JPH0697123B2 - Refrigeration equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refrigerating apparatus using a compressor, and more particularly to a refrigerating apparatus for obtaining a cryogenic temperature by using a plurality of non-azeotropic mixed refrigerants. .

(B) Conventional technology Conventional mechanical refrigeration equipment used in freezers used for storage of living cells in physics and chemistry laboratories, etc. had a limit of obtaining a low temperature of about -80 ° C. Although cryopreservation of cells is achieved by such low temperature, over time, ice crystal nuclei in frozen cells are recombined with each other to enlarge the size of ice crystals and cause cell destruction phenomenon. . This is called ice recrystallization, but it is known that this ice recrystallization does not occur in an environment lower than the recrystallization point of −130 ° C. That is, permanent storage of cells can be achieved under ultra-low temperature lower than -130 ° C, and a refrigerating apparatus for obtaining such ultra-low temperature has been expected.

Here, in this type of refrigerating apparatus, especially in the case of using a compressor, the high temperature gaseous refrigerant discharged from the compressor is made to flow into a condenser and is liquefied by exchanging heat with air or water, and the pressure is adjusted by a decompressor. After that, it is allowed to evaporate by flowing into an evaporator. At this time, the cooling action 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, the
The maximum limit is to reach the lowest temperature of about ℃.

There is also a so-called dual refrigeration system in which two independent closed refrigerant circuits are used, both are connected in cascade, and a low-boiling-point refrigerant is sealed in the closed refrigerant circuit on the side that achieves a low temperature to achieve a low temperature. However, in the case of using a normal compressor, the limit is about -80 ° C.

As a solution to these problems, as shown in US Pat. No. 3,768,273 dated October 3, 1973, a mixed refrigerant having a plurality of different boiling points is used, and a lower boiling point is obtained by evaporating the higher boiling point refrigerant in the intermediate heat exchanger. There is also a so-called mixed refrigerant refrigeration system in which the refrigerant having the lowest boiling point is evaporated in the final stage evaporator by condensing the refrigerant having the boiling point one after another, and a low temperature is obtained by a single compressor.

Furthermore, as in US Pat. No. 3,733,845 dated May 22, 1973, two independent closed refrigerant circuits are cascade-connected, and the closed refrigerant circuit on the low temperature side has the aforementioned mixed refrigerant refrigeration system to achieve an extremely low temperature. . According to this, it is possible to achieve an extremely low temperature lower than -130 ° C by a commonly used compressor (for example, about 1.5 HP).

(C) Problems to be solved by the invention In the case of using such a mixed refrigerant refrigeration type refrigerant closed circuit, since the final reached temperature is an extremely low temperature of −130 ° C. or less as described above, Since the refrigerant easily evaporates and vaporizes in the decompressor at the final stage due to the invasion of heat, a sufficient amount of liquid refrigerant cannot be supplied to the evaporator, resulting in insufficient cooling.

In order to prevent such a situation, the vicinity of the evaporator of the cooling device is particularly severely insulated, but there is a limit to that as well, and such lack of cooling also occurs due to the imbalance of the amount of refrigerant to be charged. To do.

That is, if the amount of refrigerant to be filled is too large, the refrigerant will not evaporate completely in the evaporator and will return to the final stage intermediate heat exchanger as a liquid, and this intermediate heat exchanger will be at the same temperature as the evaporator. Will be cooled down. In such a situation, the refrigerant passing therethrough and exchanging heat is supercooled, and the heat entering from the outside causes the refrigerant to start to evaporate in the decompressor at the final stage. As a result, the circulation of the refrigerant in the decompressor is obstructed, the refrigerant is not supplied to the evaporator, and insufficient cooling occurs.

On the contrary, even if the amount of the refrigerant to be charged is too small, sufficient evaporation of the refrigerant cannot be performed in the evaporator, so that insufficient cooling still occurs.

The present invention has been made to solve such problems.

(D) Means for Solving Problems The configuration of the present invention will be described along with examples. The low temperature side refrigerant circuit (3) includes an electric compressor (10), a cascade condenser (25A) (25B), an evaporation pipe (47), first, second and third intermediate heat exchangers (32) (42) ( 44).
Each intermediate heat exchanger is connected in series so that the return refrigerant from the evaporation pipe (47) flows in the order of (44), (42) and (32).
The refrigerant circuit (3) mixes and encloses a plurality of kinds of refrigerants having different boiling points (that is, different evaporation temperatures), and cascade condensers (25A) (25B) and intermediate heat exchangers (32) (42) (44).
Refrigerant with a high boiling point condensed in multiple decompressors (36) (40)
After decompressing at (46), they are successively introduced into the intermediate heat exchangers (32) (42) to condense uncondensed refrigerant, and the R50 refrigerant with the lowest boiling point is passed through the decompressor (46) at the final stage. It is made to flow through the evaporation pipe (47) and evaporated to obtain an extremely low temperature of -150 ° C. At this time, the temperature of the refrigerant flowing into the pressure reducer (46), that is, the temperature of the inlet portion (P ₁ ) of the pressure reducer (46) and the temperature of the refrigerant after leaving the pressure reducer (46), that is, the inlet portion of the evaporation pipe (47) ( the difference between the temperature of the P ₂₎ is greater than 10 ° C., and under reduced pressure differences 100 ° C. in a temperature (-150 ° C.) of the cascade condenser (25A) (the evaporation pipe temperature 25B) (-50 ℃) (47 ) Bowl (36) (40) (46)
The refrigerant is sealed so that the value becomes smaller than 33 ° C divided by the number of.

(E) Action When the temperatures at points (P ₁ ) and (P ₂ ) are close to each other, it means that there is too much refrigerant and the amount of liquid refrigerant is flowing into the third intermediate heat exchanger (44). Also, when the temperature difference is large, the amount of refrigerant filled is too large to evaporate only near the inlet of the evaporation pipe (47), so an appropriate amount can be filled by setting it between 10 ° C and 33 ° C. As a result, pulsation of the temperature of the evaporation pipe (47) and insufficient cooling can be prevented, stable cooling performance can be exhibited, and the refrigeration system (R) can be provided with high reliability and life.

(F) Example Next, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a refrigerant circuit (1) of the 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 of each other.
(4) is an electric compressor using a one-phase or three-phase AC power source that constitutes the high temperature side refrigerant circuit (2), and the discharge side pipe (4D) of the electric compressor (4) is connected to the auxiliary condenser (5). The auxiliary condenser (5) is connected to a dew-prevention pipe (6) for heating the storage chamber opening edge of the freezer, which will be described in detail later.
Next, it is connected to the oil cooler (7) of the electric compressor (4) and then to the condenser (8). (9) is a blower for cooling the condenser (8). The refrigerant pipe exiting the condenser (8) passes through the dryer (12), and then the first evaporator (14A) as an evaporator portion constituting the evaporator via the pressure reducer (13).
After being connected to the accumulator (15) via the second evaporator (14B) and the second evaporator (14B), the electric compressor (4) is passed through the oil cooler (11) of the electric compressor (10) forming the low temperature side refrigerant circuit (3). Is connected to the suction side pipe (4S). The first evaporator (14A) and the second evaporator (14B) are connected in series, and constitute the evaporator of the high temperature side refrigerant circuit (2) as a whole.

Refrigerants R502 and R12 having different boiling points are provided in the high temperature side refrigerant circuit (2).
(Dichlorodifluoromethane), and the composition thereof is, for example, 88.0% by weight of R502 and 12.0% by weight of R12. After the high temperature gaseous refrigerant discharged from the electric compressor (4) is condensed in the auxiliary condenser (5), the dew prevention pipe (6), the oil cooler (7) and the condenser (8) to be radiated as heat radiation. ,
Water contained in the dryer (12) is removed, and the decompressor (13)
The refrigerant R502 is decompressed by the first and second evaporators (14A) and (14B) one after another to evaporate the refrigerant R502, absorb the heat of vaporization from the surroundings, and cool each evaporator (14A) (14B). , And returns to the electric compressor (4) from the accumulator (15) as a refrigerant liquid reservoir via the oil cooler (11) of the electric compressor (10) of the low temperature side refrigerant circuit (3).

At this time, the capacity of the electric compressor (4) is, for example, 1.5 HP, and the final reached temperature of each evaporator (14A) (14B) in operation becomes -50 ° C. Under such a low temperature, R12 in the refrigerant does not evaporate in the evaporators (14A) and (14B) and remains in a liquid state, so that it hardly contributes to cooling, but it does not contribute to the cooling, but the lubricating oil and the drying of the electric compressor (4). It has the function of returning the mixed water, which has not been completely absorbed by the container (12), to the electric compressor (4) in a state of being dissolved therein. That is, the R12 refrigerant is the accumulator (1
5) For oil return that is usually formed at the lower end of the pipe (inserted from above into the accumulator (15) and bent at the lower end so that the open end faces above the refrigerant liquid level) It comes out of the accumulator (15) through the hole and flows into the oil cooler (11) of the low temperature side refrigerant circuit (3) in a liquid state containing the above-mentioned lubricating oil and the like. R12 evaporates due to the high temperature of the electric compressor (10), which prevents seizure of the electric compressor (10) and deterioration of the lubricating oil. That is, the refrigerant R12 has a function of returning the lubricating oil in the high temperature side refrigerant circuit (2) to the electric compressor (4) and a low temperature side refrigerant circuit (3).
It has the function of cooling the electric compressor (10).

The discharge side pipe (10D) of the electric compressor (10) forming the low temperature side refrigerant circuit (3) is connected to the auxiliary oil separator (18) connected to the auxiliary condenser (17). The oil separator (18) is divided into an oil return pipe (19) returning to the electric compressor (10) and a pipe connected to the dryer (20), and the dryer (20) is a branch three-way pipe (21). Connected. One of the pipes extending from the three-way pipe (21) is the second suction side heat exchanger (22) of the low temperature side refrigerant circuit (3).
After the surroundings are wound by heat exchange, they are connected to a first condensing pipe (23A) as a high-pressure side pipe inserted in the first evaporator (14A). Similarly, the other pipe extending from the three-way pipe (21) is wound around the first suction side heat exchanger (24) of the low temperature side refrigerant circuit (3) in a heat exchange manner and then the second evaporator (14B). It is connected to the second condensing pipe (23B) as a high-pressure side pipe inserted inside. First evaporator (14A) and first condensing pipe (23A)
Also, the second evaporator (14B) and the second condensing pipe (23B) constitute cascade condensers (25A) and (25B), respectively. The first and second condensing pipes (23A) and (23B) are connected by the collecting three-way pipe (27) and then connected to the first gas-liquid separator (29) via the dryer (28). Gas-liquid separator (29)
The gas-phase pipe (30) exiting from the inside passes through the inside of the first intermediate heat exchanger (32) and is connected to the second gas-liquid separator (33). The liquid phase pipe (34) coming out of the gas-liquid separator (29) goes through the dryer (35) and then the pressure reducer (36), and then the first intermediate heat exchanger (32) and the second intermediate heat exchanger. Connected between (42). The liquid-phase pipe (38) coming out of the gas-liquid separator (33) goes through a dryer (39) arranged in heat exchange with a third intermediate heat exchanger (44) and then through an evaporator (40). It is connected between the second intermediate heat exchanger (42) and the third intermediate heat exchanger (44). The gas-phase pipe (43) exiting from the gas-liquid separator (33) passes through the second intermediate heat exchanger (42) and then through the third intermediate heat exchanger (44), and similarly. The third intermediate heat exchanger (44) is connected to the pressure reducer (46) via the dryer (45) arranged in a heat exchange manner. The decompressor (46) is connected to an evaporation pipe (47) as an evaporator,
Further, the evaporation pipe (47) is connected to the third intermediate heat exchanger (44). The third intermediate heat exchanger (44) is connected to the second (42) and the first intermediate heat exchanger (32) one after another, and then to the accumulator (49), and the accumulator (49) is further Connected to the suction side heat exchanger (24)
Is connected to the suction side pipe (10S) of the electric compressor (10) via the suction side heat exchanger (22). An expansion tank (51) that stores a refrigerant when the electric compressor (10) is stopped is further connected to the suction side pipe (10S) via a pressure reducer (52).

The low temperature side refrigerant circuit (3) is filled with four kinds of mixed refrigerants having different boiling points. That is, a mixed refrigerant composed of R12 (dichlorodifluoromethane), R13B1 (bromotrifluoromethane), R14 (tetrafluoromethane) and R50 (methane) is sealed in a premixed state. The composition of each refrigerant is, for example, R50 4.0% by weight, R14 22.0% by weight, R13B1 39.0% by weight.
% By weight, R12 is 35.0% by weight. R50 is methane, which causes an explosion when combined with oxygen, but the danger of explosion disappears when mixed with each CFC refrigerant in the above proportion. Therefore, even if the mixed refrigerant leaks, no explosion will occur.

Here, in the embodiment, the evaporator of the high temperature side refrigerant circuit (2) is divided into two evaporator parts, that is, the first and second evaporators (14A) (14B), and the high pressure side piping of the low temperature side refrigerant circuit (3) is connected. Although the two cascade condensers (25A) and (25B) are configured by dividing the first and second condensing pipes (23A) and (23B), the present invention is not limited to this, and a larger number of cascade condensers can be used without departing from the spirit of the present invention. There is no problem even if it is divided into capacitors.

Next, the circulation of the refrigerant will be described. The high temperature and high pressure gaseous mixed refrigerant discharged from the electric compressor (10) is an auxiliary condenser (17).
After being pre-cooled by the oil separator (18), most of the lubricating oil of the electric compressor (10) mixed with the refrigerant in the oil separator (18) is returned to the oil return pipe (1
At 9), return it to the electric compressor (10) and remove the refrigerant itself from the dryer (2
After going through 0), it is divided into two by a three-way tube (21). Three-way tube (2
The refrigerant bisected in 1) is separately precooled in the suction side heat exchanger (22) or (24), and then is first cooled in the cascade condenser (25A) or (25B).
After being cooled by (14A) or the second evaporator (14B) to condense and liquefy a part of the high-boiling-point refrigerant in the mixed refrigerant, it joins in the three-way pipe (27). At this time, the mixed refrigerant is divided into two and cooled in the cascade condenser (25A) or (25B) separately in a small amount,
Sufficient heat exchange takes place and the condensation effect is achieved well.

The mixed refrigerant discharged from the three-way pipe (27) flows into the gas-liquid separator (29) via the dryer (28). At this point R1 in the mixed refrigerant
4 and R50 are not condensed yet in a gas state because they have extremely low boiling points, and only R12 and R13B1 are condensed and liquefied, so R14 and R50 are in the gas phase pipe (30), and R12 and R13B1 are liquid. It is separated into phase piping (34). The refrigerant mixture flowing into the gas phase pipe (30) exchanges heat with the first intermediate heat exchanger (32) to be condensed, and then reaches the gas-liquid separator (33). Here, the low-temperature refrigerant returned from the evaporation pipe (47) flows into the first intermediate heat exchanger (32), and further flows into the liquid phase pipe (34) R1.
After 3B1 is decompressed by the decompressor (36) after passing through the dryer (35), it flows into the first intermediate heat exchanger (32) and evaporates there, thereby contributing to cooling. The temperature of the exchanger (32) is about -80 ° C. Therefore, most of 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 its boiling point is lower.
Therefore, R14 is separated from the gas-liquid separator (33) to the liquid-phase pipe (38) and R50 is separated to the gas-phase pipe (43), and R14 is decompressed by the decompressor (40) via the dryer (39). Then, it flows between the second intermediate heat exchanger (42) and the third intermediate heat exchanger (44) and evaporates in the second intermediate heat exchanger (42). Since the return low temperature refrigerant from the evaporation pipe (47) flows into the second intermediate heat exchanger (42) and the evaporation of R14 further contributes to cooling, the temperature of the second intermediate heat exchanger (42) is It is about -100 ℃. Furthermore, since the return low-temperature refrigerant from the evaporation pipe (47) immediately flows into the third intermediate heat exchanger (44), the temperature is extremely low, about -120 ° C. Refrigerant with the lowest boiling point that passes through the gas-phase pipe (43) that has exchanged heat with the second and third intermediate heat exchangers (42) (44)
R50 is condensed and liquefied, and goes through a dryer (45) and then a pressure reducer (46).
After being decompressed at, it flows into the evaporation pipe (47) and evaporates there. At this time, the temperature of the evaporation pipe (47) is -150 ° C.
Has reached. This is the final reached temperature of the refrigerating apparatus (R) of the present invention, and by disposing this evaporation pipe (47) in the storage chamber of the freezer described later in a heat exchange manner, the inside of the storage chamber becomes an environment of ultra-low temperature of -140 ° C. It becomes possible to do. The refrigerant (mostly R50) flowing out from the evaporation pipe (47) is the third, second and first intermediate heat exchangers (44) (42) as described above.
Refrigerants R14, R13B1, R12 flow into and out of (32) one after another.
While merging with the above, the non-evaporated refrigerant is separated by the accumulator (49) and then flows into the suction side heat exchangers (24) (22) one after another for cooling and then sucked into the electric compressor (10).

Here, R12 that has flowed into the liquid-phase pipe (34) in the first gas-liquid separator (29) flows into the first intermediate heat exchanger (32), but since it has already reached an extremely low temperature, it evaporates. It remains liquid and does not contribute to cooling, but the residual lubricating oil that could not be completely separated by the oil separator (18) and the mixed water that could not be completely absorbed by each dryer are dissolved in it. It has the function of returning to the electric compressor (10) in the closed state. The lubricating oil of the electric compressor (10) is the low temperature side refrigerant circuit (13).
When it circulates in the inside, the phenomenon that it remains in each part occurs due to the extremely low temperature, which causes clogging. Therefore, R12 has achieved almost complete return of lubricating oil.

By repeating the above, the refrigerant circuit (1) operates to generate an ultra-low temperature of -150 ° C in the evaporation pipe (47) in a steady state, but the electric compressor (4) (10) has a capacity of about 1.5 HP. It doesn't require any special ability. This is due to good heat exchange between the cascade condensers (25A) and (25B) and the selection of the mixed refrigerant. As a result, noise reduction and low power consumption by the electric compressor are achieved. Further, by achieving -150 ° C, it becomes possible to cool the biological material in the freezer described below to a temperature lower than the recrystallization point of ice, and permanent storage is achieved. Furthermore, since the refrigerant in the high temperature side refrigerant circuit (2) flows from the first evaporator (14A) to the second evaporator (14B) and does not split, the temperature balance between both evaporators (14A) (14B) is not whatsoever. Even if it collapses due to such a cause, the deviation of the refrigerant flow rate cannot occur, and therefore, the first condensing pipe (23) of the low temperature side refrigerant circuit (3)
Stable cooling between A) and the second condensing pipe (23B) is achieved, and good condensing action is achieved.

Next, FIG. 2 shows an outline of an electric circuit for controlling the refrigerating apparatus (R) of the present invention. (4M) is a motor for driving the electric compressor (4) of the high temperature side refrigerant circuit (2), which is connected between one-phase or three-phase AC power supplies (AC) (AC). That is, the motor (4M) is continuously operated while the power (AC) (AC) is turned on. (10M) is a motor for driving the electric compressor (10) of the low temperature side refrigerant circuit (3), and an electromagnetic relay (60)
Is connected to the power supply (AC) (AC) in series with the contact (60A). The contact (60A) is energized and closed by the coil (60C) of the electromagnetic relay (60) to operate the motor (10M). (6
1) is a freezer storage room temperature controller described later, which is connected between the power supply (AC) (AC), detects the temperature inside the storage room substantially, and sets an appropriate differential above and below the set temperature, A voltage is generated between the output terminals (61A) and (61B) at the upper limit temperature and stopped at the lower limit temperature. This set temperature is −
145 ° C to -150 ° C. Between the output terminals (61A) and (61B), the coil (62C) of the temperature control relay (62) and the timer (63)
Contacts (63A) are connected in series. The temperature control relay (62) energizes the coil (62C) to close the contact (62A). (6
5) is the electric compressor (1) of the low temperature side refrigerant circuit (3) in FIG.
0) A high-pressure switch provided in the discharge side pipe (10D) in the front side of the auxiliary condenser (17). The high pressure switch (65) is connected to the power supply (AC) (AC) in series with the timer (63), and the pressure on the discharge side of the electric compressor (10) rises and the compressor (10) is overloaded. When the pressure becomes high, for example, 26 kg / cm ² , the contact is opened, and when the pressure is sufficiently safe, for example, 8 kg / cm ² , the contact is closed. After the contact of the high-voltage switch (63) is closed, the timer (63) is set to 3
After 5 minutes, the contact (63A) is closed and the high voltage switch (6
5) opens and the contact (63A) opens. (66) is a cold start thermostat, and is attached so as to detect the temperature of the accumulator (15) of the high temperature refrigerant circuit (2). Since the refrigerant evaporated in each evaporator (14A) (14B) and the refrigerant not yet evaporated flow into the accumulator (15), the evaporator (14
A) (14B) has almost the same low temperature, but the low temperature starting thermostat (66) closes the contacts when the temperature of the accumulator (15) drops to, for example, -35 ° C and rises to -10 ° C. Open the contact. Cold start thermostat (6
6) forms a series circuit with the contacts (62A) of the temperature control relay (62) and the timer (68) on both sides and is connected to the power supply (AC) (AC). The common terminal of the changeover switch (69) of the timer (68) is connected between the timer (68) and the cold start thermostat (66), and the electromagnetic switch is connected between the terminal (69A) of the changeover switch (69) and the power supply (AC). The coil (60C) of the relay (60) is connected, and the heaters (70) (71) exchangeably provided before and after the pressure reducer (46) of FIG. 1 are connected between the terminal (69B) and the power supply (AC). Connected in parallel. The timer (68) always closes the changeover switch (69) to the terminal (69A), energizes and integrates, and when this integration reaches 12 hours, closes the switch (69) to the terminal (69B) for 15 minutes, for example. To close the terminal (69A) again.

Next, the operation will be described with reference to the timing chart of FIG. When the refrigeration system (R) is installed and the power (AC) (AC) is turned on at time (t ₀ ), the motor (4M) starts up,
The electric compressor (4) operates and the refrigerant starts to circulate in the high temperature side refrigerant circuit (2). At this time, the accumulator (15) is in a state close to room temperature, so the cold start thermostat (66)
Is in the open state, so the coil (60C) of the electromagnetic relay (60) is not energized regardless of the temperature controller (61), and therefore the contact (60A) is open, so the motor (10M) Does not start, and the electric compressor (10) of the low temperature side refrigerant circuit (3) does not operate. Such high temperature side refrigerant circuit (2)
Only the cooling operation is continued and the first and second evaporators (14
When the liquid refrigerant accumulates in A) (14B), the temperature decreases, and the temperature of the accumulator (15) decreases accordingly, and when it reaches −35 ° C at time (t ₁ ), the low temperature starting thermostat (66) turns on. Close the contact. Immediately before this closing operation, the electric compressor (10) is stopped, so the high pressure switch (65) is naturally closed, and since 3 to 5 minutes have naturally passed since the power was turned on, the timer (63 ) Also contacts (63A)
Is closed. Further, since the temperature in the storage chamber is naturally higher than the set temperature, the temperature controller (61) also produces an output, so that the contact (62A) of the temperature control relay (62) is closed. Therefore, when the cold start thermostat (66) is closed, the coil (60C) of the electromagnetic relay (60) is energized, the contact (60A) is closed, the motor (10M) is activated, and the mixed refrigerant is fed from the electric compressor (10). Is discharged and begins to circulate in the circuit (3). At this time, the temperature of each part of the low temperature side refrigerant circuit (3) is still high, and therefore the internal refrigerant is mostly in a gaseous state, so that the pressure in the circuit is high. Moreover, since the refrigerant is pushed out from the electric compressor (10), the pressure in the discharge side pipe (10D) rapidly rises. If this is left unattended, the high pressure causes the electric compressor (1
0) The component is damaged, but when the peak value of this pressure rise reaches the allowable limit of 26 kg / cm ² at time (t ₂ ), the high pressure switch (65) senses it and opens the contact. (63A) opens, which forcibly opens the contact (62A) of the temperature control relay (62), de-energizes the coil (60C), opens the contact (60A), and stops the motor (10M). . This prevents pressure rise on the discharge side of the electric compressor (10) and prevents damage.

When the electric compressor (10) is stopped, the pressure in the discharge side pipe (10D) drops to 8 kg / cm ² , but due to the presence of the chattering prevention timer (63), the high pressure switch (65)
The contact does not close for 3 to 5 minutes after the closing operation of the motor, so the motor (10M) does not start. During this time, the pressure in the low temperature side refrigerant circuit (3) is set to the first or second evaporator (14A) (14A).
Since the refrigerant cooled from B) from the first or second condenser (23A) (23B) is circulated and evaporated to some extent, the temperature is lowered and the pressure is also reduced from the previous start. There is. When the delay time by the timer (63) has passed the time (t ₃ ), the contact (63A) is closed again and the motor (10M) is started as described above, but the pressure in the discharge side pipe (10D) is
When the pressure reaches 26 kg / cm ² , the high pressure switch (65) opens again and the motor (10) stops. Such a motor (10
M) is repeatedly started and stopped, the refrigerant with a high boiling point evaporates, and the cooling action is gradually exerted, whereby the temperature gradually decreases from the first intermediate heat exchanger (32). , When the peak value of the pressure rise in the discharge side pipe (10D) at the time of starting the motor (10M) does not reach 26 kg / cm ² , the motor (10M)
Enters continuous operation.

When the electric compressor (10) is continuously operated, the refrigerant having a low boiling point is also condensed and gradually begins to exert a cooling action, and each intermediate heat exchanger (32) (42) (44) and the evaporation pipe (47). The temperature is gradually decreased to obtain the final reached temperature. After that, when the temperature of the storage chamber reaches the lower limit temperature set by the temperature controller (61), the output between the output terminals (61A) and (61B) is stopped, so the contact (62A) opens and the contact (60A) opens.
Since A) also opens, the motor (10M) stops and the cooling operation stops. After that, when the temperature in the storage chamber gradually rises and reaches the upper limit temperature set by the temperature controller (61), the contact (62A) is closed again, and the contact (60A) is closed, and the motor (10A) is closed.
M) is started and the cooling operation is started again. By repeating the above, the storage chamber is maintained at the set temperature, for example, −140 ° C. on average.

Here, the timer (68) keeps the contact (62A) and the cold start thermostat (66) closed, that is, the motor (10).
M) is operating, and the total is 1
When it reaches 2 hours, the changeover switch (69) is closed to the terminal (69B), so the operation of the motor (10M) is prohibited, and the heaters (70) (71) are energized to generate heat. Here, R50 flowing out of the third intermediate heat exchanger (44) and flowing into the pressure reducer (46) has reached an extremely low temperature of −120 ° C. or lower. Therefore, if a very small amount of water (which enters during the replenishment work of the refrigerant, etc.) is mixed in this refrigerant, icing will occur in the pipe. By the way, since the decompressor is usually constituted by a pipe having a small diameter, if ice builds up in this decompressor (46), clogging occurs and the refrigerant stops flowing, but in the present invention, the heater (70) ( Because the pressure reducer (46) is heated regularly by 71), this ice crystal does not melt and grow, thus preventing such an accident. The heat generation of this heater (70) (71) ends in 15 minutes, and again the terminal (69A)
Then, the switch (69) is closed, the motor (10M) is started, and the cooling operation of the low temperature side refrigerant circuit (3) is started as described above.

Next, FIG. 4 shows a front perspective view of a freezer (75) to which the present invention can be applied, and FIG. 5 shows a cross-sectional view of an essential part thereof. Further, FIG. 6 is a diagram illustrating a specific configuration of the refrigerant circuit (1) of the refrigeration system (R). The freezer (75) is installed in a physics and chemistry laboratory or the like, and (74) is a main body that internally forms a storage chamber (76) with an upper opening, the upper opening of which is pivotable at the rear side. It is openably and closably closed by a supported heat insulating door (77). A machine room (78) for accommodating and installing the temperature controller (61), the electric compressors (4), (10), etc. is formed on the side of the main body (74), and inside the storage room (76) is formed on the front surface. The temperature recorder (79) that senses the temperature of the sensor and records the change over time on the recording paper, and the publicly known alarm device (80) and temperature controller (61) that issues an alarm when the storage room (76) has an abnormally high temperature. A setting change knob (81) is provided. Further, (82) is a ventilation slit.

FIG. 5 is a side sectional view of the main body (74). (8
3) is a steel outer box with an upper opening, (84) is an aluminum inner box with an upper opening, and the inner box (84) is an outer box (83).
A double heat insulating layer, which is built into the inside of the box (83) (84) and has a box-like outer heat insulating material (85) and an inner heat insulating material (86) that are open upwards, is formed independently of each other. Box (83)
The opening edges of (84) are connected by a breaker (87). The evaporation pipe (47) is arranged in a heat conductive manner on the outer surface of the inner box (84) and is embedded in the inner heat insulating material (86), and the inner edge of the opening of the outer box (76) is exposed to dew. A protection pipe (6) is arranged in a heat-conducting manner. Even if the inner heat insulating material (86) contracts due to the cooling action of the evaporation pipe (47), the inner heat insulating material (86) is completely placed by being placed in the outer heat insulating material (85). The outer heat insulating material (85) is not affected in any way, so that the heat insulating material is not cracked and sufficient heat insulating performance is maintained. An opening (88) is formed on the back surface of the outer box (83), and a cutout (89) is also formed in the outer heat insulating material (85) correspondingly.
Is formed in the notch (89), the cascade capacitors (25A) (25B), etc., which are molded from the opening (88) by a heat insulating material (90) as described later, are housed in the cover plate (91). Covered. (92) is an inner cover made of Styrofoam, (93) is a gasket on the inner peripheral surface of the heat insulation door (77), (9)
4) is a transport caster.

Next, FIG. 6 shows a specific configuration of the refrigerant circuit (1) of the refrigeration system (R), and the same reference numerals as those in FIG. 1 are the same. The auxiliary condenser (17) of the low temperature side refrigerant circuit (3) is different from the high temperature side refrigerant circuit (2) with respect to the air suction type blower (9).
It is arranged on the windward side of the condenser (8) and is cooled at the same time. The first and second evaporators (14A) and (14B) are in the shape of a hollow tank, and the first and second condensing pipes (23A) are spirally wound inside the tank from above.
(23B) are inserted respectively. (66A) is a tubular body for fixing the low temperature starting thermostat (66) welded and fixed to the accumulator (15). (96) is composed of intermediate heat exchangers (32) (42) (44), etc., which will be described later, and the heat insulating material (9
It shows the intermediate heat exchanger part molded into a box shape by 7). The evaporation pipe (47) is fixed to the outer surface of the inner box (84) in advance in a meandering shape with an aluminum tape or an adhesive, but in order to reduce the temperature distribution in each part of the storage chamber (76) as much as possible, The order in which the refrigerant flows is
The inner box (84) is arranged so as to go from the upper part to the lower part and finally to the bottom.

FIG. 7 shows the structure of the intermediate heat exchanger section (96). The portions surrounded by the dotted lines are the first, second and third intermediate heat exchangers (32) (4
2) (44), second gas-liquid separator (33), dryer (39) (4
5) An intermediate heat exchanger section (96) including a pressure reducer (40) and an accumulator (49). Each intermediate heat exchanger (32)
(42) (44) are outer pipes (98) (99) (10
0) spirally wound in multiple stages and flattened are superposed on each other, and the insides of the gas phase pipes (30) (4)
3) has a spiral double pipe structure that passes through as an inner pipe, and the part (A) in the figure is the first intermediate heat exchanger (3
2), (B) part is the second intermediate heat exchanger (42),
The portion (C) serves as the third intermediate heat exchanger (44). Inside this spiral, the second gas-liquid separator (33) and dryer (39)
(45), the decompressor (40) and the accumulator (49) are housed to reduce the dead space and reduce the size.

Next, the configuration will be described. (101) is a pipe connecting the dryer (28) and the first gas-liquid separator (29). After the gas-phase pipe (30) that goes upward from the first gas-liquid separator (29) enters the outer pipe (98) through the sealed inlet (IN ₁ ) and spirally circulates inside , Exits from the outlet (OUT ₁ ) and enters the second gas-liquid separator (33). The gaseous refrigerant flowing down in the vapor-phase pipe (30) passes through the vapor-phase pipe (30) and the outer pipe (9
8) It is condensed by the low temperature refrigerant which rises the interval. The gas-phase pipe (43) from the second gas-liquid separator (33) enters the outer pipe (99) through the inlet (IN ₂ ). The liquid refrigerant separated by the first gas-liquid separator (29) is decompressed by the pressure reducer (36), and then the outlet (OUT ₁ ) of the outer pipe (98) and the inlet (IN ₂ ) of (99). Contributes to the condensation of the gaseous refrigerant in the gas-phase pipe (30) together with the refrigerant that has flowed into the communication pipe (102) connecting the two and evaporates in the outer pipe (98) and returns from the evaporation pipe (47). To do. Gas phase piping (43) inside the outer piping (99)
Exits from the outlet (OUT ₂ ), enters the outer pipe (100) from the inlet (IN ₃ ) again, spirals around, and exits from the outlet (OUT ₃ ). The outer pipes of the above outlets and inlets are sealed. The liquid refrigerant separated by the second gas-liquid separator (33) is reduced in pressure by the pressure reducer (40) through the dryer (39) provided in heat exchange with the outer pipe (100), and then the outer pipe. Communication pipe (10) that connects the (99) outlet (OUT ₂ ) and (100) inlet (IN ₃ )
3) Contributes to the condensation of the gaseous refrigerant in the gas-phase pipe (43) together with the refrigerant returned from the evaporation pipe (47) by flowing in the middle and evaporating in the outer pipe (99). Gas phase piping (4
3) Refrigerant R50 flowing down the inside is further condensed when passing through the inside of the outer pipe (100) and almost liquefied, and the outer pipe (100)
And a decompressor (46) via a dryer (45) provided in a heat exchange manner. (105) is a pipe connected to the outlet side of the evaporation pipe (47), which is connected to the outlet (OUT ₃ ) of the outer pipe (100) and communicates with the space outside the vapor phase pipe (43). Also (106)
Is the gas phase piping (3) at the inlet (IN ₁ ) of the outer piping (98).
0) A pipe that connects the outer space and the accumulator (49). That is, the return refrigerant from the evaporation pipe (47) flows into the space between the outer pipe (100) and the gas phase pipe (43) from the pipe (105), rises there, and flows down in the gas phase pipe (43). The incoming refrigerant is condensed and the communication pipe (103) is used to reduce the pressure (40).
Combined with the refrigerant from the outside pipe (99) and vapor phase pipe (43)
Of the gas phase pipe (43) to condense the refrigerant in the vapor phase pipe (43), and further joins with the refrigerant from the pressure reducer (36) in the communication pipe (102) to form the outside pipe (98). After flowing into the space between the gas phase pipe (30) and the gas phase pipe (30) and ascending there, the refrigerant in the gas phase pipe (30) is condensed, and then passes through the pipe (106) to reach the accumulator (49). 108) Intake side heat exchanger (2
Inflow into 4). As described above, vapor phase piping (30) or (4
3) The flow of the refrigerant flowing down and the vapor pipe (30) or vapor phase pipe (30) or (43) and the outer pipe (100) (99)
The flows of the refrigerant that rises between (98) are countercurrent to each other.

Next, FIG. 8 shows a rear perspective view of the freezer (75), and a procedure for incorporating the freezer (R) will be described. An opening (110) is formed on the back surface of the outer box (83) in parallel with the opening (88), and a corresponding notch (111) is formed in the outer heat insulating material (85). Inside the insulation (90) is a cascade capacitor (25
The suction side heat exchangers (22) and (24), the accumulator (15) and the dryer (28) are molded together with A) and 25B. The heat insulation materials (90) and (97) are molded by placing the molded parts in a resin bag, placing it in a box-shaped foam mold, and foam-filling the urethane insulation material in the bag to mold it. To do. The decompressor (46) and the pipe (105) are extended from the heat insulating material (97), and the lead-out parts (112) (11) at the inner part of the notch (111).
It is connected to the evaporation pipe (47) derived from 2) by welding. Pipes such as a decompressor (13) extended from the heat insulating material (90) are connected by welding to a pipe led out from the wall surface of the cutout (89) on the machine room (78) side. The first gas-liquid separator (29) and the dryer (35) are located outside the heat insulating material (90), and the heat insulating material (9
Notches (89) (1) with pipes (0) and (97) connected to each other
11), and the gap is filled with glass wool, etc., and then the cover plate (91) covers the notches (89) and (111) to complete the installation. Further, the electric compressors (4) and (10), the condenser (8), the blower (9), the expansion tank (51), and the like are installed in advance in the machine room (78), whereby the freezer (75) is Complete.

The ideal operating conditions of the refrigeration system (R) of the present invention have been described above, but the final stage, that is, the third intermediate heat exchanger (44).
The area from to the evaporation pipe (47) is -120 ° C as described above.
Since it is cooled to an extremely low temperature such as -150 ° C, the liquid refrigerant that has passed through the third intermediate heat exchanger (44) is decompressed due to heat invasion from the surroundings even if the heat insulation is strictly performed as in the above-mentioned configuration. Attempts to evaporate in the vessel (46). Here, the uncondensed refrigerant from the second gas-liquid separator (33) contains some R14 refrigerant, but most of it is R50 refrigerant. FIG. 9 shows the relationship between the R50 refrigerant pressure and the evaporation temperature. As described above, when the R50 refrigerant vaporizes in the pressure reducer (46), the inside diameter of the pressure reducer (46) is very small (usually 1 mm or less).
The inside of 6) is immediately filled with gas refrigerant, the passage resistance becomes excessive and the liquid refrigerant cannot flow, the temperature of the evaporation pipe (47) rises, and the storage chamber (76) is not cooled sufficiently. Will end up.

However, the obstruction of the flow of the liquid refrigerant in the pressure reducer (46)
Since the pressure rises before entering the pressure reducer (46), the evaporation temperature of the R50 refrigerant also rises as shown in FIG. 9, and as a result, evaporation inside the pressure reducer (46) ceases.
The liquid refrigerant is again supplied to the evaporation pipe (47), and normal cooling is performed. However, if the temperature is lowered by this, evaporation in the decompressor (46) starts again as described above, and this is repeated. In such a situation, not only is there insufficient cooling in the storage room (76),
The load applied to the electric compressor (10) fluctuates drastically, which not only shortens the life of the electric compressor (10) but also increases noise. Therefore, in the present application, the dryer (45) is arranged in the third intermediate heat exchanger (44) in a heat-exchange manner, and the R50 refrigerant that has passed through the third intermediate heat exchanger (44) is cooled again, It suppresses the temperature rise due to heat intrusion from the. This prevents the refrigerant from evaporating in the decompressor (46) and eliminates the aforementioned insufficient cooling.

Further, such an abnormal situation also occurs when the amount of the refrigerant filled in the low temperature side refrigerant circuit (3) is not appropriate. That is, FIG. 9 shows the time transition of the temperature in the storage chamber (76) after the refrigeration system (R) is powered on, and (L ₁ ) shows the case where the refrigerant charging amount is appropriate (L ₂ ) Indicates the case where the refrigerant charging amount is excessive, and (L ₃ ) indicates the case where the refrigerant charging amount is excessive. Further, FIG. 10 shows the temperature (L ₂ ) in the storage chamber (76) when the refrigerant charge amount is excessive near the ultimate temperature (L ₂ ) and the temperature when it is too low (L ₃ ). (L ₄ ) is the temperature of the refrigerant flowing into the pressure reducer (46) when the refrigerant charge is excessive, that is, the temperature of the inlet (P ₁ ) of the pressure reducer (46) in FIG. ₁ , and (L ₅ ) is the same. If the temperature is too high, the temperature of the refrigerant after leaving the pressure reducer (46), that is, the temperature of the inlet portion (P ₂ ) of the evaporation pipe (47) in FIG.
(L ₆ ) is the temperature of the inlet (P ₁ ) of the pressure reducer (46) when the refrigerant filling amount is too small, and (L ₇ ) is the inlet (P ₂ ) of the evaporation pipe (47) when the amount is too small. ) Indicates the temperature.

When the refrigerant charge amount is excessive, the speed at which the temperature of the storage chamber (76) decreases from the start of the cooling operation is faster than when the charge amount is normal. However, since the amount of the liquid refrigerant supplied to the evaporation pipe (47) is too large, when the temperature in the storage chamber (76) drops to the ultimate temperature, a large amount of liquid refrigerant cannot be evaporated in the evaporation pipe (47). The liquid refrigerant is the third intermediate heat exchanger (4
It flows into 4) and evaporates there, and the temperature of the third intermediate heat exchanger (44) is cooled to a value equivalent to that of the evaporation pipe (47). As a result, the temperature of the inlet part (P ₁ ) of the decompressor (46) also decreases, but the temperature difference from the surroundings increases, so the amount of heat intrusion from the surroundings increases and the evaporation of the liquid refrigerant is promoted. Become. As a result, the evaporation of the liquid refrigerant in the decompressor (46) starts, the flow of the liquid refrigerant is obstructed by the pressure increase in the decompressor (46), and the supply of the liquid refrigerant to the evaporation pipe (47) is reduced, so that the inlet The temperature of the part (P ₂ ) also rises. As a result, the temperature in the storage room (76) also rises. That is, as shown in the Mollier diagram of Fig. 13, when the ideal refrigeration cycle in which the final stage refrigerant R50 is completely liquefied in the evaporation pipe (47) is → → →, the amount of the refrigerant to be charged is If the amount is excessive, the liquid refrigerant will be supercooled in the intermediate heat exchanger (44). Therefore, the pressure difference Pd of the refrigeration cycle from Pd ₁ to Pd ₂ by the amount of this liquid, that is, Pd ₁ −Pd ₂ It will decrease by the amount. As a result, the refrigeration cycle is → → →
Therefore, in the pressure reducer (46), the flow of the liquid refrigerant deteriorates as much as the pressure difference Pd decreases, and the supply of the liquid refrigerant to the evaporation pipe (47) decreases. This phenomenon occurs in the intermediate heat exchanger (4
The larger the amount of supercooling in 4), the greater the amount of liquid, which becomes more noticeable. That is, the greater the supercooling, the greater the decrease in the pressure difference Pd. Incidentally, the above-mentioned phenomenon is particularly remarkable when a capillary tube or the like having a fixed throttle amount is used for the decompressor (46). When the flow of the liquid refrigerant in the pressure reducer (46) is obstructed, the pressure of the liquid refrigerant rises as described above, the evaporation temperature rises and the liquid refrigerant does not evaporate, and the pressure reducer (46) again.
After that, normal cooling is performed, but if the liquid refrigerant remains in the evaporation pipe (47) due to the subsequent cooling, the same situation is repeated again. That is, in Fig. 11 (L ₂ )
Like (L ₄ ) and (L ₅ ), each temperature pulsates and becomes unstable. Here, the temperature in the storage room (76) is slightly delayed. In such a situation, as shown in FIG. 9, the temperature in the storage chamber (76) periodically exceeds the normal state (L ₁ ) to cause insufficient cooling, and the vibration noise of the electric compressor (10) increases. Causes abnormal wear and tear.

In such a situation, the temperature of the refrigerant flowing into the pressure reducer (46) approaches the temperature of the refrigerant after leaving the pressure reducer (46), that is, the pressure reducer (46).
The temperature of the inlet part (P ₁ ) drops and approaches the temperature of the inlet part (P ₂ ) of the evaporation pipe (47) too much.
It is confirmed experimentally that the following is true. Therefore, in the present invention, the refrigerant is charged so that the temperature difference between points (P ₁ ) and (P ₂ ) is larger than 10 ° C. This prevents the refrigerant from being overfilled, prevents the above pulsation, and enables stable cooling operation. Along with this, a dryer (45) is provided in the third intermediate heat exchanger (44) for heat exchange to reduce the influence of heat intrusion, so that the temperature is further stabilized.

Next, when the refrigerant charge amount is too small, the cooling rate is naturally slow as shown by (L ₃ ) in FIG. Further, although a small amount of the refrigerant circulates in the low temperature side refrigerant circuit (3), a small amount of the liquid refrigerant flows into the evaporation pipe (47) from the pressure reducer (46) and immediately evaporates, whereby As shown in Fig. 10 (L ₇ ), the temperature of the inlet part (P ₂ ) of the evaporation pipe (47) drops, but since the amount of liquid refrigerant is small, evaporation ends immediately,
After that, the gaseous refrigerant only flows from the evaporation pipe (47) to the third intermediate heat exchanger (44). As a result, the inside of the storage chamber (76) becomes insufficiently cooled and the temperature rises,
The temperature of the third intermediate heat exchanger (44) rises as it stabilizes at a high value such as (L ₃ ), so that the refrigerant after heat exchange with it passes through the inlet of the pressure reducer (46) ( The temperature at (P ₁ ) also rises as at (L ₆ ), and the temperature difference between points (P ₁ ) and (P ₂ ) becomes very large.

Here, in the refrigerating apparatus (R) of the present invention, the temperature (−50 ° C.) of the cascade condenser (25A) (25B) and the evaporation pipe (47)
Temperature difference (-150 ℃) 100 ℃ decompressor (36) (40)
(46) is created stepwise by creating a temperature difference before and after. That is, each pressure reducer (36) (40) (4
Even if the temperature difference between before and after 6) is evenly divided, the temperature difference is usually set to 33 ° C as the temperature gets lower to reduce the load even if it is divided evenly. Vessel (46) inlet (P ₁ ) and evaporation pipe (47)
It can be said that it is abnormal when the temperature difference with the inlet portion (P ₂ ) is large near the reached temperature, and the cause is that the refrigerant charge amount is too small as described above. Therefore, in the present invention, by filling the refrigerant so that the temperature difference between points (P ₁ ) and (P ₂ ) becomes smaller than 33 ° C., the insufficient cooling due to the insufficient filling of the refrigerant is eliminated.

Summarizing the above, the pressure reducer (46) depends on the temperature of the inlet (P ₁ ) of the pressure reducer (46) and the temperature of the inlet (P ₂ ) of the evaporation pipe (47).
The difference between the temperature of the refrigerant flowing in and the temperature of the refrigerant after it is measured, and the difference is greater than 10 ° C near the reached temperature, and the cascade condensers (25A) (25B) and the evaporation pipe ( By filling the refrigerant so that the temperature difference of 47) is divided by the number of pressure reducers (36) (40) (46), that is, within the range smaller than 33 ° C, an appropriate amount of refrigerant can be filled. .

Here, the refrigeration system (R) is also affected by the ambient temperature in which it is installed. That is, assuming that the ambient temperature is high and the refrigerant is filled so as to exert sufficient cooling capacity, when the ambient temperature becomes low, the cascade condensers (25A) (25B) and each intermediate heat exchanger (32 ) (42)
Since the temperature of (44) also drops, in addition to the refrigerant to be condensed in each intermediate heat exchanger, a part of the refrigerant to be condensed in the intermediate heat exchanger in the subsequent stage is also condensed, and the electric compressor ( Since it returns to 10), the amount of R50 refrigerant that finally flows into the evaporation pipe (47) decreases, resulting in insufficient cooling. When the refrigerant charge amount is increased in order to eliminate this, the pulsation as described above occurs this time in a state where the ambient temperature is high.

On the other hand, as in the present invention, by filling the refrigerant so that the temperature difference between the points (P ₁ ) and (P ₂ ) is larger than 10 ° C and smaller than 33 ° C, the temperature can be changed from high to low. And stable cooling capacity can be demonstrated.

Here, the self-recording temperature recorder (79) records the temperature in the storage room (76), and is one of the important components in this type of freezer. By the way, recorders (79) are generally
As shown in the figure, it is composed of a well-known Archimedes spiral Bourdon tube (120) and a recording sheet (not shown) that is automatically moved with time. In Figure 11 (121)
Is a temperature-sensing section arranged to sense the temperature in the storage chamber (76), and the Bourdon tube (120) and the temperature-sensing section (121) are connected by a thin tube (122) for communication. A drive shaft (123) is erected and fixed at the center (0) of the spiral of the Bourdon tube (120), and a pointer (124) for recording is attached to the tip of the drive shaft (123). The Bourdon tube (120) is hollow inside, and a temperature sensitive substance such as ethyl alcohol or normal propyl alcohol is enclosed in a liquid state inside. The Bourdon tube (120) is deformed by the change of the internal pressure due to the temperature change of the temperature sensing part (121), and rotates the drive shaft (123) about the axial direction. The rotation angle (θ) is It is known to be proportional to the pressure change in the Bourdon tube (120), and thereby the temperature in the storage chamber (76) is converted to the position of the pointer (124) and recorded.

By the way, the general temperature-sensitive substances such as ethyl alcohol and normal propyl alcohol are used at around -80 ° C, for example, and they are frozen at an extremely low temperature such as -150 ° C, which is the object of the present invention, and a temperature recorder. Cannot be used as Then, as a result of earnest research, in the present invention, by encapsulating 2-methylpentane (isohexane) as a temperature-sensitive substance, it was achieved to record the temperature at an ultralow temperature such as -150 ° C. FIG. 12 shows the relationship between the temperature (T) around the temperature sensing part (121) and the pressure (P) inside the Bourdon tube (120) when 2-methylpentane is enclosed in the Bourdon tube (120). As is clear from the figure, the pressure (P) is -150 ° C.
Is approximately proportional to temperature (T) in the temperature range from + 50 ° C. Here, since the rotation angle (θ) of the pointer (124) is proportional to the pressure (P) as described above, it is also substantially proportional to the temperature (T), whereby the storage chamber (76) is in the range of −150 ° C. to + 50 ° C. The temperature inside can be recorded.

In the embodiment, two independent refrigerant circuits are connected in cascade, and the low temperature side refrigerant circuit is applied to a mixed refrigerant refrigeration system, but the invention is not limited to this, and a mixed refrigerant refrigeration system using a single refrigerant circuit is used. The present application is also effective.

(G) Effect of the Invention According to the present invention, in a refrigerating apparatus including a refrigerant circuit using a non-azeotropic mixed refrigerant, the temperature of the refrigerant flowing into the final stage pressure reducer is the temperature of the refrigerant after leaving the temperature. It is possible to fill an appropriate amount of the refrigerant by setting the difference in the temperature range within a proper range, that is, smaller than a value obtained by dividing the temperature difference between the condenser and the evaporator by the number of pressure reducers and larger than 10 ° C. Therefore, the pulsation of the temperature of the space to be cooled that occurs when the filling amount is excessive, and the insufficient cooling that occurs when the filling amount is insufficient, and a cooling device that exhibits a stable capacity that is not affected by the ambient temperature. Can be configured.

[Brief description of drawings]

1 to 9 show an embodiment of the present invention, FIG. 1 is a refrigerant circuit diagram of a refrigeration system, FIG. 2 is an electric circuit diagram for the same control, and FIG. 3 is a timing for explaining the operation of the refrigeration system. chart,
FIG. 4 is a perspective view of a freezer, FIG. 5 is a side sectional view of a freezer main body, FIG. 6 is a view showing a specific configuration of a refrigerant circuit of a refrigerating apparatus, FIG. 7 is a perspective view of an intermediate heat exchanger part, FIG. 8 is a rear perspective view of the freezer, FIG. 9 is a diagram showing a time transition after the power is turned on in the storage room, and FIG. 10 is an reached temperature when the refrigerant filling amount in the low temperature side refrigerant circuit is excessive or insufficient. Figures showing the temperature of the storage room in the vicinity, FIGS. 11 and 12 show an embodiment of the self-recording temperature recorder, FIG. 11 is a perspective view of a Bourdon tube constituting the self-recording temperature recorder, and FIG. 12 is FIG. 13 is a diagram showing the relationship between the internal pressure of a Bourdon tube in which 2-methylpentane is sealed and the temperature of the temperature sensing part, and FIG. 13 is a Mollier diagram showing the case where the amount of refrigerant charged into the low temperature side refrigerant circuit is excessive. (R) ... Refrigerator, (2) ... High temperature side refrigerant circuit,
(3) …… Low temperature side refrigerant circuit, (4) (10) …… Electric compressor, (25A) (25B) …… Cascade condenser, (32)
(42) (44) …… Intermediate heat exchanger, (36) (40) (46)…
… Decompressor, (47) …… Evaporation pipe.

Claims (1)

[Claims] 1. A compressor, a condenser, an evaporator, a plurality of intermediate heat exchangers connected in series so as to circulate the return refrigerant from the evaporator, and a plurality of pressure reducers, and a plurality of non-coexisting types. Containing a boiling mixed refrigerant, condensing the condensed refrigerant in the refrigerant that has passed through the condenser to the intermediate heat exchanger via the pressure reducer, by cooling the uncondensed refrigerant in the refrigerant there, sequentially. In a refrigerating apparatus for obtaining a cryogenic temperature by condensing a refrigerant having a lower boiling point and allowing a refrigerant having the lowest boiling point to flow into the evaporator through a decompressor at the final stage, the amount of the non-azeotropic mixed refrigerant enclosed is The difference between the temperature of the refrigerant flowing into the final stage pressure reducer and the temperature of the refrigerant after leaving it is smaller than the value obtained by dividing the temperature difference between the condenser and the evaporator by the number of the pressure reducers and is larger than 10 ° C. Refrigerating device characterized by setting the amount so as to fall within the range.