Sudden Vacuum Loss in Long Liquid Helium Cooled Tubes

Dhuley, Ram; Sciver, S.W. Van

doi:10.1109/tasc.2014.2367156

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…Elaborate details of the experimental setup and the experimental procedure are given in [6]. Figure 1 depicts the general characteristics of the experimental setup.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

Propagation of nitrogen gas in a liquid helium cooled vacuum tube following sudden vacuum loss – Part II: Analysis of the propagation speed

Dhuley

Sciver

2016

International Journal of Heat and Mass Transfer

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The propagation of near-atmospheric nitrogen gas entering a liquid helium (LHe) cooled vacuum tube following an accidental loss of vacuum will be strongly influenced by condensation of the gas on the tube wall. Our previous experimental study revealed that in presence of condensation, the propagation speed of the gas front decreases nearly exponentially as the front advances in the tube. In the present paper the exponential decrease is studied analytically. We reduce the analytical model of the front speed, using assumptions, to show its derivative in the direction of propagation to be proportional to the mass deposition rate near the front. The deposition rate is then calculated at discreet locations along the tube from the condensation heat transfer rate at these locations. We find the deposition rate to diminish nearly exponentially along the tube so that the spatial derivative of the speed will show the same effect. In this special case the front speed will also fall exponentially along the tube. Within the experimental and procedural uncertainty, the exponential decay coefficient of the mass deposition rate also agrees reasonably with the empirically determined exponential decay coefficient of the propagation speed.

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“…Elaborate details of the experimental setup and the experimental procedure are given in [6]. Figure 1 depicts the general characteristics of the experimental setup.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

Propagation of nitrogen gas in a liquid helium cooled vacuum tube following sudden vacuum loss – Part II: Analysis of the propagation speed

Dhuley

Sciver

2016

International Journal of Heat and Mass Transfer

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“…The installation techniques for the pressure probes and the thermometers to ensure their proper operation in the cryogenic environment have been elaborated in [7]. The pressure sensors are Kulite XCQ-092 probes with 0-100/150 kPa range of operation.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

“…In this paper we present experimental and analytical findings that elucidate the role of this heat and mass transfer in slowing the propagation of nitrogen gas (a substitute of air) in a LHe cooled channel. An experimental apparatus [7] has been devised to simulate a sudden loss of vacuum in a 4.2 K LHe cooled tube and to measure the resulting rise in temperature and pressure along the tube as the gas propagates. The influence of mass and heat transfer on the propagation is investigated experimentally.…”

Section: Introductionmentioning

confidence: 99%

Propagation of nitrogen gas in a liquid helium cooled vacuum tube following sudden vacuum loss – Part I: Experimental investigations and analytical modeling

Dhuley

Sciver

2016

International Journal of Heat and Mass Transfer

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This paper describes propagation of near atmospheric nitrogen gas that rushes into a liquid helium (LHe) cooled vacuum tube after the tube suddenly loses vacuum. The loss-of-vacuum scenario resembles accidental venting of atmospheric air to the beam-line of a superconducting particle accelerator and is investigated to understand how the in-flowing air will propagate in such geometry. In controlled experiments, we simulated loss of vacuum by rapidly venting a large reservoir of nitrogen gas (a substitute for air) to a vacuum tube immersed in a LHe bath at 4.2 K. The resulting rise in the tube pressure and temperature were measured by pressure probes and thermometers arranged along the tube length. The data show that the propagation of nitrogen gas in the LHe cooled vacuum tube is orders of magnitude slower than in the same tube at room temperature. Interestingly, the gas front speed in the LHe cooled tube also decreases along the tube. A gas propagation model developed by employing conservation of mass identifies mass transfer (gas condensation in the tube) as the principal cause of the slow propagation as well as of the front deceleration. Some limitations of this analytical model are discussed in the context of quantifying the propagation speed. The speed obtained from direct measurements is seen to decrease exponentially along the tube. This exponential decay form of the propagation speed well represents the data from experiments that have different mass flow rates of nitrogen gas flowing into the vacuum tube after venting.

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Principles of Cryostat Design

Weisend

2016

Cryostat Design

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Sudden Vacuum Loss in Long Liquid Helium Cooled Tubes

Cited by 6 publications

References 9 publications

Propagation of nitrogen gas in a liquid helium cooled vacuum tube following sudden vacuum loss – Part II: Analysis of the propagation speed

Propagation of nitrogen gas in a liquid helium cooled vacuum tube following sudden vacuum loss – Part II: Analysis of the propagation speed

Propagation of nitrogen gas in a liquid helium cooled vacuum tube following sudden vacuum loss – Part I: Experimental investigations and analytical modeling

Principles of Cryostat Design

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