JP2021096054A - Cooling device using air refrigerant cycle - Google Patents

Abstract

To provide a cooling device using an air refrigerant cycle that can maintain a stable cooling efficiency for a long term without being influenced by frost adhering to an inside of piping.SOLUTION: A cooling device 1 uses an air refrigerant cycle in which a compressor C for compressing air collected from a chamber to be cooled 2, heat exchangers 3, 4 for cooling the air compressed by the compressor C, and an expander E for expanding the air cooled by the heat exchangers 3, 4 are connected by pipes 7a-7 m. The cooling device is provided with jet flow generating parts 23, 24, 7d, 5 for jetting compressed air toward the inside of a piping member 22 which is located downstream of the expander E.SELECTED DRAWING: Figure 2

Description

The present invention relates to a cooling device using an air refrigerant cycle.

Cooling devices applied to cooled chambers such as warehouses for storing various materials, processed products, fresh foods, and the like are widely known. In such a cooling device, a refrigerant such as chlorofluorocarbon has been conventionally used, but in recent years, a cooling device using an air refrigerant has been required from the viewpoint of environmental protection.

As a cooling device using an air refrigerant, for example, as shown in Patent Document 1, a compressor that compresses the air taken into the piping path from the cooled chamber and a high-pressure high-temperature air compressed by the compressor are cooled. It is equipped with a heat exchanger and an expander that expands the high-pressure and low-temperature air cooled by the heat exchanger to a low pressure (approximately 1 atm), and ultra-low temperature air expanded by the expander is introduced from the piping path to the cooled chamber. There is a cooling device using an open air refrigerant cycle that supplies to.

In a cooling device using such an open air refrigerant cycle, the outside air (air) flowing in from the inlet / outlet of the cooled chamber or the exhaled breath of a worker working in the cooled chamber may be mixed. Since the amount of water contained in the air inside the cooling device changes due to these outside air and exhaled air, the water in the air solidifies in the piping path of the cooling device, especially on the downstream side of the inflator with a low temperature, and frost is formed. , This frost-rich ultra-low temperature air was sometimes blown into the cooled chamber. Therefore, the cooling device of Patent Document 1 is provided with a defroster for collecting moisture contained in ultra-low temperature air between the expander and the cooled chamber.

International Publication No. 2006/011297 (Page 7, Fig. 1)

The cooling device of Patent Document 1 collects coagulated or sublimated water, that is, frost, which accompanies the air circulating and moving in the air refrigerant cycle, by a defroster. However, on the downstream side of the expander where the moisture in the air tends to solidify in the piping path of this cooling device, frost does not flow in the cycle and stays on the wall surface on the downstream side of the expander, so it is removed. It could not be repaired with a froster. The accumulated frost increases over time, obstructing the air flow path in the air refrigerant cycle, causing turbulence in the flow field of the blown air, and operating control of the magnetic bearings that support the rotating shaft of the expander. There was a problem of affecting the.

The present invention has been made by paying attention to such a problem, and provides an air refrigerant cycle capable of maintaining stable control of cooling operation for a long period of time without being affected by frost adhering to the inside of the pipe. It is an object of the present invention to provide the cooling device used.

In order to solve the above problems, the cooling device using the air-refrigerant cycle of the present invention can be used.
A compressor that compresses the air recovered from the cooled chamber, a heat exchanger that cools the air compressed by the compressor, and an expander that expands the air cooled by the heat exchanger are connected by pipes. It is a cooling device that uses an air refrigerant cycle.
It is characterized in that a jet flow generating portion for ejecting compressed air toward the inside of the piping member on the downstream side of the expander is provided.
According to this feature, the frost adhering to the inside of the piping member on the downstream side of the expander, which is in a low temperature environment in the air refrigerant cycle, can be separated by the compressed air ejected toward the inside, so that the cooling operation can be performed. Can maintain control of. Further, by mixing the jet air with the air refrigerant and cooling it, it can be used as a part of the air refrigerant.

The compressed air is characterized in that it is air compressed by the compressor.
According to this feature, compressed air generated by the compressor of the air refrigerant cycle can be utilized.

The jet generating portion is characterized by having a communicating portion that bypasses the upstream side of the expander and the downstream side of the expander.
According to this feature, the high-pressure compressed air on the upstream side of the expander can be led out to the downstream side via the communication portion and used as jet air.

The jet generating portion is characterized by having an on-off valve that opens and closes the communicating portion.
According to this feature, the jet air can be easily ejected by intermittently opening the on-off valve, and the cooling efficiency of the air refrigerant can be maintained by always closing the on-off valve.

The jet generating portion is characterized by having a plurality of jet holes formed in the inner wall of the piping member.
According to this feature, the jet air ejected from the plurality of jet holes formed on the inner wall of the piping member easily removes the frost adhering to the inner wall.

The outer wall of the piping member is provided with an outer fitting member for outerly fitting the plurality of jet holes.
According to this feature, since a plurality of jet holes can be communicated with each other through the inside of the outer fitting member, jet air having substantially the same pressure can be ejected from these jet holes.

It is characterized in that a defroster is provided on the downstream side of the piping member.
According to this feature, the frost separated inside the piping member by the jet generating portion can be collected by the defroster on the downstream side of the piping member.

It is a figure which shows the cooling state of the cooling apparatus using the air-refrigerant cycle in the Example of this invention. (A) is a cross-sectional view showing an internal structure of an expansion turbine, and (b) is a view taken along the arrow A of (a). (A) is a schematic cross-sectional view in a plan view showing a defroster, and (b) is a schematic cross-sectional view in a side view showing a defroster. It is a figure which shows the defrost state of the cooling apparatus using an air-refrigerant cycle. It is a figure which shows another form of the cooling apparatus using an air-refrigerant cycle. It is sectional drawing which shows the internal structure of the expansion turbine in the modification.

A mode for carrying out the cooling device using the air-refrigerant cycle according to the present invention will be described below based on examples.

The cooling device using the air-refrigerant cycle according to the embodiment will be described with reference to FIGS. 1 to 6. First, reference numeral 1 in FIG. 1 is a cooling device using the air-refrigerant cycle to which the present invention is applied.

As shown in FIG. 1, the cooling device 1 in this embodiment is a piping system connected to a cooled chamber 2 which is a space for storing various materials, processed products, and objects to be cooled such as fresh foods. is there. The cooling device 1 is a cooling device using an air refrigerant cycle that sucks air from the cooled chamber 2, cools the air in the cooling device 1, and then returns the air to the cooled chamber 2.

More specifically, since the cooled chamber 2 has an entrance / exit that allows workers to enter and exit from the outside, the outside air (atmosphere) flowing in from the entrance / exit or the cooled chamber is used in the cooled chamber 2. The exhaled air of the worker is inevitably mixed. That is, it is a cooling device using a so-called open air refrigerant cycle in which the amount of water contained in the air taken into the cooling device 1 changes. The cooling device 1 can be applied to refrigeration, refrigeration, air-conditioning cooling, etc. depending on the difference in temperature and pressure of the system, and more preferably to a refrigeration system in an ultra-low temperature range of −55 ° C. or lower.

Next, the structure of the cooling device 1 will be described. The cooling device 1 mainly includes a compressor C (compressor), a first heat exchanger 3, a second heat exchanger 4, an expansion turbine E (expansion machine), and a defroster 6, and these devices will be described later. It is connected to the air via piping and valves so that it can be communicated with.

Specifically, the high temperature side pipe 3a of the first heat exchanger 3 is connected to the downstream side of the compressor C via the pipe 7a. The high temperature side pipe 4a of the second heat exchanger 4 is connected to the downstream side of the high temperature side pipe 3a of the first heat exchanger 3 via the pipe 7b, and the high temperature side pipe 4a of the second heat exchanger 4 The expansion turbine E is connected to the downstream side of the expansion turbine E via the pipe 7c, and the defroster 6 is connected to the downstream side of the expansion turbine E via the pipe 7e. Further, a communication pipe 7d as a communication passage that bypasses the expansion turbine E is provided between the pipe 7c on the upstream side of the expansion turbine E and the pipe 7e on the downstream side of the expansion turbine E. ..

An inlet valve 8 (switching means) is connected to the downstream side of the defroster 6 via a pipe 7f, and the downstream side of the inlet valve 8 is not shown in the cooled chamber 2 via the pipe 7h. It is connected to the vent of. An outlet valve 9 (switching means), which is a three-way switching valve, is connected to the other vent not shown in the cooled chamber 2 via a pipe 7j, and a pipe 7k is connected to the downstream side of the outlet valve 9. The low temperature side pipe 4b of the second heat exchanger 4 is connected via the pipe 7, and is connected to the compressor C via the pipe 7 m on the downstream side of the low temperature side pipe 4b of the second heat exchanger 4. Further, the pipe 7f has a branching bypass pipe 7n, and the bypass pipe 7n is connected to the outlet valve 9.

The compressor C and the expansion turbine E are driven by the motor 10. The motor 10 includes a pair of drive shafts 10a and 10b that are supported in a non-contact state by magnetic bearings and extend coaxially, and a compressor C and an expansion turbine E are connected to each of the motors 10 on the upstream side of the expansion turbine E. The rotational power of the expansion turbine E generated by the high-pressure air is transmitted to the drive shaft 10a of the compressor C via the drive shaft 10b, so that the power can be recovered.

Further, the motor 10 is connected to an air cooling circulation flow path 12 in which air is circulated by an air cooling fan 12a, and is cooled by the fan 12a and the air cooling circulation flow path 12. Further, a radiator 13 that exchanges heat with the air in the air-cooling circulation flow path 12 is connected to the air-cooling circulation flow path 12.

The first heat exchanger 3 is a water-cooled heat exchanger in this embodiment, and is a separate system from the high-temperature side pipe 3a in which air flows from the compressor C to the second heat exchanger 4 and the high-temperature side pipe 3a. It is equipped with a low temperature side pipe 3b through which cooling water circulates, and by exchanging heat between the high temperature side pipe 3a and the low temperature side pipe 3b, the air flowing in the high temperature side pipe 3a can be cooled. ing. The high temperature side pipe 3a and the low temperature side pipe 3b referred to here are the high temperature side and the low temperature side when the air flowing inside the two pipes for heat exchange in the first heat exchanger 3 is compared.

The second heat exchanger 4 includes a high temperature side pipe 4a through which air cooled by the first heat exchanger 3 flows, and a low temperature side pipe 4b through which air flows from the cooled chamber 2 to the compressor C. By exchanging heat between the side pipe 4a and the low temperature side pipe 4b, the air flowing through the high temperature side pipe 4a can be cooled. The high temperature side pipe 4a and the low temperature side pipe 4b referred to here are the high temperature side and the low temperature side when the air flowing inside the two pipes for heat exchange in the second heat exchanger 4 is compared.

As shown in FIGS. 2A and 2B, the expansion turbine E has a turbine blade 21 for rotationally driving the drive shaft 10b and the turbine blade 21 fitted outside in a sealed shape to rotate the turbine blade 21. The tubular member 22 is mainly composed of a tubular member 22 that sequentially leads out the air to be sent out to the downstream side. The tubular member 22 has a substantially truncated cone-shaped pipe wall 22b whose diameter is gradually increased toward the downstream side, and is configured so that air flows while expanding inside the pipe wall 22b. The large-diameter flange 22a located on the downstream side of the pipe 7e is connected to the pipe 7e.

Further, in the tube wall 22b having a substantially truncated cone shape of the tubular member 22, through holes 23 as small-diameter ejection holes penetrating the inside and outside of the tube wall 22b in the radial direction are evenly distributed along the circumferential direction. In this embodiment, a plurality of cells are formed in three rows along the air flow direction, that is, the axial direction. The arrangement of the through holes 23 is not limited to this embodiment, and may be arranged spirally apart, for example.

Further, in the pipe wall 22b of the tubular member 22, the tubular outer fitting member 24, which fits the plurality of through holes 23 together, forms a gap between the pipe wall 22b and the outer surface of the pipe wall 22b to form a sealed shape. It is attached to. The outer fitting member 24 is divided in the circumferential direction, and an annular seal member 25 is provided on the inner peripheral portions at both ends in the axial direction.

Further, the pipe wall of the outer fitting member 24 is formed with a communication hole 24a that communicates with the inside and outside of the pipe wall, and one end side of the communication pipe 7d that communicates with the communication hole 24a is connected in a sealed manner. An on-off valve 5 that can open and close the inside of the communication pipe 7d is interposed, and as shown in FIG. 1, the other end side of the communication pipe 7d is a pipe on the upstream side of the expansion turbine E. It is connected to 7c. That is, the communication pipe 7d functions as a bypass pipe that sends the compressed air on the upstream side of the expansion turbine E to the downstream side without passing through the expansion turbine E.

The plurality of through holes 23, the outer fitting member 24, the communication pipe 7d, and the on-off valve 5 formed in the tubular member 22 as described above constitute a jet generation portion according to the present invention.

Next, as shown in FIGS. 3A and 3B, the defroster 6 is provided on the downstream side of the jet generation portion described above, and is a box-shaped case connecting the pipe 7e and the pipe 7f. It is composed of 6a and a mesh member 6b that divides the case 6a into a space on the pipe 7e side and a space on the pipe 7f side. As will be described later, when the air flowing from the expansion turbine E to the pipe 7f via the pipe 7e passes through the mesh member 6b, the moisture contained in the air is adsorbed on the mesh member 6b as frost. The frost captured by the defroster 6 in this embodiment is not limited to the one in which water vapor in the air is sublimated and solidified, but also includes an icy individual in which the moisture in the air is solidified.

Further, a detection means 14 for detecting clogging of the defroster 6 is provided around the defroster 6. The detection means 14 includes a pressure gauge 14a connected to the upstream side of the mesh member 6b of the defroster 6, a pressure gauge 14b connected to the downstream side of the mesh member 6b, and pressure gauges 14a and 14b. It is composed of a differential pressure gauge 14c that measures the differential pressure, and when the differential pressure measured by the differential pressure gauge 14c exceeds a predetermined threshold value, the defroster 6 detects that clogging has occurred. .. When the detecting means 14 detects the clogging of the defroster 6, the cooling device 1 is switched to a defrost operation for defrosting the defroster 6 and each pipe / device. The defrost operation will be described in detail later.

Further, the cooling device 1 has a control unit (not shown) that is electrically connected to the motor 10, the inlet valve 8, the outlet valve 9, the detection means 14, and the like described above, and the control unit is connected to the detection means 14. Based on the received information on the differential pressure of the defroster 6, the motor 10 is driven and the valve is opened and closed, and the cooling operation or the defrost operation can be switched and controlled.

Next, the operation when the cooling device 1 is in the cooling operation will be described with reference to FIG. In the following description, the internal air A1 (about 1 atm, about −55 ° C.) in the chamber 2 to be cooled is used as a reference, and the high pressure means that the temperature is higher than that of the internal air A1. The pressure means that the pressure is substantially the same as that of the air inside the refrigerator A1, the same temperature means that the temperature is within an error of 10 ° C. as compared with the air inside the refrigerator A1, and the high temperature and the low temperature mean the same temperature. It means that it is hotter and colder than.

During the cooling operation, the inlet valve 8 is opened, the pipe 7f on the downstream side of the defroster 6 is communicated with the cooled chamber 2, and the bypass pipe 7n side of the outlet valve 9 is closed, so that the cooled chamber 2 and the second 2 A circulation flow path for cooling operation is formed so as to communicate with the low temperature side pipe 4b of the heat exchanger 4.

As shown in FIG. 1, when the compressor C and the expansion turbine E are driven, the compressor C sucks and compresses the normal pressure high temperature air A1'in the pipe 7 m. The high-pressure high-temperature air A2 compressed by the compressor C is discharged to the high-temperature side pipe 3a of the first heat exchanger 3 through the pipe 7a.

During the cooling operation, the cooling water circulates in the low temperature side pipe 3b of the first heat exchanger 3, so that the high pressure high temperature air A2 discharged to the high temperature side pipe 3a of the first heat exchanger 3 is the first heat. The heat is exchanged with the cooling water of the low temperature side pipe 3b of the exchanger 3, and becomes high pressure high temperature air A3 of about 2 atm and about 45 ° C., which is discharged to the high temperature side pipe 4a of the second heat exchanger 4.

The high-pressure high-temperature air A3 discharged to the high-temperature side pipe 4a of the second heat exchanger 4 is sucked into the compressor C from the cooled chamber 2 via the low-temperature side pipe 4b of the second heat exchanger 4 (internal air A1 ( It exchanges heat with about 1 atm and about −55 ° C.) to become high-pressure same-temperature air A4, which is discharged to the expansion turbine E via the downstream pipe 7c. At this time, the high-pressure high-temperature air A3 is heat-exchanged with the internal air A1, so that a part of the moisture contained in the high-pressure high-temperature air A3 is formed on the inner peripheral surface of the high-temperature side pipe 4a of the second heat exchanger 4. Since it adheres as frost, the amount of water contained in the high-pressure co-temperature air A4 discharged to the downstream pipe 7c is reduced. On the other hand, the internal air A1 at about −55 ° C. is heat-exchanged with the high-pressure high-temperature air A3 to become normal-pressure high-temperature air A1 ′ and flows into the pipe 7 m.

The high-pressure co-temperature air A4 discharged to the expansion turbine E is expanded by the expansion turbine E to become normal-pressure low-temperature air A6, and a part of the moisture contained in the normal-pressure low-temperature air A6 becomes frost to form cold air. It is mixed, flows through the pipe 7e, and is discharged to the defroster 6.

Further, as shown in FIG. 2B, a part of the moisture contained in the normal pressure low temperature air A6 becomes frost F, and the inner surface 22c of the pipe wall 22b of the tubular member 22 constituting the expansion turbine E becomes. Adheres to. Here, by opening the on-off valve 5 interposed in the communication pipe 7d that bypasses the expansion turbine E, the high-pressure compressed air A5 that is branched from the high-pressure co-temperature air A4 on the upstream side of the expansion turbine E communicates. A plurality of through holes 23, which are introduced into the outer fitting member 24 via the pipe 7d and further formed through the pipe wall 22b of the tubular member 22, are vigorously ejected as jet air toward the inside of the tubular member 22. Will be done. By doing so, the frost F adhering to the inner surface 22c of the pipe wall 22b of the tubular member 22 can be peeled off.

In particular, since the through hole 23 penetrates the tube wall 22b of the tubular member 22 in a substantially orthogonal direction, that is, toward the downstream side, the frost adhering to the inner surface 22c around the through hole 23 can be easily peeled off. Further, the frost that has been peeled off in this way can be further peeled off in a wide range around the frost, that is, the frost in the vicinity of the through hole 23 adjacent to the through hole 23 described above.

The on-off valve 5 is controlled to open and close by a control unit connected to a control cable (not shown), is normally closed during normal operation, and is intermittently opened for a short time at predetermined time intervals. By doing so, most of the air refrigerant can pass through the expansion turbine E without bypassing the communication pipe 7d, so that the high drive efficiency of the drive shaft 10b can be maintained. The on-off valve 5 is not necessarily limited to one that opens and closes intermittently. For example, a sensor such as a pressure gauge is provided on the downstream side of the expansion turbine E, and the on-off valve 5 is opened when frost adhesion is detected by the sensor. It may be controlled to do so.

The jet air ejected from the through hole 23 described above will not only have the effect of removing the frost that has already adhered to the inner surface 22c of the pipe wall 22b of the tubular member 22 constituting the expansion turbine E, but will also adhere to the inner surface 22c. It also has the effect of blowing off the frost to be blown off by the jet air, that is, preventing the adhesion of frost. Further, as described above, since the frost generated on the pipe wall 22b of the tubular member 22 constituting the expansion turbine E is separated by the jet air, it is separated by the normal pressure low temperature air A6 on the downstream side of the expansion turbine E. There is a mixture of frost.

When the normal pressure low temperature air A6 discharged to the defroster 6 passes through the mesh member 6b of the defroster 6, the frost contained in the normal pressure low temperature air A6 adheres to the mesh member 6b, whereby the frost is attached to the mesh member 6b. The normal pressure low temperature air A7 has a smaller amount of water than the normal pressure low temperature air A6. The normal pressure low temperature air A7 is discharged to the cooled chamber 2 side via the pipe 7f. In this way, since the moisture such as frost contained in the normal pressure low temperature air A6 expanded by the expansion turbine E is removed by the defroster 6, it is possible to suppress the frost from blowing out into the cooled chamber 2.

The normal pressure low temperature air A7 discharged to the downstream side of the defroster 6 is discharged to the cooled chamber 2 via the inlet valve 8. The normal pressure low temperature air A7 discharged to the cooled chamber 2 becomes the internal air A1 at about −55 ° C. by mixing with the air or the like flowing from the outside of the cooled chamber 2.

As described above, according to the cooling device 1 using the air refrigerant cycle of the present invention, the jet flow generation unit that ejects compressed air toward the inside of the tubular member 22 which is a piping member on the downstream side of the expander E. The frost F adhering to the inside of the tubular member 22 which becomes a low temperature environment in the air-cooling cycle can be separated by the compressed air ejected toward the inside, which affects the magnetic bearing. The control of the cooling operation can be maintained without giving. Further, by mixing the jet air with the air refrigerant and cooling it, it can be used as a part of the air refrigerant.

Further, since the compressed air is the air compressed by the compressor C (compressor), the compressed air generated by the compressor C of the air refrigerant cycle can be used.

Further, the jet generation portion according to the present invention has a communication pipe 7d as a communication portion that bypasses the upstream side of the expansion turbine E (expansion machine) and the downstream side of the expansion turbine E, so that the expansion turbine E The high-pressure compressed air on the upstream side of the above can be led out to the downstream side via the communication pipe 7d and used as the jet air.

Further, since the jet generation unit has an on-off valve 5 for opening and closing the communication pipe 7d, the jet air can be easily ejected by intermittently opening the on-off valve 5, and the on-off valve is always open. By closing 5, the cooling efficiency of the air refrigerant can be maintained.

Further, the jet generation portion has through holes 23 as a plurality of jet holes formed in the inner wall of the tubular member 22, so that the through holes 23 formed in the inner wall of the tubular member 22 can be used. The jet air that erupts easily separates the frost F adhering to the inner wall.

Further, since the outer wall of the tubular member 22 is provided with the outer fitting member 24 for fitting the plurality of through holes 23 together, the plurality of through holes 23 are communicated with each other through the inside of the outer fitting member 24. Therefore, jet air having substantially the same pressure can be ejected from these through holes 23.

Further, since the defroster 6 is provided on the downstream side of the tubular member 22, the frost F peeled off inside the tubular member 22 by the jet generating portion is removed on the downstream side of the tubular member 22. It can be collected by the defroster 6 of.

Next, the defrost operation of the cooling device 1 will be described with reference to FIG. As described above, when the differential pressure gauge 14c detects that the differential pressure between the upstream side and the downstream side of the defroster 6 exceeds a predetermined threshold value during the cooling operation of the cooling device 1, the defrosting is performed. Assuming that the inside of the vessel 6 is clogged with frost above a certain level, the control unit (not shown) of the cooling device 1 switches to the defrost operation.

As shown in FIG. 4, during the defrost operation, the inlet valve 8 is closed to prevent the pipe 7f from communicating with the cooled chamber 2, and the bypass pipe 7n side of the outlet valve 9 is opened to open the bypass pipe 7n. Defrost operation in which the cooling chamber 2 and the low temperature side pipe 4b of the second heat exchanger 4 are not communicated with each other by communicating the pipe 7k with the pipe 7k and blocking the space between the pipe 7j and the pipe 7k of the outlet valve 9. A circulation flow path is formed.

The compressor C and the expansion turbine E during the defrost operation are driven by the motor 10 having a rotation speed lower than the rotation speed during the cooling operation (for example, about one-third). The compressor C sucks and compresses the air A11'in the pipe 7 m. The air A21 compressed by the compressor C has a lower temperature and a lower temperature than the low temperature side pipe 4b of the second heat exchanger 4 during the cooling operation, and passes through the pipe 7a to the high temperature of the first heat exchanger 3. It is discharged to the side pipe 3a.

During the defrost operation, the air A21 becomes the air A31 whose high temperature is maintained without heat exchange, and is discharged to the high temperature side pipe 4a of the second heat exchanger 4. The air A31 discharged to the high temperature side pipe 4a of the second heat exchanger 4 is heat exchanged with the low temperature side pipe 4b of the second heat exchanger 4 to become relatively high temperature air A41, which is discharged to the expansion turbine E. ..

Further, the on-off valve 5 may be opened during the defrost operation, and when it is opened, the air A51 obtained by branching a part of the air A41 is discharged to the communication pipe 7d. The air A41 and the air A51 can melt a small amount of frost F left on the inner wall of the tubular member 22.

The air A41 discharged to the expansion turbine E is expanded by the expansion turbine E to become air A61, and is discharged to the defroster 6. Since the rotation speed of the expansion turbine E is lower than the rotation speed during the cooling operation, the temperature of the air A61 expanded by the expansion turbine E is slightly lower than that during the cooling operation, that is, the temperature is relatively high. The air A61 can melt the frost left on the inner surface 22c of the tubular member 22 constituting the expansion turbine E.

During the defrost operation, a heater (not shown) with an electric heating unit connected to the defroster 6 operates, which makes it possible to melt the frost accumulated in the defroster 6. There is. The air A61 discharged to the defroster 6 mixes with the air in the defroster 6 heated by the heat generated from the heater to become air A71, and is discharged to the pipe 7f on the downstream side.

As shown in FIGS. 3A and 3B, the bottom surface 6c of the defroster 6 is formed in a mortar shape, and the bottom surface of the defroster 6 communicates with the outside. An openable / closable drain valve 6d is provided. According to this, the water generated by melting the frost of the defroster 6 by the heater can be discharged to the outside through the drain valve 6d.

Since the air A71 discharged to the pipe 7f on the downstream side of the defroster 6 is heated by the heat of the heater, a predetermined section (pipe 7c, expansion turbine E, pipe 7e,) downstream of the second heat exchanger 4 The temperature of the air flowing through the defroster 6 section) rises as it circulates in the above-mentioned path.

As described above, during the defrost operation, the rotation transfer speed of the expansion turbine E is low, cold air (internal air A1) does not enter from the cooled chamber 2, the heater operates, and the like. The temperature of the air in the cooling device 1 becomes higher than that in the cooling operation, and the frost in the cooling device 1 can be melted.

Further, during the defrost operation, the inlet valve 8 is closed so that the pipe 7g is not communicated with the cooled chamber 2, and the bypass pipe 7n side of the outlet valve 9 is opened so that the bypass pipe 7n and the pipe 7k are communicated with each other. At the same time, a circulation flow path for defrost operation is formed in which the cooling chamber 2 and the low temperature side pipe 4b of the second heat exchanger 4 are not communicated with each other by closing the space between the pipe 7j and the pipe 7k of the outlet valve 9. Will be done. That is, during the defrost operation, the air A71 warmed by the heat of the heater that warms the inside of the defroster 6 is discharged, so that the air A71 is discharged on the downstream side of the second heat exchanger 4, which is more likely to generate frost than other parts. The air flowing through the predetermined section (section of pipe 7c, expansion turbine E, pipe 7e, defroster 6, and pipe 7f) can be quickly warmed. Since the temperature inside the piping system has risen due to the above-mentioned defrosting operation, the piping 7f, the bypass pipe 7n, and the piping 7k are opened and the cooled chamber 2 side is closed after the defrosting operation is completed. It is preferable that the cooling operation is performed for a certain period of time until the temperature in the piping system drops, and after the elapse of a certain period of time, the cooled chamber 2 side is opened. By doing so, it is possible to prevent the temperature inside the cooled chamber 2 from rising.

As shown in FIG. 5, an auxiliary defroster 16 may be provided between the high temperature side pipe 4a of the second heat exchanger 4 and the expansion turbine E and the communication pipe 7d. According to this, the auxiliary defroster 16 can collect the moisture contained in the high-pressure co-temperature air A4 flowing from the high-temperature side pipe 4a to the expansion turbine E as frost, so that the normal pressure flowing from the expansion turbine E to the defroster 6 can be collected. The amount of water contained in the low temperature air A6 can be further reduced. Since the structure of the auxiliary defroster 16 is the same as that of the defroster 6 described above, the description thereof will be omitted.

Although examples of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these examples, and any changes or additions within the scope of the gist of the present invention are included in the present invention. Is done.

For example, in the above embodiment, as a jet hole for ejecting compressed air, a through hole 23 penetrating the pipe wall 22b of the tubular member 22 in the radial direction is formed, but the present invention is not limited to this, for example, deformation of the jet hole. As shown in FIG. 6, as an example, a jet nozzle 26 communicating with the inside of the outer fitting member 24 may be arranged on the inner surface 22c of the pipe wall 22b of the tubular member 22, and the jet outlet of the jet nozzle 26 may be arranged. The jet air may be ejected along the inner surface 22c or toward the inner surface 22c. In this case, in order not to disturb the flow field inside the tubular member 22, a flat shape is preferable so that the ejection nozzle 26 does not protrude as much as possible from the inner surface 22c of the pipe wall 22b.

1 Cooling device 2 Cooled chamber 3 1st heat exchanger 4 2nd heat exchanger 5 On-off valve (jet generator)
6 Defroster 7d Communication pipe (communication part, jet generation part)
8 Inlet valve 9 Outlet valve 10 Motors 10a, 10b Drive shaft 14 Detection means 21 Turbine blade 22 Cylindrical member (piping member)
22b Pipe wall 22c Inner surface 23 Through hole (jet hole, jet generating part)
24 Outer fitting member (jet generator)
26 Ejection Nozzle 27 Ejection C Compressor
E Expansion turbine (expansion machine)

Claims (7)

A compressor that compresses the air recovered from the cooled chamber, a heat exchanger that cools the air compressed by the compressor, and an expander that expands the air cooled by the heat exchanger are connected by pipes. It is a cooling device that uses an air refrigerant cycle.
A cooling device using an air-refrigerant cycle, characterized in that a jet flow generating portion for ejecting compressed air toward the inside of a piping member on the downstream side of the expander is provided. The cooling device using the air refrigerant cycle according to claim 1, wherein the compressed air is air compressed by the compressor. The cooling device using the air refrigerant cycle according to claim 2, wherein the jet generating portion has a communication portion that bypasses the upstream side of the expander and the downstream side of the expander. The cooling device using the air-refrigerant cycle according to claim 3, wherein the jet generating portion has an on-off valve for opening and closing the communicating portion. The cooling device using the air refrigerant cycle according to any one of claims 1 to 4, wherein the jet generating portion has a plurality of jet holes formed in the inner wall of the piping member. The cooling device using the air-refrigerant cycle according to claim 5, wherein an outer fitting member for outerly fitting the plurality of jet holes is provided on the outer wall of the piping member. The cooling device using the air-refrigerant cycle according to any one of claims 1 to 6, wherein a defroster is provided on the downstream side of the piping member.

Images