Refrigeration system

Details Refrigeration system Refrigeration system

2000-08-23

2001-05-29

McDermott, Corrine (Department: 3744)

Refrigeration

Plural paired different function refrigeration producing...

Reexamination Certificate

active

06237358

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a refrigeration system and more particularly to a technique for continuation of refrigeration operation in the event that a heat source equipment stops in a two-stage cascade refrigerating cycle refrigeration system.
BACKGROUND ART
As disclosed in Japanese Unexamined Patent Gazette No. H09-210515, there is a conventional refrigeration system which is formed into a two-stage cascade refrigerating cycle of the vapor compression type by connecting together a high temperature-side refrigerant circuit and a low temperature-side refrigerant circuit through a refrigerant heat exchanger. More specifically, the high temperature-side refrigerant circuit, on the one hand, comprises a closed circuit formed by sequential connection, established by refrigerant piping, of a compressor, a heat source-side heat exchanger, an expansion valve, and an evaporation portion of a refrigerant heat exchanger. On the other hand, the low temperature-side refrigerant circuit comprises a closed circuit formed by sequential connection, established by refrigerant piping, of a compressor, a condensation portion of the refrigerant heat exchanger, an expansion valve, and an application-side heat exchanger.
Such a two-stage cascade refrigerating cycle refrigeration system finds applications in refrigerating apparatus such as showcases for foods or the like installed at stores (e.g., super markets and convenience stores). Defined in such a showcase are a display space for frozen foods in the showcase chamber and an air passage for the circulation of air with the display space. The application-side heat exchanger, which is disposed in the air passage, is able to provide a supply of air into the showcase chamber with the aid of an air blower.
During the operation of the showcase, refrigerants are circulated in the high temperature-side refrigerant circuit and in the low temperature-side refrigerant circuit, wherein heat exchange is carried out between the refrigerants of these two refrigerant circuits in the refrigerant heat exchanger. With regard to the low temperature-side refrigerant circuit, a refrigerant discharged out of the compressor condenses in the refrigerant heat exchanger, decompresses in the expansion valve, and thereafter evaporates by heat exchange with air flowing through the air passage in the application-side heat exchanger in the showcase, whereby the air is cooled. Then, the cooled air is supplied, through the air passage, into the display space in the showcase chamber. In this way, foods are preserved at a predefined low temperature to maintain their freshness.
However, in such a conventional showcase constructed in the way described above, the operation will be brought into a stop when there occurs a failure in some equipment on the heat source side (e.g., the compressor), even though the application-side equipments are normally operating. There are some possible means of coping with such stoppage, one of which is to transfer the goods to another showcase that remains in operation. This, however, results in an increase in the load of refrigerating/cooling, therefore producing the problem of making it impossible to maintain the quality of goods at a satisfactory level. Particularly, in the case a freezing showcase stops, this produces the problem that the stored goods cannot be preserved at a satisfactory level of quality even when transferred into a cold storage showcase.
Bearing in mind the above-described problems, the present invention was made. Accordingly, an object of the present invention is to maintain the quality of goods by achieving continuation of refrigeration operation even when a heat source-side equipment stops in a two-stage cascade refrigerating cycle refrigeration system applied to a showcase or the like.
DISCLOSURE OF INVENTION
In accordance with the present invention, even when in a two-stage cascade refrigerating cycle refrigeration system an equipment on the heat source side stops, a high temperature-side refrigerant circuit will be formed by making utilization of a refrigeration circuit provided in air conditioning apparatus or the like, for the achievement of continuation of two-stage cascade refrigerating cycle operation.
More specifically, the present invention provides first solving means comprising a first refrigeration circuit (
1
) for a refrigerating apparatus (
6
) which is formed into a two-stage cascade refrigerating cycle by establishing connection between a high temperature-side refrigerant circuit (
3
) and a low temperature-side refrigerant circuit (
4
) through a first refrigerant heat exchanger (
5
A), a second refrigeration circuit (
2
) which is formed into a refrigerating cycle different from that of the first refrigeration circuit (
1
), and a second refrigerant heat exchanger (
5
B) connected to the low temperature-side refrigerant circuit (
4
), wherein the second refrigerant heat exchanger (
5
B) is connected, through connection piping lines (
41
,
42
), to a liquid piping line (
36
a
) and a suction-side gas piping line (
36
b
) of the second refrigeration circuit (
2
) and wherein first switching means (
43
,
44
) are provided for selective circulation of a refrigerant of the second refrigeration circuit (
2
) to the second refrigerant heat exchanger (
5
B) through the connection piping lines (
41
,
42
).
Further, the present invention provides second solving means according to the first solving means, wherein the second refrigerant heat exchanger (
5
B) has a condensation portion (
21
B) connected serially to a downstream side of a condensation portion (
21
A) of the first refrigerant heat exchanger (
5
A), wherein the low temperature-side refrigerant circuit (
4
) has a bypass passage (
26
) so that refrigerant bypasses the second refrigerant heat exchanger (
5
B) to flow from the first refrigerant heat exchanger (
5
A) into an application-side heat exchanger (
24
), and wherein the low temperature-side refrigerant circuit (
4
) has second switching means (
27
,
28
) for switching between a first mode in which refrigerant passes through the bypass passage (
26
) to circulate in the condensation portion (
21
A) of the first refrigerant heat exchanger (
5
A) and the application-side heat exchanger (
24
) and a second mode in which the refrigerant circulates in the condensation portions (
21
A,
21
B) of both of the refrigerant heat exchangers (
5
A,
5
B) and the application-side heat exchanger (
24
).
The present invention provides third solving means according to the first solving means, wherein the second refrigeration circuit (
2
) is a refrigeration circuit for air conditioning apparatus.
The present invention provides fourth solving means according to the first solving means, wherein the first refrigerant heat exchanger (
5
A) is able to provide a supply of air to the chamber inside of the refrigerating apparatus (
6
) by means of an air blower. The present invention provides fifth solving means according to the first or fourth solving means, wherein the second refrigerant heat exchanger (
5
B) is able to provide a supply of air to the chamber inside of the refrigerating apparatus (
6
) by means of an air blower.
The present invention provides sixth solving means according to the first solving means, wherein the second refrigeration circuit (
2
) is formed into a single-stage refrigerating cycle.
In the first solving means, during normal operation, the chamber inside of refrigerating apparatus such as the freezing showcase (
6
) is maintained at a predetermined low temperature by two-stage cascade refrigerating cycle running operations by the first refrigerant heat exchanger (
5
A) in the first refrigeration circuit (
1
). On the other hand, when the heat source equipment (
11
) employed in the high temperature-side refrigerant circuit (
3
) of the first refrigeration circuit (
1
) stops operating due to failure or the like, it is possible to flow a refrigerant of the second refrigeration circuit (
2
) which is formed into, for example, a single-stage refrigerating cycle into the seco

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