Air conditioner air-cooled unit and method for controlling frost thereof

Abstract

The application discloses a kind of air conditioner air-cooled unit's frost control method, comprising: after the unit is started for a period of time, calculate the heating energy efficiency ratio drop amplitude;When the heating energy efficiency ratio drop amplitude is always greater than the preset value in a certain time, the unit continues heating while starting frost suppression mode and defrost preparation mode;During the process of frost suppression mode and defrost preparation mode, calculate the heating energy efficiency ratio drop amplitude, according to the heating energy efficiency ratio drop amplitude, switch the operation mode of unit, or select the corresponding judgment condition to switch the operation mode of unit again.The application combines the heating energy efficiency ratio drop amplitude with the frost suppression mode, and starts the defrost preparation mode at the same time when the frost suppression mode is started, so that the effect of accurate frost control and energy saving can be achieved.

Description

Technical Field

[0001] This invention relates to the technical field of defrosting control in air conditioning systems, and more particularly to a defrosting control method for air-cooled air conditioning units. Background Technology

[0002] There are many defrosting methods for existing air conditioning systems.

[0003] To address the issue of continuous heating during defrosting, some existing technologies employ a solution that involves adding a defrosting pipeline to the air conditioning unit. This pipeline has its inlet located on the connection between the four-way valve and the indoor unit, and its outlet located on the liquid inlet main of the outdoor unit. A defrosting solenoid valve is installed on the defrosting pipeline and is used to open when the air conditioning defrosting system performs defrosting operations, so that the unit can perform defrosting while maintaining normal heating.

[0004] Regarding how the defrost solenoid valve is triggered to open, the existing technology presets defrost conditions. The defrost solenoid valve is used to open when the operating parameters of the air conditioning defrost system meet the defrost conditions. These defrost conditions can include at least one of the following: defrost temperature < preset temperature + ambient temperature correction value, and lasting for a first preset duration; system low pressure < preset low pressure + ambient temperature correction value, and lasting for a first preset duration; the difference between the system low pressure of any operating unit in the air conditioning defrost system and the system low pressure of other operating units is within a preset difference range; the deviation between the system low pressure and the low pressure data in the big data platform < preset low pressure deviation; and the deviation between the defrost temperature and the temperature data in the big data platform < preset temperature deviation. The decrease in system low pressure within a second preset duration exceeds a first preset value, and the decrease in defrost temperature within a second preset duration exceeds a second preset value. The aforementioned defrost temperature is the temperature value monitored by a defrost temperature sensor located on the heat exchanger branch of the outdoor unit. The aforementioned system low pressure is the pressure value monitored by a low-pressure sensor located on the inlet pipe of the vapor-liquid separator. The existing technology adds a defrosting pipeline to the original heat pump system. A defrosting solenoid valve is added to the defrosting pipeline to control the flow of refrigerant in order to defrost the outdoor unit.

[0005] While the existing technology achieves the goal of performing defrosting operations when defrosting is needed while simultaneously maintaining continuous heating, thereby shortening the defrosting cycle, extending the unit's heating time, and improving energy efficiency, it suffers from several drawbacks. Because defrosting occurs simultaneously with heating, the defrosting process is not thorough, and the subsequent shutdown for defrosting is relatively lengthy. Furthermore, when this existing technology is applied to large commercial air conditioning units, accurate defrosting timing is difficult to determine.

[0006] Taking the defrosting control of a common air-cooled heat pump unit as an example, the existing defrosting control technology determines whether to enter the defrosting mode by detecting the pressure and temperature parameters of the outdoor heat exchanger. This method requires a lot of detection components and is affected by the outdoor environment. Dust and impurities in the outdoor environment can easily adhere to the surface of the fins, affecting the heat exchange of the fins. Due to the presence of the impurity layer, the low pressure is relatively low. For units that rely on low pressure detection to control the entry into the defrosting mode, it is very easy to cause misjudgment, which can easily lead to defrosting mode failure or incorrect judgment of defrosting conditions, resulting in defrosting without frost. Both of these situations will greatly affect the heating performance and the user's comfort experience.

[0007] Therefore, how to provide a defrosting method that is both energy-efficient and highly effective is a technical problem to be solved. Summary of the Invention

[0008] To address the problems caused by using COP alone to enter defrost mode in existing technologies, as well as the technical issues of insufficient efficiency in entering defrost mode, this invention proposes an air-cooled air conditioning system and its defrosting control method.

[0009] The defrosting method for air-cooled air conditioning units proposed in this invention includes: After the unit has been running for a period of time, calculate the decrease in heating efficiency ratio; If the decrease in heating efficiency ratio is greater than the preset value for a certain period of time, the unit will continue to heat while activating the defrost suppression mode and defrost preparation mode. During the defrost suppression mode and defrost preparation mode, the decrease in heating efficiency ratio is calculated. Based on the decrease in heating efficiency ratio, the unit's operating mode is switched, or the corresponding judgment conditions are selected before switching the unit's operating mode.

[0010] Furthermore, if the decrease in heating efficiency ratio is consistently less than the preset value within a certain period of time during the defrost mode and defrost preparation mode, the defrost mode and defrost preparation mode will be turned off, and the system will enter the normal heating mode.

[0011] Furthermore, if the heating efficiency ratio drops more than the preset value during the defrosting mode and defrosting preparation mode, the defrosting mode and defrosting preparation mode will be maintained, and the defrosting conditions will be monitored in real time and the running time of the defrosting mode will be counted. When the defrosting conditions and / or the defrosting mode run time is greater than or equal to the preset time, if the defrosting preparation is complete at this time, heating will be paused and defrosting will begin.

[0012] Furthermore, if the defrosting conditions and / or the duration of the defrosting mode are met is greater than or equal to the preset duration, and if the defrosting preparation is still in progress, then wait for the defrosting preparation to be completed before pausing heating and starting defrosting.

[0013] Furthermore, the defrosting monitoring conditions include: Monitor whether the decrease in heating efficiency ratio is greater than the preset value; Monitor the inhalation pressure for θ seconds to ensure that the inhalation pressure is less than or equal to the set value P. Monitor whether the cumulative running time of the compressor meets the requirement that the cumulative running time t > the defrosting interval setting time t1; Monitor whether the defrost temperature sensor meets the requirement that the defrost temperature detected for 60 consecutive seconds is less than or equal to the defrost start setting temperature T1. Whether the system differential pressure meets the requirement that the system differential pressure is greater than the target differential pressure ΔP for the four-way valve switching; Monitor whether the outlet water temperature of the unit meets the requirement that the outlet water temperature is greater than the minimum tolerable outlet water temperature for defrosting, T2; Monitor whether the compressor of the unit has been running for more than N minutes.

[0014] Furthermore, the defrosting mode includes the step of directly introducing the refrigerant from the compressor exhaust port of the unit into the finned refrigerant pipe of the evaporator.

[0015] Furthermore, the defrosting preparation mode includes the following steps: The compressor will be loaded to full capacity within the preset loading time. The main throttling element opens to the target opening degree X; Adjust the outlet water temperature to the defrosting preparation target water temperature T. m .

[0016] Furthermore, the decrease in heating efficiency ratio is obtained by subtracting the current time from the COP after the previous defrost and entering the current heating period m minutes later, and dividing the result by the COP after the previous defrost and entering the current heating period m minutes later.

[0017] Furthermore, the COP is calculated using the formula COP=α pressure ratio + β evaporation temperature - γ inlet water temperature + δ inlet and outlet water temperature difference + η.

[0018] The air-cooled air conditioning unit proposed in this invention includes a controller, which adopts the defrosting method of the air-cooled air conditioning unit described above when the unit is in heating mode.

[0019] Furthermore, the unit also includes: The main circulation path includes a compressor, an air-side heat exchanger, a water-side heat exchanger, a main throttling element, and a four-way valve; A bypass branch is provided with a bypass valve, and one end of the bypass branch is connected to the refrigerant inlet of the water-side heat exchanger, while the other end is connected to the finned refrigerant pipe of the air-side heat exchanger.

[0020] This invention determines whether a unit needs to enter defrost mode by detecting changes in the unit's Coefficient of Performance (COP). When the ΔCOP remains within a preset range for a period of time, defrost mode is activated. The advantage of defrost mode is that it controls frost formation and defrosts to a certain extent without shutting down the unit. This mode extends the unit's operating time, eliminating the need to immediately stop for defrosting when frost forms. Simultaneously, this invention activates a defrost preparation mode at the same time as the defrost mode, thus enabling more efficient defrosting. This invention can determine whether and when to activate defrost mode based on the defrost mode's operating time and the change in ΔCOP after activation, making defrost determination more accurate and effectively solving the problems of "defrosting without frost, not defrosting when frost is present, and inaccurate defrost timing" in traditional air-cooled heat pump units. Attached Figure Description

[0021] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein: Figure 1 This is an overall flowchart of an embodiment of the present invention.

[0022] Figure 2 This is a refrigerant flow diagram of a cooling mode according to an embodiment of the present invention.

[0023] Figure 3 This is a refrigerant flow diagram of a heating mode according to an embodiment of the present invention.

[0024] Figure 4 This is a refrigerant flow diagram of the defrosting mode according to an embodiment of the present invention.

[0025] Figure 5 This is a flowchart of the defrosting process according to an embodiment of the present invention.

[0026] Figure 6 This is a flowchart of the defrosting determination process according to an embodiment of the present invention.

[0027] Figure 7 This is a flowchart of the defrosting determination process according to another embodiment of the present invention.

[0028] Figure 8 This is a flowchart of the defrosting determination process according to the third embodiment of the present invention.

[0029] Figure 9 This is an overall flowchart of a specific embodiment of the present invention.

[0030] Figure 10 This is a parameter description table of a specific embodiment of the present invention. Attached Figure Description

[0032] 1. Compressor; 2. Four-way valve; 3. Fins; 4. Fan; 5. Main throttling element; 6. Water-side heat exchanger; 7. Bypass valve. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] like Figure 1 As shown, a typical embodiment of the air-cooled air conditioning unit of the present invention includes a main circulation path and a bypass branch.

[0036] The main circulation path includes a compressor 1, an air-side heat exchanger, a water-side heat exchanger 6, a main throttling element 5, and a four-way valve 2. The air-side heat exchanger includes fins 3 and a fan 4.

[0037] In one embodiment, the main throttling element 5 is an electronic expansion valve.

[0038] A bypass valve is installed on the bypass branch. One end of the bypass branch is connected to the refrigerant inlet of the water-side heat exchanger, and the other end is connected to the finned refrigerant pipe of the air-side heat exchanger.

[0039] In one embodiment, the bypass valve is a solenoid valve.

[0040] like Figure 2 As shown, when the unit is operating in normal cooling mode, the refrigerant enters the four-way valve 2 from the exhaust side of the compressor 1, then passes through the air-side heat exchanger, then through the main throttling element 5, then through the water-side heat exchanger 6, and finally returns to the suction side of the compressor.

[0041] In conventional refrigeration mode, the refrigerant passes through the following sequence: compressor 1 → four-way valve 2 → air-side heat exchanger (fins 3 and fan 4) → main throttling element 5 → water-side heat exchanger 6.

[0042] like Figure 3As shown, when the unit is operating in normal heating mode, the refrigerant enters the four-way valve 2 from the exhaust side of the compressor 1, then passes through the water-side heat exchanger 6, then through the main throttling element 5, then through the air-side heat exchanger, and finally returns to the suction side of the compressor.

[0043] In the conventional heating mode, the refrigerant passes through the compressor 1 → four-way valve 2 → water-side heat exchanger 6 → main throttling element 5 (electronic expansion valve) → air-side heat exchanger (fins 3 and fan 4).

[0044] like Figure 4 As shown, when the unit continues heating while operating in defrost mode, the refrigerant enters the four-way valve 2 from the compressor's discharge side, then passes through the water-side heat exchanger 6, the main throttling element 5, the air-side heat exchanger, and finally returns to the compressor's suction side. Another route passes through a bypass valve and directly into the finned refrigerant pipes of the air-side heat exchanger, thus suppressing frost formation on the air-side heat exchanger. If a thin layer of frost is present on the air-side heat exchanger, it can be removed directly using defrost mode. Furthermore, the heating mode continues to operate during this time, without affecting user experience.

[0045] In defrost mode, the refrigerant flow sequence includes two routes: one is compressor 1 → four-way valve 2 → water-side heat exchanger 6 → main throttling element 5 → air-side heat exchanger (fins 3 and fan 4). The other is compressor 1 → four-way valve 2 → bypass valve 7 → air-side heat exchanger (fins 3 and fan 4).

[0046] The heating process of this invention is described in detail below. High-temperature, high-pressure refrigerant gas discharged from compressor 1 enters the water-side heat exchanger 6 through ports D and E of the four-way valve 2 to exchange heat with water and produce hot water. Here, the high-temperature, high-pressure refrigerant gas is condensed into a high-pressure, medium-temperature refrigerant liquid. After being throttled by the main throttling element 5, it becomes a low-temperature, low-pressure refrigerant that enters the fins 3 and, under the action of the fixed-frequency fan 4, enhances heat exchange with the air, evaporating into a low-temperature, low-pressure superheated gas. This gas then returns to compressor 1 through ports C and S of the four-way valve, completing the heating refrigerant cycle. During this process, the refrigerant evaporation and heat exchange at the fins lowers the fin surface temperature. Water vapor in the air comes into contact with the low-temperature fin surface, causing frost to form. As the heating cycle continues, the frost layer gradually thickens.

[0047] In order to achieve defrosting control of air-cooled air conditioning units in the above process, this invention proposes a defrosting control method for air-cooled air conditioning units.

[0048] like Figure 5 As shown, in one embodiment, the defrosting method for an air-cooled air conditioning unit of the present invention includes the following steps.

[0049] After the unit has been running for a period of time, calculate the decrease in heating efficiency ratio; If the decrease in heating efficiency ratio is greater than the preset value for a certain period of time, the unit will continue to heat while activating the defrost suppression mode and defrost preparation mode. During the defrosting mode and defrosting preparation mode, the decrease in heating efficiency ratio is calculated. Based on the decrease in heating efficiency ratio, the operating mode of the air-cooled unit is switched, or the corresponding judgment conditions are selected before switching the operating mode of the air-cooled unit.

[0050] As described above, the operating modes of the unit of this invention include: conventional cooling mode, conventional heating mode, defrosting mode, defrosting preparation mode, and defrosting mode. Since this invention discusses defrosting control methods, the conventional cooling mode will not be discussed in detail. The defrosting mode and defrosting preparation mode of this invention are two modes that are activated simultaneously. Because the unit continues to heat when the defrosting mode is activated, the defrosting mode is not a defrosting mode, but merely slows down the frosting process or removes the thin layer of frost that has already condensed. If the unit's current frosting rate is fast or other defrosting modes cannot effectively suppress frost, since this invention has also activated the defrosting preparation mode, it can quickly enter the defrosting mode, thereby defrosting in a timely and effective manner.

[0051] In one specific embodiment, if the decrease in heating efficiency ratio is consistently less than a preset value within a certain period of time during the defrosting mode and defrosting preparation mode, the defrosting mode and defrosting preparation mode are turned off, and the system enters the normal heating mode.

[0052] If the unit's current frosting speed is slow, or the frost layer is thin, the frosting mode effectively controls the degree of frosting on the air-side heat exchanger. When the decrease in heating energy ratio is reduced to less than or equal to the preset value, the unit can switch to conventional heating mode, thus effectively solving the problems of "frost-free defrosting, frost-free operation, and inaccurate defrosting time" in traditional large-scale air-cooled units.

[0053] Another feature of this invention is that it uses the decrease in heating efficiency ratio to detect whether defrosting mode has been entered. Existing technologies usually use COP to detect whether defrosting mode has been entered. If defrosting is determined solely by the decrease in COP, it will fall into the misconception of defrosting without frost or inaccurate defrosting, because there are many reasons for the decrease in COP, such as obstructed refrigerant circulation, insufficient refrigerant quantity, insufficient capacity, failure of the economizer to function, lack of subcooling of the condenser, frost on the condenser, and so on. Defrosting is only one of the many reasons. It is only because the decrease in COP leads to inaccurate defrosting control that the defrosting mode has been entered. Therefore, this invention provides a more precise defrosting control method.

[0054] like Figure 6As shown, in one specific embodiment, if the heating energy efficiency ratio drops more than a preset value during the defrosting mode and defrosting preparation mode, the defrosting mode and defrosting preparation mode are maintained, and the defrosting conditions are monitored in real time and the running time of the defrosting mode is counted. When the defrosting conditions are met, if defrosting preparation is complete, heating will be paused and defrosting will begin.

[0055] In this embodiment, the present invention continuously monitors the decrease in heating efficiency ratio during the defrosting mode. If the decrease in heating efficiency ratio is consistently greater than a preset value, the defrosting mode can be entered based on the defrosting conditions. Since defrosting preparations have already been completed, the defrosting mode can be entered quickly. Compared to existing technologies that require further control of the compressor and throttling components after judgment before entering the defrosting process, the defrosting of the present invention is more efficient.

[0056] like Figure 7 As shown, in one specific embodiment, if the heating energy efficiency ratio drops more than a preset value during the defrosting mode and defrosting preparation mode, the defrosting mode and defrosting preparation mode are maintained, and the defrosting conditions are monitored in real time and the running time of the defrosting mode is counted. When the duration of the defrost mode is greater than or equal to the preset duration, if defrosting is ready at this time, heating will be paused and defrosting will begin.

[0057] In this embodiment, the present invention continuously monitors the decrease in heating efficiency ratio during the defrost mode. If the decrease in heating efficiency ratio consistently exceeds a preset value, the defrost mode duration can be used to determine whether to enter defrost mode. Because defrost preparation is performed simultaneously, defrost mode can be entered quickly. Compared to existing technologies that require further control of the compressor and throttling components after initial assessment before entering the defrost process, the defrost process of the present invention is more efficient.

[0058] like Figure 8 As shown, in one specific embodiment, if the heating energy efficiency ratio drops more than a preset value during the defrosting mode and defrosting preparation mode, the defrosting mode and defrosting preparation mode are maintained, and the defrosting conditions are monitored in real time and the running time of the defrosting mode is counted. When the defrosting conditions are met and the duration of the defrosting mode is greater than or equal to the preset duration, if the defrosting preparation is complete at this time, heating will be paused and defrosting will begin.

[0059] In this embodiment, the present invention continuously monitors the decrease in heating efficiency ratio during the defrost mode. If the decrease in heating efficiency ratio is consistently greater than a preset value, and the defrost mode running time is also greater than or equal to a preset time while meeting the defrost conditions, then the defrost mode must be activated as soon as possible. Because defrost preparation is carried out simultaneously, the defrost mode can be entered quickly. Compared to the prior art, which requires further control of the compressor and throttling components after judgment before entering the defrost process, the defrost of the present invention is more efficient.

[0060] In a supplementary embodiment, if the runtime of the defrosting condition and / or the defrosting mode is greater than or equal to a preset duration, and if defrosting preparation is still in progress, then wait for defrosting preparation to complete before pausing heating and starting defrosting. Allowing defrosting preparation to be completed before starting defrosting ensures effective defrosting.

[0061] In the above embodiments, the defrosting conditions are monitored in the following ways.

[0062] Monitor whether the decrease in heating efficiency ratio is greater than the preset value; Monitor the inhalation pressure for θ seconds to ensure that the inhalation pressure is less than or equal to the set value P. Monitor whether the cumulative running time of the compressor meets the requirement that the cumulative running time t > the defrosting interval setting time t1; Monitor whether the defrost temperature sensor meets the requirement that the defrost temperature detected for 60 consecutive seconds is less than or equal to the defrost start setting temperature T1. Whether the system differential pressure meets the requirement that the system differential pressure is greater than the target differential pressure ΔP for the four-way valve switching; Monitor whether the outlet water temperature of the air conditioning unit meets the requirement that the outlet water temperature is greater than the minimum tolerable outlet water temperature for defrosting, T2. Monitor whether the compressor of the air conditioning unit has been running for more than N minutes.

[0063] In one specific embodiment, in the defrost mode, the refrigerant at the exhaust port of the air conditioning unit's compressor is directly introduced into the refrigerant pipe of the evaporator fins, thereby melting the thinner frost layer on the fins.

[0064] In one specific embodiment, the defrosting preparation mode of the present invention includes the following steps, and the steps do not have a significant order.

[0065] The compressor will be loaded to full capacity within the preset loading time. The main throttling element opens to the target opening degree X; Adjust the outlet water temperature to the defrosting preparation target water temperature T. m .

[0066] In one specific embodiment, the decrease in heating efficiency ratio of the present invention is obtained by subtracting the current time from the COP after the previous defrost ended and entering the current heating m minutes later, and dividing the COP after the previous defrost ended and entering the current heating m minutes later.

[0067] In existing technologies, COP is usually obtained by dividing capacity by power, i.e., COP = capacity / power. COP is an important indicator for measuring the operating performance of a unit. When the unit is operating normally, there is no frost on the fins, the fan runs normally, and the COP can be maintained at a satisfactory threshold. However, after frost appears on the fins on the condenser side of the unit, the frost layer on the outer layer of the fins makes it difficult for air to enter, resulting in insufficient heat exchange on the condenser side and no subcooling, which leads to a decrease in the unit's cooling capacity. At the same time, if the heat exchange on the condenser side is insufficient, the unit will increase the fan frequency to meet the heat exchange demand. However, as the frost layer becomes thicker and thicker, even increasing the fan frequency will not help, resulting in low capacity, high power, and a significant decrease in the unit's COP.

[0068] Although COP can effectively reflect the status of a unit, it is very difficult to accurately measure the actual cooling or heating capacity of large air-cooled units because power meters and devices for testing unit capacity cannot be equipped at large engineering sites. Therefore, this invention provides a method for calculating COP. COP is calculated using the formula COP = α pressure ratio + β evaporation temperature - γ inlet water temperature + δ inlet and outlet water temperature difference + η. The parameters used in this formula can be easily measured at the engineering site, thus enabling accurate calculation of the corresponding COP. The coefficients α, β, γ, δ, and η used in this formula can be obtained by fitting relevant data.

[0069] The defrosting method of this invention can detect slight frost on the fins by calculating the decrease in heating efficiency ratio in the early stage of monitoring and implement defrosting control to maintain the unit's capacity and performance for a period of time. When the defrosting control cannot meet the requirements, the defrosting mode is switched immediately.

[0070] Figure 9 A specific embodiment of the present invention is shown, which will be described in detail below.

[0071] After the unit starts heating, it will run for an initial period of M hours. During this M-hour period, defrosting condition detection will not be performed to avoid the unit system being unstable during initial startup, which could lead to incorrect identification and triggering the defrosting process.

[0072] After a duration of M, the unit enters the anti-frost detection step to detect the decrease in heating efficiency ratio ΔCOP.

[0073] This test is the initial step in inhibiting defrosting and continuously monitors the decrease in heating efficiency ratio (ΔCOP).

[0074] When the heating efficiency ratio decreases by ΔCOP within time period A, the decrease in COP is always greater than that of COP. x1 -1 activates the anti-frost mode and simultaneously enters the defrosting preparation mode.

[0075] After the defrost mode is activated, open the bypass valve 7. Simultaneously monitor the defrost conditions in real time.

[0076] After activating the anti-frost mode, clear the △COP monitoring data and re-monitor (this mode is designed to slow down the frosting rate and melt the initial frosting layer to a certain extent without affecting the unit's operation).

[0077] During the defrost mode, when the heating efficiency ratio (COP) decrease (ΔCOP) was consistently less than the COP within time period A, the monitoring showed that the COP was not affected. x1 -1 indicates that the unit's energy efficiency has recovered. The defrosting mode is turned off, the bypass valve 7 is turned off, and the defrosting preparation mode is turned off.

[0078] During the defrost mode, if the decrease in heating efficiency ratio (ΔCOP) is greater than the preset value (COP), x1 -1, this preset value is also called the defrosting efficiency ratio preset value, which maintains the defrosting mode and monitors the defrosting conditions in real time.

[0079] If the defrost mode has been running for S minutes and the monitored value of the heating efficiency ratio decrease ΔCOP has not reached the condition for turning off the defrost mode, then the defrost mode will be turned on directly, the defrost mode will be turned off, and the bypass valve will be closed.

[0080] The main function of activating the defrost preparation mode in this embodiment is to switch the unit into a defrost preparation state. This involves rapidly loading the compressor to full load; opening the main throttling element to the target opening degree X; and automatically adjusting the outlet water temperature to the defrost preparation target water temperature T. m .

[0081] The defrosting conditions monitored in this embodiment include the following aspects.

[0082] ① Monitor whether the condition △COP>COP is met. x1 -1; ② Continuously check for θ seconds whether the inhalation pressure ≤ P set value; ③ Monitor whether the cumulative running time (compressor start time) t of the compressor is greater than the defrost interval setting time t1; ④ Monitor whether the defrost temperature detected by the defrost temperature sensor for 60 consecutive seconds is less than or equal to the defrost start setting temperature T1; ⑤ Monitor whether the system pressure difference is greater than the target pressure difference ΔP for the four-way valve reversal (the system pressure difference is the value of the compressor's high pressure minus the low pressure). ⑥ Monitor the air conditioner outlet water temperature to be greater than the minimum tolerable outlet water temperature for defrosting, T2; ⑦ Monitor whether the compressor has been running for more than N minutes.

[0083] If all the above defrosting conditions are met, and the unit's outlet water temperature is greater than or equal to the target defrosting water temperature T, then... m Then the defrosting mode will be activated.

[0084] If the monitored unit does not meet the defrosting conditions and the defrosting mode has been turned off, it means that the unit has returned to normal operation and is in a frost-free state, and the defrosting preparation state is turned off.

[0085] Enable anti-frost mode and monitor the defrost exit conditions in real time. The exit conditions are as follows.

[0086] (1) Monitor whether the defrosting time T is met. h > Defrosting duration setting T t .

[0087] (2) Monitor whether the defrosting temperature of the continuous f-second detection system is greater than the defrosting end set temperature T. j .

[0088] (3) Monitor whether the high pressure continuous Y seconds > defrost exit pressure F is met.

[0089] Once any one of the above three conditions is met, the defrosting mode will be exited and the unit will return to the normal heating mode. After a time of M, the unit will operate stably and enter the defrosting condition monitoring mode.

[0090] This invention determines whether the air-cooled heat pump unit needs defrosting by detecting changes in its COP. It comprehensively controls the switching between heating and defrosting states by analyzing the unit's frosting status and its impact on unit performance. This effectively solves the problems of traditional air-cooled heat pump units, such as "defrosting without frost, not defrosting when there is frost, and inaccurate defrosting time."

[0091] The above description is only 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. A defrosting method for an air-cooled air conditioning unit, characterized in that, include: After the unit has been running for a period of time, calculate the decrease in heating efficiency ratio; If the decrease in heating efficiency ratio is greater than the preset value for a certain period of time, the unit will continue to heat while starting the defrost mode and defrost preparation mode. During the defrost mode and defrost preparation mode, the decrease in heating efficiency ratio is calculated. Based on the decrease in heating efficiency ratio, the unit's operating mode is switched, or the corresponding judgment conditions are selected before switching the unit's operating mode. During the defrost mode and defrost preparation mode, if the heating efficiency ratio drops more than the preset value, the defrost mode and defrost preparation mode will be maintained, and the defrost conditions will be monitored in real time and the running time of the defrost mode will be counted. The defrost mode includes the following steps: the refrigerant at the exhaust port of the unit's compressor is directly introduced into the finned refrigerant pipe of the evaporator. The drop in heating efficiency ratio is obtained by subtracting the current time's COP from the COP after m minutes of heating following the previous defrost, and dividing the COP after m minutes of heating following the previous defrost. COP is the heating efficiency ratio. When the defrosting conditions and / or the defrosting mode run time is greater than or equal to the preset time, if the defrosting preparation is complete at this time, heating will be paused and defrosting will begin. If defrosting preparation is still in progress, wait until defrosting is complete before pausing heating and starting defrosting.

2. The defrosting method for an air-cooled air conditioning unit as described in claim 1, characterized in that, If the decrease in heating efficiency ratio is consistently less than the preset value within a certain period of time during the defrost mode and defrost preparation mode, the defrost mode and defrost preparation mode will be turned off and the normal heating mode will be entered.

3. The defrosting method for an air-cooled air conditioning unit as described in claim 1, characterized in that, The defrosting monitoring conditions include: Monitor whether the decrease in heating efficiency ratio is greater than the preset value; Monitor the inhalation pressure for θ seconds to ensure that the inhalation pressure is less than or equal to the set value P. Monitor whether the cumulative running time of the compressor meets the requirement that the cumulative running time t > the defrosting interval setting time t1; Monitor whether the defrost temperature sensor meets the requirement that the defrost temperature detected for 60 consecutive seconds is less than or equal to the defrost start setting temperature T1. Whether the system differential pressure meets the requirement that the system differential pressure is greater than the target differential pressure ΔP for the four-way valve switching; Monitor whether the outlet water temperature of the unit meets the requirement that the outlet water temperature is greater than the minimum tolerable outlet water temperature for defrosting, T2; Monitor whether the compressor of the unit has been running for more than N minutes.

4. The defrosting method for an air-cooled air conditioning unit as described in claim 1, characterized in that, The defrosting preparation mode includes the following steps: The compressor will be loaded to full capacity within the preset loading time. The main throttling element opens to the target opening degree X; Adjust the outlet water temperature to the defrosting preparation target water temperature T. m .

5. The defrosting method for an air-cooled air conditioning unit as described in claim 1, characterized in that, The COP is calculated using the formula COP=α pressure ratio + β evaporation temperature - γ inlet water temperature + δ inlet and outlet water temperature difference + η, where α, β, γ, δ, and η are coefficients.

6. An air-cooled air conditioning unit, comprising a controller, characterized in that, The controller employs the defrosting method for air-cooled air conditioning units as described in any one of claims 1 to 5 when the unit is in heating mode.

7. The air-cooled air conditioning unit as described in claim 6, characterized in that, The unit also includes: The main circulation path includes a compressor, an air-side heat exchanger, a water-side heat exchanger, a main throttling element, and a four-way valve; A bypass branch is provided with a bypass valve, and one end of the bypass branch is connected to the refrigerant inlet of the water-side heat exchanger, while the other end is connected to the finned refrigerant pipe of the air-side heat exchanger.

Images