JPH06331241A - Defroster for binary refrigerating system - Google Patents

Abstract

(57) [Abstract] [Purpose] Defrost is performed quickly in a dual refrigeration system having a dual refrigeration cycle. [Structure] The outdoor unit 10 is installed outdoors, and the No.
The 1-cooling unit 11 is installed in the freezer.
The outdoor unit 10 constitutes a high temperature side refrigeration cycle together with the evaporator 40 of the cascade condenser 42 and the expansion valve 28. A solenoid valve SV1 is connected in parallel to the expansion valve 28 and is in an open state during defrosting. The solenoid valve SV2 is opened during defrosting, and the hot gas heated by the liquid refrigerant from the condenser 51 of the outside unit 10 is supplied from the drain pan heater 47 to the evaporator 45. Since the outside unit 10 side serves as an auxiliary heat source for defrosting, quick defrosting is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to one or more low temperature side refrigeration cycles and one high temperature side refrigeration cycle, which are thermally coupled via a cascade condenser provided for each low temperature side refrigeration cycle. The present invention relates to a defrosting device for a dual refrigeration system that forms a refrigeration cycle.

[0002]

2. Description of the Related Art Conventionally, a dual refrigeration cycle in which a low temperature side refrigeration cycle is installed in a freezer or the like and a high temperature side refrigeration cycle condenser is installed outdoors is easy to construct a refrigerant line. Therefore, it may be used in a refrigerating apparatus having a temperature range that can be realized by a unit refrigeration cycle.
Further, a refrigerating apparatus in which a plurality of low-temperature side refrigerating cycles are provided inside the refrigerator with a common high-temperature side refrigerating cycle is also disclosed, for example, in Japanese Patent Laid-Open No. 5-18647.

In order to cool the inside of the freezer to a desired low temperature, it is necessary to radiate the amount of heat absorbed by the evaporator of the refrigeration cycle by the outdoor condenser. When it is attempted to realize such an action as a heat pump with a single refrigeration cycle, the pipe line connecting the inside of the refrigerator and the outdoor condenser is required to be airtight enough to withstand a high degree of vacuum. . If only the high temperature side refrigerant pipes constituting the dual refrigeration cycle are arranged from the inside to the outside, the necessary airtightness conditions are relaxed, the construction is easy and the safety is enhanced. Even when a plurality of low temperature side refrigeration cycles are provided, the heat radiated from the condenser of the low temperature side refrigeration cycle is transferred by the high temperature side refrigerant, so the condensers of the high temperature side refrigeration cycle can be integrated into one. .

The prior art of Japanese Patent Laid-Open No. 5-18647 mentioned above constitutes a so-called low temperature multi-system with a plurality of low temperature side refrigeration cycles and a single high temperature side refrigeration cycle.
When the two low temperature side refrigeration cycles are defrosted,
The structure of the refrigerant circuit of the high temperature side refrigeration cycle is switched to achieve effective use of energy.

[0005]

Even if it is necessary to perform the defrost operation in the low temperature side refrigeration cycle of the dual refrigeration system having the dual refrigeration cycle, the high temperature side refrigeration cycle may continue the cooling operation. For example, even if one of the plurality of low temperature side refrigeration cycles enters the defrost operation, if the other low temperature side refrigeration cycle is in the cooling operation, the high temperature side refrigeration cycle needs to continue the cooling operation. Therefore, the low-temperature side refrigeration cycle that enters the defrost operation independently stops the supply of the refrigerant to the high-temperature side evaporator of the cascade condenser,
Bypassing the cold condenser and subsequent expansion valve,
I try to do simple defrosting with hot gas. However, with the hot gas simple defrost alone, the heat source of the defrost is insufficient, and the defrost takes time. In particular, during defrosting, the refrigerant tends to be laid in the condenser of the cascade condenser, and the refrigerant tends to run short as the defrosting operation progresses. Further, the one described in JP-A-5-18647 does not utilize the heat of the high temperature refrigerant of the high temperature side refrigeration cycle as an auxiliary heat source for defrost.

An object of the present invention is to provide a defrosting device for a dual refrigeration system, which supplies a supplementary heat source for defrosting by using a pipe or the like which constitutes a dual refrigeration cycle and enables quick defrosting. That is.

[0007]

According to the present invention, an evaporator 40 for a high temperature side refrigeration cycle and a condenser 41 for a low temperature side refrigeration cycle are provided.
In the defrosting device of the binary refrigeration system provided with the cascade condenser 42 that thermally couples and, the low-temperature side refrigeration cycle transfers hot gas during defrosting from the outlet side of the condenser 41 of the cascade condenser 42 to the inlet side of the evaporator 45. The high temperature side refrigerating cycle is provided with a hot gas circulating means SV2 which circulates, and an expansion valve function is provided between the outlet side of the condenser 51 and the inlet side of the evaporator 40 of the cascade condenser 42 during cooling of the low temperature side refrigerating cycle. A defrosting device for a dual refrigeration system, which has valve means 28 and SV1; 55 having a valve opening function at the time of defrosting.

Further, according to the present invention, in the defrosting device of the binary refrigeration system provided with the cascade condenser 42 for thermally coupling the evaporator 40 of the high temperature side refrigeration cycle and the condenser 41 of the low temperature side refrigeration cycle, the low temperature side refrigeration cycle is From the outlet side of the condenser 41 of the cascade condenser 42 to the evaporator 4
5 is provided with hot gas flow means SV2 for circulating hot gas at the time of defrosting, and the high temperature side refrigeration cycle is provided with the outlet side of the condenser 51 and the cascade condenser 42.
Between the inlet side of the evaporator 40 and the inlet side of the evaporator 40, the valve means 28, SV1; 55 having an expansion valve function at the time of cooling the low temperature side refrigeration cycle and having a valve opening function at the time of defrosting are provided. The MC 2 and the condenser 51 are provided in the single outdoor unit 10, and the low temperature side refrigeration cycle,
The valve means 28, SV1; 55 of the high temperature side refrigeration cycle,
And the cascade condenser 42 includes the cooling units 11, 12, 13 of the plurality of cooling units 11, 12, 13.
It is a defrosting device of a binary refrigeration system, which is provided in each.

Further, according to the present invention, the plurality of cooling units 1 are provided.
When all 1, 12, 13 are defrosted, the condenser 5
It has a control means for stopping the fan MF2 that ventilates to 1.

Further, according to the present invention, in the defrosting device of the binary refrigeration system provided with the cascade condenser 42 for thermally coupling the evaporator 40 of the high temperature side refrigeration cycle and the condenser 41 of the low temperature side refrigeration cycle, the low temperature side refrigeration cycle is , A reverse cycle defrost means 60, 70 for switching the flow direction of the refrigerant to a direction opposite to that at the time of cooling at the time of defrost, and the high temperature side refrigeration cycle has an outlet side of the condenser 51 and an inlet of the evaporator 40 of the cascade condenser 42. A defrosting device for a dual refrigeration system, which is provided with a valve means 28, SV1; 55 having an expansion valve function at the time of cooling of the low temperature side refrigeration cycle and having a valve opening function at the time of defrosting between them. .

Further, the present invention provides a defrosting device of a binary refrigeration system provided with a cascade condenser 42 for thermally coupling an evaporator 40 of the high temperature side refrigeration cycle and a condenser 41 of the low temperature side refrigeration cycle. Evaporator 4
5, a drain pan heater 47 is provided, and in the high temperature side refrigeration cycle, the refrigerant from the outlet side of the condenser 51 is supplied to the inlet side of the evaporator 40 of the cascade condenser 42 via the expansion mechanism 28 during cooling of the low temperature side refrigerant cycle. The drain pan heater 47 of the low temperature side refrigeration cycle during defrosting.
Is a defrosting device for a binary refrigeration system, which is equipped with switching means SV2, SV3 for switching so as to lead to.

Further, the present invention is a defrosting device of a binary refrigeration system provided with a cascade condenser 42 for thermally coupling an evaporator 40 of a high temperature side refrigeration cycle and a condenser 41 of a low temperature side refrigeration cycle, and Evaporator 4
The fan guard heater 65 is installed in the fan MF1 that ventilates the fan 5.
In the high temperature side refrigeration cycle, the refrigerant from the outlet side of the condenser 51 is supplied to the evaporator 4 of the cascade condenser 42 via the expansion mechanism 28 during cooling of the low temperature side refrigeration cycle.
A defrosting device for a dual refrigeration system, which is equipped with switching means SV2, SV3 that guides it to the inlet side of 0 and guides it to the fan guard heater 65 of the low temperature side refrigeration cycle during defrosting.

Further, according to the present invention, in the defrosting device of the binary refrigeration system provided with the cascade condenser 42 for thermally coupling the evaporator 40 of the high temperature side refrigeration cycle and the condenser 41 of the low temperature side refrigeration cycle, Evaporator 4
5, a fan guard heater 65 is provided to the drain pan heater 47 and the fan MF1 that ventilates the evaporator 45. The high temperature side refrigeration cycle uses the refrigerant from the outlet side of the condenser 51 to cool the low temperature side refrigeration cycle. Expansion mechanism 28
It is provided with switching means SV2, SV3 for guiding the gas to the inlet side of the evaporator 40 of the cascade condenser 42 via the rectifier and switching to the drain pan heater 47 and the fan guard heater 65 of the low temperature side refrigeration cycle during defrosting. It is a defrosting device for a refrigeration system.

The present invention is also directed to a defrosting device for a dual refrigeration system provided with a plurality of cascade condensers 42 and 82 for thermally coupling an evaporator 40 of a high temperature side refrigeration cycle and a condenser 41 of a plurality of low temperature side refrigeration cycles. On the outlet side of the condenser 51 of the high temperature side refrigeration cycle, opening / closing means SV5, S that opens during cooling of the low temperature side refrigeration cycle and closes during defrosting of at least one low temperature side refrigeration cycle.
V6 is provided and has an expansion valve function at the time of cooling of each low temperature side refrigeration cycle between the opening / closing means SV5, SV6 and the inlet side of the evaporators 40, 80 of the plurality of cascade condensers 42, 82, and each low temperature A defrosting device for a dual refrigeration system, characterized in that valve means SV1, 28; SV11, 83 having a valve opening function during defrosting of the side refrigeration cycle are provided, respectively.

[0015]

According to the present invention, the high temperature side refrigeration cycle and the low temperature side refrigeration cycle are the evaporator 40 of the high temperature side refrigeration cycle,
And the condenser 41 of the low temperature side refrigeration cycle is thermally coupled by the cascade condenser 42. The defrosting of the low temperature side refrigeration cycle is performed by the hot gas flow means SV2 that causes hot gas to flow from the outlet side of the condenser 40 of the cascade condenser 42 to the inlet side of the evaporator 45. In the high temperature side refrigeration cycle, between the outlet side of the condenser 51 and the inlet side of the evaporator 40 of the cascade condenser 42,
At the time of defrost, valve means 28, SV having a valve opening function
1; 55, the liquid refrigerant from the condenser 51 is directly supplied to the evaporator 40 of the cascade condenser 42 during defrosting. During defrosting of the low temperature side refrigeration cycle, the refrigerant of the low temperature side refrigeration cycle flows through the condenser 41 of the cascade condenser 42, and absorbs the heat of the refrigerant liquid of the high temperature side refrigeration cycle from the evaporator 40 of the high temperature side refrigeration cycle. The hot gas absorbing this heat as an auxiliary heat source is used by the hot gas flow means SV2 to cool the evaporator 4 of the low temperature side refrigeration cycle
5, the defrosting of the evaporator 45 can be performed quickly.

Further, according to the present invention, the liquid refrigerant from the single outdoor unit 10 is cooled by a plurality of cooling units 11, 12, 1.
Supply to 3. The valve means 28, SV1; 55 of the high temperature side refrigeration cycle in each cooling unit 11, 12, 13 operates as an expansion valve during cooling of the low temperature side refrigeration cycle in the cooling unit 11, 12, 13 and opens during defrosting. Speak. At the time of defrosting in the low temperature side refrigeration cycle, the liquid refrigerant from the outdoor unit 10 is supplied to the evaporator of the cascade condenser 42 without being depressurized, so that it can be effectively used as an auxiliary heat source.

Further, the cooling units 11, 12, 1 of the present invention
At the time of defrosting all three, the fan MF2 that ventilates the condenser 51 is stopped. As a result, the outside unit 1
The heat of the hot gas discharged from the compressor MC2 in 0 can be used more effectively as an auxiliary heat source for defrosting in the low temperature side refrigeration cycle.

According to the invention, the low temperature side refrigerating cycle switches the flow direction of the refrigerant at the time of defrosting in the opposite direction to that at the time of cooling. As a result, the condenser 41 of the cascade condenser 42 operates as an evaporator during defrosting,
The high temperature refrigerant of the high temperature side refrigeration cycle is used as an auxiliary heat source to absorb heat, and the evaporator 45 can be quickly defrosted.

Further, according to the present invention, the evaporator 45 of the low temperature side refrigeration cycle is provided with the drain pan heater 47.
Since the liquid refrigerant from the outlet side of the condenser 51 of the high temperature side refrigeration cycle is supplied to the drain pan heater 47, the drain pan heater 47 can be quickly heated by this auxiliary heat source to perform quick defrosting.

According to the invention, a fan MF1 for ventilation is provided near the condenser 45 of the low temperature side refrigeration cycle, and a fan guard heater 65 is provided around the fan MF1. The fan guard heater 65 prevents the fan MF1 for circulating the inside air from the evaporator 45 from freezing due to drainage of the evaporator 45 during defrosting. Since the liquid refrigerant from the condenser 51 of the high temperature side refrigeration cycle is supplied to the fan guard heater 65, quick defrosting can be performed by this auxiliary heat source.

Further, according to the present invention, a drain pan heater 47 and a fan guard heater 65 of the ventilation fan MF1 are provided near the evaporator 45 of the low temperature side refrigeration cycle. Drain pan heater 47 and fan guard heater 6
5, the condenser 5 of the high temperature side refrigeration cycle during defrosting
Since the liquid refrigerant is supplied from 1 to serve as an auxiliary heat source, quick heating can be performed.

Further, according to the present invention, the opening / closing means SV on the outlet side of the condenser 51 of the high temperature side refrigeration cycle at the time of defrosting at least one of the plurality of low temperature side refrigeration cycles.
5, SV6 is closed. Therefore, the low temperature side refrigeration cycle that performs the defrost operation and the low temperature side refrigeration cycle that performs the cooling operation are in a state of being coupled to each other via the evaporators 40 and 80 of the cascade condensers 42 and 82.
Due to the natural circulation of the refrigerant, heat is applied to the low-temperature side refrigeration cycle that performs the defrost operation from the low-temperature side refrigeration cycle that performs the cooling operation, and serves as an auxiliary heat source for the defrost, enabling quick defrost.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a refrigerant piping system diagram of an embodiment of the present invention, and FIG. 2 shows a layout of equipment. The outdoor unit 10, which is also called a chilled unit, is installed outdoors. N
o. 1 cooling unit 11, no. 2 cooling unit 12, no. A plurality of internal cooling units such as the 3 cooling unit 13 are installed in the same freezer 15. During the cooling operation of the dual refrigeration cycle, the liquid pipeline 2
The liquid refrigerant is passed through 0, 21, 22, and 23 to the outside unit 1
It is supplied to each cooling unit 11-13 from 0.
No. 1 into the cooling unit 11, the liquid pipe 21,
Liquid refrigerant is supplied through the pipe joint 25, the closing valve 26, and the liquid pipe 27. The supplied liquid refrigerant is decompressed by the expansion valve 28 and guided to the conduit 29. Outside unit 10
The gaseous refrigerant is returned to the via the gas lines 30, 31, 32, 33. No. The 1 cooling unit 11 is connected to the gas pipeline 31 via a pipe joint 35, a closing valve 36, and a pipeline 37. In the pipe line 37, the temperature sensitive tube 3
8 is attached to adjust the opening degree of the expansion valve 28. Pipeline 2
An evaporator 40 of the high temperature side refrigeration cycle is connected between 9 and the pipe 37.

The evaporator 40 constitutes a cascade condenser 42 together with the condenser 41. The condenser 41 is N
o. Compressor MC1 in 1 cooling unit 11, expansion valve 43, temperature sensing cylinder 44, evaporator 45, accumulator 46
Together with this, a low temperature side refrigeration cycle is configured. Temperature sensitive tube 44
Is provided on the outlet side of the evaporator 45 and adjusts the opening degree of the expansion valve 43.

A drain pan heater 47 is provided in the vicinity of the evaporator 45, and its inlet side is connected to the outlet side of the condenser 41 of the cascade condenser 42 and the expansion valve 43 via an electromagnetic valve SV2 which is a hot gas flow means. It is connected to the entrance side. The outlet side of the drain pan heater 47 is connected to the expansion valve 43.
Is connected between the outlet side and the inlet side of the evaporator 45. A fan MF1 is provided for the evaporator 45 for ventilation. An electromagnetic valve SV3 is provided in the liquid pipe 27, and opens when the compressor MC1 operates and closes when the compressor MC1 stops.

In the outside unit 10, a compressor MC2,
Condenser 51, accumulator 52 and constant pressure expansion valve 53
Is provided and constitutes a part of the high temperature side refrigeration cycle. A fan MF2 is provided for the condenser 51 for ventilation.

The following Table 1 shows the No. when the cooling units 11 to 13 are individually controlled in the embodiment of FIG. 1
The control state at the time of cooling the cooling unit 11 and at the time of defrosting is shown. When cooling, the solenoid valves SV1 and SV2 are OF
It is F, and it becomes ON at the time of defrosting.

[0028]

[Table 1]

When the solenoid valve SV1 is turned on during defrosting, the expansion valve 28 is bypassed and the liquid refrigerant from the condenser 51 of the outside unit 10 is supplied to the evaporator 40 via the pipe 29. No. The hot gas discharged from the compressor MC1 of the 1-cooling unit 11 is heated by the liquid refrigerant in the condenser 41, and is turned on so that the solenoid valve SV is turned on.
2 to the drain pan heater 47.

As shown in FIG. 2, a plurality of cooling units No. 1 in the same freezer 15 are provided. When the 1 to 3 cooling units 11 to 13 are installed, the same control device normally switches between cooling and defrosting at the same time. No. 2 and No. 3 cooling units 12,
Also in No. 13, 1 Cooling unit 11 compressor M
Compressors MC11, MC21, fans MF11, MF2 similar to C1, fan MF1 and solenoid valves SV1, SV2
1 and solenoid valves SV11, SV21; SV12, SV2
2 is provided respectively, the operation shown in Table 2 below is preferable. Fan MF of outside unit 10
Since 2 is turned off and stopped, the heat of the hot gas discharged from the compressor MC2 can be effectively used as a defrosting auxiliary heat source of each cooling unit 11, 12, 13.

[0031]

[Table 2]

FIG. 3 shows the effect of using the cascade condenser 42 as an auxiliary heat source for the defrost in the embodiment shown in FIG. 3 (1) shows a state change when performing a simple hot gas defrost without using the cascade condenser 42 during defrosting, and FIG. 3 (2) shows a state change when a heat source is supplied through the cascade condenser 42. Indicates. That is, No. The compressor MC1 of the 1 cooling unit 11 moves from the state of A1, A2 to B1, B
Compress the refrigerant to the state of 2 and change from the state of C1 and C2 to D
In the simple hot gas defrost where the auxiliary heat source cannot be obtained when sucking the refrigerant up to the state of 1 and D2, B1 to C1
It can be seen that the enthalpy value decreases up to, while the enthalpy value increases from B2 to C2 if an auxiliary heat source is obtained.

FIG. 4 shows the expansion valve 28 and the temperature sensing tube 3 shown in FIG.
8 and the solenoid valve SV1, an electric valve 55, a temperature detector 56
a, 56b and the control device 57 are replaced. The opening degree of the motor-operated valve 55 can be adjusted from the fully closed state to the fully opened state by an input pulse signal. The temperature detectors 56a and 56b are realized by, for example, a thermistor, and generate an electric signal corresponding to the degree of superheat of the conduit 37. The control device 57 is realized by including a microcomputer and the like, and at the time of cooling, the superheat degree detected by subtracting the temperature detected by the temperature detector 56b from the temperature detected by the temperature detector 56a becomes constant at 5 ° C., for example. Adjust the opening of the motorized valve 55, and at the time of defrosting the motorized valve 55
Control the fully open state. That is, the expansion valve 28 and the solenoid valve SV1 or the motor-operated valve 55 constitutes the valve means of the present invention.

FIG. 5 shows the construction of one cooling unit according to another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 1, and the corresponding parts are designated by the same reference numerals.
It should be noted that the defrosting of the low temperature side refrigeration cycle is performed by the reverse cycle defrosting method using the four-way switching valve 60 which is the reverse cycle defrosting means. On the outlet side of the condenser 41 of the cascade condenser 42, a check valve 61 that blocks the flow of the refrigerant during the reverse cycle and a capillary 62 through which the refrigerant passes during the reverse cycle are connected in parallel, and further the expansion valve 43 and the cooling valve are connected. It is connected to the inlet side of the evaporator 45 via a parallel circuit of the check valve 63 that blocks the flow of the refrigerant during the normal cycle.

FIG. 6 shows the construction of a cooling unit according to still another embodiment of the present invention. The structure of the present embodiment is similar to the structure shown in FIG. 1, and corresponding parts are designated by the same reference numerals. It should be noted that the solenoid valve SV is connected in series with the expansion valve 28.
3 is provided, a defrost pipe line is provided from the upstream side to the fan guard heater 65 and the drain pan heater 47 via the solenoid valve SV2, and the return line is connected to the pipe line 37. When defrosting, solenoid valve SV
3 is closed when it is off, and solenoid valve SV2 is open when it is on. That is, the solenoid valves SV2 and SV3 form the switching means of the present invention. Further, a solenoid valve SV4 is provided in parallel with the expansion valve 43, and is closed by OFF during freezing and opened by ON during defrosting. During defrosting of the low temperature side refrigeration cycle, the hot gas from the compressor MC1 flows from the evaporator 41 of the cascade condenser 42 to the evaporator 45 via the solenoid valve SV4.
The hot gas defrosting is performed on the evaporator 45. The liquid refrigerant from the high temperature side refrigeration cycle is supplied to the fan guard heater 65 and the drain pan heater 47 via the solenoid valve SV2, and it is not necessary for the low temperature side refrigeration cycle to perform defrosting. Further, in the embodiment shown in FIGS. 1, 5 and 6, the cooling unit may be single.

Although the fan guard heater 65 and the drain pan heater 47 are connected in series in the embodiment of FIG. 6, they may be connected in parallel, or only one of them may be provided. Of course good things.

FIG. 7 shows the configuration of still another embodiment of the present invention. This embodiment is also similar to the embodiment shown in FIG. 1, and corresponding parts are designated by the same reference numerals. It should be noted that the No. connected to one outside unit 90 is the No. 1 cooling unit 91 and No. 1 cooling unit. 2 cooling units 9
2 is configured to obtain an auxiliary heat source by natural circulation during defrosting of either one. Compressors MC1 and M are provided in the cooling units 91 and 92, respectively.
C11, four-way switching valves 60, 70, evaporators 40, 80 and condensers 41, 81 including a cascade condenser 42,
82, parallel circuit of check valves 61, 71 and capillaries 62, 72, parallel circuit of expansion valves 43, 74 and check valves 63, 73, evaporators 45, 75, temperature sensitive tubes 44, 76, accumulators 46, 77. , Fans MF1, MF11, solenoid valve SV
1, SV11, solenoid valves SV3, SV13, expansion valve 28,
83, the temperature-sensitive cylinders 38 and 88, and the conduits 37 and 87 are included.

The outside unit 90 includes a compressor MC2, a condenser 51, an accumulator 52, a low pressure expansion valve 53, a fan MF2, and solenoid valves SV5 and SV6 as opening / closing means. The solenoid valve SV5 is provided between the outlet side of the condenser 51 and the liquid pipeline 20. Solenoid valve SV6
Is provided between the gas pipeline 30 and the inlet side of the accumulator 52. The control states of the embodiment of FIG. 7 are shown in Table 3 below.

[0039]

[Table 3]

Attention should be paid to the solenoid valve SV during defrosting.
5 and SV6 are turned off and closed, and the liquid pipe line 20 and the gas pipe line 30 are used to enable natural circulation of the refrigerant. Natural circulation of the refrigerant occurs because the density of the refrigerant decreases as the temperature rises. Of course, the defrost in each cleaning unit 91, 92 may be the same as that in the embodiment shown in FIG.

[0041]

As described above, according to the present invention, the cascade condenser 4 can be operated during the defrosting of the low temperature side refrigeration cycle.
Since 2 serves as an auxiliary heat source for the hot gas, it is possible to quickly defrost the evaporator 45 via the hot gas flow means SV2 of the low temperature side refrigeration cycle.

Further, according to the present invention, the plurality of cooling units 11, 12, 13 use the liquid refrigerant supplied from the single outdoor unit 10 as an auxiliary heat source during defrosting,
A quick defrost can be done.

Further, in the present invention, all the cooling units 1
Since the fan MF2 in the outdoor unit 10 is stopped when 1, 12, 13 perform defrosting, the outdoor unit 1
The heat of the hot gas discharged from the compressor MC2 in 0 can be used more effectively.

Further, according to the present invention, the low temperature side refrigerating cycle is provided with the reverse cycle defrosting means 60 and 70, and the cascade condenser 42 serves as an auxiliary heat source to perform quick defrosting.

Further, according to the present invention, the evaporator 45 of the low temperature side refrigeration cycle is provided with the drain pan heater 47,
At the time of defrost, the liquid refrigerant from the condenser 51 of the high temperature side refrigeration cycle is supplied to serve as an auxiliary heat source. Since the heat source for defrosting is supplied to the drain pan heater 47 from the high temperature side refrigeration cycle, the low temperature side refrigeration cycle uses the evaporator 4
Only defrosting of 5 is required, and quick defrosting is possible.

According to the invention, a fan guard heater 65 is provided in the evaporator 45 of the low temperature side refrigeration cycle,
At the time of defrost, the liquid refrigerant is supplied from the high temperature side refrigeration cycle and serves as an auxiliary heat source. In the low temperature side refrigeration cycle, since only the evaporator 45 needs to be defrosted during defrosting, quick defrosting is possible.

Further, according to the present invention, the evaporator 45 of the low temperature side refrigeration cycle is provided with the drain pan heater 47 and the fan guard heater 65. The liquid refrigerant is supplied to the drain pan heater 47 and the fan guard heater 65 from the condenser 51 of the high temperature side refrigeration cycle at the time of defrosting to serve as an auxiliary heat source to perform defrosting. In the low temperature side refrigeration cycle, only the evaporator 45 needs to be defrosted, and quick defrosting is possible.

Further, according to the present invention, at the time of defrosting at least one of the plurality of low temperature side refrigeration cycles, the natural circulation of the refrigerant supplies the auxiliary heat source for defrosting from the cascade condenser during the refrigerating operation, which enables quick defrosting. Becomes

[Brief description of drawings]

FIG. 1 is a refrigerant piping system diagram of an embodiment of the present invention.

FIG. 2 is a device layout diagram of the embodiment shown in FIG.

FIG. 3 is a graph showing a state change during defrosting of the embodiment shown in FIG.

FIG. 4 is a partial piping system diagram showing another configuration of a part of the embodiment shown in FIG.

FIG. 5 is a piping system diagram of a cooling unit according to another embodiment of the present invention.

FIG. 6 is a piping system diagram of a cooling unit according to still another embodiment of the present invention.

FIG. 7 is a refrigerant piping system diagram of still another embodiment of the present invention.

[Explanation of symbols]

10 Chilled unit 11, 91 No. 1 cooling unit 12, 92 No. 2 Cooling unit 13 No. 3 Cooling Unit 20-23 Liquid Pipeline 28 Expansion Valve 30-33 Gas Pipeline 40,80 Evaporator 41,81 Condenser 42,82 Cascade Condenser 43,74 Expansion Valve 45,75 Evaporator 47 Drain Pan Heater 51 Condenser 55 Motorized valve 60, 70 Four-way switching valve 65 Fan guard heater MC1, MC2, MC11 Compressor MF1, MF2, MF11 Fan SV1, SV2, SV3, SV4, SV5, SV6, S
V11, SV13 solenoid valve

Claims (8)

[Claims] 1. A defrosting device of a binary refrigeration system, comprising a cascade condenser 42 for thermally coupling an evaporator 40 of a high temperature side refrigeration cycle and a condenser 41 of a low temperature side refrigeration cycle, wherein the low temperature side refrigeration cycle is a cascade condenser. Hot gas flow means SV2 for flowing hot gas during defrost from the outlet side of the condenser 41 to the inlet side of the evaporator 45.
The high temperature side refrigeration cycle has an expansion valve function between the outlet side of the condenser 51 and the inlet side of the evaporator 40 of the cascade condenser 42 during cooling of the low temperature side refrigeration cycle and opens during defrosting. Functional valve means 28, SV1; 5
5. A defrosting device for a dual refrigeration system, which is provided with 5. 2. A defrosting device of a binary refrigeration system comprising a cascade condenser 42 for thermally coupling an evaporator 40 of a high temperature side refrigeration cycle and a condenser 41 of a low temperature side refrigeration cycle, wherein the low temperature side refrigeration cycle is a cascade condenser. Hot gas flow means SV2 for flowing hot gas during defrost from the outlet side of the condenser 41 to the inlet side of the evaporator 45.
The high temperature side refrigeration cycle has an expansion valve function between the outlet side of the condenser 51 and the inlet side of the evaporator 40 of the cascade condenser 42 during cooling of the low temperature side refrigeration cycle and opens during defrosting. Functional valve means 28, SV1; 5
5, the compressor MC2 and the condenser 51 of the high temperature side refrigeration cycle
Is provided in a single unit 10 outside the refrigerator, and has the low temperature side refrigeration cycle, the valve means 28 of the high temperature side refrigeration cycle, SV1; 55, and the cascade condenser 42.
Is provided in each of the cooling units 11, 12, 13 of the plurality of cooling units 11, 12, 13, respectively. 3. The plurality of cooling units 11, 12, 1
3. The defrosting device for a dual refrigeration system according to claim 2, further comprising control means for stopping the fan MF2 that ventilates the condenser 51 when all three are defrosted. 4. A defrosting device of a binary refrigeration system comprising a cascade condenser 42 for thermally coupling an evaporator 40 of a high temperature side refrigeration cycle and a condenser 41 of a low temperature side refrigeration cycle, wherein the low temperature side refrigeration cycle is Reverse cycle defrost means 60 and 70 for switching the flow direction to the direction opposite to that during cooling during defrost are provided, and the high temperature side refrigeration cycle includes the outlet side of the condenser 51 and the inlet side of the evaporator 40 of the cascade condenser 42. In the meantime, the valve means 28, SV1; 5 having an expansion valve function during cooling of the low temperature side refrigeration cycle and having a valve opening function during defrosting.
5. A defrosting device for a dual refrigeration system, which is provided with 5. 5. A defrosting device for a dual refrigeration system, comprising a cascade condenser 42 for thermally coupling an evaporator 40 for a high temperature side refrigeration cycle and a condenser 41 for a low temperature side refrigeration cycle, wherein an evaporator 45 for a low temperature side refrigeration cycle is provided. The drain pan heater 47 is provided in the high temperature side refrigeration cycle, and the refrigerant from the outlet side of the condenser 51 is supplied to the inlet side of the evaporator 40 of the cascade condenser 42 via the expansion mechanism 28 during cooling of the low temperature side refrigerant cycle. Switching means SV2, S for guiding and guiding to the drain pan heater 47 of the low temperature side refrigeration cycle during defrosting
A defrosting device for a dual refrigeration system, characterized by comprising V3. 6. A defroster for a dual refrigeration system, comprising a cascade condenser 42 for thermally coupling an evaporator 40 for a high temperature side refrigeration cycle and a condenser 41 for a low temperature side refrigeration cycle, wherein an evaporator 45 for a low temperature side refrigeration cycle is provided. Fan MF that ventilates
1 is provided with a fan guard heater 65. In the high temperature side refrigeration cycle, the refrigerant from the outlet side of the condenser 51 is supplied to the inlet of the evaporator 40 of the cascade condenser 42 via the expansion mechanism 28 during cooling of the low temperature side refrigeration cycle. To the fan guard heater 65 of the low temperature side refrigeration cycle during defrosting.
A defrosting device for a binary refrigeration system, comprising a SV3. 7. A defroster for a dual refrigeration system, comprising a cascade condenser 42 for thermally coupling an evaporator 40 for a high temperature side refrigeration cycle and a condenser 41 for a low temperature side refrigeration cycle, wherein an evaporator 45 for a low temperature side refrigeration cycle is provided. The fan guard heater 65 is provided in the drain pan heater 47 and the fan MF1 that ventilates the evaporator 45. The high temperature side refrigeration cycle expands the refrigerant from the outlet side of the condenser 51 during cooling of the low temperature side refrigeration cycle. Switching mechanism SV2 and SV3 are provided to guide the gas to the inlet side of the evaporator 40 of the cascade condenser 42 via the mechanism 28 and switch to the drain pan heater 47 and the fan guard heater 65 of the low temperature side refrigeration cycle during defrosting. Defrosting device for dual refrigeration system. 8. A defrosting device for a dual refrigeration system, comprising a plurality of cascade condensers 42, 82 for thermally coupling an evaporator 40 of a high temperature side refrigeration cycle and a condenser 41 of a plurality of low temperature side refrigeration cycles, wherein: On the outlet side of the condenser 51 of the refrigeration cycle, there are provided opening / closing means SV5, SV6 which are opened during cooling of the low temperature side refrigeration cycle and closed during defrosting of the low temperature side refrigeration cycle. And the inlet sides of the evaporators 40, 80 of the plurality of cascade condensers 42, 82 have an expansion valve function during cooling of each low temperature side refrigeration cycle, and a valve opening function during defrosting of each low temperature side refrigeration cycle. A defrosting device for a binary refrigeration system, which is provided with valve means SV1, 28; SV11, 83, respectively.