Refrigeration – Processes – Condensing and evaporating
Reexamination Certificate
1998-09-25
2001-03-20
Wayner, William (Department: 3744)
Refrigeration
Processes
Condensing and evaporating
C062S333000, C165S104210
Reexamination Certificate
active
06202425
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to commercial refrigeration systems for enclosed refrigerated spaces which have walk-in freezers or other large chilled spaces and primary mechanical refrigeration equipment in remotely located machine areas for supplying coolant fluid to the evaporators in the chilled spaces, with an intermediate heat exchange system between the primary mechanical refrigeration equipment area and the chilled spaces to reduce the amount of coolant that is communicated to the evaporator in the chilled space.
BACKGROUND OF THE INVENTION
Modern supermarkets require a large amount of refrigeration for freezing and chilling the goods purchased by its customers. Typically, the freezers and coolers are located in random positions about the customer areas of the supermarket, in optimum locations for marketing purposes. In some instances, large closed refrigerated spaces and fixtures, including walk-in freezers or walk-in coolers are provided for butchers and other personnel of the supermarket, and occasionally for customers where large stocks of chilled items are maintained. While these larger closed refrigerated spaces are highly desirable, it is also desirable to use as little refrigerant coolant fluid as possible to chill these spaces. This is because the refrigerants must pass through an evaporator in the chilled space and there is a hazard that the refrigerant will leak into the atmosphere of the closed chilled space and be inhaled by customers, workers, and others. Refrigerants may replace oxygen in a closed space and result in oxygen deprivation, and possibly death by asphyxiation.
As a result of this hazard, federal and state regulations limit the amount of refrigerant that can be used to cool freezer rooms and other large closed refrigerated spaces which can be occupied by a person, either by an employee of the supermarket or by a customer. In most instances, the typical walk-in refrigerated space, etc. requires more refrigerant than is permitted by the federal and local regulations in order to adequately cool the space, particularly when people frequently move into and out of the chilled space. The result of this situation is that walk-in refrigerated spaces and other large closed refrigerated spaces that have frequent entry of people and therefore a large refrigeration load are not commonly available in typical supermarkets.
Thus, it can be seen that it would be desirable to have available to supermarkets and other businesses a large closed refrigerated space that can be adequately chilled for its intended purposes without requiring a volume of refrigerant fluid that is in excess of the standards set by federal and state regulatory bodies to directly communicate with the evaporator in the refrigerated space.
SUMMARY OF THE INVENTION
Briefly described, the present invention comprises a commercial refrigeration system for a large closed refrigerated room having a high refrigeration load that is to be used by supermarkets and other large refrigerated installations. The refrigeration system includes an intermediate heat exchange non-compression cascade refrigeration system that is connected between a refrigerated space and a conventional or “primary” refrigerant compressor system of the type typically located in the machine room of a large supermarket. The cascade refrigeration system utilizes a small amount of refrigerant fluid in a closed loop configuration that is in direct communication with the evaporator of the refrigerated space. The intermediate heat exchange system comprises a non-compression cascade refrigeration system, e.g. a refrigeration system which operates without the use of compressors, that typically does not require pumps or other mechanical means for moving the coolant fluid, but which relies upon gravity, its own internal pressures and changes of phase of the coolant fluid for movement through heat exchangers.
More specifically, the intermediate cascade refrigeration system includes a condenser that is matched in heat exchange relationship with an evaporator of the primary refrigeration compressor system for cooling the refrigerant fluid of the cascade system. An evaporator of the cascade refrigeration system is positioned in the refrigerated space. A liquid and vapor separator is positioned in the coolant delivery and return lines between the evaporator and the condenser of the cascade system. A first coolant delivery conduit extends from the cascade condenser to the separator for delivering coolant in liquid phase to the separator, and a second coolant delivery conduit extends between the separator and the cascade evaporator for delivering coolant in liquid phase to the evaporator. Likewise, a first coolant return conduit extends between the cascade evaporator and the separator for returning coolant in a gaseous and liquid state from the cascade evaporator to the separator, and a second coolant return conduit extends between the separator and the cascade condenser for returning the coolant in a gaseous state to the cascade condenser.
When in operation, the refrigerant fluid being returned from the cascade evaporator in the chilled space moves from the evaporator to the separator in both liquid and gaseous states. The coolant that is in liquid form falls to the bottom of the separator where it is returned to the cascade evaporator, while the coolant that is in vapor form rises from the separator and moves upwardly to the cascade condenser. The cascade condenser condenses the coolant from vapor form to liquid form, and the liquid coolant is delivered by the first delivery conduit back to the separator. The liquid in the separator is then moved by gravity downwardly through its second delivery conduit to the cascade evaporator in the chilled space. Fans are used to circulate air in the chilled space to transfer the heat between the cascade evaporator and the chilled space.
The cascade refrigeration system does not require a compressor to move its fluid between the cascade condenser and the cascade evaporator in the chilled space, which is believed to result in a reduction of a hazard of leakage of the coolant from the system. Also, the cascade system can be located in the immediate vicinity of the chilled space, typically above the chilled space so as to take advantage of gravity movement of the refrigerant. This close proximity of the cascade refrigeration system with the chilled space results in only a small amount of coolant fluid being required to pass through the closed circuit of the cascade refrigeration system.
Thus, it is an object of this invention to provide an improved refrigeration system for walk-in coolers and freezers of the type used in supermarkets, which uses only a small amount of refrigerant fluid in the refrigerated space and which would avoid leakage of large amounts of refrigerant fluid in the refrigerated space.
Other objects, features and advantages of this invention will become apparent upon reading the following specification.
REFERENCES:
patent: 2233414 (1941-03-01), Hubacker
patent: 2581044 (1952-01-01), Ratcliff
patent: 0195891 (1991-08-01), None
Arshansky Yakov
Hinde David K.
Papagna Anthony
Thomas Kayden Horstemeyer & Risley
Wayner William
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