JPH11132582A - Air refrigerant type refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the efficiency of a refrigerator from lowering due to moisture and floating substance mixed into the air while purifying the air when the air from a chamber required to be cooled is taken, as refrigerant, into an air refrigerant type refrigerator and the chamber is cooled by blowing cooled air directly from the refrigerator. SOLUTION: The air refrigerant type refrigerator comprises a compressor 7, an air cooler 8, an air to air heat exchanger 9 and an expansion unit 10 arranged in an air passage and the air in a chamber B required to be cooled is taken into a compressor 7 through the heat exchanger 9 before being blown into the chamber B from the expansion unit 10. The refrigerator further comprises a first bypath 13 provided with a valve for returning the air from the expansion unit 10 partially or entirely back to the heat exchanger 9 while bypassing the chamber B, a hot air bypath 14 provided with a valve for taking in the air of 0 deg.C or above from the air passage between the compressor and the expansion unit and supplying the air to the inlet side of the heat exchanger 9, or a hot air bypath for taking in high temperature compressed air from the air passage between the compressor and the expansion unit before entering into the air cooler 8 or the air heat exchanger 9 and supplying the air to the air passage on the inlet side of the expansion unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for an air-cooled refrigerator in which air in a cooling room is taken in as a refrigerant, and the refrigerant air cooled by the refrigerator is blown directly into the cooling room. The present invention relates to an air-refrigerant refrigeration system that prevents moisture and suspended substances mixed in refrigerant air from lowering the operation efficiency of the refrigeration system and simultaneously purifies air when cooling.

[0002]

2. Description of the Related Art A so-called air-refrigerant refrigerator in which high-pressure and high-temperature air is compressed by a compressor, cooled by a cooler, and then reduced by an expander to low pressure and low temperature does not use a refrigerant such as chlorofluorocarbon or ammonia. Does not adversely affect the environment. However, the efficiency is lower than that of a phase change type refrigeration cycle in which condensation and evaporation are performed using a refrigerant such as chlorofluorocarbon, and a large-scale apparatus is required to increase the efficiency. For this reason, various technological developments are being promoted with the aim of increasing the efficiency.

The present inventors have also disclosed, for example, Patent Publication No. 25
46765 and JP-A-9-210484 have proposed various air-cooled refrigerators (ice making devices) that can be put to practical use.

[0004]

There is nothing special in forming a so-called closed cycle in which low-temperature air produced by an air-refrigerant refrigerator is passed through a heat exchanger and returned to the refrigerator again. As long as outside air or contaminated air does not naturally enter the air path circulating as a refrigerant. However, in the case of forming a closed cycle with such an air-cooled refrigerator, efficiency is further reduced because heat is exchanged indirectly using a heat exchanger, and its use is also limited. Will be done.

On the other hand, the direct cooling system in which the refrigerant air of the air-refrigerant refrigerator is directly blown into a space for various uses to cool the space is directly cooled by room air. There is an advantage that is not provided in the above, and such a direct cooling system of air cannot be achieved by using other refrigerants such as Freon. For example, if a system that directly blows out the refrigerant air is used to cool a freezer for freezing and preserving foods, a freezer truck, a freezing container, food display shelves, and other various application spaces requiring cooling (called cooling rooms). Therefore, the features of the air-cooled refrigerator can be fully exhibited.

However, when the air-refrigerant refrigerator is operated in an open cycle, the general air is adiabatically expanded by the expander, so that the moisture in the air changes into fine ice chips. However, there is a problem in that this deposits and grows in the pipe of the low-temperature air pipe to increase the pressure loss, and in some cases, the pipe becomes blocked, leading to a freezing trouble.

In such an open cycle,
Not only the moisture in the air in the cooling chamber, but also dust, microorganisms, and contaminants floating in the air are directly entrained in the refrigerant air. And further promotes the formation of snow.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problem in the case where air in a cooling required chamber into which outside air or ambient air is mixed is introduced as a refrigerant into an air-refrigerant refrigerator.

[0009]

According to the present invention, a compressor, an air cooler, an air-to-air heat exchanger, and an expander are arranged in the air path in the order of the flow of air, and the air in the cooling required room is arranged. Into the compressor via the air-to-air heat exchanger,
In an air-refrigerant refrigeration system in which air exiting from the expander is blown into the cooling-required chamber, part or all of the air exiting the expander bypasses the cooling-required chamber to exchange air-to-air heat. Air at 0 ° C. or higher is taken in from a first bypass passage of a valve interposition for returning to the heat exchanger and an air passage before exiting the compressor and entering the expander, and the air is introduced into the air to the inlet side air of the air heat exchanger. Provided is an air-refrigerant refrigeration apparatus characterized in that a hot-air bypass path provided with a valve interposed for supplying to a path is provided.

Further, according to the present invention, a compressor, an air cooler, an air-to-air heat exchanger, and an expander are arranged in the air path in the order of the flow of air, and the air in the cooling required room is supplied to the air. In an air-refrigerant refrigeration system which takes in the compressor through an air heat exchanger and blows out the air exiting the expander into the required cooling chamber, part or all of the air exiting the expander is removed. A first bypass passage of a valve interposition for bypassing the cooling chamber and returning to the air-to-air heat exchanger; and an air cooler or an air passage of an air passage before exiting the compressor and entering the expander. Take hot compressed air from the air passage before entering the air heat exchanger,
There is provided an air-refrigerant refrigeration apparatus characterized in that a hot-air bypass path provided with a valve is provided to supply this to an inlet-side air path of an expander.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of equipment arrangement of an air-refrigerant refrigeration system according to the present invention. This shows the cooling chamber B on the load side. The cooling room B is, for example, a freezer and has doors for workers and foods, so that air inevitably flows in and out of the surrounding atmosphere. The equipment group of the refrigerator can be a device housed in one casing, and if this is an air-refrigerant refrigerator A, by connecting the refrigerator A and the cooling required room B by an air path, The air refrigerant refrigeration apparatus of the present invention is configured.

That is, the air inlet 1 of the air-refrigerant refrigerator A and the air outlet 2 of the cooling required room B are connected by the air passage 3,
Low temperature air discharge port 4a or 4b of refrigerator A and cooling room B required
The air outlet 5 is connected to an air passage 6 to take in the air in the cooling chamber B as a refrigerant for the refrigerator A, and to blow out the low-temperature air discharged from the refrigerator A to the cooling chamber B. The device is configured.

The air-refrigerant refrigerator A includes an air compressor 7, an air cooler 8, an air-to-air heat exchanger 9, and an air expander 1.
0 are arranged in the order of the flow of air, and the air taken in from the cooling chamber B in the air-to-air heat exchanger 9 exchanges heat with the air on the outlet side of the compressor. The air compressor is composed of two units, a main compressor 7 and an auxiliary compressor 11, and the air compressed by the auxiliary compressor 11 is cooled by an auxiliary cooler 12, and is taken into the main compressor 7. The compressor is a turbo type and the expander is a turbine type. Both are connected so that power is transmitted to each other, and the rotational power of the expander is transmitted to the rotary shaft of the compressor. Power recovery is performed.

As the air cooler 8 and the auxiliary cooler 12, a water-to-air heat exchanger (fin tube plate type heat exchanger) is used, and cooling water is passed through the plates. The air-to-air heat exchanger 9 forms an independent two-system air passage composed of a large number of narrow tube passages by laminating a large number of resin corrugated sheets. The air of one system and the air of the other system are separated. A resin corrugated plate is used as a heat exchange surface for indirect heat exchange.

As an example of a change in the state of air in the air-refrigerant type refrigeration apparatus, assuming that normal pressure air of -5 ° C. is taken into the refrigerator A from the cooling required chamber B, about 50 centimeters of air will About 1.4 atm at ℃, 4 with auxiliary cooler 12
At 0 ° C., the air becomes 1.4 atm, which is further compressed by the main compressor 7 to become high-temperature compressed air at about 100 ° C. and about 2 atm. The hot compressed air is cooled to about 40 ° C. in the air cooler 8 and to about 0 ° C. in the air-to-air heat exchanger 9 (the pressure is about 2 atm). The air at 2 ° C. and at 0 ° C. is expanded by the expander 10 to near normal pressure, and is cooled to around −20 ° C. with this expansion. The air at −5 ° C. (normal pressure) in the cooling required room B rises to about 35 ° C. at the normal pressure when passing through the air-to-air heat exchanger 9.

In this manner, the air in the cooling required room B (−5)
(° C., normal pressure) passes through the air-refrigerant refrigeration system A to become low-temperature air (−20 ° C., normal pressure). Maintain B at the required low temperature as a freezer.

In the present invention, in the air-refrigerant refrigeration system configured as described above, a part or all of the air that has exited the expander 10 is bypassed to the cooling-requiring chamber B and the air-to-air heat exchanger. First bypass 13 with valve intervention to return to 9
And a valve via which air of 0 ° C. or higher is taken in from an air passage after leaving the compressor 11 or 7 and before entering the expander 10 and supplied to the air passage on the inlet side of the air-to-air heat exchanger 9. A warm air bypass path 14 is provided.

In the example of FIG. 1, the first bypass passage 13 is provided so as to connect the point a of the air passage 6 and the point b of the air passage 3, and a valve 15 is interposed in the bypass passage 13. is there. The bypass valve 15 has a damper structure for opening and closing the air passage, and its opening degree can be adjusted. A damper 16 is interposed between the point a of the air passage 6 and the air outlet 5, and a damper 17 is interposed between the point b of the air passage 3 and the air intake 2. Therefore, when the refrigerator A is operated, the dampers 16 and 17 are closed, and the bypass valve 15 is opened.
Low-temperature air flows directly to the air-to-air heat exchanger 9 bypassing the cooling required room B. In addition, instead of the valve 15 and the dampers 16 and 17 in FIG. 1, a three-way valve is attached to a connection point between the bypass passage 13 and the air passage 6 and the air passage 3, so that air is switched to the bypass passage 13. You can also

In the example shown in FIG. 1, the hot air bypass passage 14 is provided at a point b between the air passage 3 and the air-to-air heat exchanger 9 and between the air-to-air heat exchanger 9 and the expander 10. The hot air bypass passage 14 is provided with a valve 1.
8 are interposed. The bypass valve 18 has a damper structure for opening and closing an air passage, and its opening can be adjusted. The air intake end of the hot air bypass passage 14 is connected to the X in FIG.
In addition to the points, the p point between the air cooler 8 and the air-to-air heat exchanger 9, the q point between the main compressor 7 and the air cooler 8, and the point between the auxiliary cooler 12 and the main compressor 7 R point or auxiliary compressor 1
It may be a point s between 1 and the auxiliary cooler 12. At any point p to s, the compressed air of 0 ° C. or higher flows during the operation of the refrigerator A.

As described above, the apparatus shown in FIG. 1 is provided with the first bypass passage 13 provided with the valve 15 and the hot air bypass passage 14 (second bypass passage) provided with the valve 18. In addition, a drain vent 19 is provided at the lowest position of the air passage from the expander 10 to the air-to-air heat exchanger 9 via the first bypass path 13, and the air exiting the expander 10 needs to be cooled. An ice accumulator 20 is installed in an air passage leading to the chamber B. The ice accumulator 20 has a mesh filter stretched across the air flow path.

Further, there is provided means 21 for discharging the snow-like matter attached to the mesh filter of the ice accumulator 20 to the outside of the ice accumulator 20 as needed. The means 21 for discharging the snow-like material may be mechanical or may be a thermal means for melting the snow-like material to drain. This will be described later.

The operation of the apparatus shown in FIG. 1 will be described below.

If a large amount of general air is present in the cooling required room B at the beginning of the operation, or if outside air or air in the surrounding atmosphere is mixed into the required cooling room B during the operation, the operation of the expander is stopped during the operation of the refrigerator A. Fine ice chips are generated on the exit side, move with the air flow, and accumulate where they are most likely to accumulate. If an ice accumulator 20 having a mesh filter as shown in FIG. 1 is interposed in the air passage on the outlet side of the expander, the ice accumulates preferentially there. Therefore, it is necessary to remove the accumulated snow-like matter. The accumulation of ice fragments generated in the system is often a mixture of suspended particles in the air and ice fragments, and is strictly distinguished from snow and frost, etc., which consist of water. ".

When snow accumulates, the air pressure on the exit side of the expander increases during normal operation. This is detected, and when the detected value exceeds a certain value, the operation for snow removal is started. The main modes of the snow removal operation are ventilation to the first bypass 15 and supply of hot air to the hot air bypass 14. The procedure in the example of FIG. 1 is as follows.

First, the operation of the refrigerator A is stopped, the dampers 16 and 17 are closed, and the valve 15 is opened. Further, the valve 18 of the hot air bypass passage 14 is opened. Thereby, the air pressure in the refrigerator A becomes almost equal to the atmospheric pressure at any position.

As described above, when the pressure in the refrigerator A decreases,
In this state, the refrigerator A is driven. Then, in the example in which the hot air bypass path 14 at the XY point is provided as shown in FIG. 1, the air-to-air heat exchanger 9 → the expander 10 → the bypass path 13 → the air-to-air heat exchanger 9 → the compressor 11 And a second air circuit flowing from the air-to-air heat exchanger 9 → the hot air bypass path 14 → the air-to-air heat exchanger 9 → the compressor 11 is formed. Because the first air circuit initially has a higher resistance than the second air circuit, more air flows through the second air circuit.

If necessary, the flow rate of the cooling water to the auxiliary cooler 12 and the air cooler 8 is reduced or stopped.
When the refrigerator A is driven, the temperature of the circulating air in the system gradually increases, and the temperature of the air exiting from the expander 10 of the first air circuit also becomes 0 ° C. or higher, and further increases. Then, the snow-like material accumulated in the air passage on the low-temperature side begins to melt, the ventilation increases further in accordance with this melting, the air temperature also rises, and eventually the snow-like material completely melts and drains. Becomes During this time, it is possible to control the valve 18 of the hot air bypass passage 14 gradually or to adjust the rotational speed of the compressor so that melting is completed most efficiently and in a short time.

The drain generated in the pipe by the snow removing operation is removed by a drain drain 19 provided at the lowest position of the pipe.
The liquid is naturally collected in the area of, and the collected liquid is discharged out of the system. Also, the drain melted in the ice accumulator 20 is discharged out of the system through a drain provided in the ice accumulator 20. As a result, the snow removal operation is completed. However, if the operation is switched to the normal operation in which the cool air is supplied to the cooling required room B as it is, the cool air is supplied through the heated piping, so that the operation of cooling the heated piping is first performed. Do. This means that the dampers 16 and 17 are closed and the bypass valve 15 is closed.
The operation may be performed with the valve 18 of the hot air bypass passage 14 closed while keeping the valve open. By this pre-cooling operation, the pipeline heated during the snow removing operation is cooled.
17 is opened and the bypass valve 15 is closed to switch to normal operation. Thereby, the supply of warm air to the cooling required room B is prevented, and the cooling required room B is not affected thermally.
It can return to normal operation.

In the drain generated by the snow removing operation, dust and microorganisms in the air which have been present in the snow-like material as nuclei of the snow crystals are also accompanied. Therefore, by performing this snow removal operation, dust and microorganisms existing in the cooling required room B or having entered the required cooling required room B are removed. Purification takes place simultaneously.

In the above-described snow removal operation, the hot air intake end (point X in FIG. 1) of the hot air bypass passage 14 is set to p, q,
The same is true at any point of r and s. In any case, the air at the outlet side of the expander 10 becomes 0 ° C. or higher and continues to rise as the operation proceeds, so that snow melting of the snow-like material is performed. In any case, the air on the outlet side of the expander 10 should be
The temperature can be set to 0 ° C. and, in some cases, 50 ° C.

In order to complete the snow removing operation in a shorter time, an external heat type heater is previously installed at a place where snow-like substances are likely to accumulate, and the snow removing operation and the external heat supply by this heater are combined. Melting of the snow can be further enhanced. A surface-heating type belt heater is conveniently used as a heater mounted inside or outside the pipeline. Ice maker 2
The heat of the externally-heated heater can be transmitted to the mesh filter of No. 0 so that the snow-like material deposited on the mesh filter can be melted by the externally-heated type. As such a filter with a heater, it is convenient to use a net or mesh with a heater, a heater with a fin, or the like.

The apparatus shown in FIG. 1 can be said to be a low-pressure system in which a higher-pressure air at 0 ° C. or higher is introduced into a low-pressure air passage to perform a snow removal operation. Next, FIG. 2 shows an air-refrigerant refrigeration apparatus according to another embodiment (high-pressure system) of the present invention in which high-temperature air is introduced into a high-pressure air path to perform a snow removal operation.

The apparatus shown in FIG.
1 was changed to the position of WZ in FIG.
This shows an apparatus of the present invention having substantially the same equipment configuration as the apparatus described above. Therefore, in FIG. 2, the devices denoted by the same reference numerals as those in FIG. 1 have the same contents as those described in FIG.

In the apparatus shown in FIG. 2, the air passage (Z point) on the inlet side of the expander 10 from the air-to-air heat exchanger 9 to the expander 10, and the air compressor 8 from the main compressor 7 An example is shown in which an air passage (point W) is connected by a hot air bypass passage 22 and a valve 23 is interposed in the hot air bypass passage 22. In this case, when the valve 23 is opened, the air cooler 8 and the air-to-air heat exchanger 9 become air resistance, so that much air flows to the hot air bypass passage 22 side. Therefore, the amount of air cooled by the air cooler 8 and the air-to-air heat exchanger 9 is reduced, and hotter compressed air is sent to the expander 10.

The air intake end to the hot air bypass passage 22 may be located at a position indicated by t, u, or v in FIG. When the connection is made from the point t to the point Z in the drawing, the air-to-air heat exchanger 9 is opened with the valve 23 opened.
When the air that has not passed through the compressor 7, the air cooler 8, and the air-to-air heat exchanger 9 is sent to the expander 10, the air that has not passed through the expander 10 is sent to the expander 10. When connected from point v to point Z, the auxiliary cooler 1
2, the air that has not passed through the compressor 7, the air cooler 8, and the air-to-air heat exchanger 9 is sent to the expander 10. In any case, the hot air bypass passage 22 takes in high-temperature compressed air from the air passage before exiting the compressor and entering the expander before entering the air cooler or air-to-air heat exchanger. Is supplied to the air passage on the inlet side of the compressor, so that when the bypass valve 23 is opened, air at a higher temperature than in the normal operation is sent to the expander 10.

The apparatus using the hot air bypass passage 22 can also perform the snow removing operation by the same operation as described with reference to FIG. That is, the device may be operated with the dampers 16 and 17 closed and the bypass valve 15 and the bypass valve 23 opened. When this operation is started, the air on the outlet side of the expander 10 gradually rises, eventually becomes 0 ° C. or higher, and further rises in temperature. As a result, the snow-like matter in the pipeline melts and is discharged out of the system as a drain as described with reference to FIG.
In order to return to the normal operation after the snow removal operation, as described with reference to the apparatus in FIG. 1, only the valve 23 of the hot air bypass passage 22 is first closed, and the pre-cooling operation of the pipeline is performed.
It is sufficient to open the valves 6 and 17 and close the valve 15 to switch to normal operation.

The apparatus shown in FIG. 2 uses the ice accumulator 20, the snow removing means 21 and the auxiliary heater to perform the snow removing operation more efficiently in the same manner as the apparatus shown in FIG. Can be

As described above, the ice accumulator 20 preferably has a structure in which a mesh filter is arranged so as to cross the air flow path. It can be deposited on a mesh filter. The snow-like object formed on the mesh filter
The drain can be melted by the above-mentioned snow melting operation, but a mechanical scraping means can be further provided.

As an ice accumulator having means for scraping off snow-like objects, a loop-shaped mesh filter is rotatably stretched between rolls in the form of an endless belt, and the mesh belt is installed so as to cross the air passage. In addition, it is preferable that a brush or a blade for scraping off the snow-like material deposited on the mesh belt at the end of the belt is attached. The scraped snow-like material is mechanically discharged to the outside of the system using a screw-type conveyor or a piston system, or a heater is installed inside the snow pit, and the snow-like material in the snow pit is melted by the heater to generate the snow-like material. The drain that has been drained may be discharged outside the vessel.

Further, it is also possible to generate a drain by directly heating the snow-like material attached to the mesh filter with a heater. In this case, the mesh filter itself is formed of a material that generates heat by energizing and heating, and when snow-like material is deposited on the filter, energization is started, and the mesh is collected as a drain and discharged out of the vessel. In addition, a heater member is placed adjacent to or joined separately from the mesh filter or the mesh filter, and similarly, the snow-like material on the mesh filter is melted into drain by electric heating, and the liquid is collected and discharged out of the vessel. You can use what you have. The drainage of the snow-like material by the electric heating can be performed in combination with the snow melting operation of the apparatus of the present invention, or can be performed alone.

The icing device 20 and the snow removing means 2
1 can be provided in the low-temperature air supply side air passage 6 to the cooling required room B, or can be provided in the urethane side air passage 3 from the cooling required room B to the refrigerator A. In the latter case, ice chips and suspended matter generated inside the cooling required room B can be collected before entering the refrigerator A. Alternatively, a plurality of ice accumulators may be arranged in parallel in the air passages 6 and 3 and may be used in a switching manner. Further, a plurality of ice accumulators may be arranged in series to perform collection at a plurality of locations.

[0042]

As described above, according to the present invention,
When the air in the cooling required room is taken in as the refrigerant of the air-cooled refrigerator, and the refrigerant air cooled by the refrigerator is directly blown out to the required cooling room to cool the room, the moisture contained in the air is reduced. When airborne substances accumulate as snow in the pipeline, they can be melted and removed by a simple operation of switching air paths. Therefore, it is possible to prevent a decrease in efficiency or a pause due to a freezing trouble with a simple operation.

In addition, since dust and microorganisms in the air are also taken into the snow-like material generated in the pipeline, clean air is generated in the cooling required room by the generation and removal of the snow-like material. Sent in. For this reason, there is an effect that the air in the cooling required room can be cleaned. The effect of the air purification is particularly useful for forming a cooling room including a freezer, a freezing car, a freezing container, a food display shelf, and the like for storing and transporting food.

[Brief description of the drawings]

FIG. 1 is a diagram showing the equipment arrangement of an embodiment of an air-refrigerant refrigeration apparatus of the present invention.

FIG. 2 is a diagram showing a device arrangement of another embodiment of the air refrigerant refrigeration apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS A Air-refrigerant refrigerator B Cooling required room 7 Main air compressor 8 Air cooler 9 Air-to-air heat exchanger 10 Air expander 11 Auxiliary compressor 12 Auxiliary cooler 13 First bypass path 14 Hot air bypass path 15 Valves of the first bypass path 16, 17 Damper 18 Valve of the hot air bypass path 13 19 Drainage 20 Ice maker 21 Snow removing means 22 Hot air bypass path of another embodiment 23 Valve of the hot air bypass path 22

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Motohisa Uda 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor: Kazuo Furukawa 2-49-1, Numame, Isehara City, Kanagawa Prefecture No. Nihon Honjo Co., Ltd.Isehara Factory

Claims (10)

[Claims] A compressor, an air cooler, an air-to-air heat exchanger, and an expander are arranged in the air path in the order of air flow, and the air in the cooling required room is supplied to the air-to-air heat exchanger. In the air-refrigerant refrigeration apparatus, the air taken out of the expander is blown into the required cooling chamber through the compressor.
A first bypass having valve interposition for returning part or all of the air exiting the expander to the air-to-air heat exchanger, bypassing the cooling chamber, and exiting the compressor to the expander; An air refrigerant having a valve-mounted hot-air bypass path for taking in air of 0 ° C. or more from an air path before entering the air path and supplying the air to an inlet-side air path of an air-to-air heat exchanger. Type refrigeration equipment. 2. A compressor, an air cooler, an air-to-air heat exchanger, and an expander are arranged in the air path in the order of air flow, and the air in the cooling required room is supplied to the air-to-air heat exchanger. In the air-refrigerant refrigeration apparatus, the air taken out of the expander is blown into the required cooling chamber through the compressor.
A first bypass having valve interposition for returning part or all of the air exiting the expander to the air-to-air heat exchanger, bypassing the cooling chamber, and exiting the compressor to the expander; The hot air of the valve interposition for taking hot compressed air from the air passage before entering the air cooler or the air passage before entering the air-to-air heat exchanger and supplying it to the inlet air passage of the expander An air-refrigerant refrigeration system comprising a bypass path. 3. The air intake end to the hot air bypass path may be an air path between a compressor and an air cooler, an air path between an air cooler and an air-to-air heat exchanger, or an air-to-air heat exchanger. The air-refrigerant refrigeration apparatus according to claim 1, wherein the refrigeration apparatus is connected to an air passage between the exchanger and the expander. 4. The air intake end to the hot air bypass path is connected to an air path between the compressor and the air cooler or an air path between the air cooler and the air-to-air heat exchanger. 3. The air-refrigerant refrigeration apparatus according to 2. 5. The air-refrigerant refrigeration system according to claim 1, wherein a drain vent is provided at a lowest position of an air passage from the expander to the air-to-air heat exchanger via the first bypass path. 6. The air-refrigerant refrigeration system according to claim 1, wherein an ice accumulator is installed in an air passage for guiding air that has exited the expander to a cooling required chamber. 7. The air-refrigerant refrigerating apparatus according to claim 6, wherein the ice accumulator is formed by extending a mesh filter so as to cross the air flow path. 8. The air-refrigerant refrigeration system according to claim 6, wherein the ice accumulator captures a mixture of suspended particles and ice pieces in the air. 9. The air-refrigerant refrigeration system according to claim 1, wherein an externally-heated auxiliary heater is attached to an air passage extending from the expander to the air-to-air heat exchanger via the first bypass path. 10. The air-refrigerant refrigeration system according to claim 1, wherein the cooling room is a freezer for storing or transporting food.