Bell Method Example 7 5

This worksheet worksheet allows calculation calculation of the Overall Overall Heat Transfer Transfer Coefficient and and pressure pressure drops in a TEM Data input input corresp correspond onds s to yello yellow w cells cells and and the the tube tube array array must be selec selected ted in in the the list box. box. Results Results are s Process Data tube side Flowrate (kg/s) Inlet Temp. (°C) Outlet Temp. (°C) Inlet Pressure (bar abs) Q= Heat Duty (W ) Ther Therma mall Bala Balanc nce e check Density (kg/m3) Viscosity (cp) Specific Heat. (J/kg.K) Thermal Conduct. (W /m.K) Visc at wall temperature (cp) Pr

shell side

38.88 40 60 4 1664064

33.33 AUX 104 85 3 1671833

OK- error <2% 716 0.62 2140 0.129 0.59 10.29

578 0.16 2640 0.0917 0.16 4.61

Tube side Calculations at= Flow Area 0.0401 Gt= mass velocity 970.2 Ret= Reynolds Number 24568 hi= internal coeff. 1327 hio= 1096 friction factor 0.00758 Pressure drop 16099 Shell side calculations- Bell method effective number of tubes rows Total number of tubes rows correction Sm=Cross flow area Gm= Mass velocity Rem  j=Colburn Coefficient FBP=By pass fraction alfa by pass correction for h r Sw window correction factor STB=tube-baffle leakage area SSB=shell baffle leakage area SL= total leakage area SL/Sm= (1-hL/hNL)o 1-hL/hNL hL/hNL ho shell side friction factor

m2 kg/m2/s

44 45

(s N= Number of tubes pe Ntw= Ntw= Numbe Numberr of tubes tubes i NCL=Number of tubes i NBT= Number of tubes the baffle NC= Number of tubes r consecutives baffl sigm sigma= a=se sepa para rati tion on betw betw DS= Shell Diameter   DB=Baffle Diameter  BC= Baffle cut A= Baffle central angle i Do= Tubes external dia Di= Tubes internal dia DBT=Baffle holes diam Pt= Tubes separation ( c= clearance between t n= number of tube pass NB= Number of baffles NS= Number of sealing L= tubes length B= Baffles spacing

W/ W /m2K W /m2K Internal fouling ressista External fouling ressista

N/m2 334 1 0.0491 678.3 80544 3.76E-03 0.390 1.35 0.8426 0.1812 0.0356 1.1251 0.0083 0.0030 0.0112 0.2288 0.2029 0.2567 0.7433 1714.8 0.0908

Select the tubes array m2 kg/s.m2

Ns/0.5*Nc 0.307692 m2 m2 m2 m2 m2

U= Overall heat transfe Tubeside pressure drop Shellside pressure drop W all temperature calcul

W /m2K 1/(1/hio+Rfi)=

alfa2 by pass correction for deltap (deltap)BP vZ Nw (deltap)w (1-deltapL/deltapNL)o (1-deltapL/deltapNL) deltapL/deltapNL deltap shell

4 0.602 1131.3 1.38 5.54 2921 0.398 0.503 0.497 36886

1/(1/ho+Rfo)= N/m2 m/s

Wall mean temp

N/m2

Number of shells in series

N/m2

1

Heat transfer   Total area 105.4 LMTD Q % Overdesign

44.5 1894475 14%

A type E shell and tubes heat exchanger using Bell-Delaware method. hown in cells K48 to K50 GEOMETRIC DATA e drawing at right) r shell n window n central row crossing

 

414 75 21 339

ws between s edges en rows

       

in degrees meter de tubos ter itch) bes es strips pairs

   

ce(m2.K/W) nce

coefficient calculated per shell per shell  

13 0.022 m 0.609 m 0.6043 m 0.15225 m 120 0.019 m 0.0157 m 0.0198 m 0.0254 m 0.0064 2 17 2 4.267 m 0.234 m

0.0005 0.0004

417.5 W/m2K 16099 N/m2 36886 N/m2

ation 708 W/m2K

Ts=shell side fluid mean temp.

94.5 °C

1017 W/m2K

Tt=Tubeside fluid mean temp.

50 °C

76.24 °C

DPt DPc

0.217

16099 Pa 36886 Pa

m2 ºC W

Ft

0.97

MTD

43.0 ºC

LMTD Correction factor Ft Ft T1

104

T2

85.0

t1

40

t2

60.0

R

1.0

S

0.31

Number of e carcasas Tube passes FT

1 2 0.967152

Rem<100  j=a*Rem^b a 1 2 3 4 5 3

array triangle (30°) Pt/D= 1.25 Square Pt/D=1.25 Rotated Square Pt/D=1.25 triangle (30°) Pt/D= 1.5 Square Pt/D=1.5 Selected array For Rem =

1.81 0.97 1.81 1.34 0.88 1.81

80544.11

j =

Coefficients for f calculation - ln

a 1 2 3 4 5 3

arreglo triángulo (60°) Pt/D= 1.25 Cuadrado Pt/D=1.25 Cuadro rotado Pt/D=1.25 triángulo (60°) Pt/D= 1.5 Cuadrado Pt/D=1.5 Arreglo seleccionado Coefficients for Rem

4.376 3.923 3.923 3.196 3.04 3.923 80544.11

Calculation of friction factor and J factor  coefficients for J calculation 100
1.7 3.29 0.32 0.37 1.61 0.32

-1.25 -1.9 -0.76 -0.56 -1.34 -0.76

Rem>3000 j=aRem^b a b

0.065 0.121 0.025 0.0087 0.082 0.025

0.275 0.275 0.275 0.275 0.275 0.275

-0.38 -0.38 -0.38 -0.38 -0.38 -0.38

3.76E-03

 

(f)=a+blnRem+c*(lnRem)^2+d*(lnRem)^3 Rem<100

100
b

b

c -1.025 -0.984 -0.984 -1.176 -1.13 -0.984

d 0 0 0 0.0557 0.031 0 a = b= c= d=

a 0 0 0 0 0 0 6.3 -2.403 0.226 -0.00721

5.293 3.871 6.3 3.472 -8.015 6.3

c -1.864 -0.498 -2.403 -1.547 5.152 -2.403

f =

1300
0.1584 -0.2052 0.226 0.1425 -1.166 0.226

0.090804

a -0.00472 0.0221 -0.00721 -0.00454 0.0771 -0.00721

b 5.293 3.871 6.3 3.472 -6.666 6.3

-1.864 -0.498 -2.403 -1.547 1.152 -2.403

<3000 c

Rem>3000 d

0.1584 -0.2052 0.226 0.1425 -0.0981 0.226

a -0.00472 0.00221 -0.00721 -0.00454 0.00237 -0.00721

b 5.293 -7.907 6.3 3.472 -6.666 6.3

c -1.864 1.774 -2.403 -1.547 1.152 -2.403

d 0.1584 -0.16 0.226 0.1425 -0.0981 0.226

-0.00472 0.00407 -0.00721 -0.00454 0.00237 -0.00721