Thermodynamics? number crunching thermal conductivity

AI Thread Summary
The discussion focuses on calculating heat transfer from polyethylene (PE) pipe, specifically converting thermal conductivity from W/(m·C) to BTU/(hr·ft·F). The thermal conductivity of the PE pipe is approximately 0.46 W/(m·C), which converts to about 0.266 BTU/(hr·ft·F). To determine the heat load (Q) for 10 square feet of PE pipe with a temperature difference (dT) of 10°F, the formula Q = k/d * ΔT * A is suggested, where k is the thermal conductivity and d is the wall thickness. The wall thickness of 0.120 inches must be converted to feet for accurate calculations. The final calculation indicates that using the correct units leads to a heat transfer rate of approximately 2.22 BTU/hr per square foot per degree Fahrenheit.
fastline
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I am working on some basic calcs for heat transfer from polyethylene pipe. My numbers are not working out right so I need a little refresher.

The PE pipe would have a TC of about .46 W/(m.*C). to get to BTU/(hr.ft.*F), I mult by .5779 to get .266.

Assuming 10sf of PE pipe, and let's say a dT of 10*F, how do I arrive at my BTU/hr? Wall thickness of piping is .120" but I am told that does not matter. IIRC, the unit is actualy per sf PER ft so I might actually divide by my thickness which gets me closer at around 2.22 BTU/hr/sf*F of pipe?
 
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fastline said:
I am working on some basic calcs for heat transfer from polyethylene pipe. My numbers are not working out right so I need a little refresher.

The PE pipe would have a TC of about .46 W/(m.*C). to get to BTU/(hr.ft.*F), I mult by .5779 to get .266.

Assuming 10sf of PE pipe, and let's say a dT of 10*F, how do I arrive at my BTU/hr? Wall thickness of piping is .120" but I am told that does not matter. IIRC, the unit is actualy per sf PER ft so I might actually divide by my thickness which gets me closer at around 2.22 BTU/hr/sf*F of pipe?

The formula for the heat load Q (BTU/hr) is:
Q=\frac{k}{d}ΔTA
where d is the wall thickness.
 
I guess I am second guessing the units here. Would you mind applying the math to my above figures? Would this indeed be

k=.266
d=.120

k/d = 2.22BTU?
 
fastline said:
I guess I am second guessing the units here. Would you mind applying the math to my above figures? Would this indeed be

k=.266
d=.120

k/d = 2.22BTU?
You need to use d expressed in feet. How many inches are there in 1 ft?
 

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