Flash calculations with specified entropy and stagnation enthalpy

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Finding the properties of a stream leaking from a pressure vessel, assuming it is in thermodynamic equilibrium, requires the solution of a phase equilibrium problem with known values of component amounts, entropy, and stagnation enthalpy. If part of dynamic simulations of leaking vessels, these calculations need to be executed hundreds or thousands of times. Ideally, they should be fast and never fail, even when executed for difficult conditions, such as high pressure systems close to phase boundaries or to critical points. This paper proposes a single loop algorithm to solve flash problems with specified values of entropy and stagnation enthalpy. The results show that it is much faster than a nested loop algorithm for the same purpose, but occasionally fails to converge especially very close to phase boundaries. The nested loop algorithm succeeded in these situations however at large computational cost because of multiple phase additions and removals during the course of the iterations. A satisfactory balance of speed and reliability was obtained by favoring the single loop algorithm but, when it fails, using the nested loop algorithm as a backup procedure.

Original languageEnglish
Pages (from-to)196-204
Number of pages9
JournalFluid Phase Equilibria
Volume408
DOIs
Publication statusPublished - 25 Jan 2016

Fingerprint

flash
Enthalpy
Entropy
enthalpy
entropy
Phase boundaries
pressure vessels
backups
thermodynamic equilibrium
Pressure vessels
Phase equilibria
iteration
vessels
critical point
Thermodynamics
costs
Computer simulation
Costs
simulation

Keywords

  • Flash calculation
  • Isentropic process
  • Leaks
  • Stagnation enthalpy
  • Venting

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physical and Theoretical Chemistry
  • Physics and Astronomy(all)

Cite this

Flash calculations with specified entropy and stagnation enthalpy. / Castier, Marcelo; Kanes, Rym; Vechot, Luc.

In: Fluid Phase Equilibria, Vol. 408, 25.01.2016, p. 196-204.

Research output: Contribution to journalArticle

@article{f6a1120286da4a0fa9459be9f53d175b,
title = "Flash calculations with specified entropy and stagnation enthalpy",
abstract = "Finding the properties of a stream leaking from a pressure vessel, assuming it is in thermodynamic equilibrium, requires the solution of a phase equilibrium problem with known values of component amounts, entropy, and stagnation enthalpy. If part of dynamic simulations of leaking vessels, these calculations need to be executed hundreds or thousands of times. Ideally, they should be fast and never fail, even when executed for difficult conditions, such as high pressure systems close to phase boundaries or to critical points. This paper proposes a single loop algorithm to solve flash problems with specified values of entropy and stagnation enthalpy. The results show that it is much faster than a nested loop algorithm for the same purpose, but occasionally fails to converge especially very close to phase boundaries. The nested loop algorithm succeeded in these situations however at large computational cost because of multiple phase additions and removals during the course of the iterations. A satisfactory balance of speed and reliability was obtained by favoring the single loop algorithm but, when it fails, using the nested loop algorithm as a backup procedure.",
keywords = "Flash calculation, Isentropic process, Leaks, Stagnation enthalpy, Venting",
author = "Marcelo Castier and Rym Kanes and Luc Vechot",
year = "2016",
month = "1",
day = "25",
doi = "10.1016/j.fluid.2015.09.006",
language = "English",
volume = "408",
pages = "196--204",
journal = "Fluid Phase Equilibria",
issn = "0378-3812",
publisher = "Elsevier",

}

TY - JOUR

T1 - Flash calculations with specified entropy and stagnation enthalpy

AU - Castier, Marcelo

AU - Kanes, Rym

AU - Vechot, Luc

PY - 2016/1/25

Y1 - 2016/1/25

N2 - Finding the properties of a stream leaking from a pressure vessel, assuming it is in thermodynamic equilibrium, requires the solution of a phase equilibrium problem with known values of component amounts, entropy, and stagnation enthalpy. If part of dynamic simulations of leaking vessels, these calculations need to be executed hundreds or thousands of times. Ideally, they should be fast and never fail, even when executed for difficult conditions, such as high pressure systems close to phase boundaries or to critical points. This paper proposes a single loop algorithm to solve flash problems with specified values of entropy and stagnation enthalpy. The results show that it is much faster than a nested loop algorithm for the same purpose, but occasionally fails to converge especially very close to phase boundaries. The nested loop algorithm succeeded in these situations however at large computational cost because of multiple phase additions and removals during the course of the iterations. A satisfactory balance of speed and reliability was obtained by favoring the single loop algorithm but, when it fails, using the nested loop algorithm as a backup procedure.

AB - Finding the properties of a stream leaking from a pressure vessel, assuming it is in thermodynamic equilibrium, requires the solution of a phase equilibrium problem with known values of component amounts, entropy, and stagnation enthalpy. If part of dynamic simulations of leaking vessels, these calculations need to be executed hundreds or thousands of times. Ideally, they should be fast and never fail, even when executed for difficult conditions, such as high pressure systems close to phase boundaries or to critical points. This paper proposes a single loop algorithm to solve flash problems with specified values of entropy and stagnation enthalpy. The results show that it is much faster than a nested loop algorithm for the same purpose, but occasionally fails to converge especially very close to phase boundaries. The nested loop algorithm succeeded in these situations however at large computational cost because of multiple phase additions and removals during the course of the iterations. A satisfactory balance of speed and reliability was obtained by favoring the single loop algorithm but, when it fails, using the nested loop algorithm as a backup procedure.

KW - Flash calculation

KW - Isentropic process

KW - Leaks

KW - Stagnation enthalpy

KW - Venting

UR - http://www.scopus.com/inward/record.url?scp=84941695637&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84941695637&partnerID=8YFLogxK

U2 - 10.1016/j.fluid.2015.09.006

DO - 10.1016/j.fluid.2015.09.006

M3 - Article

VL - 408

SP - 196

EP - 204

JO - Fluid Phase Equilibria

JF - Fluid Phase Equilibria

SN - 0378-3812

ER -