TY - JOUR
T1 - Construction of a Minimum Energy Path for the VT Flash Model by the String Method Coupled with the Exponential Time Differencing Scheme
AU - Zhang , Yuze
AU - Li , Yiteng
AU - Zhang , Lei
AU - Sun , Shuyu
JO - Communications in Computational Physics
VL - 5
SP - 1529
EP - 1544
PY - 2021
DA - 2021/10
SN - 30
DO - http://doi.org/10.4208/cicp.OA-2021-0024
UR - https://global-sci.org/intro/article_detail/cicp/19939.html
KW - VT flash, Peng-Robinson equation of state, minimum energy path, string method, Rosenbrock-type exponential time differencing scheme.
AB - <p style="text-align: justify;">Flash calculation plays significant roles in petroleum and chemical industries. Since Michelsen proposed his milestone studies in 1982, through several decades
of development, the current research interests on flash calculation have been shifted
from accuracy to efficiency, but the ultimate goal remains the same; that is accurate
determination of equilibrium phase amounts and compositions at a given condition.
On the other hand, finding the transition route and its related saddle point is often
crucial to understand the whole energy landscape of flash models, which would provide new insights for designing numerical algorithms or optimizing existing ones. In
this study, an efficient numerical approach is developed by coupling the string method
with the exponential time differencing (ETD) scheme to investigate the minimum energy paths and first-order saddle points of VT flash models with Peng-Robinson equation of state. As a promising alternative to the conventional approach, VT flash calculates phase equilibria under a new variable specification of volume and temperature. The Rosenbrock-type ETD scheme is used to reduce the computational difficulty caused by the high stiffness of the model systems. The proposed ETD-String
method successfully calculates the minimum energy paths of single-component and
two-component VT flash models with strong stiffness. Numerical results also show
good feasibility and accuracy in calculation of equilibrium phase amounts and compositions.</p>