Water pressure over critical point

[beerbaron]

I'm looking for a formula to calculate water pressure over it's critical point. I have found no informations on how the gas behaves after it. I would need some formula that could give me water pressure for a range of 400 celcius to 1000 celcius.

Thanks
BeerBaron

 

[25362]

You need a liquid or a solid to speak about vapor pressures. Above their critical point fluids behave as gases.

Given a pressure and a temperature, in the range of temperatures of interest, you may find the other properties of supercritical water by visiting this site:

http://webbook.nist.gov/chemistry/

Press for name > water > fluid properties

 

[katmar]

The critical temperature is defined as the temperature above which a substance cannot be liquified by pressure alone.

This means that above the critical temperature (374.1 C for water) there is no correlation between the pressure and temperature the way there is for saturated conditions. If the temperature of water is above 374.1 C the pressure can be anything at all, and the water will still be in the gaseous state.

For any unique combination of P & T above the critical point you can find the other physical properties via a source like NIST (mentioned by 25362).

 

[sailoday28]

My experience is that the equations for steam/water are available in the form of A, the availability as of function of specific volume and Temperature.

Given A=U-TS where A, is availability, U, the spec internal energy, T the temp and S, the spec entropy, The properties are readily calculable.
ASME and NIST formulations are available with the above formulations.

 

[beerbaron]

Thanks guys, your help is appreciated

BeerBaron