Speaker
Description
Actively cooled shields are used primarily in the temperature range at or below 20 K (e.g. LH2 or LHe) so that the heat load to these low temperatures is as small as possible. This is due to the high energy required to generate such low temperatures and the relatively low latent heat of the corresponding cryogens. Liquid nitrogen (LN2) with a boiling temperature of 77 K at 1 bar is very often used because on the one hand it is very inexpensive and on the other hand it is available everywhere indefinitely.
Even with two-stage cryocoolers, where the first stage is used for a cooling shield, this one is preset to a temperature of approx. 80 K.
Here, the optimal actively cooled shield temperature is calculated depending on the number of super insulation layers between the cold wall and the shield, and between the shield and the warm wall with a view to minimal energy consumption. Depending on the number of layers, these optimal shield temperatures can be far apart. Therefore, the gradient of this function of energy expenditure over the shield temperature is also formed in order to describe the importance of setting this optimal actively cooled shield temperature.
Finally, the energy savings when using an actively cooled shield compared to without an actively cooled shield are also calculated. The results demonstrate the enormous energy savings when using actively cooled shields and also the energy savings when setting the optimal actively cooled shield temperature.
| Submitters Country | Germany |
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