Expansion Coefficient

Definition - What does Expansion Coefficient mean?

Expansion Coefficient, also known as coefficient of thermal expansion is the change in the size of an object (could be solid, liquid or in gaseous state) with the rate of change in the temperature. It generally measures the fractional change in the size of the object with the change in the temperature keeping the pressure constant. There are several types of expansion coefficients that are developed such as linear, volumetric and area thermal coefficients.

Petropedia explains Expansion Coefficient

Solids undergo maximum expansion when their surface temperature is increased by heating while they also contract when they are cooled. This response to the temperature change by any object is referred as coefficient of thermal expansion.

Coefficient of thermal expansion is used in-:

  • Linear thermal expansion
  • Volumetric thermal expansion
  • Area thermal expansion

The coefficient of expansion for crude oil and petroleum products is expressed by the following equation:

Where

Ko , K1 and K2 depends on the type of oil used.

Below table illustrates the volumetric coefficient of thermal expansion of various liquids obtained from refineries, petrochemical industries, etc.

Liquid

Volumetric Coefficient of Expansion

(1/K, 1/ Degree C)

(1/ Degree F)

Acetic acid

0.0011

0.00061

Acetone

0.00143

0.00079

Ethanol

0.00109

0.00061

Methyl Alcohol

0.00149

0.00083

Ammonia

0.00245

0.00136

Aniline

0.00085

0.00047

Benzene

0.00125

0.00069

Bromine

0.0011

0.00061

Calcium Chloride in 5.8% solution

0.00025

Calcium Chloride in 40.9% solution

0.00046

Carbon disulfide

0.00119

0.00066

Carbon tetrachloride

0.00122

0.00068

Chloroform

0.00127

0.00071

Ether

0.0016

0.00089

Ethyl acetate

0.00138

0.00077

Ethylene glycol

0.00057

0.00032

Dichlorodifluoromethane refrigerant (R-12)

0.0026

0.00144

normal Heptane

0.00124

0.00069

Hydrochloric acid in 33.2% solution

0.00046

Isobutyl alcohol

0.00094

0.00052

Gasoline

0.00095

0.00053

Glycerol

0.0005

0.00028

Kerosene and Jet fuel

0.00099

0.00055

Mercury

0.00018

0.0001

Methyl iodide

0.0012

0.00067

normal Octane

0.00114

0.00063

Lubricating Oil (unused engine oil)

0.0007

0.00039

Olive oil

0.0007

Paraffin oil

0.000764

0.00042

Petroleum

0.001

0.00056

normal Pentane

0.00158

0.00088

Phenol

0.0009

0.0005

Potassium chloride in 24.3% solution

0.00035

Sodium chloride in 20.6% solution

0.00041

Sodium sulfate in 24% solution

0.00041

Concentrated Sulfuric acid

0.00055

0.00031

Toluene

0.00108

0.0006

Trichloroethylene

0.00117

0.00065

Turpentine

0.001

0.00056

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