Cryogenic System for the Spallation Neutron Source

Arenius, D.; Chronis, W. C.; Creel, J.; Dixon, K.; Ganni, V.; Knudsen, P.

doi:10.1063/1.1774683

Cited by 10 publications

(6 citation statements)

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“…In 1994-95, the Floating Pressure Process was applied to all four major cryogenic plants at Jefferson Lab (JLab), which are manufactured by different vendors. Later it was applied to Michigan State University (MSU) [6], the Spallation Neutron Source (SNS) [7], Brookhaven National Laboratory (BNL) [8] and for NASA at the Johnson Space Center (JSC) [4]. In all cases, it has resulted in substantial improvements in the system's efficiency, capacity, reliability and stability.…”

Section: Applications To Datementioning

confidence: 99%

Optimal Design and Operation of Helium Refrigeration Systems Using the Ganni Cycle

Ganni¹,

Knudsen²,

Weisend³

2010

AIP Conference Proceedings

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The constant pressure ratio process, as implemented in the floating pressure -Ganni cycle, is a new variation to prior cryogenic refrigeration and liquefaction cycle designs that allows for optimal operation and design of helium refrigeration systems. This cycle is based upon the traditional equipment used for helium refrigeration system designs, i.e., constant volume displacement compression and critical flow expansion devices. It takes advantage of the fact that for a given load, the expander sets the compressor discharge pressure and the compressor sets its own suction pressure. This cycle not only provides an essentially constant system Carnot efficiency over a wide load range, but invalidates the traditional philosophy that the ('TS') design condition is the optimal operating condition for a given load using the as-built hardware. As such, the Floating Pressure-Ganni Cycle is a solution to reduce the energy consumption while increasing the reliability, flexibility and stability of these systems over a wide operating range and different operating modes and is applicable to most of the existing plants. This paper explains the basic theory behind this cycle operation and contrasts it to the traditional operational philosophies presently used.

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Section: Applications To Datementioning

confidence: 99%

Optimal Design and Operation of Helium Refrigeration Systems Using the Ganni Cycle

Ganni¹,

Knudsen²,

Weisend³

2010

AIP Conference Proceedings

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“…This was the first application of the Ganni Cycle floating pressure technology on a helium gas refrigeration system. Previous implementations of the floating pressure technology have been on 4K liquefaction and refrigeration systems [4,5,6], which have stored liquid helium level indications that can be used for varying the pressure levels (charge) in the system for capacity modulation.…”

Section: Floating Pressure Controlmentioning

confidence: 99%

Floating Pressure Conversion of Two 3.5 Kw, 20 K, Helium Refrigerators

Homan¹,

Ganni²,

Sidi‐Yekhlef³

et al. 2010

AIP Conference Proceedings

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Two helium refrigerators, each rated for 3.5KW at 20K, are used at NASA's Johnson Space Center (JSC) in Building No. 32 to provide cryogenic-pumping within two large thermal-vacuum chambers. These refrigerators were originally commissioned in 1996. New changes to the controls of these refrigerators were recently completed. This paper describes some of the control issues that necessitated the controls change-over. It will describe the modifications and the new process control which allows the refrigerators to take advantage of the Ganni Cycle "floating pressure" control technology. The controls philosophy change-over to the floating pressure control technology was the first application on a helium gas refrigeration system. Previous implementations of the floating pressure technology have been on 4K liquefaction and refrigeration systems, which have stored liquid helium volumes that have level indications used for varying the pressure levels (charge) in the system for capacity modulation. The upgrades have greatly improved the performance, stability, and efficiency of these two refrigerators. The upgrades have also given the operators more information and details about the operational status of the main components (compressors, expanders etc.) of the refrigerators at all operating conditions (i.e. at various loads in the vacuum chambers). The performance data of the two systems, pre and post upgrading are presented.

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“…As done during the commissioning in 2013 [2], test heaters were used to impose a shield load and the load from the cold compressors and allowed a precise load measurement. Testing of the cold compressor load did not require sub-atmospheric helium as used by others, and was quite similar to that used for commissioning at SNS [8]. Figure 2 shows the inverse coefficient of performance (COP; for the 4.5 K cold box system) and system exergetic efficiency vs. the equivalent 4.5 K refrigeration load.…”

Section: Figure 1 Simplified Process Flow Diagram Of Compressor Systemmentioning

confidence: 99%

Modifications to JLab 12 GeV Refrigerator and Wide Range Mix Mode Performance Testing Results

Knudsen

Ganni

Hasan

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Cryogenic System for the Spallation Neutron Source

Cited by 10 publications

References 0 publications

Optimal Design and Operation of Helium Refrigeration Systems Using the Ganni Cycle

Optimal Design and Operation of Helium Refrigeration Systems Using the Ganni Cycle

Floating Pressure Conversion of Two 3.5 Kw, 20 K, Helium Refrigerators

Modifications to JLab 12 GeV Refrigerator and Wide Range Mix Mode Performance Testing Results

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