An on-line acoustic fluorocarbon coolant mixture analyzer for the ATLAS silicon tracker

Bates,; Battistin,; Berry,; Bitadze,; Bonneau,; Bousson,; Boyd, Kenneth; Botelho-Direito,; DiGirolamo,; Doubek,; Egorov,; Godlewski,; Hallewell,; Katunin,; Mathieu, Renaud; McMahon,; Nagai,; Perez-Rodriguez,; Rozanov,; Vacek,; Vitek,

doi:10.1109/animma.2011.6172830

Cited by 3 publications

(9 citation statements)

References 5 publications

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“…As a precursor to the measurements in C 3 F 8 /C 2 F 6 mixtures, transducer inter-distance calibration was followed with measurements in pure C 3 F 8 and C 2 F 6 . The average difference between measured sound velocities and the predictions [15], [16], [17]) was less than 0.04 % in both pure fluids, and was a strong indicator of a correct transducer inter-distance calibration.…”

Section: Transducer Distance Calibration For Flowmetry and Gas Mixturmentioning

confidence: 92%

“…The expected geometric deficit from sound path arguments according to eq. (14) would be -66.6 %, meaning that the flow velocity measured in such an instrument would need to be multiplied by a geometrical correction factor, GCF, to find the axial flow velocity in the main tube, where (maintaining the sign convention of the expected geometric deficit) GCF is expressed in terms of GD as: (15) In the configuration of figure 14a, GCF = 3, while in the configuration of figure 14b GCF depends explicitly on the crossing angle and main tube diameter, as shown in column 5 of table 3. In the configuration of figure 14c, where the entire sound path is in the flowing vapour, GCF is unity.…”

Section: Angled Crossing Geometry For Analysis and In-line Flowmetry mentioning

confidence: 99%

“…The present software [15] for C 3 F 8 /C 2 F 6 mixture analysis uses a pre-loaded look-up table of NIST-REFPROP generated sound velocity with 0.25 % granularity in C 3 F 8 /C 2 F 6 molar mixture and covering the expected range temperature and pressures (16.2 26.1 °C, 800 1600 mbar abs with 0.3 °C & 50 mbar granularity). These conditions correspond to the superheated C 3 F 8 /C 2 F 6 binary gas mixture environment in the vapour return line where the final instrument will be installed -some tens of metres from the evaporative zone within the silicon tracker.…”

Section: Cada and Analysis Softwarementioning

confidence: 99%

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A combined ultrasonic flow meter and binary vapour mixture analyzer for the ATLAS silicon tracker

et al. 2013

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An upgrade to the ATLAS silicon tracker cooling control system may require a change from C 3 F 8 (octafluoro-propane) evaporative coolant to a blend containing 10-25 % of C 2 F 6 (hexafluoro-ethane). Such a change will reduce the evaporation temperature to assure thermal stability following radiation damage accumulated at full LHC luminosity.Central to this upgrade is a new ultrasonic instrument in which sound transit times are continuously measured in opposite directions in flowing gas at known temperature and pressure to deduce the C 3 F 8 /C 2 F 6 flow rate and mixture composition. The instrument and its Supervisory, Control and Data Acquisition (SCADA) software are described in this paper.Several geometries for the instrument are in use or under evaluation. An instrument with a 'pinched axial' geometry intended for analysis and measurement of moderate flow rates has demonstrated a mixture resolution of 3.10 -3 for C 3 F 8 /C 2 F 6 molar mixtures with ~20 %C 2 F 6 , and a flow resolution of 2 % of full scale for mass flows up to 30gs -1 . In mixtures of widelydiffering molecular weight (mw), higher mixture precision is possible: a sensitivity of < 5.10 -5 to leaks of C 3 F 8 into part of the ATLAS tracker nitrogen envelope (mw difference 160) has been seen.An instrument with an angled sound path geometry has been developed for use at high fluorocarbon mass flow rates of around 1.2 kgs -1 -corresponding to full flow in a new 60kW thermosiphon recirculator under construction for the ATLAS silicon. Extensive computational fluid dynamics studies were performed to determine the preferred geometry (the ultrasonic transducer spacing and placement together with the sound crossing angle with respect to the vapour flow direction). A prototype instrument with 45º crossing angle has demonstrated a flow resolution of 1.9 % of full scale for linear flow velocities up to 15 ms -1 .In addition a further variant of the instrument is under development to allow the detection and elimination of incondensable vapour accumulating in the condenser of a fluorocarbon recirculator.The combined flowmeter and binary gas analysis instrument has many potential applications, including the analysis of hydrocarbons, vapour mixtures for semi-conductor manufacture and anaesthetic gas mixtures.

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Section: Transducer Distance Calibration For Flowmetry and Gas Mixturmentioning

confidence: 92%

Section: Angled Crossing Geometry For Analysis and In-line Flowmetry mentioning

confidence: 99%

Section: Cada and Analysis Softwarementioning

confidence: 99%

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A combined ultrasonic flow meter and binary vapour mixture analyzer for the ATLAS silicon tracker

et al. 2013

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“…The data that is gathered can be used for various applications, e.g. in the future upgrade of the ATLAS silicon tracker, in which the currently-used evaporative coolant (C 3 F 8 ) [3] will be replaced by a C 3 F 8 /C 2 F 6 mixture to provide the silicon substrates with a better safety margin against thermal runaway [4]. For this purpose, it will be necessary to have detailed knowledge of the properties of the refrigerant mixture, which can be obtained with our measurements.…”

Section: Introductionmentioning

confidence: 99%

“…The measurement setup is based on a pair of ultrasonic gas analyzers [1,2] that are designed for realtime measurements of the speed of sound in the gas that is under analysis. The analyzer, shown in figure 1, is composed of three main parts; the analyzing chamber, the I/O modules, and the supervisory software.…”

Section: Introductionmentioning

confidence: 99%

An experimental setup with ultrasonic gas analyzers and real time analysis of the composition of a binary gas mixture

Vacek

Vítek

Doubek

2013

EPJ Web of Conferences

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Abstract. This paper describes an automated measuring apparatus with an ultrasonic gas analyzer and realtime analysis of the composition of the gas. The apparatus is designed for preparing binary gas mixtures and making measurements in a wide range of pressures (from 0.8 bar a to 15 bar a ) and temperatures (between -15°C and 80°C). The apparatus was developed to determine the thermophysical properties of fluorocarbon mixtures for potential use in the cooling circuits of several Large Hadron Collider projects at CERN. The design of its control system took into account the safety and reliability of the gas analyzer, and the need to limit the presence of laboratory personnel. The control system was implemented in PVSS-II, the Supervisory, Control and Data Acquisition standard chosen for LHC and its experiments at CERN. The second part of the paper describes the implementation and verification of the algorithm for continuous real-time determination of the composition of the refrigerant mixture. The algorithm is based on minimizing the quadratic norm from the measured data and from the pre-generated look-up tables acquired from the NIST REFPROP software package.

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A subgradient-based cutting plane method to calculate convex hull market prices

Wang

Luh

Gribik³

et al. 2009

2009 IEEE Power &Amp; Energy Society General Meeting

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The unit commitment and economic dispatch problem in electricity markets has mixed-integer variables with piecewise linear bids. By using Lagrangian relaxation, a concave and piecewise linear dual problem is obtained.The resulting multipliers can be used to set prices in the convex hull pricing model, and this would result in the minimal uplift payment. This paper presents a subgradient-based cutting plane method to obtain the optimal multipliers in a computationally efficient way. The idea is to use subgradients to find an approximate center of the feasible polyhedron within the cutting plane framework. The time consuming process of finding centers such as analytic centers can thus be reduced. At nondifferentiable points, the cuts resulting from approximate centers may oscillate, and this difficulty is overcome by choosing a proper linear combination of these oscillating subgradients. The analytic centers are inserted as needed as spacer steps to ensure algorithm convergence. Testing results demonstrate the effectiveness of the algorithm.

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An on-line acoustic fluorocarbon coolant mixture analyzer for the ATLAS silicon tracker

Cited by 3 publications

References 5 publications

A combined ultrasonic flow meter and binary vapour mixture analyzer for the ATLAS silicon tracker

A combined ultrasonic flow meter and binary vapour mixture analyzer for the ATLAS silicon tracker

An experimental setup with ultrasonic gas analyzers and real time analysis of the composition of a binary gas mixture

A subgradient-based cutting plane method to calculate convex hull market prices

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