Calculating Heat in Exhaust Pipes: Internal Temperature

[Tweaked9107]

Im trying to calculate how hot the gas inside my exhaust pipe is. I have several numbers and a calculation on how to find heat transfer, but no way of finding inside temperature if i don't already know it.

Length= 0.5m
k (heat coefficient for stainless steel)= 25
Internal Diameter= 73.2mm
Outside Diameter= 76.2mm
Outside Temperature= 206°C
Inside Temperature= ?

I managed to get the inside temperature at the exhaust exit which gave me...

Inside Temperature= 171°C
Outside Temperature= 90°C

With that I was able to use the formula:

Heat Transfer = ((2 * pi * k * L)/(Ln(Outside Dia/Inside Dia)) * (Inside Temp - Outside Temp)

This gave me a heat transfer figure of 159,043.5W

Whether any of that helps me figure out the temperature further up the exhaust pipe I have no idea. Especially considering I don't know the internal temperature of the gas at that section of piping. Anyone got any ideas?

 

[Chestermiller]

It isn't clear whether the OP is trying to determine the inside temperature from measurement of the outside temperature (surface of the pipe or in the surroundings?) or whether he is trying to do it some other way. There are two values of the outside temperature given, and it is confusing why they are different.