JP2000249435A - Freezing apparatus and refrigerant leak detection method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of detection of refrigerant leak in a freezing apparatus. SOLUTION: A generation section 21 and a reception section 22 are provided in an adjacent manner on a casing 11 of an indoor unit 10. The generation section 21 generates ultrasonic waves toward a floor, and the reception section 22 receives ultrasonic waves reflected on the floor. A leak detection section measures arrival time required front the generation section 21 to the reception section 22. Further, the leak detection section sets time the ultrasonic waves reach with no refrigerant leak from. the generation section 21 to the reception section 22, as a reference time. Once any refrigerant leak is caused, refrigerant concentration in the air is changed to change a sound velocity. Since the arrival time is hereby changed, the leak detection section judges to be refrigerant leak when a time difference between the reference time and the arrival time becomes a predetermined judgement time or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system in which a refrigerant circulates in a refrigerant circuit to perform a refrigeration cycle, and relates to a measure for detecting a refrigerant leak.

[0002]

2. Description of the Related Art A refrigeration system in which a refrigerant circulates in a refrigerant circuit to perform a refrigeration cycle is known, and is used as an air conditioner or refrigeration equipment. As a refrigerant for this type of refrigeration apparatus, a so-called Freon refrigerant such as HCFC and HFC, and a so-called natural refrigerant such as propane, ammonia and carbon dioxide are used.

When this kind of refrigerant leaks from the refrigerant circuit into the room, the following problem occurs. That is, in the case of a CFC refrigerant, carbon dioxide, or the like, the occupant may suffocate. In addition, ammonia may cause poisoning, and propane may cause a fire. And
Conventionally, the above-described problem has been avoided by detecting a refrigerant leak using a gas sensor such as an oxygen deficiency sensor that measures the oxygen concentration in the air.

[0004]

However, since the above-mentioned gas sensor utilizes adsorption or chemical change on the sensor surface, the performance of the gas sensor is deteriorated due to dirt in the air, and the gas sensor lacks long-term reliability. There was a problem. Further, when the conventional gas sensor is used, there is a problem that the detection sensitivity is lower than that of the HCFC refrigerant because the HFC refrigerant does not have chlorine atoms. And as a result,
There has been a problem that refrigerant leakage cannot be reliably detected over a long period of time.

[0005] The present invention has been made in view of the above, and an object of the present invention is to improve the reliability of refrigerant leak detection in a refrigeration system.

[0006]

SUMMARY OF THE INVENTION According to the present invention, refrigerant leakage is detected by utilizing the fact that the sound speed changes due to a change in the concentration of refrigerant in the air.

More specifically, a first solution of the present invention is directed to a refrigeration system in which a refrigerant circulates in a closed circuit refrigerant circuit. Detection means (2
0).

[0008] The second solution taken by the present invention is:
In the first solving means, the detecting means (20) comprises: a transmitting section (21) for transmitting a sound wave into room air;
1) a receiving unit (22) for receiving the sound wave transmitted by
The receiving unit (22) detects the arrival time required until the sound wave transmitted by the transmitting unit (21) is received by the receiving unit (22), and detects a change in the speed of sound based on the detected arrival time.

Further, a third solution taken by the present invention is:
In the second solution, the temperature detecting means for detecting the temperature of the indoor air is provided, and the detecting means (20) changes the sound speed based on both the detected arrival time and the temperature detected by the temperature detecting means. Is configured to be detected.

[0010] A fourth solution taken by the present invention is:
In the second or third solving means, the detecting means (20)
However, when the time difference between the detected arrival time and the predetermined reference time is equal to or greater than a predetermined determination value, it is determined that a refrigerant leak has occurred.

Further, a fifth solution taken by the present invention is:
In the second or third solution, the transmitting unit (21) and the receiving unit (22) are connected to the casing (1) of the indoor unit (10).
The transmitting unit (21) is configured to transmit a sound wave toward the receiving unit (22) while being provided in (1).

Further, a sixth solution taken by the present invention is:
In the second or third solution, the transmitting unit (21) and the receiving unit (22) are connected to the casing (1) of the indoor unit (10).
While provided in 1), the transmitting unit (21) transmits a sound wave toward the outside of the casing (11), and the receiving unit (22) receives the reflected sound wave.

[0013] A seventh solution taken by the present invention is:
In the sixth solving means, when the time difference between the detected arrival time and the predetermined reference time is equal to or more than a predetermined determination value, the detecting means (20) determines that the refrigerant is leaking, and the change rate of the arrival time is If the time difference is equal to or more than the predetermined value, the determination is not made that the refrigerant is leaking even if the time difference is equal to or more than the determination value.

An eighth solution taken by the present invention is:
In any one of the first to seventh solving means, the refrigerant is a slightly flammable substance.

[0015] A ninth solution taken by the present invention is:
In any one of the first to seventh solving means, the refrigerant is R32 or a mixed refrigerant containing R32.

According to a tenth aspect of the present invention, there is provided a refrigerating apparatus in which a refrigerant circulates in a closed circuit refrigerant circuit to perform a refrigerating cycle, while transmitting a sound wave into room air. Measure the arrival time required to receive the transmitted sound wave after that, and then detect the change in the refrigerant concentration in the indoor air based on the change in the measured arrival time,
This is a refrigerant leakage detection method for detecting refrigerant leakage into a room based on a detected change in refrigerant concentration.

-Operation- In the first solution, the refrigerant circulates in the refrigerant circuit of the refrigeration apparatus to perform a refrigeration cycle operation. Further, a heat pump cycle may be performed. At that time, refrigerant may leak from the refrigerant circuit. On the other hand, the detecting means (20) detects refrigerant leakage into the room.

When the refrigerant concentration in the air changes,
Accordingly, the speed of sound in the air changes. That is, the sound speed v
[m / s] is represented as v = (k · P / ρ) ^1/2 by respective values of the specific heat ratio k, the pressure P [Pa], and the density ρ [kg / m ³ ]. Therefore, when the concentration of the refrigerant in the air changes, the specific heat ratio k and the density ρ of the mixed gas of the air and the refrigerant change, and the sonic velocity v changes accordingly. Specifically, Table 1 shows the change in sound speed when the refrigerant is R22. In addition, under atmospheric pressure, the pressure P is considered to be constant. Then, utilizing this change in the speed of sound, the detecting means (20) detects refrigerant leakage.

[0019]

[Table 1]

In the second solving means, the detecting means (20) measures an arrival time until a sound wave transmitted from the transmitting section (21) travels in the room air and reaches the receiving section (22). . Here, if the sound wave travels at the same distance, the arrival time changes when the sound speed changes. For this reason, the detecting means detects a change in the speed of sound based on a change in the arrival time, thereby detecting a refrigerant leak.

In the third solving means, the detecting means (20) detects the refrigerant leakage in consideration of not only the arrival time but also the temperature of the indoor air detected by the temperature detecting means.
Here, when the temperature of the room air changes, the specific heat ratio k and the density ρ change, so that the sound speed v changes. Therefore, if the temperature of the indoor air changes to some extent, it may not be possible to determine whether the change in the sound speed is due to the change in the refrigerant concentration or the change in the temperature. On the other hand, in the present solution, the change in the sound speed due to the change in the refrigerant concentration is reliably detected in consideration of the change in the sound speed due to the temperature change.

In the fourth solution, the detecting means (20) determines that refrigerant leakage has occurred when the time difference between the arrival time and the reference time is equal to or greater than a predetermined determination value.
For example, it is conceivable to set the arrival time when the refrigerant concentration is zero as the reference time. It should be noted that whether the sound speed increases or decreases as the refrigerant concentration in the air increases depends on whether the refrigerant density is lower or higher than the air density.
For this reason, the detecting means (20) detects refrigerant leakage based on the difference between the arrival time and the reference time.

In the fifth solution, the transmitting section (21) and the receiving section (22) are provided in the casing (11) of the indoor unit (10). Then, the sound wave transmitted by the transmitting unit (21) travels in the room air and reaches the receiving unit (22). At this time, the transmitting unit (21) and the receiving unit (22) may be provided inside the casing (11) so that the sound wave can be transmitted through the air inside the casing (11). The (22) may be provided outside the casing (11) so that the sound wave propagates in the air outside the casing (11).

In the sixth solution, the transmitting section (21) and the receiving section (22) are provided in the casing (11) of the indoor unit (10). The sound wave transmitted by the transmitting unit (21) travels through the indoor air, hits a wall surface, a floor surface, or the like in the room, is reflected, and then travels again through the indoor air to reach the receiving unit (22).

Further, in the seventh solution means, similar to the fourth solution means, when the time difference between the arrival time and the reference time becomes equal to or greater than a predetermined judgment value, the detecting means (20) generates a refrigerant leak. It is determined that it is. On the other hand, if the temporal change rate of the arrival time is equal to or greater than the predetermined value, the detection means (20) does not determine that the refrigerant is leaking even if the arrival time is equal to or greater than the determination value.

For example, the sound wave reflected on the floor surface is received by the receiving unit (2
In the case where 2) is received, if an object placed or placed between the transmitting unit (21) and the receiving unit (22) and the floor is removed, the transmitting unit (21) If a person passes under the like, the arrival time changes, and there is a possibility that a refrigerant leak is erroneously detected. However, in such a case,
The arrival time changes rapidly. On the other hand, the change in the refrigerant concentration at the time of refrigerant leakage is not so sharp, and the arrival time also changes gradually. Therefore, the detection means (20) prevents erroneous detection by not determining that a refrigerant leak has occurred in a predetermined case.

In the eighth or ninth means,
Certain substances are used as refrigerants. R32 is a slightly flammable refrigerant.

In the tenth solution, the leak of the refrigerant is detected by measuring the arrival time by utilizing the fact that the sound speed changes with the change in the concentration of the refrigerant in the air as described above.

[0029]

Thus, according to the above-described means, it is possible to detect a refrigerant leak by detecting a change in the speed of sound. For this reason, it is possible to avoid the problem that the detection performance deteriorates with time as compared with the conventional method of detecting a refrigerant leak using a chemical change or the like. Therefore, it is possible to reliably detect the refrigerant leakage over a long period of time. This makes it possible to reliably prevent adverse effects such as suffocation and fire due to refrigerant leakage.

In particular, according to the third solution, it is possible to cancel the influence of the change in the temperature of the indoor air on the change in the sound speed, and to reliably detect the change in the sound speed caused by the change in the refrigerant concentration. .

Further, according to the seventh solution, erroneous detection of refrigerant leakage can be reliably prevented, and the reliability of refrigerant leakage detection can be improved.

According to the eighth or ninth means, a slightly flammable substance such as R32 can be used as the refrigerant. That is, leakage of the slightly flammable substance may cause a fire or the like. On the other hand, since the refrigerant leak can be reliably detected by the detection means (20), even if a refrigerant leak occurs, it can be reliably detected. Flammable materials can be used as refrigerants.

[0033]

Embodiment 1 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The refrigeration apparatus of this embodiment is an air conditioner having an indoor unit (10) and an outdoor unit. This air conditioner has a closed circuit refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator (14) are sequentially connected by piping.
And the indoor unit (10) includes an evaporator (14),
The refrigerant R32 circulates in the refrigerant circuit to perform a refrigeration cycle operation to cool the room. Note that a four-way switching valve may be provided in the refrigerant circuit so that the circulation direction of the refrigerant can be freely switched to perform heating by a heat pump operation. In this case, the evaporator (14) of the indoor unit (10) operates as a condenser.

As shown in FIG. 1, the indoor unit (1
The evaporator (1) is placed in a vertically long rectangular parallelepiped casing (11).
4), etc., are housed in a so-called floor-standing configuration. An outlet (12) is formed in the upper part of the front surface of the casing (11), and a suction port (13) is formed in the lower part. A heat exchanger, which is an evaporator (14), is arranged inside the suction port (13) to exchange heat between the sucked room air and the refrigerant in the refrigerant circuit. Although not shown, a fan is provided in the casing (11).

A transmitter (21) is provided in the casing (11) near the bottom plate of the casing (11), and a predetermined distance of the transmitter (21) is provided above the transmitter (21). And a receiving section (22). The arrangement of the transmitting part (21) and the receiving part (22) is determined in accordance with the fact that the density of R32 is higher than that of air and R32 leaked from the refrigerant circuit stays in the lower part of the casing (11). I have. The transmitting unit (21) is configured to transmit an ultrasonic wave toward the receiving unit (22) disposed above. On the other hand, the receiving unit (22) receives the ultrasonic waves transmitted from the transmitting unit (21). Although not shown, the indoor unit (10) is provided with a temperature sensor for detecting a room temperature. This temperature sensor is configured to output a detected temperature.

Although not shown in the indoor unit (10),
A leak detector is provided. The leak detecting section, the transmitting section (21) and the receiving section (22) constitute a detecting means (20) for detecting a refrigerant leak based on a change in the speed of sound due to a change in the concentration of the refrigerant in the air.

The leak detecting section is configured to detect the time from when the transmitting section (21) transmits the ultrasonic wave to when the receiving section (22) receives the ultrasonic wave as the arrival time.
Further, a predetermined reference time is set in the leak detection unit in advance. During this reference time, when the concentration of R32 in the air is zero, ultrasonic waves are transmitted from the transmitting unit (21) to the receiving unit (22).
Is the time required to reach. Then, the leak detection unit obtains a time difference between the detected arrival time and the reference time,
When the time difference exceeds a predetermined determination value, it is configured to determine that there is a refrigerant leak.

Here, the relationship between the concentration of the refrigerant in the air and the speed of sound will be described.

As shown in the graph of FIG.
As the concentration of 2 increases, the speed of sound in the gas mixture of air and R32 decreases. This is mainly because the density ρ of the mixed gas increases as the concentration of R32 increases. Therefore, when the refrigerant concentration increases, the arrival time increases due to a decrease in the sound speed, and the time difference between the arrival time and the reference time increases.
When the time difference exceeds the determination value, the leak detection unit determines that the refrigerant concentration is equal to or higher than the predetermined value and determines that the refrigerant is leaking. It should be noted that the determination value of the leak detection unit is set so that when the refrigerant concentration becomes 3.3%, it is determined that the refrigerant is leaking. If the concentration of R32, which is a refrigerant, becomes 13% or more, there is a risk of burning, and 13%
This is for detecting refrigerant leakage at a concentration of 1/4 of the above.

On the other hand, as shown in FIG. 2, the speed of sound also changes due to a change in air temperature. Specifically, as the air temperature increases, the speed of sound in the mixed gas increases. This is mainly because the density ρ of the mixed gas decreases as the temperature of the air increases. Therefore, even if the refrigerant concentration in the air does not change, the sound speed changes with the change in the air temperature,
The arrival time changes. For this reason, the time difference between the arrival time and the reference time changes, and there is a possibility that the refrigerant may be determined to be leaking even though the refrigerant concentration has not changed. On the other hand, the leak detecting unit is configured to cancel the influence of the temperature change based on the temperature detected by the temperature sensor and to reliably detect the change in the refrigerant concentration.

-Detection Operation- Next, an operation for detecting refrigerant leakage will be described.

Since the density of the refrigerant is higher than that of the air, FIG.
As shown in (5), the refrigerant leaking from the refrigerant circuit stays at the bottom of the casing (11). When an ultrasonic wave is transmitted from the transmitting unit (21) in this state, the transmitted ultrasonic wave travels through the mixed gas of the refrigerant and the air and reaches the receiving unit (22). Then, the leak detecting unit detects the arrival time until the ultrasonic wave of the transmitting unit (21) reaches the receiving unit (22).

In this case, the sound velocity in the mixed gas is lower than that in the air. For this reason, the arrival time detected by the leak detection unit is longer than the predetermined reference time. Then, when the time difference between the arrival time and the reference time becomes equal to or greater than the determination value after canceling the influence of the temperature change, the leak detection unit detects a refrigerant leak.

-Effects of the First Embodiment- According to the first embodiment, it is possible to detect a change in the speed of sound due to a change in the refrigerant concentration, and to detect a refrigerant leak based on the change. For this reason, it is possible to avoid the problem that the detection performance deteriorates with time as compared with the conventional method of detecting a refrigerant leak using a chemical change or the like. Therefore, it is possible to reliably detect the refrigerant leakage over a long period of time.

Further, since the temperature detected by the temperature sensor is also taken into consideration when judging the refrigerant leakage, the influence of the change in the room temperature on the change in the sound speed is canceled, and the change in the sound speed caused by the change in the refrigerant concentration is canceled. It can be detected reliably.

In this embodiment, R32, which is a slightly flammable substance, is used as the refrigerant. Therefore, if the refrigerant leaks from the refrigerant circuit, it may cause a fire or the like. On the other hand, in the present embodiment, it is possible to reliably detect refrigerant leakage as described above. For this reason, R32 can be used as a refrigerant while avoiding the risk of fire or the like and maintaining reliability.

-Modification of Embodiment 1-In the above embodiment, the transmitting portion (21) is provided in the casing (11).
And the receiver (22) are arranged. However, if the leaked refrigerant hardly stays in the casing (11) structurally, the transmitter (21) and the receiver are provided outside the casing (11). (22) may be attached.

Although the temperature sensor is provided in the indoor unit (10), it may be provided in a remote controller or the like.

[0050]

Second Embodiment A second embodiment of the present invention is a modification of the first embodiment, except that the type of the indoor unit (10) is changed. Accordingly, the arrangement of the transmitting unit (21) and the receiving unit (22) and the configuration of the leak detecting unit are changed. Other configurations are the same as those in the first embodiment.

As shown in FIG. 3, the indoor unit (10) of the present embodiment is configured as a so-called wall-mounted type, and is mounted above the inner wall of the room. A transmitter (21) and a receiver (22) are provided adjacent to the bottom of the casing (11) of the indoor unit (10).

The transmitting section (21) transmits an ultrasonic wave toward the lower part of the indoor unit (10), that is, toward the floor of the room. on the other hand,
The receiving unit (22) receives the ultrasonic wave transmitted from the transmitting unit (21) and reflected on the floor. This is because the refrigerant R32 has a higher density than air, and when leaking from the refrigerant circuit, stays below the indoor unit (10).

As in the first embodiment, the leak detecting section is configured to detect the arrival time required for the ultrasonic wave to reach the receiving section (22) from the transmitting section (21). That is,
In the present embodiment, the time required for the ultrasonic wave transmitted from the transmitting unit (21) to hit the floor surface and be reflected to reach the receiving unit (22) is the arrival time. Therefore, the transmission distance of the ultrasonic wave in the air changes depending on the height of the installation position of the indoor unit (10). For this reason, after the indoor unit (10) is installed, the leak detection unit of the present embodiment confirms that there is no refrigerant leakage, detects the arrival time once, and determines the arrival time at this time as a reference of the leakage detection unit. Set as time.
Then, similarly to the first embodiment, the leak detection unit is configured to determine that a refrigerant leak has occurred when the time difference between the arrival time and the reference time is equal to or greater than a determination value.

In this embodiment, the indoor unit (1
Even after the installation of (0), the transmission distance of the ultrasonic wave may change. For example, indoor unit (10)
The transmission distance changes when an object is placed under the room, when an object that has been turned upside down is removed, or when a person passes under the indoor unit (10). When the transmission distance changes, the arrival time also changes, so that erroneous detection of refrigerant leakage may occur.

On the other hand, the leak detecting section of the present embodiment
When the rate of change of the arrival time is equal to or greater than a predetermined value, that is, when the arrival time changes abruptly, it is configured not to determine that the refrigerant leaks even if the time difference between the arrival time and the reference time is equal to or greater than the determination value. Here, in the case of a refrigerant leak, the sound speed changes continuously and gradually, so that the arrival time also changes gradually. On the other hand, when the transmission distance changes as described above, the arrival time rapidly and discontinuously changes. Therefore, the leak detecting section prevents the erroneous detection of the refrigerant leak by considering the change rate of the arrival time.

-Effects of Second Embodiment- According to the second embodiment, the same effects as those of the first embodiment can be obtained. In addition, the reception of the reflected ultrasonic wave by the receiving unit (22) may cause erroneous detection of refrigerant leakage. However, the leakage detection unit can reliably detect such a small site by considering the rate of change of arrival time. Thus, the reliability of refrigerant leak detection can be improved.

[0057]

Other Embodiments In each of the above embodiments, R32 is used as the refrigerant. However, even when R22 is used, it is possible to detect refrigerant leakage in the same manner. That is, as shown in the graph of FIG.
Also in the case of, the sound speed decreases with an increase in the refrigerant concentration. Therefore, refrigerant leakage can be detected by a configuration similar to that of the above embodiment. In this case, the determination value of the leak detection unit is:
It is preferable to set so that when the refrigerant concentration becomes 7.8%, it is determined that the refrigerant leaks. This concentration value is such that the maximum refrigerant charge of the air conditioner is 300
g / m ³ , which is a value determined by converting this to a volume concentration.

As the refrigerant, not R32 alone, but R32
A mixed refrigerant of 32 and another substance may be used.

When a substance having a density different from that of air is used as the refrigerant, a change in sound speed is similarly caused by refrigerant leakage. For this reason, even if any substance is used as the refrigerant as long as the substance has a different density from that of air, it is possible to detect the refrigerant leakage by utilizing the change in the speed of sound.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an indoor unit according to a first embodiment when viewed from a side.

FIG. 2 is a relationship diagram showing the relationship between the concentration of refrigerant (R32) in air and the speed of sound.

FIG. 3 is a schematic configuration diagram of an indoor unit according to a second embodiment as viewed from a side.

FIG. 4 is a relationship diagram showing the relationship between the concentration of refrigerant (R22) in air and the speed of sound.

[Explanation of symbols]

 (10) Indoor unit (11) Casing (14) Evaporator (heat exchanger) (20) Detection means (21) Transmitter (22) Receiver

Claims (10)

[Claims] 1. A refrigeration system in which refrigerant circulates in a closed circuit refrigerant circuit, wherein a detecting means (20) for detecting refrigerant leakage into a room based on a change in sound speed accompanying a change in refrigerant concentration in room air. ). 2. The refrigeration apparatus according to claim 1, wherein the detecting means (20) includes a transmitting section (21) for transmitting a sound wave into room air, and a receiving section for receiving the sound wave transmitted by the transmitting section (21). A receiving unit (22) for detecting the arrival time required for the sound wave transmitted by the transmitting unit (21) to be received by the receiving unit (22), and detecting a change in the speed of sound based on the detected arrival time. Refrigeration equipment that is configured in. 3. The refrigerating apparatus according to claim 2, further comprising a temperature detecting means for detecting a temperature of the indoor air, wherein the detecting means (20) includes both the detected arrival time and the temperature detected by the temperature detecting means. A refrigeration apparatus configured to detect a change in the speed of sound based on the refrigeration. 4. The refrigeration apparatus according to claim 2, wherein the detection means (20) determines that a refrigerant leak has occurred when a time difference between the detected arrival time and a predetermined reference time is equal to or greater than a predetermined determination value. Device configured as follows. 5. The refrigeration apparatus according to claim 2, wherein the transmitting unit (21) and the receiving unit (22) are each an indoor unit (10).
The refrigeration apparatus is provided in the casing (11), and the transmitting unit (21) is configured to transmit a sound wave toward the receiving unit (22). 6. The refrigeration apparatus according to claim 2, wherein the transmitting unit (21) and the receiving unit (22) are each an indoor unit (10).
The refrigerating apparatus is configured such that the transmitter (21) transmits a sound wave toward the outside of the casing (11) while the receiver (22) receives the reflected sound wave while being provided on the casing (11). 7. The refrigeration apparatus according to claim 6, wherein the detecting means (20) determines that a refrigerant leak has occurred when a time difference between the detected arrival time and a predetermined reference time is equal to or greater than a predetermined determination value. A refrigeration apparatus that is configured not to determine that a refrigerant leak has occurred even if the time difference is equal to or greater than a determination value if a change rate of the arrival time is equal to or greater than a predetermined value. 8. The refrigeration apparatus according to claim 1, wherein the refrigerant is a slightly flammable substance. 9. The refrigeration apparatus according to claim 1, wherein the refrigerant is R32 or a mixed refrigerant containing R32. 10. A refrigeration system for performing a refrigeration cycle by circulating a refrigerant in a refrigerant circuit of a closed circuit is installed in a room, and it is necessary to transmit a sound wave into room air and to receive the transmitted sound wave. A refrigeration system that measures the arrival time, then detects a change in the refrigerant concentration in the indoor air based on the measured change in the arrival time, and then detects refrigerant leakage into the room based on the detected change in the refrigerant concentration. Refrigerant leak detection method.