He II Two Phase Flow in an Inclinable 22 m Long Line

Rousset, Bernard; Gauthier, A.; Jager, B.; Weelderen, R. van

doi:10.1007/978-1-4615-4215-5_7

Cited by 6 publications

(11 citation statements)

References 6 publications

(5 reference statements)

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“…In the framework of LHC cooling scheme studies, we have investigated the thermohydraulic behavior of He II two-phase flow [3,4]. The huge amount of data acquired on previous Cryoloop experiments confirmed the pressure loss predictions given by the Andristos/Hanratty [5] model.…”

Section: Introductionmentioning

confidence: 73%

“…Specific devices designed to characterize mist and annular flow were added, whereas heat transfer measurements were maintained and improved. The "Cryoloop II" (figure 1) has already been described previously [4] and mainly consists of an inlet box used to create the inlet quality, a 10 m inclinable straight line of dimensions 42x43 mm, and an outlet saturated bath where excess liquid is evaporated. During a run, total mass flow ( 1 m ) is kept constant using a fixed aperture for the J.…”

Section: Introductionmentioning

confidence: 99%

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HeII co-current two phase flow at high vapor velocities

Rousset¹,

Jager²,

Muoio³

et al. 2002

AIP Conference Proceedings

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In the framework of LHC studies, we have performed several experiments on He II co-current two-phase flow. It was found that for high vapor velocities, the heat exchange capacity between the He II flow and the pipe wall is significantly better than what can be accounted for by the liquid to wall interface of a stratified two-phase flow pattern. This seems to indicate a transition from a pure stratified two-phase flow into either a partially annular two-phase flow or a stratified two-phase flow including liquid droplets in the vapor flow or a combination of the two. In the last two cases, it is assumed that liquid droplets which get dispersed on the tube wall increase the wetted surface. A new facility has been designed to analyze this flow behavior. High sensitivity capacitive liquid level sensors glued onto the inner wall of the pipe were used in order to detect a possible semi-annular flow pattern whereas light diffraction and scattering were used to detect liquid droplets. Finally, in addition to a circumferential heat exchange box, local heat exchange boxes located at different azimuth positions are added. Description of this new facility, calibration of the local heat exchange boxes and first results are presented. ABSTRACTIn the framework of LHC studies, we have performed several experiments on He II co-current two-phase flow. It was found that for high vapor velocities, the heat exchange capacity between the He II flow and the pipe wall is significantly better than what can be accounted for by the liquid to wall interface of a stratified two-phase flow pattern. This seems to indicate a transition from a pure stratified two-phase flow into either a partially annular two-phase flow or a stratified two-phase flow including liquid droplets in the vapor flow or a combination of the two. In the last two cases, it is assumed that liquid droplets which get dispersed on the tube wall increase the wetted surface. A new facility has been designed to analyze this flow behavior. High sensitivity capacitive liquid level sensors [1] glued onto the inner wall of the pipe were used in order to detect a possible semi-annular flow pattern whereas light diffraction and scattering[2] were used to detect liquid droplets. Finally, in addition to a circumferential heat exchange box, local heat exchange boxes located at different azimuth positions are added. Description of this new facility, calibration of the local heat exchange boxes and first results are presented.

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

HeII co-current two phase flow at high vapor velocities

Rousset¹,

Jager²,

Muoio³

et al. 2002

AIP Conference Proceedings

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“…As already mentioned and explained [4], wall heat transfer is directly proportional to the inner wetted perimeter of the tube. Heat transfer is improved at high vapour velocities (figure 4).…”

Section: Results and Analysismentioning

confidence: 61%

Heat Transfer Enhancement of He II Co-current Two-phase Flow in The Presence of Atomisation

Rousset

Thibault²,

Perraud³

et al. 2005

Proceedings of the Twentieth International Cryogenic Engineering Conference (ICEC20)

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Previous experiments performed on HeII co-current two-phase flow at CEA Grenoble have shown the existence of a transition from stratified two-phase flow to droplet mist flow at high vapour velocities. The realisation of a new refrigerator/liquefier able to produce up to 20 g/s of single phase superfluid helium at 1.8 K (instead of 7 g/s previously) was achieved. Benefit was taken of the necessary junction between the existent test line and the refrigerator to introduce some new instrumentation [1]. Results of preliminary experiments performed on this new configuration are given. The response of liquid level and vapour density on droplet flow is presented. First results on pressure drop obtained for a total mass flow rate of 15 g/s are also presented. Finally, the use of various capacitive level gauges glued at different azimutal positions along the inner pipe give access to the perimeter wetted by a continuous thin liquid film.

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“…In the same way, from upstream to downstream, we measure the mass flow (Coriolis mass flowmeter), the power used to create the vapor flow, the temperature at both ends of the line and the corresponding differential pressure, the heat transfer through a heat exchange box [2] filled with 1 bar pressurized helium which is converted into an equivalent wetted perimeter (P), and the level of bulk liquid by means of parietal capacitive sensors azimuthally distributed [4]. Two visualization zones are also used to characterize the droplet flow (measurement of interfacial area, velocity and diameter of droplets [5]).…”

Section: Instrumentation Of the Test Linementioning

confidence: 99%

“…The purpose of the Cryoloop experiment [2] was to study the heat transfer capabilities provided by such a flow. We previously showed that, for vapor velocities exceeding typically 4 m/s, the heat transfer between the wall of the pipe and the HeII two-phase flow is improved with respect to a purely stratified situation [3].…”

Section: Introductionmentioning

confidence: 99%

Comparison between Normal and HeII Two-phase Flows at High Vapor Velocities

Perraud

Rousset

Thibault³

et al. 2006

AIP Conference Proceedings

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We present results on helium co-current two-phase flow experiments at high vapor velocity obtained with the use of the new CEA/SBT 400 W/1.8 K refrigerator [1]. For vapor velocities larger than typically 4 m/s, a mist of droplets develops from the bulk liquid interface accompanied by an increase in heat transfer at the wall. Experiments were conducted in a 10 m long, 40 mm I.D. straight pipe, both in helium II and in helium I to compare these two situations. The respective roles of vapor density, vapor velocity and liquid level on atomization were systematically investigated. Light scattering experiments were performed to measure sizes, velocities and interfacial areas of droplets in a complete cross section. In-house-made heat transfer sensors located in the mist allowed us to deduce an upper value of the extra cooling power of the dispersed phase. The practical interest of atomized flow for cooling large cryogenic facilities is discussed by considering the balance between increase in heat transfer and pressure drops it induces. COMPARISON BETWEEN NORMAL AND HEII TWO-PHASE FLOWS AT HIGH VAPOR VELOCITIES ABSTRACTWe present results on helium co-current two-phase flow experiments at high vapor velocity obtained with the use of the new CEA/SBT 400 W/1.8 K refrigerator [1]. For vapor velocities larger than typically 4 m/s, a mist of droplets develops from the bulk liquid interface accompanied by an increase in heat transfer at the wall. Experiments were conducted in a 10 m long, 40 mm I.D. straight pipe, both in helium II and in helium I to compare these two situations. The respective roles of vapor density, vapor velocity and liquid level on atomization were systematically investigated. Light scattering experiments were performed to measure sizes, velocities and interfacial areas of droplets in a complete cross section. In-house-made heat transfer sensors located in the mist allowed us to deduce an upper value of the extra cooling power of the dispersed phase. The practical interest of atomized flow for cooling large cryogenic facilities is discussed by considering the balance between increase in heat transfer and pressure drops it induces.

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He II Two Phase Flow in an Inclinable 22 m Long Line

Cited by 6 publications

References 6 publications

HeII co-current two phase flow at high vapor velocities

HeII co-current two phase flow at high vapor velocities

Heat Transfer Enhancement of He II Co-current Two-phase Flow in The Presence of Atomisation

Comparison between Normal and HeII Two-phase Flows at High Vapor Velocities

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