Thermal Analysis for ATLAS Detector
Calculations of Thermal Regime of ATLAS Facility
Tech Area / Field
- PHY-NGD/Fluid Mechanics and Gas Dynamics/Physics
8 Project completed
Senior Project Manager
Malakhov Yu I
State Unitary Enterprise STRELA, Russia, Chelyabinsk reg., Snezhinsk
- Lawrence Livermore National Laboratory, USA, CA, Livermore
Project summaryExperimental facility ATLAS being designed at CERN is supposed to have large overall dimensions (tens of meters). Equipment incorporated in ATLAS will experience different heat loads (tens of kilowatts of heat are dissipated in environment). Therefore, air will circulate in the cavern housing ATLAS facility and heat exchange with free convection will take place in the cavern. It is necessary to estimate the temperature regime expected in the experimental facility ATLAS : air temperature in the cavern, distribution of temperature over the surfaces of facility and inside it. In particular, it is important to evaluate temperature gradients along and across the tubes in the muon chambers. The large aluminum muon chambers will change their dimensions in response to the temperature changes of the environment. Changes in chamber configuration caused by non-uniform heating might distort coaxial systems “tube-wire” that is strongly undesirable during the physical experiment. Therefore measures are to be taken to prevent large temperature gradients on the muon chambers.
The objective of the project is to calculate free-convection heat exchange in the ATLAS facility cavern taking into account the latest data received from CERN on the heat loads (heat release in tile-calorimeter, on the surface of the muon chambers, in the electronic racks and heat discharge in the toroidal cryostats). The project will also include calculations to study how different parameters influence heat exchange (heat exchange inside the muon chambers; how blocking of the air circulation between the inner chambers influences heat exchange with free convection). Special attention will be given to the temperature study in the cross-section of the detector (2D geometry) located at 2 meters from the point where two beams collide.
It is supposed to run basic calculations using commercial code (CFX). The calculation results will be compared to those obtained with other codes: Star CD (calculations will be run by CERN experts); SINARA-2D code developed at RFNC-VNIITF  and the codes implementing the method of heat balance .
Thermal calculations performed under the project will facilitate better understanding of the thermal mode of ATLAS facility and help generate practical recommendations for manufacture and assembly of the facility equipment (first of all, the muon chambers).
SINАRА-2D code was developed to calculate some emergency processes in nuclear reactors. The code models the flow of multi-component compressible and almost incompressible medium including strength and elastic-plastic properties, linear and non-linear heat conduction, etc. SINARA-2D code employs implicit finite-difference schemes to solve differential equations describing physical processes. Numerical algorithms for solving heat conduction and gas dynamic equations are based on ROMB technique developed at RFNC-VNIITF for the large deformation problems [4-8].
Since SINARA-2D was initially developed to solve the problems of another class, it is supposed to modify its algorithms and modules in the interests of convection calculations. For this purpose it is supposed to benefit from the expertise of RFNC-VNIITF’s experts in the sophisticated 2D calculations and development of algorithms for solving the equations of heat conduction and hydrodynamics. To solve effectively the problems of convection heat and mass transfer, it is necessary to improve the preciseness of the scheme taking into account the convection flows of mass, momentum and energy at the grid movement with respect to the medium. Some efforts will be needed to adapt difference scheme to model almost incompressible medium in convection problems. Radiation heat exchange will be included if necessary.
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