calculation

See http://cr4.globalspec.com/comment/138712

You confused me. Now I don't know what i know now how can I know what I don't know.

Sorry, but don't shoot the messenger.

Have a look at the poetry of D H Rumsfeld.

PV=nRT, nR is constant, so PV/T = PV/T ffej

I believe you are referring to the Joule-Thomson effect:

"In physics, the Joule-Thomson effect, or Joule-Kelvin effect, is a process in which the temperature of an ideal gas does not change, but the temperature of a real gas is either decreased or increased by letting the gas expand freely at constant enthalpy(which means that no heat is transferred to or from the gas, and no external work is extracted)."

http://en.wikipedia.org/wiki/Joule-Thomson_effect

http://prola.aps.org/abstract/PR/v13/i6/p438_1

Tad

Assuming an ideal gas, and constant volume, calculating the new temp will be straightforward.

T2 = (P2xT1)/P1

Remember to convert your number to SI units before performing the calculation. i.e. Temperature in Kelvin = Temp Celcius + 273.15 and Pressure in Pa = Press kgf/cm^2 x 98066.5

DesEng

If volume is not constant, when the gas expands it is doing work, hence it is losing energy. Isentropic expansion (reversible adiabatic) is typically used to calculate the result when volume is not constant, for example the output of an air compressor. I believe the following equation will approximately calculate the change in temperature where T is absolute temperature and p is absolute pressure for diatomic gases, like air. (From my old Marks Standard Handook for Mechanical Engineers).

T2/T1 = (p2/p1)^.286

Not too sure about my SI conversions, but I get T2 to be 261 deg C.

u can calculate the temp by considaring the ideal flow

and the relation of politropic procss