### Abstract

A new algorithm to find the phase equilibrium conditions in systems with specified values of internal energy, volume, and number of moles of each component present (isochoric-isoenergetic flash problem) is proposed. The core of the procedure consists of maximizing the system entropy by iterating on the values, in each phase, of internal energy, volume, and number of moles of each component. Analytical expressions for the physical properties and derivatives required by the calculations were generated by computer algebra. The algorithm tests for the possible need to add or remove phases during the course of iterations. The paper discusses possible numerical difficulties during application of the procedure and how to overcome them. The algorithm has shown to be robust and capable of solving multiphase equilibrium problems, avoiding trivial solutions.

Original language | English |
---|---|

Pages (from-to) | 7-17 |

Number of pages | 11 |

Journal | Fluid Phase Equilibria |

Volume | 276 |

Issue number | 1 |

DOIs | |

Publication status | Published - 15 Feb 2009 |

Externally published | Yes |

### Fingerprint

### Keywords

- Algorithm
- Equations of state
- Flash
- isochoric-isoenergetic
- Optimization
- Phase equilibrium

### ASJC Scopus subject areas

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

### Cite this

**Solution of the isochoric-isoenergetic flash problem by direct entropy maximization.** / Castier, Marcelo.

Research output: Contribution to journal › Article

*Fluid Phase Equilibria*, vol. 276, no. 1, pp. 7-17. https://doi.org/10.1016/j.fluid.2008.10.005

}

TY - JOUR

T1 - Solution of the isochoric-isoenergetic flash problem by direct entropy maximization

AU - Castier, Marcelo

PY - 2009/2/15

Y1 - 2009/2/15

N2 - A new algorithm to find the phase equilibrium conditions in systems with specified values of internal energy, volume, and number of moles of each component present (isochoric-isoenergetic flash problem) is proposed. The core of the procedure consists of maximizing the system entropy by iterating on the values, in each phase, of internal energy, volume, and number of moles of each component. Analytical expressions for the physical properties and derivatives required by the calculations were generated by computer algebra. The algorithm tests for the possible need to add or remove phases during the course of iterations. The paper discusses possible numerical difficulties during application of the procedure and how to overcome them. The algorithm has shown to be robust and capable of solving multiphase equilibrium problems, avoiding trivial solutions.

AB - A new algorithm to find the phase equilibrium conditions in systems with specified values of internal energy, volume, and number of moles of each component present (isochoric-isoenergetic flash problem) is proposed. The core of the procedure consists of maximizing the system entropy by iterating on the values, in each phase, of internal energy, volume, and number of moles of each component. Analytical expressions for the physical properties and derivatives required by the calculations were generated by computer algebra. The algorithm tests for the possible need to add or remove phases during the course of iterations. The paper discusses possible numerical difficulties during application of the procedure and how to overcome them. The algorithm has shown to be robust and capable of solving multiphase equilibrium problems, avoiding trivial solutions.

KW - Algorithm

KW - Equations of state

KW - Flash

KW - isochoric-isoenergetic

KW - Optimization

KW - Phase equilibrium

UR - http://www.scopus.com/inward/record.url?scp=57749087846&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=57749087846&partnerID=8YFLogxK

U2 - 10.1016/j.fluid.2008.10.005

DO - 10.1016/j.fluid.2008.10.005

M3 - Article

VL - 276

SP - 7

EP - 17

JO - Fluid Phase Equilibria

JF - Fluid Phase Equilibria

SN - 0378-3812

IS - 1

ER -