Intelligent defrosting method and air conditioning system

Abstract

This invention discloses an intelligent defrosting method and an air conditioning system. The intelligent defrosting method includes: Step 1, monitoring the refrigerant saturation temperature of the heat exchanger; Step 2, determining whether the heat exchanger is frosted and the frosting state based on changes in the refrigerant saturation temperature; Step 3, applying different defrosting criteria to different frosting states. This invention provides different defrosting criteria for different frosting states, thereby making the defrosting process more accurate.

Description

Technical Field

[0001] This invention relates to the technical field of air conditioning systems, and more particularly to an intelligent defrosting method. Background Technology

[0002] In traditional air-cooled heat exchange air conditioning systems, defrosting is a crucial operational process. During heating mode, frost may form on the evaporator surface, reducing heat exchange efficiency. To restore normal heat exchange performance, the system needs to perform a defrosting operation, which removes the frost and ice from the evaporator surface.

[0003] However, traditional defrosting methods typically involve periodically running the compressor and then using a temperature sensor to detect the temperature of the tube to determine if defrosting is necessary. This simple defrosting method has some problems.

[0004] Inaccurate Judgment: Because only one defrost temperature sensor is used to determine the temperature, it is impossible to accurately determine whether there is frost or not on the evaporator surface. This may lead to delayed defrosting when needed, thus affecting the system's heat exchange efficiency and performance. Traditional defrosting methods typically use only one defrost temperature sensor to measure the evaporator's defrost temperature. This design makes it difficult to accurately determine whether the entire evaporator surface is frosted, and to what extent.

[0005] Energy waste: Current defrosting methods typically involve periodically running the compressor for defrosting, with the defrosting intervals preset. This fixed-interval defrosting method cannot be adjusted according to actual needs, potentially leading to incomplete defrosting or defrosting without actual frost, thus affecting system operating efficiency. Periodically running the compressor for defrosting can result in energy waste, especially when defrosting is not actually needed.

[0006] Relying on experience and predefined settings: Current defrosting methods typically rely on experience and predefined thresholds to determine when to defrost. This method cannot flexibly adapt to different environmental conditions and usage scenarios, and therefore may not accurately determine the timing of defrosting in some situations.

[0007] Lack of intelligence: Traditional methods lack intelligent capabilities and cannot make flexible defrosting decisions based on actual conditions, such as adjusting the defrosting cycle according to factors such as the degree of frost formation and ambient temperature.

[0008] Therefore, how to provide a method that can accurately identify whether a heat exchanger has frost or not, and determine the defrosting process based on the degree of frost, is a technical problem that the industry needs to solve. Summary of the Invention

[0009] To address the technical problems of inaccurate defrosting identification and determination in existing technologies, this invention proposes an intelligent defrosting method and an air conditioning system.

[0010] The intelligent defrosting method proposed in this invention includes:

[0011] Step 1: Monitor the refrigerant saturation temperature of the heat exchanger;

[0012] Step 2: Determine whether the heat exchanger is frosted and the frosting state when frosting occurs by observing the change in the refrigerant saturation temperature.

[0013] Step 3: Use different defrosting criteria to defrost the material in different frosting states.

[0014] Furthermore, at least one temperature sensor is installed in the middle of the heat exchanger's branch pipe to monitor the refrigerant saturation temperature.

[0015] Furthermore, determining whether the heat exchanger is frosted by observing the change in the refrigerant's saturated temperature includes:

[0016] If the refrigerant saturation temperature does not decrease, it is determined that the heat exchanger is not frosted.

[0017] Furthermore, determining whether the heat exchanger is frosted by observing the change in the refrigerant's saturated temperature includes:

[0018] When the refrigerant saturation temperature drops, it is determined that the heat exchanger is frosted.

[0019] Furthermore, the change in the refrigerant saturation temperature specifically refers to the time taken for the refrigerant saturation temperature to decrease by one unit temperature.

[0020] Furthermore, the unit temperature is 1°C.

[0021] Furthermore, determining the frosting state of the heat exchanger during frosting based on the change in the refrigerant saturation temperature includes:

[0022] When the time taken for the refrigerant saturated temperature to drop by one unit temperature is greater than zero and less than or equal to the first time, the frosting state of the heat exchanger is in the rapid frosting range.

[0023] When the time taken for the refrigerant saturated temperature to drop by one unit temperature is greater than the first time and less than or equal to the second time, the frosting state of the heat exchanger is in the slow frosting range.

[0024] When the time taken for the refrigerant saturated temperature to drop by one unit temperature is greater than the second time, the heat exchanger is in the frosting preparation interval.

[0025] Furthermore, different defrosting criteria are used to defrost the material under different frosting conditions, including:

[0026] When the frosting state is in the frosting preparation interval, determine whether the refrigerant saturation temperature is greater than the saturation temperature threshold. If it is greater, return to step 1. If it is less than or equal to, determine whether the compressor's running time has reached the first running time. If it has, start defrosting until the defrosting exit condition is met. If it has not been met, return to step 1.

[0027] Furthermore, different defrosting criteria are used to defrost the material under different frosting conditions, including:

[0028] When the frosting state is in the slow frosting range, monitor the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe;

[0029] If the compressor's operating time exceeds the second operating time, and the refrigerant temperature in the heat exchanger's inlet pipe is lower than the first defrosting temperature, then defrosting begins until the defrosting exit condition is met; otherwise, the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe continue to be monitored.

[0030] Furthermore, different defrosting criteria are used to defrost the material under different frosting conditions, including:

[0031] When the frosting state is in the rapid frosting range, monitor the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe;

[0032] If the compressor's operating time exceeds the third operating time and the refrigerant temperature in the heat exchanger's inlet pipe is lower than the second defrost temperature, defrosting begins until the defrost exit condition is met; otherwise, the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe continue to be monitored.

[0033] Furthermore, the defrosting exit condition is that the refrigerant temperature in the inlet pipe of the heat exchanger is greater than the defrosting exit temperature.

[0034] Furthermore, before determining the refrigerant temperature in the inlet pipe of the heat exchanger, the outdoor ambient temperature is detected, and the corresponding defrosting temperature threshold value is selected based on the outdoor ambient temperature value.

[0035] The air conditioning system proposed in this invention includes an outdoor heat exchanger, which is defrosted using the intelligent defrosting method described in the above technical solution.

[0036] This invention detects the refrigerant saturation temperature of the outdoor unit's heat exchanger to obtain changes in that temperature, thereby revealing changes in the system's low-pressure. Based on these low-pressure changes, it determines whether the outdoor heat exchanger has frosted, and if so, the specific frosting state or stage. Different defrosting criteria are applied to different frosting states, allowing the outdoor heat exchanger to defrost according to specific circumstances. This avoids the inaccurate defrosting identification and determination problems caused by fixed defrosting criteria. Attached Figure Description

[0037] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0038] Figure 1 This is a main flowchart of an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the temperature sensing bag configuration according to an embodiment of the present invention.

[0040] Figure 3 This is a detailed flowchart of an embodiment of the present invention.

[0041] Figure 4 This is the frosting state classification table of the present invention.

[0042] Figure 5 This is a schematic diagram illustrating the configuration of the temperature-sensing bag according to another embodiment of the present invention. Attached image description:

[0044] 1. Outdoor heat exchanger

[0045] 2. Temperature sensing bulb in the tube.

[0046] 3. Defrosting temperature sensor.

[0047] 4. Diverter. Detailed Implementation

[0048] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0050] like Figure 1 As shown, the intelligent defrosting method of the present invention mainly includes the following steps.

[0051] Step 1: Monitor the refrigerant saturation temperature of the heat exchanger;

[0052] Step 2: Determine whether the heat exchanger is frosted and the frosting state when frosting occurs by observing the change in the refrigerant saturation temperature.

[0053] Step 3: Use different defrosting criteria to defrost the material in different frosting states.

[0054] The technical principle of this invention lies in the ability to directly predict the unit's operating status based on changes in system parameters during heating mode. For example, when the unit is heating without frost and operating stably, the air conditioning system parameters are relatively stable and do not change significantly. When frost forms during heating, the system's low pressure changes significantly before and after frost formation. After frost, the system's low pressure drops, and the thicker the frost layer, the worse the heat exchange effect, and the lower the system's low pressure. Therefore, this invention adds a tube-mounted temperature sensor to the heat exchanger (which becomes the condenser during heating) of the outdoor unit of the air conditioner. This allows for real-time monitoring of changes in the system's low pressure, i.e., monitoring of the refrigerant saturation temperature, during heating mode.

[0055] The degree of frost formation on a heat exchanger is related not only to temperature but also to air humidity. Higher humidity leads to faster and thicker frost formation. Therefore, existing technologies typically employ multiple sensors, such as temperature sensors, humidity sensors, and frost thickness sensors, to monitor the evaporator surface for intelligent defrosting. Data fusion from these sensors allows for more accurate determination of evaporator frost formation, enabling precise defrosting when necessary. However, this invention uses the technique of monitoring the refrigerant saturation temperature of the heat exchanger. This refrigerant saturation temperature can be directly converted into refrigerant pressure. Therefore, in heating mode, monitoring the refrigerant saturation temperature can effectively monitor the system evaporation pressure, thus monitoring the system's low pressure. While pressure sensors can be used to monitor system low pressure in alternative embodiments, they are 8-10 times more expensive than temperature sensors. Therefore, in the preferred embodiment of this invention, a temperature sensor is used to monitor the refrigerant saturation temperature, which is then converted into system evaporation pressure.

[0056] Temperature sensors, linear electrical conduction (Capillary Tube), infrared thermometry, and other methods can be used to monitor the saturation temperature of the refrigerant.

[0057] A temperature sensor is used to directly measure the saturation temperature of the refrigerant within the heat exchanger. The sensor can be a thermocouple, a thermistor (such as a PT100), or a semiconductor temperature sensor. The sensor converts the measured temperature value into an electrical signal, which is then transmitted to the control system via an electrical connection.

[0058] Using linear electrical conduction as a temperature sensor, the saturation temperature of the refrigerant is measured by the temperature characteristics of linear electrical conduction.

[0059] Infrared thermometers can be used to measure the temperature of an object's surface non-contactly. By measuring the surface of a heat exchanger using infrared thermometry, an approximate saturation temperature value can be obtained.

[0060] In one embodiment, the refrigerant saturation temperature of the heat exchanger is monitored by installing at least one temperature sensor (such as a tube-mounted temperature sensor) in the middle of the heat exchanger's branch pipes.

[0061] After obtaining the refrigerant's saturation temperature, determine the type of refrigerant used, such as R-410A, R-134a, or R-22. Different refrigerants have different pressure-temperature relationships. Then, select the correct refrigerant property table and use it to find the saturation pressure value corresponding to the given saturation temperature. The property table will list the refrigerant saturation pressure at different temperatures.

[0062] In one embodiment, determining whether a heat exchanger is frosted by observing changes in the refrigerant saturation temperature includes:

[0063] If the refrigerant saturation temperature does not drop, it is determined that the heat exchanger is not frosted.

[0064] When the refrigerant saturation temperature drops, it is determined that the heat exchanger is frosting.

[0065] While the reasons for a drop in refrigerant saturation temperature are not limited to heat exchanger frosting, they could also be due to system pressure drops caused by malfunctions, changes in refrigerant composition, etc. However, under normal circumstances, a drop in refrigerant saturation temperature is mainly caused by factors such as evaporator surface frosting or low ambient temperature. Both evaporator surface frosting and low ambient temperature can lead to evaporator frosting.

[0066] In one embodiment, the change in the refrigerant saturation temperature referred to in this invention specifically refers to the time taken for the refrigerant saturation temperature to decrease by one unit temperature. This can be expressed by the formula: Where ΔT 外管中 The difference between the current refrigerant saturation temperature and the previous refrigerant saturation temperature can be expressed by the formula ΔT. 外管中 = Current time T 外管中 -T a moment ago 外管中 The difference, i.e., ΔT 外管中 =T 外管中2 -T 外管中1 T 外管中2 Indicates the current time T 外管中 T 外管中1 Indicates the previous moment T 外管中 t represents unit temperature, and d represents the differential equation.

[0067] This invention determines the approximate stage of frosting on a heat exchanger by calculating the time required for the refrigerant saturation temperature to drop by one unit. When it takes a long time for the refrigerant saturation temperature to drop by one unit, it indicates that the heat exchanger is in the pre-frosting stage. When the time required is very short, it suggests that the heat exchanger is likely in the rapid frosting stage. If the time required for the refrigerant saturation temperature to drop by one unit falls between these two scenarios, the heat exchanger is likely in the slow frosting stage.

[0068] In one specific embodiment, a unit temperature is 1°C, i.e., t = 1°C. Therefore, the change in the saturated temperature of the refrigerant can be specifically expressed as follows: Those skilled in the art can adjust the unit temperature value according to the specific environmental conditions and the specific heat exchanger, and it is not limited to a value of 1℃.

[0069] In one embodiment, the frosting state of the heat exchanger when frosting is determined by the change in the refrigerant saturation temperature includes the following three cases.

[0070] When the time taken for the refrigerant saturated temperature to drop by one unit temperature is greater than zero and less than or equal to the first time, the heat exchanger is in the rapid frosting range.

[0071] When the time taken for the refrigerant saturated temperature to drop by one unit temperature is greater than the first time and less than or equal to the second time, the heat exchanger is in the slow frosting range.

[0072] When the time required for the refrigerant saturation temperature to drop by one unit temperature is greater than the second time, the heat exchanger is in the frosting state of the pre-frosting interval.

[0073] In one embodiment, using different defrosting criteria for different frosting states includes the following aspects.

[0074] When the frosting state is in the pre-frosting interval, it is determined whether the refrigerant saturation temperature is greater than the saturation temperature threshold. If it is, the process returns to step 1, i.e., it continues to monitor the refrigerant saturation temperature of the heat exchanger, and then judges the frosting status of the heat exchanger based on the changes in the refrigerant saturation temperature. If the refrigerant saturation temperature is less than or equal to the saturation temperature threshold, it is determined whether the compressor's operating time has reached the first operating time. If it has, defrosting begins until the defrosting exit condition is met. If it has not reached the first operating time, the process returns to step 1, i.e., it continues to monitor the refrigerant saturation temperature of the heat exchanger, and then judges the frosting status of the heat exchanger based on the changes in the refrigerant saturation temperature.

[0075] Regarding the value of the saturation temperature threshold c, since condensate needs to be below 0 degrees Celsius on the heat exchanger fins to freeze or frost, and frost formation causes the saturation temperature to drop, the saturation temperature threshold generally needs to be below 0 degrees Celsius and also below the outdoor ambient temperature. For example, c < 0, and T 室外环境 -c≤2. Where T 室外环境 This refers to the outdoor ambient temperature.

[0076] When the above principles determine the area to be in the frosting preparation stage, it means that the air conditioning unit currently has slight frosting or is just in the frosting preparation stage. At this time, T 外管中 While the temperature is indeed decreasing, it has little impact on the air conditioner's heat exchange and there will be no significant performance degradation. Therefore, defrosting is not required, which avoids the traditional defrosting determination method where the unit directly enters defrosting as soon as the pipe temperature drops after running for a period of time, thus affecting user comfort.

[0077] The refrigerant saturation temperature is monitored after the compressor has been running for a period of time. The unit does not monitor the refrigerant saturation temperature during the defrosting process to avoid short-term misjudgment. In addition, even if the refrigerant saturation temperature is monitored throughout the process, the judgment logic of this invention can still obtain the correct judgment result.

[0078] For example, during defrosting, the unit operates in cooling mode, and the outdoor unit's fan is off. At this time, the high-temperature refrigerant discharged from the compressor enters the outdoor unit's heat exchanger (which is now the condenser) to defrost. The pipe temperature of the outdoor unit's heat exchanger gradually increases and does not decrease. Generally, when the outdoor defrost sensing temperature (the refrigerant temperature in the heat exchanger's inlet pipe) reaches 10°C or 12°C, defrosting stops. After defrosting is complete, the four-way valve reverses, and the air conditioning unit switches from cooling mode to heating mode. The outdoor unit's fan turns on, and the outdoor unit's heat exchanger pipe temperature rapidly drops to a constant temperature within seconds. If frosting occurs again after a period of operation, the outdoor unit's refrigerant saturation temperature (pipe temperature) will also drop again. The rate of drop can be used to determine the frosting range.

[0079] When the frosting state is in the slow frosting range, monitor the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe. If the compressor's operating time is greater than the second operating time and the refrigerant temperature in the heat exchanger's inlet pipe is less than the first defrosting temperature, then defrosting begins until the defrosting exit condition is met; otherwise, continue monitoring the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe.

[0080] When the frosting state is in the rapid frosting range, monitor the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe; if the compressor's operating time is greater than the third operating time and the refrigerant temperature in the heat exchanger's inlet pipe is less than the second defrosting temperature, then defrosting begins until the defrosting exit condition is met; otherwise, continue to monitor the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe.

[0081] This invention sets different defrosting judgment conditions for different frosting ranges, so that the heat exchanger of the air conditioning unit can determine whether to start defrosting according to the specific situation, making defrosting more accurate and avoiding defrosting judgment caused by a single factor.

[0082] In one embodiment, the defrosting exit condition for the above-mentioned cases is that the refrigerant temperature in the heat exchanger's inlet pipe is greater than the defrosting exit temperature.

[0083] This invention also protects an air conditioning system including an outdoor heat exchanger, which uses the intelligent defrosting method described above for defrosting.

[0084] In one specific embodiment, the air conditioning system includes, in addition to the outdoor heat exchanger, an indoor heat exchanger, a four-way valve, and in-pipe temperature sensors and defrost temperature sensors.

[0085] like Figure 2 As shown, the outdoor heat exchanger 1 is equipped with a tube-mounted temperature sensor 2 and a defrosting temperature sensor 3.

[0086] The temperature sensor 2 in the pipe is set in the middle of a certain flow path of the heat exchanger (outdoor heat exchanger) of the outdoor unit so as to reflect the condensing temperature or evaporating temperature of the air conditioning system. For example, when the heating mode is running, the temperature sensor 2 in the pipe is set in the middle, and the refrigerant is in a gas-liquid mixed state. The temperature sensor 2 in the pipe detects the refrigerant saturation temperature. The refrigerant saturation temperature of the air conditioning system and the rate of change are used to determine whether the air conditioner is frosting and to execute the corresponding defrosting control.

[0087] In addition to the in-pipe temperature sensor, the present invention also installs a defrost temperature sensor 3 at the refrigerant inlet of the outdoor unit's heat exchanger (outdoor heat exchanger) to detect the refrigerant temperature in the heat exchanger's inlet pipe. Figure 2 In the middle, the defrosting temperature sensor 3 is set on a branch of the shunt 4. Figure 5 The defrosting temperature sensor is installed at the inlet of the distributor, that is, at the main liquid inlet of the outdoor heat exchanger.

[0088] Combination Figure 3 This paper describes the detailed process of a specific embodiment of the present invention.

[0089] In heating mode, after the compressor runs continuously for a period of n minutes, the initial temperature sensor in the pipes begins to monitor the temperature inside the outdoor heat exchanger (the heat exchanger of the outdoor unit) and obtains the refrigerant saturation temperature T. 外管中 And calculate the refrigerant saturation temperature T. 外管中 The time required for a temperature change of 1°C. Where ΔT 外管中 = indicates the current time T 外管中与 T a moment ago 外管中 The difference, i.e., ΔT 外管中 =T 外管中2 -T 外管中1 .

[0090] from Figure 3 As can be seen in the figure, in this embodiment, the present invention divides the refrigerant saturated temperature into four regions: rapid frosting zone, slow frosting zone, pre-frosting zone, and frost-free zone.

[0091] When ΔT 外管中 ≥0 indicates that the evaporation temperature (i.e., the refrigerant saturation temperature) has not decreased, meaning that the air conditioning system has no frost, and in frost-free areas, defrosting is not required, allowing for stable heating operation.

[0092] When ΔT 外管中 <0 indicates that the evaporation temperature has started to decrease; at this point, record T. 外管中 The time required for the temperature to drop by 1°C is used to determine the frosting status of the outdoor unit's heat exchanger.

[0093] Figure 4The specific range of the frosting state of the present invention and the corresponding T are shown. 外管中 The threshold corresponding to the rate of decrease.

[0094] Figure 4 In the table, a and b represent time, b > a > 0, a is the first time, and b is the second time.

[0095] For example, the values ​​of a and b can be a = 5 minutes and b = 10 minutes. This is just an example and does not limit the scope of protection of this invention.

[0096] Figure 4 There are three frosting states: the frosting preparation state, the slow frosting state, and the fast frosting state.

[0097] Figure 3 In the diagram, t1, t2, and t3 represent the compressor operating time thresholds in heating mode, where t1 ≥ t2 ≥ t3. t1 is the first operating time, t2 is the second operating time, and t3 is the third operating time. When T... 外管中 The faster the rate of descent, the earlier defrosting needs to begin, which means the compressor's running time before defrosting begins is shorter.

[0098] For example, t1 = 60 minutes, t2 = 45 minutes, and t3 = 30 minutes. This invention selects the corresponding compressor running time based on different frosting stages (frosting states) so that defrosting can be performed at a more suitable time.

[0099] Figure 3 In the diagram, c, d, and e represent the refrigerant temperature T in the inlet pipe of the outdoor heat exchanger when it is about to enter the defrosting process. 化霜 The specific values ​​of the corresponding thresholds c, d, and e are related to the outdoor ambient temperature. The higher the outdoor ambient temperature, the higher the pipe temperature entering the defrosting process.

[0100] When it is determined that the outdoor unit's heat exchanger (outdoor heat exchanger) is in the frosting preparation zone, if T 外管中 >c, where c is the saturation temperature threshold, such as c = -4℃ or -5℃. The specific value of the saturation temperature threshold is related to the outdoor ambient temperature. The higher the outdoor ambient temperature, the higher the value of c. If c < 0℃ and is 2℃ or more below the outdoor ambient temperature, it means there is no frost or the frost is very thin, and the unit does not need to enter defrosting mode and can continue heating operation. For example, when the outdoor ambient temperature is 2℃, c = -3℃, and when the outdoor ambient temperature is 0℃, c = -5℃, etc.

[0101] When T 外管中If the temperature is less than or equal to c, then the compressor's operating time t is determined. This indicates that the refrigerant saturation temperature is less than the saturation temperature threshold, and the compressor's operating time t needs to be determined. If the compressor's operating time is less than the first operating time, i.e., t < t1, for example, t1 = 60 minutes or t1 = 70 minutes, t < t1 means that frost has just started to form, the frost layer is very thin, and it has little impact on the performance of the air conditioning unit. There is no need to enter defrosting mode, and it can continue to operate in heating mode.

[0102] If the compressor's operating time is greater than or equal to the first operating time, i.e., t≥t1, such as t1=60 minutes, t1=70 minutes, etc., it means that the frost has accumulated to a certain thickness and defrosting can begin.

[0103] If the refrigerant saturation temperature T is detected 外管中 The change in temperature shows a downward trend, and the rate of decrease indicates a slow frosting range. Then, the compressor's operating time t is determined. In heating mode, the compressor's operating time is greater than the second operating time, i.e., t > t2 (e.g., t2 is 45 minutes, 50 minutes, etc.). Furthermore, the refrigerant temperature on the inlet pipe of the outdoor unit's heat exchanger is lower than the first defrosting temperature, i.e., T > t2. 化霜 If the value is less than d, then defrosting begins; otherwise, heating continues. For example, d can be -6℃ or -5℃. The value of d is related to the outdoor ambient temperature; the lower the outdoor ambient temperature, the lower the value of d will be.

[0104] If the refrigerant saturation temperature T is detected 外管中 The change shows a downward trend, and the rate of decrease indicates a rapid frosting range. Then, the compressor's operating time t is determined. In heating mode, the compressor's operating time is greater than the third operating time, i.e., t > t3 (e.g., t3 is 30 minutes, 40 minutes, etc.). Furthermore, the refrigerant temperature on the inlet pipe of the outdoor unit's heat exchanger is lower than the second defrosting temperature, i.e., T > t3. 化霜 If the value is less than e, then defrosting begins; otherwise, heating continues. For example, e can be -6℃ or -7℃. The value of e is related to the outdoor ambient temperature; the lower the outdoor ambient temperature, the lower the value of e.

[0105] After the above-mentioned control enters the defrost state, the defrost temperature sensor continues to monitor the refrigerant temperature T on the inlet pipe of the outdoor unit's heat exchanger. 化霜， When T 化霜 >f, where f is the defrost exit temperature. For example, defrost will exit when f = 10℃ or f = 12℃, and the unit will resume heating mode operation. After the compressor has been running for a period of time, the refrigerant saturation temperature of the outdoor unit's heat exchanger will be monitored, and the unit will return to step 1 to start the next round of defrost determination.

[0106] Before determining the refrigerant temperature requirements of the outdoor unit's heat exchanger inlet pipe, the outdoor ambient temperature can be checked. Based on the ambient temperature, the corresponding defrost temperature threshold for the outdoor unit's heat exchanger inlet pipe is selected. This defrost temperature threshold refers to the first defrost temperature and the second defrost temperature. Specifically, during the slow frosting phase, the outdoor ambient temperature is checked before determining the refrigerant temperature of the outdoor unit's heat exchanger inlet pipe, and the first defrost temperature value is determined accordingly. Similarly, during the rapid frosting phase, the outdoor ambient temperature is checked before determining the refrigerant temperature of the outdoor unit's heat exchanger inlet pipe, and the second defrost temperature value is determined accordingly. This ensures that each different frosting state has more suitable defrost determination conditions.

[0107] The lower the outdoor ambient temperature, the higher the corresponding T 化霜 The lower the temperature, the lower the temperature will be during the heating process when the heat exchanger is not frosted. 化霜 It will be about 2°C to 5°C lower than the ambient temperature. For example, at an ambient temperature of 3°C, even without frost, T 化霜 It might only reach -2℃; when the ambient temperature is -10℃, it won't frost, and the defrosting temperature sensor will only reach approximately -12℃. If it frosts, then T... 化霜 It is definitely below 0℃, and more than 2℃ below the outdoor ambient temperature.

[0108] It should be noted that the condensate produced by the outdoor unit's heat exchanger during evaporation will frost over at low temperatures. The amount of condensate is related to air humidity; higher humidity results in more condensate, making frost formation more likely at low temperatures. The faster the frost forms, the faster the system's low pressure drops, indicating a decrease in temperature. 外管中 The greater the rate of decline, the more accurate the present invention is based on T. 外管中 The rate of descent is used to classify the frosting state. If T 外管中 Even if the temperature remains above 0°C, frost will not form. If the humidity is zero, no condensation will occur regardless of the ambient temperature, and frost will not form. If the humidity is very low and the pipe temperature is below 0°C, frost may not form, or only very little, which will not affect the unit's heat exchange. In this case, T... 外管中 It will not decrease or the rate of decrease is very slow, therefore this invention uses T 外管中 The division of the area takes into full consideration the air humidity and the corresponding outdoor temperature.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An intelligent defrosting method, characterized in that, include: Step 1: Monitor the refrigerant saturation temperature of the heat exchanger; Step 2: Determine whether the heat exchanger is frosted and the frosting state when frosting occurs by observing the change in the refrigerant saturation temperature. Specifically, the change in the refrigerant saturation temperature refers to the time taken for the refrigerant saturation temperature to decrease by one unit temperature. When the time taken for the refrigerant saturation temperature to decrease by one unit temperature is greater than zero and less than or equal to a first time, the frosting state of the heat exchanger is in the rapid frosting range. When the time taken for the refrigerant saturation temperature to decrease by one unit temperature is greater than the first time and less than or equal to a second time, the frosting state of the heat exchanger is in the slow frosting range. When the time taken for the refrigerant saturated temperature to drop by one unit temperature is greater than the second time, the heat exchanger is in the frosting state of the preparation for frosting interval. Step 3: Defrost using different defrosting criteria under different frosting conditions, including: when the frosting condition is in the slow frosting range, monitoring the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe. If the compressor's operating time exceeds the second operating time, and the refrigerant temperature in the heat exchanger's inlet pipe is lower than the first defrosting temperature, then defrosting begins until the defrosting exit condition is met; otherwise, the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe continue to be monitored.

2. The intelligent defrosting method as described in claim 1, characterized in that, The refrigerant saturation temperature of the heat exchanger is monitored by installing at least one temperature sensor in the middle of the branch pipe of the heat exchanger.

3. The intelligent defrosting method as described in claim 1, characterized in that, Determining whether the heat exchanger is frosted by observing the change in the refrigerant's saturation temperature includes: If the refrigerant saturation temperature does not decrease, it is determined that the heat exchanger is not frosted.

4. The intelligent defrosting method as described in claim 1, characterized in that, Determining whether the heat exchanger is frosted by observing the change in the refrigerant's saturation temperature includes: When the refrigerant saturation temperature drops, it is determined that the heat exchanger is frosted.

5. The intelligent defrosting method as described in claim 1, characterized in that, The unit temperature is 1℃.

6. The intelligent defrosting method as described in claim 1, characterized in that, Defrost using different defrosting criteria for different frosting states, including: When the frosting state is in the frosting preparation interval, determine whether the refrigerant saturation temperature is greater than the saturation temperature threshold. If it is greater, return to step 1. If it is less than or equal to, determine whether the compressor's running time has reached the first running time. If it has, start defrosting until the defrosting exit condition is met. If it has not been met, return to step 1.

7. The intelligent defrosting method as described in claim 1, characterized in that, Defrost using different defrosting criteria for different frosting states, including: When the frosting state is in the rapid frosting range, monitor the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe; If the compressor's operating time exceeds the third operating time and the refrigerant temperature in the heat exchanger's inlet pipe is lower than the second defrost temperature, defrosting begins until the defrost exit condition is met; otherwise, the compressor's operating time and the refrigerant temperature in the heat exchanger's inlet pipe continue to be monitored.

8. The intelligent defrosting method as described in claim 6 or 7, characterized in that, The defrosting exit condition is that the refrigerant temperature in the inlet pipe of the heat exchanger is greater than the defrosting exit temperature.

9. The intelligent defrosting method as described in claim 1 or 7, characterized in that, Before determining the refrigerant temperature in the inlet pipe of the heat exchanger, the outdoor ambient temperature is detected, and the corresponding defrosting temperature threshold value is selected based on the outdoor ambient temperature value.

10. An air conditioning system, characterized in that, It includes an outdoor heat exchanger, which is defrosted using the intelligent defrosting method as described in any one of claims 1 to 9.

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