# Volumes vs. Standard Volumes vs. Standard Liquid Volumes

What are the differences in the OLI Software between Volumes, Standard Volumes and Standard Liquid volumes?

Volumes

OLI calculates the volume of a system based on its internal thermodynamic techniques. The is the volume of the system at a given temperature, pressure and composition. It is often referred to as the "Real" or "Actual" volume of the system. OLI also calculates the volume of each phase predicted.

## Volume at Standard Conditions

The is also known as the standard volume.

Volume at Standard Conditions are the calculated volume of each phase at standard condition using the compositions of each phase from previous flash calculation.

### Vapor:

Total moles and composition: Retrieved from previously equilibrated compositions at system temperature and pressure.

• Standard temperature: 15.556 oC
• Standard pressure: 1.0023 atm
• Volume is recalculated at the standard temperature and pressure.

The standard temperature and pressure can be set in the program options.

### Aqueous or Liquid-1:

Total moles and composition: Retrieved from previously equilibrated compositions at system temperature and pressure.

• Standard temperature: 25.0 oC
• Standard pressure: 1.0 atm
• Volume is recalculated at the standard temperature and pressure.

The standard temperature and pressure can be set in the program options.

### Organic or Liquid-2:

Total moles and composition: Retrieved from previously equilibrated compositions at system temperature and pressure.

• Standard temperature: 15.0oC
• Standard pressure: 1.0 atm
• Volume is recalculated at the standard temperature and pressure.

The standard temperature and pressure can be set in the program options.

## Standard Liquid Volume

Standard liquid volume is the calculated standard liquid volume based on true species. Standard liquid volume is calculated for all the phases that exist.

### An example

Standard liquid volume calculation of Liquid-1 phase (MSE), H2O: 55.5082 mole, NaCl: 1 mole, 25oC, 1 atm (using OLI Studio 9.5.4).

Standard liquid volume of material balance group (MBG) (accessible through Databank > literature >Material codes > VOLU )

MBG name Standard liquid volume of MBG, VOLU (m3)
H(+1) 1.41E-05
Na(+1) 1.82E-05
O(-2) -1.02E-05
Cl(-1) 1.72E-05

True species composition after speciation:

True species (Name) Composition (COMP), mole
H2O 55.5082
Cl-1 1
Na+1 1
H3O+1 1.33E-07
OH-1 1.33E-07
NaOH 5.30E-14
HCl 2.07E-15

Standard liquid volume of the phase calculation, considering MBG group contribution in each true species:

MBG Name Contribution Contribution Value
H(+1) 1.41E-05*(55.5082*2 + 1.33E-07*3 + 1.33E-07*1 + 5.30E-14*1 + 2.07E-15*1) 1.57E-03
Na(+1) 1.82E-05*(1*1 + 5.30E-14*1) 1.82E-05
O(-2) -1.02E-05*(55.5082*1 + 1.33E-07*1 + 1.33E-07*1 + 5.30E-14*1) -5.65E-04
Cl(-1) 1.72E-05*(1*1 + 2.07E-15*1) 1.72E-05
Volume (m3) 0.00103827
Volume (L) 1.03827