Pre-cooling
We get the best efficiency transfer efficiencies when the transfers lines from the Liquifier to the magnet are sufficiently cold. There are We have tested two main modes (paths) to pre-cool the system: the slow pre-cooling and the fast - pre-cooling as well as a combination of these two modes which allows to reduce the slow pre-cooling time. During the slow pre-cooling we can estimate when the system is cold enough through the behavior of the Tank T temperature. The fast pre-cooling transfers efficiency transfer efficiencies are about 47-49% which does not allow to fill the magnet entirely using just one Liquifier although higher efficiencies of about 54% can be obtained with the fast pre-cool if the Liquifier pressure is reduced to 3.5 PSI at the expense of near 2 hours (~8L) where the Liquifier is not producing while reaching the set pressure. The slow pre-cooling has consistently given the higher transfer efficiencies between 56 and 58% but requires long pre-cooling times (~ 4 to 5 hours) with the potential benefit of a slow filling which is still under study. The reported efficiency values were obtained performing the magnet fill from the seam level all the way to the level probe spike.
Slow pre-cooling:
There could be the extra benefit of the slow filling.
1. Enable the Flow PID control of the Magnet Return Bypass at 65 slm.
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Proceed to fill the magnet anytime after the transfer lines are cold. The system is sufficiently cold once the Tank T temperature decreases after opening VJVT (about 5 hours). The figure below shows an example of the Tank T behavior during a slow pre-cooling.
Filling
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1. Open the MagRetBypass valve fully by pressing the "Full Open" button on "MagRetBypass_Main.vi" in CCP and wait until you can see it is fully open on the CCP panel. The magnet pressure will start decreasing. The FMR may spike momentarily.
2. After the FMR has stabilized, set the Liquifier A/B to "Manual + Idle", open SV501A/B (inlet valve), and set FC501A/B at 45 SLM. Ensure the outlet valve SVNA/B is closed and the cold heads of the Liquifier are off.
3. When the magnet level reaches 48%, open VPC, close VJVA/B, close VJVT.
4. Set the Liquifier A/B back to "Auto+ Liquefy".
5. Enable the Pressure PID auto control of the MagRetBypass valve at 0.9 psi.
Post-filling
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Monitor the Liquifier A/B pressure until the cold-head temperatures are below 5.5 K ensuring the Liquifier A/B pressure doesn't go above 9 psi:
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