JPH10339509A - Freezer for freezing container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit the freezing capacity at operation under specified condition to its maximum, in a freezer for a freezing container equipped with a heat exchanger for overcooling. SOLUTION: This device is equipped with a refrigerant circuit where a compressor 1, a condenser 2, a receiver 3, an electronic expansion valve 4 and an evaporator 5 are connected in order, and a heat exchanger 6 for overcooling is laid which gives a refrigerant overcooling by exchanging the heat between the liquid refrigerant led from a receiver 3 and the gas refrigerant led from the evaporator 5. In this case, the aperture control of an electronic expansion valve 4 is performed so that the overheating may be 0 deg.C or under (that is, the gas refrigerant at the outlet of the evaporator 4 is in wet condition) in the operation range where high freezing capacity is required, by laying a control means 16 which controls the aperture of the electronic expansion valve 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus for a refrigerating container with an improved refrigerating capacity.

[0002]

2. Description of the Related Art Generally, a refrigerating apparatus for a refrigerating container includes a refrigerant circuit in which a compressor, a condenser, a receiver, an electronic expansion valve, and an evaporator are sequentially connected to prevent a refrigerant from being sucked into the compressor. In order to maximize the refrigeration capacity, the superheat control (that is, SH control) for controlling the opening degree of the electronic expansion valve so that the outlet refrigerant temperature of the evaporator becomes slightly higher than the inlet refrigerant temperature is performed. It is running.

In the above superheat control, the superheat is 0 ° C.
The refrigeration capacity rises when it is controlled to be close to
When the superheat reaches 0 ° C., the refrigerant at the outlet of the evaporator becomes wet, and the liquid refrigerant is sucked into the compressor. Then, the refrigerating capacity rapidly decreases. When the degree of superheat approaches 0 ° C., as shown in FIG. 5A, the opening degree control of the electronic expansion valve becomes unstable (in other words, it becomes difficult to maintain a constant degree of superheat), and the degree of superheat is reduced. A hunting phenomenon that repeats between 0 ° C. and 2-3 ° C. occurs. When such a hunting phenomenon occurs, as shown by a dotted line A in FIG.
5 ° C. is the optimum value in the superheat control.

[0004]

By the way, in the case of a refrigerating apparatus for a refrigerating container, in order to improve the refrigerating capacity,
There is a type provided with a supercooling heat exchanger for exchanging heat between a liquid refrigerant guided from a receiver and a gas refrigerant guided from an evaporator to give supercooling to the liquid refrigerant. In this heat exchanger for supercooling, while the liquid refrigerant is supercooled (that is, cooled), the gas refrigerant guided from the evaporator is heated.

Therefore, in the case of a refrigerating apparatus for a refrigeration container provided with a subcooling heat exchanger, even if the outlet gas refrigerant of the evaporator is in a wet state, the refrigerant is heated in the subcooling heat exchanger, so that the suction of the compressor The side gas refrigerant does not become wet, and the refrigerating capacity does not decrease even if the degree of superheat is set to 0 ° C. or less. Further, in the refrigeration apparatus for a refrigeration container, since a large refrigeration capacity is required under the conditions of a high outside temperature and a low inside temperature, the superheat degree is set to 0 ° C. or less under the above conditions. As a result, there is a demand for securing the highest refrigeration capacity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is intended to maximize the refrigeration capacity of a refrigeration container refrigeration system equipped with a subcooling heat exchanger during operation under predetermined conditions. It is intended to be.

[0007]

In the basic configuration of the present invention (the invention of claim 1), as means for solving the above-mentioned problems, a compressor 1, a condenser 2, a receiver 3, and an electronic expansion valve 4 are provided.
And a refrigerant circuit in which the liquid refrigerant guided from the receiver 3 and the gas refrigerant guided from the evaporator 5 exchange heat to provide supercooling to the liquid refrigerant. In the refrigerating container refrigerating apparatus provided with the heat exchanger 6, the opening degree of the electronic expansion valve 4 is controlled so that the superheat degree SH in the evaporator 3 becomes 0 ° C. or less in an operation region where a high refrigerating capacity is required. Control means 16
Is attached.

[0008] With the above configuration, in the operation region where high refrigeration capacity is required, the degree of superheat SH is 0 ° C.
The opening degree of the electronic expansion valve 4 is controlled so that the gas refrigerant at the outlet of the evaporator 5 is in the following state (that is, the gas refrigerant at the outlet of the evaporator 5 is wet). In the heat exchanger 6, the refrigerant is heated by heat exchange with the liquid refrigerant guided from the receiver 3, so that the suction gas refrigerant of the compressor 1 does not become wet. Therefore, the evaporator 5
The maximum refrigeration capacity can be ensured.

When the control by the control means 16 is stopped when the suction gas refrigerant of the compressor 1 becomes wet, the opening degree of the electronic expansion valve 4 is reduced. Is too large and the amount of heat in the supercooling heat exchanger 6 cannot be removed from the wet state of the gas refrigerant at the outlet of the evaporator 5, the control to reduce the superheat to 0 ° C. or less is stopped, and the normal superheat The control is shifted to the control, so that the suction of the liquid refrigerant by the compressor 1 can be prevented.

As described in the third aspect of the present invention, a suction temperature detecting means 13 for detecting a suction gas refrigerant temperature T ₁ of the compressor 1 is additionally provided, and the control means 16 is detected by the suction temperature detecting means 13. It has been sucked gas refrigerant temperature T ₁ is the evaporator 5 suction gas refrigerant temperatures T ₁ detected by the suction temperature detecting means 13 at the time of transition from the state dry the refrigerant state in the wet state at the outlet side of the '
In the case where the opening degree of the electronic expansion valve 4 is controlled so as to lower the temperature by a predetermined value, the control to reduce the superheat degree to 0 ° C. or less changes the refrigerant state at the outlet side of the evaporator 5 from a dry state to a wet state. At the time of transition, it is performed by comparing the suction gas refrigerant temperature T ₁ ′ detected by the suction temperature detection means 13 with the suction gas refrigerant temperature T at that time, so that it is affected by disturbance such as outside air temperature. And the reliability is improved.

According to a fourth aspect of the present invention, the wet state of the suction gas refrigerant of the compressor 1 is detected based on a decrease in the suction gas refrigerant temperature T ₁ detected by the suction temperature detecting means 13. , by monitoring the suction gas refrigerant temperature T _1, will be able to reliably prevent the liquid refrigerant inhaled into the compressor 1, it is possible to ensure the reliability of the device.

As in the present invention, the discharge temperature detecting means 17 for detecting the discharge gas refrigerant temperature Th of the compressor 1 and the discharge pressure detecting means 15 for detecting the discharge gas refrigerant pressure Ph of the compressor 1 are provided. And the wet state of the suction gas refrigerant of the compressor 1 is increased by the rise of the discharge gas refrigerant temperature Th detected by the discharge temperature detection means 17 and the discharge gas refrigerant pressure detected by the discharge pressure detection means 15. When the detection is performed based on the rise of Ph, the discharge gas refrigerant temperature Th and the discharge gas refrigerant pressure Ph
, The suction of the liquid refrigerant to the compressor 1 can be reliably prevented, and the reliability of the device can be ensured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First Embodiment (Corresponding to Claims 1 to 4) FIG. 1 shows a refrigerant circuit diagram of a refrigeration container refrigeration apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, the refrigerating apparatus for a refrigerating container includes a refrigerant circuit in which a compressor 1, a condenser 2, a receiver 3, an electronic expansion valve 4, and an evaporator 5 are sequentially connected. 3 and the evaporator 5
A supercooling heat exchanger 6 for exchanging heat with the gas refrigerant guided from the heat exchanger to provide supercooling to the liquid refrigerant is provided. Reference numeral 7 denotes a condenser fan for cooling the condenser 2, and reference numeral 8 denotes an evaporator fan for supplying the inside air to the evaporator 3.

The refrigerant circuit is provided with a liquid injection circuit 9 for injecting a part of the liquid refrigerant guided from the receiver 3 into the suction side of the compressor 1. Reference numeral 10 denotes an on-off valve that is opened at the time of liquid injection.

The refrigeration apparatus for a refrigeration container includes:
A temperature sensor 11 acting as inlet refrigerant temperature detecting means for detecting the inlet refrigerant temperature Ti of the evaporator 5, a temperature sensor 12 acting as outlet refrigerant temperature detecting means for detecting the outlet refrigerant temperature To of the evaporator 5, The compressor 1
A temperature sensor 13 acting as a suction temperature detecting means for detecting the temperature T ₁ of the suction gas refrigerant, a temperature sensor 14 acting as a temperature detecting means for detecting the air temperature Tr in the refrigerator, and a discharge gas refrigerant of the compressor 1. A pressure sensor 15 acting as a discharge pressure detecting means for detecting the pressure Ph is additionally provided.

The temperature information detected by the temperature sensors 11 to 14 (that is, the inlet refrigerant temperature Ti, the outlet refrigerant temperature To, the suction gas refrigerant temperature T ₁ , and the in-compartment air temperature T
r) and the pressure information detected by the pressure sensor 15 (that is, the discharge gas refrigerant pressure Ph) are input to the controller 16 acting as control means.
6 performs various arithmetic processing based on the temperature information and the pressure information, and outputs the result to the electronic expansion valve 4 as a control signal. That is, the controller 16 has a function of controlling the opening of the electronic expansion valve 4 so that the degree of superheat SH in the evaporator 3 becomes 0 ° C. or less in an operation region where a high refrigeration capacity is required. is there.

Next, the superheat degree control in the refrigeration apparatus for a refrigeration container according to the present embodiment will be described in detail with reference to a flowchart shown in FIG.

[0020] The temperature sensor 11 in step S ₁
Temperature information (ie, inlet refrigerant temperature Ti, outlet refrigerant temperature To, suction gas refrigerant temperature T ₁ , internal air temperature Tr) and pressure information (ie, discharge gas refrigerant pressure Ph) from pressure sensor 14 and pressure sensor 15 are input. , superheat degree control (hereinafter, referred to SH control) in step S ₂ is executed. The SH control is a normal SH control, and the degree of superheat SH (that is, the difference between the outlet refrigerant temperature To of the evaporator 5 and the inlet refrigerant temperature Ti).
= 3-5 ° C., the opening of the electronic expansion valve 4 is controlled. The internal air temperature Tr in step S ₃ is set value T
rs (for example, −16 ° C.) or lower and the discharge gas refrigerant pressure Ph is determined to be equal to or higher than the set value Phs (for example, 950 kpa).

In general, in the refrigerating apparatus for a refrigerating container, as shown in FIG. 3, SH control is executed when shifting from the pull-down operation region to the refrigerating region, but the air temperature Tr in the refrigerator becomes -16.degree. In a region where the outside air temperature is 38 ° C. or higher (here, the discharge gas refrigerant pressure Ph is 950 kpa or higher), a high refrigeration capacity is required.
H (0 ° C.) control (that is, control for setting SH to 0 ° C. or less) is executed. Therefore, refrigeration container refrigeration system with each other to be determined whether the transition to the high refrigeration capacity region in step S _3.

[0022] If an affirmative decision is made in step S _3,
The process proceeds to step S _4, starts SH (0 ° C.) control to reset the target degree of superheat SH ₀ in step S _5. The target superheat degree SH ₀ set at this time is about 3 ° C. (see FIG. 4) which is the superheat degree at the time when the outlet side gas refrigerant of the evaporator 5 shifts from the dry state to the wet state. The reason for this is that if the target degree of superheat SH ₀ is 0 ° C., it is not possible to detect too much wetness, an overshoot occurs in control, and the electronic expansion valve 4 becomes too open.

[0023] Thereafter, the opening degree of the electronic expansion valve 4 is PI control in step S _6. The PI control is between difference 0 ℃ and target superheat degree SH ₀ of the outlet refrigerant temperature To and the inlet refrigerant temperature Ti of the evaporator 5 in step S ₇ (i.e.,
0 <To-Ti <continues until SH _0), and if an affirmative decision is made in step S _7, the process proceeds to step S _8,
At this time, the intake gas refrigerant temperature T ₁ ′ is sampled, and at the same time, the opening degree of the electronic expansion valve 4 is controlled by PI.

[0024] The PI control is lower than the difference is 0 ℃ the outlet refrigerant temperature To and the inlet refrigerant temperature Ti of the evaporator 5 in step S ₉ (i.e., To-Ti <0) is continued until the step S ₉ If an affirmative determination is made in, the process proceeds to step S _10, control the intake temperature control (hereinafter, referred to as T ₁ control) is changed to a target set value of the T ₁ control T ₁ s =
T ₁ -2 ° C. (see FIG. 4).

In the T ₁ control, a comparison is made between the intake gas refrigerant temperature T ₁ and the target set value T ₁ s in step S ₁₁ , and if it is determined that T ₁ <T ₁ s, As shown in FIG. 4, since the superheat degree SH ≦ 0 ° C.,
Fixing the opening degree of the electronic expansion valve 4 in step S _12.
On the other hand, if it is determined that T ₁ ≧ T ₁ s in step S _11, as shown in FIG. 4, since the degree of superheat SH is a hunting area repeating 0 ℃ and 3 ° C., the step S ₁₃
The opening of the electronic expansion valve 4 opens in one pulse / min in, and returns to step S _11, suction gas refrigerant temperature T ₁ of
Monitoring.

When the opening degree of the electronic expansion valve 4 is controlled by the T ₁ control, the electronic expansion valve 4 becomes too open, and the amount of heating in the subcooling heat exchanger 6 causes may not be escaped the wet state of the exit gas refrigerant, since the suction gas refrigerant of the compressor 1 may become wet state, suction gas refrigerant temperatures T ₁ in step S ₁₄
Is compared with the lower limit target set value T ₁ s ′ (for example, T ₁ −10 ° C.). If it is determined that T ₁ <T ₁ s ′, the process proceeds to step S ₁₅ , where T ₁ control is performed. a stop, and then return to step S _1.

As described above, in the present embodiment, in an operating region where a high refrigeration capacity is required, the superheat degree is 0 ° C. or less (that is, the outlet gas refrigerant of the evaporator 5 is in a wet state). The opening degree control of the electronic expansion valve 4 is performed so that the gas refrigerant in the wet state that has exited the evaporator 5 is heated by the supercooling heat exchanger 6 with the liquid refrigerant guided from the receiver 3. The refrigerant is heated by the replacement, so that the suction gas refrigerant of the compressor 1 does not become wet. Therefore, the capacity of the evaporator 5 can be maximized,
The highest refrigeration capacity can be ensured (see the solid line B in FIG. 5B).

Also, the opening of the electronic expansion valve 4 becomes too large, and the amount of heating in the subcooling heat exchanger 6 is limited by the evaporator 5.
When the wet state of the outlet gas refrigerant cannot be completely removed, the control for reducing the superheat degree to 0 ° C. or lower is stopped, and the process shifts to the normal superheat degree control, and the suction of the liquid refrigerant to the compressor 1 can be prevented. it can.

Further, the control for reducing the superheat degree to 0 ° C. or less
The comparison is made between the suction gas refrigerant temperature T ₁ ′ at the time when the refrigerant state at the outlet side of the evaporator 5 shifts from the dry state to the wet state and the suction gas refrigerant temperature T at that point, and disturbances such as the outside air temperature And the reliability is improved.

Second Embodiment (Corresponding to Claims 1, 2 and 5) FIG. 6 shows a refrigerant circuit diagram of a refrigeration container refrigeration apparatus according to a second embodiment of the present invention. .

In this case, instead of the temperature sensor 13 in the first embodiment, the discharge gas refrigerant temperature T
A temperature sensor 17 acting as a discharge temperature detecting means for detecting h is provided. Therefore, the controller 16 acting as the control means includes the temperature sensors 11, 12, 1
4 and 17 (that is, the inlet refrigerant temperature Ti, the outlet refrigerant temperature To, the inside air temperature Tr, and the discharge gas refrigerant temperature Th) and the pressure information from the pressure sensor 15 (that is,
Various arithmetic processes are performed based on the discharge gas refrigerant pressure Ph), and the results are output to the electronic expansion valve 4 as control signals. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

Next, the superheat degree control in the refrigeration container refrigeration apparatus according to the present embodiment will be described in detail with reference to the flowchart shown in FIG.

[0033] The temperature sensor 11 in step S _1,
Temperature information (ie, inlet refrigerant temperature Ti, outlet refrigerant temperature To, discharge gas refrigerant temperature Th, internal air temperature Tr) and pressure information (ie, discharge gas refrigerant pressure Ph) from 12, 14, 17 and pressure sensor 15. There are input, superheat degree control (hereinafter, referred to SH control) in step S ₂ is executed. The SH control is a normal SH control and the superheat S
The opening degree of the electronic expansion valve 4 is controlled so that H (that is, the difference between the outlet refrigerant temperature To of the evaporator 5 and the inlet refrigerant temperature Ti) = 3 to 5 ° C. The internal air temperature Tr in step S ₃
Is less than or equal to a set value Trs (for example, −16 ° C.) and the discharge gas refrigerant pressure Ph is equal to or less than a set value Phs (for example, 950 kp).
a) It is continued until it is judged that it is above. This control determines the operation range, and is based on the same reason as in the first embodiment.

[0034] If an affirmative decision is made in step S _3,
The process proceeds to step S _4, starts SH (0 ° C.) control to reset the target degree of superheat SH ₀ in step S _5. The target degree of superheat SH ₀ set at this time is set to a degree of superheat SH = about 3 ° C. (see FIG. 4) at the time when the outlet side gas refrigerant of the evaporator 5 shifts from a dry state to a wet state. The reason for this is that if the target degree of superheat SH ₀ is 0 ° C., it is not possible to detect too much wetness, an overshoot will occur in control, and the electronic expansion valve 4 will be too open.

[0035] Thereafter, the opening degree of the electronic expansion valve 4 is PI control in step S _6. The PI control is between difference 0 ℃ and target superheat degree SH ₀ of the outlet refrigerant temperature To and the inlet refrigerant temperature Ti of the evaporator 5 in step S ₇ (i.e.,
0 <To-Ti <continues until SH _0), and if an affirmative decision is made in step S _7, the process proceeds to step S _8,
At this time, the discharge gas refrigerant pressure Ph ′ and the discharge gas refrigerant temperature Th ′ are sampled, and at the same time, the opening degree of the electronic expansion valve 4 is controlled by PI.

[0036] The PI control is continued until less than difference 0 ℃ the outlet refrigerant temperature To and the inlet refrigerant temperature Ti of the evaporator 5 in step S ₉ (i.e., To-Ti <0), the step S If an affirmative determination is made in _9, the process proceeds to step S _10, the opening degree of the electronic expansion valve 4 is fixed.

When the opening degree of the electronic expansion valve 4 is controlled by the above control, the electronic expansion valve 4 becomes too open, and the amount of heat in the supercooling heat exchanger 6 is reduced by the evaporator 5.
May not be able to get out of the wet state of the outlet gas refrigerant,
Since the suction gas refrigerant of the compressor 1 may become wet state, the difference between the discharge gas refrigerant pressure Ph and the sampling value Ph 'and in step S ₁₁ and step S ₁₂ set value Phs (e.g., 2 kg · f) and And the difference between the discharge gas refrigerant temperature Th and the sampling value Th ′ and the set value T
Comparison with hs is made, if it is both affirmative determination, the process proceeds to step S _13, stops SH (0 ° C.) control,
And then return to step S _1.

Other functions and effects are the same as those in the first embodiment, and the description is omitted.

[0039]

According to the invention of the present application (the invention of claim 1),
A refrigerant circuit in which a compressor 1, a condenser 2, a receiver 3, an electronic expansion valve 4, and an evaporator 5 are sequentially connected, and a liquid refrigerant guided from the receiver 3 and a gas refrigerant guided from the evaporator 5; In a refrigeration container refrigeration system provided with a supercooling heat exchanger 6 for exchanging heat and supercooling the liquid refrigerant, the degree of superheating in the evaporator 3 is 0 ° C. or less in an operating state requiring a high refrigeration capacity. A control means 16 for controlling the opening of the electronic expansion valve 4 is provided so that the superheat degree is 0 ° C. or less (ie, the outlet gas of the evaporator 5) in an operation region where a high refrigerating capacity is required. Since the opening degree of the electronic expansion valve 4 is controlled so that the refrigerant is in a wet state, even if the outlet side refrigerant of the evaporator 5 is in a wet state, the refrigerant is guided from the receiver 3 in the supercooling heat exchanger 6. Heat exchange with the liquid refrigerant Becomes to be heated, the suction gas refrigerant of the compressor 1 will not become a wet state. Therefore, the capacity of the evaporator 5 can be maximized, and there is an excellent effect that the maximum refrigeration capacity can be secured.

If the control by the control means 16 is stopped when the suction gas refrigerant of the compressor 1 becomes wet, the opening degree of the electronic expansion valve 4 is reduced. Is too large and the amount of heat in the supercooling heat exchanger 6 cannot be removed from the wet state of the gas refrigerant at the outlet of the evaporator 5, the control to reduce the superheat to 0 ° C. or less is stopped, and the normal superheat The control is shifted to the control, and the suction of the liquid refrigerant to the compressor 1 can be prevented.

As in the third aspect of the present invention, suction temperature detecting means 13 for detecting the suction gas refrigerant temperature T ₁ of the compressor 1 is additionally provided, and the control means 16 is detected by the suction temperature detecting means 13. It has been sucked gas refrigerant temperature T ₁ is the evaporator 5 suction gas refrigerant temperatures T ₁ detected by the suction temperature detecting means 13 at the time of transition from the state dry the refrigerant state in the wet state at the outlet side of the '
In the case where the opening degree of the electronic expansion valve 4 is controlled so as to lower the temperature by a predetermined value, the control to reduce the superheat degree to 0 ° C. or less changes the refrigerant state at the outlet side of the evaporator 5 from a dry state to a wet state. At the time of the transition, the suction gas refrigerant temperature T ₁ ′ detected by the suction temperature detecting means 13 is compared with the suction gas refrigerant temperature T at that time, so that it is less affected by disturbance such as the outside air temperature. , Reliability is improved.

According to a fourth aspect of the present invention, the wet state of the suction gas refrigerant of the compressor 1 is detected by a decrease in the suction gas refrigerant temperature T ₁ detected by the suction temperature detecting means 13. , by monitoring the suction gas refrigerant temperature T _1, will be able to reliably prevent the liquid refrigerant inhaled into the compressor 1, it is possible to ensure the reliability of the device.

As in the present invention, the discharge temperature detecting means 17 for detecting the discharge gas refrigerant temperature Th of the compressor 1 and the discharge pressure detecting means 15 for detecting the discharge gas refrigerant pressure Ph of the compressor 1 are provided. And the wet state of the suction gas refrigerant of the compressor 1 is increased by the rise of the discharge gas refrigerant temperature Th detected by the discharge temperature detection means 17 and the discharge gas refrigerant pressure detected by the discharge pressure detection means 15. When the detection is performed based on the rise of Ph, the discharge gas refrigerant temperature Th and the discharge gas refrigerant pressure Ph
, The suction of the liquid refrigerant to the compressor 1 can be reliably prevented, and the reliability of the device can be ensured.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration container refrigeration apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating superheat control in the refrigeration container refrigeration apparatus according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing transition of an operating state of a general refrigeration apparatus for a refrigeration container.

FIG. 4 is a characteristic diagram showing the relationship between the degree of opening of the electronic expansion valve, the degree of superheat, and the temperature of the suction gas refrigerant during superheat control in the refrigeration apparatus for a refrigeration container according to the first embodiment of the present invention.

FIG. 5A is a characteristic diagram showing a relationship between an electronic expansion valve opening and a degree of superheat, and FIG. 5B is a characteristic diagram showing a relationship between a refrigerating capacity and a degree of superheat.

FIG. 6 is a refrigerant circuit diagram of a refrigeration container refrigeration apparatus according to a second embodiment of the present invention.

FIG. 7 is a flowchart illustrating superheat control in a refrigeration container refrigeration apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

1 is a compressor, 2 is a condenser, 3 is a receiver, 4 is an electronic expansion valve, 5 is an evaporator, 6 is a supercooling heat exchanger, 11 is an inlet refrigerant temperature detecting means (temperature sensor), and 12 is an outlet refrigerant. Temperature detecting means (temperature sensor), 13 is suction temperature detecting means (temperature sensor), 14 is internal chamber temperature detecting means (temperature sensor), 15 is discharge pressure detecting means (pressure sensor), 1
6 the control means (controller), 17 denotes a discharge temperature detection means (temperature sensor), SH is the degree of superheat, T _1, T ₁ 'is suction gas refrigerant temperature, Th is discharged gas refrigerant temperature, Ph is discharged gas refrigerant pressure.

Claims (5)

[Claims] 1. A refrigerant circuit comprising a compressor (1), a condenser (2), a receiver (3), an electronic expansion valve (4), and an evaporator (5) sequentially connected, and the receiver (3). The liquid refrigerant introduced from the evaporator (5) exchanges heat with the gas refrigerant introduced from the evaporator (5), and provides a supercooling heat exchanger (6) for supercooling the liquid refrigerant. Control means (16) for controlling the degree of opening of the electronic expansion valve (4) so that the degree of superheat (SH) in the evaporator (5) is 0 ° C. or less in an operation region where high refrigeration capacity is required. A refrigeration device for a refrigeration container, characterized by having a refrigeration container. 2. The refrigeration system according to claim 1, wherein the control by said control means (16) is stopped when the suction gas refrigerant of said compressor (1) becomes wet. Refrigeration equipment for containers. 3. A suction temperature detecting means (13) for detecting a suction gas refrigerant temperature (T ₁ ) of said compressor (1), and said control means (16) is provided with said suction temperature detecting means (13). ) Detected by the suction gas refrigerant temperature (T
₁ ) is a predetermined temperature from the suction gas refrigerant temperature (T ₁ ′) detected by the suction temperature detecting means (13) at the time when the refrigerant state at the outlet side of the evaporator (5) shifts from a dry state to a wet state. The refrigeration apparatus for a refrigeration container according to any one of claims 1 and 2, wherein the opening degree of the electronic expansion valve (4) is controlled so as to be lowered. 4. The method according to claim 1, wherein the wet state of the suction gas refrigerant of the compressor (1) is detected by a decrease in the suction gas refrigerant temperature (T ₁ ) detected by the suction temperature detection means (13). The refrigeration apparatus for a refrigeration container according to claim 3, characterized in that: 5. A discharge temperature detecting means (17) for detecting a discharge gas refrigerant temperature (Th) of the compressor (1) and a discharge pressure detection for detecting a discharge gas refrigerant pressure (Ph) of the compressor (1). Means (15), and detects the wetness state of the suction gas refrigerant of the compressor (1) by the discharge gas refrigerant temperature (T) detected by the discharge temperature detection means (17).
3. The refrigeration apparatus for a refrigeration container according to claim 2, wherein the detection is performed based on an increase in h) and an increase in a discharge gas refrigerant pressure (Ph) detected by the discharge pressure detection means (15).