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US 5,174,122 AGranted
Method and means of low temperature treatment of items and materials with cryogenic liquid
AssigneeApplied Cryogenics, Inc.
InventorJeffrey Levine
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AssigneeApplied Cryogenics, Inc.
InventorJeffrey Levine
Estimating the term…
A payload loaded into a chamber is cycled to a low temperature of about -320.degree. F. using liquid nitrogen fed to a heat exchanger evaporator that is located at the top of the chamber so that gaseous nitrogen vapor from the evaporator, at substantially the same temperature as the liquid nitrogen, is circulated to a payload in the chamber below, and, at the same time, gas from the chamber is circulated upward to highly thermally conductive fins on the heat exchanger that are cooled by the liquid nitrogen evaporation. Thus, heat from the payload is fed from the gas circulating upward to the heat exchanger to evaporate the liquid nitrogen and so the payload located at the bottom of the chamber is cooled by gas kinetics and is never touched by the liquid nitrogen. In a preferred embodiment, an electric heater element and a fan are provided between the heat exchanger and the chamber and the heater is controlled to modify temperature descent rate during a low temperature cycle and to heat the chamber up to about +300.degree. F. for a high temperature cycle; and the heat exchanger, heater and fan are all carried by a (power) head that fits over and partially into the top of the chamber. Thus, the chamber may be a vacuum (envelope) chamber with no penetrations of the vacuum envelope to accommodate any of the elements, detectors or actuators and no cryogenic liquid inlet tubes penetrate the chamber.
Apparatus for carrying out cryogenic temperature processing of a payload including items and/or materials, for example, to improve wear, abrasion, erosion or corrosion resistivity characteristics or, improve dimensional stability characteristics or improve mechinability or provide stress relief to said items and/or materials, comprising:
In apparatus for carrying out cryogenic temperature processing of a payload of items and/or materials, the improvement comprising:
The method of carrying out cryogenic temperature processing of a payload including items and/or materials to improve wear, abrasion, erosion or corrosion resistivity characteristics or, improve dimensional stability, or improve machinability, or provide stress relief to said items and/or materials, including the steps of:
Dependencies are inferred from the claim text.