Calculating Absolute gas inlet temperature

[bigstu1]

I am curruently designing a new gas test jig for a component my company manufactures.The problem is that i need to find out out how to calculate (Ti) - the absolute gas inlet temperature in rankine before i can continue my calculation and find out if i can generate the required gas flow in CFM and what regulator to use in the system. Does the inlet temperature varies with pressure and pipe diameter? Any help here would be much appreciated.

 

[Montemayor]

bigstu1:

You're hinting a Thermodynamic process and not telling us anything about it. No one can answer your query with anything else other than questions. Why don't you just level and state all that you are trying or going to do?

No, the inlet temperature does not vary with pressure and pipe diameter - unless you do something to it or with it.

 

[mbeychok]

.
bigstu1:

Art Montemayor is correct in saying that you haven't given us enough information ... and I might add that your question is poorly worded.

Your question is worded as if you are asking us how to calculate a temperature in degrees Rankine. If that is so, degrees Rankine = 460 + degrees Fahrenheit.

Milton Beychok
(Contact me at www.air-dispersion.com)
.

 

[bigstu1]

Thank you for your response.



i am trying to perform a calculation for working out flow through a regulator. I have all the other variables in the calculation apart from (Ti) as I do not how to calculate this. The gas I am using is to be nitrogen, and the oulet pressure is to be a max of 1 bar. The flow rate is to be between 14-28 l/min (0.5 – 1.0 CFM). the flow coefficint(cv) of the regulator is 0.2 and the gas is nitrogen with a spec gravity (Sg) of 0.967 inlet pressure has not been decided

The equation is

SCFM = 13.9 x P1 x cv P1 = Inlet pressure
--------------- cv = regulator Flow coeffecint
sq root of Sg x Ti Sg = specific gravity rel to air
Ti = gas inlet temp in rankine

 

[zdas04]

bigstu1,
It is looking more and more like you are simply looking for a conversion from a measured temperature in human units to an absolute temperature. As mbeychok pointed out before your last post:

absolute temp = farenheit reading + 460 or => celcius reading + 273.

This is pretty basic stuff. The conversion is in every single reference book in my library (including a high school chemistry book I keep around for nostalgia).

You should be a lot more concerned about the equation you're using for SCFM. I know that many empirical equations allow you to ignore the square root of a unit (Rankine in this case), but it is seldom a good idea to use them without understanding their limitations. On top of that you seem to be missing a time term (to create the "M" in "SCFM") or the necessary terms to convert from flowing conditions to a "standard" flow rate.

I'm really sorry, but this feels like letting the baby teethe on a shotgun barrel.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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