Cryogenic Refrigeration System.

摘要

1,153,374. Refrigerators. AIR PRODUCTS & CHEMICALS Inc. 1 June, 1967 [3 June, 1966], No. 25251/67. Heading F4H. In a Joule Thomson cryostat, helium is passed in heat exchange relationship with a liquid nitrogen bath before liquefaction at a Joule Thomson liquefier, liquid nitrogen from the bath is passed in heat exchange relationship with helium from the liquefier, and a radiation shield surrounding the liquefier is in thermal contact with the nitrogen bath. As illustrated, helium is passed from a bottle 8 through an adsorber 13 to an adsorber coil 37 immersed in a liquid nitrogen bath 23. The helium then passes through a duct 62 (Figs. 1 and 2), filters 73 and adsorber 72, and a heat exchange coil 68 to a Joule Thomson orifice 71. The liquid helium reservoir so formed is in contact with a holder 46 for an article to be cooled. Helium evaporating from the reservoir passes in heat exchange relationship with heat exchanger 68, adsorber 72 and duct 62 to an exhaust duct 36. Ducts 48 and 49 connect a coil surrounding the liquid helium reservoir to the liquid nitrogen bath to establish a thermosyphonic flow of liquid nitrogen through the coil. An intermediate portion of the duct 62 is formed as a coil (Fig. 2) cooled by and surrounding a Joule Thomson arrangement operating with hydrogen as its working medium. The hydrogen is supplied from a bottle 7 through an adsorber 12 to anadsorber coil 36 immersed in the nitrogen bath. The hydrogen then passes through a duct 58, part of which is coiled, to a Joule Thomson orifice 67. Liquid hydrogen collects in a reservoir 61 and gas evaporating from the reservoir passes over part of the duct 58 and through a duct 57 to an exhaust duct 35. The hydrogen and helium supply and exhaust ducts 33-36 are in thermal contact in a coil 32 located in a vacuum space 31 surrounding the nitrogen bath. The vacuum space communicates with the interior of a removable casing 19 surrounding the Joule Thomson liquefier. A thermally conducting radiation shield 42 surrounds the Joule Thomson liquefiers inside the casing 19 and at its upper end contacts the base of the liquid nitrogen bath. The helium and hydrogen may be recirculated via connections 9 and 11.