1. ChemCAD Heat Exchangers
Group 9
Erika Gesso, Alex Hemmer, Evan Jacque, & Rachel Simoncic

2. Why Add a Heat Exchanger?
Recover heat that may otherwise be lost
Preheat earlier streams using this recycled heat
Preheat stream in order to reduce overall heating time
Example: preheating a stream prior to entering a reactor
Allows for reaction to activate more quickly

4. Types of Heat Exchangers
Fired Heater
Multi-Stream Exchanger

5. 2 common ways to use heat exchanger 1
Simple Heat Exchanger
Two-sided Heat Exchanger

6. Before Alteration: Input Stream
Determine input stream parameters and composition

7. Simple Heat Exchanger: Specifications
Add pressure drop
Input design parameter
Calculates Utility, LMTD

8. Simple Heat Exchangers: Utility Rating
Input service fluid T’s
Can input U and A if known
Shells and passes affect LMTD
Heat value and holdup optional

9. Simple Heat Exchangers: Economics
Calculated with U and A given
Costing varies with models
Factors defaulted if not given
Some depend on area
Identical for Two-sided HE

10. Simple Heat Exchangers
Keep in mind:
Outlet Temperature will not be achieved if U and A are provided

11. Two-sided Heat Exchangers: Specifications
Can be used for 2 process streams
Can be used to determine utility flow
1 spec for no utility, 2 for utility

12. Two-sided Heat Exchangers: Misc.
Can specify configuration, zones, passes, holdup
Calculated results from simulations

13. Fired Heat Exchanger

14. Fired Heater

15. Fired Heater Minimum : Input temperature out
Common Fuel Heating Values
Methane: 910 BTU/ft3
Propane: BTU/ft3

16. Fired Heater Cost Estimation Input Design Information
Type
Design
Material
Pressure
Can calculate automatically

17. Multi-Stream Exchangers

18. Multi-Stream Exchangers: Specifications
Specifying pressure drop not required
Can specify:
Temp. Out
Vapor Frac. Out
Heat Duty
Delta T (in-out)
Can only specify N-1 streams (i.e. for these three streams, specify two)

19. Generating Heat Curves

20. Step 1: Select UnitOp
Step 2: Specify Tube-side Inlet Stream

21. See Flow Summaries Heat Curve Parameters Number of cutting points
Countercurrent vs. Cocurrent

23. Additional Features: Tube & Shell Specifications Nozzle Specifications
Baffle Specifications
Material Specifications

24. Questions?

25. Works Cited
"Fuel Gases Heating Values." Fuel Gases Heating Values. The Engineering Toolbox, Web. 01 Feb
Putman, Richard E. "The Importance of Process Heat Exchangers in Industrial Energy Systems." ASME Digital Collection. The American Society of Mechanical Engineers. Web. 31 Jan
Weise, Lisa. "Heat Exchanger Simulation." AccessScience.Chemstations Chemstations Europe GmbH. Web. 31 Jan