Refrigeration – Processes – Treating an article
Patent
1987-01-21
1988-05-03
Capossela, Ronald C.
Refrigeration
Processes
Treating an article
62374, F25D 1306
Patent
active
047411686
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a cooling process and tunnel and more particularly applies to the cooling of a succession of individual parts adapted for example to be fitted in other elements in the cold state.
It is known to cool parts for contracting them before they are fitted. As the use of a refrigerating unit does not permit the obtainment of temperatures lower than -60.degree. C., which is often insufficient, it has been proposed to dip the parts into a cryogenic liquid such as liquid nitrogen.
However, this process is expensive, as it consumes large quantities of liquid nitrogen, the refrigerating properties of which are not used in an optimum manner.
An object of the invention is to provide a cooling apparatus whereby it is possible to obtain a wide range of cooling temperatures with a reduced consumption of cryogenic liquid.
The invention therefore provides a cooling process comprising forming a column of material to be cooled in a tube which is open at its upper end; cooling this column by vaporization of a cryogenic liquid outside said tube and then injection of the resulting gas in the vicinity of the base of the column; causing said gas to flow upwardly in the tube; and progressively extracting the cooled material from the base of the tube by the effect of gravity.
The invention also provides a cooling tunnel for carrying out such a process. This tunnel comprises a tube having an upper opening for supplying material to be cooled and a lower opening for discharging the cooled material under the effect of gravity, and a heat exchanger coaxial with and located outside said tube, said exchanger comprising a conduit whose inlet end is connected to a source of cryogenic liquid and whose outlet end communicates through openings with the tube in the vicinity of its lower end.
An embodiment of the invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 is a vertical sectional view of a cooling tunnel according to the invention;
FIG. 2 is a similar view of the lower end of the tunnel, in another stage of its operation;
FIG. 3 is a cross-sectional view, taken on line III--III of FIG. 4, of another embodiment of the tunnel according to the invention, and
FIG. 4 is a longitudinal sectional view, taken on line IV--IV of FIG. 3, of the lower part of this tunnel.
The tunnel shown in FIG. 1 is adapted to cool a succession of rings A, for example valve guides, adapted to be fitted in the cold state in the cylinder heads of motor vehicle engines. This tunnel, which has a general shape of revolution about a vertical axis X--X, comprises a central tube 1 surrounded by a second tube 2, a heat exchanger 3 disposed around the tube 2, a device 4 for closing the lower end of the tube 1, and a thermal insulation 5 contained in an outer case 6.
The tube 1, which is adapted to surround the rings A with a notable clearance, is open at both ends; it defines with the tube 2 an intermediate annular chamber 7 closed at both ends by a suitable upper plug 8 and a suitable lower plug 9, the latter being composed of a thermally insulating material. The tube 1 has a ring arrangement of orifices 10 located slightly above the plug 9.
The heat exchanger 3 is disposed in the median region of the tube 2 and extends a part of the length of the latter. It consists of a rod 11 helically wound around the tube 2 and gripped between the latter and a fluidtight housing 12. The rod 11 thus defines in the housing 12 a helical passage 13 whose lower end is connected to a liquid nitrogen supply conduit 14 which is controlled by an electrovalve 15, while the upper end of the passage 13 communicates with the chamber 7 through a ring arrangement of orifices 16.
The insulation 5 may be constituted by an insulating material, for example a foam of plastics material, which fills the space defined by the housing 12, the upper and lower parts of the tube 2 and the case 6.
A temperature probe 17 extends through the case 6, the insulation 5 and the tube 2 and enters the chamber 7 at the level of the orifices 10. This
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Boyer Bernard
Giacinti Louis
Thonnelier Jean-Yves
Capossela Ronald C.
L'Air Liquide Societe Anonyme pour l'Etude et, l'Exploitation de
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