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Topic: Converting to degC/Watt Question  (Read 683 times)

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Offline eehelp

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Converting to degC/Watt Question
« on: July 09, 2024, 11:12:30 PM »
Hello Chemistry Community,
I’m trying to prove the units in equation (3) of the attached application note. I’ve gotten as far as this but can’t figure out where the gm goes. Any insight would be greatly appreciated.
Thermal Conductivity= ℃/W

Offline Hunter2

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Re: Converting to degC/Watt Question
« Reply #1 on: July 10, 2024, 01:52:00 AM »
For what stands gm. The calculation  is correct. gm is already in K.
The unit in SI is W/(mK) means Watt devided by meter and Kelvin ( Temperatur). Could be gm also a length?

Offline eehelp

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Re: Converting to degC/Watt Question
« Reply #2 on: July 10, 2024, 02:23:15 AM »
For what stands gm. The calculation  is correct. gm is already in K.
The unit in SI is W/(mK) means Watt devided by meter and Kelvin ( Temperatur). Could be gm also a length?

I was thinking it was grams...???

Offline Hunter2

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Re: Converting to degC/Watt Question
« Reply #3 on: July 10, 2024, 02:48:32 AM »
But a thermal conductivity has nothing to do with a mass. If it has a value of 1 W/mK then it doesn't matter you have 1 g or 1 kg of it. The conductivity is the same. Its like electrical conductivity. It's only depending on length, thickness and type of material.

Offline eehelp

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Re: Converting to degC/Watt Question
« Reply #4 on: July 10, 2024, 02:54:10 AM »
But a thermal conductivity has nothing to do with a mass. If it has a value of 1 W/mK then it doesn't matter you have 1 g or 1 kg of it. The conductivity is the same. Its like electrical conductivity. It's only depending on length, thickness and type of material.

Perhaps an artifact or even an error in the app note?

Offline Borek

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Re: Converting to degC/Watt Question
« Reply #5 on: July 10, 2024, 03:14:36 AM »
"gm cal" probably means gram calorie (AKA small calorie, AKA 0.001 kcal), it is one of these things people introduce to make life more difficult.

Compare https://en.wikipedia.org/wiki/Calorie

Or scroll to the appropriate section here: https://msis.jsc.nasa.gov/volume2/Appx_e_units.htm

Please note: it is impossible to follow what you wrote. You use equal sign but it is not clear what it refers to, definitely not to the previous line.
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Offline Hunter2

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Re: Converting to degC/Watt Question
« Reply #6 on: July 10, 2024, 06:32:45 AM »
I think that's it. gm cal = 0.001 Kcal

Offline mjc123

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Re: Converting to degC/Watt Question
« Reply #7 on: July 10, 2024, 10:28:02 AM »
Also 1 W is not 1 cal/s, but 1 J/s. They have the same dimensions, if dimensions is what you are concerned about, but different numerical values.

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