You can select the FootInch units or Metric Units for the Design. All inputs will be in selected unit system. 
Type Name of txt file in which all process details will be written. 
Select Double Pipe or Tubular Exchanger. 
Flow in Pounds per hour or cubic feet per hour. 
You can select type of Tubular Exchanger. 
Properites of liquids in two streams. 
Physical Properties of two Streams. 
It shows flow rates on two sides. The division of Tube side flow by Shell side flow gives number of passes on tube side. 
Based on number of Passes R and S factors are calculated. With these Factor F_{T} is calculated. 
Enter Higher and Lower Values of Heat Transfer Coefficients and Dirt Factor. 
Sizes of Pipes. 
You can select either Square pitch or Triangular pitch.

After Calculating it shows number of Tubes required. 
here to see Dialog Boxes in Metric Units
How the Program Calculates?
Program first picks up flow rates, and then inlet and outlet temperatures for two streams. Out of these six values, if one is not known, program calculates it, based on other five. It also asks for permissible pressure drop on two streams. It then calculates average temperatures of two streams. Based on these average temperatures, it asks for specific heat, viscocity and specific gravity of two streams.
Liquid stream is generally placed on Shell side. Cooling water is placed on tube side, as it is more corrosive. The number of passes on tube side is ratio of flow rate on tube side to flow rate on shell side, which is rounded to even number.
It then calculates LMTD. Depending on number of passes, it calculates correction factor for LMTD, and corrects LMTD by that factor. It then asks for expected Higher and Lower value of Overall Heat Transfer Coefficient and value of dirt factor. It then asks for OD, Pitch, Thickness and Length of tube. Based on these, calculation is done. Initially programs assumes number of tubes equal to number of passes. Based on this tube count, it assigns shell diameter (as per number of passes). You can select Square or Triangular Pitch for tubes.
Calculation of number of Tubes:
For Shell: Program calculates Mass Velocity for shell by dividing shell side mass flow rate by shell cross sectional area. It then calculates equivalent diameter of tube. Based on this it calcuates Reynold's number. Based on Reynold's number, it picks up value of j_{H} for shell automatically. It then calculates Overall Heat Transfer Coefficient, h_{o} for outer side of tube.
For Tubes: Program calculates Mass Velocity for tube by dividing tube side mass flow rate by cross sectional area of tube. Based on this it calcuates Reynold's number based on inner diameter of tube. Based on Reynold's number, it picks up value of j_{H} for tube automatically. It then calculates Overall Heat Transfer Coefficient, h_{i} for inner side of tube.
It then corrects the two values for viscocity of liquids at wall temperature. Overall Heat Transfer Coefficient is then calculated based on h_{o}, h_{i} and dirt factor. The heat transfer area required is calculated by dividing heat load by LMTD and value of Overall Heat Transfer Coefficient. Dividing heat transfer area by tube's outer surface area gives the number of tubes required. If calculated tubes are more than number of tubes assumed, program increases number of tubes assumed by one and recalculates. It follows this procedure till number of assumed tubes are same as number of calculated tubes.
Calculation Pressure Drop:
For Tube: Based on Reynold's number calculated earlier, it picks up value of friction factor and calculates pressure drop.
For Shell: Based on Reynold's number calculated earlier, it picks up value of friction factor. Based on number of passes (due to baffles), it calculates pressure drop due to friction. If the shell side pressure drop is not within limit, it increases gap in baffle, till pressure drop is within limit.
If the pressure drops on both sides is within limit, design is good. Otherwise new combination of OD, Pitch, Thickness and Length of tube is tried to get the result.
Report Generated by Program
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*Process Design
Units of Calculation : Imperial
Input Values in Imperial system
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Type : Shell and Tube Heat Exchanger
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Duty : Cooling Chemical by Water
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*Input Parameters
Shell side flow rate : 175000.00 lb/h
Shell side inlet Temp : 93.00 Deg F
Shell side outlet Temp : 85.00 Deg F
Shell side Allowable Pressure Drop : 10.00 lb/sq.in.
Shell side liquid Specific Heat : 1.0000 Btu/lbDeg F
Shell side liquid Viscosity : 0.81 cP
Shell side Specific Gravity : 1.0000
Tube side flow rate : 280000.00 lb/h
Tube side inlet Temp : 80.00 Deg F
Tube side outlet Temp : 75.00 Deg F
Tube side Allowable Pressure Drop : 10.00 lb/sq.in.
Tube side liquid Specific Heat : 1.0000 Btu/lbDeg F
Tube side liquid Viscosity : 0.92 cP
Tube side Specific Gravity : 1.0000
==========================================
Stream 1 on Shell side
Number of Tube Side Passes : 2
Factor R : 1.6000
Factor S : 0.2778
Factor Ft : 0.9465
Corrected LMTD : 10.82
Dirt Factor Rd : 0.0020
Heat Transfer Load : 1400000.00 Btu/hr
==========================================
*Tube Data
Tube Outer Diameter : 3/4"
Length of Tube : 16'
Tube Thickness BWG : 18
Tube Pitch : 15/16"
Tube Configration : Triangular
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*All Calculations done in Imperial Units
Tube Side Flow Area : 0.1972 sq. ft.
Tube Side Mass Velocity : 1420218.39 ft/h
Tube Side Reynold's Number : 34659
Tube Side mean Temp : 77.50 Deg F
Tube side Heat Transfer Coefficient h : 1127 Btu/hsq. ft. Deg F
Shell Side Flow Area : 0.2562 sq. ft.
Shell Side Mass Velocity : 682968.47 ft/h
Shell Side Reynold's Number : 21776
Shell Side jH value : 84.0000
Shell Side mean Temp : 89.00 Deg F
Shell side Heat Transfer Coefficient h : 1161 Btu/hsq. ft. Deg F
Shell side c Value : 1.00
Shell side k Value : 0.36
==========================================
Number of Tubes : 154
Shell side passes : 18
Number of Baffles : 17
Recommended Shell NB : 1'4"
Gap in Baffles : 10 11/16"
==========================================
*Pressure Drop Calculations in Imperial Units
Shell side Pressure Drop
Shell Side Reynold's Number : 21776
Shell side passes : 18
Gap in Baffles : 10 11/16"
Shell side Friction Factor : 0.0018
Shell side Mass Velocity : 682968.47 ft/h
Shell ID : 1'3 1/4"
Shell Liquid specific gravity : 1.0000
Equivalent Dia of Tube : 3/4"
Shell side Pressure Drop : 7.2814 psi

Tube side Pressure Drop
Tube Side Reynold's Number : 34659
Tube side passes : 2
Tube side Friction Factor : 0.0002
Tube Liquid specific gravity : 1.0000
Tube Side Mass Velocity : 1420218.39 ft/h
Length of Tube : 16'
Inside Dia of Tube : 5/8"
Tube side Friction Loss : 3.9308 psi
Velocity Head : 0.3000 psi
Tube side Velocity Loss : 2.4000 psi
Tube side Pressure Drop : 6.3308 psi
==========================================
Summary
Type : Shell and Tube Heat Exchanger
Duty : Cooling Chemical by Water
Tube Outer Diameter : 3/4"
Length of Tube : 16'
Number of Tubes : 154
Tube Thickness BWG : 18
Tube Pitch : 15/16"
Number of Tube Side Passes : 2
Tube Configration : Triangular
Recommended Shell NB : 1'4"
Number of Baffles : 17
Gap in Baffles : 10 11/16"
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