Cryogenic liquid cylinder perfomance 1

[ampis]

Back Ground:-
I am talking about cryogenic Liquid Cylinder.
The Cylinder is Super + vacuum Insulated.

Previously we were using 500 mm diameter outer vessel. But now they have changed it to 550 mm Diameter Outer vessel.
( Done to accomodate more layers of insulation)

Even after the increased layers of insulation the prefomence remains the same.

My point of view is that, since the outer dia of the vessel is increased we are using higher length of the copper tube. (For both pressure builder + vaporizer) there fore ubable to get the desired perfomance(1 meter approx). By cutting the length of the copper tube we can reduce conduction through copper and get a better perfomance.

But i am not getting enough support from my seniors. They are more focused towards the insulation efficiency. Eventhough we used same insulation material in both cases.

I have joined recently as product developer and do not know weather my case has any merit. Please provide your suggestions.

 

[iainuts]

Hi ampis,
Heat leak to the inner vessel is a function of 2 primary heat transfer modes, radiation heat transfer and conduction. Convection is virtually eliminated by the vacuum.

From my experience, the balance between the two is 'typically' and very roughly 50/50, or perhaps slightly higher heat leak due to thermal conductivity if anything. So you may be able to reduce the heat leak due to radiation very slightly by adding layers, but there really needs to be a lot of layers added to make a measurable difference.

In regards to the piping between the inner and outer vessels, these lines provide a heat leak path via thermal conductivity. Copper of course, is highly conductive compared to stainless steel and is more difficult to get a good seal, so copper is not typically used. Changing to stainless steel is one thing you could do to reduce heat leak. Also, maximizing the length of line is a second thing, so longer lengths of pipe between the inner and outer vessels can also help reduce heat leak.

 

[ampis]

Thank you iainuts,
I was also thinking in same line but doing exactly opposite exactly opposite. If you look at liquid cylinder, the copper is in contact with SS outer vessel. So instead of increasing length of pipe between inner and outer vessel i am concentrating on reducing the contact area of copper and outer vessel.

I hope both will end up providing the same kind of results.
I will be starting experiments pretty soon, any suggestions ???

I am attaching a picture for reference.

 

[EdStainless]

Don't use Cu at all, only use SS, and make the tubes longer and thinner if possible.

What is your insulation? Metalized plastic film? Have you looked at more layers of thinner film? Is it 'crinkled' to create many small contact points?

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