Helium liquefaction

Fig. 12. Helium liquefaction process. A represents adsorber E, expander.

For laboratory production of LHe, other so-called Collins-type liquefiers have been built with one or two stages of GM cooling before the Joule-Thomson expansion (e.g. ref. [50]). The thermodynamic analysis of Collins helium liquefaction cycle can be found in ref. [51]. 

Dispersion forces. These are weak attractions caused by instantaneous fluctuation of the electron distribution in molecules and even atoms. They were first posed by Fritz London whose focus was on helium liquefaction. Such London forces fall off with the sixth power of the distance of separation. Any individual fluctuation creates a +/— local charge and that instantaneous dipole can interact with other such instantaneous dipoles nearby. The important... 

The phenomenon of superconductivity was discovered at the beginning of the twentieth century by the Dutch physicist H. Kamerlingh Onnes, during the first attempts to liquefy helium (which at atmospheric pressure boils at 4.2 K). After refining the technique of helium liquefaction, in 1911, Onnes attempted to measure the electrical resistance of metals at these extraordinary low temperatures, and realized that at 4 K the resistance of mercury, as well as that of other metals indicated in Figure 1, became too low to be measured. This change in electrical property became the indication of the new superconductive physical state. The temperature below which materials become superconducting is defined as the critical temperature, Tc. 

As an introduction to the main part of the paper, it is pertinent to mention this year as the anniversary of a few significant events in thermal physics. Let us note the centenary of the first helium liquefaction by Heike Kamerlingh Onnes at Leiden. In his plenary report at the 18 European conference on thermophysical properties Dr. Amo Laesecke called this event a breakthrough in research on thermophysical properties of substances and, among other problems, he related the studies into metastable states of substances to uncharted territories in thermophysics. In this connection our workshop seems to be well-timed. 

Technical Aspects of Large Scale Liquid Helium Liquefaction and Transportation (3) 125... 

Helium liquefaction (Heike KamerUngh Onnes) Kamerlingh Onnes produces liquid helium at a temperature of about 4 kelvins. He will also discover superconductivity in several materials cooled to liquid helium temperature. 

The work of Kapitza [7] and the exceptionally notable developments of Collins [8] had in common the utilization of expansion engines in combination with counterflow heat exchangers, and both were successful in liquefying helium. The Collins system was the first to use multiple engines operating at intermediate temperatures and thereby eliminate the need for any auxiliary refrigeration. This feature, combined with certain constructional advantages [9], has led to a wide acceptance of the Collins system for helium liquefaction. 

A. Latham Jr. and H. O. McMahon, "Low temperature research is aided by simplified helium liquefaction," Refrigerating Engineering (June, 1949). 

Fig. 4.10. Simplified equipment arrangement for the Simon helium-liquefaction system.

Fig. 4.11. Process path describing the Simon helium-liquefaction system on a temperature-entropy diagram.

Fig. 4.12. "Mister, could you chill my beer for me " Cartoon concerning Helium liquefaction at...

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