che_february-2025 - 26

FIGURE 9. Input data (top) and output data (bottom)
are shown for Example 7, for four choking
points in two parallel flow paths
(7)
Concluding remarks
Important concepts from a 25-yearold
article in Chemical Engineering
are clarified and reinforced. The
seven simplified examples in this
article demonstrate all the different
types of sonic choking configurations
with closed-form solutions in
Excel. Accounting for real-world
gas-flow effects (such as heat
transfer) is crucial to obtain accurate
predictions. Advice on evaluating
commercial software for compressible
flow analysis is given. Engineers
are cautioned to question common
compressible flow calculation " rules
Call the
Solids Mixing
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Applications:
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Proteins ∙ Resins ∙ Vitamins
of thumb, " such as the so-called " 40% pressure drop
rule. " Other " rules of thumb " that often lead to confusion
are found in the original article.
n
Edited by Scott Jenkins
References
1. Walters, T. W., Gas-flow Calculations: Don't Choke, Chem. Eng., January 2000.
2. Walters, T. W., A Comprehensive Discussion of Sonic Choking In Pipe Systems For Steady, Compressible
Flow, presented at the 2024 ASME Pressure Vessel and Piping Conference, PVP2024123592,
July 28 to August 2, 2024.
3. Walters, T.W., A Comprehensive Discussion of Sonic Choking In Pipe Systems For Steady, Compressible
Flow, auxiliary data files, https://www.aft.com/technical-papers/a-comprehensive-discussion-of-sonic-choking-in-pipe-systems-for-steady-compressible-flow
(2024).
4. AFT Arrow 10, Applied Flow Technology, Colorado Springs, Colo., 2024.
5. Bejan, A., " Advanced Engineering Thermodynamics, " 4th Ed., 2016, pp. 169-170.
Author
Trey Walters, P.E., is the founder and chairman of Applied
Flow Technology (AFT; 2955 Professional Place, Colorado
Springs, CO 80904; Phone: 719-686-1000; Email: treywalters@aft.com).
His role today is working with AFT team
members and customers to deliver industry-leading fluidtransfer-system
simulation solutions. He has developed commercial
software products on a variety of fluid system applications
including compressible flow in pipe network systems.
He has managed and performed consulting projects in numerous
process industries. He holds B.S. and M.S. degrees
in mechanical engineering from the University of California, Santa Barbara. He is a
Fellow of the American Society of Mechanical Engineers (ASME).
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