JPH0263146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cooling device used for a vehicle cooling device, a room cooler, or the like.

[Technical background of the invention]

Conventionally, in cooling equipment, in order to improve the efficiency of the evaporator, refrigerant is divided into multiple pipes through a flow divider, and then introduced into the evaporator, which is then separated from the draft air sent from the ventilation fan. It is designed to perform heat exchange.

FIG. 3 shows an example of a refrigeration cycle in a conventional cooling system. Gaseous refrigerant that has been compressed by a compressor 1 and heated up is introduced into a condenser 2, and is exchanged with ventilation A by a fan 3. The liquid is then cooled, liquefied, and sent to the liquid receiver 4.

The liquefied refrigerant that has entered the receiver 4 is separated into gas and liquid due to the difference in specific gravity, and the liquid refrigerant is pumped up through a pipe with one end open at the bottom and transferred to the supercooling heat exchanger 5.
will be introduced in

The supercooling heat exchanger 5 is arranged upstream of the condenser 2 with respect to the direction of the draft A flowing by the fan 3 described above, and the liquefied refrigerant flowing through the supercooling heat exchanger 5 is It is supercooled by heat exchange with A.

The liquefied refrigerant supercooled by the supercooling heat exchanger 5 is introduced into the expansion valve 6, and after being depressurized and atomized,
The water passes through the flow divider 7, is divided into a large number of pipe lines 8a to 8n, and is sent to the evaporator.

The ventilation B generated by the ventilation fan 10 is cooled by heat exchange with the refrigerant flowing in the evaporator 9, and is used as cold air to cool the interior of the vehicle or the room.

On the other hand, the refrigerant heated by the ventilation B while flowing through the evaporator 9 evaporates, collects at the outlet of the evaporator 9, and flows back to the compressor 1 through the pipe 11 to complete the refrigeration cycle. .

Note that a temperature sensing cylinder 12 is attached to the outlet of the evaporator 9 to detect the temperature of the refrigerant flowing into the pipe line 11.

The expansion valve 6 adjusts its opening degree based on the temperature signal from the temperature sensing tube 12 and the pressure signal. Normally, the opening degree of the expansion valve 6 is adjusted so that the temperature of the thermosensor cylinder 12 is overheated by about 5 degrees Celsius relative to the saturation pressure in the evaporator. The valve is set to close.

Therefore, if the refrigerant flows too much and evaporation in the evaporator 9 is not completed, the refrigerant will flow through the temperature sensing tube 12 in a saturated state, and the degree of superheat will be lower than the above-mentioned 5°C. becomes smaller, and the expansion valve 6 is throttled to reduce the refrigerant flow rate.

On the other hand, if the expansion valve 6 is throttled too much and evaporation of the refrigerant is completed in the middle of the evaporator 9, the degree of superheat will exceed the above-mentioned set temperature, and the expansion valve 6 will operate in the opening direction. , increase the refrigerant flow rate.

By opening and closing the expansion valve 6 described above, the refrigerant is appropriately evaporated in the evaporator 9, and cooling air is supplied.

FIG. 4 shows the refrigeration cycle of FIG. 3 on a Mollier diagram, where i represents enthalpy, p represents pressure, and t represents temperature.

In the figure, a indicates the state of the suction gas at the inlet of the compressor 1, and as a result of the refrigerant being compressed by the compressor 1, at the outlet, the enthalpy i, pressure p, temperature t is getting higher.

The refrigerant fed into the condenser 2 in the state b above is gradually cooled while flowing through the condenser, and when it passes the saturation point c, it starts to liquefy. When further cooled, most of the refrigerant liquefies at the saturation end point d,
Enters liquid receiver 4.

From the liquid receiver 4, only the liquid phase portion is sent into the supercooling heat exchanger 5, where it is supercooled and transferred to the supercooling heat exchanger 5.
At the exit, the state is e.

The supercooled refrigerant leaving the supercooling heat exchanger 5 is passed through the expansion valve 6.
The gas is introduced into the air flow pipe, the pressure is reduced by the throttling action, the gas and liquid become a two-phase flow during expansion, and the flow is sent to the flow divider 7 in the state f.

The refrigerant divided into each of the pipes 8a to 8n by the flow divider 7 completes evaporation while flowing through the evaporator 9,
After point h, the temperature becomes 100% gas phase, the temperature rises, the temperature returns to the inlet of the compressor 1 in state a, and the refrigeration cycle is repeated in the same manner.

Next, the state of f in the refrigeration cycle will be explained using the case of a bus cooling system using an air-cooled condenser 2 shown in FIG. 3 as an example.
At 35℃, the condensation temperature of condenser 2 is 60℃, the pressure is about 15Kg/cm ² G, and the amount of cooling by supercooling heat exchanger 5 is
15 degrees, and the refrigerant evaporation temperature and pressure are approximately 7 degrees Celsius.
It is 2.9Kg/cm ² G.

The refrigerant temperature at the inlet of the expansion valve 6 is 45° C. due to supercooling, and the refrigerant temperature at the outlet of the expansion valve 6 is wet steam with a gas weight of about 25%. The pressure at this time was 2.9 kg/cm ² in gauge pressure, and the refrigerant was a gas/liquid two-phase flow in which 25% by weight was gasified.

The volume of refrigerant is 0.729/Kg in liquid state at 7℃,
In the gas state, it is 45.83/Kg, so liquid volume: 0.729 x 0.75 = 0.546 gas volume: 45.83 x 0.25 = 11.45, and the volume ratio is 1 liquid volume to 21 gas volume.

In this two-phase flow of gas and liquid, where the amount of gas is overwhelmingly large compared to the amount of liquid, the refrigerant liquid sticks to the pipe wall at bends and branch points of the pipe due to gravity, inertial force, surface tension, etc. This tends to cause uneven flow.

Note that g in FIG. 4 shows the case where supercooling is not performed, and in this case, the gaseous phase component of the refrigerant will account for 35% by weight, so unevenness of the refrigerant is more likely to occur.

[Problems with background technology]

As mentioned above, in conventional cooling systems, when the refrigerant is divided into multiple pipes using a flow divider, the liquid phase portion of the refrigerant is only 1/20 to 1/30 by volume, so the vortex of the flow is generated. Due to surface tension on the walls of the pipes and pipes, the distribution from the flow divider tends to be uneven, making it difficult to uniformly distribute the refrigerant to a large number of pipes.

If an imbalance occurs in the refrigerant distributed to each pipe, pipes with a large amount of liquid will still be saturated at the outlet, and pipes with a small amount of liquid will still be saturated, even though some liquid remains. A situation arises in which the gas is already superheated at the outlet end.

In such a case, if the thermosensor cylinder 12 detects a saturated state with a superheat degree of 0 and throttles the expansion valve 6, the amount of refrigerant in other pipes will also decrease, so the evaporator 9
The disadvantage was that the performance of the system was significantly reduced.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks in the background art, and provides a cooling device that can achieve a large amount of supercooling of the refrigerant and furthermore evenly distributes the refrigerant to prevent a decrease in efficiency. The purpose is to

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a cooling device that includes a compressor, a condenser that condenses refrigerant compressed by the compressor and heated up, and a liquid receiver that receives the refrigerant sent out from the condenser. a heat exchanger for subcooling the liquefied refrigerant sent out from the liquid receiver, a flow divider for dividing the liquefied refrigerant sent out from the heat exchanger into a plurality of pipes, and a flow divider for introducing the liquefied refrigerant through the pipes. a refrigeration circuit consisting of an evaporator that evaporates refrigerant; a condenser that cools and condenses the refrigerant gas sent out from the gas phase portion of the liquid receiver; and an expansion circuit that expands the refrigerant exiting the condenser. and a second refrigeration circuit comprising: a second refrigeration circuit that returns the refrigerant that has passed through the heat exchanger and supercooled the refrigerant on the first refrigeration circuit side to the inlet side of the compressor; It is characterized by

[Embodiments of the invention]

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

FIG. 1 illustrates a refrigeration cycle of a cooling device to which the present invention is applied, and the same members as in FIG. 3 are indicated by the same symbols.

In FIG. 1, a high-pressure gaseous refrigerant that has been compressed by a compressor 1 and heated up is introduced into a condenser 2, cooled by heat exchange with ventilation A, liquefied, and sent to a liquid receiver 4. entered.

The refrigerant that has entered the liquid receiver 4 is separated into gas and liquid due to the difference in specific gravity, and the liquid refrigerant is pumped up through a pipe that is open at one end and introduced into the supercooling heat exchanger 20 .

The liquefied refrigerant supercooled by the supercooling heat exchanger 20 is introduced into the expansion valve 6, and after being depressurized, passes through the flow divider 7, and is divided into multiple pipes 8a to 8n to reach the evaporator 9. sent.

The ventilation B generated by the ventilation fan 10 is cooled by heat exchange with the refrigerant flowing in the evaporator 9, and is used as cold air to cool the interior of the vehicle or the room.

On the other hand, the refrigerant heated by the ventilation B while flowing through the evaporator 9 evaporates, collects at the outlet of the evaporator 9, and flows back to the compressor 1 through the pipe 11 to complete the refrigeration cycle. .

The above-mentioned circuit is referred to as a first refrigeration circuit in the present invention.

On the other hand, a condenser 22 is connected to a conduit 21 that opens into the upper gas portion of the liquid receiver 4 . This condenser is placed upstream of the cooling air A with respect to the condenser 2 of the first refrigeration circuit, and the refrigerant fed into the condenser 22 is cooled and liquefied by heat exchange with the cooling air A. Ru. This liquefied refrigerant is introduced into an expansion device consisting of an expansion valve 23 or a capillary tube, and after being depressurized and expanded, the refrigerant on the first circuit side is supercooled in the subcooling heat exchanger 20, and the refrigerant itself is heated and evaporated. , conduit 2
4 and flows into the compressor 1.

In the present invention, from the liquid receiver 4 to the pipe line 21,
condenser 22, expansion valve 23, subcooling heat exchanger 20,
The circuit leading to the compressor 1 via the pipe line 24 is referred to as a second refrigeration circuit.

FIG. 2 shows the refrigeration cycle of FIG. 1 on a Mollier diagram. As a result of the refrigerant in state a being compressed by compressor 1, at its outlet, enthalpy i, pressure p, The temperature t is increasing in both cases.

The refrigerant fed into the condenser 2 in the state b above is gradually cooled while flowing through the condenser, and begins to liquefy after passing the saturation point c. At the outlet of the condenser 2, most of the refrigerant liquefies as shown in d, and the liquid receiver 4
to go into.

Only the liquid phase portion is sent from the liquid receiver 4 into the supercooling heat exchanger 20, and is supercooled from d to e.
The supercooled refrigerant that exits the supercooling heat exchanger 20 in state e is introduced into the expansion valve 6, and its pressure is reduced by its throttling action, changing from e to f.

The refrigerant divided into each pipe line 8a to 8n is transferred to an evaporator 9.
Evaporation completes while flowing through the
The inlet of the compressor 1, which is superheated as 100% refrigerant,
That is, the state returns to state a, and the refrigeration cycle is repeated in the same manner thereafter.

As described above, in the second refrigeration circuit of the cooling device of the present invention, the refrigerant taken out from the upper gas portion of the liquid receiver 4 is cooled and liquefied in the condenser 22 of the second refrigeration circuit, and the refrigerant is liquefied by the expansion valve 23. The pressure is reduced by heat exchanger 2.
After the refrigerant in the first refrigeration circuit is subcooled within the refrigeration system 0, it is sucked into the compressor 1.

Note that the suction port to the compressor of the second refrigeration circuit is the lowest pressure part of the pipe line 11. Thereby, the refrigerant saturation temperature of the second refrigeration circuit in the heat exchanger 20 can be set to the lowest temperature. Therefore, the liquefied refrigerant flowing into the expansion valve 6 of the first refrigeration circuit can be cooled to the evaporation temperature of the first refrigeration circuit.

In this way, in the present invention, since the temperature of the refrigerant flowing into the expansion valve 6 is cooled in advance to the evaporation temperature of the evaporator 9, a gas phase is not generated even if the pressure is reduced by the expansion valve 6, and even if However, the amount is extremely small. Therefore, the flow in the flow divider 7 is evenly divided.

〔Effect of the invention〕

As mentioned above, in the cooling device of the present invention, the temperature of the refrigerant flowing into the flow divider is lowered to the evaporation temperature in the evaporator, so the generation of gas phase is minimal, and most of the refrigerant remains in the liquid phase. flows into the flow divider.

Therefore, the amount of refrigerant distributed from the flow divider to each pipe is made uniform, and the evaporation of the refrigerant is completed in all the pipes at the evaporator outlet, thereby improving the heat exchange efficiency of the evaporator.
This makes it possible to downsize the evaporator, which reduces cost and weight, and provides significant energy savings.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the refrigeration circuit of the cooling device of the present invention, FIG. 2 is its Mollier diagram, and FIG.
The figure is a system diagram illustrating a conventional cooling device, and FIG. 4 is a Mollier diagram thereof. 1...Compressor, 2,22...Condenser, 3,10
... Ventilation fan, 4 ... Liquid receiver, 5, 20 ... Supercooling heat exchanger, 6, 23 ... Expansion valve, 7 ... Divider, 8a to 8n ... Pipe line, 9 ... Evaporator , 12...
...Thermosensitive tube, 20...Heat exchanger.

Claims (1)

[Claims] 1. A compressor, a condenser that condenses refrigerant compressed and heated by the compressor, a liquid receiver that receives the refrigerant sent from the condenser, and a liquid receiver that receives the refrigerant from the liquid receiver. A heat exchanger that subcools the liquefied refrigerant sent out, a flow divider that divides the liquefied refrigerant sent out from the heat exchanger into a plurality of pipes, and an evaporator that evaporates the refrigerant introduced through the pipes. a first refrigeration circuit comprising; a condenser that cools and condenses refrigerant gas sent from the gas phase portion of the liquid receiver; an expansion device that expands the refrigerant exiting the condenser; and the heat exchanger. a second refrigeration circuit consisting of a conduit that returns the refrigerant that has passed through the container to supercool the refrigerant on the first refrigeration circuit side to the inlet side of the compressor; and a cooling device characterized by comprising: . 2. The cooling device according to claim 1, wherein the condenser of the second refrigeration circuit is arranged upstream of the ventilation with respect to the condenser of the first refrigeration circuit.