JPH01244252A - Refrigerating plant - Google Patents

Abstract

PURPOSE:To prevent the temperature of incoming refrigerant to the compressor for the first closed refrigerant circuit from rising to an abnormal level by connecting an oil cooler for the compressor for the second closed refrigerant circuit by way of a diverting pipe connected to the low pressure side refrigerant pipe which is routed to the suction side of the compressor for the first closed refrigerant circuit. CONSTITUTION:The capacity of an electrical compressor 4 is, for instance, 1.5HP, and the ultimate temperature of respective evaporators 14A, 14B which are being operated becomes about -35 deg.C. At this time, the refrigerant R500 is not totally evaporated in the evaporators 14A, 14B, and so, the refrigerant leaving the accumulator 15 through a low pressure side refrigerant pipe 201 is substantially wet with its temperature at about -25 deg.C. Part of said low temperature gaseous refrigerant enters from the inlet side 202A to a diverting pipe 202, and the remainder returns to the compressor 4 through the suction side pipe 4S. The wet refrigerant entering into the diverting pipe 202 flows into an oil cooler 11 where it exchanges heat with and cool the lubricant in the compressor 10 so as to prevent the seizure of the compressor 10 and the deterioration of the lubricant.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a refrigeration system using a compressor, and particularly to a refrigeration system for obtaining extremely low temperatures using a non-azeotropic mixture of multiple types of refrigerants. .

(b) Prior Art Conventionally, mechanical refrigeration equipment used in freezers used in physical and chemical laboratories and the like to preserve living cells has had a limit of being able to obtain a low temperature of about -80°C.

Although cryopreservation of cells is achieved at such low temperatures, as time passes, the nuclei of ice crystals within the frozen cells recombine and the size of the ice crystals expands, causing cell destruction. . This is called recrystallization of ice, but it is known that this recrystallization of ice does not occur in an environment lower than -130° C., which is the recrystallization point. That is -130℃
Permanent preservation of cells can be achieved at lower ultra-low temperatures.
There have been high expectations for a refrigeration system that can obtain such ultra-low temperatures.

In this type of refrigeration system, especially one using a compressor, the high-temperature gaseous refrigerant discharged from the compressor flows into the condenser and is liquefied by exchanging heat with air or water, and the pressure is adjusted by a pressure reducing device. After that, it flows into an evaporator and is evaporated. At this time, the cooling effect is achieved by absorbing the heat of vaporization from the surroundings, but in a refrigeration system using a single refrigerant, in the case of a normal compressor, -4
The limit is to achieve a minimum temperature of about 0°C.

There is also a so-called dual refrigeration system that uses two independent refrigerant closed circuits, connects them in cascade, and seals a low boiling point refrigerant in the refrigerant closed circuit on the side that achieves the low temperature, thereby achieving a low temperature. However, if a normal compressor is used, the temperature limit is about -80°C.

October 3, 1973 as a solution to these problems.
As in U.S. Pat. No. 3,768,273, a mixed refrigerant of multiple types with different boiling points is used, and the refrigerant with a lower boiling point is successively condensed by evaporating the refrigerant with a higher boiling point in an intermediate heat exchanger. There is also a so-called mixed refrigerant refrigeration system in which the refrigerant with the lowest boiling point is evaporated in the final stage evaporator and a low temperature is obtained using a single compressor.

Further, U.S. Pat. No. 3,733, dated May 22, 1973.
There is also a system, such as No. 845, in which two independent refrigerant closed circuits are connected in cascade, and the refrigerant closed circuit on the low temperature side uses the above-mentioned mixed refrigerant refrigeration system to achieve an extremely low temperature. According to this, it is possible to achieve a low temperature extremely lower than -130°C using a commonly used compressor (for example, about 1.5 HP).

Furthermore, Japanese Patent Application Laid-Open No. 62-73046, which the applicant previously applied for
In this system, the compressor in the closed refrigerant circuit on the low temperature side, which tends to reach high temperatures, is cooled by the low temperature refrigerant sucked into the compressor in the closed refrigerant circuit on the high temperature side, thereby preventing damage to the compressor in the closed refrigerant circuit on the low temperature side due to high temperatures.

(c) Problems to be Solved by the Invention In the above-mentioned Japanese Patent Application Laid-open No. 62-73046, the low pressure side piping of the first refrigerant closed circuit is directly drawn in as an oil cooler of the second refrigerant closed circuit, so the first refrigerant There is a problem in that the temperature of the refrigerant gas sucked into the compressor of the closed circuit becomes too high, and conversely, the compressor of the first refrigerant closed circuit becomes high temperature and is damaged.

The present invention solves these problems and provides a refrigeration system that does not cause failure and can obtain stable cryogenic temperatures.

(D) Means for Solving the Problems The present invention comprises independent first and second refrigerant closed circuits that condense and then evaporate the refrigerant completely discharged from the compressor to exert a cooling effect. The refrigerant closed circuit is filled with multiple types of mixed refrigerants having different boiling points, and the refrigerant pipe is connected between the high-pressure side refrigerant piping from the compressor to the evaporator in the second refrigerant closed circuit and the evaporator in the first refrigerant closed circuit. A heat exchanger is configured in the first refrigerant closed circuit to configure the refrigeration system, and a second
This is an oil cooler for a compressor with a closed refrigerant circuit.

(E) Effect According to the present invention, the low-temperature refrigerant sucked into the compressor of the first closed refrigerant circuit is diverted and a part of it is used for cooling the compressor of the second closed refrigerant circuit. The temperature of the refrigerant sucked into the compressor of the refrigerant closed circuit 1 does not rise abnormally.

(f) Example The invention will now be described in detail with reference to the drawings.

FIG. 1 shows a refrigerant circuit (1) of a refrigeration system (R) of the present invention. The refrigerant circuit (1) is composed of a high temperature side refrigerant circuit (2) as a first refrigerant closed circuit and a low temperature side refrigerant circuit (3) as a second refrigerant closed circuit, which are independent from each other. (4) is an electric compressor that uses a one-phase or three-phase AC power source that constitutes the high temperature side refrigerant circuit (2), and the discharge side piping (4D) of the electric compressor (4) is connected to the auxiliary condenser (5). The auxiliary condenser (5) is further connected to an anti-warning vibrator (6) that heats the opening edge of the freezer storage chamber, which will be detailed later, and then to the oil cooler (7) of the electric compressor (4). After being connected, it is connected to the condenser (8). (9) is a blower for cooling the condenser (8). The high-pressure side refrigerant pipe (200) exiting the condenser 8) passes through the dryer (12) and then passes through the pressure reducer (13) to the first evaporator (14A) as an evaporator part constituting the evaporator. It is connected to the accumulator (15) via the second evaporator (14B), and then to the suction side pipe (of the electric compressor (4) via the low pressure side refrigerant pipe (201)).
4S). The inlet side (202A) and outlet side (202B) of the branch pipe (202) are connected to this low-pressure side refrigerant pipe (201), and the middle part is connected to the low-pressure side refrigerant circuit (3).
) is used as an oil cooler (11) for an electric compressor (10). The first evaporator (14A> and the second evaporator (14B)
) are connected in series, and the high temperature side refrigerant circuit (2) as a whole is connected in series.
evaporator.

The high temperature side refrigerant circuit (2) uses R500, which is an azeotropic mixed refrigerant.
is filled. The high-temperature gaseous refrigerant discharged from the electric compressor 4) is passed through the auxiliary condenser (5) and the nuisance prevention pipe (
6), the oil cooler (7) and the condenser (8) are used to condense and liquefy heat, and then the moisture contained in the dryer (12) is removed, and the pressure is reduced in the pressure reducer (13). 2
The refrigerant R500 flows into the evaporators (14A) and (14B) one after another, evaporates, absorbs the heat of vaporization from the surroundings and cools each evaporator (14A) and (14B>, and the accumulator (14B) as a refrigerant reservoir. 15).

At this time, the capacity of the electric compressor (4) is, for example, 1.5 HP, and the final temperature reached by each evaporator (14A) and (14B> during operation is about -35°C.At this time, the refrigerant R500
is not completely evaporated in each evaporator (14A) and (14B), so the refrigerant that comes out of the accumulator (15) and flows through the low pressure side refrigerant pipe (201) has a high humidity and a temperature of around -25°C. ing. A part of this low-temperature gas refrigerant flows into the branch pipe (202) from the inlet side (202A),
The remaining part is returned to the electric compressor (4) via the suction side pipe (4S) as it is. The highly humid refrigerant that has flowed into the branch pipe (202) reaches the oil cooler (11), where it exchanges heat with the lubricating oil in the electric compressor (10) of the low-temperature side refrigerant circuit (3) and cools it. This prevents seizure of the electric compressor (10) and deterioration of lubricating oil.

The refrigerant coming out of the oil cooler (11) has a temperature of about +20° C. and is sucked into the electric compressor (4) from the outlet side (202B). Therefore, all suction refrigerant is transferred to the oil cooler (
11), the electric compressor (1) of the low temperature side refrigerant circuit <3)
Although the seizure prevention effect of 0) is improved, the temperature of the suction gas refrigerant to the electric compressor (4) in the high temperature side refrigerant circuit (2) becomes too high, causing the electric compressor (4) to seize. This may cause damage. On the other hand, in the present invention, the refrigerant flowing through the low pressure side refrigerant pipe (201) is transferred to the branch pipe (202).
), and for example, 40% is directly transferred to an electric compressor (4
), and 60% of the oil is sucked into the electric compressor (4) via an oil cooler (11).

This prevents seizure of both the electric compressors (4) and (10) and achieves stable operation.

The discharge side pipe (IOD) of the electric compressor (10) constituting the low temperature side refrigerant circuit (3) is connected to an auxiliary condenser (17) and then to an oil separator (18). 18)
From there, it is divided into an oil return pipe (19) that returns to the electric compressor (<10) and a high-pressure side refrigerant pipe (203). High pressure side refrigerant piping (
203), a first condensing pipe (23A) and a second condensing pipe (23B) are connected in series and inserted into the first evaporator (14A) and the second evaporator (14B), respectively. First evaporator (14A) and first condensing vibe (23A)
and second evaporator (14B) and second condensing pipe (23B)
are the cascade capacitor (25A) and (25A) respectively.
B). The second condensing pipe (23B) is connected to the first gas-liquid separator (29) via a dryer (28). The gas phase piping 30) coming out of the gas-liquid separator 29) passes through a first intermediate heat exchanger (32) and is connected to a second gas-liquid separator (33). The liquid phase pipe (34) coming out of the gas-liquid separator (29) is connected between the first intermediate heat exchanger (32) and the second intermediate heat exchanger (42) via a pressure reducer (36). Ru. Liquid phase piping (38) coming out of the gas-liquid separator (33)
) passes through a dryer (39) arranged for heat exchange in the third intermediate heat exchanger (44), and then passes through a pressure reducer (40) to the second intermediate heat exchanger (42) and the third intermediate heat exchanger (44). It is connected between the heat exchangers (44). Gas phase piping coming out of the gas-liquid separator (33)
43) passes through the second intermediate heat exchanger (42),
The dryer (4) passes through the third intermediate heat exchanger (44) and is similarly arranged in the third intermediate heat exchanger (44) for heat exchange.
5) and is connected to a pressure reducer (46). Pressure reducer (46
) is connected to an evaporation pipe (47) as an evaporator, and the evaporation vibe (47) is further connected to a third intermediate heat exchanger (44). The third intermediate heat exchanger (44) is connected to the second (4
2) and the first intermediate heat exchanger (32) one after another, and then connected to the accumulator (49), and the accumulator (49) is further connected to the first suction side heat exchanger (24), Furthermore, it is connected to the suction side piping (105) of the electric compressor (10) via a second suction side heat exchanger (22).

An expansion tank (51) for storing refrigerant when the electric compressor (10) is stopped is connected to the pressure reducer (52) on the suction side pipe (<105).
).

Five types of mixed refrigerants having different boiling points are sealed in the low temperature side refrigerant circuit (3). That is, R22 (chlorodifluoromethane), R12 (dichlorodifluoromethane), R13B
A mixed refrigerant consisting of R1 (promotrifluoromethane), R14 (tetrafluoromethane), and R50 (methane) is sealed in a premixed state. The composition of each refrigerant is, for example, 5.5% by weight of R50, 24.4% by weight of R14,
13B1 is 3967% by weight, R12 is 25.7% by weight,
R22 is 4.7% by weight. R50 is methane, which causes an explosion when combined with oxygen, but the danger of explosion is eliminated by mixing it with each fluorocarbon refrigerant in the above proportions. Therefore, even if a mixed refrigerant leakage accident occurs, an explosion accident will not occur.

In this embodiment, the evaporator of the high-temperature side refrigerant circuit (2) is divided into two evaporator sections, namely, the first evaporator section. Second evaporator (14A).

(14B), and connect the high pressure side piping of the low temperature side refrigerant circuit (3) to the first. Second condensing vibe (23A), (23B)
By dividing it into two cascade capacitors (
25A).

(25B), but it is not limited thereto, and it may be divided into more cascade capacitors without departing from the spirit of the present invention.

Next, to explain the circulation of the refrigerant, the high temperature and high pressure gaseous mixed refrigerant discharged from the electric compressor (10) is transferred to the auxiliary condenser (10).
7), most of the lubricating oil mixed with the refrigerant in the electric compressor (10) is removed from the oil separator (18) through the oil return pipe (19) to the electric compressor (10). The refrigerant itself flows into the first condenser (23A) and the second condenser (23B) one after another, and the refrigerant itself flows into the cascade condenser (25A), respectively.
) and (25B), the first (14A) and second evaporator (
14B) The refrigerant having a high boiling point in the mixed refrigerant can be condensed and liquefied.

The mixed refrigerant that has exited the second condenser (23B) is sent to the dryer (28)
The liquid then flows into the gas-liquid separator (29). At this point, R14 and R50 in the mixed refrigerant have extremely low boiling points, so they have not yet been condensed and are in a gas state, and R22, R12, and R
Since only a part of 13B1 is condensed and liquefied, R14 and R50 are connected to the gas phase pipe (30), R22, R12 and R13
A portion of B1 is separated into liquid phase piping (34). The refrigerant mixture that has flowed into the gas phase pipe (30) is condensed by exchanging heat with the first intermediate heat exchanger (32), and then passes through the gas-liquid separator (33).
). Here, low-temperature refrigerant returning from the evaporator vibrator (47) flows into the first intermediate heat exchanger (32).
Furthermore, after a part of the R13B1 that has flowed into the liquid phase pipe (34) is depressurized by the pressure reducer (36), it is transferred to the first intermediate heat exchanger (3
2) and evaporates there, contributing to cooling, so the temperature of the first intermediate heat exchanger (32) is -60°C.
It's about to happen. Therefore, a portion of the remaining R13B1 and R14 in the mixed refrigerant that has passed through the gas phase pipe (30) is condensed and liquefied, and R50 is still in a gas state because it has a lower boiling point. Therefore, a part of R13B1 and R14 is used as a gas-liquid separator (33
) to the liquid phase pipe (38), R50 and the remaining R14 are separated to the gas phase pipe (43), and part of R13B1 and R14 is depressurized in the pressure reducer (40) via the dryer (39). and a second intermediate heat exchanger (42) and a third intermediate heat exchanger (
44) and evaporates in the second intermediate heat exchanger (42). The return low temperature refrigerant from the evaporator vibrator (47) flows into the second intermediate heat exchanger (42), and the R13B
Since the evaporation of R1 and R14 further contributes to cooling, the temperature of the second intermediate heat exchanger (42) is about -85°C. Furthermore, the third intermediate heat exchanger (44) is equipped with an evaporating vibrator (44).
Because the return low-temperature refrigerant from 7) is flowing in immediately,
Since the temperature is extremely low at about -105°C, the second and third intermediate heat exchangers (42), (
The refrigerant R50 with the lowest boiling point passing through the gas phase pipe (43) that exchanged heat with 44) and the remaining R14 are condensed and liquefied, and after passing through the dryer (45) and reducing the pressure in the pressure reducer (46),
It flows into the evaporation vibe (47) and evaporates there. At this time, the temperature of the evaporating vibrator (47) has reached -140°C. This is the final temperature reached by the refrigeration system (R) of the present invention, and by disposing this evaporating vibrator (47) in a storage compartment of a freezer (to be described later) in a heat exchange manner, the temperature inside the storage compartment is increased to 135°.
It becomes possible to create an ultra-low temperature environment of C. The refrigerant flowing out from the evaporating vibrator (47) is transferred to the third pipe as described above. Second and first intermediate heat exchangers (44), (42), (32
), each refrigerant R14, R13B1 .
While merging with R12 and R22, the accumulator (49
) After separating the unevaporated refrigerant, the electric compressor (10)
is inhaled.

Here, the liquid phase piping (34) is connected to the first gas-liquid separator (29).
R12 and R22 flowing into the first intermediate heat exchanger (32
), but since the temperature is already extremely low, it does not evaporate and remains in a liquid state, so it does not contribute equally to cooling, but residual lubricating oil and various other oils that could not be separated by the oil separator (18) do not evaporate and remain in a liquid state. It functions to return the mixed moisture that has not been completely absorbed by the dryer to the electric compressor (10) in a dissolved state. When the lubricating oil and water of the electric compressor (10) circulate in the low-temperature side refrigerant circuit (13), the extremely low temperature causes them to remain in various parts, causing clogging. Therefore, R12 and R22 achieve almost complete return of lubricating oil and moisture.

By repeating the above, the refrigerant circuit (1) operates to generate an extremely low temperature of -140"C in the evaporator vibrator (47) in a steady state, but the electric compressors (4) and (10)
．． It only requires an ability of about 5 HP, and does not require any particularly great ability. This is a cascade capacitor (25A), (
25B) The fact that heat exchange is well performed and the selection of the mixed refrigerant greatly contribute to this. This achieves noise reduction and power consumption by the electric compressor. or,
By achieving -140''C, it becomes possible to cool biological materials in the freezer to a temperature lower than the recrystallization point of ice, which will be described later, and permanent preservation will be achieved.

Next, FIG. 2 shows a front perspective view of a freezer (75) to which the present invention is applied, and FIG. 3 shows a sectional view of a main part thereof. Furthermore, the fourth
The figure is a diagram illustrating a specific configuration of a refrigerant circuit (1) of a refrigeration system (R). The freezer (75) is installed in physical and chemical laboratories, etc., and (74) is the storage room (74) with an upward opening.
6) is formed inside, and its upper opening is closed so as to be openable and closable by a heat insulating door (77) rotatably supported at the rear side. On the side of the main body (74) are a temperature regulator (61) and an electric compressor (4).

A machine room (78) is formed to house (10), etc., and in front of it there is a self-recording temperature recorder (79) that senses the temperature in the storage room (76) and records its time course on recording paper.
) and a well-known alarm device (80) that issues an alarm in case of abnormally high temperature in the storage room (76), and a knob (81) for changing the settings of the temperature controller 61 is provided. Further, (82) is a ventilation slit.

Figure 3 shows a side sectional view of the main body (74> section.
83) is an outer box made of steel plate with an upward opening, (84> is an inner box made of aluminum with an upward opening, and the inner box (84) is assembled into the outer box (83), and the inner box (83), ( 84)
In between are separate box-shaped external insulation materials with upward openings (
A double heat insulating layer consisting of a box (85) and an inner heat insulating material (86) is formed, and the opening edges of both boxes (83) and (84) are connected by a breaker (87). An evaporation vibrator (47) is disposed on the outer surface of the inner box (84) in a thermally conductive manner, and an inner heat insulating material (
86), and an anti-frost vibrator (6) is thermally conductively disposed on the inner surface of the opening edge of the outer box (76).

The inner heat insulating material (86) is placed inside the outer heat insulating material (85) and is completely separated, so the evaporating vibrator (47)
Even if the inner insulation material (86) contracts due to the cooling effect of be. An opening (88) is formed on the back surface of the outer box (83),
In addition, the external insulation material (85) also has a corresponding notch (89).
is formed, and an opening (88) is formed in the notch (89).
Cascade capacitors (25A), (25B), etc. molded with a heat insulating material (90) as described later are housed and covered with a cover plate (91). (92
) is a styrofoam inner lid, (93> is an insulated door (77)
) A gasket on the inner circumferential surface, (94) are transporting casters.

Next, FIG. 4 shows a specific configuration of the refrigerant circuit (1) of the refrigeration system (R), in which the same reference numerals as in FIG. 1 are the same. The auxiliary condenser (17) of the low temperature side refrigerant circuit (3) is connected to the high temperature side refrigerant circuit (2) in contrast to the air suction type blower (9).
) is placed on the windward side of the condenser (8) so that it is cooled at the same time. First and second evaporators (14A),
(14B) has the shape of a hollow tank, into which first and second condensing vibes (23A) and (23B), which are spirally wound, are respectively inserted from above. (96) is each intermediate heat exchanger (32), (4
2), (44), etc., and is molded with a heat insulating material (97) to form a box-like intermediate heat exchanger section. The evaporation vibrator (47) is fixed in advance to the outer surface of the inner box (84) in a meandering manner using aluminum tape or an adhesive, but in order to minimize the temperature distribution inside the storage chamber (76). The order in which the refrigerant flows is
It is arranged so as to go around the upper part of the inner box (84), go around the lower part, and finally go around the bottom side.

(G) Effects of the Invention Since the present invention has the above configuration, a heat exchanger is configured between the evaporator of the first refrigerant closed circuit and the high pressure side piping of the second refrigerant closed circuit, and the second When the refrigerant closed circuit is filled with a mixture of multiple types of refrigerants with different boiling points, the second refrigerant closed circuit is connected to the first refrigerant closed circuit by a branch pipe connected to the low pressure side pipe leading to the suction side of the compressor. Since the oil cooler for the compressor is configured, a part of the low-temperature refrigerant flowing through the low-pressure side piping of the first refrigerant closed circuit and returning is sucked into the compressor as it is.
After cooling the compressor of the second refrigerant closed circuit, a part of the refrigerant is sucked into the compressor of the first refrigerant closed circuit. It is possible to prevent seizure of the compressor of the second refrigerant closed circuit, achieve stable cooling operation, and stably obtain an extremely low freezing temperature using a normal compressor.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram of the refrigeration device, FIG. 2 is a perspective view of the freezer, FIG. 3 is a side sectional view of the freezer body, and FIG. 4 is a diagram showing a specific configuration of the refrigerant circuit of the refrigeration device. (2)...High temperature side refrigerant circuit, (3)...Low temperature side refrigerant circuit, (4), (10)...Electric compressor,
(11)...Oil cooler, (201)...Low pressure side refrigerant piping, (202>...Branch piping.

Claims (1)

[Claims] 1. It consists of independent first and second refrigerant closed circuits that each condense and evaporate the refrigerant discharged from the compressor to exert a cooling effect, and the second refrigerant closed circuit has multiple refrigerant circuits with different boiling points. configuring a heat exchanger between the high pressure side refrigerant piping from the compressor to the evaporator of the second refrigerant closed circuit and the evaporator of the first refrigerant closed circuit; A refrigeration system characterized in that an oil cooler for a compressor in the second refrigerant closed circuit is configured by a branch pipe connected to a low-pressure side refrigerant pipe leading to a suction side of the compressor in the first refrigerant closed circuit.