Model-based minimization algorithm of a supercritical helium loop consumption subject to operational constraints

Supercritical helium loops at 4.2 K are the baseline cooling strategy of tokamaks superconducting magnets (JT-60SA, ITER, DEMO, etc.). This loops work with cryogenic circulators that force a supercritical helium flow through the superconducting magnets in order that the temperature stay below the wo...

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Published in:IOP conference series. Materials Science and Engineering Vol. 278; no. 1; pp. 12116 - 12123
Main Authors: Bonne, F, Bonnay, P, Girard, A, Hoa, C, Lacroix, B, Coz, Q Le, Nicollet, S, Poncet, J-M, Zani, L
Format: Journal Article
Language:English
Published: Bristol IOP Publishing 01.12.2017
Subjects:
Algorithms
Consortia
Constraints
Energy consumption
Helium
Liquid helium
Nuclear power plants
Optimization
Power consumption
Superconducting magnets
Superconductivity
Supercritical flow
Tokamak devices
ISSN:1757-8981, 1757-899X
Online Access:Get full text
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Summary:Supercritical helium loops at 4.2 K are the baseline cooling strategy of tokamaks superconducting magnets (JT-60SA, ITER, DEMO, etc.). This loops work with cryogenic circulators that force a supercritical helium flow through the superconducting magnets in order that the temperature stay below the working range all along their length. This paper shows that a supercritical helium loop associated with a saturated liquid helium bath can satisfy temperature constraints in different ways (playing on bath temperature and on the supercritical flow), but that only one is optimal from an energy point of view (every Watt consumed at 4.2 K consumes at least 220 W of electrical power). To find the optimal operational conditions, an algorithm capable of minimizing an objective function (energy consumption at 5 bar, 5 K) subject to constraints has been written. This algorithm works with a supercritical loop model realized with the Simcryogenics [2] library. This article describes the model used and the results of constrained optimization. It will be possible to see that the changes in operating point on the temperature of the magnet (e.g. in case of a change in the plasma configuration) involves large changes on the cryodistribution optimal operating point. Recommendations will be made to ensure that the energetic consumption is kept as low as possible despite the changing operating point. This work is partially supported by EUROfusion Consortium through the Euratom Research and Training Program 20142018 under Grant 633053.
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ISSN:1757-8981
1757-899X
DOI:10.1088/1757-899X/278/1/012116