JP4699181B2 - Refrigeration circuit used for container refrigeration unit, container refrigeration unit equipped with the same, and operation method of container refrigeration unit - Google Patents

Description

  The present invention relates to a refrigeration circuit used for an air conditioner, a container refrigeration unit (a marine container refrigeration unit or an onshore container refrigeration unit), and more particularly to a refrigeration circuit used for a container refrigeration unit.

As a refrigeration circuit used for a container refrigeration unit, when frost is formed on an evaporator, a hot gas bypass that flows hot gas refrigerant discharged from a compressor to the evaporator (evaporator) inlet side in order to defrost it The thing provided with the means is known (for example, refer patent document 1).
Japanese Patent No. 3343916

  However, in the thing of the said patent document, hot gas refrigerant | coolant of high temperature (for example, about 100 degreeC) will pass an evaporator via a hot gas bypass means. For this reason, when the frost on the evaporator melts, water vapor is generated, which causes water droplets to adhere to the ceiling surface inside the container (inside the container), and the water drops fall on the cargo in the warehouse and damage the luggage. There was a problem such as.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a refrigeration circuit used in a container refrigeration unit capable of preventing the generation of water vapor due to melting of frost attached to an evaporator at the time of defrosting. Yes.

The present invention employs the following means in order to solve the above problems.
The refrigeration circuit used in the container refrigeration unit according to the present invention compresses a low-temperature / low-pressure gas refrigerant into a high-temperature / high-pressure gas refrigerant, and condenses and liquefies the high-temperature / high-pressure gas refrigerant to radiate heat to the outside air. A condenser that functions as a radiator, an expansion valve that decompresses and expands the refrigerant that passes through to form a low-temperature and low-pressure refrigerant, and an evaporator that functions as an evaporator that evaporates and vaporizes the low-temperature and low-pressure liquid refrigerant to remove heat from the inside air. A refrigeration circuit used in a container refrigeration unit having a hot gas defrost pipe connecting a discharge side of the compressor and an evaporator inlet side, and returns the liquid refrigerant that has passed through the condenser into the compressor. A liquid injection solenoid valve is provided in the middle of the refrigerant pipe, and the refrigerant pipe connecting the discharge side of the compressor and the inlet side of the condenser. And discharge temperature sensor is provided in, during the defrosting, if the discharge temperature detected by the discharge temperature sensor exceeds 100 ° C., the liquid injection solenoid valve is configured to be operated in the opening direction .
According to the refrigeration circuit used in such a container refrigeration unit, when the discharge temperature detected by the discharge temperature sensor exceeds 100 ° C. during defrosting, the liquid injection solenoid valve is operated in the opening direction. The liquid refrigerant is injected into the compressor, and the temperature of the gas refrigerant discharged from the compressor is lowered.
As a result, the temperature of the refrigerant flowing into the evaporator through the hot gas defrost pipe at the time of defrosting can be lowered, and generation of water vapor due to melting of frost attached to the evaporator can be prevented.

The container refrigeration unit according to the present invention includes a refrigeration circuit used in the container refrigeration unit .
According to such a container refrigeration unit , generation of water vapor due to melting of frost attached to the evaporator is prevented, so that water droplets adhere to the ceiling surface of the interior (inside the container). It is possible to prevent the luggage from being dropped on the luggage in the warehouse (in the container) and soiling the luggage.

An operation method of a container refrigeration unit according to the present invention includes a compressor that compresses a low-temperature / low-pressure gas refrigerant to form a high-temperature / high-pressure gas refrigerant, and a radiator that condenses and liquefies the high-temperature / high-pressure gas refrigerant to the outside air. A condenser that functions as: an expansion valve that depressurizes and expands the refrigerant that passes through to form a low-temperature and low-pressure refrigerant; an evaporator that functions as an evaporator that evaporates and vaporizes the low-temperature and low-pressure liquid refrigerant to remove heat from the inside air; and A hot gas defrost pipe connecting the discharge side of the compressor and the evaporator inlet side, a liquid injection solenoid valve provided in the middle of a refrigerant pipe for returning the liquid refrigerant that has passed through the condenser into the compressor, and the compressor a discharge side and the method of operating the inlet side and the container refrigeration unit that includes a discharge temperature sensor provided in the middle of the refrigerant pipe connecting the condenser, During frost, the discharge temperature detected by the discharge temperature sensor if it exceeds 100 ° C., so that operating the liquid injection solenoid valve in the opening direction.
According to the operation method of such a container refrigeration unit , at the time of defrosting, when the discharge temperature detected by the discharge temperature sensor exceeds 100 ° C. , the liquid injection solenoid valve is operated in the opening direction, Liquid refrigerant is injected into the compressor, and the temperature of the gas refrigerant discharged from the compressor is lowered.
As a result, the temperature of the refrigerant flowing into the evaporator through the hot gas defrost pipe at the time of defrosting can be lowered, and generation of water vapor due to melting of frost attached to the evaporator can be prevented.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that generation | occurrence | production of the water vapor | steam by melting the frost which arrived at the evaporator can be prevented.

Hereinafter, an embodiment of a refrigeration circuit used in a container refrigeration unit according to the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a configuration diagram of a refrigeration circuit 30 used in the container refrigeration unit according to the present embodiment, and FIG. 2 is a marine container refrigeration unit (refrigeration unit) provided with the refrigeration circuit 30 used in the container refrigeration unit according to the present embodiment. FIG. 3 is a schematic rear view of FIG.

  The marine container refrigeration unit 1 is assembled to one end wall of a rectangular parallelepiped container (not shown), and when the marine container refrigeration unit 1 is operated, the internal temperature of the container becomes −30. The temperature can be maintained at an arbitrarily set temperature in the range of [° C.] to +25 [° C.]. In addition, the container in which the sea container refrigeration unit 1 is assembled can be loaded and transported on a ship, a truck, a railway vehicle or the like.

The gas refrigerant discharged from the compressor 2 enters the water-cooled condenser 3 and / or the air-cooled condenser 4 and is condensed and liquefied. The liquid refrigerant obtained by condensing and liquefying enters the electronic expansion valve 7 through the dryer 5 and the strainer 6, and is adiabatic expansion by being throttled here to become a gas-liquid two-phase refrigerant.
Then, this refrigerant enters the evaporator 8, where it evaporates by cooling the internal air. The evaporated and evaporated refrigerant (that is, gas refrigerant) returns to the compressor 2 through the accumulator 9.

  When the air-cooled condenser 4 is used, the condenser fan 10 is driven by a motor (not shown). Then, after the temperature is raised by exchanging heat with the gas refrigerant in the process of flowing through the air-cooled condenser 4, it is energized by the condenser fan 10 and released into the atmosphere.

  When the water-cooled condenser 3 is used, a water supply pipe (not shown) is connected to an inlet side connection fitting (not shown), and a drain pipe (not shown) is connected to an outlet side connection fitting (not shown). Then, the water control valve (not shown) is opened, and the condenser fan 10 is stopped. Then, the cooling water supplied from the water supply pipe enters the water-cooled condenser 3 through the water pipe (not shown) from the inlet-side connection fitting, where the temperature is raised by exchanging heat with the gas refrigerant, It passes through the water control valve and is discharged from the outlet side fitting through the drain pipe.

The drain condensed on the evaporator 8 is dropped on the drain pan 11 (indicated by a solid line arrow in FIG. 3), and the round hole 12 provided on the bottom surface of the drain pan 11 and the drain hose 13 connected (connected) to the round hole 12 are provided. Then, it is discharged from the drain outlet 13a to the outside.
In FIG. 2, reference numeral 14 denotes a liquid injection solenoid valve for injecting and cooling liquid refrigerant into the compressor 2, and reference numeral 15 denotes a temperature of the discharge side refrigerant pipe (discharge pipe) 55 of the compressor 2. The reference numeral 16 denotes an ejection temperature sensor, 16 is an evaporator fan, and 17 is a control box. In addition, an inspection lid for inspecting equipment in the evaporator section is attached to the front side of the evaporator fan 16, but is omitted here.

As shown in FIG. 1, the refrigeration circuit 30 used in the container refrigeration unit according to this embodiment includes a compressor 2, an air-cooled condenser 4 (and / or a water-cooled condenser 3), an electronic expansion valve 7, and an evaporator 8. And the main elements.
The compressor 2 compresses a low-temperature / low-pressure gaseous refrigerant into a high-temperature / high-pressure gas refrigerant.
The air-cooled condenser 4 (and / or the water-cooled condenser 3) functions as a radiator that condenses and liquefies a high-temperature and high-pressure gas refrigerant and radiates heat to the outside air (cooling water in the case of the water-cooled condenser 3).
The electronic expansion valve 7 depressurizes and expands the refrigerant that passes through it to form a low-temperature and low-pressure refrigerant. The electronic expansion valve 7 is provided with, for example, a stepping motor (not shown) as a drive source, and the stepping motor is driven based on a signal sent from a controller (not shown). The expansion valve 7 is appropriately adjusted to a desired opening degree.
The evaporator 8 functions as an evaporator that evaporates and vaporizes a low-temperature and low-pressure liquid refrigerant to remove heat from the inside air.

  In FIG. 1, reference numeral 31 is provided on the discharge-side refrigerant pipe 55 of the compressor 2, a discharge pressure adjusting valve that holds the discharge pressure at a set pressure or higher, reference numeral 32 is a receiver, reference numeral 33 is an economizer heat exchanger, Reference numeral 34 is an economizer expansion valve, reference numeral 35 is an economizer solenoid valve, reference numeral 36 is a temperature sensing cylinder of the economizer expansion valve 34, reference numeral 37 is a sight glass, reference numeral 38 is a distributor, reference numeral 39 is a suction side refrigerant pipe 56 of the compressor 2. A suction modulation valve that is provided and holds the outlet side pressure (suction pressure) below a set value, numeral 40 is a check valve, numeral 41 is a refrigerant pipe 55 and a suction modulation valve 39 on the downstream side of the discharge pressure regulating valve 31. Gas bypass solenoid valve provided in a return pipe 57 connected between the refrigerant pipe 56 on the downstream side. A solenoid valve for capacity controller (hereinafter referred to as “capacitor solenoid valve”) provided in a bypass pipe 58 for bypassing the gas refrigerant in the middle of compression to the suction side refrigerant pipe 56 of the compressor 2, reference numeral 43 denotes the compressor 2. A hot gas solenoid valve provided in a defrost pipe 59 for introducing a high-temperature / high-pressure discharge gas refrigerant from the pipe 8 into the evaporator 8 through a drain pan hot gas defrost pipe 54, reference numerals 44 and 45 are capillary tubes (fixed resistance), and reference numeral 46 is High pressure switch, reference numeral 47 is a service joint (high pressure), reference numeral 48 is a service valve, reference numeral 49 is a service joint (high pressure), reference numeral 50 is a fusible stopper, reference numeral 51 is a service valve, reference numeral 52 is a service joint (low pressure), 53 is a service joint (intermediate pressure), 54 is a drain pan hot gas deflo It is a door tube.

On the other hand, as described above, the discharge temperature sensor 15 for detecting the temperature of the discharge side refrigerant pipe 55 is provided on the most upstream side of the discharge side refrigerant pipe 55.
Further, in the middle of the refrigerant pipe 56 connecting the accumulator 9 and the compressor 2 (that is, the refrigerant pipe 56 positioned between the suction modulation valve 39 and the service joint (low pressure) 52 in FIG. 1), the compressor 2 A low pressure sensor 18 is provided for detecting the pressure of the refrigerant sucked into the tank.
Further, a high-pressure pressure for detecting the pressure of the refrigerant discharged from the compressor 2 is provided in the discharge-side refrigerant pipe 55 located downstream of the discharge temperature sensor 15 and upstream of the high-pressure switch 46. A sensor 19 is provided.

The discharge temperature sensor 15, the low pressure sensor 18, and the high pressure sensor 19 are electrically connected to the controller 20, and the discharge temperature sensor 15, the low pressure sensor 18, and the high pressure sensor. The data (measured value) detected by 19 is output to the controller 20.
The liquid injection solenoid valve 14 and the suction modulating valve 39 described above are also electrically connected to the controller 20, and are sent from the discharge temperature sensor 15, the low pressure sensor 18, and the high pressure sensor 19 to the controller 20. The liquid injection solenoid valve 14 and / or the suction modulating valve 39 are automatically adjusted to an appropriate valve opening according to the data that has been obtained.
The hot gas solenoid valve 43 is also electrically connected to the controller 20, and the controller 20 detects that frost has formed on the evaporator 8 by well-known frost detection means not shown. Then, the hot gas solenoid valve 43 is opened and the hot gas refrigerant discharged from the compressor is introduced into the evaporator 8 through the drain pan hot gas defrost pipe 54 to start defrost operation for melting frost, and liquid injection is performed as follows. The electromagnetic valve 14 and the suction modulating valve 39 are controlled.

For example, the discharge temperature detected by the discharge temperature sensor 15 at the time of defrosting (when high-temperature and high-pressure gas refrigerant discharged from the compressor 2 flows toward the evaporator 8 via the drain pan hot gas defrost pipe 54) When a predetermined value (for example, 100 ° C., preferably 70 ° C.) is exceeded, the liquid injection solenoid valve 14 is operated in the opening direction. As a result, liquid refrigerant is injected into the intermediate port of the compressor 2, and the temperature of the gas refrigerant discharged from the compressor 2 decreases.
Similarly, at the time of defrosting, if the pressure detected by the low pressure sensor 18 and / or the high pressure sensor 19 exceeds a predetermined value, the suction modulating valve 39 is operated (throttled) in the closing direction. It has become. Thereby, the density of the refrigerant sucked into the compressor 2 is lowered, the circulation amount of the refrigerant is lowered, and the heating amount of the evaporator 8 is lowered. When the suction modulating valve 39 is throttled, the discharge temperature slightly increases, but this temperature increase can be prevented by slightly opening the liquid injection solenoid valve 14 as described above.

According to the refrigeration circuit 30 used in the container refrigeration unit according to the present embodiment, the discharge temperature detected by the discharge temperature sensor 15 exceeds a predetermined value (for example, 100 ° C., preferably 70 ° C.) during defrosting. In this case, the liquid injection solenoid valve 14 is operated in the opening direction, the liquid refrigerant is injected into the intermediate port of the compressor 2, and the temperature of the gas refrigerant discharged from the compressor 2 is reduced. Yes.
Thereby, the temperature of the refrigerant | coolant which passes the evaporator 8 at the time of a defrost can be lowered | hung, and generation | occurrence | production of the water vapor | steam by melting the frost adhering to the evaporator 8 can be prevented.

Further, according to the refrigeration circuit 30 used in the container refrigeration unit according to the present embodiment, the pressure of the refrigerant sucked into the compressor 2 and / or the pressure of the refrigerant discharged from the compressor 2 at the time of defrosting is a predetermined value. Is exceeded, the suction modulation valve 39 is operated in the closing direction, the density of the refrigerant sucked into the compressor 2 is lowered, the circulation amount of the refrigerant is lowered, and the heating amount of the evaporator 8 is lowered. Is configured to do.
Thereby, the frost which arrived at the evaporator 8 can be melt | dissolved slowly and reliably, the frost which arrived at the evaporator 8 can be reliably dripped on the drain pan 11 in the state of water (drain), The drain hose 13 can be reliably discharged to the outside through the drain outlet 13a.
Moreover, since the circulation amount of a refrigerant | coolant falls, the motive power of the compressor 2 can be reduced and the power saving of the compressor 2 can be achieved.

According to the sea container refrigeration unit 1 provided with the refrigeration circuit 30 used in the container refrigeration unit according to the present embodiment, the generation of water vapor due to melting of frost attached to the evaporator 8 is prevented. It is possible to prevent water droplets from adhering to the ceiling surface inside and dropping the water droplets on the luggage in the container and soiling the luggage.

Incidentally, the refrigeration circuit 30 for use in container refrigeration unit according to the present invention is not intended to be applied only to the marine container refrigeration unit 1 described above, the refrigeration unit or the like for land containers, used in a refrigeration unit for a container refrigeration Any refrigeration apparatus provided with a circuit can be applied.

It is a block diagram which shows one Embodiment of the refrigeration circuit used for the refrigeration unit for containers which concerns on this invention. It is a schematic front view of the refrigeration unit for marine containers provided with the refrigeration circuit used for the container refrigeration unit shown in FIG. It is a schematic rear view of the refrigeration unit for marine containers shown in FIG.

1 Refrigeration unit for sea containers (refrigeration equipment)
2 Compressor 3 Water-cooled condenser 4 Air-cooled condenser 7 Electronic expansion valve 8 Evaporator 14 Liquid injection solenoid valve 15 Discharge temperature sensor 18 Low pressure sensor 19 High pressure sensor 30 Refrigeration circuit used in container refrigeration unit 39 Suction modulation valve 54 Hot gas Defrost pipe 55 Discharge side refrigerant pipe

Claims (3)

A compressor that compresses a low-temperature and low-pressure gas refrigerant into a high-temperature and high-pressure gas refrigerant;
A capacitor that functions as a heat radiator that condensates and heats high-temperature and high-pressure gas refrigerant to the outside air;
An expansion valve that decompresses and expands the refrigerant that passes through it to produce a low-temperature and low-pressure refrigerant;
An evaporator that functions as an evaporator that evaporates and vaporizes low-temperature and low-pressure liquid refrigerant to remove heat from the inside air;
A refrigeration circuit used in a container refrigeration unit including a hot gas defrost pipe connecting a discharge side of the compressor and the evaporator inlet side,
A liquid injection solenoid valve is provided in the middle of the refrigerant pipe for returning the liquid refrigerant that has passed through the condenser into the compressor, and in the middle of the refrigerant pipe that connects the discharge side of the compressor and the inlet side of the condenser. A discharge temperature sensor is provided,
In the container refrigeration unit, the liquid injection solenoid valve is configured to be operated in an opening direction when the discharge temperature detected by the discharge temperature sensor exceeds 100 ° C. during defrosting. Refrigeration circuit used . Container refrigeration unit characterized by comprising comprises a refrigeration circuit used in container refrigeration unit according to claim 1. A compressor that compresses a low-temperature and low-pressure gas refrigerant into a high-temperature and high-pressure gas refrigerant;
A capacitor that functions as a heat radiator that condensates and heats high-temperature and high-pressure gas refrigerant to the outside air;
An expansion valve that decompresses and expands the refrigerant that passes through it to produce a low-temperature and low-pressure refrigerant;
An evaporator that functions as an evaporator that evaporates and vaporizes low-temperature and low-pressure liquid refrigerant to remove heat from the inside air;
A hot gas defrost pipe connecting the discharge side of the compressor and the evaporator inlet side;
A liquid injection solenoid valve provided in the middle of a refrigerant pipe for returning the liquid refrigerant that has passed through the condenser into the compressor;
A method for operating a container refrigeration unit comprising a discharge temperature sensor provided in the middle of a refrigerant pipe connecting a discharge side of the compressor and an inlet side of the condenser,
An operation method of a container refrigeration unit , wherein the liquid injection solenoid valve is operated in an opening direction when a discharge temperature detected by the discharge temperature sensor exceeds 100 ° C. during defrosting.

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