Propane pressure gauge

[smokey73]

well you almost got it right.
U= is Over All Heat Transfer Coefficient
Jim...

I was using a simplification as noted and you are correct, it is the overall heat transfer coefficient. In my equation, instead of "thermal conductivity" I should have said "heat transfer coefficient most closely associated with the thermal conductivity of the metal of the tank surface and the liquid or gas in contact with the metal." For this particular situation, the dominant form of heat transfer is "conduction" in the short term. While there may be some convection if the wind is blowing while you are trying to do this. Plus, as the heat is transferred to the liquid, there would be some latent heat of vaporization as the heat is absorbed further cooling the liquid. For the short term though, those are second order effects and dominated by thermal conductivity.

 

[Ralph Johnstone]

I always serve my chicken soup very hot because then it is expanded and thus there is more soup in the bowl compared to when it is only lukewarm.

That only comes from the marketing department. They want it served hot because the poor schmuck that's slurping it thinks he's getting more soup. He still gets the same mass of soup.

 

[Ralph Johnstone]

Chicken soup may produce Methane in Ralph.

Compress the methane and feed it back into the propane bottle and you've got a renewable source of energy.

 

[jssailem]

Would they MIX or would they Layer?

 

[Ralph Johnstone]

Plus, as the heat is transferred to the liquid, there would be some latent heat of vaporization as the heat is absorbed further cooling the liquid

The absorbed heat would go towards increasing the temperature of the liquid, which would in turn increase the vapour pressure of the liquid. This would increase the overall pressure in the cylinder. However, there would be no cooling of the liquid as the boiling could only occur at an increased temperature due to the higher pressure.

Something like this:

 

[JamesG161]

In my equation, instead of "thermal conductivity" I should have said "heat transfer coefficient most closely associated with the thermal conductivity of the metal of the tank

As would a Nuclear Engineer from the USNA top award winner.
But remember the Steam side too.
Jim

 

[Ralph Johnstone]

Would they MIX or would they Layer?

From the point of density, methane would sit on top. Any diffusion would depend on temp. and press.

 

[Ralph Johnstone]

But remember the Steam side too.

Hot, hot !

 

[JamesG161]

However, there would be no cooling of the liquid as the boiling could only occur at an increased temperature due to the higher pressure.

Finally Ralph has it...

Now here is the key issue.
Both Stable Temperatures must be about the same or you have to use a correction calculation.

This is called Vapor/Liquid Equilibrium or when finally you reach a Steady Enthalpy Input.

 

[Ralph Johnstone]

Finally

Why do you say finally ? I had it all the time .

 

[jssailem]

I had it all the time.

Was it contagious?

 

[JamesG161]

Ask @jssailem about Enthalpy as he learned about Hurricane intensification.
He will splain it slowly to you Ralphy.
Jim...

 

[Ralph Johnstone]

This is called Vapor/Liquid Equilibrium

Seems like steam tables:

.............. but using using propane as the liquid.

Still doesn't apply to mass .

 

[Ralph Johnstone]

Was it contagious?

Yes. That's why I'm still here in isolation. No symptoms but test positive. Now they call me Typhoid Harry.

 

[Richard19068]

Compress the methane and feed it back into the propane bottle and you've got a renewable source of energy.

That would work if you used CNG instead of propane but the compression part might be difficult.

 

[Richard19068]

That only comes from the marketing department. They want it served hot because the poor schmuck that's slurping it thinks he's getting more soup. He still gets the same mass of soup.

Ralph, I hope you realize my comment was tongue in cheek.

 

[JamesG161]

Seems like steam tables:

For Weather, this

There is one for Propane too.

Jim...

 

[Ralph Johnstone]

Ralph, I hope you realize my comment was tongue in cheek.

Not gonna be tongue in cheek after you burn your cheek on that extra hot soup, let me tell you.

 

[FastOlson]

Duck tape still works

That's the right product if your duck is coming apart. OTOH, If you need to repair your monkey, you need some gorilla glue.

 

[smokey73]

Plus, as the heat is transferred to the liquid, there would be some latent heat of vaporization as the heat is absorbed further cooling the liquid.

I stand corrected. Should have said "latent heat of vaporization as the heat is absorbed, further cooling the surface of the tank (not the liquid in the tank)." You are absolutely correct as the vaporization process results in no increase in bulk temperature of the liquid but rather an increase in gas pressure, albeit very small for the values in this case (second order effects excluded).

My qualification sign off on the "pressurizer system" on a S5W/S3G Core 3 submarine nuclear power plant would have pulled his signature from my card. In fact, the 1st Class Petty Officer signing off my qual card at prototype corrected me on this too before he signed off on my card. The principle involved here is exactly the one that led to the misconception of the status of the liquid level in the pressurizer at Three Mile Island that then precipitated in manually securing High Pressure Coolant Injection that ultimately led to shifting the bubble from the pressurizer to the core and resulted in melting 1/3 of the core at Three Mile Island.

Not withstanding that, you should be able to tell a noticeable difference in the temperature of the tank above and below the liquid level line even with your hand, let a lone an IR Gun.