## liquid thermal expansion calc - help needed

## liquid thermal expansion calc - help needed

(OP)

I have density data that shows this liquid is 55.9 lb/ft3 at 200'F and 53.7 lb/ft3 at 300'F. What is the thermal expansion coefficient (beta)?

I have tried inverting the density adn calculating (0.0186-0.0179)/100 = 0.000007 but that number seems too small compared to similar fluids. What is the right way to do this?

TYIA,

Heater Guy

I have tried inverting the density adn calculating (0.0186-0.0179)/100 = 0.000007 but that number seems too small compared to similar fluids. What is the right way to do this?

TYIA,

Heater Guy

## RE: liquid thermal expansion calc - help needed

B = 1/V ( dV/ T)

where B = thermal expansion coefficient, V = Volume, dV = change in Volume, and T = change in temperature.

Your method looks right. Have you checked the units?

## RE: liquid thermal expansion calc - help needed

beta = (dV/V

_{0})/dT (PS: I am using d instead of delta and this is not a differentiation)## RE: liquid thermal expansion calc - help needed

It seems we have posted at the same time.

## RE: liquid thermal expansion calc - help needed

I hope heaterguy is now satisfied with the cubic thermal expansion value estimated by quark in 1/

^{o}F. When using^{o}C the result should be multiplied by 1.8 .## RE: liquid thermal expansion calc - help needed

## RE: liquid thermal expansion calc - help needed

The information you provided is not enough to calculate the term BETTA. Unless, the pressure at the two conditions is the same.

## RE: liquid thermal expansion calc - help needed

In theory sailoday28 is right. The definition of the cubic thermal expansion β, sometimes called alpha, is:

_{P}However, the isothermal compressibility values

_{T}are quite small when the liquids are well below their normal boiling points, usually lower than 2×10

^{-4}/atm, to sensibly affect the definition given by quark.## RE: liquid thermal expansion calc - help needed

Can you explain in layman terms--How did you display the partials?

Thanks

## RE: liquid thermal expansion calc - help needed

Knowing the liquid might give more of a handle on determining Betta.

## RE: liquid thermal expansion calc - help needed

## RE: liquid thermal expansion calc - help needed

ρ/Δt)(1/ρ_{ave})which in this case would result in:

^{o}F## RE: liquid thermal expansion calc - help needed

I was using either of the densities, but it makes more sense to use the average of the two. Thanks.

heaterguy