tilopa
I need to find out the temperature change of air going through a chilled copper tube. The air will be traveling through 15 feet of tubing at a rate of 1 liter/second. The copper tube is chilled to 20 degrees F by a refrigeration unit and the air is 90 degrees F when it enters the tube. What will be the temperature of the air when it exits the tube?

How can I calculate this.
Robittybob1
I'll be surprised if that is able to be calculated! It is more like a trial and see situation. Measure the temperature of the air is my suggestion.
Mekigal
You need a mechanical engineer . One that specializes in coolants and refrigeration .

My buddy Morris could help you with that . He spent his life in industrial cooling systems . I built his log house up 9 mile rd and drainage . Yeah he could do the calcs for yeah.

I played his retreat office party . Me and the band ( rock band not the band with Mary . I am in 2 bands ) It was our first gig and they was 90% stoic engineers . Man alive they had a good time . One Guy drank a fifth of whiskey before passing out drunk in his tent with his wife . Yeah he had an extra good time and am sure he felt it the next day .

So I don't know if we even have engineers here ?
Sciforum has lots of engineers. If you don't get results here go there .

I can almost think it through . It is all about differential . I have done heat loss calculations before but that was long ago. Mainly for heat loss in housing . The acceptable protocols changed many times over the years . The first one I learned was the best cause it was directly related to out put of a furnaces b.t.u. Then the window size was accounted for also so you came up with the B.T.U. out put based on the size of windows and square footage of the house . We got a little more technical and started determining the volume of air latter days , but the protocol became more political and at one time and may even be now you didn't need a furnace as it was all about insulation values . You had to meet the envelope as a whole values . Like for example if a window was a certain size you could make up its low insulation value by substituting higher values else where like in a framed wall . Cracks are you biggest heat loss . If you got a hole in the envelope it sucks the *** out of things. Then if extremely tight boat like well you got to think about indoor quality .

There is simple calculations with enough information . If my mind was not preoccupy by fantasies of grandeur I could probably whip it good for you .

Anyway you might take a look at "heat exchangers" and such for the work has already been done . You got your differential so there you go . Call a manufacture and talk to there engineer technical support guy

Mekigal
Not to be miss interpreted. "Didn't need a furnace" definition as follows .
The furnace was not in the calculations . Yeah you need a furnace in the North West , but energy applied had nothing to do with meeting the heat/loss calculations. It is all about loss of heat and the source and size of any heat unit is presumed to exist like a magic sky monkey
keith*
QUOTE (tilopa+Aug 12 2012, 12:55 PM)
I need to find out the temperature change of air going through a chilled copper tube. The air will be traveling through 15 feet of tubing at a rate of 1 liter/second. The copper tube is chilled to 20 degrees F by a refrigeration unit and the air is 90 degrees F when it enters the tube. What will be the temperature of the air when it exits the tube?

How can I calculate this.

Solder (or clamp) tap valves at your desired temperature logging distances along the tubes length, removing samples of air to observe.
EX:

-0 ft (start reading): Air temp at 90 F

-7 1/2 ft (midpoint reading): ? F

-15 ft (end reading) : ? F

Important aspects that will likely vary the temperature in tube:

-Copper tube gauge thickness.
-Copper tube diameter ( I.D.** ?)

The air should move thru the tube fairly rapidly for a 1 cu. liter/second sized tubing
Calculate expected air density heat loss/ft. for known values, from charts on the internet (or from what others have recommended here).

Take temperature readings from sampling valves and see how close your predicted temperatures were.

Note: You may find a final drop in temperature as the air exits the tube, back into a larger space (quick expansion of gas causing expected temp drop).

**-inside dimension
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