Non-condensable Molecular Weight#

Non-condensable Molecular Weight = CONSTANT <integer> <float>

Description / Usage#

This card specifies the molecular weight of a species when the species is implicit in the mixture. This means that in most problems involving n+1 species, only n species are independent; i.e.,

../../_images/459_goma_physics.png

It is required when Flory-Huggins vapor-liquid phase equilibrium is considered at the material boundaries, as used in VL_POLY and in FLORY under YFLUX_EQUIL. This is used to convert units of mass fraction to mole fraction in species material balance.

CONSTANT

Model for converting mass to mole fractions.

  • <integer> - species number

  • <float> - molecular weight of the non-condensable species, usually the n+1 component in Goma convention.

Examples#

The following is an example card:

Non-condensable Molecular Weight = CONSTANT 2 36.

This example shows that two species are solved in the Goma problem explicitly: species 0 and species 1.

Technical Discussion#

In the current set up, species balance in Goma considers the species to be independent of each other. However, the mass or volume fractions of all species must add up to unity in any mixtures. This means that some properties of the last species must be entered in the material file although that component is not solved explicitly in the problem. This is the case for molecular weight, molar volume, and specific volume specifications, which are required for calculating Flory-Huggins liquid activity.

References#

No References.