R-22 pressure vs temperature relation formula

[naifmbo]

Hi everybody,
Is there a formula we can use to get R-22 saturation temperature from the saturation pressure without using that ph table?
i need that formula in my contrl program.

thanks.

 

[willard3]

Why does everybody hate graphs?

ASHRAE Fundamentals, Chapt 17 has pressure enthalpy diagram and tables with everything you want to know about R22.

Took me less than 60 sec to get it

 

[sterl]

If its a polynomial you need, they are available from NIST or in the case of R-22, try Dupont's site.

They were also published in the 1969 edition of ASHRAE's refrigerant "bible".

 

[ades]

You may estimate by regression analysis coefficients for any type curve with sufficient and reliable data; its very easy with matrix operation in excel.

If you find any formula at Nist or Dupont, let me know, I couldnt.

 

[mxstar]

I use a program called Engineering Equation Solver (EES or Ease) that has the thermophysical property data for a large range of sunstances including R22 and will do the calculations you require.

 

[KiwiMace]

I do this backwards using the below - There is a formula in the dupont technical sheet (the old version in imperial units). You need to iterate this formula to reverse it, which is easily done with 'goalseek' in excel, or you can write a simple macro if you are inclined:

Saturation Temperature t
need in Rankin
T = t + 459.69

Term 1 = A
Term 2 = B/T
Term 3 = C*LOG10(T)
Term 4 = D*T
Term 5 = (E*(F-T)/(F*T))*LOG10(F-T))

Saturated Vapour Pressure
psia = 10^(C8-C9-C10+C11+C12)
psig = psia - 14.696

Fixed Coefficients
A 29.35754453
B 3845.193152
C 7.86103122
D 0.002190939044
E 305.8268131
F 686.1