Confused about thermal conductivity units

[JG MechEng]

I am setting up a steady state thermal analysis of a model. I am using FEPipe and the help file says this...

"For steady state or transient the thermal conductivity is a required input. If this value is
omitted, (as it often is), the user will get unpredictable thermal solutions. The standard units
are Btu/sec/in/deg.F for Imperial units....

ASME as well as all other books and documents I have report the thermal conductivity as BTU/(sec*in*degF). Are these units interchangeable? I feel like if I assign the constant (in this case 15.46) to the BTU term, because all the other values represent a single unit (1)...the units should be interchangeable (15.46 BTU/1sec/1in/1degF). I feel like an idiot not being able to work through this...but I'm stuck on it

 

[IRstuff]

Huh? 15 watts = 15 volts*amps for example.

I'm struggling to see what you are having problems with.

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[JG MechEng]

I think you are having trouble seeing my issue because it is most likely EXTREMELY TRIVIAL...I cannot find any evidence that supports the units of thermal conductivity to be Btu/sec/in/deg.F as the software documentation states except for this one site (

https://www.unitconverters.net/thermal-conductivity-converter.html

). All other documentation report the units as BTU/(sec*in*degF) or BTU*in/(sec*in^2*degF).

If the software documentation is correct, how do I get from BTU/(sec*in*degF) to Btu/sec/in/degF? I have been trying to walk through dimensional analysis and I cant get the units to work out...this is why I think they are the same unit, just written out in a different way

 

[IRstuff]

What "evidence" do you need besides Algebra 1?

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[Compositepro]

What often causes confusion is that thermal conductivity includes surface area and thickness terms. These factors are completely different physical quantities but usually the units are cancelled out. in/in2 = 1/in.

 

[JG MechEng]

@IRstuff - thanks for writing it out...I was making it more complex than.

 

[LittleInch]

FEpipe has just written the same thing in an a non scientific manner. Both of them are still BTU per second per inch per deg F. So you then multiply the number you have by time, thickness of material and temperature difference from one side to the other to get how many BTU are transferred from one side to the other in a given amount of time.

I've also seen it as BTU s^-1 in^-1 F^-1

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