Leak detection method for flammable refrigerant indoor unit and air conditioning multi-split unit

Abstract

The present invention discloses a method for detecting leaks in combustible refrigerant indoor units and a multi-split air conditioning system employing this method. The method comprises: presetting an initial sleep period for the indoor unit's refrigerant sensor based on design and commissioning parameters; modifying the initial sleep period based on the indoor unit's cumulative operating time and fault frequency; and dynamically adjusting the indoor unit's refrigerant sensor's sleep period based on the indoor unit's operating status, enabling the indoor unit's refrigerant sensor to perform intermittent leak detection. For large multi-split air conditioning systems, this method reduces the operating time of the refrigerant sensor, contributing to energy savings and improved economic efficiency.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a leakage detection method for a flammable refrigerant indoor unit and an air-conditioning multi-unit unit using the method. Background Art

[0002] With increasing environmental protection requirements, the environmental advantages of combustible refrigerants are gaining widespread recognition, primarily due to their low global warming potential (GWP), zero ozone depletion potential (ODP), and the natural origin of some refrigerants. Furthermore, combustible refrigerants offer the following advantages: excellent thermodynamic properties, improved energy efficiency, reduced electricity consumption, and thus indirectly lowering carbon emissions associated with power generation (especially in regions with a high proportion of coal-fired power generation); and minimal environmental impact throughout their lifecycle. The extraction and purification process for combustible refrigerants emits far less carbon than the synthesis of fluorinated refrigerants, requiring no special decomposition process and evaporating naturally.

[0003] Environmentally friendly refrigerants are gaining increasing attention in the refrigeration industry. The use of flammable refrigerants in air conditioning, heat pumps, and other fields is gradually increasing. Flammable refrigerants such as R32 and R290 have also entered the air conditioning industry. However, flammable refrigerants are refrigerants that can ignite under certain conditions. These refrigerants typically have low flash points or flammability limits, and can ignite or explode when exposed to open flames, high temperatures, or sparks. Therefore, their safety requires strict control.

[0004] Combustible refrigerants meet global environmental requirements, but their flammability also presents safety risks. Monitoring refrigerant leaks in refrigeration systems using flammable refrigerants has become a crucial issue. A common approach is to use refrigerant sensors to detect leaks, particularly in indoor environments. This prevents excessive refrigerant levels in applications, reaching the lower flammable limit and potentially causing combustion or explosions, resulting in property damage or casualties.

[0005] Existing refrigerant sensors are monitored in real time, which is relatively safe for a single system. However, for large-scale multi-split air conditioning system projects, there are a large number of indoor units. The diverse usage time of these indoor units requires all refrigerant sensors to be monitored in real time. However, the real-time power supply of a large number of refrigerant sensors will lead to energy waste. Summary of the Invention

[0006] The present invention proposes a leak detection method for a flammable refrigerant indoor unit and an air-conditioning multi-split unit using the method, so as to solve the energy waste problem caused by the real-time power supply of a large number of refrigerant sensors, extend the service life of the sensors, and reduce maintenance costs.

[0007] The technical solution adopted by the present invention is to propose a leakage detection method for a combustible refrigerant indoor unit, comprising:

[0008] Preset the initial dormancy period of the indoor unit refrigerant sensor according to the design and commissioning parameters;

[0009] Correct the initial sleep cycle according to the accumulated working time and fault number of the indoor unit;

[0010] The dormancy period of the indoor unit refrigerant sensor is calculated according to the operating status of the indoor unit, so that the indoor unit refrigerant sensor performs intermittent leakage detection.

[0011] Furthermore, the correction includes: a time correction parameter A, a fault correction parameter B and a high voltage correction parameter C.

[0012] In one embodiment, the present invention provides a method for detecting leakage of a flammable refrigerant indoor unit, comprising the following steps:

[0013] Preset the initial sleep period W of the indoor unit;

[0014] Select the time correction parameter A and fault correction parameter B of the indoor unit;

[0015] Determine whether the indoor unit is in the on state. If so, determine the high-voltage correction parameter C according to the high-voltage area of ​​the unit, and then calculate the sleep period of the indoor unit refrigerant sensor in the on state; if not, calculate the sleep period of the indoor unit refrigerant sensor in the off state.

[0016] Furthermore, when the indoor unit is in the on state, the dormant period Q of the indoor unit refrigerant sensor is calculated as follows: Q=A*B*C*W.

[0017] Furthermore, when the indoor unit is in the off state, the dormancy period Q of the indoor unit refrigerant sensor is calculated according to the following formula: Q=A*B*N*W, where N is a value greater than 1.

[0018] Preferably, the time correction parameter A of the indoor unit is taken as follows:

[0019] .

[0020] Preferably, the fault correction parameter B of the indoor unit is taken as follows:

[0021] .

[0022] Preferably, the high-pressure correction parameter C is taken as follows:

[0023] .

[0024] Preferably, if the calculated sleep period Q is less than the minimum value T, the system is controlled according to the minimum value.

[0025] Preferably, the detection time of the internal unit refrigerant sensor each time is t.

[0026] Furthermore, the indoor unit refrigerant leakage detection method proposed by the present invention further includes the indoor unit sleep execution step:

[0027] Determine whether the calculated sleep cycle of the indoor unit is less than the minimum value T. If so, execute the sleep cycle according to the minimum value; if not, operate according to the actually calculated sleep cycle.

[0028] When the indoor unit refrigerant sensor alarms, it enters real-time monitoring and switches to manual recovery.

[0029] The present invention also provides an air-conditioning multi-split unit, comprising an outdoor unit and an indoor unit, wherein the indoor unit adopts the above-mentioned combustible refrigerant indoor unit leakage detection method.

[0030] Compared with the prior art, the technical solution proposed by the present invention has the following beneficial effects:

[0031] 1. The present invention fully considers the cumulative operating time and number of faults in large multi-split air-conditioning systems. On the basis of ensuring safety and reliability, it dynamically adjusts the sleep cycle of the indoor unit, performs intermittent detection on the indoor unit, reduces the working time of the refrigerant sensor, and extends the service life of the refrigerant sensor.

[0032] 2. For large multi-split air-conditioning systems, there are a large number of refrigerant sensors. Reducing the working time of refrigerant sensors is beneficial to energy saving and improving economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, wherein:

[0034] Figure 1 It is a system diagram of a multi-split air conditioning unit;

[0035] Figure 2 This is a block diagram of the principle of determining the dormancy period of the indoor unit refrigerant sensor according to the present invention;

[0036] Figure 3 This is the control flow chart of the dormant cycle of the indoor unit refrigerant sensor;

[0037] Figure 4 This is the execution flow chart of the internal machine in sleep state.

[0038] in:

[0039] 1 Compressor, 2 Four-way valve, 3 Outdoor heat exchanger, 4 Expansion valve, 5 Indoor unit, 6 Stop valve, 7 Refrigerant sensor, 8 Temperature sensor, 9 Pressure sensor.

[0040] W preset initial sleep period;

[0041] A time correction parameter;

[0042] B. Fault correction parameters;

[0043] C high pressure correction parameter;

[0044] Q sleep cycle;

[0045] tleak detection time;

[0046] T is the minimum value of the sleep period. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and do not constitute a limitation of the present invention.

[0048] The terms used in this specification are only for describing specific embodiments and are not intended to limit the present invention. Unless otherwise specifically stated, the relative arrangement of parts and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of protection of the present invention.

[0049] The techniques, methods and equipment known to those skilled in the art are not discussed in detail in this specification, but where appropriate, such techniques, methods and equipment should be considered as part of this specification. Any specific values ​​in this specification should be interpreted as merely exemplary and not as limiting the present invention.

[0050] For ease of description, positional terms used in this specification, such as "above," "to the left of," and "in front of," are intended solely to describe the spatial relationship between a component and other components of the illustrated embodiments. When the components are positioned differently, their relative positions will vary. Therefore, the positional relationships described in the illustrated embodiments should not limit the present invention. Furthermore, it should be noted that the use of terms such as "first" and "second" in this specification is intended solely to distinguish similar components and does not imply a sequential order. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0051] The concept of the present invention is to reduce the working time of the refrigerant sensor by intermittently detecting the refrigerant leakage of the indoor unit, thereby extending the service life of the refrigerant sensor and reducing energy consumption while ensuring safety and reliability.

[0052] Figure 1 This is a system diagram of a multi-split air conditioning system. The system consists of a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an electronic expansion valve 4, and multiple parallel indoor units 5, connected by pipes. Each parallel branch is equipped with a shutoff valve 6. The compressor exhaust pipe is equipped with a temperature sensor 8 and a pressure sensor 9.

[0053] When the air-conditioning multi-split unit is cooling, the refrigerant is compressed by the compressor 1 and then discharged as high-temperature and high-pressure refrigerant gas. The gas is introduced into the outdoor heat exchanger 3 through the four-way valve 2 and condensed into a high-pressure and normal-temperature refrigerant liquid. It is then throttled by the electronic expansion valve 4 and becomes a low-temperature and low-pressure refrigerant liquid. The liquid is introduced into the indoor unit 5 and evaporates into a low-temperature and low-pressure refrigerant gas after heat exchange with the indoor air. It is then returned to the compressor 1 through the four-way valve 2 for recirculation.

[0054] When the air-conditioning multi-split unit is heating, the refrigerant is compressed by the compressor 1 and discharges high-temperature and high-pressure refrigerant gas. The gas is introduced into the indoor unit 5 through the four-way valve 2 and exchanges heat with the indoor air, and then condenses into a high-pressure and normal-temperature refrigerant liquid. It is then throttled by the electronic expansion valve 4 and becomes a low-temperature and low-pressure refrigerant liquid. The liquid is introduced into the outdoor heat exchanger 3, evaporates into a low-temperature and low-pressure refrigerant gas after heat exchange, and then returns to the compressor 1 through the four-way valve 2 for recirculation.

[0055] As mentioned above, flammable refrigerants are widely used due to their environmental advantages, but their flammable nature poses a safety hazard. To solve this problem, a common method is to use refrigerant sensors to detect refrigerant leaks, especially to monitor the indoor environment to prevent the refrigerant content in the application area from being too high and reaching the lower flammable limit, thereby causing combustion or explosion, resulting in property damage or casualties. Figure 1 As shown, each indoor unit 5 is equipped with a refrigerant sensor 7. When the refrigerant sensor detects refrigerant leakage from the indoor unit reaching a certain concentration, an alarm is triggered to prevent dangerous accidents. However, for large-scale multi-split air conditioning system projects, there are many indoor units. The diverse usage time of these indoor units requires that all refrigerant sensors be monitored in real time. However, the constant power supply of a large number of refrigerant sensors can lead to energy waste.

[0056] Through a large amount of experimental data, it was found that the longer the cumulative running time of the air-conditioning unit, the greater the probability of refrigerant leakage; the higher the number of failures of the air-conditioning unit, the greater the probability of refrigerant leakage; the higher the high pressure of the air-conditioning unit, the greater the probability of refrigerant leakage. In addition, when the indoor unit is in the off state, the probability of leakage may be smaller. Based on these characteristics, the idea of ​​the present invention is: according to the design parameters and debugging status of the air-conditioning multi-split unit, an initial dormant cycle is preset to make the refrigerant sensor of the indoor unit work intermittently, so that the refrigerant sensor of the indoor unit is powered off and enters the dormant cycle after working for a period of time, and enters the working period again after the dormant cycle ends, thereby achieving the purpose of reducing energy consumption.

[0057] The above-mentioned dormancy cycle specifically includes the following three aspects:

[0058] 1. Preset the initial dormancy period of the refrigerant sensor while ensuring the safety and reliability of the system;

[0059] 2. Modify the preset initial sleep week based on the accumulated operating time and number of failures of the air conditioning unit;

[0060] 3. Dynamically adjust the preset initial sleep cycle according to whether the indoor unit is working.

[0061] The present invention reduces the working time of the refrigerant sensor by setting a sleep (power-off) period for the indoor unit refrigerant sensor and performing intermittent detection of indoor unit refrigerant leakage, thereby extending the service life of the refrigerant sensor and reducing energy consumption while ensuring safety and reliability.

[0062] like Figure 2 As shown, the leakage detection method for a flammable refrigerant indoor unit proposed by the present invention includes:

[0063] Preset the initial dormancy period of the indoor unit refrigerant sensor according to the design and commissioning parameters;

[0064] Correct the initial sleep cycle according to the accumulated working time and fault number of the indoor unit;

[0065] The dormancy period of the indoor unit refrigerant sensor is calculated according to the operating status of the indoor unit, so that the indoor unit refrigerant sensor performs intermittent detection.

[0066] The above corrections include: time correction parameter A, fault correction parameter B and high voltage correction parameter C.

[0067] After the preset initial dormancy cycle is set, the system automatically detects the number of refrigerant sensors in the multi-split indoor unit, and then obtains the cumulative operating time and fault count of each indoor unit through engineering memory. The time correction parameter A, which reflects the cumulative operating time of the indoor unit (calculated from the normal operation time after commissioning), and the fault correction parameter (accumulated fault count) B are selected according to the table below:

[0068] Time correction parameter A value

[0069] .

[0070] Fault correction parameter B value

[0071] .

[0072] The indoor unit parameters can be used to distinguish whether an indoor unit is active or not. The sleep period of an indoor unit that is powered off can be longer. If the sleep period of an active indoor unit is Q, the sleep period of an inactive indoor unit can be N times that of the active indoor unit. N is a value greater than 1 and ranges from [1, 10]. For example, if the sleep period of an active indoor unit is 5 minutes, the sleep period of an inactive indoor unit is twice that of the active indoor unit, or 10 minutes.

[0073] As an embodiment, the state of the internal unit of the unit is corrected by the high pressure of the unit system. The value range of the high pressure correction parameter C is as follows:

[0074] High pressure correction parameter C value

[0075] .

[0076] The above preset initial sleep cycle and correction parameter data are derived from a large amount of experimental statistical data. The above data may vary for different units and different application environments.

[0077] Figure 3 This is a control flow chart of the dormant period of the internal refrigerant sensor. The method for detecting flammable refrigerant leakage in an internal unit proposed by the present invention comprises the following steps:

[0078] Preset the initial sleep period W of the indoor unit;

[0079] Select the time correction parameter A and fault correction parameter B of the indoor unit;

[0080] Determine whether the indoor unit is in the on state. If so, determine the high-voltage correction parameter C according to the high-voltage area of ​​the unit, and then calculate the sleep period Q of the indoor unit refrigerant sensor in the on state; if not, calculate the sleep period Q of the indoor unit refrigerant sensor in the off state.

[0081] When the indoor unit is on, the dormant period Q of the indoor unit refrigerant sensor is calculated as follows: Q=A*B*C*W.

[0082] When the indoor unit is turned off, the sleep period Q of the indoor unit refrigerant sensor is calculated according to the following formula: Q=A*B*N*W, where N should be a value greater than 1. The value of N is based on the fact that the probability of leakage when the indoor unit is turned off is smaller, so the sleep period of the indoor unit can be increased when the unit is turned off.

[0083] The present invention calculates the dormancy period Q of each refrigerant sensor by presetting an initial dormancy period and modifying parameters; and intelligently adjusts the operating frequency of the indoor refrigerant sensor to extend its service life, reduce energy consumption, and ensure safety.

[0084] The following example illustrates the calculation of the sleep cycle:

[0085] First, the initial dormancy period W of the indoor unit refrigerant sensor is preset to 10 minutes. According to the record, the cumulative operating time of the multi-split air conditioning system from installation and commissioning to operation is 1 year. The number of fault alarms during the operation of the indoor unit is 3. At this time, the time correction parameter A is 1, the fault correction parameter B is 0.9, the indoor unit is in the power-on state, the saturation temperature corresponding to the high pressure is 52°C, and the corresponding high pressure correction parameter is 0.9. At this time, the dormancy period of the refrigerant sensor of the indoor unit is

[0086] Q= A*B*C*W=1*0.9*0.9*10=8.1.

[0087] After the indoor unit's sleep cycle is determined, the following plan is implemented: After a period of time t, the indoor unit's refrigerant sensor detects the refrigerant and enters sleep cycle Q. During this period, the indoor unit's refrigerant sensor is powered off. After the sleep cycle ends, it is powered back on and enters the leak detection period. During the power-on detection period t, a refrigerant leak is determined based on whether the detected refrigerant concentration reaches the refrigerant sensor alarm threshold. An alarm is triggered when the detected refrigerant concentration reaches the alarm threshold.

[0088] Figure 4 This is the execution flow chart of the internal machine in sleep state, including the following steps:

[0089] After the indoor unit sleep cycle Q is calculated, it is determined whether the sleep cycle is less than the set minimum value T. If so, the sleep cycle is executed according to the minimum value T; if not, it is executed according to the actually calculated sleep cycle.

[0090] The detection time of each indoor unit refrigerant sensor is t, which is generally 60 seconds. To prevent the refrigerant sensor from switching frequently, the sleep cycle Q cannot be less than 1 minute. If the sleep cycle Q is less than 1 minute, it will be forced to be executed as 1 minute.

[0091] When the refrigerant sensor of the indoor unit is powered on for 60 seconds, if the indoor unit refrigerant sensor does not alarm, it can enter the sleep cycle. After the power is cut off for 8.1 minutes, the refrigerant sensor is powered on again; if the refrigerant sensor alarms, the indoor unit refrigerant sensor must be powered on until the operator manually restores it.

[0092] The present invention also provides an air conditioning multi-split unit whose indoor units utilize the aforementioned flammable refrigerant indoor unit leak detection method. For cooling and heating systems with numerous indoor units, which often require numerous indoor refrigerant sensors, reducing the operating time of these refrigerant sensors not only reduces energy consumption but also extends the service life of the refrigerant sensors.

[0093] The present invention dynamically adjusts the detection frequency of the indoor unit refrigerant sensor based on multiple factors such as installation time, operation time, system parameters, etc., and adopts different detection strategies for the operating status of the indoor unit when it is turned on and when it is turned off, which is beneficial to improving economic benefits and reducing energy consumption while improving reliability.

[0094] The present invention also provides a safety protection mechanism, which automatically switches to a real-time detection mode when an alarm is detected.

[0095] The present invention proposes a leakage detection method for flammable refrigerant indoor units, and the installation and debugging data, operating data, and calculation formulas of air-conditioning multi-split units are all compiled into a computer program of a control chip. The method can quickly calculate the indoor unit sleep cycle based on actual operating data, and control the indoor unit refrigerant sensor to perform intermittent detection, which is efficient and safe.

[0096] The above description is only a specific embodiment of the present invention. It should be pointed out that any modifications, equivalent replacements and changes made within the spirit and framework of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for detecting leakage of a combustible refrigerant indoor unit, characterized in that: include: Preset the initial dormancy period of the indoor unit refrigerant sensor according to the design and commissioning parameters; Correct the initial sleep cycle according to the accumulated working time and fault number of the indoor unit; Dynamically adjusting the dormancy period of the indoor unit refrigerant sensor according to the operating state of the indoor unit, so that the indoor unit refrigerant sensor performs intermittent leak detection, wherein the operating state includes an on state and an off state; The correction includes: time correction parameter A, fault correction parameter B and high voltage correction parameter C.

2. The leak detection method according to claim 1, wherein: The following steps are involved: Preset the initial sleep cycle W of the indoor unit; Select the time correction parameter A and fault correction parameter B of the indoor unit; Determine whether the indoor unit is in the on state. If so, determine the high-voltage correction parameter C according to the high-voltage area of ​​the unit, and then calculate the sleep period of the indoor unit refrigerant sensor in the on state; if not, calculate the sleep period of the indoor unit refrigerant sensor in the off state.

3. The leak detection method according to claim 2, wherein: When the indoor unit is on, the dormant period Q of the indoor unit refrigerant sensor is calculated as follows: Q=A*B*C*W.

4. The leak detection method according to claim 2, wherein: When the indoor unit is turned off, the dormant period Q of the indoor unit refrigerant sensor is calculated as follows: Q=A*B*N*W, where N is a value greater than 1.

5. The leakage detection method according to claim 2, wherein: The time correction parameter A of the indoor unit is taken as follows: When the cumulative working time is less than or equal to 1 year, the time correction parameter A is 1; When the cumulative working time is greater than 1 and less than or equal to 3 years, the time correction parameter A is 0.9; When the cumulative working time is greater than 3 and less than or equal to 5 years, the time correction parameter A is 0.7; When the cumulative working time is greater than 5 years, the time correction parameter A is 0.

5.

6. The leakage detection method according to claim 2, wherein: The fault correction parameter B of the indoor unit is taken as follows: When the number of faults is less than or equal to 2, the fault correction parameter B is 1; When the number of faults is greater than 2 and less than or equal to 4, the fault correction parameter B is 0.8; When the number of faults is greater than 4 and less than or equal to 6, the fault correction parameter B is 0.6; When the number of faults is greater than 6, the fault correction parameter B is 0.

4.

7. The leakage detection method according to claim 2, wherein: The high pressure correction parameter C is taken as follows: When the saturation temperature corresponding to high pressure is less than or equal to 50°C, the high pressure correction parameter C is 1; When the saturation temperature corresponding to high pressure is greater than 50 and less than or equal to 55°C, the high pressure correction parameter C is 0.9; When the saturation temperature corresponding to high pressure is greater than 55 and less than or equal to 58°C, the high pressure correction parameter C is 0.7; When the saturation temperature corresponding to high pressure is greater than 58°C, the high pressure correction parameter C is 0.

4.

8. The leakage detection method according to claim 3 or 4, characterized in that: If the calculated sleep period Q is less than 1 minute, it is controlled as 1 minute.

9. The leak detection method according to claim 1, wherein: The leakage detection time of the indoor refrigerant sensor is t.

10. The leakage detection method according to claim 2, wherein: It also includes the steps for executing the internal machine sleep mode: Determine whether the calculated sleep cycle of the indoor unit is less than the minimum value T. If so, the sleep cycle is executed according to the minimum value T; if not, the indoor unit is operated according to the actually calculated sleep cycle.

11. The leakage detection method according to claim 10, wherein: When the indoor unit refrigerant sensor alarms, it switches to manual recovery.

12. An air-conditioning multi-split unit, comprising an outdoor unit and an indoor unit, characterized in that: The indoor unit adopts the leakage detection method for a flammable refrigerant indoor unit according to any one of claims 1 to 11.

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