O2 piping heat gain calculation - help!

[UtilityLouie]

Someone wants me to calculate how much temperature rise there is in a O2 system.

I am over thinking this calculation to the maximum because you can calculate the heat transferred to the pipe from solar heat gain and ambient conditions, but the cooler O2 gas should take that heat away and slowly heat up - changing the heat transfer rate as you go along the pipe. Right? If I could get just a little help on getting my mind right, it sure would help out!

This is O2 gas at 190 psig. I don't know what the temperature is, but it is coming directly from an ambient temperature vaporizer.

 

[abeltio]

depending on what you want to do... do you want to keep it at a certain temperature?
how long is the pipe?
is insulation out of the question?

saludos.
a.

 

[sterl]

You are correct, this should be addressed as a Mean Temperature Difference problem, and it may take an iteration or 2 to get the equations to balance...

O2-gas at 190 and almost any velocity is going to produce less resistance to heat flow then will be represented by the radiant gain and the ambient conductiivity/convection exposure...So apply those to the O/S area of the pipe in the overall U-equation, in effect ignoring the resistance of the O2. Use an estimated temperature rise for the O2 stream to derive a simple Mean Temp Difference. Calculate Q for those estimates; and run the Heat Gain against the O2 stream as m-dot Cp delta-T to see if it balances. Once you establish an estimate for the O2 temperature change, consider if that gain in temperature would effect the properties of the gas stream substantially. If not, calculate an inside film coefficient; incorporate it and pipe resistance into the U-Equation and re-calc Delta-T. Once more around the circle should about do it...