Viscosity Methods for Liquid Phase

The liquid viscosity calculation method may be selected with the drop down list box. Only the methods listed here are available for computing liquid viscosity. The keyword for each method appears in brackets []. Options for liquids include:

None [NONE]

No liquid viscosities are computed.

Pure Component Average [PURE]

Liquid viscosities are computed by appropriate averaging of the pure component values from the library.

Petroleum Correlation [PETRO]

Liquid viscosities are computed using generalized methods for hydrocarbons - not available with Electrolyte Models.

TRAPP Correlation [TRAP]

Liquid viscosities are computed with the TRAPP method.

API Correlation [API]

Liquid viscosities are computed using a correlation that accurately reproduces the data given in the API Technical Data Book - not available with Electrolyte Models.

API with Twu-Bull Mixing Rule [APIT]

This option applies the Twu-Bulls mixing rule to the viscosity nomograph in the API Technical Data Book - not available with Electrolyte Models.

SIMSCI Correlation [SIMS]

Liquid viscosities are computed using a correlation developed by SimSci for hydrocarbons and petroleum fractions - not available with Electrolyte Models.

SIMSCI with Twu-Bulls Mixing [TWUB]

Applies the recommended Twu-Bulls mixing rule from the API Technical Data Book to the SIMSCI method - not available with Electrolyte Models.

Heavy Oil Correlation [HEAV]

This is recommended for heavier hydrocarbon fluids such as black oil.

Read more about Heavy Oil Correlation for Liquid Viscosity. Not available with Electrolyte Models.

Lohrenz-Bray-Clark (Tacite) [LBC or TACI]

This is the Lohrenz-Bray-Clark prediction method for calculating liquid viscosities.

Woelflin Liquid Viscosity Correlatons

This is a set of several correlations developed for hydrocarbon and water brine emulsions.

Read more about Woelflin Liquid Viscosity Correlations.

Lohrenz-Bray-Clark

Liquid viscosities are computed by Lohrenz-Bray-Clark.

User-added Methods [U1, U2, U3, U4, or U5]

These options specify calculating liquid viscosities using a User-added subroutine (UTRAN1 - UTRAN5) that has been linked into PRO/II. Refer to the User-Added Subroutine User Guide for more information.

Kinematic Viscosity [KVIS] of Liquid Phase

Liquid viscosities are computed from the kinematic viscosity and the density. For purposes of this calculation, the density (sometimes in the form of specific gravity) is computed with the API method. In order to use this option, a KVIS method must be declared on the METHOD statement. A KVIS option is available only with the VISCOSITY(L) keyword.

KVIS methods include mixing rules that combine data for individual components to obtain a value for the bulk liquid. Each KVIS method can inter-convert between property values and index values. User-added methods may implement either or both conversions.

See Special Methods for Liquid Viscosity in the PRO/II Component and Thermophysical Properties Reference Manual for specific equations used by these methods.

See Special Stream Properties in chapter 8 of the Thermodynamic Data Keyword Manual for mixing rules used by these methods.

Simsci This is a perturbation expansion method that uses n-alkanes as a reference system. It divides the conversions between property values and index values into 3 regions and applies a different equation in each region. For region 1: KVIS <= 0.2 cS, region 2: 0.2 <KVIS < 10000 cS, region 3: KVIS >= 10000 cS. Based on data at two temperatures of 100F and 210F, it was developed to be well behaved when extrapolated.

UsForm This selects a user-defined equation-based calculation method implemented in user-added subroutine SPUSER.FOR. The method returns property values (that subsequently may be converted to Index values). Refer to the topic Subroutine SPUSER in chapter 17 of the User-Added Subroutines User Guide for a discussion of implementing these methods.

Index Uses property values of individual components to calculate an index value for each component. It then sums the indices on a weight, molar, or liquid volume basis.

UsIndex This selects a user-defined index method implemented in user-added subroutine CVUSER.FOR. The method returns Index values (that later may be converted tp property values). Refer to the topic Subroutine CVUSER in chapter 17 of the User-Added Subroutines User Guide for a discussion of implementing these methods.

Chevron It converts kinematic viscosities in centiStokes to an index that are blended on a liquid volume basis.

Maxwell It converts kinematic viscosities in centiStokes to an index that are blended on a liquid volume basis. Slightly more complex correlation than the Chevron method.

Refutas It converts kinematic viscosities in centiStokes to an index that are blended on a liquid weight basis. Similar in form to the Maxwell correlation.

NIST23 Liquid viscosities are computed using the NIST23 method.

GERG08 Liquid viscosities are computed using the GERG08 method.

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