The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 22, 1994
Filed:
Feb. 16, 1993
Roland L Roehrich, Pittsburgh, PA (US);
Herman H Viegas, Bloomington, MN (US);
Thermo King Corporation, Minneapolis, MN (US);
Abstract
A refrigeration system which controls the temperature of a conditioned space to a predetermined temperature range adjacent to a selected set point temperature SP via a cooling cycle which includes evaporation a cryogen, such as CO.sub.2 or N.sub.2, in a heat exchanger. In an apparatus embodiment, a controller determines a desired evaporation vapor pressure value EPX of the cryogen as a function of the selected set point temperature SP, and then controls the evaporation pressure EP in the heat exchanger means as a function of the determined desired evaporating vapor pressure value. The controller further determines a desired superheat value SHX of the cryogen exiting the heat exchanger means as a function of the selected set point temperature SP, and controls the mass flow rate of liquid cryogen evaporating in the heat exchanger as a function of the determined desired superheat value. A method embodiment includes the steps of providing a desired evaporation vapor pressure value EPX of the cryogen as a function of the selected set point temperature SP, controlling the evaporation pressure in the heat exchanger means as a function of the desired evaporation vapor pressure value, providing a desired superheat value SHX of the cryogen exiting the heat exchanger means as a function of the selected set point temperature SP, and controlling the mass flow rate of liquid cryogen from the cryogenic cooling means to the heat exchanger means as a function of the desired superheat value.