Numerical analysis of cooldown and warmup for the Large Hadron Collider

Liu, L; Riddone, G.; Tavian, L.

doi:10.1016/s0011-2275(03)00091-2

Cited by 6 publications

(9 citation statements)

References 2 publications

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“…The cooldown operation of the eight LHC sectors from 300 K to 4.5 K has been simulated and analyzed numerically [1]. However, to model and analyze the final cooldown process including the filling operation at 4.5 K and the cooldown from 4.5 K to 1.9 K, a new mathematical model is required due to the two-phase flow and superfluid helium involved.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the final cooldown from 4.5 K to 1.9 K of the Large Hadron Collider

Riddone¹,

Liu

Tavian³

2005

Proceedings of the Twentieth International Cryogenic Engineering Conference (ICEC20)

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To simulate and analyze the final cooldown process of a LHC standard cell (106.9 m length) including the filling operation at 4.5 K and the cooldown from 4.5 K to 1.9 K, a mathematical model is proposed and validated by experimental data. In this model, the mass equations for liquid and vapor, the momentum equation for liquid and the general equation for mixed flow are taken into account for the different filling and cooldown phases. As a result of the simulation, the temperature profiles of the cold mass of the cell as well as the evolution of the helium void fractions, filling ratio and HeII position are obtained. The filling and cooldown times have also been estimated, and some characteristics of heat transfer of the HeII bayonet heat exchanger have been presented. To simulate and analyze the final cooldown process of a LHC standard cell (106.9 m length) including the filling operation at 4.5 K and the cooldown from 4.5 K to 1.9 K, a mathematical model is proposed and validated by experimental data. In this model, the mass equations for liquid and vapor, the momentum equation for liquid and the general equation for mixed flow are taken into account for the different filling and cooldown phases. As a result of the simulation, the temperature profiles of the cold mass of the cell as well as the evolution of the helium void fractions, filling ratio and HeII position are obtained. The filling and cooldown times have also been estimated, and some characteristics of heat transfer of the HeII bayonet heat exchanger have been presented.

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Section: Introductionmentioning

confidence: 99%

Numerical study of the final cooldown from 4.5 K to 1.9 K of the Large Hadron Collider

Riddone¹,

Liu

Tavian³

2005

Proceedings of the Twentieth International Cryogenic Engineering Conference (ICEC20)

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“…The last phase from 4.5 K to 1.9 K is carried out using the cooling capacity of the 1.8 K refrigeration unit. After about two months, the temperatures of all the magnets were below 2 K. Discrepancies between the measured, calculated and predicted generic cool-down evolutions [3] were observed and analyzed. The unexpected phenomenon of unbalanced cool-down between neighboring cells supplied in parallel has also been analyzed.…”

Section: Introductionmentioning

confidence: 95%

Cool-Down of the First Sector of the Large Hadron Collider: Comparison Between Mathematical Model and Measurements

Liu¹,

Riddone²,

Serio³

et al. 2008

AIP Conference Proceedings

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The first 3.3-km long LHC sector (sector 7-8) was cooled down for the first time from room temperature to below 2.0 K from January to March, 2007. In this paper, the measured cool-down evolution of the sector is presented and compared with the calculated results. The discrepancies between the measured and calculated data are analyzed. In addition, two unexpected phenomena, unbalanced cool-down between two neighboring cells supplied by one valve, and longer cool-down time with respect to the predicted generic cool-down are thoroughly and numerically analyzed. ABSTRACTThe first 3.3-km long LHC sector (sector 7-8) was cooled down for the first time from room temperature to below 2.0 K from January to March, 2007. In this paper, the measured cool-down evolution of the sector is presented and compared with the calculated results. The discrepancies between the measured and calculated data are analyzed. In addition, two unexpected phenomena, unbalanced cool-down between two neighboring cells supplied by one valve, and longer cool-down time with respect to the predicted generic cool-down are thoroughly and numerically analyzed.

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“…Studies on thermal transient modes of a LHC typical sector [3,4,5] have been carried out and continually improved since 1997. Having successfully applied the mathematical model to a typical sector of LHC (sector 8-1), we have then used the model to simulate the other seven LHC sectors.…”

Section: Introductionmentioning

confidence: 99%

Study of the Cooldown and Warmup for the Eight Sectors of the Large Hadron Collider

Liu

Riddone²,

Tavian

2004

AIP Conference Proceedings

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The LHC cryogenic system [1] is based on a five-point feed scheme with eight refrigerators serving the eight sectors of the LHC machine [2]. The paper presents the simplified flow scheme of the eight sectors and the mathematical methods including the program flowchart and the boundary conditions to simulate the cooldown and warmup of these sectors. The methods take into account the effect of the pressure drop across the valves as well as the pressure evolution in the different headers of the cryogenic distribution line. The simulated pressure and temperature profiles of headers of the LHC sector during the cooldown and warmup are given and the temperature evolutions of entire processes of cooldown and warmup are presented. As a conclusion, the functions of the input temperature for the normal and fast cooldown and warmup, the cooldown and warmup time of each sector and the distributions of mass flow rates in each sector are summarized. The results indicate that it is possible to cool down any of the LHC sector within 12.7 days in normal operation and 6.8 days in case of fast operation. ABSTRACTThe LHC cryogenic system [1] is based on a five-point feed scheme with eight refrigerators serving the eight sectors of the LHC machine [2]. The paper presents the simplified flow scheme of the eight sectors and the mathematical methods including the program flowchart and the boundary conditions to simulate the cooldown and warmup of these sectors. The methods take into account the effect of the pressure drop across the valves as well as the pressure evolution in the different headers of the cryogenic distribution line. The simulated pressure and temperature profiles of headers of the LHC sector during the cooldown and warmup are given and the temperature evolutions of entire processes of cooldown and warmup are presented. As a conclusion, the functions of the input temperature for the normal and fast cooldown and warmup, the cooldown and warmup time of each sector and the distributions of mass flow rates in each sector are summarized. The results indicate that it is possible to cool down any of the LHC sector within 12.7 days in normal operation and 6.8 days in case of fast operation.

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Numerical analysis of cooldown and warmup for the Large Hadron Collider

Cited by 6 publications

References 2 publications

Numerical study of the final cooldown from 4.5 K to 1.9 K of the Large Hadron Collider

Numerical study of the final cooldown from 4.5 K to 1.9 K of the Large Hadron Collider

Cool-Down of the First Sector of the Large Hadron Collider: Comparison Between Mathematical Model and Measurements

Study of the Cooldown and Warmup for the Eight Sectors of the Large Hadron Collider

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