System and method for vapor control in cryogenic freezers

Abstract

A cryogenic freezer with cryogenic vapor control is disclosed. The cryogenic freezer is characterized in that the vapor control system is adapted to control the speed of the transition fan which moves some of the cryogen from a first cryogenic freezer to a second freezer in response to differences between the temperature of the process room, operating temperature of the cryogenic freezer; and a temperature of the exhaust. By adjusting the transition fan speed in response to such temperature differences the vapor control system operates to limit the flow of air from the process room into the freezer and also limits cryogen vapor flow from the freezer to the process room.

Description

FIELD OF THE INVENTION[0001]The present invention relates to cryogenic refrigeration and freezing systems, and more particularly to a system and method for the control of freezer vapors within the cryogenic refrigeration and freezing systems.BACKGROUND OF THE INVENTION[0002]In many conventional cryogenic refrigeration or freezing systems, the system typically run the exhaust fans and transition fans at the same speed and usually at a speed that can handle peak cryogen usage. Running the exhaust fans and transition fans at the same speed may result in the exhaust system forcing cryogen vapors out of the refrigeration equipment before some of the refrigeration energy can be extracted. In addition, running the exhaust fans and transition fans at the same speed may also result in pulling excess fresh air into the freezer that needs to be refrigerated which, in turn may cause deposition of water vapor from the excess room air inside the freezer. Both of these problems, namely inefficient...

AI Technical Summary

Benefits of technology

The present invention is a cryogenic freezer system that includes a freezer compartment, a cryogen supply subsystem, an exhaust subsystem, a control subsystem, and temperature sensors. The control subsystem is responsible for controlling the cryogen and the transition fan based on the temperature differences between the process room, the freezer compartment, and the exhaust. The technical effect of this invention is to efficiently control the cryogenic freezer system to maintain the desired temperature for food preservation.

Problems solved by technology

Running the exhaust fans and transition fans at the same speed may result in the exhaust system forcing cryogen vapors out of the refrigeration equipment before some of the refrigeration energy can be extracted.

In addition, running the exhaust fans and transition fans at the same speed may also result in pulling excess fresh air into the freezer that needs to be refrigerated which, in turn may cause deposition of water vapor from the excess room air inside the freezer.

Both of these problems, namely inefficient cryogen usage as well as excess room air tend to increase costs of operating the cryogen refrigeration system.

For example, if the food-process room temperature were to vary, such process room temperature change would likely affect the exhaust temperature causing erroneous adjustments in fan speed leading to inefficiencies in freezer operation.

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