JPH04316962A - Refrigeration cycle - Google Patents

Abstract

PURPOSE:To improve cooling capacity by a method wherein dryness at the outlet part of a refrigerant vaporizer is controlled to an optimum value. CONSTITUTION:The opening time of a first flow rate regulating valve 4 is controlled so that dryness of a refrigerant detected by a dryness sensor 14 located in the vicinity of the outlet part of a refrigerant vaporizer 6 is adjusted to, for example, 0.8-0,9. Through regulation of an amount of a refrigerant in an accumulator 7 sucked from the suction part of an ejector 5, an amount of a liquid refrigerant flowing in the refrigerant vaporizer 6 is increased. This constitution enables suppression of lowering of transmissibility on the refrigerant side at the outlet part of the refrigerant vaporizer 6 during operation of a freezing cycle 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle.

0002

2. Description of the Related Art FIG. 8 is a diagram showing a conventional refrigeration cycle. Conventionally, the refrigeration cycle 100 includes a refrigerant compressor 1
01, a refrigerant condenser 102, an ejector 103, a first refrigerant evaporator 104, and an accumulator 105 are connected in an annular manner by a refrigerant pipe 106. Further, the liquid refrigerant separated by the accumulator 105 passes through a bypass pipe 109 provided with a pressure reducing device 107 and a second refrigerant evaporator 108, and is sucked into the suction section of the ejector 103.

0003

However, in the conventional refrigeration cycle 100, the first and second refrigerant evaporators 10
4. Since the dryness of the refrigerant at the outlet of 108 is not controlled to an optimal value, the amount of heat exchanged in the refrigerant evaporator changes due to changes in heat load and operating conditions (especially the rotational speed of the refrigerant compressor). As a result, the dryness of the refrigerant at the outlet of the refrigerant evaporator changes, so it cannot be used in a range where the refrigerant side heat transfer coefficient is high. As a result, the first and second refrigerant evaporators 104,
There was a problem in that the refrigerant evaporation capacity of the refrigeration cycle 108 was reduced and the cooling capacity of the refrigeration cycle 100 was reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a refrigeration cycle that improves cooling capacity by controlling the degree of dryness at the outlet of a refrigerant evaporator to an optimum value.

[0005]

[Means for Solving the Problems] The present invention provides a refrigerant evaporator that evaporates refrigerant that flows in from an inlet, and an accumulator that separates refrigerant that flows out from an outlet of the refrigerant evaporator into liquid refrigerant and refrigerant gas. , a bypass pipe that communicates the inside of the accumulator with the inlet of the refrigerant evaporator;
refrigerant feeding means having an adjusting means for adjusting the flow rate of the liquid refrigerant flowing in the bypass pipe, and sending the liquid refrigerant in the accumulator to the inlet of the refrigerant evaporator via the bypass pipe; A technical means is adopted that includes a detection means for detecting the degree of dryness of the refrigerant at the outlet, and a control means for controlling the adjustment means according to the degree of dryness of the refrigerant detected by the detection means.

[0006]

[Operation] The present invention controls the amount of liquid refrigerant separated in the accumulator to the inlet of the refrigerant evaporator by controlling the adjusting means according to the dryness of the refrigerant at the outlet of the refrigerant evaporator. The value is adjusted according to the degree of dryness. Therefore, the amount of refrigerant circulated through the refrigerant evaporator increases in accordance with the degree of dryness of the refrigerant, thereby suppressing a decrease in the refrigerant-side heat transfer coefficient at the outlet of the refrigerant evaporator during operation of the refrigeration cycle. As a result, a decrease in refrigerant evaporation capacity at the outlet of the refrigerant evaporator is suppressed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The refrigeration cycle of the present invention will be explained based on the embodiments shown in FIGS. 1 to 7. 1 to 4 are diagrams showing a first embodiment of the present invention, and FIG. 1 is a diagram showing a refrigeration cycle.

The refrigeration cycle 1 is an accumulator cycle, and includes a refrigerant compressor 2, a refrigerant condenser 3, a first flow rate regulating valve 4, an ejector 5, a refrigerant evaporator 6, an accumulator 7, and these are connected so that the refrigerant circulates. A refrigerant pipe 8 is provided. Further, a bypass pipe 10 with a second flow rate regulating valve 9 interposed therebetween is connected between the bottom of the accumulator 7 and the suction part of the ejector 5.

The refrigerant compressor 2 is rotationally driven by an internal combustion engine or an electric motor (neither of which is shown), compresses the refrigerant gas drawn into the interior from the accumulator 7, and transfers the high-temperature and high-pressure refrigerant gas to the refrigerant condenser 3. Discharge toward.

[0010] The refrigerant condenser 3 condenses the refrigerant gas flowing into the interior from the refrigerant compressor 2 by exchanging heat with air passing outside. The first flow rate regulating valve 4 is the regulating means of the present invention, and opens when energized and closes when energized. The first flow rate regulating valve 4 adjusts the flow rate of refrigerant flowing into the ejector 5 according to the valve opening time, thereby controlling the flow rate of liquid refrigerant drawn into the suction section of the ejector 5 from the bypass pipe 10. .

The ejector 5 is composed of a nozzle 11 and a diffuser 12, and sucks the liquid refrigerant in the accumulator 7 from a suction section through a bypass pipe 10. The diffuser 12 boosts the pressure of the refrigerant passing therethrough. In this embodiment, the first flow rate regulating valve 4 and the ejector 5 constitute the refrigerant feeding means of the present invention.

The refrigerant evaporator 6 evaporates the atomized refrigerant that flows in from the inlet by exchanging heat with air passing outside. Then, the refrigerant evaporator 6 causes the refrigerant that has evaporated to become a gas-liquid mixed refrigerant to flow out from the outlet portion.

The accumulator 7 separates refrigerant gas and liquid refrigerant, sends only the refrigerant gas to the refrigerant compressor 2, and temporarily stores the liquid refrigerant at the bottom. Further, the liquid refrigerant in the accumulator 7 passes through the bypass pipe 10 and the ejector 5 and returns to the inlet of the refrigerant evaporator 6.

The second flow rate regulating valve 9 opens when energized and closes when the energization is stopped, allowing the liquid refrigerant in the accumulator 7 to flow through the inlet of the refrigerant evaporator 6 through the bypass pipe 10. Supply and stop supply to.

Further, the opening time of the first flow rate regulating valve 4 is controlled by the computer 13. computer 13
is a control means of the present invention, which detects the dryness of the refrigerant at the outlet of the refrigerant evaporator 6 detected by a dryness sensor (void sensor) 14 as a detection means provided near the outlet of the refrigerant evaporator 6. The degree is an optimal value (for example, 0.8 to 0.
9) The opening time of the first flow rate regulating valve 4 is controlled to adjust the amount of liquid refrigerant returned from the accumulator 7 to the inlet of the refrigerant evaporator 6.

Furthermore, when the amount of liquid refrigerant detected by the float sensor 15 provided in the accumulator 7 drops below a set amount, the computer 13 stops energizing the second flow rate regulating valve 9 to close the valve. let

The operation of this refrigeration cycle 1 will be explained based on FIGS. 1 to 4. Here, FIG. 2 shows the state points of the refrigerant in the refrigeration cycle 1 in FIG. 1 drawn on a Mollier diagram, and the states of the refrigerants a to e in the refrigeration cycle 1 in FIG. Corresponds to a to e.

The refrigerant gas compressed by the refrigerant compressor 2 to a high temperature and high pressure (state point b) is condensed and liquefied in the refrigerant condenser 3 (state point c), and then passes through the first flow rate regulating valve 4. It flows into the ejector 5. The liquid refrigerant that has flowed into the ejector 5 is depressurized when passing through the nozzle 11, and is at a state point d2.
Then, when passing through the diffuser 12, the pressure is increased to reach state point d.

At this time, when the liquid refrigerant passes through the nozzle 11, by utilizing the pressure drop around the refrigerant flowing out from the nozzle 11 at high speed, the liquid at the state point d1 flowing into the suction section of the ejector 5 from the bypass pipe 10 Refrigerant is aspirated. Therefore, the liquid refrigerant coming from the refrigerant condenser 3 and the accumulator 7
and the liquid refrigerant coming from the ejector 5. Therefore, the refrigerant flowing out from the ejector 5 reaches state points d1 and d
2 and the refrigerant flow rate from the refrigerant condenser 3 and the bypass pipe 1
The state point d is determined by the refrigerant flow rate from 0.

Note that the refrigerant flow rate from the refrigerant condenser 3 is set to a value that is optimal for the dryness of the refrigerant at the outlet of the refrigerant evaporator 6 detected by the dryness sensor 14 (for example, 0.8 to 0.0.
9) by controlling the opening time of the first flow rate regulating valve 4. The amount of suction at the suction section of the ejector 5 also changes depending on the flow rate of refrigerant from the refrigerant condenser 3. Therefore, the flow rate of liquid refrigerant sucked from the bypass pipe 10 to the suction section of the ejector 5 also decreases
This corresponds to the degree of dryness of the refrigerant at the outlet.

The refrigerant that has flowed into the refrigerant evaporator 6 is evaporated so that 10% to 20% of the refrigerant mass flow rate is present in the vicinity of the outlet (state point e), and then the refrigerant is transferred to the accumulator 7. The refrigerant gas and liquid refrigerant are separated into the refrigerant gas and liquid refrigerant. After that, the refrigerant gas in the accumulator 7 (state point a)
is sucked into the refrigerant compressor 2 by the suction force of the refrigerant compressor 2. Furthermore, the liquid refrigerant at the state point d1 accumulated at the bottom of the accumulator 7 is sucked into the suction section through the bypass pipe 10 by the suction effect of the ejector 5.

Note that when the amount of liquid refrigerant detected by the float sensor 15 is less than the set amount, for example, when the amount of liquid refrigerant at the bottom of the accumulator 7 is insufficient, the computer 13 stops energizing the second flow rate regulating valve 9. bypass pipe 1
0 is closed. Therefore, refrigerant gas can be prevented from being sucked into the suction section of the ejector 5.

As described above, by employing the refrigeration cycle 1 of this embodiment, liquid refrigerant always flows into the refrigerant evaporator 6 in an amount increased by 10% to 20% of the refrigerant circulation amount, and
As the flow rate of the refrigerant flowing through the refrigerant evaporator 6 is higher than that of the conventional technology, as shown in the graph of FIG. Therefore, the refrigerant evaporation performance of the refrigerant evaporator 6 can be improved. The graph of FIG. 3 shows the range of use of the present invention and the range of use of the prior art from the inlet to the outlet of the refrigerant evaporator 6.

Next, the graph in FIG. 4 shows the cooling capacity ratio to the dryness x of each refrigerant, assuming that the cooling capacity when the dryness x of the refrigerant at the outlet of the refrigerant evaporator 6 is 1.0 is 100. represents. As can be seen from the graph of FIG. 4, by setting the refrigerant dryness x at the outlet of the refrigerant evaporator 6 to 0.8 to 0.9, the Approximately 11% to 13% compared to cooling capacity
% improvement in cooling capacity can be expected.

FIG. 5 is a diagram showing a refrigeration cycle according to a second embodiment of the present invention. In this embodiment, a computer 13 controls the pumping force of a refrigerant pump 16 as an adjusting means and a refrigerant feeding means in accordance with a detected value of a dryness sensor 14, and liquid is returned from an accumulator 7 to an inlet of a refrigerant evaporator 6. By adjusting the amount of refrigerant, the degree of dryness of the refrigerant at the outlet of the refrigerant evaporator 6 can be adjusted to an optimal value (for example, 0).
．． 8 to 0.9).

FIG. 6 is a diagram showing a refrigeration cycle according to a third embodiment of the present invention. In this embodiment, a pressure reducing device 17 and a refrigerant evaporator 18 are arranged in a bypass pipe 10, and a dryness sensor 19 is provided near the outlet of the refrigerant evaporator 18. The detection value detected by this dryness sensor 19 is sent to the computer 20. This computer 20 controls the opening time of the second flow rate regulating valve 21 according to the detected value of the dryness sensor 19. Therefore, the amount of liquid refrigerant flowing into the inlet of the refrigerant evaporator 18 is adjusted so that the degree of dryness of the refrigerant at the outlet of the refrigerant evaporator 18 is an optimal value (for example, 0.8 to 0.9). .

The operation of this refrigeration cycle 1 will be explained based on FIGS. 6 and 7. Here, FIG. 7 shows the state points of the refrigerant in the refrigeration cycle 1 in FIG. 6 on the Mollier diagram, and the states of the refrigerants a to g in the refrigeration cycle 1 in FIG. 6 are on the Mollier diagram in FIG. Corresponds to a to g.

In this embodiment, the liquid refrigerant flowing into the ejector 5 is depressurized by the diffuser 12 to a low pressure Ps, and the liquid refrigerant coming from the refrigerant condenser 3 reaches a state point d2. At this time, from the suction part of the ejector 5 to the refrigerant evaporator 1
Since the refrigerant at the state point d1 flowing out from the refrigerant 8 is sucked, the state point d is determined by the state points d1, d2, the refrigerant flow rate from the refrigerant condenser 3, and the refrigerant flow rate from the refrigerant evaporator 18.

Thereafter, the refrigerant (state point e) flowing out from the outlet of the refrigerant evaporator 6 is separated into liquid refrigerant at state point f and refrigerant gas at state point a in the accumulator 7. The liquid refrigerant flowing through the bypass pipe 10 at the state point f due to the suction effect of the ejector 5 is depressurized through the pressure reducing device 17, becomes the state point g, and flows into the refrigerant evaporator 18.

The refrigerant flowing into the refrigerant evaporator 18 evaporates at a pressure Ps1 lower than the suction pressure Ps of the refrigerant evaporator 6 or the refrigerant compressor 2, and becomes a saturated gas at a state point d1.
It is sucked into the ejector 5. Note that the amount of liquid refrigerant flowing into the refrigerant evaporator 18 is controlled by the second flow rate regulating valve 21 so that the degree of dryness of the refrigerant at the outlet of the refrigerant evaporator 18 is 0.8 to 0.9. Therefore, 1 during the mass flow rate
The gas-liquid mixed refrigerant containing 20% to 20% liquid refrigerant is ejected to the ejector 5.
It is sucked into the suction part of.

In the Mollier diagram of FIG. 7, a solid line Y indicates the prior art in which the first and second flow rate regulating valves 4 and 21 and the dryness sensors 14 and 19 are not provided. As shown in the Mollier diagram of FIG. 7, it can be seen that the refrigeration cycle 1 of this embodiment has improved cooling capacity compared to the conventional technology. In addition, in the refrigeration cycle 1 of this embodiment, the evaporation pressure of the refrigerant evaporator 18 can be set lower than the evaporation pressure of the refrigerant evaporator 6, so that the temperature between the air passing outside the refrigerant evaporator 18 and the refrigerant flowing inside the refrigerant evaporator 18 is lower than that of the refrigerant evaporator 6. The difference can be made large, and the cooling capacity can be further improved compared to the first embodiment.

(Modification) In this embodiment, the flow rate of the liquid refrigerant returned to the inlet of the refrigerant evaporator was adjusted by controlling the length of the opening time of the flow rate adjustment valve. The adjustment may be made by controlling the size of the opening diameter of the proportional control valve. In this embodiment, the degree of dryness x at the outlet of the refrigerant evaporator is set to 0.8 to 0.9, but it may be freely changed as long as it is within the range of 0.7<x<1.0.

[0033]

According to the present invention, since a decrease in the refrigerant evaporation capacity at the outlet of the refrigerant evaporator is suppressed, a decrease in the cooling capacity of the refrigeration cycle can be prevented, and stable cooling operation can be performed for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit diagram showing a refrigeration cycle of a first embodiment.

FIG. 2 is a Mollier diagram of the refrigeration cycle of the first embodiment.

FIG. 3 is a graph showing the relationship between the refrigerant side heat transfer coefficient and the dryness of the refrigerant at the outlet of the refrigerant evaporator.

FIG. 4 is a graph showing the relationship between the cooling capacity of the refrigeration cycle and the dryness of the refrigerant from the inlet to the outlet of the refrigerant evaporator.

FIG. 5 is a refrigerant circuit diagram showing a refrigeration cycle of a second embodiment.

FIG. 6 is a refrigerant circuit diagram showing a refrigeration cycle of a third embodiment.

FIG. 7 is a Mollier diagram of the refrigeration cycle of the third embodiment.

FIG. 8 is a refrigerant circuit diagram of a conventional refrigeration cycle.

[Explanation of symbols]

1 Refrigeration cycle 4 First flow rate adjustment valve (adjustment means) 5 Ejector (refrigerant feeding means) 6 Refrigerant evaporator 7 Accumulator 13 Computer (controlling means) 14 Dryness sensor (detection means) 16 Refrigerant pump (adjustment means, refrigerant feeding means) )19
Dryness sensor (detection means) 20 Computer (control means) 21 Second flow rate adjustment valve (adjustment means)

Claims (1)

[Claims] Claim 1: (a) a refrigerant evaporator that evaporates refrigerant flowing in from an inlet; (b) an accumulator that separates refrigerant flowing out from an outlet of the refrigerant evaporator into liquid refrigerant and refrigerant gas; c) a bypass pipe that communicates the inside of the accumulator with the inlet of the refrigerant evaporator;
) a refrigerant sending means having an adjusting means for adjusting the flow rate of the liquid refrigerant flowing through the bypass pipe, and sending the liquid refrigerant in the accumulator to the inlet of the refrigerant evaporator via the bypass pipe; A refrigeration cycle comprising: a detection means for detecting the degree of dryness of the refrigerant at an outlet of a refrigerant evaporator; and a control means for controlling the adjustment means according to the degree of dryness of the refrigerant detected by the detection means.