Hydrogen vapor pressure

[antonio cantiani]

Hello everyone,
I'm a new CoolProp user and I'm trying to obtain some of hydrogen propeties, using the CoolProp libreries on MatLab.
For example I need the density at a given temperature, so I wrote this code

CoolProp.PropsSI('D', 'T', 18, 'P', 18.48E4, 'Hydrogen')

It seem to work properly.
the problem is with the vapor pressure: I wrote this code

 CoolProp.PropsSI('P', 'T', 18, 'Q', 0, 'Hydrogen')

It gives a result which is quite far from results obtained in other ways.

My questions are:
- Is 'Hydrogen' H2 or H (molecular hydrogen or not)?
- What 'Q' means and it is supposed to be 0 in order to obtain the vapor pressure?

thank you

[Vittorio Carosella]

Hello

I checked the results of your lines of code, which are:

CoolProp.PropsSI('D', 'T', 18, 'P', 18.48E4, 'Hydrogen')

73,53 kg/m3 = Liq. Hydrogen density 18K 1,848bar

CoolProp.PropsSI('P', 'T', 18, 'Q', 0, 'Hydrogen')

46602 Pa = Hydrogen sat pressure 18K

They are identical to values obtained from REFPROP 

These values should be fair

It is normal-hydrogen. Obviously not atomic hydrogen!!!

'Q', 0    means vapor fraction equal to zero

Regards

Carosella