JPH04174259A - Low and high temperature medium cooling refrigerator - Google Patents

Abstract

PURPOSE:To reduce capacity of a compressor of a refrigerating cycle by coupling both ends of a cooling circuit in which a first switching valve, a refrigerant cooler using natural cold, a second switching valve are sequentially interposed at the upper side of a low pressure receiver. CONSTITUTION:If temperature of heat medium air to be cooled is, for example, higher than natural cold temperature, a compressor 20 is stopped, a first switching valve 33, a second switching valve 35 are opened, and then refrigerant is circulated in a passage of an evaporator 28, a first low pressure gas line 30, a low pressure receiver 24, a refrigerant cooler 34, the receiver 34, a liquid pump 29 and the evaporator 28. In this case, the refrigerant is heat exchanged with natural cold such as the atmosphere, well water, etc., by the cooler 34, and the medium air can be reduced at its temperature. That is, the capacity of the compressor 20 of a refrigerating cycle can be reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a refrigeration system for cooling both a low-temperature medium and a high-temperature medium for effectively cooling not only low-temperature ranges but also high-temperature ranges. be.

[Conventional technology]

This type of refrigeration equipment for cooling both low-temperature medium and high-temperature medium is
For example, an environmental maintenance room that reproduces weather conditions.

It is used to reproduce various weather conditions on Earth, such as in automobile-related test laboratories and plant laboratories. This environmental maintenance room has a wide control range, for example, reproduces temperature conditions in a wide range of -40°C to +50°C, and also has a humidity limit of 90% at high temperatures such as +50°C. Sometimes high conditions are reproduced.

Conventionally, as a refrigeration system for cooling both a low-temperature medium and a high-temperature medium used in such an apparatus, one using a direct expansion refrigerator is known.

This will be explained based on FIG.

A refrigeration system using this direct expansion refrigerator includes a compressor (refrigerator) 1, a condenser 2, an expansion valve 3, a low pressure receiver 4, a liquid pump 5, and an evaporator 6. are connected by a high-pressure gas line 7, the condenser 2 and low-pressure receiver 4 are connected by a high-pressure liquid line 8 via an expansion valve 3, and the low-pressure receiver 4 and evaporator 6 are connected by a liquid pump 5. By connecting the evaporator 6 and the low pressure receiver 4 with the first low pressure gas line 10, and connecting the low pressure receiver 4 and the compressor 1 with the second low pressure gas line 11. It forms a refrigeration cycle.

First, the refrigerant in the gas state is compressed into high pressure gas by the compressor 1,
This compressed high pressure gas is sent to the condenser 2 via the high pressure gas line 7, where it is condensed and liquefied. This is sent to the low pressure receiver 4 via the high pressure gas line 8. An expansion valve 3 provided in front of the low-pressure receiver 4 expands the high-pressure liquid to make it a cold liquid and at the same time partially vaporizes it. The cold liquid sent to the low pressure receiver 4 is sent to the evaporator 6 by the liquid pump 5 via the low pressure liquid line 9.

The gas leaving the evaporator 6 returns to the low pressure receiver 4 via a first low pressure gas line 10, and a portion of the cold gas is sent via a second low pressure gas line 11 to the compressor 1, which is then connected to the circuit as described above. form.

Thereby, the heat medium air to be cooled passing through the evaporator 6 can be cooled.

[Problem to be solved by the invention]

In conventional refrigeration systems, even when the temperature and humidity of the heat medium air to be cooled is higher than the temperature and humidity of the natural world, such as outside air or well water, the refrigeration cycle is operated to perform cooling.

However, when the temperature and humidity of the heat transfer medium air to be cooled is high and high humidity, the refrigerant temperature cannot be raised to a high temperature during normal refrigeration cycle operation, so the evaporator 6 constituting the air cooler does not cause excessive depletion. Humidity occurs, the amount of sensible heat cooling becomes insufficient, and not only does the refrigeration system become larger than necessary, but running costs also increase because the compressor 1 is operated.

The present invention has been made to solve the above-mentioned problems, and its purpose is to condense and liquefy the refrigerant using inexpensive cold heat from outside air, well water, etc. when the heat medium air to be cooled is high temperature and high humidity. It is an object of the present invention to provide a refrigeration device for cooling both a low-temperature medium and a high-temperature medium, which can cool heat medium air to be cooled without causing excessive dehumidification.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a compressor, a condenser, an expansion valve, a low pressure receiver, a liquid pump, and an evaporator,
The compressor and condenser are connected by a high pressure gas line, the condenser and low pressure receiver are connected by a high pressure liquid line via an expansion valve, and the low pressure receiver and evaporator are connected by a liquid pump. In a refrigeration system in which a refrigeration cycle is formed by connecting a liquid line, an evaporator and a low pressure receiver by a first low pressure gas line, and a low pressure receiver and a compressor by connecting a second low pressure gas line. , both ends of a cooling circuit are connected to the upper side of the low-pressure receiver, in which a first switching valve, a refrigerant cooler that cools the refrigerant using natural cooling energy, and a second switching valve are installed in this order.

[For production]

In the present invention, when the temperature of the heat medium air to be cooled in the evaporator is lower than the natural cooling temperature in the refrigerant cooler,
The first switching valve and the second switching valve are closed, and the compressor is driven to transfer the refrigerant to the compressor → condenser → expansion valve → low pressure and sheaver →
The liquid is circulated through the following path: liquid pump → evaporator → low-pressure sheaver → compressor.

As a result, a refrigeration cycle is formed, and the heat medium air to be cooled is cooled by the evaporator.

On the other hand, if the temperature of the heat medium air to be cooled in the evaporator is higher than the natural cooling temperature in the refrigerant cooler, the compressor is stopped, the first switching valve and the second switching valve are opened, and the refrigerant is transferred to the evaporator →
It is circulated through the first low pressure gas line -> low pressure receiver - refrigerant cooler - low pressure receiver liquid punchy evaporator.

As a result, the refrigerant exchanges heat with the heat medium air to be cooled in the evaporator and evaporates (vaporizes), and this refrigerant becomes vapor.
The refrigerant cooler exchanges heat with natural cold heat such as outside air or well water, and cools and condenses it.

In this case, if the refrigerant gas guided from the evaporator to the low-pressure receiver contains refrigerant liquid and refrigeration oil, the refrigerant gas and refrigerant liquid will be separated in the low-pressure receiver.

The refrigerant oil is separated from the refrigerant gas, and only the refrigerant gas is guided to the refrigerant cooler via the cooling circuit.

Also, when switching between a refrigeration system using a compressor and a cooling system using a refrigerant cooler, for example, when switching from the former to the latter, a low pressure receiver is located between the first low pressure gas line and the cooling circuit. Since the low-pressure receiver performs the function of gas-liquid separation, only the refrigerant gas is transported to the refrigerant cooler,
In a refrigerant cooler, refrigerant gas undergoes a phase change and is condensed into refrigerant liquid.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a refrigeration system for cooling both a low-temperature medium and a high-temperature medium according to an embodiment of the present invention.

In FIG. 1, 20 is a compressor, and this compressor 20 is
It is connected to a condenser 22 via a high pressure gas line 21. This condenser 22 is connected to the source side of a low pressure receiver 24 via a high pressure liquid line 23 . This high pressure liquid line 2
3 is provided with a third switching valve 25 and an expansion valve 26. The source side of this low pressure receiver 24 is connected to an evaporator 28 via a low pressure liquid line 27. This low pressure liquid line 2
7 is provided with a liquid pump 29.

The outlet side of the evaporator 28 and the gas side of the low pressure receiver 24 are
They are connected via a first low pressure gas line 30.

Both ends of a cooling circuit 320 are connected to the upper side 31 of the low-pressure receiver 24 . This cooling circuit 32 includes a first switching valve 33. Refrigerant cooler 34. A second switching valve 35 is interposed in order from the low pressure receiver 24 side. The refrigerant cooler 34 cools the refrigerant using natural cooling heat such as outside air or well water.

Further, the low pressure receiver 24 and the compressor 20 are connected via a second low pressure gas line 36.

In this example, the temperature of the heat medium air to be cooled is =20°
It is applied in the range of C to +50°C and the humidity is in the range of 30% to 90%, and the operation of this embodiment will be explained as follows.

First, when the temperature of the heat medium air to be cooled in the evaporator 28 is lower than the natural cooling temperature in the refrigerant cooler 34, normal operation as shown in FIG. 2 can be performed.

In order to achieve this normal operation, the first switching valve 33 and the second switching valve 35 are closed, and the third switching valve 25 is opened to form a circulation path shown by a bold line.

In this normal operation, high-pressure gas compressed by the compressor 20 is sent to the condenser 22 via the high-pressure gas line 21, where it is condensed and liquefied. This is sent to the low pressure receiver 24 via the high pressure liquid line 23. An expansion valve 26 provided in front of the low pressure receiver 24 expands the high pressure liquid to make it a cold liquid and at the same time partially vaporizes it. Low pressure receiver 2
The cold liquid sent to 4 is sent to the evaporator 28 by a liquid pump 29 via a low pressure liquid line 27.

In the second evaporator 28, the gas is gasified by exchanging heat with the heat medium air to be cooled, and the gas is returned from the evaporator 28 to the low pressure receiver 24 via the first low pressure gas line 30, and the cold gas is transferred to the second low pressure gas line. 36 to the compressor 20,
It cycles through the circuit as described above.

Thereby, a refrigeration cycle is formed, and the heat medium air to be cooled is cooled by the evaporator 28.

On the other hand, when the temperature of the heat medium air to be cooled is higher than the natural cooling temperature, operation as shown in FIG. 3 can be performed.

To achieve this operation, the compressor 20 is stopped and the first switching valve 33. By opening the second switching valve 35, a circulation path shown in bold line is formed.

This circulation path does not use the compressor 20, but instead uses the refrigerant cooler 34.
In this cooling cycle, the refrigerant circulates along the path of evaporator 28 → first low pressure gas line 30 → low pressure receiver 24 → refrigerant cooler 34 → low pressure receiver 24 → liquid pump 29 → evaporator 28.

As a result, the refrigerant exchanges heat with the heat medium air to be cooled in the evaporator 28 and evaporates (vaporizes), and this yellowish refrigerant exchanges heat with natural cooling heat such as outside air or well water in the refrigerant cooler 34. , cooled and condensed. For example, when using outside air at 32°C as natural cooling heat, the temperature of the heat medium air to be cooled can be set to about 45°C, and the
When using well water at °C, the temperature of the cooled heat medium air should be set to 3
It can also be set to about 0°C.

Here, for the purpose of improving the heat transfer characteristics and efficiency of the evaporator 28, excess refrigerant liquid is supplied to the evaporator 2 by the liquid pump 29, so that the first low pressure gas line 3.0 is supplied with refrigerant liquid. A portion of the refrigerating machine oil that flows into the refrigerant liquid and dissolves in the refrigerant liquid may also separate and become oil droplets due to evaporation of the refrigerant. In this case, the refrigerant gas, refrigerant liquid, and refrigerating machine oil are separated in the low-pressure receiver 24, and only the refrigerant gas is sent to the cooling circuit 3.
The refrigerant is guided to the refrigerant cooler 34 via the refrigerant cooler 34.

When continuously increasing or decreasing the temperature and humidity of the heat medium air to be cooled, it is necessary to appropriately switch between the refrigeration system using the compressor 20 and the cooling system using the refrigerant cooler 34.

For example, in the case of switching from the former to the latter (state in Figure 2 →
3), after flowing well water etc. into the refrigerant cooler 34 in advance to lower the temperature of the refrigerant cooler 34 and standby in a usable state, the first switching valve 33 and the second switching valve 35 are turned on. The refrigerant cooler 34 is put into operation by switching from closed to open, and then the compressor 20 of the refrigeration system is stopped. Therefore, switching between the refrigeration system and the cooling system is performed smoothly, and temperature fluctuations in the evaporator 28 are minimized.

In addition, when switching from a cooling system using the refrigerant cooler 34 (shown in FIG. 3) to a refrigeration system using the compressor 20 (shown in FIG. 2), the compressor 20 is started, and the first switching valve 33 ．． If the second switching valve 35 is switched from open to closed, the third
The state shown in the figure changes to the state shown in FIG.

According to the above configuration, when the temperature of the heat medium air to be cooled is higher than the natural cooling temperature, the temperature of the heat medium air to be cooled can be lowered by using the natural cooling heat without using the refrigeration cycle. can.

In this case, even if the heat medium air to be cooled is at a high temperature, the heat medium air to be cooled can be cooled while maintaining humidity (without causing excessive dehumidification).

In addition, if the temperature and humidity of the heat transfer medium air to be cooled is high and humid, the normal refrigeration cycle is not used as described above.
In the evaporator 28, the amount of sensible heat cooling due to excessive M moisture as described in the conventional example does not decrease, and therefore the capacity of the compressor 20 for each cycle of refrigeration can be reduced.
Running costs due to stopping the compressor 20 can also be reduced.

Here, if we widen the operating range using natural cooling,
The above-mentioned effects can be made more noticeable.

The range of such operation using natural cooling depends on the temperature field of natural cooling, the heat transfer area of the refrigerant cooler 34, the capacity of the liquid pump 29, etc.

When the refrigeration cycle is not used, the vaporized refrigerant is cooled and condensed by exchanging heat with natural cold heat such as outside air or well water in the refrigerant cooler 34.
Even if the refrigerant gas led from the evaporator 28 to the first low-pressure gas line 30 contains refrigerant liquid and refrigerating machine oil as described above, the refrigerant gas is separated from the refrigerant liquid and refrigerating machine oil in the low-pressure receiver 24, Only the refrigerant gas can be led to the refrigerant cooler 34 via the cooling circuit 32. Therefore, a decrease in cooling efficiency in the refrigerant cooler 34 can be prevented. Thereby, the capacity of the refrigerant cooler 34 can be reduced, and the consumption of well water and the like can be reduced.

When switching between a refrigeration system using the compressor 20 and a cooling system using the refrigerant cooler 34, for example, when switching from the former to the latter, the first low pressure gas line 30
Since the low pressure receiver 24 is located between the cooling circuit 32 and the cooling circuit 32, only the refrigerant gas is conveyed to the refrigerant cooler 34, where the refrigerant gas undergoes a phase change and is condensed into a refrigerant liquid to provide refrigerant cooling. There is no reduction in cooling efficiency in the cooling circuit 34, and temperature fluctuations at the time of switching in the cooling circuit 32 can be minimized.

In this example, the temperature of the heat medium air to be cooled is in the range of 120°C to 50°C, and the humidity is 30% to 90%.
Although an example has been described that is applicable within the range, it is needless to say that the range is not limited to this range.

〔Effect of the invention〕

As described above, according to the refrigeration system for cooling both low-temperature medium and high-temperature medium according to the present invention, when the temperature of the heat medium air to be cooled is higher than the natural cooling temperature, the refrigeration cycle is not used.
By utilizing natural cooling energy, the temperature of the heat medium air to be cooled can be lowered.

In this case, even if the heat medium air to be cooled is at a high temperature, the heat medium air to be cooled can be cooled while maintaining humidity (without causing excessive dehumidification).

In addition, if the temperature and humidity of the heat transfer medium air to be cooled is high and humid, the normal refrigeration cycle is not used as described above.
In the evaporator, the amount of sensible heat cooling does not decrease due to excessive dehumidification as described in the conventional example, and therefore the capacity of the compressor in the refrigeration cycle can be reduced, reducing running costs due to compressor stoppage. can also be reduced.

When the refrigeration cycle is not used, the vaporized refrigerant is cooled and condensed by exchanging heat with natural cold heat such as outside air or well water in a refrigerant cooler. Even if the refrigerant gas led to the low-pressure receiver contains refrigerant liquid and refrigerating machine oil, the refrigerant gas, refrigerant liquid, and refrigerating machine oil are separated in the low-pressure receiver, and only the refrigerant gas is transferred to the refrigerant through the cooling circuit. It can be led to a cooler. Therefore, a decrease in cooling efficiency in the refrigerant cooler can be prevented.

Furthermore, when switching between a refrigeration system using a compressor and a cooling system using a refrigerant cooler, for example, when switching from the former to the latter, a low pressure receiver is installed between the first low pressure gas line and the cooling circuit. Because the low pressure receiver performs the function of gas-liquid separation, only the refrigerant gas is conveyed to the refrigerant cooler, in which the refrigerant gas undergoes a phase change and is condensed into refrigerant liquid, and the refrigerant gas in the refrigerant cooler is There is no reduction in cooling efficiency, and temperature fluctuations at the time of switching in the cooling circuit can be minimized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a refrigeration system for cooling both a low-temperature medium and a high-temperature medium according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a refrigeration cycle when the temperature of the heat medium air to be cooled is lower than the natural cooling heat in the refrigeration system for cooling both low temperature medium and high temperature medium. FIG. 3 is an explanatory diagram showing a cooling cycle when the temperature of the heat medium air to be cooled is higher than the natural cooling heat in the refrigeration system for cooling both a low temperature medium and a high temperature medium. FIG. 4 is a block diagram showing a refrigeration system using a conventional direct expansion refrigerator. [Explanation of symbols of main parts] 20... Compressor 21... High pressure gas line 22... Condenser 23... High pressure liquid line 24... Low pressure receiver 26... Expansion valve 27... -Low pressure liquid line 28...evaporator 29...liquid pump 30...first low pressure gas line 32...cooling circuit 33...first switching valve 34...refrigerant cooler 35... Second switching valve 36...second low pressure gas line.

Claims (1)

[Claims] (1) Equipped with a compressor, a condenser, an expansion valve, a low-pressure receiver, a liquid pump, and an evaporator, the compressor and condenser are connected by a high-pressure gas line, and the condenser and low-pressure receiver are connected with an expansion valve. The low pressure receiver and the evaporator are connected by a low pressure liquid line via a liquid pump, the evaporator and the low pressure receiver are connected by a first low pressure gas line, and the low pressure receiver and the compressor are connected by a first low pressure gas line. In a refrigeration system in which a refrigeration cycle is formed by connecting a machine and a second low pressure gas line,
A low-temperature medium characterized in that both ends of a cooling circuit are connected to the upper side of a low-pressure receiver, in which a first switching valve, a refrigerant cooler that cools the refrigerant using natural cooling energy, and a second switching valve are installed in this order. and refrigeration equipment that can also be used as a high-temperature medium.