JPH11173711A - Dual refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To complete the defrosting at a high defrosting power of a coolant for a short time, without using electric heaters. SOLUTION: The refrigerator having a high- and low-temp. side refrigeration cycles A, B. The high-temp. side refrigeration unit A is constituted to be capable f a reverse cycle operation. A defrosting bypass circuit 18 is provided for bypassing a gas coolant x from a prim. refrigerator compressor 5 to the downstream of a prim. coolant pressure reducing mechanism 7 via a sec. refrigerant evaporator 12 in the reverse cycle operation. In the defrosting operation, the hot gas refrigerator x from the compressor 5 is fed to the evaporator 12 via are bypass circuit 18 to melt the frost on the evaporator 12, then evaporated by a sec. refrigerator condenser 6 acting as an evaporator and returned to the compressor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binary refrigeration system used as a refrigeration system for a showcase, and more particularly, to a defrosting mechanism in a binary refrigeration system.

[0002]

2. Description of the Prior Art For example, as a showcase refrigerating apparatus, as shown in FIG. 5, a primary refrigerant compressor 5 for compressing a primary refrigerant x, a primary refrigerant condenser 6 for condensing and liquefying the primary refrigerant x, a primary refrigerant a high-temperature side refrigeration unit in which a primary refrigerant decompression mechanism 7 for decompressing x and a primary refrigerant evaporator 8 for evaporating and evaporating the primary refrigerant x are sequentially connected via refrigerant pipes; A secondary refrigerant compressor 9, a secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, a secondary refrigerant decompression mechanism 11 for decompressing the secondary refrigerant y, and In some cases, a binary refrigeration apparatus including a low-temperature refrigeration unit in which a secondary refrigerant evaporator 12 for evaporating and evaporating the secondary refrigerant y is sequentially connected via a refrigerant pipe is used. Reference numeral 13 denotes a condenser 6 for a primary refrigerant.
Is a cooling fan for cooling. The primary refrigerant compressor 5 and the primary refrigerant condenser 6 constitute the outdoor unit 1, and the primary refrigerant decompression mechanism 7, the primary refrigerant evaporator 8, the secondary refrigerant compressor 9, and the secondary refrigerant Condenser 1
Numeral 0 constitutes the cascade unit 2, and the secondary refrigerant decompression mechanism 11 and the secondary refrigerant evaporator 12 constitute the showcase refrigeration unit 3, and the cascade unit 2 and the showcase refrigeration unit 3 is installed in the showcase arrangement room 4.

In the binary refrigeration system having the above structure, if the refrigeration operation is continued, frost formation proceeds on the evaporator 12 for the secondary refrigerant in the refrigeration unit 3 for the showcase, and the refrigeration capacity decreases. It is necessary to perform a defrosting operation at a predetermined time interval or by detecting the degree of progress of frost formation to melt and remove frost formation on the secondary refrigerant evaporator 12.

In a conventional defrosting operation, as shown in FIG. 5, a high-temperature discharge gas refrigerant (ie, hot gas) y discharged from a secondary refrigerant compressor 9 is supplied to a secondary refrigerant through a three-way valve 15. Circuit 1 for bypassing to the inlet side of evaporator 12
The hot gas y is supplied to the secondary refrigerant evaporator 12 through the bypass circuit 14 by switching the three-way valve 15 so that the compressor 9 for the secondary refrigerant communicates with the bypass circuit 14. However, the hot gas bypass method is used to melt and remove frost by the heat of the hot gas y.

[0005]

However, in the above-described hot gas bypass type defrosting operation, there is a problem that the defrosting time becomes long because the defrosting ability is limited. If a heat exchanger with a small fin pitch is used, such as a normal air conditioner evaporator, if defrosting is performed with a high defrosting capacity, only the area around the heat transfer tubes will melt first, and the Since there is a possibility that the entire frost will not melt, it is desirable to defrost slowly with a not so high defrosting capacity as in the hot gas bypass method. Since a heat exchanger having a relatively large heat transfer rate is used, even if defrosting is performed in a short time with a high defrosting ability, frost formation is caused only by the frost around the heat transfer tube. In addition, in the case of a showcase, since foods and the like are displayed, there is a demand that a shorter defrosting time is desirable.

There is also a method of removing frost on the secondary refrigerant evaporator by heating with an electric heater to remove the frost. However, the electric heater consumes a large amount of electric power, so that running costs are increased and periodic maintenance is performed. Is required.

[0007] The present invention has been made in view of the above points, and an object of the present invention is to make it possible to complete defrosting in a short time with a high defrosting capacity of a refrigerant without using an electric heater. Is what you do.

[0008]

According to a first basic configuration of the present invention (invention of claim 1), as means for solving the above-mentioned problems, a primary refrigerant compressor 5 for compressing a primary refrigerant x, a primary refrigerant The refrigerant pipe 1 includes a primary refrigerant condenser 6 for condensing and liquefying the refrigerant x, a primary refrigerant decompression mechanism 7 for decompressing the primary refrigerant x, and a primary refrigerant evaporator 8 for evaporating the primary refrigerant x.
6, a high-temperature refrigeration cycle A sequentially connected through
A secondary refrigerant compressor 9 for compressing the secondary refrigerant y, a secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, and depressurizing the secondary refrigerant y. In a binary refrigeration apparatus including a low-temperature side refrigeration cycle B in which a secondary refrigerant decompression mechanism 11 and a secondary refrigerant evaporator 12 for evaporating and evaporating the secondary refrigerant y are sequentially connected via a refrigerant pipe 17, The high-temperature side refrigeration unit A is configured to be capable of reverse cycle operation, and the gas refrigerant x discharged from the primary refrigerant compressor 5 during the reverse cycle operation of the high-temperature side refrigeration cycle A is vaporized for the secondary refrigerant. A defrost bypass circuit 18 is provided for bypassing to the downstream side of the primary refrigerant pressure reducing mechanism 7 through the device 12.

With the above configuration, during the defrosting operation, the high-temperature gas refrigerant (ie, hot gas) x discharged from the primary refrigerant compressor 5 passes through the defrost bypass circuit 18. To the secondary refrigerant evaporator 12,
After the frost of the secondary refrigerant evaporator 12 is melted and frosted, it is vaporized and vaporized by the primary refrigerant condenser 6 acting as an evaporator, and then returned to the primary refrigerant compressor 5. Therefore, as the defrosting heat source, the work of the primary refrigerant compressor 5 and the heat held by the medium (for example, outside air) that exchanges heat with the primary refrigerant condenser 6 are used. The defrosting ability will be greatly improved.

In the second basic configuration of the present invention (the invention of claim 2), as means for solving the above problems, a primary refrigerant compressor 5 for compressing the primary refrigerant x, and condensing and liquefying the primary refrigerant x. A high-temperature side refrigeration cycle A in which a primary refrigerant condenser 6, a primary refrigerant decompression mechanism 7 for decompressing the primary refrigerant x, and a primary refrigerant evaporator 8 for evaporating and evaporating the primary refrigerant x are sequentially connected via a refrigerant pipe 16. And a secondary refrigerant compressor 9 for compressing the secondary refrigerant y, a secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, and a secondary refrigerant y. A decompression mechanism 11 for the secondary refrigerant for reducing the pressure and an evaporator 12 for the secondary refrigerant for evaporating the secondary refrigerant y
And a low-temperature side refrigeration cycle B sequentially connected through a refrigerant pipe 17, the low-temperature side refrigeration cycle B is configured to be capable of reverse cycle operation, An air-cooled heat exchanger 19 for evaporating and evaporating the liquid refrigerant y flowing back to the secondary refrigerant compressor 9 during the reverse cycle operation is provided.

With the above configuration, during the defrosting operation, the high-temperature gas refrigerant (ie, hot gas) y discharged from the secondary refrigerant compressor 9 is supplied to the secondary refrigerant evaporator 12. After the frost of the secondary refrigerant evaporator 12 is melted and frosted, the air is evaporated and vaporized by the air-cooling heat exchanger 19 and then returned to the secondary refrigerant compressor 9. Therefore, as the heat source for defrosting, the work of the compressor 9 for the secondary refrigerant and the heat held by the medium (for example, indoor air) that exchanges heat with the air-cooling heat exchanger 19 are used. As a result, the defrosting ability is greatly improved.

When the air-cooling heat exchanger 19 is also used as the primary refrigerant condenser 6 in the high-temperature side refrigeration cycle A as in the third aspect of the present invention, the secondary refrigerant condenser 12 is used during the defrosting operation. Thus, the secondary refrigerant y condensed and liquefied can be evaporated and vaporized in the primary refrigerant condenser 6, which can contribute to a reduction in the number of parts and cost. In this case, the heat held by the outside air is used as a heat source for defrosting.

In a third basic configuration of the present invention (invention of claim 4), as means for solving the above problems, a primary refrigerant compressor 5 for compressing the primary refrigerant x, and condensing and liquefying the primary refrigerant x. A high-temperature side refrigeration cycle A in which a primary refrigerant condenser 6, a primary refrigerant decompression mechanism 7 for decompressing the primary refrigerant x, and a primary refrigerant evaporator 8 for evaporating and evaporating the primary refrigerant x are sequentially connected via a refrigerant pipe 16. And a secondary refrigerant compressor 9 for compressing the secondary refrigerant y, a secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, and a secondary refrigerant y. A decompression mechanism 11 for the secondary refrigerant for reducing the pressure and an evaporator 12 for the secondary refrigerant for evaporating the secondary refrigerant y
And a low-temperature refrigeration cycle B, which is sequentially connected via a refrigerant pipe 17, wherein the high-temperature refrigeration cycle A and the low-temperature refrigeration cycle B can be operated in reverse cycle. .

With the above configuration, during the defrosting operation, the high-temperature gas refrigerant (ie, hot gas) y discharged from the secondary refrigerant compressor 9 is supplied to the secondary refrigerant evaporator 12. Is supplied to the secondary refrigerant evaporator 12 to melt the frost, and after being evaporated and vaporized by the secondary refrigerant condenser 10 acting as an evaporator, is returned to the secondary refrigerant compressor 9. At the same time, the high-temperature gas refrigerant (that is, hot gas) x discharged from the primary refrigerant compressor 5 is supplied to the primary refrigerant evaporator 8, and the secondary refrigerant condenser 10 evaporates the liquid refrigerant y. After being condensed and liquefied by the aid of vaporization, it is evaporated and vaporized by the primary refrigerant condenser 6 acting as an evaporator and returned to the primary refrigerant compressor 5. Accordingly, as the defrosting heat source, the work of the primary refrigerant compressor 5 and the secondary refrigerant compressor 9 and the heat of the medium (for example, outside air) that exchanges heat with the primary refrigerant condenser 6 are provided. Since it is used, the defrosting ability is greatly improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First Embodiment (corresponding to claim 1) FIG. 1 shows a binary refrigeration apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, this binary refrigeration system
The configuration is the same as that already described in the section of the prior art.

That is, this binary refrigerating apparatus is used as a showcase refrigerating apparatus, and comprises a primary refrigerant compressor 5 for compressing a primary refrigerant x, and a primary refrigerant condenser 6 for condensing and liquefying the primary refrigerant x. A high-temperature side refrigeration cycle A in which a primary refrigerant decompression mechanism 7 for decompressing the primary refrigerant x and a primary refrigerant evaporator 8 for evaporating and evaporating the primary refrigerant x are sequentially connected through a refrigerant pipe 16; , A secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, and a secondary refrigerant for decompressing the secondary refrigerant y. A low-temperature refrigeration cycle B in which a pressure reducing mechanism 11 and a secondary refrigerant evaporator 12 for evaporating and evaporating the secondary refrigerant y are sequentially connected via a refrigerant pipe 17.
It is comprised including. Reference numeral 13 denotes a cooling fan for cooling the condenser 6 for the primary refrigerant.

The compressor 5 for the primary refrigerant and the condenser 6 for the primary refrigerant constitute the outdoor unit 1. The decompression mechanism 7 for the primary refrigerant, the evaporator 8 for the primary refrigerant, the compressor 9 for the secondary refrigerant and The condenser 10 for the secondary refrigerant constitutes the cascade unit 2, and the decompression mechanism 11 for the secondary refrigerant and the evaporator 12 for the secondary refrigerant constitute the refrigeration unit 3 for the showcase. The showcase refrigeration unit 3 is installed in the showcase arrangement room 4.

In this two-way refrigeration system, a four-way switching valve 20 is provided on the discharge side of the primary refrigerant compressor 5 in the high-temperature side refrigeration cycle A, so that the reverse cycle operation of the high-temperature side refrigeration cycle A is performed. Is configured as possible,
During the reverse cycle operation of the high-temperature side refrigeration cycle A, the gas refrigerant x discharged from the primary refrigerant compressor 5 is bypassed to the downstream side of the primary refrigerant pressure reducing mechanism 7 via the secondary refrigerant evaporator 12. A defrost bypass circuit 18 is provided. A heating heat exchanger 21 configured to be able to exchange heat with the secondary refrigerant evaporator 12 is provided in the middle of the defrost bypass circuit 18. Reference numeral 22 denotes a check valve that permits only the flow of the refrigerant from the primary refrigerant condenser 6 to the primary refrigerant pressure reducing mechanism 7, and 23 denotes a pressure reducing mechanism connected in parallel with the check valve 22, and the primary pressure during cooling operation. Refrigerant x
Flows through the check valve 22, and the primary refrigerant x flows through the pressure reducing mechanism 23 during the defrosting operation.
Reference numeral 24 denotes an open / close valve provided only at the time of defrosting operation provided on the inlet side of the bypass circuit 18 for defrosting, and reference numeral 25 designates an open / close valve provided at the outlet side of the bypass circuit 18 for defrosting. This is a check valve that allows only refrigerant flow. Instead of the on-off valve 24 and the check valve 25, a three-way valve may be provided at a branch point between the high-temperature refrigeration cycle A and the defrost bypass circuit 18.

The binary refrigeration system configured as described above has
It works as follows.

(I) At the time of cooling operation At this time, the four-way switching valve 20 is switched to the forward cycle side, the on-off valve 24 is closed, the primary refrigerant compressor 5, the secondary refrigerant compressor 9, and the cooling fan 13 is operating.

The primary refrigerant x sent from the primary refrigerant compressor 5 under pressure is supplied to the four-way switching valve 20 as shown by the solid arrows in FIG.
Is supplied to the condenser 6 for the primary refrigerant, and is condensed and liquefied there. After passing through the check valve 22, the pressure is reduced by the pressure reducing mechanism 7 for the primary refrigerant, and thereafter, it is evaporated and vaporized by the evaporator 8 for the primary refrigerant.
The refrigerant is returned to the primary refrigerant compressor 5 through the four-way switching valve 20.

On the other hand, as shown by a solid line arrow in FIG. 1, the secondary refrigerant y pressure-fed from the secondary refrigerant compressor 9 is transferred to the primary refrigerant evaporator 8 in the secondary refrigerant condenser 10 by heat. After being condensed and liquefied by the exchange, the pressure is reduced by the secondary refrigerant decompression mechanism 11, then evaporated and vaporized by the secondary refrigerant evaporator 12, and returned to the secondary refrigerant compressor 9. Therefore, the secondary refrigerant y which has been cooled down by heat exchange with the primary refrigerant evaporator 8
Is evaporated and vaporized in the secondary refrigerant evaporator 12, so that the cooling effect of the secondary refrigerant evaporator 12 is greatly improved.

(II) During defrosting operation At this time, the four-way switching valve 20 is switched to the reverse cycle side, the on-off valve 24 is opened, the primary refrigerant compressor 5 and the cooling fan 13 are operated, and the secondary The operation of the refrigerant compressor 9 is stopped.

The high-temperature gas refrigerant (ie, hot gas) x discharged from the primary refrigerant compressor 5 passes through the four-way switching valve 20 and then passes through the defrost bypass circuit 1 as shown by the dotted line in FIG.
8, is supplied to the secondary refrigerant evaporator 12, melts frost on the secondary refrigerant evaporator 12, and is then supplied to the primary refrigerant condenser 6 acting as an evaporator via the pressure reducing mechanism 23. ,
Then, after being vaporized and vaporized, the refrigerant is returned to the primary refrigerant compressor 5 via the four-way switching valve 20. Therefore, as the heat source for defrosting, the work of the compressor 5 for the primary refrigerant and the heat held by the outside air, which is a medium for exchanging heat with the condenser 6 for the primary refrigerant, are used. The ability will be greatly improved.

In the case of the evaporator in the showcase refrigeration system, since a heat exchanger having a relatively large fin pitch is used, the defrosting is performed in a short time with a high defrosting ability as in the present embodiment. However, since frost drops only due to the frost around the heat transfer tubes, frost does not remain. In addition, in the case of a showcase, since food and the like are displayed, it is possible to satisfy the requirement that a shorter defrosting time is desirable.

In addition, since the defrosting is performed not by the defrosting method using the electric heater but by the heat carried by the refrigerant, the running cost is not increased and the periodic maintenance is unnecessary. Become.

Second Embodiment (Corresponding to Claim 2) FIG. 2 shows a binary refrigeration apparatus according to a second embodiment of the present invention.

In this case, the high-temperature side refrigeration cycle A includes a primary refrigerant compressor 5 for compressing the primary refrigerant x, a primary refrigerant condenser 6 for condensing and liquefying the primary refrigerant x, and a primary refrigerant decompression for reducing the primary refrigerant x. A mechanism 7 and a primary refrigerant evaporator 8 for evaporating and evaporating the primary refrigerant x are sequentially connected via a refrigerant pipe 16.

On the other hand, a four-way switching valve 26 is provided on the discharge side of the secondary refrigerant compressor 9 in the low-temperature side refrigeration cycle B to enable reverse cycle operation. An air-cooled heat exchanger 19 for evaporating and evaporating the liquid refrigerant y flowing back to the secondary refrigerant compressor 9 during operation is provided. Note that the defrost bypass circuit 18 in the first embodiment is omitted. Reference numeral 27 denotes a cooling fan of the air-cooled heat exchanger 19, and reference numeral 28 denotes a secondary refrigerant pressure reducing mechanism 11.
A check valve 29 connected in parallel to allow the refrigerant to flow only during the defrosting operation; 29 is a check valve that allows only the refrigerant to flow from the secondary refrigerant condenser 10 to the secondary refrigerant pressure reducing mechanism 11;
Is a pressure reducing mechanism connected in parallel with the check valve 29. During the cooling operation, the secondary refrigerant y flows through the check valve 29,
During the defrosting operation, the secondary refrigerant y flows through the pressure reducing mechanism 30. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

The binary refrigeration system configured as described above has
It works as follows.

(I) Cooling operation At this time, the four-way switching valve 26 is switched to the forward cycle side, and the primary refrigerant compressor 5, the secondary refrigerant compressor 9, and the cooling fans 13, 27 are operated. .

The primary refrigerant x fed from the primary refrigerant compressor 5 is supplied to the primary refrigerant condenser 6 where it is condensed and liquefied, as shown by the solid arrow in FIG. The pressure is reduced at 7, then evaporated and vaporized at the primary refrigerant evaporator 8 and returned to the primary refrigerant compressor 5.

On the other hand, the secondary refrigerant y pressure-fed from the secondary refrigerant compressor 9 passes through the four-way switching valve 26 and then from the cooling fan 27 in the air-cooled heat exchanger 19 as shown by the solid arrow in FIG. Is cooled by the cooling air of the
Is condensed and liquefied by heat exchange with the primary refrigerant evaporator 8, passes through the check valve 29, and then the secondary refrigerant pressure reducing mechanism 11
After that, the refrigerant is evaporated and vaporized by the secondary refrigerant evaporator 12 and returned to the secondary refrigerant compressor 9 via the four-way switching valve 26. Therefore, the secondary refrigerant y whose temperature has been lowered by heat exchange with the primary refrigerant evaporator 8 is evaporated and vaporized in the secondary refrigerant evaporator 12, so that the cooling effect of the secondary refrigerant evaporator 12 is greatly improved. It will be. In this case, the air-cooled heat exchanger 19 pre-cools the refrigerant supplied to the secondary refrigerant condenser 10.

(II) Defrosting Operation At this time, the four-way switching valve 20 is switched to the reverse cycle side, the operation of the primary refrigerant compressor 5 and the cooling fan 13 is stopped, and the operation of the secondary refrigerant compressor 9 and the cooling The fan 27 is operating.

The high-temperature gas refrigerant (ie, hot gas) x discharged from the secondary refrigerant compressor 9 passes through a four-way switching valve 26 as shown by a dotted line in FIG. Is supplied to the secondary refrigerant evaporator 12 to melt the frost,
It is supplied to the air-cooled heat exchanger 19 acting as an evaporator via the check valve 28 and the pressure reducing mechanism 30, where it is evaporated and vaporized and then returned to the secondary refrigerant compressor 9 via the four-way switching valve 26. It will be. Therefore, as a defrost heat source,
Since the work of the compressor 9 for the secondary refrigerant and the heat held by the indoor air, which is a medium that exchanges heat with the air-cooled heat exchanger 19, are used, the defrosting ability is greatly improved. .

In the case of an evaporator in a refrigeration system for a showcase, a heat exchanger having a relatively large fin pitch is used. However, since frost drops only due to the frost around the heat transfer tubes, frost does not remain. In addition, in the case of a showcase, since food and the like are displayed, it is possible to satisfy the requirement that a shorter defrosting time is desirable.

Further, since the defrosting is performed not by the defrosting method using the electric heater but by the heat carried by the refrigerant, the running cost is not increased and the periodic maintenance is unnecessary. Become.

Third Embodiment (corresponding to claim 3) FIG. 3 shows a binary refrigeration apparatus according to a third embodiment of the present invention.

In this case, the cascade unit 2 is disposed in the outdoor unit 1 and branches off from the position on the outlet side of the pressure reducing mechanism 30 during the defrosting operation in the low-temperature side refrigeration cycle B via the three-way valve 31, and the high-temperature The first defrosting operation circuit 32 reaches a position on the inlet side of the primary refrigerant condenser 6 during the defrosting operation in the side refrigeration cycle A, and the primary refrigerant condenser 6 for the defrosting operation in the high temperature side refrigeration cycle A. Of the secondary refrigerant condenser 1 during the defrosting operation in the low-temperature side refrigeration cycle B from the position on the outlet side of the
A second defrosting operation circuit 34 that reaches a position on the exit side of 0 is additionally provided. During the defrosting operation, the secondary refrigerant y is supplied to the secondary refrigerant condenser 10 via the pressure reducing mechanism 30, the first defrosting operation circuit 32, the primary refrigerant condenser 6, and the second defrosting operation circuit. It will be distributed to the exit side. The air-cooled heat exchanger 19 and the cooling fan 27 in the second embodiment are omitted. That is, the air-cooled heat exchanger 19 in the second embodiment is configured to be also used as the primary refrigerant condenser 6. Other configurations are the first
The description is omitted because it is the same as in the second embodiment.

The binary refrigeration system configured as described above has:
It works as follows.

(I) At the time of cooling operation At this time, the four-way switching valve 26 is switched to the normal cycle side, and the three-way valves 31 and 33 are switched to the low-temperature side refrigeration cycle B side and the high-temperature side refrigeration cycle A side. Compressor 5, secondary refrigerant compressor 9, and cooling fan 13 are operating.

The primary refrigerant x fed from the primary refrigerant compressor 5 is supplied to a primary refrigerant condenser 6 where it is condensed and liquefied as shown by a solid line arrow in FIG. The pressure is reduced at 7, then evaporated and vaporized at the primary refrigerant evaporator 8 and returned to the primary refrigerant compressor 5.

On the other hand, the secondary refrigerant y pressure-fed from the secondary refrigerant compressor 9 is supplied to the secondary refrigerant condenser 10 through the four-way switching valve 26 as shown by the solid arrow in FIG. Then, it is condensed and liquefied by heat exchange with the primary refrigerant evaporator 8, passes through a check valve 29, is decompressed by the secondary refrigerant depressurizing mechanism 11, and is then evaporated and vaporized by the secondary refrigerant evaporator 12, and is subjected to four-way The refrigerant is returned to the secondary refrigerant compressor 9 via the switching valve 26.
Therefore, the secondary refrigerant y whose temperature has been lowered by heat exchange with the primary refrigerant evaporator 8 is evaporated and vaporized in the secondary refrigerant evaporator 12, so that the cooling effect of the secondary refrigerant evaporator 12 is greatly improved. It will be.

(II) During defrosting operation At this time, the four-way switching valve 20 is switched to the reverse cycle side, and the three-way valves 31, 33 are switched to the first and second defrosting operation circuits 32, 34. The operation of the primary refrigerant compressor 5 is stopped, and the operation of the secondary refrigerant compressor 9 and the cooling fan 13
Is driving.

The high-temperature gas refrigerant (that is, hot gas) x discharged from the secondary refrigerant compressor 9 passes through a four-way switching valve 26 as shown by a dotted line in FIG. Is supplied to the secondary refrigerant evaporator 12 to melt the frost,
Check valve 28, pressure reducing mechanism 30, and first defrosting operation circuit 3
And a condenser 6 for the primary refrigerant acting as an evaporator
After being evaporated and vaporized there, it is returned to the secondary refrigerant compressor 9 via the second defrosting operation circuit 34 and the four-way switching valve 26. Therefore, as the heat source for defrosting, the work of the compressor 9 for the secondary refrigerant and the heat held by the outside air, which is a medium that exchanges heat with the condenser 6 for the primary refrigerant, are used. The frost capacity will be greatly improved.

In the case of the evaporator in the showcase refrigeration system, since a heat exchanger having a relatively large fin pitch is used, as in the present embodiment, defrosting is performed in a short time with a high defrosting ability. However, since frost drops only due to the frost around the heat transfer tubes, frost does not remain. In addition, in the case of a showcase, since food and the like are displayed, it is possible to satisfy the requirement that a shorter defrosting time is desirable.

Further, since the defrosting is performed not by the defrosting method using the electric heater but by the heat carried by the refrigerant, the running cost is not increased and the periodic maintenance is unnecessary. Become.

Fourth Embodiment (corresponding to claim 4) FIG. 4 shows a binary refrigeration apparatus according to a fourth embodiment of the present invention.

In this case, four-way switching valves 20 and 26 are provided on the discharge side of the primary refrigerant compressor 5 and the secondary refrigerant compressor 9 in the high-temperature refrigeration cycle A and the low-temperature refrigeration cycle B, respectively. Both A and B are configured to enable reverse cycle operation. Reference numeral 28 denotes a check valve connected in parallel with the secondary refrigerant pressure reducing mechanism 11 and allowing the refrigerant to flow only during the defrosting operation. Reference numeral 29 denotes a refrigerant from the secondary refrigerant condenser 10 to the secondary refrigerant pressure reducing mechanism 11. A check valve allowing only circulation, 30 is a pressure reducing mechanism connected in parallel with the check valve 29,
A check valve 35 is connected in parallel with the primary refrigerant pressure reducing mechanism 7. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

The binary refrigeration system configured as described above has
It works as follows.

(I) Cooling operation At this time, the four-way switching valves 20 and 26 are switched to the normal cycle side, and the primary refrigerant compressor 5, the secondary refrigerant compressor 9 and the cooling fan 13 are operated. .

The primary refrigerant x pressure-fed from the primary refrigerant compressor 5 is supplied to the four-way switching valve 20 as shown by a solid line arrow in FIG.
Is supplied to the primary refrigerant condenser 6, where it is condensed and liquefied. Then, it is depressurized by the primary refrigerant decompression mechanism 7 through the check valve 22, then is vaporized and vaporized by the primary refrigerant evaporator 8, and is switched in four ways. The refrigerant is returned to the primary refrigerant compressor 5 through the valve 20.

On the other hand, the secondary refrigerant y pressure-fed from the secondary refrigerant compressor 9 is supplied to the secondary refrigerant condenser 10 through the four-way switching valve 26 as shown by the solid arrow in FIG. Then, it is condensed and liquefied by heat exchange with the primary refrigerant evaporator 8, passes through a check valve 29, is decompressed by the secondary refrigerant depressurizing mechanism 11, and is then evaporated and vaporized by the secondary refrigerant evaporator 12, and is subjected to four-way The refrigerant is returned to the secondary refrigerant compressor 9 via the switching valve 26.
Therefore, the secondary refrigerant y whose temperature has been lowered by heat exchange with the primary refrigerant evaporator 8 is evaporated and vaporized in the secondary refrigerant evaporator 12, so that the cooling effect of the secondary refrigerant evaporator 12 is greatly improved. It will be.

(II) At the time of defrosting operation At this time, the four-way switching valves 20 and 26 are switched to the reverse cycle side, and the primary refrigerant compressor 5, the secondary refrigerant compressor 9 and the cooling fan 13 are operated. I have.

The high-temperature gas refrigerant (ie, hot gas) x discharged from the primary refrigerant compressor 5 is supplied to the primary refrigerant evaporator 8 through the four-way switching valve 20, as shown by the dotted line in FIG. The refrigerant is supplied to the primary refrigerant condenser 6 acting as an evaporator via the check valve 35 and the pressure reducing mechanism 23, and is evaporated and vaporized there, and then returned to the primary refrigerant compressor 5 via the four-way switching valve 20. Will be done.

On the other hand, the high-temperature gas refrigerant (ie, hot gas) x discharged from the secondary refrigerant compressor 9 passes through the four-way switching valve 26 as shown by the dotted line in FIG. After being supplied to the evaporator 12 and thawing the frost on the secondary refrigerant evaporator 12, the secondary refrigerant is supplied to the secondary refrigerant condenser 10 acting as an evaporator via the check valve 28 and the pressure reducing mechanism 30, Then, the heat is exchanged with the hot gas x supplied to the primary refrigerant evaporator 8 to evaporate and then return to the secondary refrigerant compressor 9 via the four-way switching valve 26. Therefore, as the defrosting heat source, the work of the primary refrigerant compressor 5 and the secondary refrigerant compressor 9 and the heat held by the outside air, which is a medium that exchanges heat with the primary refrigerant condenser 6, are used. Therefore, the defrosting ability is greatly improved.

In the case of the evaporator in the showcase refrigeration system, a heat exchanger having a relatively large fin pitch is used. However, since frost drops only due to the frost around the heat transfer tubes, frost does not remain. In addition, in the case of a showcase, since food and the like are displayed, it is possible to satisfy the requirement that a shorter defrosting time is desirable.

In addition, since the defrosting is performed not by the defrosting method using the electric heater but by the heat carried by the refrigerant, the running cost is not increased and the periodic maintenance is unnecessary. Become.

In the above embodiment, the case where the dual refrigerating apparatus is used as a showcase refrigerating apparatus has been described, but the dual refrigerating apparatus of the present invention can be used for other purposes.

[0062]

According to the first basic configuration of the present invention (the invention of claim 1), the primary refrigerant compressor 5 for compressing the primary refrigerant x, and the primary refrigerant condenser 6 for condensing and liquefying the primary refrigerant x. ,
A high temperature side refrigeration cycle A in which a primary refrigerant decompression mechanism 7 for decompressing the primary refrigerant x and a primary refrigerant evaporator 8 for evaporating and evaporating the primary refrigerant x are sequentially connected via a refrigerant pipe 16.
And a secondary refrigerant compressor 9 for compressing the secondary refrigerant y, a secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, and a secondary refrigerant y. A binary refrigeration system including a low-temperature side refrigeration cycle B in which a secondary refrigerant decompression mechanism 11 for reducing pressure and a secondary refrigerant evaporator 12 for evaporating and evaporating the secondary refrigerant y are sequentially connected via a refrigerant pipe 17. , The high-temperature side refrigeration unit A is configured to be capable of reverse cycle operation, and the primary refrigerant compressor 5
The refrigerant gas x discharged from the secondary refrigerant evaporator 12
And a bypass circuit 18 for defrosting is provided for bypassing to the downstream side of the primary refrigerant decompression mechanism 7 through the above. In the defrosting operation, a high-temperature gas refrigerant discharged from the primary refrigerant compressor 5 (that is, hot gas refrigerant) Gas) x is the defrost bypass circuit 1
After being supplied to the secondary refrigerant evaporator 12 through the secondary evaporator 8 and thawing the frost of the secondary refrigerant evaporator 12, the primary refrigerant is evaporated and vaporized by the primary refrigerant condenser 6 acting as an evaporator. As a heat source for defrosting, the work amount of the primary refrigerant compressor 5 and the heat retained in a medium (for example, outside air) that exchanges heat with the primary refrigerant condenser 6 are used as heat sources for defrosting. Can be used, and there is an excellent effect that the defrosting ability is greatly improved and the defrosting time can be shortened.
Moreover, since the defrosting is performed by the heat carried by the refrigerant instead of the defrosting method using the electric heater, the running cost is not increased, and the periodic maintenance is unnecessary. There is also.

According to the second basic configuration of the present invention (the invention of claim 2), the primary refrigerant compressor 5 for compressing the primary refrigerant x, the primary refrigerant condenser 6 for condensing and liquefying the primary refrigerant x, the primary refrigerant The refrigerant pipe 1 includes a primary refrigerant decompression mechanism 7 for decompressing the refrigerant x and a primary refrigerant evaporator 8 for evaporating the primary refrigerant x.
6, a high-temperature refrigeration cycle A sequentially connected through
A secondary refrigerant compressor 9 for compressing the secondary refrigerant y, a secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, and depressurizing the secondary refrigerant y. In a binary refrigeration apparatus including a low-temperature side refrigeration cycle B in which a secondary refrigerant decompression mechanism 11 and a secondary refrigerant evaporator 12 for evaporating and evaporating the secondary refrigerant y are sequentially connected via a refrigerant pipe 17, An air-cooled heat exchanger configured to enable the low-temperature side refrigeration cycle B to perform a reverse cycle operation and evaporate and evaporate the liquid refrigerant y flowing back to the secondary refrigerant compressor 9 during the reverse cycle operation of the low-temperature side refrigeration cycle B. At the time of the defrosting operation, a high-temperature gas refrigerant (that is, hot gas) y discharged from the secondary refrigerant compressor 9 is supplied to the secondary refrigerant evaporator 12 and the secondary refrigerant evaporator 12 is attached thereto. Evaporator for refrigerant 12
After the frost is melted, the refrigerant is evaporated and vaporized in the air-cooled heat exchanger 19 and then returned to the secondary refrigerant compressor 9, so that the secondary refrigerant compressor 9 is used as a defrosting heat source. The work amount and the heat held by the medium (for example, indoor air) that exchanges heat with the air-cooling heat exchanger 19 can be used, and the defrosting ability is greatly improved and the defrosting time can be shortened. effective. Moreover, since the defrosting is performed by the heat carried by the refrigerant instead of the defrosting method using the electric heater, the running cost is not increased, and the periodic maintenance is unnecessary. There is also.

When the air-cooling heat exchanger 19 is also used as the primary refrigerant condenser 6 in the high-temperature side refrigeration cycle A as in the third aspect of the present invention, the secondary refrigerant condenser 12 is used during the defrosting operation. Thus, the secondary refrigerant y condensed and liquefied can be evaporated and vaporized in the primary refrigerant condenser 6, which can contribute to a reduction in the number of parts and cost. In this case, the heat held by the outside air is used as a heat source for defrosting.

According to the third basic configuration of the present invention (the invention of claim 4), the primary refrigerant compressor 5 for compressing the primary refrigerant x, the primary refrigerant condenser 6 for condensing and liquefying the primary refrigerant x, the primary refrigerant The refrigerant pipe 1 includes a primary refrigerant decompression mechanism 7 for decompressing the refrigerant x and a primary refrigerant evaporator 8 for evaporating the primary refrigerant x.
6, a high-temperature refrigeration cycle A sequentially connected through
A secondary refrigerant compressor 9 for compressing the secondary refrigerant y, a secondary refrigerant condenser 10 for condensing and liquefying the secondary refrigerant y by heat exchange with the primary refrigerant evaporator 8, and depressurizing the secondary refrigerant y. In a binary refrigeration apparatus including a low-temperature side refrigeration cycle B in which a secondary refrigerant decompression mechanism 11 and a secondary refrigerant evaporator 12 for evaporating and evaporating the secondary refrigerant y are sequentially connected via a refrigerant pipe 17, The high-temperature side refrigeration cycle A and the low-temperature side refrigeration cycle B are configured to be capable of performing a reverse cycle operation. During the defrosting operation, a high-temperature gas refrigerant (that is, hot gas) discharged from the secondary refrigerant compressor 9 is used. ) Y is supplied to the secondary refrigerant evaporator 12, and after melting the frost of the secondary refrigerant evaporator 12, the secondary refrigerant condenser 1 acting as an evaporator
After being vaporized and vaporized at 0, the refrigerant is returned to the secondary refrigerant compressor 9 and the high-temperature gas refrigerant (that is, hot gas) x discharged from the primary refrigerant compressor 5 is supplied to the primary refrigerant evaporator 8. After being supplied and condensed and liquefied by assisting the evaporation and vaporization of the liquid refrigerant y in the secondary refrigerant condenser 10, the liquid refrigerant y is evaporated and vaporized in the primary refrigerant condenser 6 acting as an evaporator, and then used for the primary refrigerant. Since the refrigerant is returned to the compressor 5, as a defrosting heat source, the work amounts of the primary refrigerant compressor 5 and the secondary refrigerant compressor 9 and a medium that exchanges heat with the primary refrigerant condenser 6 (for example, , Outside air) can be used, and there is an excellent effect that the defrosting ability is greatly improved and the defrosting time can be shortened. Moreover, since the defrosting is performed by the heat carried by the refrigerant instead of the defrosting method using the electric heater, the running cost is not increased, and the periodic maintenance is unnecessary. There is also.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a binary refrigeration apparatus according to a first embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram of a binary refrigeration apparatus according to a second embodiment of the present invention.

FIG. 3 is a refrigerant circuit diagram of a binary refrigeration apparatus according to a third embodiment of the present invention.

FIG. 4 is a refrigerant circuit diagram of a binary refrigeration apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a refrigerant circuit diagram of a conventional binary refrigeration apparatus.

[Explanation of symbols]

5 is a primary refrigerant compressor, 6 is a primary refrigerant condenser, 7 is a primary refrigerant decompression mechanism, 8 is a primary refrigerant evaporator, 9 is a secondary refrigerant compressor, 10 is a secondary refrigerant condenser, 11 is a pressure reducing mechanism for a secondary refrigerant, 12 is an evaporator for a secondary refrigerant, 16 and 17 are refrigerant pipes, 18 is a defrost bypass circuit, 19 is an air-cooled heat exchanger, 20 and 26 are four-way switching valves, and A Is a high-temperature side refrigeration cycle, B is a low-temperature side refrigeration cycle, x is a primary refrigerant, and y is a secondary refrigerant.

Claims (4)

[Claims] 1. A primary refrigerant compressor (5) for compressing a primary refrigerant (x), a primary refrigerant condenser (6) for condensing and liquefying the primary refrigerant (x), and a primary refrigerant for decompressing the primary refrigerant (x). High-temperature refrigeration cycle (A) in which a pressure reducing mechanism (7) for use and a primary refrigerant evaporator (8) for evaporating and evaporating the primary refrigerant (x) are sequentially connected via a refrigerant pipe (16); A secondary refrigerant compressor (9) for compressing (y), a secondary refrigerant condenser (10) for condensing and liquefying the secondary refrigerant (y) by heat exchange with the primary refrigerant evaporator (8), Secondary refrigerant (y)
Low-temperature refrigeration cycle comprising a secondary refrigerant evaporator (12) for evaporating and evaporating the secondary refrigerant (y) and a secondary refrigerant evaporator (12) sequentially connected via a refrigerant pipe (17). (B), wherein the high-temperature refrigeration unit (A) is configured to be capable of reverse cycle operation, and the primary refrigeration unit (A) is configured to perform the primary cycle during reverse cycle operation of the high-temperature refrigeration cycle (A). The gas refrigerant (x) discharged from the refrigerant compressor (5) is supplied to the secondary refrigerant evaporator (1).
A binary refrigeration system comprising a defrosting bypass circuit (18) that bypasses the downstream side of the primary refrigerant pressure reducing mechanism (7) via 0). 2. A primary refrigerant compressor (5) for compressing a primary refrigerant (x), a primary refrigerant condenser (6) for condensing and liquefying the primary refrigerant (x), and a primary refrigerant for decompressing the primary refrigerant (x). High-temperature refrigeration cycle (A) in which a pressure reducing mechanism (7) for use and a primary refrigerant evaporator (8) for evaporating and evaporating the primary refrigerant (x) are sequentially connected via a refrigerant pipe (16); A secondary refrigerant compressor (9) for compressing (y), a secondary refrigerant condenser (10) for condensing and liquefying the secondary refrigerant (y) by heat exchange with the primary refrigerant evaporator (8), Secondary refrigerant (y)
Low-temperature refrigeration cycle comprising a secondary refrigerant evaporator (12) for evaporating and evaporating the secondary refrigerant (y) and a secondary refrigerant evaporator (12) sequentially connected via a refrigerant pipe (17). (B), wherein the low-temperature refrigeration cycle (B) is configured to be capable of performing a reverse cycle operation, and the secondary refrigeration cycle (B) is configured to perform the reverse cycle operation during the reverse cycle operation of the low-temperature refrigeration cycle (B). A binary refrigeration system comprising an air-cooled heat exchanger (19) for evaporating and evaporating a liquid refrigerant (y) flowing back to a refrigerant compressor (9). 3. A condenser (6) for a primary refrigerant in the high-temperature side refrigeration cycle (A), wherein the air-cooled heat exchanger (19) is provided.
3. The dual refrigeration apparatus according to claim 2, wherein the dual refrigeration apparatus is also used. 4. A primary refrigerant compressor (5) for compressing a primary refrigerant (x), a primary refrigerant condenser (6) for condensing and liquefying the primary refrigerant (x), a primary refrigerant for decompressing the primary refrigerant (x). High-temperature refrigeration cycle (A) in which a pressure reducing mechanism (7) for use and a primary refrigerant evaporator (8) for evaporating and evaporating the primary refrigerant (x) are sequentially connected via a refrigerant pipe (16); A secondary refrigerant compressor (9) for compressing (y), a secondary refrigerant condenser (10) for condensing and liquefying the secondary refrigerant (y) by heat exchange with the primary refrigerant evaporator (8), Secondary refrigerant (y)
Low-temperature refrigeration cycle comprising a secondary refrigerant evaporator (12) for evaporating and evaporating the secondary refrigerant (y) and a secondary refrigerant evaporator (12) sequentially connected via a refrigerant pipe (17). (B), wherein the high-temperature side refrigeration cycle (A) and the low-temperature side refrigeration cycle (B) are configured to be capable of reverse cycle operation.