# Black bodies

1. Nov 15, 2009

### Carlo09

Ok please can someone help or at least point me in the right direction with this question please?

I have air flowing through a pipe which is heated to 477 degrees via burners on the outside. The pipe its self is heated to 550 degrees and there is a thermocouple inside the air flow. However, the thermocouple recieves heat via radiation from the pipe wall and assuming both the wall and thermocouple are black bodies with respect to thermal radiation. the convection heat transfer coefficient is 160 w/m2 k

I need to show that the air temp is actually 477 degrees when the thermocouple shows 508 degrees!?

Ok so i konw black bodies absorb all and/or emit all. Therefore using Eb=Boltzmans constant *T^4 I see that the wall is getting 26031.49 w/m2 of energy and then is emiting all of this also, correct? I know the convection coefficient is 160 as given above but I am not given an area to use so how can I do this?

Thank you so much to whoever can help me.

Edit* we also know that it takes 6.1kw of energy to heat the air from 25 = 477 degrees and the flowrate of the air is 100m^3/Hr

Last edited: Nov 15, 2009
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