Multiply the temperature change by 7.2 x 10-6, which is the expansion coefficient for steel. Continuing the example, you would multiply 0.0000072 by 5 to get 0.000036. Multiply the product of the expansion coefficient and the temperature increase by the original length of the steel.

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6.21. 2 Thermal expansion

Thermal expansion can also be regarded as a fractional change in size of a material/substance caused by a change of temperature….Volumetric thermal expansion.

Linear thermal expansion is ΔL = αLΔT, where ΔL is the change in length L, ΔT is the change in temperature, and α is the coefficient of linear expansion, which varies slightly with temperature. The change in area due to thermal expansion is ΔA = 2αAΔT, where ΔA is the change in area.

It is made up of a coiled bimetallic strip whose one end is fixed and the other end connected to a pointer. Commonly used metals are brass and invar. When the temperature rises brass expands more than invar….THERMAL EXPANSION.

When the bimetallic strip is heated, brass expands more than steel due to higher thermal coefficient than steel. higher thermal expansion coefficient means that substance will expand more as compared to any other substance per degree rise in temperature.

In metals such as iron the forces between the atoms are stronger so it is more difficult for the atoms to move around . In brass the forces are a little weaker so the atoms are free to move about more. When the strip is heated the brass expands more than the iron so the strip beds.

The equation for the volume expansion is as follows: ΔV = Vo β ΔT, where the change in volume (ΔV) is equal to the initial volume (Vo) multiplied by the coefficient of volume expansion, β, and by the temperature increase.

When materials are heated, their size and volume increase in small increments, in a phenomenon known as thermal expansion. The coefficient ratio of thermal expansion indicates how much a material expands per 1℃ (2.2℉) rise in temperature.

Copper has the highest thermal conductivity of all commercial metals and the comments made concerning thermal conductivity of aluminum apply to copper, to an even greater degree. Copper has a relatively high coefficient of thermal expansion, approximately 50% higher than carbon steel, but lower than aluminum.

The coefficient of volume expansion for brass is 6*10^-5 and for steel is 3.6*10^-5. The coefficient of linear expansion for brass is 2*10^-5 and for steel is 1.2*10^-5.

Linear Thermal Expansion is calculated using the following formula: Where: L = Initial Length. ΔL = The change in Length. αL = Coefficient of Linear Thermal Expansion. ΔT = Change in temperature. Linear thermal expansion is the most common calculation used to estimate the expansion caused by a change in temperature.

To calculate the amount of expected thermal growth use the following formula: Thermal Growth = (T Running – T Non-Running) x h x k. T = Casing Temperature in the Plane Of The Feet. h = Height from Base plate to Shaft Centerline.