JP2640051B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system using a compressor, and more particularly to a refrigeration system for obtaining an extremely low temperature of -60.degree.

[0002]

2. Description of the Related Art Conventionally, this type of refrigerating apparatus is disclosed in, for example, Japanese Utility Model Publication No. 58-23101. In other words, the refrigerant circuit on the high temperature side and the refrigerant circuit on the low temperature side are respectively constituted by two independent refrigerant closed circuits, and the heat exchanger is constituted by the evaporator of the high temperature side refrigerant circuit and the condenser of the low temperature side refrigerant circuit. The refrigerant in the low-temperature side refrigerant circuit is condensed by the evaporation of the refrigerant in the refrigerant circuit. As a result, a refrigerant having a lower boiling point (evaporation temperature) can be used in the low-temperature side refrigerant circuit, so that an extremely low temperature can be obtained by the evaporator of the low-temperature side refrigerant circuit.

[0003] In such a dual refrigerating system, a low temperature of about -80 ° C is usually obtained in the evaporator of the low-temperature side refrigerant circuit. To obtain a lower temperature, for example, -130 ° C, a refrigerant circuit configuration is required. And it is necessary to make various improvements to the composition of the charged refrigerant.

[0004] The present applicant has filed a Japanese Patent Application No. Sho 61
In the specification of -91599 and the like, the latter method described above, that is, a method of devising the composition of the charged refrigerant, at -130 ° C
Ultra low temperature was realized.

More specifically, R500 and R502 are sealed in the high-temperature side refrigerant circuit, and R13B1 (bromotrifluoromethane) and R503 are sealed in the low-temperature side refrigerant circuit.

According to this, an ultra-low temperature of -130 ° C. can be achieved in the evaporator even with a conventional compressor, but the refrigerant (R50) flowing into the decompressor immediately before the evaporator also has an ultra-low temperature of -100 ° C. or less. There is a risk that the moisture in the refrigerant freezes in the pressure reducer or in a nearby pipe, causing clogging.

For this reason, in the conventional apparatus, a heater is provided in the pipe near the decompressor, and this heater is operated by a timer.
The compressor is stopped every two hours and the compressor is stopped at the same time.

[0008]

However, according to the above arrangement, the heater is energized periodically regardless of the start / stop of the compressor, so that, for example, as shown in FIG. If it is necessary to operate the compressor and the timer times out and the heater is energized and the compressor is forcibly stopped, the temperature inside the refrigerator exceeds the upper limit of the set temperature and rises steadily. There was a problem of adversely affecting things. (FIG. 4 shows the case where the timer times out at the upper limit value of the set temperature.) The present invention has been made in view of such a point, and the power supply to the icing prevention heater is optimally controlled in relation to the temperature in the refrigerator. It is an object of the present invention to surely suppress the rise in the internal temperature and to store stored items (cells, specimens, etc.) for a long period of time.

[0009]

According to the present invention, there is provided a refrigeration system comprising a compressor, a condenser, a decompression device, and an evaporator connected to a pipe, and a heating means for heating the decompression device or a pipe near the decompression device. , A timer element is provided, and when the compressor is stopped within a predetermined time by the timer element, the heating means is energized simultaneously with the stop of the compressor, while the compressor is not stopped within a predetermined time by the timer element. Is configured to forcibly stop the compressor and energize the heating means.

[0010]

According to the refrigerating apparatus of the present invention, for example, after the operation of the refrigerating apparatus, if the compressor is stopped within a predetermined time by the timer element, that is, the internal temperature of the refrigerator decreases to the lower limit of the set temperature. At the same time, the heater can be energized simultaneously with the stoppage of the compressor, and the temperature rise due to the heater energization is always set to the lower limit, thereby suppressing the rise in the internal temperature and preventing clogging due to icing in the piping of the pressure reducing device.

Further, even if the compressor is not stopped within a predetermined time by the timer element, the heater can be energized as in the prior art, so that clogging due to icing in the piping of the pressure reducing device can be reliably prevented. .

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a refrigerant circuit (1) of a refrigeration apparatus of the present invention. The refrigerant circuit (1) is composed of an independent 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.

(4) an electric compressor using a one-phase or three-phase AC power source constituting the high-temperature side refrigerant circuit (2);
The discharge side pipe (4D) of the electric compressor (4) is connected to the auxiliary condenser (5), and the auxiliary condenser (5) is further connected to the dew-prevention pipe (6) for heating the opening edge of the storage compartment of the freezer. Then, after being connected to the oil cooler (7) of the electric compressor (4), it is connected to the condenser (8). (9) is a blower for cooling the condenser (8). The refrigerant pipe exiting the condenser (8) passes through a dryer (12), and then passes through a decompressor (13) to an evaporator (1) as an evaporator part constituting an evaporator.
4) The accumulator (15) as a coolant reservoir through
Connected to.

The pipe coming out of the accumulator (15) is connected to the suction pipe (4S) of the electric compressor (4).

In the high temperature side refrigerant circuit (2), a refrigerant chlorodifluoromethane (R22) having a different boiling point and 1-chloro-
1,1-difluoroethane (R142b) and dichlorofluoromethane (R21) are filled, and the composition is, for example, 70% by weight of R22, 25% by weight of R142b,
21 is 5% by weight.

The high-temperature gaseous refrigerant discharged from the electric compressor (4) is supplied to an auxiliary condenser (5), an anti-dew pipe (6),
After being condensed by the oil cooler (7) and the condenser (8) and radiated and liquefied, the moisture contained therein is removed by the dryer (12), the pressure is reduced by the pressure reducer (13), and the pressure is reduced by the evaporator (14) one after another. And the refrigerant R22 and R142b evaporate, absorb the heat of vaporization from the surroundings, cool the evaporator (14), and return to the electric compressor (4) via the accumulator (15) as a refrigerant reservoir.

At this time, the capacity of the electric compressor (4) is, for example, 1.5 HP, and the ultimate temperature of the evaporator (14) during operation is -25 ° C to -35 ° C. Under such a low temperature, R21 in the refrigerant has a boiling point of 8.95 ° C., so that it does not evaporate in the evaporator (14) and remains in a liquid state. Therefore, it hardly contributes to cooling. A) the function of returning the lubricating oil or the mixed water that could not be completely absorbed by the dryer (12) to the electric compressor (4) in a state of being dissolved therein; and the function of the liquid refrigerant in the electric compressor (4). The function of reducing the temperature of the compressor (4) by the evaporation in the compressor.

The discharge side pipe (10D) of the electric compressor (10) constituting the low temperature side refrigerant circuit (3) is an oil separator (18).
Connected to. From the oil separator (18), the electric compressor (1
An oil return pipe (19) returning to 0) is connected.

The refrigerant pipe coming out of the oil separator (18) is connected to a condensing pipe (23) as a high-pressure pipe inserted into the evaporator (14).

The evaporator (14) and the condensing pipe (23)
It constitutes a cascade capacitor (25).

The discharge pipe of the condensing pipe (23) is connected to a first gas-liquid separator (29) via a dryer (28).

The gas-phase pipe (3) coming out of the gas-liquid separator (29)
0) passes through the first intermediate heat exchanger (32) and is connected to the second gas-liquid separator (33).

The liquid phase pipe (3) coming out of the gas-liquid separator (29)
4) is connected to the first intermediate heat exchanger (32) via the depressurizer (36) after passing through the dryer (35).

The liquid phase pipe (3) coming out of the gas-liquid separator (33)
8) is connected to a second intermediate heat exchanger (42) via a depressurizer (40) after passing through a dryer (39).

The gas-phase pipe (4) exiting from the gas-liquid separator (33)
3) passes through the second intermediate heat exchanger (42), then passes through the third intermediate heat exchanger (44), and is dried (45).
Through a pressure reducer (46).

The decompressor (46) is connected to an evaporator pipe (47) as an evaporator.
Is connected to the intermediate heat exchanger (44).

The third intermediate heat exchanger (44) is connected to the second (4)
After being successively connected to 2) and the first intermediate heat exchanger (32), it is connected to the suction side pipe (10S) of the electric compressor (10).

Here, heaters (53) and (54) for preventing icing are attached to the inlet and outlet pipes of the pressure reducer (46).

The energization of the heaters (53) and (54) is controlled by a microcomputer (55).

That is, the microcomputer (55) has a first timer element (56) which generates a signal by time-up every 18 hours, and a first timer element (56).
Has a built-in second timer element (57) for accumulating 6 hours after the time is up, and based on signals from these timer elements (56) (57), the compressor (4) (1)
0) and the heaters (53) and (54).

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

The low-temperature side refrigerant circuit (3) has six different boiling points.
Various types of mixed refrigerants are enclosed.

That is, R21 (dichlorofluoromethane), R22 (chlorodifluoromethane), R23 (trifluoromethane), R14 (carbon tetrafluoride), R50
A mixed refrigerant composed of (methane) and R740 (argon) is sealed in a premixed state.

The composition of each refrigerant is, for example, R21 is 12% by weight, R22 is 38% by weight, R23 is 16% by weight, R14 is R14.
23% by weight, R50 5% by weight, R740 6% by weight
It is.

R50 is methane, and there is a danger of explosion due to the combination with oxygen. However, the danger of explosion is eliminated by mixing with the above ratio of each refrigerant. Therefore, even if a leakage accident of the mixed refrigerant occurs, an explosion accident does not occur.

Next, the circulation of the low-temperature refrigerant will be described. The high-temperature, high-pressure gaseous mixed refrigerant discharged from the electric compressor (10) is mixed with the refrigerant in the oil separator (18). Most of the lubricating oil of (10) is returned to the electric compressor (10) by the oil return pipe (19), and the refrigerant itself is cooled by the evaporator (14) by the cascade condenser (25) and is contained in the mixed refrigerant. Some refrigerants with high boiling points (R21, R22, R2
3) is condensed and liquefied.

The mixed refrigerant flowing out of the condensing pipe (23) flows into the gas-liquid separator (29) via the dryer (28). At this point, R14, R50 and R740 in the mixed refrigerant have a very low boiling point and are not condensed yet and are in a gaseous state, and only a part of R21, R22 and R23 is condensed and liquefied. And R740 are gas phase piping (3
At 0), R21, R22 and R23 are separated into a liquid phase pipe (34).

The refrigerant mixture flowing into the gas phase pipe (30) exchanges heat with the first intermediate heat exchanger (32) and is condensed, and then reaches the gas-liquid separator (33).

Here, the low-temperature refrigerant returning from the evaporating pipe (47) flows into the first intermediate heat exchanger (32), and the liquid refrigerant flowing into the liquid phase pipe (34) is further dried ( After the pressure is reduced to the pressure reducer (36) through the pressure reducer (35), it flows into the first intermediate heat exchanger (32) and evaporates there, thereby contributing to cooling. Therefore, uncondensed R14, R50, and R7.
As a result of cooling some of R40 and R23, the intermediate temperature of the first intermediate heat exchanger (32) is about -56.4 ° C. Therefore, R in the mixed refrigerant passing through the gas phase pipe (30)
23 is completely condensed and liquefied, and the second gas-liquid separator (33)
Shunted. R14, R50 and R740 are still in a gaseous state because of their lower boiling points.

In the second intermediate heat exchanger (42), R23 split by the second gas-liquid separator (33) is supplied to the dryer (3).
After the water is removed in 9) and the pressure is reduced in the pressure reducer (40), the gas flows into the second intermediate heat exchanger (42), and the gas phase piping together with the low-temperature refrigerant returned from the evaporation pipe (47). Cool R14, R50 and R740 in (43),
Among them, R14 having the highest evaporation temperature is condensed.

As a result, the intermediate temperature of the second intermediate heat exchanger (42) becomes -84.5 ° C.

The gas-phase pipe (43) passing through the second intermediate heat exchanger (42) is subsequently connected to the third intermediate heat exchanger (4).
Go through 4).

Here, the refrigerant immediately after leaving the evaporator (47) is fed back to the third intermediate heat exchanger (44). According to the experiment, the third intermediate heat exchanger (44) Intermediate temperature is-
The temperature near the inlet reaches 109.8 ° C, which is considerably lower at -151.9 ° C.

For this reason, in the third intermediate heat exchanger (44), a part of R50 and R740 in the gas phase pipe (43) is condensed and these liquefied R14, R50 and R740 are condensed.
After a part of the pressure is reduced by the pressure reducer (46), it flows into the evaporating pipe (47) where it evaporates and cools the surroundings.

According to the experiment, at this time, the evaporating pipe (47)
Was as low as -153.5 ° C.

The evaporating pipe (47) is installed in, for example, a freezer and used for cooling the inside of the freezer.
A 4 ° C. internal temperature was realized.

The refrigerant having exited from the evaporating pipe (47) is supplied to a third intermediate heat exchanger (44), a second intermediate heat exchanger (42),
The refrigerant successively flows into the first intermediate heat exchanger (32), merges with the refrigerant evaporated in each heat exchanger, and returns from the suction side pipe (10S) to the electric compressor (10).

Most of the oil mixed with the refrigerant and discharged from the electric compressor (10) is separated by the oil separator (18) and returned to the compressor (10). What has been discharged from the oil separator (18) together with the refrigerant is R21 and R22 having good oil compatibility.
Is returned to the compressor (10) in a state of being dissolved in the air.

Thus, poor lubrication and locking of the compressor (10) can be prevented.

Further, the compressor (1) is in a state of R21 in a liquid state.
Returning to (0), the refrigerant is evaporated in the compressor (10), so that the discharge temperature of the compressor (10) can be reduced.

In the refrigerating apparatus having such a configuration, the heaters (53) and (54) for preventing icing are energized as shown in the flowchart of FIG.

First, in step S1, it is determined whether or not the first timer element (56) of the microcomputer (55) has accumulated 18 hours.

If 18 hours have not passed, the program returns to the start again.

If 18 hours have elapsed, the process proceeds to step S2, and after 18 hours, it is determined whether or not the compressors (4) and (10) have been stopped by the temperature thermostat (61) in the refrigerator.

When the compressors (4) and (10) are stopped, the process proceeds to step S3, and the heaters (53) and (54) are energized for 6 minutes simultaneously with the stop of the compressors (4) and (10). Then, after the energization ends, the process returns to the start.

If the compressors (4) and (10) are not stopped in step S2, the process proceeds to step S4, and it is determined whether or not the second timer element (57) has accumulated six hours.

If 6 hours have not passed, the process returns to step S2.

When six hours have elapsed, that is, within six hours due to the second timer element (57), the compressor (4) (1
If there is no stop of 0), the process proceeds to step S5,
The compressors (4) and (10) are forcibly stopped, and at the same time, the heaters (53) and (54) are energized for 6 minutes.
Then, after the forced stop of the compressors (4) and (10) is released at the same time as the completion of the energization, the process returns to the start.

According to the refrigeration apparatus configured as described above,
After 18 hours have elapsed by the first timer element (56) of the microcomputer (55), the compressors (4) (10) must be within 6 hours by the second timer element (57).
Is stopped, the compressor (4) as shown in FIG.
Since the heaters (53) and (54) can be energized simultaneously with the stop of (10), the heaters (53) and (5) can be energized.
Power supply to 4) can be performed when the internal temperature is always at the lower limit of the set temperature. (The temperature in the refrigerator is focused on the set temperature between the upper limit value and the lower limit value by controlling the compressors (4) and (10) by the temperature thermometer (61).) As a result, the heaters (53) and (54) The temperature rise H due to energization is also from the lower limit of the set temperature, and the rise in the internal temperature can be suppressed as low as possible.

If the compressors (4) and (10) are not stopped within six hours by the second timer element (57), the compressors (4) and (10) are forcibly stopped as before. And the heaters (53) and (54) were energized, so that the heaters (53) and (5) were at least once a day.
4), the clogging due to icing in the piping of the pressure reducer (46) can be reliably prevented.

In this embodiment, the description has been given of the binary mixed refrigerant circuit which achieves an extremely low temperature of -150 ° C., but the present invention is not limited to this. The same effect can be obtained even when the present invention is implemented in a circuit or a two-stage compression refrigerant circuit.

[0062]

As described above, according to the present invention, after the operation of the refrigeration system, if the compressor is stopped within a predetermined time by the timer element, that is, the internal temperature of the refrigerator has decreased to the lower limit of the set temperature. At the same time, the heater can be energized at the same time as the compressor is stopped, so that energization of the heater is always performed from the lower limit, thereby suppressing the rise in the internal temperature and preventing clogging due to icing in the piping of the pressure reducing device. .

Further, even if the compressor is not stopped within a predetermined time by the timer element, the heater can be energized as in the prior art, so that clogging due to icing in the piping of the pressure reducing device can be reliably prevented. .

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus.

FIG. 2 is a flowchart showing control of a heater.

FIG. 3 is a time chart illustrating control of a heater.

FIG. 4 is a time chart showing control of a conventional heater.

[Description of Signs] 4,10 Electric compressor 25 Cascade condenser 46 Pressure reducer 47 Evaporation pipe 53,54 Heater 55 Microcomputer 56 First timer element 57 Second timer element 61 Temperature thermostat

Claims (1)

(57) [Claims] 1. A refrigerating apparatus in which a compressor, a condenser, a decompression device, and an evaporator are connected by piping, wherein a heating means for heating the decompression device or a pipe near the decompression device is provided, and a timer element is provided. If the compressor is stopped within the predetermined time by the element, the heating means is energized simultaneously with the stop of the compressor, while if the compressor is not stopped within the predetermined time by the timer element, the compressor is forcibly stopped. A refrigeration apparatus characterized in that it is configured to stop and energize a heating means.