JP2697376B2 - Defrost device for cooling system with binary refrigeration cycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces the energy consumption in a cooling device of a binary refrigeration system in which a plurality of low-temperature side cooling units and an outdoor unit of a waste heat treatment system serving as a heat source are cascaded. The present invention relates to a defrosting device that can perform efficient individual defrosting while performing efficient defrosting.

[0002]

2. Description of the Related Art In a defrosting apparatus for a cooling system having a plurality of unit closed refrigeration cycles in a single cooling unit, a closed refrigeration cycle for performing reverse cycle defrost removes waste heat from the closed refrigeration cycle during a cooling operation. A defrosting device to be used is known, for example, from Japanese Patent Application Laid-Open No. 64-38581. In this prior art, condensers constituting each closed refrigeration cycle are collectively configured so that heat exchange can be performed therebetween.

[0003]

Although the above prior art is applied to a cooling system having a unitary closed refrigeration cycle, it cannot be applied to a cooling system having a dual refrigeration cycle. When an extremely low temperature at which the evaporation temperature is minus several tens of degrees is required, the binary refrigeration cycle is more advantageous than the unitary refrigeration cycle.

[0004] Further, since the cooling device disclosed in the above-mentioned prior art is integrally formed, the cooling device becomes large in size when cooling a large cooling chamber and the like, and is cooled in one place. There is a problem that it is difficult to cool uniformly. In order to solve this problem, conventionally, a cooling device is configured by a plurality of cooling units to form a so-called low-temperature multi.

[0005] However, the defrost method as shown in the above-mentioned prior art cannot be applied to a low-temperature multi-system cooling device. This is because a condenser is separately provided for each cooling unit, and heat exchange with each other is impossible.
Therefore, in the conventional low-temperature multi-system cooling device, the heat recovery operation cannot be performed at the time of defrost, and the heat efficiency is poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling apparatus comprising a plurality of cooling units, each of which has a dual refrigeration cycle and a common low-temperature refrigerant system on the high-temperature side, so that heat during defrosting can be obtained. An object of the present invention is to provide a defrost device for a cooling device that enables a recovery operation.

[0007]

According to the present invention, a closed refrigeration cycle including an outdoor unit 2 having a low-pressure refrigerant forward path 21A and a low-pressure refrigerant return path 21B and a cascade condenser 6 is constructed, and the secondary side of the cascade condenser 6 has a low pressure. Refrigerant outward path 2
In a cooling device having a binary refrigeration cycle consisting of a plurality of cooling units 1A and 1B connected to the low-pressure refrigerant return path 21A and the low-pressure refrigerant return path 21B, the cooling unit 1A connected to the low-pressure refrigerant forward path 21A performs reverse cycle defrost operation,
When the cooling unit 1B connected to the lower side performs the cooling operation, the lower cooling unit 1B is piped in series so as to receive the low-pressure refrigerant from the outdoor unit 2 in series, and the superior refrigerant unit 1A,
A cooling unit having a dual refrigeration cycle, characterized in that a valve means 29 is provided for piping so as to receive the low-pressure refrigerant from the outdoor unit 2 in parallel when the lower cooling unit 1B performs the cooling operation together. It is a defrost device.

The present invention also provides a closed refrigeration cycle including an outdoor unit 2 having a low-pressure refrigerant outward path 21A and a low-pressure refrigerant return path 21B, and a cascade condenser 6. The secondary side of the cascade condenser 6 has a low-pressure refrigerant outward path 21A and a low-pressure refrigerant A plurality of cooling units 1A connected to the refrigerant return path 21B,
1B, the cooling unit 1A connected upstream of the low-pressure refrigerant outward path 21A performs a cooling operation and the cooling unit 1B connected downstream.
When performing the reverse cycle defrost operation, pipes are arranged so that the lower cooling unit 1B receives the low-pressure refrigerant from the outdoor unit 2 in series, and when the upper refrigerant unit 1A and the lower cooling unit 1B perform the cooling operation together, they are connected in parallel. A defrosting device for a cooling device having a binary refrigeration cycle, wherein a valve means 29 for piping so as to receive low-pressure refrigerant from the outdoor unit 2 is provided.

According to the present invention, the valve means 29 is provided so that the cascade condenser 6 in the well-known cooling unit 1A is provided.
In the middle of the low-pressure refrigerant outlet pipe for connecting the secondary-side refrigerant outlet to the low-pressure refrigerant return path 21B, the secondary branch connection point of the cascade condenser 6 in the cooling unit 1A, and the cascade condenser 6 in the lower cooling unit 1B. Low pressure refrigerant outward path 21 between the secondary side branch connection point
A four-way switching valve interposed in the middle of the low-pressure refrigerant outlet pipe when one of the upper and lower cooling units 1A and 1B is in a cooling operation and the other is in a reverse cycle defrost operation. And disconnect the middle of the low-pressure refrigerant outward path 21A, and connect the secondary-side refrigerant outlet of the cascade condenser 6 in the cooling unit 1A to the low-pressure refrigerant outward path 2A.
1A, while both superior and inferior cooling units 1
When both A and 1B are in the cooling operation, the valves are operated so as to conduct in the middle of the low-pressure refrigerant outlet pipe and the middle of the low-pressure refrigerant outward path 21A, respectively.

[0010]

According to the present invention, a plurality of cooling units 1A, 1
This is a cascade-connected binary refrigeration cycle in which an outdoor unit of a single refrigerant system is commonly connected to B, and the entire circuit is simplified by simplifying the refrigerant circuit.

The plurality of cooling units 1A and 1B can perform alternate individual or simultaneous defrost operations. In the case of individual defrost operation, the low-pressure refrigerant forward and return paths 21A and 21B of the outdoor unit 2 can be used. Energy saving operation can be performed by utilizing heat recovery. That is, in the cooling units 1A and 1B of the low-temperature system, the cooling unit 1 upstream of the low-pressure refrigerant from the outdoor unit 2
When A performs the defrost operation, the cooling unit 1B on the downstream side is supplied as a cooling heat source of the cascade condenser 6, and heat is recovered so as to increase the cooling capacity of the cooling unit 1B. When the downstream cooling unit 1B performs the defrost operation, the cooling waste heat generated in the upstream cooling unit 1A during the cooling operation is supplied to the cascade condenser 6 of the downstream cooling unit 1B acting as an evaporator. Therefore, the defrost capacity of the cooling unit 1B is increased.

Thus, by sharing the waste heat system, energy can be saved during the defrost operation.

According to the present invention, the valve means 2 is connected to the cascade condenser 6 of the upstream cooling unit 1A.
9, the operation is simplified because the piping system is simple and only the switching operation of the valve means 29 is added.

Further, in the case where a four-way switching valve is used as the valve means 29, there is no place in the low-pressure refrigerant system of the outdoor unit 2 where liquid refrigerant or gas refrigerant is confined at the time of valve switching operation. Therefore, it is possible to provide a device with high safety without a danger of causing a pressure rise.

[0015]

FIG. 1 is a schematic circuit diagram of a cooling apparatus according to a first embodiment of the present invention. Cooling room 27 installed indoors
A plurality of cooling units 1A and 1B arranged on the top wall portion of the casing 11 have the same structure, and the inside of the casing 11 is heat-insulated into two upper and lower chambers by a heat insulating wall 16 provided in the center, and the lower half is cooled. The upper half is inserted into the chamber 27 and protrudes out of the cooling chamber 27, and is fixed to the top wall while keeping the airtight.

The casing 11 has an air inlet 12 and an air outlet 13 at a right side wall and a left side wall facing the lower chamber.
Are respectively opened, while an air inlet 14 and an air outlet 15 are respectively opened in the right side wall and the top wall facing the upper chamber. In the lower chamber, the evaporator 9 and the blower 1
The expansion means 7, which is realized by a temperature-sensitive expansion valve formed by connecting a blower coil 3 and a check valve 20B in parallel with each other, is accommodated in the heat source side 4 of the upper chamber. A switching valve 28, a cascade condenser 6 having a primary-side refrigerant circulation part and a secondary-side refrigerant circulation part in a heat exchange manner,
The capillary tube 8 formed by connecting the check valves 20A in parallel and the backup fan 22 are housed.

The compressor 5, the four-way switching valve 28, the primary-side refrigerant flow section of the cascade condenser 6, the capillary tube 8, the temperature-sensitive expansion valve 7, and the evaporator 9 are connected in a circulating manner by a refrigerant pipe. A reversible refrigeration cycle is formed, the compressor 5 and the blower 10 are operated, and the air in the cooling chamber 27 flowing from the air inlet 12 while the four-way switching valve 28 is operated to the cooling side is supplied to the evaporator 9. When passing through, it is cooled to a low temperature and is sent out from the air outlet 13 into the cooling chamber 27 as cool air, thereby cooling the cooling chamber 27. On the other hand, waste heat generated in the cascade condenser 6 is released outside by the outdoor unit 2 described later. The flow of the refrigerant in this case is indicated by a solid arrow. In the cooling unit 1 having the structure described above, assembling of equipment and all assembly of refrigerant pipe connection are performed in a specialty factory, so-called factory assembled, and on the local side,
Only the installation of the unit and the pipe connection to the secondary-side refrigerant flow portion of the cascade condenser 6 are performed.

The outdoor unit 2 used in combination with the cooling unit 1 includes a compressor 17, a condenser 18, and an expansion valve 1.
9 and a fan 23 are accommodated in a casing, and a discharge port of the compressor 17 and a refrigerant inlet of the condenser 18 are connected by a gas pipe, and a refrigerant outlet of the condenser 18 and an inflow port of the expansion valve 19 are connected. Connect with a liquid tube. The outdoor unit 2 is installed outdoors, and the suction port of the compressor 17 and the outlet of the secondary-side refrigerant circulation portion of each cascade condenser 6 are connected by a low-pressure refrigerant return path 21B, and the outlet port of the expansion valve 19 and each cascade condenser 6 is a low-pressure refrigerant forward path 21
Connected by A. Thus, the compressor 17,
A well-known refrigeration cycle is formed by the condenser 18, the expansion valve 19, and the secondary-side refrigerant circulation portion of each cascade condenser 6, and waste heat taken by the cascade condenser 6 during the cooling operation is reduced by the operation of the fan 23. Is released outside through the wind that passes through.

FIG. 2 is a diagram showing two types of refrigerant cycles according to the embodiment shown in FIG. FIG. 2 (a) shows an apparatus in which the cooling device operates for cryogenic freezing. The evaporator 9 has an evaporation temperature of -40 ° C., the primary side of the cascade condenser 6 has a temperature of 15 ° C., and the secondary side has a temperature of 5 °. C, in a device designed so that the condensation temperature of the condenser 18 is 50 ° C. and operated for low-temperature refrigeration, as shown in FIG. 15 ° C, 5 ° C, 50 ° C
Is designed so that the condensing temperature of the primary refrigerant cycle is constant at, for example, 15 ° C. irrespective of the level of the evaporating temperature, and this is subjected to waste heat treatment via the outdoor unit 2. Become.

In the cooling apparatus shown in FIG. 1, the fan 22 is normally stopped and only the natural convection of the heat emitted from the cascade condenser 6 is dissipated indoors, so that the indoor temperature rises. To prevent Then, the temperature in the cooling chamber 27 is detected by the thermometer 24, and the compressor 5 is started and stopped to control the temperature to be constant. On the other hand, the outdoor unit 2 detects the refrigerant temperature thermo 25 at the inlet of the secondary-side refrigerant flow portion of the cascade condenser 6 and controls the compressor 17 to operate when this temperature rises to a temperature corresponding to overheating.

Further, the fan 22 detects the refrigerant temperature at the outlet of the primary refrigerant circulation portion of the cascade condenser 6 by the thermo 26 when the refrigerant temperature detected by the thermo 25 rises above a set value. When the outdoor unit 2 is in a state of insufficient capacity, the outdoor unit 2 is operated not only when the temperature of the outdoor unit 2 is insufficient but also when the outdoor unit 2 is in a shortage state. This is extremely advantageous because it can also function to prevent the capacity of 2 from increasing.

In connection with the cooling unit 1A which is connected well based on the flow direction of the low-pressure refrigerant in the low-pressure refrigerant outward path 21A, a valve means 29 realized by a four-way switching valve is provided. The four-way switching valve 29 is provided in the middle of a low-pressure refrigerant outlet pipe for connecting the secondary-side refrigerant outlet of the cascade condenser 6 to the low-pressure refrigerant return path 21B, and in both cooling units 1.
A and 1B are provided so as to be interposed in the middle of the low-pressure refrigerant outward path 21A between the branch connection points of the secondary refrigerant inlets of the cascade condensers 6 in the cascade condensers 6, respectively.
When the cooling operation is performed simultaneously with the cooling unit 1B, the valves are operated so that the connection in the valve body as shown by the solid line in FIG. 1 is performed. When the cooling operation is performed during the operation, the switching operation is performed so that the connection in the valve body as shown by the broken line is also performed.

The cooling unit 1A performs a defrost operation under the reverse refrigeration cycle by switching the four-way switching valve 28. At this time, the flow of the refrigerant is as shown in FIG.
Is as indicated by the dashed arrow.

In the first embodiment described above, the outdoor unit 2
As the operation control means, a method of detecting the temperature of the cooling chamber, predicting the load from this, and then starting and stopping the compressor 17 may be adopted. By using a dual refrigeration cycle cooling system, the cooling units 1A and 1B can reduce the compression ratio, not only extend the life of the compressor 5 but also improve the efficiency. The evaporation temperature on the next side can be increased to about + 5 ° C., and even if some water is mixed in the refrigerant of the refrigerant circuit relating to the outdoor unit 2, there is a concern that the expansion valve will be blocked due to freezing of the water. No local plumbing is required. In this case, the refrigerant on the secondary side of the cascade condenser 6 is not limited to the condensable gas refrigerant but may be brine.

The adoption of the binary refrigeration system also has the advantage that a refrigerant having a lower allowable temperature and less polluting the global environment can be used because the compression ratio is reduced.

FIGS. 3 and 4 show a second embodiment of the present invention,
FIG. 2 is a schematic structural diagram illustrating a cooling unit 1 according to the embodiment. 3 and 4 are similar to the above-described embodiments, and corresponding parts are denoted by the same reference numerals. It should be noted in FIG. 3 that in this embodiment, the fan 31 is connected in series with the primary side of the cascade condenser 6 on the heat source side 4.
Is connected to the air-cooled heat exchanger 30 for detecting the refrigerant temperature at the outlet of the primary-side refrigerant flow section of the cascade condenser 6 or the refrigerant temperature at the inlet of the secondary-side refrigerant flow section. When the thermo 25 detects that the temperature at the location is higher than the set value, the failure of the outdoor unit 2 or the capacity shortage is taken into consideration. 30 is operated for heat exchange. As described above, the operation of the air-cooled heat exchanger 30 is always stopped for emergency use, and the connection of the air-cooled heat exchanger 30 is not limited to the downstream side shown in FIG. Absent.

It should be noted in FIG. 4 that in this embodiment, the primary side of the cascade capacitor 6 is connected in series with:
The air-cooling heat exchanger 30 having the fan 31 is connected to the air-cooling heat exchanger 30. The three-way electromagnetic switching valve is provided in the middle of the gas pipe connecting the compressor 5 and the cascade condenser 6 to the coil connection point of the air-cooling heat exchanger 30. The switching means 32 is provided.
During normal operation, the solenoid valve 32 is operated so that the gas refrigerant flows to the side of the cascade condenser 6 indicated by the arrow, and is located downstream of the primary side of the cascade condenser 6 and the coil of the air-cooled heat exchanger 30. Thermo 24 for detecting the temperature of the refrigerant in the refrigerant liquid pipe or thermo 26 for detecting the temperature of the refrigerant at the inlet of the secondary-side refrigerant flow section of the cascade condenser 6
When a temperature higher than the set value is detected, a failure or insufficient capacity of the outdoor unit 2 is expected, so that the electromagnetic valve 32 is set so that the gas refrigerant flows to the air-cooled heat exchanger 30 shown by the arrow. At the same time as the switching operation, the fan 31 is operated to cause the air-cooled heat exchanger 30 to perform a heat exchange operation.

FIG. 5 is a schematic circuit diagram of an outdoor unit 2 according to a fourth embodiment of the present invention. This embodiment is similar to the previous embodiment and corresponding parts are denoted by the same reference numerals. In FIG. 5, it should be noted that the outdoor unit 2 has a water-cooled structure instead of an air-cooled structure, and a water-cooled shell-type heat exchanger is used for the condenser 18. The tower 33 is circularly connected to the tower 33 by a pipe having a pump 34 interposed therebetween. The outdoor unit 2 includes a condenser 18
It is possible to discharge waste heat on the primary side through the water to the outside of the room.

FIG. 6 is a schematic circuit diagram of a main part of a cooling unit 1A according to a fifth embodiment of the present invention. This fifth embodiment is similar to the previous embodiment, and corresponding parts are denoted by the same reference numerals. It should be noted in FIG.
9 is a two-way solenoid valve 35 provided in the middle of the low-pressure refrigerant outward path 21A.
And a three-way switching solenoid valve 36 interposed in the middle of the low-pressure refrigerant outlet pipe on the secondary side of the cascade condenser 6 and branched downstream from the two-way solenoid valve 35 in the low-pressure refrigerant outward path 21A. It is a point. When the cooling units 1A and 1B are operated for cooling, the valve means 29 opens the two-way solenoid valve 35 and operates the three-way switching solenoid valve 36.
Is operated to the conduction side of the solid arrow shown in FIG. On the other hand, when any one of the cooling units is subjected to the defrost operation, the two-way solenoid valve 35 is closed, and the three-way switching solenoid valve 36 is switched to the dashed arrow conduction side shown in FIG. In this way, the same refrigerant flow switching control as the four-way switching valve 28 shown in FIG. 1 can be performed.

FIG. 7 is a schematic circuit diagram of a cooling unit 1B according to a sixth embodiment of the present invention. The sixth embodiment of FIG. 7 is similar to the above-described embodiments, and corresponding parts are denoted by the same reference numerals. It should be noted in FIG. 7 that the cooling unit 1B is not an integral type, but is formed as a separate type in which the blower coil 3 and the heat source side 4 are separated. Such a cooling device having a separate type cooling unit is naturally included in the scope of the present invention, and the blower coil 3 is installed in the cooling chamber 27, and the heat source side 4 is attached to the outer wall of the cooling chamber 27, for example. It is installed indoors in close proximity.

[0031]

As described above in detail, according to the present invention, when one of the plurality of cooling units 1A and 1B performs the defrost operation and the other performs the cooling operation, the secondary side low-pressure refrigerant outgoing passage 21A. The switching connection is performed by the valve means 29 so that the secondary side of the cascade condenser 6 of the cooling unit 1A which is connected well is in series with the secondary side of the cascade condenser 6 of the lower cooling unit 1B. When the units 1A and 1B perform the simultaneous cooling operation, they are arranged in parallel, and the alternate defrost operation can be performed easily and reliably, and the cooling unit performing the cooling operation and the cooling unit performing the defrost operation are provided. Since heat is effectively exchanged between the two, energy for driving is saved.

According to the present invention, the alternate defrosting operation can be performed simply by switching a valve such as a four-way switching valve, so that control is easy and the apparatus cost is reduced. There is.

[Brief description of the drawings]

FIG. 1 is a device circuit diagram schematically showing a cooling device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing two types of refrigerant cycles according to the embodiment shown in FIG. 1;

FIG. 3 is a schematic circuit diagram of a cooling device according to a second embodiment of the present invention.

FIG. 4 is a schematic circuit diagram of a cooling device according to a third embodiment of the present invention.

FIG. 5 is a schematic circuit diagram of a cooling device according to a fourth embodiment of the present invention.

FIG. 6 is a schematic circuit diagram of a cooling device according to a fifth embodiment of the present invention.

FIG. 7 is a schematic circuit diagram of a cooling device according to a sixth embodiment of the present invention.

[Explanation of symbols]

 1A, 1B Cooling unit 2 Outdoor unit 6 Cascade condenser 21A Low-pressure refrigerant forward path 21B Low-pressure refrigerant return path 27 Cooling chamber 28 Four-way switching valve 29 Valve means

Claims (3)

(57) [Claims] 1. Low-pressure refrigerant outward path 21A, low-pressure refrigerant return path 21
B and a closed refrigeration cycle including the cascade condenser 6 and the cascade condenser 6
Is a low-pressure refrigerant outward path 21A and a low-pressure refrigerant return path 21
In a cooling device having a binary refrigeration cycle including a plurality of cooling units 1A and 1B connected to B, the cooling unit 1A connected to the lower side of the low-pressure refrigerant outward path 21A performs reverse cycle defrost operation and the cooling unit connected to the lower side. When the cooling operation is performed by the cooling unit 1B, the piping is arranged so that the lower cooling unit 1B receives the low-pressure refrigerant from the outdoor unit 2 in series,
When the superior refrigerant unit 1A and the inferior cooling unit 1B both perform a cooling operation, a valve means 29 for piping so as to receive the low-pressure refrigerant from the outdoor unit 2 in parallel is provided. Defrosting device for cooling device having. 2. Low pressure refrigerant outward path 21A, low pressure refrigerant return path 21
B and a closed refrigeration cycle including the cascade condenser 6 and the cascade condenser 6
Is a low-pressure refrigerant outward path 21A and a low-pressure refrigerant return path 21
In a cooling device having a binary refrigeration cycle composed of a plurality of cooling units 1A and 1B connected to B, the cooling unit 1A connected to the low pressure refrigerant outward path 21A upstream performs a cooling operation, and the cooling unit 1B connected to the downstream side is provided with the cooling unit 1B. When performing reverse cycle defrost operation, piping is performed so that the lower cooling unit 1B receives the low-pressure refrigerant from the outdoor unit 2 in series,
When the superior refrigerant unit 1A and the inferior cooling unit 1B both perform a cooling operation, a valve means 29 for piping so as to receive the low-pressure refrigerant from the outdoor unit 2 in parallel is provided. Defrosting device for cooling device having. 3. The valve means 29 is provided in the middle of a low-pressure refrigerant outlet pipe for connecting the secondary-side refrigerant outlet of the cascade condenser 6 in the good cooling unit 1A to the low-pressure refrigerant return path 21B, and in the cascade in the cooling unit 1A. A four-way switching valve interposed in the middle of the low-pressure refrigerant outward path 21A between the secondary branch connection point of the condenser 6 and the secondary branch connection point of the cascade condenser 6 in the lower cooling unit 1B. When one of the superior and inferior cooling units 1A and 1B is in the cooling operation and the other is in the reverse cycle defrost operation, the middle of the low-pressure refrigerant outlet pipe and the middle of the low-pressure refrigerant outward path 21A are disconnected, and
While the secondary-side refrigerant outlet of the cascade condenser 6 in the superior cooling unit 1A is connected to the low-pressure refrigerant outward path 21A, when both the superior and inferior cooling units 1A and 1B are performing a cooling operation, the low-pressure refrigerant outlet pipe and the middle are connected. The defrost device for a cooling device having a binary refrigeration cycle according to claim 1 or 2, wherein the valve operates as if each of the low-pressure refrigerant outgoing passages (21A) is electrically connected.