JPS62294853A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (a) Industrial Application Field The present invention uses a plurality of refrigerant closed circuits, and cools the condenser of the low temperature side refrigerant circuit by the evaporator of the high temperature side refrigerant circuit. The present invention also relates to a refrigeration system for obtaining an extremely low temperature by evaporating a refrigerant with a low boiling point in an evaporator of a low-temperature side refrigerant circuit.

(b) Prior Art Conventionally, this type of refrigeration system is called a binary refrigeration system, as described in, for example, Japanese Utility Model Publication No. 56-53236.
Two independent refrigerant closed circuits are prepared, and a heat exchanger, ie, a cascade condenser, is configured by the evaporator of the high temperature side refrigerant circuit and the condenser of the low temperature side refrigerant circuit. On the other hand, the low-temperature side refrigerant circuit is filled with a refrigerant with a relatively low boiling point, this refrigerant is condensed in the cascade condenser, and the refrigerant is evaporated in the evaporator of the low-temperature side refrigerant circuit. The structure is such that an extremely low temperature is obtained in the evaporator. Although the configuration as described in the above publication is limited to a final temperature of approximately 185°C, for example, US Pat. The low-temperature side refrigerant circuit is a so-called mixed refrigerant system, and by successively condensing a refrigerant with a lower boiling point with a refrigerant with a higher boiling point, an extremely low temperature is obtained in the final stage evaporator.

(C) 2 Problems to be Solved by the Invention As stated in the above-mentioned publication or specification, the low-temperature side refrigerant circuit is usually filled with a refrigerant with an extremely low boiling point, so the load applied to the electric compressor is also large. If the space to be cooled by the evaporator in the side refrigerant circuit becomes larger, the cooling capacity will need to be increased accordingly, so electric compressors with large capacity and high output will be required on both the high temperature and low temperature sides. This electric compressor consumes a large amount of power when starting up, etc., so it does not require special power supply equipment, and the power consumption is also large.
There was also the problem of increased vibration and noise during operation.

(d) Means for Solving the Problems The present invention has been made to solve these problems, and the present invention will be described in detail below with reference to Examples.

The refrigeration system (RA) has a high temperature side refrigerant circuit (10) and a first low temperature side refrigerant circuit (11), which are independent refrigerant closed circuits.
) and a second low temperature side refrigerant circuit (12). The evaporator of the high temperature side refrigerant circuit (10) has a first evaporator section (1
8A) and a second evaporator part (18B), the condenser (27) of the first low-temperature side refrigerant circuit (11) and the condenser (29) of the second low-temperature side refrigerant circuit (12), respectively. ) constitute a first cascade condenser <28) and a second cascade condenser (30>), respectively.The refrigerant inflow into the second evaporator section (18B) is controlled by a solenoid valve (19), and the refrigerant on the high temperature side is controlled by a solenoid valve (19). When the cooling operation of the circuit (10) starts, the solenoid valve (19) is closed, and then the cooling operation of the first low temperature side refrigerant circuit (11) starts and the evaporator (46) reaches the target temperature of -150°C. When this happens, open the solenoid valve (19),
Thereafter, cooling operation of the second low temperature side refrigerant circuit (12) is started.

(E) Function According to the present invention, since two low-temperature side refrigerant circuits are used, the space to be cooled that should be shared by one refrigerant circuit can be reduced.
The load is reduced, and the capacity of the electric compressor in the low-temperature side refrigerant circuit can be reduced. Further, since the low-temperature side refrigerant circuits start cooling operation one by one, the load applied to the electric compressor of the high-temperature side refrigerant circuit can be distributed, and the capacity can be reduced.

Example Next, an example will be explained with reference to the drawings. Fig. 1 shows a perspective view of a freezer (1) as an example.
) is installed, for example, in a physical and chemical laboratory, etc., and consists of a main body (2) consisting of an insulated box, an upward-opening storage chamber formed inside, and partitioned left and right by insulated partition walls (3). The first storage chamber (4) and the second storage chamber (5) are configured. (
6) is an insulating door that can open and close the upper openings of both storage compartments (4) and (5), and (7) is a refrigeration system (RA) that will be described in detail later.
) is formed on the side by a machine room that houses the components.

FIG. 2 shows a refrigerant circuit of the refrigeration system (RA) of the present application. The refrigeration system (RA) includes a high temperature side refrigerant circuit (10) and a first low temperature side refrigerant circuit (10), each of which constitutes an independent refrigerant closed circuit.
11) and a second low temperature side refrigerant circuit (12). (13) is an electric compressor constituting the high temperature side refrigerant circuit (10), and its discharge side pipe (13D) can be connected to the condenser (14). (15) is a blower for cooling the condenser (14). The refrigerant pipe that exits the condenser (14) passes through the liquid receiver (16) and then splits into two directions at the branch point (Pl), one of which passes through the thermostatic expansion valve (17) and connects to the first evaporator section. (18A), and the other is a solenoid valve (19)
and the second evaporator section 18 via the thermostatic expansion valve (20).
B). This first and second evaporator section (1
8A) (18B) is the evaporator of the high temperature side refrigerant circuit (10). The refrigerant pipe that passes through the first evaporator section (18A) passes through an accumulator (21) as a refrigerant reservoir, and then connects to the electric compressor (22) of the first low temperature side refrigerant circuit (11).
is connected to the oil cooler (23). Furthermore, the refrigerant pipe that has passed through the second evaporator section (18B) can be connected to the oil cooler (26) of the electric compressor (25) of the second low-temperature side refrigerant circuit (12) through a similar accumulator (24). .

The refrigerant pipes that have passed through both oil coolers (23) and (26) meet at a confluence point (P2) and are then connected to the suction side pipe (135) of the electric compressor (13). The temperature sensing part (17A) (20A) of the expansion valve (17) <20> is the accumulator (21)
(24) in a thermally conductive manner and operate to supply the appropriate amount of refrigerant to the evaporator sections (18A) and (18B), respectively.

R502 refrigerant (88% by weight) is used in the high temperature side refrigerant circuit (10).
) and R12 refrigerant (12% by weight) are sealed. now,
To explain the refrigerant circulation assuming that the solenoid valve (19) is open, the high-temperature, high-pressure gaseous refrigerant discharged from the electric compressor (13) is liquefied with heat dissipation in the condenser (14), and then transferred to the liquid receiver ( 16), the pressure is reduced by the expansion valves (17) and (20), and the flow is divided into the respective evaporator parts (18A) (
18B) and evaporate. Here, the first evaporator part (18A>) is the condenser (18A) of the first low temperature side refrigerant circuit (11).
27) and the first cascade condenser (28), and the second evaporator part (18B) constitutes the condenser (29) of the second low temperature side refrigerant circuit (12) and the second cascade condenser (28). 30). Furthermore, each evaporator section (1
8A>(18B>), each cascade condenser (28) (30
) can be cooled down to about -50℃, so R12 refrigerant can hardly evaporate in each evaporator section (18A) (18B) (because the evaporation temperature is -35℃), so R12
The refrigerant hardly contributes to cooling the cascade condensers (28) (30). That is, the R12 refrigerant flows through the refrigerant circuit and returns to the electric compressor (13) with the lubricating oil of the electric compressor (13) dissolved therein. ) (18B>) The low-temperature refrigerant passes through the accumulators (21) and (24) and flows into the oil coolers (23) and (26), respectively.As will be explained later, the low-temperature refrigerant that has passed through the oil coolers (23) and (26) tends to become hot due to being filled with a refrigerant with a low boiling point. Electric compressor of low temperature side refrigerant circuit (11) (12)
22>(25) can be cooled well. In addition, liquid R12 refrigerant flows into the oil cooler (23) from the oil return holes normally formed in the outlet pipes from the accumulators (21) and (24).
(26) and evaporates there, so each electric compressor (
22) The cooling of (25) becomes even better, and this also eliminates the liquid returning to the electric compressor (13) and prevents damage. In addition, each electric compressor (22) (25) is connected to a condenser (2) of each low temperature side refrigerant circuit (11) (12).
7) Evaporator parts (18A) (18B) corresponding to (29)
), for example, when the second low-temperature side refrigerant circuit (12) is not in operation as described later, the solenoid valve (19> is closed and the oil cooler (26) is cooled.
The electric compressor (25) is stopped due to no refrigerant flowing to it.
This also prevents unnecessary cooling.

Next, the discharge side pipe (22D) of the electric compressor (22) that constitutes the first low temperature side refrigerant circuit (11) is connected to the condenser (27), and then to the gas-liquid separator (31). The gas phase piping (32) coming out of the gas-liquid separator (31) passes through the intermediate heat exchanger (33) and is connected to the next gas-liquid separator (34), and then the liquid phase piping (35). is connected between intermediate heat exchangers (33) and (38) via a dryer (36) and a pressure reducer (37).Also, the liquid phase pipe ( 39) is connected between the intermediate heat exchanger (38) and (42) via the dryer (40) and the pressure reducer (41). > passes through the intermediate heat exchanger (38), then the intermediate heat exchanger (42), the dryer (44), the pressure reducer (45), and is connected to the evaporator (46). .

This evaporator (46) is attached to the outside wall of the first storage chamber (4). After passing through the evaporator (46), the refrigerant pipe is connected to the intermediate heat exchanger (42) (3B>(33) one after another in the order of
2) is connected to the suction side piping (225).

Similarly to the first low temperature side refrigerant circuit (11), the second low temperature side refrigerant circuit (12) also has a discharge side pipe (2
5D) and a condenser (29) between the suction side pipe (255),
Gas-liquid separator (50) (53), each gas phase piping (51) (6
2) and liquid phase piping (54) (58), dryer (55) (
59) (63), pressure reducer (56) (60) (64), intermediate heat exchanger (52) (57) (61), evaporator (65)
and an accumulator (66) are connected to each other to form a similar refrigerant closed circuit. The evaporator (65) is attached to the outside wall of the second storage chamber (5).

Four types of mixed refrigerants having different boiling points are sealed in both low-temperature side refrigerant circuits (11) and (12). That is, R12 (35% by weight
), R13B1 (39% by weight), R14 (22% by weight)
and R50 (4% by weight) are sealed in a pre-mixed state.

Next, both low temperature side refrigerant circuits (11) (12) in steady state
) refrigerant circulation will be explained. Electric compressor (22) (
The high-temperature, high-pressure gaseous mixed refrigerant discharged from the first
Or second cascade capacitor (2B>(30)
The R12 and R13B1 refrigerants in the mixed refrigerant flow into the gas-liquid separators (31) and (50) in a condensed state. At this point, R14 and R50 in the mixed refrigerant are still in a gaseous state due to their extremely low boiling points.
is the gas phase pipe (32) (51), R12 and R13B1
is separated into liquid phase piping (35) and (54). The refrigerant mixture that has flowed into the gas phase pipes (32) and (51) exchanges heat with the intermediate heat exchanger (33 bar 52) and is condensed.
The gas-liquid separator (34) (53) is reached. Here, the low-temperature refrigerant returning from the evaporators (46) and (65) flows into the intermediate heat exchangers (33) and (52), respectively, and the R13B1 flows into the liquid phase pipes (35 and 54), respectively. The refrigerant passes through the dryer (36) (55) and then the pressure reducer (37) (56)
After being depressurized by the intermediate heat exchanger (33 bar 52)
The temperature of the intermediate heat exchangers (33) and (52) is about -80° C., since the intermediate heat exchangers (33) and (52) contribute to cooling by flowing into and evaporating there. Therefore, R14 in the mixed refrigerant that has passed through the gas phase pipes (32) and (51) is condensed and liquefied, and R
50 is still in a gaseous state due to its lower boiling point. Therefore, R14 connects the liquid phase pipe (3) from the gas-liquid separator (34) (53).
9) to (58), and R50 is the gas phase piping (43) (6
2), and R14 is a dryer (40) (
59), the pressure is reduced in the pressure reducers (41) and (60), and the mixture flows into the intermediate heat exchanger (42 bar 38) or between (61) and (57), respectively, and then flows into the intermediate heat exchanger (38) and (57). It evaporates. The intermediate heat exchanger (38) (57) has an evaporator (
The temperature of the intermediate heat exchangers (38) and (57) is about -100°C because the return low-temperature refrigerant from 46>(65) flows in and the evaporation of R14 further contributes to cooling. Furthermore, the intermediate heat exchanger (42) (61) is equipped with an evaporator (
46) Since the return low-temperature refrigerant from (65) is immediately flowing in, its temperature is extremely low, about -120"C, so it is ) (61) and gas phase piping (
The refrigerant R50 with the lowest boiling point that passes through 43) < 62) is condensed and liquefied, passes through dryers (44) and (63), and is then sent to a pressure reducer (
45) After being depressurized at (64), the respective evaporators (4
6) flows into (65) and evaporates there. At this time, the temperature of the evaporators (46) and (65) has reached -150°C. This is the final temperature reached by the refrigeration apparatus (RA), and it becomes possible to create an extremely low temperature environment in the first and second storage chambers <4> (5). The refrigerant R50 coming out of the evaporator (46) is transferred to the intermediate heat exchanger (42) (38) (33
), and the refrigerant R50 coming out of the evaporator (65) sequentially flows into and out of the intermediate heat exchangers (61), (57), and (52), respectively, and flows into the accumulator while merging with the refrigerants R14, R13B1, and R12. After separating the unevaporated refrigerant at (47) and (66), the electric compressor (22) and (25)
each inhaled. In addition, in this circulation, R12 refrigerant hardly contributes to cooling, and the electric compressor (22) (2
5) functions to return the lubricating oil.

Next, FIG. 3 shows a control electric circuit for the refrigeration apparatus (RA) of the present invention. (AC) (AC) is an alternating current power supply, (70
) is the power switch, which provides power to all devices in the subsequent stage. (13M) is the high temperature side refrigerant circuit (1
This is a motor for driving the electric compression m(13) of No. 0), and is continuously operated while the power switch (70) is closed. (7
1) is a temperature controller for the first storage chamber (4) that includes a rectifier circuit, etc. Based on a temperature detector (72) that senses the temperature of the evaporator (46), it outputs an output when the temperature reaches -150°C, for example. Generation of the output voltage between the terminals (71A) and (71B) is stopped, the temperature rises to -140°C, and the output voltage is generated. A relay fill (R,) and a high voltage switch (73) can be connected in series between the output terminals (71A) and (71B). The high pressure switch (73) senses the discharge side pressure of the electric compressor (22),
For example, increase to 26 kg/cm2 and open the contact, 8 k
g/cm” and closes the contacts. (74) is the cold start thermostat and the accumulator (21
), and when the temperature drops to, for example, -35°C, the contact closes, and when the temperature rises to -10°C, the contact opens,
It is connected to the power source (AC) in series with the normally open contact (51) of the relay coil (R8) and the relay fill (R1). (22M) is a motor for driving the electric compressor (22) of the first low-temperature side refrigerant circuit (11>), and the relay coil (
R1) is connected in series with the normally open contact (S, ).

(75) is a temperature regulator for the second storage chamber (5), and based on the temperature detector (76) that senses the temperature of the evaporator (65), when the temperature reaches -150°C, the output terminal <75
A) Stop generating the output voltage between (75B) and -140
°C to generate an output voltage. Output terminal (75A
) (75B), a relay coil (R1) and a high voltage switch (77) can be connected in series. The high pressure switch (77) senses the discharge side pressure of the electric compressor (25) and operates in the same way as the high pressure switch (73). (7B) is a low temperature start thermostat that senses the temperature of the accumulator (24), operates in the same way as the low temperature start thermostat (74), and connects the normally open contact (S, ) of the relay coil (R1) and the relay coil ( Can be connected in series with R4) (25M)
is the electric compressor (25) of the second low temperature side refrigerant circuit (12)
This is a driving motor and can be connected in series with the normally open contact (S4) of the relay fill (R4). (19A) is a solenoid valve (
The solenoid valve (19) is the coil (19).
A) is energized to open the flow path, and the relay coil (R
6) is connected in series with the normally open contact (Sax). (80
) is a temperature detector that senses the temperature of the evaporator (46), for example, and closes the contact when the temperature of the evaporator (46) drops to, for example, -150°C, and the relay coil (R,) is normally open. A parallel circuit is formed with the contact (Sl,), and this parallel circuit is connected in series with the relay fill (R6).

Next, the operation of the refrigeration system (RA) will be explained. Freezer (1)
is installed and the power switch (70) is closed, the motor (13M) starts, the electric compressor (13) operates, and refrigerant begins to circulate within the high temperature side refrigerant circuit (10).

At this time, the evaporator (46), accumulator (21) and (
24) is close to room temperature, so the temperature detector (80)
, the cold start thermostats (74) and (78) are open, so the relay coil (R1) is not energized;
The contact (SS + ) is open, the solenoid valve (19) is closed, and the relay coil (R,) (R,) is energized regardless of the temperature controller (71) (75). figure,
Since the contact (S,) is open, the motor (22M)
(25M) does not start. Therefore, in the refrigeration system (RA"), the cooling operation of only the high temperature side refrigerant circuit (10) can continue,
Furthermore, since the solenoid valve (19) is closed, the refrigerant flows only to the first evaporator section (18A) and evaporates. As a result, the temperature of the first evaporator section (18A) decreases, and as a result, liquid refrigerant accumulates in the accumulator (21), and when the temperature decreases to -35°C, the low temperature start thermostat (74 ) closes. At this time, the evaporator (4
Since the temperature of point 6) is high, the temperature regulator (71) also generates an output voltage and the contact (51) is closed. Therefore, when the cold start thermostat (74) closes, the relay coil (
R2) is energized, the switch (S,) is closed, and the motor (
22M) is activated, mixed refrigerant is discharged from the electric compressor (22) and begins to circulate within the circuit (11). At this time, since the refrigerant in the first low-temperature side refrigerant circuit (11) is almost in a gas state, the pressure on the discharge side of the electric compressor (22) rises rapidly and reaches 26 kg/an'', and the high pressure switch ( 73) opens to cut off the current to the relay coil (R1), and the switch (S
l) is opened, the relay coil (R1) is de-energized, the switch (S,) is opened, and the motor (22M) is stopped. This completely prevents the pressure from increasing on the discharge side of the electric compressor (22), thereby preventing damage to the electric compressor (22).

By stopping the electric compressor (22), the discharge side piping (22D
) decreases to 8 kg/CT11", the high pressure switch (73) closes again and the motor (22M) is started in the same manner as described above, but the pressure in the discharge side piping (22D) decreases to 26 kg/CT11".
cm'', the high voltage switch (73) opens again and the motor (22M) stops.
As the refrigerant with a high boiling point evaporates and gradually exerts a cooling effect, the temperature gradually decreases from the intermediate heat exchanger (33) and the motor (22M) starts and stops repeatedly. ) When the pressure rise in the discharge side piping (22D) at startup does not reach 26 kg/cm, the motor (2
2M) It becomes continuous operation. As the electric compressor (22) is continuously operated, the refrigerant with a low boiling point is also condensed and gradually begins to exert a cooling effect, and each intermediate heat exchanger (33) (
38) The temperatures of (42) and the evaporator (46) are gradually lowered to reach the aforementioned final temperature (-150°C).

As a result, the temperature regulator (71) stops generating output voltage, the relay coil (R1) becomes de-energized, and the contacts (S,
) opens, the contact (S) also opens, the motor (22M) stops, and when the temperature of the evaporator (46) rises to 1140°C again, an output voltage is generated and the motor (22M) is started.

This keeps the inside of the first storage chamber (4) cooled to an average of about -145°C.

On the other hand, when the evaporator (46) reaches -150°C, the temperature detector (80) closes the contact, the relay coil (R6) is energized, the contact (SS□>(55,) closes, and the relay coil (R8 ) itself holds itself by closing the contact (56). When the contact (Sa+) closes, the fill (19A)
is energized, the solenoid valve (19) opens, and the refrigerant flows into the second evaporator section (18B), where it begins to evaporate and the temperature decreases, and eventually the temperature of the accumulator (24) also decreases. When the temperature drops to -35°C, the low temperature starting thermostat (78) closes its contacts, energizes the relay coil (R4), closes its contacts (S4), and starts the motor (25M). Below, the temperature of the intermediate heat exchanger (52) (57) (61) and evaporator (65) decreases by the same operation as that of the first low-temperature side refrigerant circuit (11), and similarly, the temperature of the second storage compartment decreases. (5) Cool the inside to an average of -145°C.

In this way, when the freezer (1) is installed, when the cooling operation starts later, the cooling operation is started from both low temperature side refrigerant circuits (11) and (12) one at a time, that is, from the first low temperature side refrigerant circuit (11),
Since they are not started at the same time, the load applied to the electric compressor (13) of the high temperature side refrigerant circuit (10) at the start of the cooling operation is reduced. Moreover, after the first low-temperature side refrigerant circuit (11) reaches its target cooling capacity, that is, it becomes stable, the first low-temperature side refrigerant circuit (11) becomes the high-temperature side refrigerant circuit (10).
Since the second low-temperature side refrigerant circuit (12) is activated after the load on the high-temperature side refrigerant circuit (10) is lightest, the load applied to the high-temperature side refrigerant circuit (10) at the start of the cooling operation becomes the lightest. In addition, since the low temperature side refrigerant circuit is composed of two circuits (11) (12), the electric compressors (13) (22) (25) can also be of small capacity, reducing power consumption at startup. This eliminates the need for large-capacity power supplies, and achieves low vibration and noise.

In the embodiment, the inside of the main body (2) of the freezer (1) is partitioned by a heat insulating partition wall (3) to form a first storage chamber (4) and a second storage chamber (5). Second low temperature side refrigerant circuit (1
1) The configuration is such that the evaporators (46) and (65) of (12) are used for cooling, but the structure is not limited thereto. may be cooled by both evaporators (46) and (65). In that case, after the temperature of the evaporator (46) of the first low-temperature side refrigerant circuit (11) reaches the target temperature, the electromagnetic valve (19)
, the rate of temperature drop in the storage room as a whole slows down.

(G) Effects of the Invention According to the present invention, since the low-temperature side refrigerant circuit is configured with two refrigerant circuits, the load shared by each circuit becomes small, so even when the space to be cooled is large, the low-temperature side refrigerant The electric compressor in the circuit can be of small capacity. In addition, at the start of cooling operation, the on-off valve stops the refrigerant from flowing into the second evaporator section, cools only the first evaporator section, and starts cooling operation from the first low temperature side refrigerant circuit. This reduces the load on the electric compressor of the refrigerant circuit and makes it possible to sufficiently cool each evaporator section at the start of cooling operation, thereby suppressing the pressure rise at the start of the low-temperature side refrigerant circuit. As a result, the durability of the electric compressor can be improved. Furthermore, this allows only one high-temperature side refrigerant circuit to be provided, thereby simplifying the configuration. Furthermore, as a result of the above, it is possible to reduce the capacity of the electric compressor in each refrigerant circuit, thereby realizing a refrigeration system with reduced power consumption, low vibrations, and low noise.

[Brief explanation of the drawing]

Each figure shows an embodiment of the present invention; FIG. 1 is a perspective view of a freezer, FIG. 2 is a refrigerant circuit diagram of the refrigeration system, and FIG. 3 is an electric circuit diagram thereof. (RA)...refrigeration device, (10)...high temperature side refrigerant circuit, (11)...first low temperature side refrigerant circuit, (12)...
)...Second low temperature side refrigerant circuit, (18A) (18B
)...first and second evaporator parts, (19)...
Solenoid valve, (2B)<30>...first and second cascade capacitors, (80)...temperature detector.

Claims (1)

[Claims] 1. A high-temperature side refrigerant circuit having first and second evaporator sections, and first and second low-temperature side refrigerant circuits having both the evaporator sections and condensers respectively constituting heat exchangers. Becomes,
An on-off valve is provided to control the flow of refrigerant to the second evaporator section, and the on-off valve prohibits the flow of refrigerant to the second evaporator section when the cooling operation of the high temperature side refrigerant circuit is started. A refrigeration system comprising a control device that starts cooling operation from a low-temperature side refrigerant circuit.