EP4585866A1

EP4585866A1 - Ultra low temperature refrigeration system

Info

Publication number: EP4585866A1
Application number: EP23862750.9A
Authority: EP
Inventors: Naoko Nakamura; Hidehiro Kitayama; Kouichi Tsubata; Mizuo Kudo; Hideyuki Hara
Original assignee: Mayekawa Manufacturing Co
Current assignee: Mayekawa Manufacturing Co
Priority date: 2022-09-05
Filing date: 2023-06-22
Publication date: 2025-07-16
Also published as: KR20250040725A; WO2024053205A1; JP2024035976A; CN119678001A

Abstract

[Problem] To provide an ultralow-temperature refrigeration system capable of discharging accumulated frost on a defroster in frost form.

[Solution]An ultralow-temperature refrigerationsystemlincludes an ultralow-temperature warehouse 10, an air-refrigerant refrigerator 30 that cools air inside the ultralow-temperature warehouse and supplies the cooled air into the ultralow-temperature warehouse, and a defroster 40 that is provided inside the ultralow-temperature warehouse and removes frost in the air supplied from the air-refrigerant refrigerator into the ultralow-temperature warehouse.

Description

TECHNICAL FIELD

The present invention relates to an ultralow-temperature refrigeration system.

BACKGROUND ART

Recently, at ultralow-temperature refrigerated warehouses, transition from a two-stage refrigerator using a Freon refrigerant to an air-refrigerant refrigerator has been made to achieve energy saving through Freon refrigerant reduction and fan power reduction by environment measures.
The air-refrigerant refrigerator employs an air cycle that sucks air in the warehouse, compresses the air, and returns the air cooled through adiabatic expansion to the warehouse. Accordingly, water contained in the air becomes frost and accumulates in the refrigerator and the warehouse, and thus defrosting needs to be periodically performed in the refrigerator and the warehouse.
In relation to this, for example, a configuration in which a cyclone defroster is installed at a prior stage of a warehouse in an air-refrigerant refrigerator is disclosed in JP 2006-234275 A below. With this configuration, frost contained in air cooled by the air-refrigerant refrigerator is separated by a cyclone and the amount of frost that enters inside the warehouse decreases. JP 11-132583 A discloses that defrosting is performed by a net (filter component).

SUMMARY OF INVENTION

Technical Problem

In a case where a filter disclosed in JP 11-132583 A is employed as the defroster in the above-described configuration of JP 2006-234275 A (the defroster is outside the warehouse), the defroster is installed outside the warehouse, and thus when ambient temperature is relatively high, frost melts and plate-shaped ice forms at the filter component, and as a result, the defroster potentially becomes blocked due to clogging and unable to defrost.
The present invention has been made to solve the above-described problem, and an object of the present invention is provide an ultralow-temperature refrigeration system capable of discharging accumulated frost on a defroster in frost form. Means for Solving Problem
An ultralow-temperature refrigeration system according to the present invention that achieves the above-described object includes an ultralow-temperature warehouse in which a cooling target object is cooled and stored; an air-refrigerant refrigerator that sucks and cools air inside the ultralow-temperature warehouse and supplies the cooled air into the ultralow-temperature warehouse; and a defroster that is provided inside the ultralow-temperature warehouse and removes frost in the air supplied from the air-refrigerant refrigerator to the ultralow-temperature warehouse.

Advantageous Effect of the Invention

According to the above-described ultralow-temperature refrigeration system, since the defroster is provided inside the ultralow-temperature warehouse, defrosting can be performed in a low-temperature atmosphere, and accumulated frost on the defroster can be discharged in frost form. Thus, it is possible to excellently prevent a situation in which frost melts and plate-shaped ice forms at the filter component, and as a result, the defroster becomes blocked due to clogging and unable to defrost.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a system diagram illustrating an ultralow-temperature refrigeration system according to an embodiment of the present invention.
Fig. 2 is a diagram illustrating a defroster of the ultralow-temperaturerefrigerationsystemaccordingtothepresent embodiment in a state in which frost adheres to a filter component.
Fig. 3 is a diagram illustrating the defroster of the ultralow-temperaturerefrigerationsystemaccordingtothepresent embodiment in a state in which frost adhering to the filter component has dropped due to its own weight.
Fig. 4 is a diagram illustrating a defroster according to a modification.
Fig. 5 is a system diagram illustrating an ultralow-temperature refrigeration system according to a modification.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will be described below with reference to Figs. 1 to 3. Note that any same element in description of the drawings is denoted by the same reference sign and duplicate description thereof is omitted. The dimensional ratios of the drawings are exaggerated for convenience of description and different from actual ratios in some cases.
Fig. 1 is a system diagram illustrating an ultralow-temperature refrigeration system 1 according to the embodiment of the present invention. Fig. 2 is a diagram illustrating a defroster 40 of the ultralow-temperature refrigeration system 1 according to the present embodiment in a state in which frost adheres to a filter component 42. Fig. 3 is a diagram illustrating the defroster 40 of the ultralow-temperature refrigeration system 1 according to the present embodiment in a state in which frost adhering to the filter component 42 has dropped due to own weight.
The ultralow-temperature refrigeration system 1 according to the present embodiment is used to cool, for example, a drug warehouse. Note that a cooling target is not limited to a drug warehouse but may be a food warehouse or the like. As illustrated in Fig. 1, the ultralow-temperature refrigeration system 1 according to the present embodiment includes an ultralow-temperature warehouse 10 in which a cooling target object is cooled and stored, a circulation path 20 that is connected to the ultralow-temperature warehouse 10 and through which air circulates, an air-refrigerant refrigerator 30 that supplies cooled air into the ultralow-temperature warehouse 10 by using air in the ultralow-temperature warehouse 10 as a refrigerant, and the defroster 40 that is provided in the ultralow-temperature warehouse 10 and removes frost in air supplied from the air-refrigerant refrigerator 30 into the ultralow-temperature warehouse 10.
Drugs are cooled and stored in the ultralow-temperature warehouse 10 as described above. An automatic conveyance device is used to perform unmanned conveyance of drugs into and out of the ultralow-temperature warehouse 10 where drugs are cooled and stored. The automatic conveyance device potentially does not normally operate when frost adheres to the automatic conveyance device, and thus frost adhering to cooled air returning into the ultralow-temperature warehouse 10 needs to be removed by the defroster 40 when the air-refrigerant refrigerator 30 is used.
A suction port (not illustrated) for air circulating through the circulation path 20 and a blowoff port (not illustrated) through which air cooled by the air-refrigerant refrigerator 30 is blown out are disposed inside the ultralow-temperature warehouse 10. The internal temperature of the ultralow-temperature warehouse 10 is not particularly limited but is equal to or lower than -50°C. Since the internal temperature of the ultralow-temperature warehouse 10 is such an ultralow temperature, frost can be prevented from melting at the defroster 40 and can be excellently discharged in frost form. Moreover, when the internal temperature of the ultralow-temperature warehouse 10 is equal to or lower than -50°C, frost adhering to the filter component 42 drops as the amount of the frost reaches a certain amount, and thus continuous operation can be performed by removing the frost.
When frost is generated in air, the temperature of air containing water decreases and water in an amount exceeding a saturated amount deposits. For example, in a case of an internal temperature of -20°C to -30°C, which is higher than the internal temperature of the ultralow-temperature warehouse 10 according to the present embodiment, water exists as supercooling droplets for a long time and is likely to form large crystals through flocculation and coupling before freezing. However, since the internal temperature of the ultralow-temperature warehouse 10 according to the present embodiment is equal to or lower than -50°C, supercooling is likely to be released and water deposits as ice before mass increases, and thus frost is generated in a small particle size. Moreover, as the internal temperature of the ultralow-temperature warehouse 10 decreases, absolute humidity decreases and the amount of depositing water for the same temperature difference decreases, and accordingly, relatively small frost is generated. Thus, frost adhering to the filter component 42 to be described later is in powder form and can be easily discharged from inside the defroster 40 with wind pressure as described later.
As illustrated in Fig. 1, the air-refrigerant refrigerator 30 includes a compressor 31, an expander 32, and a primary cooler 33. The compressor 31 and the expander 32 are integrated and connected to the same motor M. The air-refrigerant refrigerator 30 constitutes a reverse Brayton cycle.
The cycle of the air-refrigerant refrigerator 30 will be described below. Note that temperatures described below are exemplary and the present invention is not limited thereto.
First, air in the ultralow-temperature warehouse 10 (-60°C), which is sucked into the air-refrigerant refrigerator 30 is compressed and heated at the compressor 31 and becomes high-temperature and high-pressure air at 90°C. Then, the air at 90°C is cooled to 40°C at the primary cooler 33.
Subsequently, the air at 40°C is adiabatically expanded and cooled to -80°C at the expander 32, and the air is transferred into the ultralow-temperature warehouse 10.
The defroster 40 is provided in the ultralow-temperature warehouse 10 as illustrated in Fig. 1. For example, in a case where the defroster is disposed outside the warehouse, frost melts and plate-shaped ice forms at the filter component when ambient temperature is relatively high, and as a result, the defroster potentially becomes blocked due to clogging and unable to defrost. However, since the defroster 40 according to the present embodiment is disposed inside the ultralow-temperature warehouse 10, defrosting can be performed in a low-temperature atmosphere and accumulated frost on the defroster 40 can be discharged in frost form. Furthermore, for example, in a case where the defroster is disposed outside the warehouse, since frost melts and plate-shaped ice forms at the filter component when ambient temperature is relatively high, and as a result, the defroster potentially becomes blocked due to clogging and unable to defrost, it is needed to provide a heat protection facility, which potentially leads to increase in the size of the entire system. However, since the defroster 40 according to the present embodiment is disposed inside the ultralow-temperature warehouse 10, defrosting can be performed in a low-temperature atmosphere and the heat protection facility is unnecessary, which prevents increase in the size of the entire system.
One defroster 40 is provided in the present embodiment. The defroster 40 removes frost contained in air cooled to -80°C by the air-refrigerant refrigerator 30 when the air is transferred into the ultralow-temperature warehouse 10. The configuration of the defroster 40 will be described below but is exemplary, and thus is not particularly limited.
As illustrated in Figs. 2 and 3, the defroster 40 includes a housing 41, the filter component 42 provided in the housing 41, a first flow path 43 through which air, from which frost is separated, is circulated into the ultralow-temperature warehouse 10, a first valve 44 provided in the first flow path 43, a second flow path 45 through which frost passes when discharged from the housing 41, and a second valve 46 provided in the second flow path 45.
A suction port 41A through which air cooled at the air-refrigerant refrigerator 30 and containing frost is sucked is formed at the housing 41.
Frost contained in air sucked through the suction port 41A adheres to the filter component 42 and is separated from the air. In the present embodiment, the filter component 42 is disposed to extend horizontally as illustrated in Figs. 2 and 3. With this configuration, the filter component 42 can be provided across a broad range and thus frost can excellently adhere to the filter component 42.
The filter component 42 is configured to include numerous void spaces. Frost F adheres to the filter component 42 as illustrated in Fig. 2 when air containing the frost passes through the filter component 42. Air from which frost is separated moves upward through the filter component 42 and is transferred into the ultralow-temperature warehouse 10 through the first flow path 43 (refer to arrows in Fig. 2) in a case where the first valve 44 is opened. Accordingly, normal cooling operation is performed in the ultralow-temperature warehouse 10 in this case.
As normal cooling operation continues, frost F adhering to the filter component 42 drops onto the lower surface of the housing 41 due to its own weight as illustrated in Fig. 3 when its amount becomes equal to or larger than a predetermined amount. The dropped frost F accumulates on the lower surface in what is called a powder state. Note that the defroster 40 may further include a dropping component that assists dropping of frost adhering to the filter component 42 due to its own weight. The dropping component is not particularly limited and may be an ultrasonic vibrator or a blowoff component that blows shot air, but is preferably an ultrasonic vibrator from the viewpoint of preventing clogging of the filter component 42.
Moreover, to assist dropping of frost adhering to the filter component 42 due to its own weight, air flowmaybe inverted (downward in Fig. 2) to drop the frost adhering to the filter component 42.
Once a predetermined amount of frost F accumulates on the lower surface of the housing 41, frost F can be discharged through the second flow path 45 with wind pressure of air sucked through the suction port 41A in a state in which the first valve 44 is closed and the second valve 46 is opened as illustrated in Fig. 3. Accordingly, the first valve 44 and the second valve 46 function as a discharge component that externally discharges frost in frost form. Specifically, normal cooling operation is stopped and defrosting operation is performed in the ultralow-temperature warehouse 10 in this case. The second valve 46 is preferably disposed inside the ultralow-temperature warehouse 10. Frost potentially melts and forms ice in the second valve 46, for example, in a case where the second valve 46 is disposed outside the ultralow-temperature warehouse 10. In the present embodiment, the above-described ice formation can be prevented since the second valve 46 is disposed inside the ultralow-temperature warehouse 10.
Frost discharged to the outside of the defroster 40 is received by, for example, a drain pan, melted by a heater installed in the drain pan, hot air, or the like, and discharged as water to prevent resublimation and facilitate frost removal work.
For example, in a case where the defroster 40 is not provided inside the ultralow-temperature warehouse 10, frost adhering to the filter component 42 melts and ice is generated at the filter component 42 when ambient temperature is relatively high, and as a result, the defroster 40 potentially becomes blocked and unable to defrost.
However, since the defroster 40 is disposed inside the ultralow-temperature warehouse 10 in the ultralow-temperature refrigeration system 1 according to the present embodiment, defrosting can be performed in a low-temperature atmosphere and accumulated frost on the defroster 40 can be discharged in frost form.
Note that a heater component may be attached to the filter component 42 of the defroster 40. With this configuration, even when frost adhering to the filter component 42 melts andplate-shaped ice forms at the filter component 42, the ice can be melted by the heater component and thus the defroster 40 can be prevented from becoming blocked and unable to defrost.
A defrosting method for the defroster 40 of the ultralow-temperature refrigeration system 1 according to the present embodiment will be described below. The defrosting method includes a suction step of sucking air with adhered frost the suction port 41A of the housing 41; a separation step of causing adhesion of the frost to the filter component 42 and separating the frost from the air; a step of transferring the air, from which the frost is separated by the filter component 42, into the ultralow-temperature warehouse 10; and a discharge step of externally discharging the frost having adhered to the filter component 42 and then dropped due to its own weight in frost form. In the discharge step, the frost is discharged through the second flow path 45 with wind pressure of the air sucked through the suction port 41A in a state in which the first valve 44 is closed and the second valve 46 is opened.
As described above, the ultralow-temperature refrigeration system 1 according to the present embodiment includes the ultralow-temperature warehouse 10 in which a cooling target object is cooled and stored, the air-refrigerant refrigerator 30 that sucks and cools air inside the ultralow-temperature warehouse 10 and supplies the cooled air into the ultralow-temperature warehouse 10, and the defroster 40 that is provided inside the ultralow-temperature warehouse 10 and removes frost in the air supplied from the air-refrigerant refrigerator 30 into the ultralow-temperature warehouse 10. According to the ultralow-temperaturerefrigerationsysteml thus configured, since the defroster 40 is provided inside the ultralow-temperature warehouse 10, defrosting can be performed in a low-temperature atmosphere and accumulated frost on the defroster 40 can be discharged in frost form. Thus, it is possible to excellently prevent a situation in which frost melts and ice is generated, and as a result, the defroster 40 becomes blocked and unable to defrost.
The defroster 40 includes the suction port 41A through which air with adhered frost is sucked, the filter component 42 to which the frost adheres and separates the frost from the air, the first flow path 43 through which the air, from which the frost is separated by the filter component 42, is transferred into the ultralow-temperature warehouse 10, and the discharge component that externally discharges the frost having adhered to the filter component 42 and then dropped due to its own weight in frost form. According to the ultralow-temperature refrigeration system 1 thus configured, it is possible to perform unmanned automatic defrosting since the discharge component is provided.
The ultralow-temperature warehouse 10 has an internal temperature equal to or lower than -50°C. According to the ultralow-temperature refrigeration system 1 thus configured, it is possible to prevent frost from melting at the defroster 40 and excellently discharge the frost in frost form since the internal temperature of the ultralow-temperature warehouse 10 is ultralow temperature.
Although the present invention is described above with reference to the embodiment, the present invention is not limited to the above-described embodiment and modifications but may be modified in various manners in the scope of the claims.
For example, the filter component 42 is disposed to extend horizontally as illustrated in Figs. 2 and 3 in the above-described embodiment. However, a filter component 142 may be disposed to extend vertically as illustrated in Fig. 4. With this configuration, the filter component 142 is disposed in a direction orthogonal to the traveling direction of air, and thus it is possible to efficiently cause adhesion of frost to the filter component 142. The number of filter components 42 and 142 provided is optional in any of the horizontal and vertical directions and is not limited to one.
One air-refrigerant refrigerator 30 and one defroster 40 are provided in the above-described embodiment. However, a plurality (three in Fig. 4) of air-refrigerant refrigerators 30 and defrosters 40 may be provided as illustrated in Fig. 4. In this case, when one of the three defrosters 40 performs defrosting operation, the other defrosters stop defrosting operation (performs normal operation), or when the other defrosters perform defrosting operation, the one defroster stops defrosting operation (performs normal operation). With this configuration, it is possible to continuously cool inside the ultralow-temperature warehouse 10 while excellently defrosting the defroster 40.
The discharge component is constituted by the first valve 44 and the second valve 46 in the above-described embodiment. However, the discharge component may be a conveyance device such as a conveyer disposed on the lower surface of the defroster 40 so that frost is discharged to the outside of the housing 41 by the conveyance device once a predetermined amount of frost accumulates on the conveyance device.
The present application is based on Japanese Patent Application No. 2022-140644 filed on September 5, 2022 , and the entire contents of which are incorporated herein by reference.

Reference Signs List

1: ultralow-temperature refrigeration system
10: ultralow-temperature warehouse
20: circulation path
30: air-refrigerant refrigerator
31: compressor
32: expander
33: primary cooler
40: defroster
41A: suction port
42, 142: filter component
43: first flow path
44: first valve
45: second flow path
46: second valve

Claims

An ultralow-temperature refrigeration system comprising:
an ultralow-temperature warehouse in which a cooling target object is cooled and stored;

an air-refrigerant refrigerator that sucks and cools air inside the ultralow-temperature warehouse and supplies the cooled air into the ultralow-temperature warehouse; and

a defroster that is provided inside the ultralow-temperature warehouse and removes frost in the air supplied from the air-refrigerant refrigerator to the ultralow-temperature warehouse.
The ultralow-temperature refrigeration system according to claim 1, wherein
a plurality of the defrosters are provided,

when one of the defrosters performs defrosting operation, the other defrosters stop defrosting operation, and

when the other defrosters perform defrosting operation, the one defroster stops defrosting operation.
The ultralow-temperature refrigeration system according to claim 1 or 2, wherein the defroster includes
a suction port through which the air with the adhered frost is sucked,

a filter component to which the frost adheres and that separates the frost from the air,

a first flow path through which the air, from which the frost is separated by the filter component, is transferred into the ultralow-temperature warehouse, and

a discharge component that externally discharges the frost having adhered to the filter component and then dropped due to its own weight in frost form.
The ultralow-temperature refrigeration system according to claim 1 or 2, wherein the ultralow-temperature warehouse has an internal temperature equal to or lower than -50°C.