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[techno_chrat]

Hello, I have recently started designing cooling system, having experience in manufacturing and maintenance area. We have got analysis done for a recent project for a air cooled heat exchanger. I am sharing the report as follows. Kindly interpret the runtime message and errors.

Process Conditions
Outside
Tubeside
Fluid name
CHARGE AIR
20% RPAM700AF fluid + 80% water
Fluid condition
Sens. Gas
Sens. Liquid
Total flow rate
(1000-kg/hr)
6.150
52.000
Weight fraction vapor, In/Out
1.0000
1.0000
0.0000
0.0000
Temperature, In/Out
(Deg C)
350.00
45.00
25.00
45.00
Skin temperature, Min/Max
(Deg C)
32.65
141.08
27.39
66.17
Pressure, Inlet/Outlet
(kgf/cm2A)
6.118
6.114
4.079
2.904
Pressure drop, Total/Allow
(kgf/cm2) (kgf/cm2)
3.93e-3
5.10e-3
1.175
0.510
Midpoint velocity
(m/s)
2.35
3.63
- In/Out
(m/s)
2.21
3.65
Heat transfer safety factor
(--)
1.0000
1.0000
Fouling
(m2-hr-C/kcal)
0.000349
0.000116
Exchanger Performance
Outside film coef
(kcal/m2-hr-C)
96.98
Actual U
(kcal/m2-hr-C)
63.759
Tubeside film coef
(kcal/m2-hr-C)
9276.6
Required U
(kcal/m2-hr-C)
63.510
Clean coef
(kcal/m2-hr-C)
72.021
Area
(m2)
70.737
Hot regime
Sens. Gas
Overdesign
(%)
0.39
Cold regime
Sens. Liquid
Tube Geometry
EMTD
(Deg C)
105.3
Tube type
Continuous Fin
Total duty
(MM kcal/hr)
0.708
Tube OD
(mm)
12.000
Unit Geometry
Tube ID
(mm)
10.000
Bays in parallel per unit
1
Length
(mm)
850.000
Bundles parallel per bay
1
Area ratio(out/in)
(--)
12.473
Extended area
(m2)
70.737
Layout
Staggered
Bare area
(m2)
6.775
Trans pitch
(mm)
24.000
Bundle width
(mm)
404.
Long pitch
(mm)
20.784
Nozzle
Inlet
Outlet
Number of passes
(--)
4
Number
(--)
1
1
Number of rows
(--)
14
Diameter
(mm)
77.927
77.927
Tubecount
(--)
231
Velocity
(m/s)
2.98
3.01
Tubecount Odd/Even
(--)
16 /
17
R-V-SQ
(kg/m-s2)
9025.0
9103.2
Material
Copper/nickel 70/30
Pressure drop
(kgf/cm2)
0.051
0.032
Fin Geometry
Fan Geometry
Type
None
No/bay
(--)
0
Fins/length
(fin/meter)
472.4
Fan ring type
Fin root
(mm)
12.500
Diameter
(mm)
0.
Height
(mm)
Ratio, Fan/bundle face area
(--)
0.0000
Avg. thickness
(mm)
0.150
Driver
(kW)
-
/
-
Over fin
(mm)
0.000
Tip clearance
(mm)
0.000
Efficiency
(%)
85.0
Efficiency
(%)
0.0000
Area ratio (fin/bare)
(--)
10.4
Fans turned-down
(--)
No Fans
Material
Copper
Airside Velocities
Actual
Standard
Thermal Resistance, %
Face
(m/s)
1.49
Air
65.74
Maximum
(m/s)
3.83
Tube
8.57
Flow
(100 m3/min)
0.306
Fouling
11.47
Velocity pressure
(mmH2O)
0.000
Metal
14.21
Bundle pressure drop
(mmH2O)
39.329
Bond
0.00
Bundle flow fraction
(--)
1.000
Bundle
100.00
Airside Pressure Drop, %
Louvers
0.00
Ground clearance
0.00
Fan guard
0.00
Hail screen
0.00
Fan ring
0.00
Fan area blockage
0.00
Steam coil
0.00

Simulation-Vertical economizer countercurrent to crossflow
Unit ID 100 - WARNING MESSAGES (CALCULATIONS CONTINUE)
General
The hot and cold fluid duties differ by 69.2793 percent. (MN 4087)
The heat duty calculated from the process conditions differs from the specified value by 49.71 percent. Check the
specified process conditions and physical properties. (MN 4000)
The duty calculated from the hot fluid process conditions is 5.382E11 MW ( 1836 M Btu/hr). (MN 4075)
The duty calculated from the cold fluid process conditions is 1.109E12 MW ( 3783 M Btu/hr). (MN 4073)
The specified heat duty is 5.500E11 MW ( 1877 M Btu/hr). (MN 4088)
The required heat duty is 5.500E11 MW ( 1877 M Btu/hr). The percent overdesign is based on this value. (MN
4089)
Thermal & Hydraulic
The calculated pressure drop for the cold fluid exceeds the allowable pressure drop by 130.5276%. (MN 8017)
Geometry, Mechanical Design, and Vibration
The specified bundle width is 87. percent of the minimum bundle width calculated based on the tube pitch and the
number of tubes in each row. The bundle width entered was ignored. Check the number of tubes per row and the
bundle width entered. If necessary, correct the values and rerun the case. (MN 3123)
The specified ground clearance is less than the recommended minimum per API 661, Section 7.2.1. For this case, the
recommended minimum is .05659 m. (MN 3512)
Fluid Properties
The HTRI property correlations used for the cold fluid are being accessed at temperatures beyond the valid
temperature range of the correlations. (MN 5085)
The maximum process temperature is outside the correlational range of the thermal conductivity correlation. The
thermal conductivity was calculated at the temperature limit. For tube metal number 34 this temperature limit is 391.7
F. (MN 5088)
The physical properties of the cold fluid have been extrapolated beyond the valid temperature range. Check the
calculated values. The thermal analysis requires properties at bulk and skin/wall temperatures. (MN 5033)

[latexman]

First, I've never run HTRI, but I've had lots of experience calculating HXs and analyzing other systems that calculate HXs.  Second, be sure you and your company's input to this analysis is not the source of all the errors and messages!  If not, I would throw this report in the dust bin, and get a different contractor to work on it.  There are a lot of BIG red flags.  "The hot and cold fluid duties differ by 69.2793 percent" - way off!  Danger, Will Robinson!  "The heat duty calculated from the process conditions differs from the specified value by 49.71 percent. Check the specified process conditions and physical properties" - again, way off!  "The HTRI property correlations used for the cold fluid are being accessed at temperatures beyond the valid temperature range of the correlations" - physical properties are being EXTRAPOLATED, that may not be good!

 

If you proceed with this, the RISK is on YOU.  Don't let others substandard work put you at risk.

 

Next time just attach the PDF or DOC file.  I bet the formatting on that was more intuitive.