How much energy is lost from an Vaccum Insulated Vessel? 2

[AimHigh09]

Hello,

How much energy is lost from a vacuum insulated vessel coated with silver inside?
Ambient temperature: 25C
Vessel Inside temperature: 65C

Pl correct me if am missing any important information here or if it is a non-sensical question.

Thank you
Aim High

 

[MintJulep]

All of it.

 

[MortenA]

@Aimhigh09, what ment julep is saying is that you need more info if you want to calculate either heat loss at initial conditions or a cooling curve. This would include vessel geometry , liquid in vessel etc.

 

[IRstuff]

Is it the vacuum space walls that are silvered?

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[AimHigh09]

@MintJulep. I got your point and it is true.

Let me phrase my question warily here.

To illustrate, I have a container(LxWxH) vacuum sealed and on one end it has a circular opening of radius Xmeters and fitted with a rubber cork. The container is filled with the material of mass m(grams), specific heat C (Joules/gram.C) and temperature T(~63) degree Celsius. Vacuum container placed in ambinet temperature conditions.

The container is silver coated on the inside.

So my question is, How can I calculate the time period it takes for the vacuum sealed Container to reach from T(~63) degree Celsius to ~25C temperature?

I do not know what are the factors that need to be accounted for to calculate the particular time period.
Pl bear with me and I am not a mechanical engineer, electronics engineer by profession. So maybe I am asking a trivial question here, but pl guide me in this regard.

Thanks
AimHigh

 

[IRstuff]

Your wording is still unclear, since a cork cannot possibly seal a vacuum; is this a dual-wall vacuum insulated vessel, ala Thermos bottle? If so, say so.

If so,
> how good is the vacuum?
> why is the silver on the inside and not inside the vacuum space?
> what material is the vessel?

If not,
> what material is the vessel?
> how thick is it?
> what other insulation is there?

In any case, this is not an easy calculation, the typical approach is to use best practices, along with some experience, and test the vessel afterwards.

Being an EE is no excuse for not knowing physics; I have a BSEE.

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[danschwind]

AimHigh09,

Could you share a drawing of the system? It's very hard to visualize what you are trying to accomplish.

Is the material inside the container a liquid or a solid? If it is a solid, is it in contact with the container walls? Is this container double-walled with vacuum in between the walls?

 

[EdStainless]

For Thermos style glass flasks and their metal counterparts that are commonly used to short term transport and storage of liquefied gases these vales are determined empirically and are available in reference literature. Everyone wants to know the boil off rate. For large storage vessels the manufactures publish curves.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[georgeverghese]

For high vacuum insulated vessels, heat transfer is mainly by radiation between surfaces. See detailed discussion on page 11-104 in Perry Chem Engg Handbook, 7th ed, and related expressions to get heat loss.

 

[LittleInch]

Just do some tests.

Fill it with your liquid, then measure temperature every say 5 mins and plot it.

Much easier and will plot the losses where the inner and outer skins meet which is very difficult to model.

Also an IR camera will show where the hot spots are.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[AimHigh09]

Thank you all for your responses.
I certainly take all your suggestions. and ask for more question after done with experimenting.