Cool - Warm - Hot - Whaaaat?

[properchopper]

Metal is more thermally conductive than wood, if you are somewhere hot and that ambient temperature is above blood temperature, the metal piece will feel warmer than the wood instead of cooler, you are just getting a more accurate feel for the temperature. Luckily I have no wooden motors, so it is not an issue for me.


Sound advice there Tony, and I love that odour meter, I didn't know such a thing existed, but I bet a burned ESC would read over 9000.

Paul,

You're correctly describing emissivity
which is "the measure of an object's ability to emit infrared energy. Emitted energy indicates the temperature of the object. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody). Most organic, painted, or oxidized surfaces have emissivity values close to 0.95." [from Raytec site]

Interestingly enough the Infrared temp sensor that Jay pointed out in in post #1 does have a setting to compensate for surface emissivity whilst my high buck temp guns don't.

[zooma]

Just my rule of thumb.

100-120 F is cool
120-135 is warm
135-145 is hot
145-155 is too hot
155+ is burnt

[Shooter]

Metal is more thermally conductive than wood, if you are somewhere hot and that ambient temperature is above blood temperature, the metal piece will feel warmer than the wood instead of cooler, you are just getting a more accurate feel for the temperature. Luckily I have no wooden motors, so it is not an issue for me.

Yep. Conductivity. I like to think of it like this..... the metal object is pulling the heat out of your hand quicker, hence it feels colder.

[kfxguy]

Metal is more thermally conductive than wood, if you are somewhere hot and that ambient temperature is above blood temperature, the metal piece will feel warmer than the wood instead of cooler, you are just getting a more accurate feel for the temperature. Luckily I have no wooden motors, so it is not an issue for me.


Sound advice there Tony, and I love that odour meter, I didn't know such a thing existed, but I bet a burned ESC would read over 9000.

Lmao!

[Keagan-Z06]

Gots to get me a temp gun now I presume.

[TheShaughnessy]

Ask a group of people to feel a 'piece of wood' and a 'piece of metal', both at room temperature. 90% of them will tell you the piece of metal is cooler. 20% will insist it is cooler even after you've measured the temperature.

question one on my lab last week was exactly as you ask lol. The lab had to do with the specific heat of different materials (metals in this case). But why does the piece of metal "feel" cooler? That was also on there. Thermal*!***!***!***!**namics as one professor affectionately calls it. It has taken a lot not to ask about the rate of water flow and if more flow is better or worse for cooling. I've devised a gedankenexperiment to answer the question, but haven't moved to the real world yet.

[Shooter]

I think that's where I got the idea.......from a heat transfer class! That cooling question is interesting.

[bob horowitz]

question one on my lab last week was exactly as you ask lol. The lab had to do with the specific heat of different materials (metals in this case). But why does the piece of metal "feel" cooler? That was also on there. Thermal*!***!***!***!**namics as one professor affectionately calls it. It has taken a lot not to ask about the rate of water flow and if more flow is better or worse for cooling. I've devised a gedankenexperiment to answer the question, but haven't moved to the real world yet.

I've always wondered about that. How does flow rate affect cooling rate. Do you need more dwell? time for more effective cooling. I have a number of machines in my shop that have heat exchangers, mostly water used to cool gases. I've always wondered, never did the research.
Bob

[Fluid]

I actually did the experiment - but the Internet experts "knew better" and refused to believe the results. I encourage others to test for themselves....but remember that experiment results are only as good as the experimental method used....garbage in, garbage out.


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[bob horowitz]

I actually did the experiment - but the Internet experts "knew better" and refused to believe the results. I encourage others to test for themselves....but remember that experiment results are only as good as the experimental method used....garbage in, garbage out.


.

Fluid,
So what were the results, and what were the parameters? I'm really curious.
Bob