Title: Efficient and robust phase-split computations in the internal energy, volume, and moles (UVN) space

Journal Article · · Fluid Phase Equilibria
 [1];  [2];  [3]
  1. Texas A & M Univ., College Station, TX (United States)
  2. Reservoir Engineering Research Inst., Palo Alto, CA (United States); Rice Univ. Houston, TX (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
+ Show Author Affiliations

Phase-split computations in an isolated system, which in general may be defined as one where the total internal energy (U), volume (V), and the number of moles (N = N1, N2,..., Nn) of the components are fixed at some specified set of values, involves the determination of the temperature (T), pressure (P), plus the amount and composition of the various phases that constitute the system. A simpler, but analogous problem is one where T, P, and N are specified instead. In TPN space, one may first perform a stability analysis to determine whether the system is stable, meaning whether at equilibrium it will split up into multiple phases or remain in single phase. If the single-phase state is unstable, the stability analysis reliably provides a good set of initial guesses in the subsequent phase-split computations. In UVN space, however, we demonstrate that the stability analysis (which is the main subject of our earlier study [1]) may not in general provide good enough initial guesses; we offer alternative strategies for setting up good initial guesses. Furthermore, we show that a combination of successive substitution iteration (SSI) and Newton's method---two iterative methods that are prevalent in the literature in TPN space---facilitates a robust and efficient algorithm for phase-split computations in isolated systems. Finally, this combination has so far not been applied in UVN space.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE; USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344
OSTI ID:
1735795
Journal Information:
Fluid Phase Equilibria, Journal Name: Fluid Phase Equilibria Journal Issue: na Vol. 526; ISSN 0378-3812
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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