# Sutherland Formula Viscosity Calculator

## Background for Sutherland Formula Viscosity Calculator Excel Spreadsheet

Sutherland’s formula for calculating the viscosity of a gas at a specified gas temperature is shown below along with an explanation of the parameters in the equation.

The parameters in Sutherland’s formula are as follows:

To = reference temperature, K

μo = viscosity of the gas at temperature, To

C = Sutherland’s constant for the gas, K

T = the temperature of the gas, K

μ = the viscosity of the gas at temperature, T, in the same units as μo.

Example Sutherland Formula Viscosity Calculator Excel Spreadsheet

An example Sutherland formula viscosity calculator Excel spreadsheet is partially shown in the image below.  This Excel spreadsheet can be used to calculate the viscosity of a specified gas at a specified tempeerature.  This Excel spreadsheet, as well as others for fluid property calculations, is available for both U.S. or S.I. units for a very reasonable price in our spreadsheet store.

References

1. Chapman, S. & Cowling, T. G., “The Mathematical Theory of Non-Uniform Gases, 3rd Ed, 1970, Cambridge Mathematical Library.
2. National Physical Laboratory, Kaye & Laby, Tables of Physical and Chemical Constants, Chapter 2, Section 2.2, Subsection 2.2.3.
3. Bengtson, Harlan, Sutherland Law Viscosity Calculator, an informational blog article.
4. Bengtson, Harlan H., “Gas Property Calculator Spreadsheet,” an Amazon Kindle e-book.

# Gas Compressibility Factor Calculator Excel Spreadsheet

## Background for Gas Compressibility Factor Calculator Excel Spreadsheet

The compressibility factor of a gas is used in several types of calculations including calculation of real gas density.  The Ideal Gas Law, PV = nRT, can be used to calculate the density of a gas that exhibits ideal gas behavior by introducing the molecular weight of the gas and solving for gas density to give:  ρ = MW*P/R*T.
For information on the use of the ideal gas to calculate gas density, see the article, “Air Density Calculator Excel Spreadsheet.”

Conditions required for ideal gas behavior are pressure << critical pressure and/or temperature >> critical temperature.  For gases that don’t exhibit ideal gas behavior, the compressibility factor, Z can be introduced to give:     ρ = Z*MW*P/R*T.

## The Redlich-Kwong Equation of State

One possibility for a gas compressibility factor calculator Excel spreadsheet is through the use of the Redlich-Kwong equation of state, which is shown below:

A, B, and h are constants calculated as shown.  The compressibility factor, Z, can be calculated for known values of the gas temperature, T, the gas temperature, P, and the critical temperature and pressure of the gas.  The temperatures should be in K and the pressures in atm for use of the equations given above.  Calculation of Z requires an iterative calculation because the equations can’t be solved explicitly for Z.

## Example Gas Compressibility Factor Calculator Excel Spreadsheet

An example gas compressibility factor calculator Excel spreadsheet is partially shown in the image below.  This Excel spreadsheet can be used to calculate the compressibility factor of a gas, based on user input values for gas temperature, gas pressure, and the critical temperature and pressure of the gas.  This Excel spreadsheet, as well as others for fluid property calculations, is available in either U.S. or S.I. units for a very reasonable price in our spreadsheet store.

# References

1. Otto Redlich, and J.N.S. Kwong, “On the Thermodynamics of Solutions. V. An Equation of State. Fugacities of Gaseous Solutions”, Chemical Reviews 44 pp. 233-244 (1949).

2. Bengtson, Harlan H.,  Redlich Kwong Compressibility Factor Spreadsheet, an informational online blog article.