Patent Application
20220186999
The present invention relates to a refrigerant condition detection device, a refrigerant condition detection method, and a temperature control system.
When a refrigeration circuit leaks a refrigerant to run short of the refrigerant, a refrigeration capacity may lower and/or another problem may occur, for example. Thus, some measures should be taken as soon as possible.
Various technologies for detecting a refrigerant leakage have been proposed in the past. For example, JP2016-121867A discloses a technique for detecting a refrigerant leakage by detecting a compressor intake pressure, an evaporator pressure, a compressor discharge pressure, a condenser pressure, a compressor intake temperature, an evaporator outlet temperature, a compressor discharge temperature, a condenser inlet temperature and so on, and using these detected values as parameters. In addition, WO2017/175300 discloses a technique of providing an indoor unit of an air conditioner with a refrigerant detection device that detects a refrigerant having leaked outside.
However, the technique of JP2016-121867A requires many sensors for detecting pressures, temperature, etc., and a lot of parameters are used to determine a refrigerant leakage. In addition, the technique of WO2017/175300 directly detects a refrigerant that has leaked outside by the refrigerant detection device. Thus, it is difficult to detect the leaked refrigerant at a distance from the refrigerant detection device, and it is difficult to accurately detect a refrigerant shortage.
In consideration of the aforementioned known technique, the present inventor conducted intensive research to detect a refrigerant leakage or a refrigerant shortage very simply and accurately. The present inventor then found that, when a refrigerant shortage occurs, an outlet temperature of a condenser becomes higher than the outlet temperature of the condenser which does not run short of the refrigerant. The present inventor also found that this phenomenon is caused by the fact that under the refrigerant shortage, an amount of the refrigerant condensed in the condenser is less than a planned or expected amount of condensation, so that a high-temperature refrigerant still in a gaseous state tends to flow out from a condenser outlet into a downstream pipe.
The present invention has been made in view of the above findings. The object of the present invention is to provide a refrigerant condition detection device, a refrigerant condition detection method, and a temperature control system, which are capable of simply and accurately detecting a leakage or shortage of a refrigerant in a refrigerant circuit.
A refrigerant condition detection device according toe the present invention comprises:
a temperature information acquisition unit that acquires a temperature of a refrigerant flowing out from a condenser of a refrigeration circuit having a compressor, the condenser, an expansion valve, and an evaporator, and also acquires a temperature of a cooling fluid before it cools the refrigerant in the condenser; and
a refrigerant condition determination unit that determines that a leakage or shortage of the refrigerant occurs, when a difference between the temperature of the refrigerant and the temperature of the cooing fluid, which are acquired by the temperature information acquisition unit, exceeds a threshold value previously recorded.
The condenser may be a liquid-cooled heat exchanger, and the cooing fluid may be a liquid.
The condenser may have a first condensing part and a second condensing part that condenses the refrigerant flowing out from the first condensing part; and
the temperature information acquisition unit may acquire a temperature of the refrigerant flowing out from the second condensing part, and a temperature of the cooling fluid before it cools the refrigerant in the second condensing part.
A refrigerant condition detection method according to the present invention comprises:
a temperature information acquisition step that acquires a temperature of a refrigerant flowing out from a condenser of a refrigeration circuit having a compressor, the condenser, an expansion valve, and an evaporator, and also acquires a temperature of a cooling fluid before it cools the refrigerant in the condenser; and
a refrigerant condition determination step that determines that a leakage or shortage of the refrigerant occurs when a difference between the temperature of the refrigerant and the temperature of the cooling fluid, which are acquired in the temperature information acquisition step, exceeds a threshold value previously recorded.
The refrigerant condition detection method according to the present invention may further comprise a filling step that fills the refrigeration circuit with a predetermined amount of the refrigerant that enables an operation of the refrigeration circuit by which a difference between an acquired temperature of the refrigerant flowing out from the condenser and an acquired temperature of the cooling fluid before it cools the refrigerant in the condenser becomes the threshold value or below,
wherein a leakage or shortage of the refrigerant may be determined by the temperature information acquisition step and the refrigerant condition determination step that are performed after the filling step.
During the operation of the refrigeration circuit after the filling step, the refrigeration circuit may cool the refrigerant in the condenser such that the refrigerant condensed by the condenser covers an outlet of the condenser.
A temperature control system according to the present invention comprises:
a refrigeration circuit having a compressor, a condenser, an expansion valve, and an evaporator; and
the aforementioned refrigeration condition detection device.
When the refrigeration circuit is filled with a predetermined amount of the refrigerant, the refrigeration circuit may be capable of performing an operation by which a difference between a temperature of the refrigerant and a temperature of the cooling fluid, which are acquired by the refrigerant condition detection device, becomes the threshold value or below.
When the refrigeration circuit is filled with the predetermined amount of the refrigerant, the refrigeration circuit may be capable of cooling the refrigerant in the condenser such that the refrigerant condensed by the condenser covers the outlet of the condenser.
The temperature control system according to the present invention may further comprise a fluid flow device that causes a fluid whose temperature is controlled by the evaporator to flow.
The present invention can simply and accurately a leakage or shortage of a refrigerant in a refrigeration circuit.
Respective embodiments of the present invention are described herebelow.
The refrigeration circuit 10 has a compressor 11, a condenser 12, a receiver tank 13, an expansion valve 14, and an evaporator 15. The compressor 11, the condenser 12, the receiver tank 13, the expansion valve 14, and the evaporator 15 are connected by pipe members such that a refrigerant is circulated in this order.
The compressor 11 compresses a low-temperature and low-pressure gaseous refrigerant flowing out from the evaporator into the high-temperature and high-pressure gaseous refrigerant, and supplies it to the condenser 12. The condenser 12 cools, by means of a cooling fluid, the refrigerant compressed by the compressor 11 to condense it to the high-pressure liquid refrigerant having a predetermined cooling temperature.
In this embodiment, the condenser 12 has a first condensing part 121, and a second condensing part 122 that condenses the refrigerant flowing out from the first condensing part 121. The refrigerant passing through the first condensing part 121 is cooled by a first cooling fluid which is supplied by the first cooing fluid flow device 21 to the first condensing part 121. The refrigerant passing through the second condensing part 122 is cooled by a second cooling fluid which is supplied by the second fluid flow device 22 to the second condensing part 122.
Each of the first condensing part 121 and the second condensing part 122 is formed by a liquid-cooled heat exchanger, specifically, a plate-type heat exchanger. However, the first condensing part 121 and the second condensing part 122 may be air-cooled heat exchangers.
The receiver tank 13 receives the refrigerant, which has been condensed by the condenser 12 to the liquid refrigerant, and stores it therein. The refrigerant stored in the receiver tank 13 flows toward the expansion valve 14. The expansion valve 14 expands to decompress the refrigerant supplied from the receiver tank 13 into the low-temperature and low-pressure refrigerant in a liquid state or gas-liquid mixed state, and supplies it to the evaporator 15. In this embodiment, the evaporator 15 heat-exchanges between the refrigerant, which has been supplied thereto, and a temperature control target fluid, which is caused to flow by the temperature control target fluid flow device 30. The refrigerant having been heat-exchanged with the temperature control target fluid becomes again the low-temperature and low-pressure gaseous refrigerant. The refrigerant flows out from the evaporator 15 and is again compressed by the compressor 11.
The first cooling fluid flow device 21 supplies the first condensing part 121 with the first cooing fluid, and the second cooling fluid flow device 22 supplies the second condensing part 122 with the second cooling fluid. As described above, since the first condensing part 121 and the second condensing part 122 are formed by liquid-cooled heat exchangers in this embodiment, liquids are used as the first cooling fluid and the second cooling fluid.
The first cooling fluid and the second cooling fluid, which are liquids, may be water or another fluid. When the first condensing part 121 and the second condensing part 122 are formed by air-cooled heat exchangers, the first cooling fluid and the second cooling fluid may be air.
In this embodiment, the second cooling fluid flow device 22 has a pump 22A. By controlling a driving force of the pump 22A, a flow rate of the second cooling fluid to be supplied to the second condensing part 122 can be regulated. Thus, a cooling capacity of the refrigerant in the second condensing part 122 can be regulated.
As described above, the temperature control target fluid flow device 30 causes the temperature control target fluid, which heat-exchanges with the refrigerant in the evaporator 15, to flow. The temperature control target fluid caused to flow by the temperature control target fluid flow device 30 may be either a gas or a liquid.
When the temperature control target fluid is a gas, the temperature control target fluid flow device 30 may be formed by a fan or the like. On the other hand, when the temperature control target fluid is a liquid, the temperature control target fluid flow device 30 may be formed by a liquid flow path, a pump for causing a liquid to flow, etc.
The refrigeration circuit 10 is provided with a refrigerant temperature sensor 16 that detects a temperature of the refrigerant flowing out from the second condensing part 122, and a refrigerant pressure sensor 17 that detects a pressure of the refrigerant flowing out from the second condensing part 122. Specifically, the refrigerant temperature sensor 16 detects a temperature of the refrigerant that has flown out from the second condensing part 122 but does not yet flow into the receiver tank 13. In other words, the refrigerant temperature sensor 16 detects a temperature inside a pipe member connected to an outlet of the second condensing part 122. The refrigerant pressure sensor 17 detects the pressure of a refrigerant that has flown out from the second condensing part 122 but does not yet flow into the receiver tank 13. In other words, the refrigerant pressure sensor 17 detects a pressure inside the pipe member connected to the outlet of the second condensing part 122.
The second cooling fluid flow device 22 is provided with a cooing fluid temperature sensor 22B. The cooling fluid flow device 22B detects a temperature of the second cooling fluid temperature before it cools the refrigerant in the second condensing part 122. In other words, the cooling fluid temperature sensor 22B detects a temperature inside a part of a pipe member, the part being upstream of the second condensing part 122. The second cooling fluid flow device 22 causes the second cooling fluid to flow through the pipe.
The controller 40 can control operations of the respective units of the refrigeration circuit 10, the pump 22A of the second cooling fluid flow device 22 and the like, and can acquire information from the aforementioned respective sensors 16, 17 and 22B. The controller 40 may comprise, for example, a computer equipped with a CPU, a ROM, a RAM, etc. to control operations of the aforementioned respective units in accordance with a stored program.
The controller 40 has a temperature information acquisition unit 41, a refrigerant condition determination unit 42, an operation control unit 43, and an output unit 44.
The temperature information acquisition unit 41 acquires, from the refrigerant temperature sensor 16, a temperature of the refrigerant flowing out from the second condensing part 122 of the condenser 12, and acquires, from the cooling fluid temperature sensor 22B, a temperature of the second cooling fluid temperature before it cools the refrigerant in the second condensing part 122.
The refrigerant condition determination unit 42 determines that a leakage or shortage of the refrigerant occurs, when a difference between the temperature of the refrigerant and the temperature of the second cooling fluid, which are acquired by the temperature information acquisition unit 41, exceeds a previously recorded threshold value. Herein, the temperature information acquisition unit 41 and the refrigerant condition judgment unit 42 constitute a refrigerant condition detection device 40A.
The operation control unit 43 controls operations of the respective units of the refrigeration circuit 10, the pump 22A of the second cooling fluid flow device 22 and the like.
The output unit 44 displays a warning on a display device, not shown, when the refrigerant condition determination unit 42 determines that a leakage or shortage of the refrigerant occurs.
Herebelow, a determination flow of a leakage or shortage of the refrigerant by the refrigerant condition detection device 40A in this embodiment is described.
A structure of the second condensing part 122, and an inside condition of the second condensing part 122 during operation of the refrigeration circuit 10 are described first.
A refrigerant inlet 122D and a refrigerant outlet 122E are connected to a plate member 122A which is positioned on one end of the stacking direction of the plate members 122A. As shown by a white arrow, the refrigerant flows from the refrigerant inlet 122D to the second cooling fluid flow path 122B, and flows out from the refrigerant outlet 122E. The refrigerant inlet 122D and the refrigerant outlet 122E are disposed distant from each other in a direction orthogonal to the stacking direction. In this embodiment, the second condensing part 122 is arranged such that the refrigerant inlet 122D is positioned above the refrigerant outlet 122E in an up and down direction. The refrigerant inlet 122D may be a part of a pipe member connecting the first condensing part 121 and the second condensing part 122, or a member separated from the pipe member. Similarly, the refrigerant outlet 122E may be a part of a pipe member connecting the second condensing part 122 and the receiver tank 13, or may be a member separated from the pipe member.
On the other hand, although not shown, a second cooling fluid inlet and a second cooling fluid outlet are connected to a plate member 122A which is positioned on one end of the stacking direction. As shown by a hatched arrow, the second cooling fluid flows from the second cooling fluid inlet to the second cooling fluid flow path 122C, and flows out from the second cooling fluid outlet.
The second cooling fluid inlet and the second cooling fluid outlet are disposed distant from each other in the direction orthogonal to the stacking direction. The second cooling fluid inlet is provided on the same side as the refrigerant outlet 122E in the direction orthogonal to the stacking direction, and the second cooling fluid outlet is provided on the same side as the refrigerant inlet 122D in the direction orthogonal to the stacking direction. Thus, in this embodiment, the second cooling fluid outlet is positioned above the second cooling fluid inlet in the up and down direction. However, the second cooling fluid inlet may be provided on the same side as the refrigerant inlet 122D in the direction orthogonal to the stacking direction, and the cooling fluid outlet may be provided on the same side as the refrigerant outlet 122E in the direction orthogonal to the stacking direction.
A symbol LM shown in
In this embodiment, in order that the liquid refrigerant LM covers the refrigerant outlet 122E, the operation control unit 43 of the controller 40 controls the pump 22A of the second cooling fluid flow device 22 depending on a refrigerant pressure value from the refrigerant pressure sensor 17.
Specifically, when a cooling capacity of the second cooling fluid flow device 22 is low so that the refrigerant is not sufficiently condensed, the liquid level height of the refrigerant LM accumulated at the bottom of the second condensing part 122 may not exceed the upper end of the refrigerant outlet 122E and the refrigerant in a gaseous state may enter the refrigerant outlet 122E. At this time, a pressure value of the refrigerant, which is detected by the refrigerant pressure sensor 17, becomes larger than a case in which the refrigerant outlet 122E is filled with the liquid refrigerant. Thus, a condition in which the liquid refrigerant LM covers the refrigerant outlet 122E can be formed by firstly determining as a threshold value a pressure value detected by the refrigerant pressure sensor 17 when the refrigerant outlet 122E is filled with the liquid refrigerant, and by controlling the pump 22A of the second cooling fluid flow device 22 depending on a pressure value of the refrigerant from the refrigerant pressure sensor 17.
As described above, when the liquid refrigerant LM covers the refrigerant outlet 122E, a difference between a temperature of the refrigerant, which is detected by the refrigerant temperature sensor 16, and a temperature of the second cooling fluid, which is detected by the cooling fluid temperature sensor 22B before the second cooling fluid cools the refrigerant, is small. Ideally, the temperatures are the same. When a difference between a temperature of the refrigerant detected by the refrigerant temperature sensor 16 and a temperature of the second cooling fluid detected by the cooling fluid temperature sensor 22B is small, it can be said that a normal operation by which the liquid refrigerant LM covers the refrigerant outlet 122E is performed, and that the refrigeration circuit 10 is filled with a proper predetermined amount of the refrigerant. Such a predetermined amount of the refrigerant can be determined through calculation or verification, taking into consideration the size of the refrigeration circuit 10 and the refrigeration capacity required therefor.
On the other hand, although the cooling capacity of the second cooling fluid flow device 22 is controlled such that the liquid refrigerant LM covers the refrigerant outlet 122E, as described above, there is a possibility that the liquid level height of the refrigerant LM accumulated on the bottom of the second condensing part 122 does not exceed the upper end of the refrigerant outlet 122E, as shown in
The present inventor has found that, when a leakage or shortage of the refrigerant occurs in the refrigerant circuit 10, a difference between a temperature of the refrigerant, which is detected by the refrigerant temperature sensor 16, and a temperature of the second cooling fluid, which is detected by the cooling fluid temperature sensor 22B, becomes large. Thus, the present inventor came to adopt the refrigerant condition detection device 40A which determines that a leakage or shortage of the refrigerant occurs, when a difference therebetween exceeds a previously recorded threshold value.
The present inventor has found that a threshold value for determining a leakage or shortage of a refrigerant is preferably 2° C. or higher, more preferably between 2° C. or higher and 6° C. or lower, and further preferably between 2° C. or higher and 4° C. or lower. A threshold value set in such a range improves determination accuracy of a leakage or shortage of a refrigerant.
In the determination of a leakage or shortage of the refrigerant, a moving average value of a difference between a temperature of the refrigerant detected by the refrigerant temperature sensor 16 and a temperature of the second cooling fluid detected by the cooling fluid temperature sensor 22B may be calculated, and this moving average value may be compared with the aforementioned threshold value. The moving average value may be calculated using a difference between a temperature of the refrigerant detected by the refrigerant temperature sensor 16 and a temperature of the second cooling fluid detected by the cooling fluid temperature sensor 22B at three or more detection points in a detection period of three seconds or more. The use of the moving average value can improve determination accuracy by suppressing influence of noise in the sensors.
As described above, in this embodiment, the refrigerant circuit 10 is provided with the refrigerant condition detection device 40A. The refrigerant condition detection device 40A comprises the temperature information acquisition unit 41 that acquires a temperature of the refrigerant flowing out from the second condensing part 122 and acquires a temperature of the second cooling fluid temperature before it cools the refrigerant in the second condensing part 122, and the refrigerant condition determination unit 42 that determines that a leakage or shortage of a refrigerant occurs when a difference between the temperature of the refrigerant and the temperature of the second cooling fluid, which are acquired by the temperature information acquisition unit 41, exceeds a threshold value previously recorded.
Such a refrigerant condition detection device 40A uses the lesser number of parameters for determination of a leakage or shortage of the refrigerant. In addition, the use of a temperature as a determination parameter can improve determination accuracy of a leakage or shortage of the refrigerant. Namely, in a case where a temperature of the refrigerant in the refrigeration circuit 10 is detected, sudden fluctuation and/or noise detection can be suppressed as compared with a case in which a pressure is detected.
Thus, this embodiment enables simple and accurate detection of a leakage or shortage of a refrigerant in the refrigeration circuit 10.
Next, a temperature control system 2 according to a second embodiment is described with reference to
As shown in
In a refrigerant condition detection device 40A, a temperature information acquisition unit 41 acquires, from a refrigerant temperature sensor 16, a temperature of the refrigerant flowing out from the condenser 12, and acquires, from the cooing fluid temperature sensor 22B, a temperature of the cooling fluid before it cools the refrigerant in the condenser 12. A refrigerant condition determination unit 42 determines that a leakage or shortage of the refrigerant occurs, when a difference between the refrigerant temperature and the cooling fluid temperature, which are acquired by the temperature information acquisition unit 41, exceeds a previously recorded threshold value.
This embodiment also enables very simple and accurate detection of a leakage or shortage of a refrigerant.
Next, a temperature control system 3 according to a third embodiment is described with reference to
In this embodiment, a condenser 12 is formed by a single air-cooled heat exchanger. The condenser 12 is supplied with a cooling fluid which is a gas caused to flow by an air-cooling device 24 driving its fan. The cooling fluid may be air. A cooling fluid temperature sensor 22B provided on the air-cooling device 24 detects a temperature of the cooling fluid supplied to the condenser 12.
In a refrigerant condition detection device 40A, a temperature information acquisition unit 41 acquires, from a refrigerant temperature sensor 16, a temperature of the refrigerant flowing out from the condenser 12, and acquires, from the cooling fluid temperature sensor 22B, a temperature of the gaseous cooling fluid before it cools the refrigerant in the condenser 12. A refrigerant condition determination unit 42 determines that a leakage or shortage of the refrigerant occurs, when a difference between the refrigerant temperature and the cooling fluid temperature, which are acquired by the temperature information acquisition unit 41, exceeds a previously recorded threshold value.
This embodiment also enables very simple and accurate detection of a leakage or shortage of a refrigerant.
Although the embodiments of the present invention have been described above, the present invention is not limited to the aforementioned embodiments and an be variously modified. For example, in the aforementioned respective embodiments, the refrigeration circuit 10 is provided with the receiver tank 13, but the refrigeration circuit 10 need not have the receiver tank 13.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-089951 | May 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/018223 | 4/30/2020 | WO | 00 |
