Bell’s method for HTC shell side . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.4.1 HTC cross flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.4.2 Fn, tube row correction factor . . . . . . . . . . . . . . . . . . . . . . . 71.4.3 Fw, window correction factor . . . . . . . . . . . . . . . . . . . . . . . . 71.4.4 Fb, bypass correction factor . . . . . . . . . . . . . . . . . . . . . . . . 81.4.5 FL, Leakage correction factor . . . . . . . . . . . . . . . . . . . . . . . 8
1.5 Pressure Drop in shell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5.1 Cross-flow zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5.2 ∆Pi ideal tube bank pressure drop . . . . . . . . . . . . . . . . . . . . 91.5.3 F ′b , bypass correction factor for pressure drop . . . . . . . . . . . . . . 91.5.4 F ′L, leakage factor for pressure drop . . . . . . . . . . . . . . . . . . . . 111.5.5 Window-zone pressure drop . . . . . . . . . . . . . . . . . . . . . . . . 111.5.6 End zone pressure drop . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.5.7 Total shell-side pressure drop . . . . . . . . . . . . . . . . . . . . . . . 141.5.8 Shell and bundle geometry . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.6 Wills-Johnston Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.6.1 Streams and flow areas . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.6.2 Flow resistances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.6.3 Total shell-side pressure drop . . . . . . . . . . . . . . . . . . . . . . . 19
1.7 Fouling factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.8 Tube data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2 Plate Heat Exchanger 212.1 Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.2 Heat transfer coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.1 Number of Transfer Units (NTU) . . . . . . . . . . . . . . . . . . . . . 232.2.2 Correction factor, Ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3 Pressure drop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232.3.1 Pressure drop in flow through plates . . . . . . . . . . . . . . . . . . . 232.3.2 Pressure drop in flow through port . . . . . . . . . . . . . . . . . . . . 24
2.4 Plate sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
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University of Mumbai CHC603 Heat Exchanger Data Book
3 Condenser Design 273.1 HTC in Vertical condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.2 HTC in Horizontal Condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.3 Condensation with subcooling . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.4 Condensation with desuperheating . . . . . . . . . . . . . . . . . . . . . . . . 283.5 Condensation in vertical tubes with vapour downflow . . . . . . . . . . . . . . 293.6 Condensation outside horizontal tubes . . . . . . . . . . . . . . . . . . . . . . 29
4 Reboiler Design 314.1 Nucleate Boiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1.1 The Forster-Zuber correlation . . . . . . . . . . . . . . . . . . . . . . . 314.1.2 The Mostinski correlation . . . . . . . . . . . . . . . . . . . . . . . . . 314.1.3 The Cooper correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.1.4 The Stephan-Abdelsalam correlation . . . . . . . . . . . . . . . . . . . 324.1.5 Boiling mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334.1.6 Convective effects in tube bundles . . . . . . . . . . . . . . . . . . . . . 33
4.2 Critical heat flux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344.2.1 Mostinski correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.3 Two Phase Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354.3.1 Pressure drop correlations . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.4 Convective Boiling in Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374.4.1 Heat transfer coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . 374.4.2 Critical heat flux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.5 Film Boiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384.5.1 Heat transfer coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.6 Design equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.6.1 Number of nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.6.2 Shell diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.7 Frictional losses in pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.7.1 Friction factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.7.2 Pressure drop in pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404.7.3 Maximum gas/vapour velocity in tubes . . . . . . . . . . . . . . . . . . 404.7.4 Maximum velocity of liquids in tubes . . . . . . . . . . . . . . . . . . . 404.7.5 Maximum velocity of two-phase flow in tubes/pipe . . . . . . . . . . . 41
4.8 Design of Vertical Thermosyphon Reboiler . . . . . . . . . . . . . . . . . . . . 414.8.1 Pressure balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414.8.2 Sensible heating zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424.8.3 Mist flow limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
II Data Sheet 45
iv
Chapter 1
Shell and Tube Heat Exchanger
1.1 Log Mean Temperature difference
For counter current flow,
∆Tlm =(Thin − Tcout)− (Thout − Tcin)
ln
(Thin − TcoutThout − Tcin
) (1.1)
∆Tm = Ft∆Tlm (1.2)
1.1.1 Correction factor
For one shell pass and two or more even tube passes shell and tube heat exchanger,
Ft =
√(R2 + 1)ln
[1− S
1−RS
]
(R− 1) ln
2− S(R + 1−
√(R2 + 1)
)2− S
(R + 1 +
√(R2 + 1)
)
(1.3)
where,
R =Tin − Touttout − tin
(1.4)
S =tout − tinTin − tin
(1.5)
T = Shell side temperaturet = Tube side temperatureTh = hot fluid temperatureTc = cold fluid temperature
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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
Nu = 0.023Re0.8Pr1/3(µ/µw)0.14 (1.6)
for 2100 < Re ≥ 104
Nu = 0.116[Re2/3 − 125
]Pr1/3(µ/µw)0.14
[1− (D/L)2/3
](1.7)
for Re ≤ 2100
Nu = 1.86 [RePr (D/L)]1/3 (µ/µw)0.14 (1.8)
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 =hodek
Pr−1/3(µ/µw)−0.14 (1.10)
lB = baffle spacingDs = shell IDde = equivalent diameter
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University of Mumbai CHC603 Heat Exchanger Data Book
Re =Gsdeµ
(1.11)
Gs =ms
As(1.12)
As =(pt − do)DslB
pt(1.13)
for a square pitch arrangement:
de =1.27
do
(p2t − 0.785d2o
)(1.14)
for an equilateral triangular pitch arrangement:
de =1.10
do
(p2t − 0.917d2o
)(1.15)
1.4 Bell’s method for HTC shell side
hs = hocFnFwFbFL (1.16)
hoc = heat transfer coefficient calculated for cross-flow over an ideal tube bank,no leakage or bypassing.
Fn = correction factor to allow for the effect of the number of vertical tube rows,Fw = window effect correction factor,Fb = bypass stream correction factor,FL = leakage correction factor.
1.4.1 HTC cross flow
See section – (1.3)
hocdokf
= jHPr1/3
(µ
µw
)0.14
(1.17)
1.4.2 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 ∝ (N ′c)−0.18
where N ′c 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 oftubes in the window zones to the total number in the bundle. For Rw refer section – 1.5.8
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University of Mumbai CHC603 Heat Exchanger Data Book
1.4.4 Fb, bypass correction factor
Fb = exp
[−αAb
As
(1−
(2Ns
Ncv
)1/3)]
(1.18)
where,
α = 1.5 for laminar flow, Re < 100,α = 1.35 for transitional and turbulent flow Re > 100,Ab = clearance area between the bundle and the shell, refer equation – (1.35),As = maximum area for cross-flow,Ns = number of sealing strips encountered by the bypass stream in the cross-flow zone,Ncv = the number of constrictions, tube rows, encountered in the cross-flow section.
1.4.5 FL, Leakage correction factor
FL = 1− βL[Atb + 2Asb
AL
](1.19)
where,
βL = a factor obtained from Figure 12.35,Atb = the tube to baffle clearance area, per baffle,Asb = shell-to-baffle clearance area, per baffle,AL = total leakage area = (Atb + Asb).
1.5 Pressure Drop in shell
1.5.1 Cross-flow zones
∆Pc = ∆PiF′bF′L (1.20)
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University of Mumbai CHC603 Heat Exchanger Data Book
1.5.2 ∆Pi ideal tube bank pressure drop
∆Pi = 8jtNcvρu2s2
(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 = (ρusdo/µ).
1.5.3 F ′b , bypass correction factor for pressure drop
The correction factor is calculated from the equation used to calculate the bypass correctionfactor 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.
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University of Mumbai CHC603 Heat Exchanger Data Book
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10
University of Mumbai CHC603 Heat Exchanger Data Book
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1.5.4 F ′L, 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 = F ′L (2 + 0.6Nwv)ρu2z2
(1.22)
where
uz = the geometric mean velocity, =√uwus
uw = the velocity in the window zone, based on the window area less the area occupiedby the tubes, uw = Ws
Awρ
Ws = shell-side fluid mass flow, kg/s,Nwv = 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
Ncv
]F ′b (1.23)
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University of Mumbai CHC603 Heat Exchanger Data Book
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12
University of Mumbai CHC603 Heat Exchanger Data Book
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13
University of Mumbai CHC603 Heat Exchanger Data Book
1.5.7 Total shell-side pressure drop
∆Ps = 2∆Pe + ∆Pc (Nb − 1) +Nb∆Pw (1.24)
where, Nb = LlB− 1
L = Total tube length,lB = baffle spacing
1.5.8 Shell and bundle geometry
Bundle diameter
Db = do
(Nt
K1
)1/n1
(1.25)
where
Nt = number of tubes,Db = bundle diameter, mm,do = tube outside diameter, mm.
Table 1.1: Constants for use in equation – 1.25
Triangular pitch, PT = 1.25do
No. of passes 1 2 4 6 8
K1 0.319 0.249 0.175 0.0743 0.0365
n1 2.142 2.207 2.285 2.499 2.675
Square pitch, PT = 1.25do
No. of passes 1 2 4 6 8
K1 0.215 0.156 0.158 0.0402 0.0331
n1 2.207 2.291 2.263 2.617 2.643
Hb =Db
2−Ds (0.5−Bc) (1.26)
Ncv =Db − 2Hb
p′t(1.27)
Nwv =Hb
p′t(1.28)
Hc= baffle cut height = Ds ×Bc, where Bc is the baffle cut as a fraction,Hb= height from the baffle chord to the top of the tube bundle,Bb= bundle cut = Hb/Db,θb = angle subtended by the baffle chord, rads,Db= bundle diameter.Ds= Shell ID.p′t = pt for square pitch,p′t = 0.87pt for equilateral triangular pitch.
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University of Mumbai CHC603 Heat Exchanger Data Book
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The number of tubes in a window zone Nw is given by:
Nw = Nt ×R′a (1.29)
where, R′a is the ratio of the bundle cross-sectional area in the window zone to the total bundlecross-sectional area, R′a 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 (1.30)
Rw =2Nw
Nt
(1.31)
Aw =
(πD2
s
4×Ra
)−(Nw
πd2o4
)(1.32)
Ra is obtained from Figure 12.41, for the appropriate baffle cut Bc
Atb =ctπdo
2(Nt −Nw) (1.33)
where ct is the diametrical tube-to-baffle clearance; the difference between the hole and tubediameter, typically 0.8 mm.
Asb =csDs
2(2π − θb) (1.34)
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) (1.35)
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University of Mumbai CHC603 Heat Exchanger Data Book
1.6 Wills-Johnston Method
1.6.1 Streams and flow areas
The bypass flow areaSbp = B (Ds −Dot +Npδp) (1.36)
where,
Ds = Shell IDB = central baffle spacingDot = outer tube limit diameterNp = number of tube pass partitions aligned with the cross-flow directionδp = pass partition clearance
Tube-to-baffle leakage flowSt = ntπDoδtb (1.37)
Shell-to-baffle leakage flowSs = πDsδsb (1.38)
where
nt = number of tubes in bundleδtb = tube-to-baffle clearanceδsb = shell-to-baffle clearance
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University of Mumbai CHC603 Heat Exchanger Data Book
Figure 1.2: Typical baffle clearances.
SBW =BD2
ot (π − θot + sin θot)
4Ds (1− 2Bc)−BNpδp (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
ξB =4aDoDsDv (1− 2Bc) (PT −Do)
−3(mBDo
µSBW
)−b2ρgcS2
BW
(1.41)
mB
mo
=
√ξxξoξyξB
(1.42)
where
a= 0.061, b= 0.088 for square and rotated-square pitcha = 0.450, b = 0.267 for triangular pitch
Dv =Ω1P
2T −D2
o
Do
(1.43)
Ω1 = 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:
ξCF =
0.3164Ds
(1− 2Bc
Ω2PT
)(moDe
µSbp
)−0.025+ 2Nss
2ρgcS2bp
(1.44)
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University of Mumbai CHC603 Heat Exchanger Data Book
mCF
mo
=
√ξxξoξyξCF
(1.45)
where
Nss = number of pairs of sealing stripsΩ2 = 1.0 for square pitch
= 1.414 for rotated-square pitch= 1.732 for triangular pitch
De = equivalent diameter for the bypass flow
De =2Sbp
Ds −Dotl + 2B +Np (B + δp)(1.46)
ξy = ξw + ξx (1.47)
ξx =1(
1√ξB
+ 1√ξCF
)2 (1.48)
The tube-to-baffle leakage flow resistance The flow resistance for the tube-to-baffleleakage stream is given by the following equation,
ξA =0.036Bt/δtb + 2.3 (Bt/δtb)
−0.177
2ρgcS2t
(1.49)
where Bt is the baffle thickness. Flow fraction,
mA
mo
=
√ξoξA
(1.50)
where, mo is total mass flow.
The shell-to-baffle leakage flow resistance The flow resistance for the shell-to-baffleleakage stream is given by an equation,
ξE =0.036Bt/δsb + 2.3 (Bt/δsb)
−0.177
2ρgcS2s
(1.51)
mE
mo
=
√ξoξE
(1.52)
The window flow resistance The window flow resistance is given by
ξw =1.9 exp (0.6856Sw/Sm)
2ρgcS2w
(1.53)
mw
mo
=
√ξoξy
(1.54)
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University of Mumbai CHC603 Heat Exchanger Data Book
Inlet and outlet baffle spaces The cross-flow resistance in the end spaces is estimatedby the following equation
ξe = 0.5ξx
(B
Be
)2 [1 +
Dotl
Ds (1− 2Bc)
](1.55)
the end baffle spaces. The flow resistance in the end windows is calculated as follows
ξwe =1.9 exp [0.6856SwB/(SmBe)]
2ρgcS2w
(1.56)
The pressure drop in the inlet or outlet baffle space is then given by:
∆Pe = ξem2e + 0.5ξwem
2w (1.57)
∆Pj = ξjm2j j = A,B,CF,E (1.58)
1.6.3 Total shell-side pressure drop
∆Po = ψ [(nb − 1) ∆Py + ∆Pin + ∆Pout] + ∆Pn (1.59)
ψ = 3.646Re−0.1934B ReB < 1000
= 1.0 ReB ≥ 1000
ReB =DomB
µSm∆Py = ξym
2w
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 Fouling factor
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University of Mumbai CHC603 Heat Exchanger Data Book
Fluid Coefficient (W.m-2.°C-1) Resistance (m2.°C.W-1)
River water 3000-12,000 0.0003-0.0001 Sea water 1000-3000 0.001-0.0003 Cooling water (towers) 3000-6000 0.0003-0.00017 Towns water (soft) 3000-5000 0.0003-0.0002 Towns water (hard) 1000-2000 0.001-0.0005 Steam condensate 1500-5000 0.00067-0.0002 Steam (oil free) 4000- 10,000 0.0025-0.0001 Steam (oil traces) 2000-5000 0.0005-0.0002 Refrigerated brine 3000-5000 0.0003-0.0002 Air and industrial gases 5000-10,000 0.0002-0.000-1 Flue gases 2000-5000 0.0005-0.0002 Organic vapors 5000 0.0002 Organic liquids 5000 0.0002 Light hydrocarbons 5000 0.0002 Heavy hydrocarbons 2000 0.0005 Boiling organics 2500 0.0004 Condensing organics 5000 0.0002 Heat transfer fluids 5000 0.0002 Aqueous salt solutions 3000-5000 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 Wall thickness
inch inch mm BWG inch mm
14
0.250 6.350 8 0.165 4.191
38
0.375 9.525 9 0.148 3.759
12
0.500 12.700 10 0.134 3.404
58
0.625 15.875 12 0.109 2.769
34
0.750 19.050 14 0.083 2.108
78
0.875 22.225 16 0.065 1.651
1 1.000 25.400 18 0.049 1.245
114
1.250 31.750 20 0.035 0.889
112
1.500 38.100 22 0.028 0.711
2 2.000 50.800 24 0.022 0.559
20
Chapter 2
Plate Heat Exchanger
2.1 Plate
Figure 2.1: Plate
2.2 Heat transfer coefficient
hpde
k= 0.26Re0.65Pr0.4
(µ
µw
)0.14
(2.1)
Re =ρupde
µ
up =(m/nc)
ρAf
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University of Mumbai CHC603 Heat Exchanger Data Book
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 Fouling factor (m2-C/W)
Process water 0.00003
Town water (soft) 0.00007
Town water (hard) 0.00017
Cooling water (treated) 0.00012
Sea water 0.00017
Lubricating oil 0.00017
Light organics 0.00010
Process fluids 0.0002 – 0.00005
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University of Mumbai CHC603 Heat Exchanger Data Book
2.2.1 Number of Transfer Units (NTU)
NTU =to − ti∆Tlm
(2.2)
Corrected mean temperature difference,
∆Tm = Ft∆Tlm (2.3)
2.2.2 Correction factor, Ft
Refer figure – 2.2
Figure 2.2: Log mean temperature correction factor for plate heat exchangers
2.3 Pressure drop
2.3.1 Pressure drop in flow through plates
∆Pp = 8jf
(Lpde
)ρu2p2
(2.4)
Lp = effective plate length, = Lv − dptjf = 0.6Re−0.3 for turbulent flow.
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University of Mumbai CHC603 Heat Exchanger Data Book
2.3.2 Pressure drop in flow through port
∆Ppt = 1.3
(ρu2pt
)2
NP (2.5)
NP = number of passes,
upt = velocity in port =m
ρAp, where Ap =
πd2pt4
2.4 Plate sizes
D
B
CE
APP
L2
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University of Mumbai CHC603 Heat Exchanger Data Book
Table 2.3: Plate dimensionsPlateNo.
MaxPressure
A B C D E L2 PP Portsize
bar mm mm mm mm mm mm mmPL01 16 460 160 336 65 85 150 – 600 pcs. × 2.4 1”PL02 16 800 160 675 65 85 150 – 600 pcs. × 2.4 1”PL03 16 837 310 590 135 132 250 – 1000 pcs. × 2.4 2”PL04 16 1066 310 819 135 132 250 – 1000 pcs. × 2.4 2”PL05 25 470 185 381 70 45 250 – 1000 pcs. × 2.7 1”PL06 25 765 185 676 70 45 250 – 1000 pcs. × 2.7 1”PL07 25 733 310 494 126 128 250 – 1000 pcs. × 2.9 2”PL08 25 933 310 694 126 128 250 – 1000 pcs. × 2.9 2”PL09 25 1182 310 894 126 128 250 – 1000 pcs. × 2.9 2”PL10 16 1080 440 650 202 200 500 – 2500 pcs. × 3.1 DN80PL11 25 1160 480 719 225 204 500 – 2500 pcs. × 3.1 DN100PL12 25 1332 480 894 225 204 500 – 3000 pcs. × 3.1 DN100PL13 25 1579 480 1141 225 204 500 – 3000 pcs. × 3.1 DN100PL14 25 1826 480 1388 225 204 500 – 3000 pcs. × 3.1 DN100PL15 25 2320 480 1882 225 204 500 – 3000 pcs. × 3.1 DN100PL16 25 1470 620 941 290 225 500 – 4000 pcs. × 3.5 DN150PL17 25 1835 620 1306 290 225 500 – 4000 pcs. × 3.5 DN150PL18 25 2200 620 1671 290 225 500 – 4000 pcs. × 3.5 DN150PL19 25 1470 620 941 290 225 500 – 4000 pcs. × 3.1 DN150PL20 25 1835 620 1306 290 225 500 – 4000 pcs. × 3.1 DN150PL21 25 2200 620 1671 290 225 500 – 4000 pcs. × 3.1 DN150PL22 25 2687 620 2157 290 225 500 – 4000 pcs. × 3.1 DN150PL23 25 1380 760 770 395 285 500 – 4000 pcs. × 3.1 DN200PL24 25 1740 760 1130 395 285 500 – 4000 pcs. × 3.1 DN200PL25 25 2100 760 1490 395 285 500 – 4000 pcs. × 3.1 DN200PL26 25 2460 760 1850 395 285 500 – 4000 pcs. × 3.1 DN200PL27 25 1930 980 1100 480 365 1780 – 5280 pcs. × 3.8 DN300PL28 25 2320 980 1490 480 365 1780 – 5280 pcs. × 3.8 DN300PL30 25 2710 980 1879 480 365 1780 – 5280 pcs. × 3.8 DN300PL31 25 3100 980 2267 480 365 1780 – 5280 pcs. × 3.8 DN300PL32 25 2500 1370 1466 672 480 1980 – 5980 pcs. × 4.1 DN500PL33 25 2855 1370 1822 672 480 1980 – 5980 pcs. × 4.1 DN500PL34 25 3211 1370 2178 672 480 1980 – 5980 pcs. × 4.1 DN500PL33 25 3567 1370 2534 672 480 1980 – 5980 pcs. × 4.1 DN500
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University of Mumbai CHC603 Heat Exchanger Data Book
Table 2.4: Pipe sizes for PHE
Outside
Diameter
Wall
Thickness
Inside
Diameter
NB DN OD - t - ID
(inches) mm (inches) (inches) (inches)
1/8 6 0.405 0.0680 0.2690
1/4 8 0.54 0.0880 0.3640
3/8 10 0.675 0.0910 0.4930
1/2 15 0.84 0.1090 0.6220
3/4 20 1.05 0.1130 0.8240
1 25 1.315 0.1330 1.0490
1 1/4 32 1.66 0.1400 1.3800
1 1/2 40 1.9 0.1450 1.6100
2 50 2.375 0.1540 2.0670
2 1/2 65 2.875 0.2030 2.4690
3 80 3.5 0.2160 3.0680
4 100 4.5 0.2370 4.0260
6 150 6.625 0.2800 6.0650
8 200 8.625 0.3220 7.9810
10 250 10.75 0.3650 10.0200
12 300 12.75 0.4060 11.9380
14 350 14 0.4380 13.1240
16 400 16 0.5000 15.0000
18 450 18 0.5620 16.8760
20 500 20 0.5940 18.8120
Pipe Size
26
Chapter 3
Condenser Design
3.1 HTC in Vertical condenser
Heat transfer coefficient for condensation on vertical tubes is given by Nusselt theory,
h = 1.47
[k3LρL (ρL − ρv) g
µ2LRe
]1/3for Re ≤ 30 (3.1)
h =Re [k3LρL (ρL − ρv) g/µ2
L]1/3
1.08Re1.22 − 5.2for 30 ≤ Re ≤ 1600 (3.2)
h =Re [k3LρL (ρL − ρv) g/µ2
L]1/3
8750 + 58Pr−0.5L (Re0.75 − 253)for Re ≥ 1600 and Pr ≤ 10 (3.3)
Re =4Γ
µL
where
Γ =m
ntπD
3.2 HTC in Horizontal Condenser
Heat transfer coefficient for condensation on horizontal single tube or a single row of tubes isgiven by Nusselt theory,
h = 1.52
[k3LρL (ρL − ρv) g
µ2LRe
]1/3for Re ≤ 3200 (3.4)
Re =4Γ
µL
where
Γ =m
ntL
kL = thermal conductivity of condensate at average film temperatureρL = density of condensate at average film temperatureρv = density of vapour
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University of Mumbai CHC603 Heat Exchanger Data Book
µL = viscosity of condensate at average film temperaturem = rate of condensation at average film temperaturent = number of tubes in tube bankL = tube length
for Nr tube rows stacked vertically,
hNr =h
N1/6r
(3.5)
for circular tube bundles used in shell-and-tube condensers,
h = 1.52
[k3LρL (ρL − ρv) g
4µLΓ∗
]1/3(3.6)
where,
Γ∗ =m
n2/3t L
Average film temperature,Tf = 0.75Tw + 0.25Tsat (3.7)
3.3 Condensation with subcooling
Sadisivan and Lienhard equation,
h
hNu=
[1 +
(0.683− 0.228
PrL
)ε
]1/4for PrL ≥ 0.6 (3.8)
where,
PrL =CpLµLkL
ε =CpL (Tsat − Tw)
λwhere
hNu = is the heat-transfer coefficient given by the basic Nusselt theory.Tsat = condensation temperatureTw = tube wall temperatureλ = latent heat of condensation.
3.4 Condensation with desuperheating
h
hNu=
[1 +
Cpv (Tv − Tsat)λ
]1/4(3.9)
where
hNu = is the heat-transfer coefficient given by the basic Nusselt theory.Cpv = specific heat of vapourTsat = condensation temperatureTv = vapour temperatureλ = latent heat of condensation.
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University of Mumbai CHC603 Heat Exchanger Data Book
3.5 Condensation in vertical tubes with vapour down-
flow
The correlation of Boyko and Kruzhilin,
h = hLo [1 + x (ρL − ρv) /ρv]0.5 (3.10)
where
x = vapour weight fractionhLo = heat-transfer coefficient for total flow as liquid
3.6 Condensation outside horizontal tubes
McNaught developed the following simple correlation for shear-controlled condensation intube bundles:
h
hL= 1.26X−0.78tt (3.11)
where,
Xtt = Lockhart-Martinelli parameter, (refer section – 4.3)hL = heat-transfer coefficient for the liquid phase flowing alone through the bundle.
(refer chapter – 1)
************
29
Chapter 4
Reboiler Design
4.1 Nucleate Boiling
4.1.1 The Forster-Zuber correlation
hnb = 0.00122k0.79L Cp0.45L ρ0.49L g0.25c ∆T 0.24
e ∆P 0.75sat
σ0.5µ0.29L λ0.24ρ0.24v
(4.1)
where,
hnb = nucleate boiling heat-transfer coefficient, Btu/h·ft2·F(W/m2·K)kL = liquid thermal conductivity, Btu/h·ft·F (W/m·K)CpL = liquid heat capacity, Btu/lbm ·F(J/kg· K)ρL = liquid density, lbm/ft3(kg/m3)µL = liquid viscosity, lbm/ft·h (kg/m·s)σ = surface tension, lbf/ft(N/m)ρv = liquid density, lbm/ft3(kg/m3)λ = latent heat of vaporization, Btu/lbm (J/kg)gc = unit conversion factor = 4.17× 108 lbm·ft/lbf·h2 (1.0 kg·m/N·s2)∆Te = Tw − Tsat, F(K)Tw = tube-wall temperature, F(K)Tsat = saturation temperature at system pressure, F(K)∆Psat = Psat(Tw)− Psat(Tsat), lbf/ft2 (Pa)Psat(T ) = 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 SIunits shown above.
4.1.2 The Mostinski correlation
In English unit,hnb = 0.00622P 0.69
c q0.7Fp (4.2)
where,
hnb = nucleate boiling heat-transfer coefficient, Btu/h·ft2·FPc = fluid critical pressure, psiaq = heat flux, Btu/h·ft2 = hnb∆TeFp = pressure correction factor, dimensionless
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University of Mumbai CHC603 Heat Exchanger Data Book
In SI units,hnb = 0.00417P 0.69
c q0.7Fp (4.3)
where,
hnb = nucleate boiling heat-transfer coefficient, W/m2·KPc = fluid critical pressure, kPaq = heat flux, W/m2 = hnb∆Te
The pressure correction factor given by:
Fp = 2.1P 0.27r +
[9 +
(1− P 2
r
)−1]P 2r (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 = 21q0.67P 0.12r (− log10 Pr)
−0.55M−0.5 (4.5)
In SI unit same as that of equation – 4.3,
hnb = 55q0.67P 0.12r (− log10 Pr)
−0.55M−0.5 (4.6)
where M is the molecular weight of the fluid.
4.1.4 The Stephan-Abdelsalam correlation
Z1 =qdBkLTsat
(4.7)
Z2 =α2LρL
gcσdB(4.8)
Z3 =gcλd
2B
α2L
(4.9)
Z4 =ρvρL
(4.10)
Z5 =ρL − ρvρL
(4.11)
dB = 0.0146θc
[2gcσ
g (ρL − ρv)
]0.5(4.12)
where,
dB = theoretical diameter of bubbles leaving surface, ft(m)θc = contact angle in degreesg = gravitational acceleration, ft/h2 (m/s2)gc = 4.17× 108 lbm·ft/lbf·h2 (1.0 kg·m/N·s2)
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University of Mumbai CHC603 Heat Exchanger Data Book
αL = liquid thermal diffusivity, ft2/s (m2/s)q ∝ Btu/h·ft2(W/m2)kL ∝ Btu/h·ft·F (W/m·K)Tsat ∝ R (K)σ ∝ lbf/ft (N/m)ρL, ρv ∝ lbm/ft3 (kg/m3)λ ∝ ft·lbf/lbm (J/kg)1 Btu = 778 ft·lbf
The heat-transfer coefficient is given by the following equation:
hnbdBkL
= 0.23Z0.6741 Z0.35
2 Z0.3713 Z0.297
4 Z−1.735 (4.13)
Fluid group Contact angle (θc) in
Water 45
Hydrocarbons (including alcohols) 35
Refrigerants (including CO2, propane, n-butane) 35
Cryogenic fluids (including methane, ethane) 1
4.1.5 Boiling mixtures
The coefficient, hideal, is an average of the pure component values that is calculated as follows:
hideal =
[n∑i=1
xihnb,i
](4.14)
where hnb,i is the heat-transfer coefficient for pure component i. So heat transfer coefficientfor mixture is,
hnb = hideal
1 +
(BR · hideal
q
)[1− exp
(−qρLλβ
)]−1(4.15)
where
BR = TD − TB = boiling rangeTD = dew-point temperatureTB = bubble-point temperatureβ = 0.0003 m/s (SI units) = 3.54 ft/h (English units)
4.1.6 Convective effects in tube bundles
The average boiling heat-transfer coefficient, hb, is expressed as follows:
hb = hnbFb + hnc (4.16)
where hnc is a heat-transfer coefficient for liquid-phase natural convection and Fb is a factorthat accounts for the effect of the thermosyphon-type circulation in the tube bundle. The
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University of Mumbai CHC603 Heat Exchanger Data Book
bundle convection factor is correlated in terms of bundle geometry by the following empiricalequation,
Fb = 1.0 + 0.1
[0.785Db
C1 (PT/Do)2Do
− 1.0
]0.75(4.17)
where,
Db = bundle diameter (outer tube-limit diameter)Do = tube ODPT = tube pitchC1 = 1.0 for square and rotated square layouts
= 0.866 for triangular layouts
For larger temperature differences, therefore, Palen suggests using a rough approximationfor 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:
qc = 0.149λ√ρv [σggc (ρL − ρv)]0.25 (4.18)
4.2.1 Mostinski correlation
Boiling on single tube. For English unit,
qc = 803PcP0.35r (1− Pr)0.9 (4.19)
where qc Btu/h·ft2 and Pc in psia.For SI unit,
qc = 367PcP0.35r (1− Pr)0.9 (4.20)
where qc W/m2 and Pc in kPa.For tube bundles, Palen presented the following correlation:
qc,bundle = qc,tubeφb (4.21)
where
qc,bundle = critical heat flux for tube bundleqc,tube = critical heat flux for a single tubeφb = bundle correction factor
= 3.1ψb for ψb < 1.0/3.1 ∼= 0.323= 1.0 otherwise
ψb = dimensionless bundle geometry parameter =πDbL
ADb = bundle diameterA = bundle surface area = ntπDoL for plain tubesDo = tube ODL = tube lengthnt = number of tubes in bundle
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University of Mumbai CHC603 Heat Exchanger Data Book
4.3 Two Phase Flow
4.3.1 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 = two-phase multiplier
(∆Pf/L)L = negative pressure gradient for liquid alone(∆Pf/L)tp = negative two-phase pressure gradient
The two-phase multiplier is a function of the parameter, X, which is defined as follows:
X =
[(∆Pf/L)L(∆Pf/L)v
]0.5(4.23)
where (∆Pf/L)v is the pressure gradient that would occur if the vapor phase flowed alone inthe conduit.The relationship between φ2
L and X was given in graphical form by Lockhart andMartinelli, and subsequently expressed analytically by Chisholm as follows:
φ2L = 1 +
C
X+
1
X2(4.24)
The constant, C, depends on whether the flow in each phase is laminar or turbulent, as shownin 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,
Xtt =
(1− xx
)0.9(ρvρL
)0.5(µLµv
)0.1
(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 (4.26)
where,
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University of Mumbai CHC603 Heat Exchanger Data Book
φ2LO = two-phase multiplier
(∆Pf/L)LO = negative pressure gradient for liquid alone(∆Pf/L)tp = negative two-phase pressure gradient
The correlation for the two-phase multiplier is the following:
φ2LO = 1 +
(Y 2 − 1
)B [x (1− x)](2−n)/2 + x2−n
(4.27)
Y =
(ρLρv
)0.5(µvµL
)n/2(4.28)
where n = 0.2314For English unit with G in units of lbm/h · ft2:
B = 1500/√G (0 < Y ≤ 9.5)
= 14250/(Y√G)
(9.5 < Y ≤ 28) (4.29)
= 399000/(Y 2√G)
(Y > 28)
For calculations in SI units, the following conversion can be used:
G(lbm/h · ft2) ≡ 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 +
3.24FH
Fr0.045We0.035(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
Fr =G2
gDiρ2tp= Froude numbar
We =G2Di
gcρtpσ= Weber number
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 (4.31)
where, x is vapour mass fraction.
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University of Mumbai CHC603 Heat Exchanger Data Book
Slip ratio,
SR =
√ρLρtp
(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,
ρtp = εvρv + (1− εv) ρL (4.34)
The Muller-Steinhagen and Heck(MSH) correlation
The correlation is reformulated in the Chisholm format of Equation – 4.26 with the two-phasemultiplier given by the following equation:
φ2LO = Y 2x3 +
[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 = SCHhnb + FxhL (4.36)
where
hb = convective boiling heat-transfer coefficienthnb = nucleate boiling heat-transfer coefficient
SCH = (1 + 2.53× 10−6Re1.17)−1
Fx = 2.35(X−1tt + 0.213
)0.736for (Xtt < 10)
= 1.0 for (Xtt ≥ 10)
Re = ReL (Fx)1.25
The heat flux is calculated as follows:
q = SCHhnb (Tw − Tsat) + hL (Tw − Tb) (4.37)
whereas convective heat transfer coefficient, hL, can be calculated using Dittus-Boelter equa-tion,
hL = 0.023 (kL/Di)Re0.8L Pr0.4L (4.38)
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University of Mumbai CHC603 Heat Exchanger Data Book
4.4.2 Critical heat flux
The following simple correlation for vertical thermosyphon reboilers was given by Palen
qc = 16070(D2/L
)0.35P 0.61c Pr0.25 (1− Pr) English Unit (4.39)
qc = 23660(D2/L
)0.35P 0.61c Pr0.25 (1− Pr) SI units (4.40)
where
qc = critical heat flux, Btu/h · ft2 (W/m2)D = tube ID, ft (m)L = tube length, ft(m)Pr = reduced pressure in tubePc = critical pressure of fluid, psia (kPa)
For flow in horizontal tubes, the dimensionless correlation of Merilo is recommended byHewitt et al.
qcGλ
= 575γ−0.34H
(L
D
)−0.511(ρL − ρvρv
)1.27
(1 + ∆Hin/λ)1.64 (4.41)
where
γH =
(GD
µL
)(µ2L
gcσDρL
)−1.58 [(ρL − ρv) gD2
gcσ
]−1.05(µLµv
)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 Film Boiling
4.5.1 Heat transfer coefficient
A combined heat-transfer coefficient, ht, for both convection and radiation can be calculatedfrom the following equation:
h4/3t = h
4/3fb + hrh
1/3t (4.43)
For saturated film boiling on the outside of a single horizontal tube,
hfbDo
kv= 0.62
[gρv (ρL − ρv)D3
o (λ+ 0.76Cp,v∆Te)
kvµv∆Te
]0.25(4.44)
Here, Do is the tube OD. hr is the radiative heat-transfer coefficient calculated from thefollowing equation:
hr =εσSB (T 4
w − T 4sat)
Tw − Tsat(4.45)
where,
ε = emissivity of tube wallσSB = Stefan-Boltzmann constant
= 5.67× 10−8 W/m2 ·K4 = 1.714× 10−9 Btu/h · ft2 · R4
If hr < hfb, Equation – 4.43 can be approximated by the following explicit formula for ht:
ht = hfb + 0.75hr (4.46)
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University of Mumbai CHC603 Heat Exchanger Data Book
4.6 Design equations
4.6.1 Number of nozzles
For a tube bundle of length L and diameter Db, the number, Nn, of nozzle pairs (feed andreturn) is determined from the following empirical equation,
Nn =L
5Db
(4.47)
4.6.2 Shell diameter
Vapour loading,
VL = 2290ρv
(σ
ρL − ρv
)0.5
(4.48)
where
VL = vapor loading (lbm/h · ft3)ρv, ρL = vapor and liquid densities (lbm/ft3)σ = surface tension (dyne/cm)
The dome segment area, SA, is calculated from the vapour loading as follows:
SA =mV
L× VL(4.49)
The segment area till semicircle is given by,
SA =D2s
8(θ − sin θ) (4.50)
θ = 2 cos−1(
1− 2h
Ds
)(4.51)
where, Ds Shell ID and h is height of the segment. When segment exceeds semicircle thesegment area is area of circle minus area of segment whose height in the circle diameter minusheight of the given segment.
4.7 Frictional losses in pipe
4.7.1 Friction factor
Reynold’s number
NRe =dvρ
µ
Friction factor in Laminar flow:
f =16
NRe
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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 for 50000 < NRe < 1× 106
ii) f = 0.0014 +0.125
NRe0.32 for 3000 < NRe < 3× 106
iii) von-Karman equation
1√f/2
= 2.5 ln(NRe
√f/8)
+ 1.75
B. For Commercial pipes (Turbulent)
i) Colebrook equation1√4f
= 2 log
(D
2κ
)+ 1.74
ii) Generalised equationf = 0.3673N−0.2314Re
4.7.2 Pressure drop in pipe
∆P = 4f
(L
d
)ρv2
2
4.7.3 Maximum gas/vapour velocity in tubes
For plain carbon steel tube in English unit,
vmax =1800√PM
(4.52)
in SI units,
vmax =1440√PM
(4.53)
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.
iii. Multiply above value with the factor√
(ρwater/ρliquid) if liquid is other than water.
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University of Mumbai CHC603 Heat Exchanger Data Book
4.7.5 Maximum velocity of two-phase flow in tubes/pipe
English unit,
vmax =
√4000
ρtp(4.54)
SI unit,
vmax =
√5924
ρtp(4.55)
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
(LinDin
)G2in
2ρL(4.56)
The subscript in refers to the inlet line to the reboiler.
PC − PB = ρL (g/gc)LBC − 4f
(LBCDt
)G2t
2ρL(4.57)
41
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 = ρtp (g/gc)LCD (4.59)
∆Pf,CD = 4f
(LCDDt
)G2t φ
2LO
2ρL(4.60)
∆Pacc,CD =G2tγ
ρL(4.61)
Fair recommends calculating ρtp at a vapour weight fraction equal to one-thirds the value atthe reboiler exit using equation – (4.34). where,
γ =(1− xe)2
1− εv,e+ρLx
2e
ρvεv,e− 1
In this equation, xe and εv,e are the vapour mass fraction and the void fraction at the reboilerexit.
Fair recommends calculating φ2LO at a vapour weight fraction equal to two-thirds the value
at the reboiler exit.
PA − PD =(G2
t −G2ex) (γ + 1)
ρL−
4fexLexG2exφ
2LO,ex
2ρLDex
(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,
m2i =
1.234D5t ρL(g/gc) (ρLLAC − ρtpLCD)
2Dt
[(γ + 1)
(Dt
Dex
)4
− 1
n2t
]
+ finLin
(Dt
Din
)5
+
(ftn2t
)(LBC + LCDφ
2LO
)+ fexLexφ
2LO,ex
(Dt
Dex
)5
(4.63)
where,
mi = tube-side mass flow rate (kg/s)nt = number of tubes in reboiler
4.8.2 Sensible heating zone
TC − TBPC − PB
=(∆T/L)
(∆P/L)(4.64)
Tsat − TAPsat − PA
= (∆T/∆P )sat (4.65)
42
University of Mumbai CHC603 Heat Exchanger Data Book
LBCLBC + LCD
∼=(∆T/∆P )sat
(∆T/∆P )sat −(∆T/L)
(∆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 =ntπDoUD∆Tm
miCpL(4.68)
Here, UD and ∆Tm are the overall coefficient and mean driving force, respectively, for thesensible heating zone.
4.8.3 Mist flow limit
Tube-side mass flux at onset of mist flow,
Gt,mist = 1.8× 106Xtt (lbm/h · ft2) (4.69)
Gt,mist = 2.44× 103Xtt (kg/s ·m2) (4.70)
********************
43
1 Heat Exchanger Specification Sheet2 Company:
3 Location:
4 Service of Unit:
5 Item No.: Prepared by:
6 Date: Rev No.: Job No.:
7 Size mm Type Connected in parallel series
8 Surf/unit(eff.) m2 Shells/unit Surf/shell (eff.) m2
9 PERFORMANCE OF ONE UNIT
10 Fluid allocation Shell Side Tube Side
11 Fluid name
12 Fluid quantity, Total kg/h
13 Vapor (In/Out) kg/h
14 Liquid kg/h
15 Noncondensable kg/h
16
17 Temperature (In/Out) C
18 Dew / Bubble point C
19 Density kg/m3
20 Viscosity cp
21 Molecular wt, Vap
22 Molecular wt, NC
23 Specific heat kJ/(kg*C)
24 Thermal conductivity W/(m*K)
25 Latent heat kJ/kg
26 Pressure mmH2O(g)
27 Velocity m/s
28 Pressure drop, allow./calc. mmH2O
29 Fouling resist. (min) m2*K/W
30 Heat exchanged kcal/h MTD corrected C
31 Transfer rate, Service Dirty Clean W/(m2*K)
32 CONSTRUCTION OF ONE SHELL Sketch
33 Shell Side Tube Side
34 Design/Test pressure kgf/cm2
35 Design temperature C
36 Number passes per shell
37 Corrosion allowance mm
38 Connections In
39 Size/rating Out
40 mm Intermediate
41 Tube No. OD Tks- avg mm Length mm Pitch mm
42 Tube type Material Tube pattern
43 Shell ID OD mm Shell cover
44 Channel or bonnet Channel cover
45 Tubesheet-stationary Tubesheet-floating
46 Floating head cover Impingement protection
47 Baffle-crossing Type Cut(%d) Spacing: c/c mm
48 Baffle-long Seal type Inlet mm
49 Supports-tube U-bend Type
50 Bypass seal Tube-tubesheet joint groove/expand
51 Expansion joint Type
52 RhoV2-Inlet nozzle Bundle entrance Bundle exit kg/(m*s2)
53 Gaskets - Shell side Tube Side
54 Floating head
55 Code requirements TEMA class
56 Weight/Shell Filled with water Bundle kg
57 Remarks
58
59
60
61
62
Company PLATE-AND-FRAME HEAT EXCHANGER DATA SHEET (SI UNITS)
PROCESS
Engineering contractor
PO No.: Doc. No.: Page 1 of
Customer: Vendor:
Project: Order/enq. No.:
Location: Model:
Item No.: Serial No.:
Service:
01 CASE HOT SIDE COLD SIDE
02 Fluid
03 Total flow (kg/s)
04 Flow per exchanger (kg/s)
05 Design temperature (max.) ( C)
06 Minimum design metal temp. ( C)
07 Design pressure [kPa (ga)]
08 Pressure drop allow./calc.- (kPa) / /
09 Wall temperature min./max. ( C) / /
10 Fouling margin a (%)
11 OPERATING DATA INLET OUTLET INLET OUTLET
12 Liquid flow (kg/s)
13 Vapour flow (kg/s)
14 Non-condensables flow (kg/s)
15 Operating temperature ( C)
16 Operating pressure [kPa (ga)]
17 LIQUID PROPERTIES
18 Density (kg/m3)
19 Specific heat capacity (kJ/kg·K)
20 Dynamic viscosity (mPa·s)
21 Thermal conductivity (W/m·K)
22 Surface tension (N/m)
23 VAPOUR PROPERTIES
24 Density (kg/m3)
25 Specific heat capacity (kJ/kg·K)
26 Dynamic viscosity (mPa·s)
27 Thermal conductivity (W/m·K)
28 Relative molecular mass (kg/kmol)
29 Relative molecular mass,
non-condensables
(kg/kmol)
30 Dew point/bubble point ( C)
31 Solids maximum size (mm)
32 Solids concentration (% volume)
33 Latent heat (kJ/kg)
34 Critical pressure [kPa (abs)]
35 Critical temperature ( C)
36
37 Total heat exchanged (kW)
38 U a (W/m2·K) Clean condition: Service:
39 LMTD ( C) /
40 Heat transfer area (m2)
41 Stream heat transfer coefficient (W/m2·K) a Fouling margin = [(Uclean /Uservice) 1] 100 % where U = Overall heat transfer coefficient (thermal transmittance).
Rev. No. Revision Date Prepared by Reviewed by