JPH07122519B2 - Refrigerator with economizer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating device in which an economizer is arranged in a refrigerant circuit, and more particularly to a refrigerating device in which a discharge gas temperature of a compressor is controlled by liquid injection.

(Prior Art) Conventionally, for example, "Refrigeration and Air Conditioning Handbook, 4th Edition, Basic Edition" (May 30, 1981, published by the Japan Refrigeration Association)
As disclosed on page 382, refrigeration systems with economizers that increase refrigeration capacity while controlling the capacity of the compressor and condenser are known. This refrigeration system with an economizer has a refrigerant circuit in which a compressor, a condenser, a liquid receiver, a main pressure reducing valve, an evaporator and a droplet separator are sequentially connected by piping, and a liquid refrigerant from the liquid receiver is reduced in pressure by a pressure reducing valve. After it is decompressed and gasified in the intercooler (economizer), it is equipped with a bypass path to bypass the intermediate pressure of the compressor, and the heat of evaporation of the refrigerant in the intercooler causes the liquid refrigerant in the main refrigerant circuit to pass over. It is designed to be cooled.

Further, in addition to this, in the above-mentioned document, after decompressing the liquid refrigerant with a liquid pipe, the gas refrigerant and the liquid refrigerant are separated by a receiver, and the gas refrigerant is bypassed to a location at an intermediate pressure of the compressor, and the low temperature There is also disclosed one provided with an economizer receiver in which only the liquid refrigerant is evaporated by the evaporator. And
With such an economizer cycle, the enthalpy change of the refrigeration cycle is increased more than when the economizer is not used, and the refrigeration effect can be increased.

(Problems to be solved by the invention) By the way, in a rotary type compressor such as a turbo type, a screw type, or a scroll type used as the above-mentioned compressor, the gap of the compressed portion is made as small as possible in terms of performance improvement. Is desirable. However, in reality, there is a limit to reducing the gap of the compressed portion, and the cause is that the compressed portion thermally expands due to the fluctuation of the discharge gas temperature and causes metal contact. In order to avoid this metal contact, a protective device (discharge pipe thermostat) that stops the compressor when the discharge gas temperature rises above a predetermined value is provided, and liquid injection is performed to stabilize the discharge gas temperature and compress it. The thermal expansion of the part is suppressed.

If you want to suppress the rise in discharge gas temperature by the above liquid injection, set the temperature set of the protective device low,
Moreover, it is necessary to always secure the liquid refrigerant for injection so that the protection device does not operate during normal operation of the compressor. For example, if there is no liquid refrigerant at the refrigerant outlet of the injection path at the time of starting the compressor, the temperature of the discharge gas will rise rapidly immediately after starting, causing the protection device to operate, and stopping the compressor.

Therefore, for example, as shown in FIG. 2, a condenser (a), a condenser (b), an automatic expansion valve (c) and an evaporator (d) are sequentially connected to a refrigerant circuit (e), and A liquid reservoir (g) such as a receiver is arranged at the refrigerant outlet of the injection path (f) that discharges a part of the refrigerant from (b) to the expansion valve (c) to a location at an intermediate pressure of the compressor (a). However, the liquid refrigerant for liquid injection is secured by the liquid refrigerant in the liquid pool (g), but since the liquid pool (g) is required in the refrigerant circuit (e), the refrigerating apparatus becomes large and the structure is large. It cannot be denied that it becomes complicated.

In the figure, (c ₁ ) is a temperature-sensing cylinder arranged in the discharge side pipe of the evaporator (d), and controls the opening of the expansion valve (c). (H) is a solenoid valve that opens and closes the injection passage (f), (i) is an automatic expansion valve that decompresses the refrigerant in the injection passage (f), and is a temperature-sensing tube (in the discharge side pipe of the compressor (a) ( The opening is adjusted by i ₁ ). (J) is a water cooler for cooling water, which is a shell-and-tube heat system in which an evaporator (d) is arranged in a closed shell (k) having a water inlet (k ₁ ) and a water outlet (k ₂ ). It consists of an exchange.

The present invention has been made in view of these points, and an object thereof is to secure a liquid refrigerant for injection by using the above-described conventional economizer without requiring liquid retention such as a receiver. Especially.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the invention according to claim (1), a part of the liquid refrigerant from the condenser of the refrigerant circuit to the pressure reducing mechanism is partially connected to the middle of the compressor by the injection path. Bypass to the place where the pressure is applied, an economizer is installed in the injection path, and the refrigerant outlet of the injection path is the secondary side of the economizer.

Specifically, as shown in FIG. 1, a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (8) are sequentially arranged in a liquid pipe (9a) and a gas pipe (9b). A main refrigerant circuit (10) connected by a pipe (9) consisting of a liquid pipe (9a) flowing from the condenser (2) of the main refrigerant circuit (10) to the main pressure reducing mechanism (3).
An injection passage (17) is provided for discharging a part of the refrigerant inside the compressor (1) by bypassing the main pressure reducing mechanism (3) and the evaporator (8), and
The injection passage (17) has a sub pressure reducing mechanism for reducing the pressure of the refrigerant flowing through the injection passage (17), and the condenser (2) to the main pressure reducing mechanism (3) based on the pressure reducing effect of the refrigerant by the sub pressure reducing mechanism. And an economizer that supercools the liquid refrigerant in the liquid pipe (9a) flowing into the tank and increases the refrigerating capacity.

Then, the injection passage (17) is connected to the liquid pipe (9a) between the economizer and the main decompression mechanism (3) so as to take out the liquid refrigerant in the liquid pipe (9) supercooled by the economizer.

Further, in the invention according to claim (2), the sub decompression mechanism is an automatic expansion valve (19) having a temperature sensing tube (19a) arranged in the discharge side gas pipe (9b) of the compressor (1). To do.

Further, in the invention according to claim (3), the economizer is an inner pipe (12) forming a part of the main refrigerant circuit (10).
And an outer pipe (13) that is arranged around the inner pipe (12) with an annular space (14) open, and the annular space (14) constitutes a part of the injection path (17). The intermediate cooler (11) has a structure and is configured to exchange heat between the refrigerant decompressed by the sub pressure reducing mechanism and the liquid refrigerant in the inner pipe (12).

(Operation) With the above configuration, in the invention according to claim (1), a part of the refrigerant in the liquid pipe (9a) flowing from the condenser (2) to the main pressure reducing mechanism (3) in the main refrigerant circuit (10). Flows into the injection path (17), this refrigerant is decompressed by the auxiliary decompression mechanism, and then the economizer liquid pipe (9a) of the main refrigerant circuit (10).
The liquid refrigerant inside is supercooled, and the refrigeration capacity is increased by this supercooling. Then, the refrigerant that has passed through the economizer is discharged to a location having an intermediate pressure of the compressor (1), and the liquid injection controls the discharge gas temperature of the compressor (1) to a constant temperature.

In that case, the injection passage (17) is connected to the liquid pipe (9a) between the economizer and the main decompression mechanism (3) so as to take out the liquid refrigerant in the liquid pipe (9a) supercooled by the economizer. Therefore, the injection path (1
In the economizer of 7), the liquid refrigerant that does not easily become a gas refrigerant in a supercooled state by the economizer always flows stably, and the liquid refrigerant ensures stable injection liquid refrigerant. Therefore, no liquid pool is required, and the circuit configuration can be simplified and the refrigeration system can be downsized.

Further, since the refrigerant in the liquid pipe (9a) after passing through the economizer is difficult to be supercooled by the economizer to be in a gas state, it may be after passing through the condenser (2) due to some influence such as an increase in ambient temperature of the device. Even if the liquid refrigerant before passing through the economizer is gasified, the liquid refrigerant after passing through the economizer is not gasified and is kept in a liquid state. Therefore, even when the refrigeration system is restarted after being stopped, the liquid refrigerant supercooled by the economizer remains, and the liquid injection can be immediately performed immediately after the startup.

In the invention according to claim (2), since the liquid refrigerant supercooled by the economizer is used as the refrigerant for injection, the amount of the refrigerant for injection can be relatively small. Therefore, the sub pressure reducing mechanism,
If the discharge pipe of the compressor (1) is an automatic expansion valve (19) having a temperature sensitive cylinder (19a), the expansion valve (19) can be downsized by the amount of the smaller amount of refrigerant, and the cost can be reduced. At the same time, its durability and reliability can be improved.

In the invention according to claim (3), the economizer is composed of an intercooler (11) including an inner pipe (12) and an outer pipe (13), and an annular space () between both pipes (12) and (13) ( Refrigerant whose pressure has been reduced by the sub-pressure reducing mechanism flows through the inner pipe (1).
2) Since the liquid refrigerant inside is supercooled, the effect as an economizer can be exhibited well.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows the overall configuration of a refrigerating apparatus (A) for cold water according to an embodiment of the present invention, in which (1) is a turbo type,
A screw type or scroll type compressor, (2) is a condenser, and (3) is an external pressure equalizing type automatic expansion valve for an evaporator as a main pressure reducing mechanism. (4) is a water cooler for cooling water, and this water cooler (4) is a closed shell having a water inlet (5) at the bottom and a water outlet (6) at the top. (7) and an evaporator (8) composed of a heat transfer tube disposed in the shell (7) so that heat can be exchanged. The compressor (1), the condenser (2), the expansion valve (3) and the evaporator (8) (heat transfer tube) are sequentially connected to the liquid pipe (9).
It is connected by a pipe (9) consisting of a) and a gas pipe (9b) so that the refrigerant can circulate, and the cold heat taken by the condenser (2) is moved to the evaporator (8) and inside the water cooler (4). The main refrigerant circuit (10) is configured to cool the water.
(3a) is a temperature-sensing cylinder provided in the outlet side gas pipe (9b) of the evaporator (8), and controls the opening of the automatic expansion valve (3).

An intermediate cooler (11) as an economizer for increasing the refrigerating capacity is provided in the liquid pipe (9a) of the main refrigerant circuit (10).
Is provided. This intercooler (11) has an inner tube (1
2) and a double tube consisting of an outer tube (13) arranged concentrically with a closed annular space (14) around the inner tube (12) inside the main refrigerant circuit (10) Is part of the. Further, of the annular space (14) between the inner pipe (12) and the outer pipe (13), the end of the annular space (14) on the condenser (2) side is connected to the intercooler (11) in the main refrigerant circuit (10). The pipe (15) is connected to the liquid pipe (9a) between the automatic expansion valve (3) and the pipe (16) is connected to the end of the expansion valve (3) at an intermediate pressure of the compressor (1). ) Respectively, and these two pipes (15),
By the annular space (14) of the intermediate cooler (16) or (16), a part of the refrigerant flowing from the condenser (2) to the automatic expansion valve (3) bypasses the expansion valve (3) and the evaporator (8). The injection passage (17) is configured so as to be discharged to a location where the intermediate pressure of the compressor (1) is reached.

Further, an electromagnetic valve (18) for controlling the opening and closing of the flow of the refrigerant in the injection path (17) in the middle of the pipe (15), and an automatic cooler as a sub pressure reducing mechanism for reducing the pressure of the refrigerant flowing in the injection path (17). Expansion valve (19) and liquid pipe (9a)
They are arranged in order from the side. The gas pipe (9b) on the discharge side of the compressor (1) has an automatic expansion valve (19) for the cooler.
A temperature-sensitive tube (19a) for controlling the opening degree of is provided. The liquid refrigerant flowing through the liquid pipe (9a) in the main refrigerant circuit (10) is cooled by the intercooler (11) to be in a supercooled state, and the liquid in the supercooled liquid pipe (9a) is A part of the refrigerant is taken out from the liquid pipe (9a) between the intercooler (11) and the automatic expansion valve (3) to the injection path (17) through the pipe (15) and decompressed by the automatic expansion valve (19). Then, the pressure-reduced refrigerant is passed through the annular space (14) of the intercooler (11).
After heat exchange with the liquid refrigerant in the inner pipe (12) therein, the liquid is injected into a portion having an intermediate pressure of the compressor (1).

Therefore, in the above embodiment, during operation of the refrigeration system (A), when the solenoid valve (18) is in the open state, the high pressure gas refrigerant discharged from the compressor (1) of the main refrigerant circuit (10) is It is liquefied in the condenser (2) and this liquid refrigerant is cooled by the intercooler (1
It is cooled in the inner pipe (12) of 1) and becomes a supercooled state. The liquid refrigerant is decompressed by the condenser expansion valve (3) and then evaporated by the evaporator (8) of the water cooler (4), and the evaporated gas refrigerant is sucked into the compressor (1) and recompressed. To be done. Then, the subcooling of the liquid refrigerant in the intercooler (11) increases the refrigeration capacity of the refrigeration system (A).

Further, a part of the supercooled refrigerant flowing in the liquid pipe (9a) from the condenser (2) to the condenser expansion valve (3) flows to the injection path (17), and this refrigerant is used for the cooler expansion valve ( After being decompressed in 19), it passes through the annular space (14) of the intercooler (11), where the liquid refrigerant in the main refrigerant circuit (10) is supercooled. Then, the refrigerant that has passed through the intercooler (11) is discharged to a location having an intermediate pressure of the compressor (1), and by this liquid injection, the compressor (1)
The discharge gas temperature of is controlled to a constant temperature.

In this embodiment, the injection passage (17) is connected to the main refrigerant circuit (10) so as to take out the liquid refrigerant in the liquid pipe (9a) supercooled by the intermediate cooler (11). ) And the automatic expansion valve (3) are connected to the liquid pipe (9a), the liquid refrigerant supercooled by the intercooler (11) is always stable in the injection path (17). As a result, the liquid refrigerant is retained in the annular space (14) of the intercooler (11), and the liquid refrigerant ensures the injection liquid refrigerant. Therefore, no liquid pool such as a receiver is needed to store the injection refrigerant,
The omission of this liquid pool simplifies the circuit configuration of the refrigeration system (A) and downsizes the refrigeration system (A), while stably controlling the discharge gas temperature by liquid injection to improve the durability of the compressor (1). , Reliability can be improved.

Further, in the main refrigerant circuit (10), since the liquid refrigerant supercooled by the intercooler (11) is used as the liquid refrigerant for injection, the cooling effect by the injection of the supercooled refrigerant becomes large, Therefore, the amount of the injection liquid refrigerant is relatively small. Therefore, the amount of refrigerant decompressed by the cooler automatic expansion valve (19) also decreases, and the expansion valve (19) can be downsized by the smaller amount of the refrigerant, thereby reducing the cost and expanding the expansion valve (19). ) Durability and reliability can be improved.

Further, the refrigerant in the liquid pipe (9a) after passing through the intercooler (11) is difficult to be supercooled by the intercooler (11) to be in a gas state. Due to the influence, even when the liquid refrigerant after passing through the condenser (2) and before passing through the intercooler (11) is gasified, it is not gasified and is kept in a liquid state. For this reason, the supercooled liquid refrigerant remains in the intercooler (11) even when the refrigeration system (A) is restarted after it is stopped. Therefore, liquid injection is immediately performed immediately after the refrigeration system (A) is started. It will be possible.

(Effect of the invention) As described above, according to the invention according to claim (1), when liquid injection is performed for controlling the discharge gas temperature of the compressor, the liquid refrigerant reaching the pressure reducing mechanism of the main refrigerant circuit. By using an economizer that supercools the refrigerant, the liquid refrigerant for injection is taken out from the secondary side of the economizer. It can be stably secured as a liquid refrigerant that is difficult to gasify in the cooled state, and therefore, the reliability of the compressor can be improved while achieving downsizing of the refrigerator and simplification of the refrigerant circuit configuration.

Further, according to the invention of claim (2), since the auxiliary decompression mechanism for decompressing the refrigerant in the injection path is constituted by the automatic expansion valve having the temperature sensing cylinder on the compressor discharge side, Since the amount of refrigerant to be expanded is small, the expansion valve can be miniaturized, cost reduction and durability of the expansion valve,
It is possible to improve reliability.

Further, according to the invention of claim (3), since the economizer is composed of an intercooler having a double pipe structure including an inner pipe and an outer pipe, the annular space between the two pipes is decompressed by the auxiliary decompression mechanism. It is possible to cause the refrigerant to flow, and to supercool the liquid refrigerant in the inner pipe by this refrigerant, so that the effect as an economizer can be exhibited well.

[Brief description of drawings]

FIG. 1 is a refrigerant piping system diagram showing an embodiment of the present invention.
FIG. 2 is a view corresponding to FIG. 1 showing a conventional example. (A) -Refrigerator (1) -Compressor (2) -Condenser (3) -Expansion valve (main decompression mechanism) (8) -Evaporator (9) -Piping (9b) ... … Gas pipe (10) …… Main refrigerant circuit (11) …… Intercooler (economizer) (12) …… Inner pipe (13) …… Outer pipe (14) …… Annular space (17) …… Injection path (19) …… Expansion valve (sub pressure reducing mechanism) (19a) …… Temperature sensing tube

Claims (3)

[Claims] 1. A compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (8) are connected by a pipe (9) consisting of a liquid pipe (9a) and a gas pipe (9b) in order. And a part of the refrigerant in the liquid pipe (9a) flowing from the condenser (2) of the main refrigerant circuit (10) to the main pressure reducing mechanism (3). ) And evaporator (8) by-pass compressor (1)
An injection path (17) for discharging the intermediate pressure of the injection path (17), the injection path (17), the auxiliary pressure reducing mechanism for depressurizing the refrigerant flowing through the injection path (17), An economizer for supercooling the liquid refrigerant in the liquid pipe (9a) flowing from the condenser (2) to the main pressure reducing mechanism (3) to increase the refrigerating capacity based on the pressure reducing effect is provided, and the injection path ( 17) is characterized in that it is connected to the liquid pipe (9a) between the economizer and the main decompression mechanism (3) so as to take out the liquid refrigerant in the liquid pipe (9a) supercooled by the economizer. Refrigerator with economizer. 2. The sub decompression mechanism is an automatic expansion valve (19) having a temperature sensing cylinder (19a) arranged in the discharge side gas pipe (9b) of the compressor (1). The refrigeration apparatus with an economizer according to the item (1). 3. The economizer is arranged with an inner pipe (12) forming a part of a main refrigerant circuit (10) and an annular space (14) around the inner pipe (12). (14) with the outer pipe (13) that forms part of the injection path (17)
The intermediate cooler (11) having a heavy pipe structure and for exchanging heat between the refrigerant decompressed by the auxiliary decompression mechanism and the liquid refrigerant in the inner pipe (12). ) Refrigeration equipment with an economizer as described.