R407C pressure-temperature formula.

[Berenger]

Good morning.

I am setting up a spreadsheet for the readings off our chilled water plant. I want to set it up so that TSAT for the condensor and chiller is automatically generated from the suction and discharge pressures. Does anyone know the formula to convert R407C pressure to temperature?

Thanks in anticipation.

[Aik]

There is a conversion table, but really I don't know formula for this gas.
There is a formula for ideal gas:
p*V=m/M*RT
p - pressure [Pa]
V- volume [m^3]
m - mass [kg]
M- molar mass [kg/moth]
R=8,31 [J/(moth*K)]
T- temperature [K]

[tbirdtbird]

Try this: P-T chart for 407C is toward the bottom

http://www.refrigerants.com/pics/ptchart.pdf

[SteinarN]

I did make an Excell cheet for conversion of R404A pressure to temp some time ago. It is not complete in the sense it is probably necessarry to make another element like +POWER(F10;?)*? to make it accurate for higher temperatures. Currently it is acurate to within 0,6C for most of the range from -47C up to about +20C. Fine tuning the constants should probably make it more accurate. The result is temperature in degres Kelvin.

The first formula is how the result cell looks in my excell sheet for validation. The next formula is how it may look in say a PLC.

F10 is the pressure in Bar, absolute.
I10 is a constant. This is the most "senior" constant.
All the other non cell numbers is also constants. I have derived this formula by try and error so it is most likely it exists both simpler formulas as well as more acurate formulas. Altering the constants will make it correct for other refrigerants.


LOG(F10;I10)*J10+L10+O10


LOG(F10;5)*258,2+POWER(F10;1,8)*0,58+POWER(F10;3)*-0,187

[Brian_UK]

If you want the formulae used by DuPont then download this pdf file...

http://www2.dupont.com/Refrigerants/...o_prop_eng.pdf

The above is English units, if you want SI then select from the list here..

http://www2.dupont.com/Refrigerants/...rature.html#pt

[rkmoorthy]

thanks for that above information