A Vacuum Flask Thermodynamic Equation

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An advanced thermodynamic equation for a vacuum flask is sought to model the cooling temperature of a liquid over time, focusing on the cylindrical center region while ignoring heat loss from the cap and bottom. Key parameters needed include reflectivity, emissivity, gas pressure in the gap, and the specific heat of the flask walls. The discussion emphasizes the importance of accurate modeling for potential design improvements or academic projects. The requester has marked the thread as advanced, indicating a desire for a graduate-level analysis. Further clarification on the purpose of the modeling and the requester's background in mechanical engineering and thermodynamics is encouraged.
Petersenwill36
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Im trying to find an advanced thermodynamic equation for a vacuum flask.

I am looking for an equation to find the temperature of a liquid at time t as it cools down. Ignore the cap and bottom section; assume there is no heat loss in those areas. I'm just interested in the cylindrical center region. I need all parameters such as reflectivity, emmisivity, gas pressure in the gap and the specific heat/properties of the walls as well as any other relevant parameters. I assume the length L doesn't matter. Can't seem to find this online.

Thank you in advance.
 
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See "Dewar."
 
Petersenwill36 said:
Im trying to find an advanced thermodynamic equation for a vacuum flask.

I am looking for an equation to find the temperature of a liquid at time t as it cools down. Ignore the cap and bottom section; assume there is no heat loss in those areas. I'm just interested in the cylindrical center region. I need all parameters such as reflectivity, emmisivity, gas pressure in the gap and the specific heat/properties of the walls as well as any other relevant parameters. I assume the length L doesn't matter. Can't seem to find this online.

Thank you in advance.
Welcome to PF.

Can you say more about why you want to do this modeling? Are you wanting to design a better dewar structure, so you want to be able to model the structures as accurately as possible? Or is this maybe for a shoolwork project?

What is your background in ME and Thermo? You've marked this thread with an "A" Advanced prefix, which means that you want the discussion to be at the graduate school and PhD level.
 

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