New question in “Ask the Experts”: Design length of transition tubes
The question is: Are there any rules of thumb for the design length of transition tubes in order to prevent condensation at the room temperature end?
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Rules of thumb for the design length of transition tubes
Are there any rules of thumb for the design length of transition tubes in order to prevent condensation at the room temperature end? By “transition tube,” I mean some standard size (O.D. and wall thickness) type 304 stainless steel tube with either 4 K or 80 K at one end...
Cuprate superconductors defy convention
To engineers, it’s a tale as old as time: Electrical current is carried through materials by flowing electrons. But physicists at the University of Illinois and the University of Pennsylvania found that for copper-containing superconductors, known as cuprates, electrons are not enough to carry the current.
Assessment of the Storage of Crude Helium in Reserves in Europe or Elsewhere
The following paper entitled, “Assessment of the storage of crude helium in reserves in Europe or elsewhere,” by Ralph Scurlock and Richard Clarke, was presented at the Cryogenics Conference in Dresden in September 2012. The full text of the paper appears below; download the presentation slides.
The Future of Helium? A paper presented at the Cryogenics conference in Dresden
The following paper entitled, "The Future of Helium? A global agency to oversee production, storage, supply and use of helium gas and liquid," by Ralph Scurlock and Richard Clarke, was presented at the Cryogenics Conference in Dresden in September 2012. The full text of the paper appears below.
BNSF to test liquefied natural gas in road locomotives
BNSF will begin testing a small number of locomotives using liquefied natural gas (LNG) as an alternative fuel later this year, BNSF chairman and CEO Matthew K. Rose announced at the CERAWeek conference on March 6.
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Cold Compressors
A common way to provide cooling below the normal boiling point of helium (4.2K) is to reduce the pressure above the bath of liquid helium, thus also reducing the bath’s equilibrium saturation temperature. For example, to produce a 1.8K bath of liquid helium, the saturation pressure has to be reduced...
Kapitza Conductance
Kapitza conductance refers to the heat transfer between a solid surface and a fluid that covers that surface. Fundamentally, it describes the inherent difficulty in transferring energy from a solid to the fluid covering the solid surface. This phenomenon was first observed by P. L. Kapitza in 1941 while studying...
Thermosyphons
A thermosyphon (or thermosiphon) is a device that transfers heat via natural convection in a fluid. The natural convection is driven by gravity with the colder, denser fluid flowing downhill and the warmer, less dense fluid flowing back up. Thus, thermosyphons connect an object to be cooled with a reservoir...
Magnets
From “Superconductivity: Present and Future Applications” by the Coalition for the Commercial Application of Superconductors. Particle physics uses accelerators to recreate the conditions of the early universe in an attempt to piece together the complex puzzle of how we got to where we are today. These huge machines are used...
Energy Storage
From “Superconductivity: Present and Future Applications” by the Coalition for the Commercial Application of Superconductors. With power lines increasingly congested and prone to instability, strategic injection of brief bursts of real power can play a crucial role in maintaining grid reliability. Small-scale Superconducting Magnetic Energy Storage (SMES) systems, based on...
Astronomy
ASTRONOMY IN SPACE by Peter V. Mason, retired, Jet Propulsion Laboratory, and Visiting Associate, California Institute of Technology. Pmason@alumni.caltech.edu In thinking about the reasons to perform astronomy in space, we first consider the effect of the earth’s atmosphere. On a scale of decreasing energy, gamma rays, cosmic rays, X-rays and...
Cryocoolers
What is a Cryocooler? A mechanism that can extract heat from an object (cooler) and by doing so draw its temperature down below approximately 150 Kelvin (cryo). — (Courtesy Dr. Willy Gully) What is the difference between a Cryocooler and a Cryostat? A cryostat is any device designed to maintain...
An Issue of Pressure and Flow Rate in a Supply Tank
Please help solve this problem: A supply tank requires a vaporizer to generate sufficient pressure to pump stored fluid up into a vehicle or tank. The available head is limited as the tank level falls and it is important to minimize the system pressure drop to maintain the desired flow...
Using MLI on VJ Line Joints or Cryo Storage Tanks
When installing Multi Layer Insulation (MLI) blankets on VJ line joints or cryo storage tanks should they be wrapped and tied down tight or loose? These are usually pre-cut to size. Also should they have an access hole at the point of where the molecular sieve is installed to help...
Separated layers of ice over a pipe
I want to know that why there are different layers of ice over a pipe carrying a cryogenic fluid, each layer separated with clear marks / lines? What do these layers signify?