Defrosting operation method of heat pump

Abstract

The defrosting operation method of the heat pump comprises the heat pump and comprises the following steps during operation: step 1, electrifying the heat pump, and entering step 2; 2, a central controller of the heat pump presets the initial continuous heating time th of the heat pump, the initial defrosting time td, the coil pipe temperature initial threshold value Tp0 when defrosting is quitted, the coil pipe temperature threshold value Tp1 when a defrosting preheating stage is quitted, the coil pipe temperature threshold value Tp2 when a defrosting stable stage is quitted, the first operation frequency Fa of a compressor in the defrosting preheating stage, and the second operation frequency Fb of a compressor in the defrosting preheating stage; the second operation frequency Ft of the compressor in the defrosting stabilization stage and the third operation frequency Fc of the compressor in the heating and drying stage enter the third step, the value range of th is 20-180 minutes, the value range of td is 3-20 minutes, the value range of Tp0 is 10-60 DEG C, and the value range of Tp1 is-10-5 DEG C. The method has the characteristics of short defrosting time and small energy consumption loss.

Description

Technical Field

[0001] This invention relates to a defrosting operation method for a heat pump. Background Technology

[0002] Common problems with heat pump defrosting include: 1) Misjudgment of defrosting timing: Relying on fixed temperature thresholds or time to determine defrosting needs and exit the defrosting program can easily lead to energy-wasting, frost-free defrosting, or incomplete defrosting resulting in a sudden drop in heating efficiency; 2) Crude defrosting process: Using fixed compressor operating frequency and electronic expansion valve opening during defrosting can easily cause excessively long defrosting times, poor heat pump control accuracy, and low reliability. Improvements are necessary to address these issues. Summary of the Invention

[0003] The purpose of this invention is to provide a defrosting operation method for a heat pump with short defrosting time and low energy loss, so as to overcome the shortcomings of the prior art.

[0004] A defrosting operation method for a heat pump designed for this purpose, comprising a heat pump, characterized in that the operation includes the following steps:

[0005] Step 1: Power on the heat pump, then proceed to Step 2;

[0006] Step two, the heat pump's central controller presets: initial heat pump heating time th, initial defrosting time td, initial coil temperature threshold Tp0 when exiting defrosting, coil temperature threshold Tp1 when exiting the defrosting preheating stage, coil temperature threshold Tp2 when exiting the defrosting stabilization stage, compressor first operating frequency Fa during the defrosting preheating stage, compressor second operating frequency Ft during the defrosting stabilization stage, and compressor third operating frequency Fc during the heating and drying stage. Then proceed to step three, where th... The values ​​range from 20 minutes to 180 minutes, td ranges from 3 minutes to 20 minutes, Tp0 ranges from 10℃ to 60℃, Tp1 ranges from -10℃ to 5℃, Tp2 ranges from 0℃ to 25℃, Tp0 > Tp2 > Tp1, Fa ranges from 60Hz to 100Hz, Ft ranges from 35Hz to 75Hz, and Fc ranges from 10Hz to 50Hz, Fa > Ft > Fc.

[0007] Step 3: The heat pump's central controller controls the heat pump to continuously heat and records the current continuous heating time tx, then proceeds to Step 4;

[0008] Step 4: The central controller determines whether tx≥th is true. If it is true, proceed to step 5; otherwise, proceed to step 3.

[0009] Step 5, proceed to defrosting, then proceed to step 6;

[0010] Step six: The central controller controls the heat pump to defrost. The central controller adjusts the compressor's current operating frequency R to Fa, and then proceeds to step seven.

[0011] Step seven: The compressor starts running; proceed to step eight.

[0012] Step 8: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 9.

[0013] Step 9: The central controller determines whether Tp < Tp1 is true. If it is true, proceed to step 7; otherwise, proceed to step 10.

[0014] Step 10: The central controller determines whether Tp1≤Tp<Tp2 is true. If it is true, proceed to step 11; otherwise, proceed to step 17.

[0015] Step 11: The central controller adjusts the compressor's current operating frequency R to Ft, then proceeds to step 12;

[0016] Step 12: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 13.

[0017] Step 13: The central controller determines whether Tp0≤Tp is true. If it is true, proceed to step 14; otherwise, proceed to step 7.

[0018] Step fourteen: The heat pump completes defrosting, the central controller records the defrosting time Δt, and proceeds to step fifteen;

[0019] Step 15: The central controller determines whether Δt=td is true. If it is true, proceed to step 16; otherwise, proceed to step 20.

[0020] Step sixteen: The central controller maintains the current values ​​of th and Ft, and proceeds to step three;

[0021] Step 17: The central controller adjusts the compressor's current operating frequency R to Fc, then proceeds to step 18;

[0022] Step 18: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 19.

[0023] Step 19: The central controller determines whether Tp0≤Tp is true. If it is true, proceed to step 14; otherwise, proceed to step 7.

[0024] Step 20: The central controller calculates the initial duration of continuous heating of the heat pump in the next heating cycle (th_1) and the second operating frequency (Ft_1) in the next defrost cycle, and then proceeds to step 21.

[0025] Where Ft_1 = Ft*[1 + K*(△t - td) / td],

[0026] th_1=th*[1-Kr*(△t-td) / td],

[0027] K is the first coefficient, and its value ranges from 0.1 to 0.5.

[0028] Kr is the second coefficient, and its value ranges from 0.5 to 0.8.

[0029] Step 21: The central controller assigns the value of th_1 to th and the value of Ft_1 to Ft, then proceeds to step 3.

[0030] This invention divides the defrosting cycle of a heat pump into three stages: 1) Defrosting preheating stage: In this stage, the heat pump needs to heat the temperature of the frost layer on the outdoor coil to above 0°C, which takes a relatively long time and consumes a lot of heat; 2) Defrosting stabilization stage: In this stage, the heat pump needs to consume a lot of heat to defrost until the frost layer on the surface of the outdoor coil is completely melted, which also takes a relatively long time; 3) Defrosting drying stage, which mainly involves vaporizing and drying the water droplets on the surface of the fins of the outdoor coil after defrosting; Then, a dual-variable collaborative control mode is adopted: 1) adopting dynamic Frequency adjustment: Based on the characteristics of the defrosting process, the optimal operating frequency of the compressor is calculated and controlled in real time. High frequency is used for rapid preheating of the frost layer, medium frequency is used for continuous defrosting, and low frequency is used to maintain system pressure safety and dry the evaporator surface; 2) Heat pump continuous heating time correction: Based on the difference between the actual time of the current defrosting cycle and the target defrosting time, the unit's continuous heating time is corrected; thereby reducing defrosting time and energy loss caused by the drop in water temperature due to defrosting; at the same time, it also avoids the phenomenon of incomplete defrosting caused by abnormal faults such as high temperature and high pressure protection during defrosting.

[0031] In summary, the present invention has the advantages of short defrosting time and low energy loss. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the operation process of an embodiment of the present invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] See Figure 1 A defrosting operation method for a heat pump, comprising a heat pump, and the operation includes the following steps:

[0035] Step 1: Power on the heat pump, then proceed to Step 2;

[0036] Step two, the heat pump's central controller presets: initial heat pump heating time th, initial defrosting time td, initial coil temperature threshold Tp0 when exiting defrosting, coil temperature threshold Tp1 when exiting the defrosting preheating stage, coil temperature threshold Tp2 when exiting the defrosting stabilization stage, compressor first operating frequency Fa during the defrosting preheating stage, compressor second operating frequency Ft during the defrosting stabilization stage, and compressor third operating frequency Fc during the heating and drying stage. Then proceed to step three, where th... The values ​​range from 20 minutes to 180 minutes, td ranges from 3 minutes to 20 minutes, Tp0 ranges from 10℃ to 60℃, Tp1 ranges from -10℃ to 5℃, Tp2 ranges from 0℃ to 25℃, Tp0 > Tp2 > Tp1, Fa ranges from 60Hz to 100Hz, Ft ranges from 35Hz to 75Hz, and Fc ranges from 10Hz to 50Hz, Fa > Ft > Fc.

[0037] For the three stages of the defrosting cycle, the defrosting frequency is adaptively controlled: 1) the high-frequency defrosting Fa is used in the defrosting preheating stage; 2) the dynamic adjustment Ft is used in the defrosting stabilization stage; 3) the low-frequency defrosting Fc is used in the heating and drying stage.

[0038] During the defrosting preheating stage, the heat pump outputs less heat and the frost temperature is relatively low at the beginning of defrosting. At this time, the compressor outputs at the preset highest frequency Fa to quickly preheat the frost and shorten the defrosting time.

[0039] During the defrosting stabilization phase, the frost layer on the outdoor coil surface continuously absorbs heat and melts into water. During this process, the compressor operates at the preset optimal medium frequency Ft to ensure sufficient heat for defrosting. At the same time, the stable medium frequency output mechanism prevents high-pressure protection from being triggered, ensuring the defrosting process and system safety.

[0040] During the heating and drying stage, the frost layer on the surface of the outdoor coil has completely melted. In this process, the compressor runs at the preset optimal low frequency Fc to dry the water droplets on the surface of the fins after the outdoor coil has finished defrosting, so as to prevent the water droplets on the surface of the outdoor coil from freezing into ice particles when heating is resumed, thus completely solving the icing phenomenon that occurs when the unit operates for a long time.

[0041] Step 3: The heat pump's central controller controls the heat pump to continuously heat and records the current continuous heating time tx, then proceeds to Step 4;

[0042] Step 4: The central controller determines whether tx≥th is true. If it is true, proceed to step 5; otherwise, proceed to step 3.

[0043] Step 5, proceed to defrosting, then proceed to step 6;

[0044] Step six: The central controller controls the heat pump to defrost. The central controller adjusts the compressor's current operating frequency R to Fa, and then proceeds to step seven.

[0045] Step seven: The compressor starts running; proceed to step eight.

[0046] Step 8: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 9.

[0047] Step 9: The central controller determines whether Tp < Tp1 is true. If it is true, proceed to step 7; otherwise, proceed to step 10.

[0048] Step 10: The central controller determines whether Tp1≤Tp<Tp2 is true. If it is true, proceed to step 11; otherwise, proceed to step 17.

[0049] Step 11: The central controller adjusts the compressor's current operating frequency R to Ft, then proceeds to step 12;

[0050] Step 12: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 13.

[0051] Step 13: The central controller determines whether Tp0≤Tp is true. If it is true, proceed to step 14; otherwise, proceed to step 7.

[0052] Step fourteen: The heat pump completes defrosting, the central controller records the defrosting time Δt, and proceeds to step fifteen;

[0053] Step 15: The central controller determines whether Δt=td is true. If it is true, proceed to step 16; otherwise, proceed to step 20.

[0054] Step sixteen: The central controller maintains the current values ​​of th and Ft, and proceeds to step three;

[0055] Step 17: The central controller adjusts the compressor's current operating frequency R to Fc, then proceeds to step 18;

[0056] Step 18: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 19.

[0057] Step 19: The central controller determines whether Tp0≤Tp is true. If it is true, proceed to step 14; otherwise, proceed to step 7.

[0058] Step 20: The central controller calculates the initial duration of continuous heating of the heat pump in the next heating cycle (th_1) and the second operating frequency (Ft_1) in the next defrost cycle, and then proceeds to step 21.

[0059] Where Ft_1 = Ft*[1 + K*(△t - td) / td],

[0060] th_1=th*[1-Kr*(△t-td) / td],

[0061] K is the first coefficient, and its value ranges from 0.1 to 0.5.

[0062] Kr is the second coefficient, and its value ranges from 0.5 to 0.8.

[0063] Step 21: The central controller assigns the value of th_1 to th and the value of Ft_1 to Ft, then proceeds to step 3.

[0064] Application examples

[0065] The central controller is preset with the following parameters: initial heat pump heating time th = 45 minutes, initial defrosting time td = 7 minutes, initial coil temperature threshold Tp0 = 45℃ when exiting defrosting, coil temperature threshold Tp1 = 1℃ when exiting the defrosting preheating stage, coil temperature threshold Tp2 = 10℃ when exiting the defrosting stabilization stage, compressor first operating frequency Fa = 90Hz during the defrosting preheating stage, compressor second operating frequency Ft = 60Hz during the defrosting stabilization stage, and compressor third operating frequency Fc = 40Hz during the heating and drying stage. The first coefficient K = 0.3, and the second coefficient Kr = 0.6.

[0066] The heat pump starts continuous heating upon power-on and records the current continuous heating time tx, then proceeds to step four. In step four, if the central controller determines that tx ≥ th = 45 minutes, it proceeds to step five; otherwise, it returns to step three to continue continuous heating.

[0067] Of course, the criteria for transitioning from heating mode to defrosting include more than just the comparison between the current continuous heating time (tx) and the initial continuous heating time (th) of the heat pump. However, here, the comparison between the current continuous heating time (tx) and the initial continuous heating time (th) of the heat pump is used as the key trigger condition for entering defrosting mode. Other trigger conditions include an ambient temperature below 10°C and a temperature difference between the ambient temperature and the coil greater than 5°C.

[0068] Step six: The central controller controls the heat pump to defrost. The central controller adjusts the compressor's current operating frequency R to Fa=90Hz, and then proceeds to step seven.

[0069] Step seven: The compressor starts running; proceed to step eight.

[0070] Step 8: After 60 seconds of defrosting, the central controller obtains the current coil temperature Tp = -2℃ on the outdoor coil side, and proceeds to Step 9. The central controller obtains the current coil temperature Tp according to a sampling period of 5 to 20 seconds, the same applies below.

[0071] Step 9: The central controller determines that Tp = -2℃ < Tp1 = 1℃ is true, and proceeds to step 7.

[0072] After 150 seconds of defrosting, the central controller obtains the current coil temperature Tp=1℃ on the outdoor coil and proceeds to step nine.

[0073] The central controller determines that Tp=1℃ < Tp1=1℃ is not true and proceeds to step ten.

[0074] Step 10: When the central controller determines that Tp1=1℃≤Tp=1℃<Tp2=10℃ is true, proceed to step 11.

[0075] Step 11: The central controller adjusts the compressor's current operating frequency R to Ft=60Hz, then proceeds to step 12.

[0076] After 250 seconds of defrosting, the central controller obtains the current coil temperature Tp=8℃ on the outdoor coil and proceeds to step thirteen.

[0077] Step 13: If the central controller determines that Tp0=45℃≤Tp=8℃ is not true, proceed to step 7.

[0078] It should be noted here that in step thirteen, if the central controller determines that Tp0=45℃≤Tp=8℃ is not true, it can proceed to step eleven. This applies when the current external or internal environmental conditions of the heat pump remain unchanged or change only slightly. However, if the current external or internal environmental conditions of the heat pump change significantly, continuing to maintain medium frequency operation with the compressor may not be correct.

[0079] Step 8: After 315 seconds of operation, the central controller obtains the current coil temperature Tp=10℃ on the outdoor coil and proceeds to step 9.

[0080] Step 9: The central controller determines that Tp=10℃<Tp1=1℃ is not true, and proceeds to step 10. The central controller determines that Tp1=1℃≤Tp=10℃<Tp2=10℃ is also not true, and proceeds to step 17.

[0081] Step 17: The central controller adjusts the compressor's current operating frequency R to Fc=40Hz, then proceeds to step 18.

[0082] Step 18: After 365 seconds of defrosting, the central controller obtains the current coil temperature Tp=35℃ on the outdoor coil and proceeds to step 19.

[0083] Step 19: The central controller determines that Tp0=45℃≤Tp=35℃ is not true, and proceeds to step 7.

[0084] After 400 seconds of defrosting operation, the central controller obtains the current coil temperature Tp = 45℃ on the outdoor coil, which remains constant for 5 seconds.

[0085] In step nineteen, the central controller determines that Tp0=45℃≤Tp=45℃ is true, and proceeds to step fourteen.

[0086] Step fourteen: The heat pump completes defrosting, and the central controller records the defrosting time Δt = 400 seconds, then proceeds to step fifteen.

[0087] Step 15: The central controller determines that Δt = 400 seconds = td = 7 minutes is not true, and proceeds to step 20.

[0088] Step 20

[0089] Ft_1=Ft*[1+K*(△t-td) / td]=60*[1+0.3*(400-420) / 420]=59Hz;

[0090] th_1=th*[1-Kr*(△t-td) / td]=45*[1-0.6*(400-420) / 420]=46.3 minutes.

[0091] Proceeding to step twenty-one, the central controller assigns the value of th_1 to th and the value of Ft_1 to Ft. Therefore, in the next heating cycle, th = 46.3 minutes and Ft = 59Hz; proceeding to step three. Until the user shuts down the device.

[0092] When the user powers on the device again, th and Ft return to their initial values, i.e., th = 45 minutes and Ft = 60Hz.

[0093] If in step thirteen, the central controller determines that Tp0≤Tp is true, then proceed directly to step fourteen.

[0094] In the description of this invention, it should be understood that the orientation or positional relationship indicated by the terms is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the invention. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0095] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A defrosting operation method for a heat pump, comprising a heat pump, characterized in that: The operation includes the following steps: Step 1: Power on the heat pump, then proceed to Step 2; Step two, the heat pump's central controller presets: initial heat pump heating time th, initial defrosting time td, initial coil temperature threshold Tp0 when exiting defrosting, coil temperature threshold Tp1 when exiting the defrosting preheating stage, coil temperature threshold Tp2 when exiting the defrosting stabilization stage, compressor first operating frequency Fa during the defrosting preheating stage, compressor second operating frequency Ft during the defrosting stabilization stage, and compressor third operating frequency Fc during the heating and drying stage. Then proceed to step three, where th... The values ​​range from 20 minutes to 180 minutes, td ranges from 3 minutes to 20 minutes, Tp0 ranges from 10℃ to 60℃, Tp1 ranges from -10℃ to 5℃, Tp2 ranges from 0℃ to 25℃, Tp0 > Tp2 > Tp1, Fa ranges from 60Hz to 100Hz, Ft ranges from 35Hz to 75Hz, and Fc ranges from 10Hz to 50Hz, Fa > Ft > Fc. Step 3: The heat pump's central controller controls the heat pump to continuously heat and records the current continuous heating time tx, then proceeds to Step 4; Step 4: The central controller determines whether tx≥th is true. If it is true, proceed to step 5; otherwise, proceed to step 3. Step 5, proceed to defrosting, then proceed to step 6; Step six: The central controller controls the heat pump to defrost. The central controller adjusts the compressor's current operating frequency R to Fa, and then proceeds to step seven. Step seven: The compressor starts running; proceed to step eight. Step 8: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 9. Step 9: The central controller determines whether Tp < Tp1 is true. If it is true, proceed to step 7; otherwise, proceed to step 10. Step 10: The central controller determines whether Tp1≤Tp<Tp2 is true. If it is true, proceed to step 11; otherwise, proceed to step 17. Step 11: The central controller adjusts the compressor's current operating frequency R to Ft, then proceeds to step 12; Step 12: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 13. Step 13: The central controller determines whether Tp0≤Tp is true. If it is true, proceed to step 14; otherwise, proceed to step 7. Step fourteen: The heat pump completes defrosting, the central controller records the defrosting time Δt, and proceeds to step fifteen; Step 15: The central controller determines whether Δt=td is true. If it is true, proceed to step 16; otherwise, proceed to step 20. Step sixteen: The central controller maintains the current values ​​of th and Ft, and proceeds to step three; Step 17: The central controller adjusts the compressor's current operating frequency R to Fc, then proceeds to step 18; Step 18: After a period of operation, the central controller obtains the current coil temperature Tp of the outdoor coil and proceeds to step 19. Step 19: The central controller determines whether Tp0≤Tp is true. If it is true, proceed to step 14; otherwise, proceed to step 7. Step 20: The central controller calculates the initial duration of continuous heating of the heat pump in the next heating cycle (th_1) and the second operating frequency (Ft_1) in the next defrost cycle, and then proceeds to step 21. Among them, Ft_1=Ft*[1+K*(△t-td) / td], th_1=th*[1-Kr*(△t-td) / td], K is the first coefficient, and its value ranges from 0.1 to 0.

5. Kr is the second coefficient, and its value ranges from 0.5 to 0.

8. Step 21: The central controller assigns the value of th_1 to th and the value of Ft_1 to Ft, then proceeds to step 3.

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