CN110906581A - Defrosting method of variable-frequency air source heat pump unit - Google Patents
Defrosting method of variable-frequency air source heat pump unit Download PDFInfo
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- CN110906581A CN110906581A CN201911220531.0A CN201911220531A CN110906581A CN 110906581 A CN110906581 A CN 110906581A CN 201911220531 A CN201911220531 A CN 201911220531A CN 110906581 A CN110906581 A CN 110906581A
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- frequency
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B13/00—Compression machines, plants or systems, with reversible cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
- F04C29/06—Silencing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
- F25B47/02—Defrosting cycles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/022—Compressor control arrangements
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The invention provides a defrosting method of a variable-frequency air source heat pump unit, which comprises the following steps: and when the defrosting condition is reached, the compressor reduces the frequency to the lowest frequency and keeps the frequency for 5 seconds, the defrosting mode is entered, the frequency of the compressor is increased to the defrosting frequency, the expansion opening degree is adjusted to the defrosting opening degree, then, the defrosting frequency is reduced by 5Hz and the defrosting opening degree is reduced by 4 percent every 30 seconds until the frequency is reduced to the defrosting lower limit frequency, and the adjustment is stopped. And monitoring the wind exchange temperature, the high pressure value of the unit and the defrosting time, when any parameter of the three exceeds a set value, the unit quits defrosting, the compressor reduces the frequency to the lowest frequency and keeps for 5 seconds, the fan is started and waits for 5 seconds, and the unit is switched back to normal heating. The method can reduce the impact of defrosting switching of the air source heat pump, improve the safety of the unit and reduce the noise. Meanwhile, the real-time matching of defrosting heat demand and unit heat supply can be kept, the total defrosting time is shortened, and the defrosting energy consumption is reduced.
Description
Technical Field
The invention relates to the technical field of air source heat pumps, in particular to a defrosting method of a variable-frequency air source heat pump.
Background
Defrosting is always a difficult problem of preventing further development and popularization of an air source heat pump, and on the premise of keeping the unit to operate reliably, the core of the defrosting technology is to accelerate defrosting speed and reduce defrosting energy consumption. At present, a main air source heat pump unit adopts a fixed-frequency scroll compressor and an R410A refrigerant, and a defrosting control method generally comprises the following steps: and after the defrosting condition is met and the unit is stopped for a period of time, the four-way valve is switched, and the compressor is started again to defrost. And detecting the temperature of the heat exchanger during defrosting, and stopping defrosting of the unit when the temperature exceeds a certain value. At the moment, the compressor stops for a period of time again, then the four-way valve is switched, and the normal heating mode is entered.
The defrosting method is safe, reliable, simple and easy to control, but has the following defects:
1) the pressure of the R410A refrigerant is high, in order to avoid impact and oil return safety of defrosting high-pressure and low-pressure switching on a system, the system needs to be stopped for a period of time before and after defrosting, so that the high-pressure and low-pressure difference is reduced, and the time for actual defrosting is prolonged.
2) The heating quantity required for defrosting is reduced as the frost is gradually melted, and the defrosting quantity of the fixed-frequency compressor is gradually increased in the defrosting process. This kind of mismatch has caused the defrosting not enough in earlier stage heating capacity, has prolonged the time of defrosting, also makes the later stage too big to the defrosting heat of fin heat exchanger output, and during partial heat directly gived off outdoor cold air, the defrosting loss increase, high-pressure protection appears easily in the system simultaneously, is unfavorable for system reliability.
3) Considering the safety of the compressor operation, the time from the closing to the next opening of the compressor is generally not less than 3 minutes. However, the defrost time cannot be too long, so the typical pre-defrost and post-defrost downtime is set to tens of seconds, much shorter than the recommended 3 minutes. The primary defrosting compressor needs to be started and stopped for 2 times, when frosting is serious, 1-2 times of defrosting can be carried out within 1 hour, and influence on safe operation of the compressor is avoided. On the other hand, the fixed-frequency scroll compressor is generally directly started, has higher noise and also influences the satisfaction degree of users.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a defrosting method of a variable-frequency air source heat pump unit, which can reduce the impact of defrosting switching of the air source heat pump, improve the safety of the unit, reduce noise, reduce defrosting time and reduce defrosting energy consumption. The technical scheme adopted by the invention is as follows:
the embodiment of the invention provides a defrosting method of a variable-frequency air source heat pump unit, which comprises the following steps:
a) after the unit reaches the defrosting condition, the frequency of the variable frequency compressor is reduced until the high-low pressure difference of the unit is less than a set valueP sOr the compressor frequency reaches the lowest operating frequencyf minStopping reducing the frequency and keeping the first set keeping time length (the default value is 5 seconds);
b) the unit enters a defrosting mode, the four-way valve is switched, the fan of the air heat exchanger is closed, and the electronic expansion valve is adjusted to the defrosting opening degreeL sCompressor raising frequency to defrost setting frequencyf s；
c) Compressor frequency up tof sThen, every set frequency adjustment interval (default value of 30 seconds), the frequency of the compressor is reduced by a set frequency reduction range (default value of 5 Hz), the opening of the electronic expansion valve is reduced by a set opening reduction proportion (default value of 4%); when detecting that the compressor frequency is lower thanf a The frequency and the opening degree of the electronic expansion valve are not adjusted;f min<f a <f s；
d) the defrost is exited when any of three conditions are triggered, ① air exchange temperaturet exThe high pressure value of the ② unit is higher than the set wind exchange temperature (the default value is 5 ℃), and the high pressure value of the ② unit is higher than the set maximum valueP max ③ defrost duration exceeds the set defrost duration (default 5 minutes) when the compressor frequency drops to the minimum frequencyf minKeeping the second set holding time (default value 5 seconds), and then starting a fan of the air heat exchanger;
e) and after the fan of the air heat exchanger is started and the third set holding time (the default value is 5 seconds) is kept, the unit recovers the heating mode, the four-way valve is switched, and the compressor and the electronic expansion valve are controlled and adjusted according to the unit.
The aboveP s、f min、L s、f s、P max 、f a All adjustable according to different units.
The first set holding time is 5 seconds, the second set holding time is 5 seconds, the third set holding time is 5 seconds, the set frequency adjustment interval is 30 seconds, the set frequency reduction amplitude of the compressor is 5Hz, the set opening degree reduction proportion of the electronic expansion valve is 4 percent, the set air exchange temperature is 5 ℃, the set defrosting time is 5 minutes, and the like are default values and can be adjusted according to the actual situation.
The defrosting method effectively solves the existing unit defrosting problems listed above, reduces the high-low pressure difference and the refrigerant flow through the compressor during defrosting switching, enables the switching of the defrosting working condition and the heating working condition to be more stable and safer, avoids the hidden trouble of compressor operation caused by shutdown switching, avoids the starting noise of the compressor, and shortens the switching time. On the other hand, after the defrosting operation condition is started, the frequency of the compressor is quickly increased to output heat as soon as possible, the high heat requirement of the initial defrosting stage is met, and the defrosting speed is accelerated. And the frost layer is gradually melted in the later period, the frequency of the unit is reduced, the output heat is reduced, and the ineffective heat loss is avoided. Further reducing the defrosting time and the defrosting energy consumption.
The defrosting method effectively solves the existing unit defrosting problems listed above, reduces the high-low pressure difference and the refrigerant flow through the compressor during defrosting switching, enables the switching of the defrosting working condition and the heating working condition to be more stable and safer, avoids the hidden trouble of compressor operation caused by shutdown switching, avoids the starting noise of the compressor, and shortens the switching time. On the other hand, after the defrosting operation condition is started, the frequency of the compressor is quickly increased to output heat as soon as possible, the high heat requirement of the initial defrosting stage is met, and the defrosting speed is accelerated. And the frost layer is gradually melted in the later period, the frequency of the unit is reduced, the output heat is reduced, and the ineffective heat loss is avoided. Further reducing the defrosting time and the defrosting energy consumption.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
The invention is further illustrated by the following specific figures and examples.
The air source heat pump frosts to a certain degree, and the unit generates a defrosting signal. At this time, in order to reduce the high-low pressure difference and the flow rate of the unit so as to reduce the impact of the subsequent defrosting mode switching, the frequency of the variable frequency compressor starts to decrease. Until the high-low pressure difference of the unit is less than the set valueP sOr the compressor frequency reaches the lowest operating frequencyf minThe down-conversion is stopped and held for 5 seconds. In special cases, if the compressor frequency at the moment of the unit is not more thanf minOr the pressure difference between high and low pressures is not higher thanP sThe unit maintains this frequency constant and remains for 5 seconds. Differential pressure set pointP sAnd minimum operating frequency of compressorf minAnd the default value is determined according to the unit characteristics, and the device has certain adjusting capability when leaving a factory. During the time that the unit is reducing the frequency and remaining stable, the unit is continuously in heating, only because the frequency is reduced, the heating capacity is reduced.
Then the unit enters a defrosting mode, the four-way valve is switched, the fan of the air heat exchanger is closed, and the electronic expansion valve is adjusted to the defrosting opening degreeL sThe compressor rapidly increases the frequency to the defrosting setting frequencyf sAnd maintained. The unit is in the maximum output state, so that the temperature of the air heat exchanger is rapidly increased, and the defrosting speed is accelerated. Defrost setting frequencyf sThe larger the output of the unit, the faster the defrosting, but the larger the noise and vibration. Considering that the heat required for defrosting is gradually reduced as the frost is melted, a variable frequency defrosting method is adopted: increasing the frequency of the compressor tof sThen, the compressor frequency is decreased by 5Hz every 30 seconds, and the corresponding opening of the electronic expansion valve is also decreased by 4% (for the conventional 500-step expansion valve, i.e. 20 steps). Generally, the actual defrosting time is about tens of seconds to several minutes, and the method can be properly improvedf sValue, toThe defrosting heat output at the high initial stage does not have to worry about the problem of noise and vibration because the highest frequency lasts only 30 seconds. In order to ensure that the defrosting frequency is not too low, a condition is also set: when detecting that the compressor frequency is lower thanf a Both the frequency and the expansion valve opening are no longer reduced.
During the period of frost melting, the temperature is changed by windt exAll are kept at about 0 deg.C until most of frost is meltedt exWill gradually increase so that this value is the primary condition for judging defrost exit. Meanwhile, the defrosting time cannot be too long, and the high pressure of the unit cannot be too high, so that the unit exits defrosting conditions as follows:
1) wind temperaturet exAbove 5 ℃;
2) high pressure value of the unit is higher thanP max ；
3) The defrosting time is longer than 5 minutes;
the defrosting is exited when any one of the three conditions is triggered, and the frequency of the compressor is reduced to the minimum frequencyf minAnd held for 5 seconds. During the down-conversion process and the 5 second waiting time thereafter, the unit is in fact still in the low frequency defrost mode, which ensures the defrost thoroughness without causing excessive power consumption. And then, a fan of the air heat exchanger is started to ensure the evaporation of the residual defrosting water on the fins. In order to prevent the excessive heat dissipation of the air heat exchanger, the fan of the air heat exchanger is opened for only 5 seconds, then the unit recovers normal heating, the four-way valve is switched back to the heating mode, and the compressor and the expansion valve are correspondingly adjusted according to the control of the unit.
The control method is suitable for different air source heat pump units, and various parameters mentioned in the method, such as design difference and application difference of different units, are consideredP s、f min、L s、f s、P max 、f a A first set holding period of 5 seconds, a second set holding period of 5 seconds, a third set holding period of 5 seconds, a set frequency adjustment interval of 30 seconds, a set frequency reduction range of 5Hz of the compressor, and electricityThe set opening degree of the sub-expansion valve is reduced by 4 percent, the set air exchange temperature is 5 ℃, and the set defrosting time is 5 minutes, which can be adjusted in a certain range, so as to ensure that different units can exert the optimal defrosting effect.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (8)
1. A defrosting method of a variable-frequency air source heat pump unit is characterized by comprising the following steps:
a) after the unit reaches the defrosting condition, the frequency of the variable frequency compressor is reduced until the high-low pressure difference of the unit is less than a set valueP sOr the compressor frequency reaches the lowest operating frequencyf minStopping reducing the frequency and keeping the first set holding time;
b) the unit enters a defrosting mode, the four-way valve is switched, the fan of the air heat exchanger is closed, and the electronic expansion valve is adjusted to the defrosting opening degreeL sCompressor raising frequency to defrost setting frequencyf s；
c) Compressor frequency up tof sThen, the frequency of the compressor is reduced at intervals of set frequency adjustment, the frequency reduction range is set, and the opening of the electronic expansion valve is reduced by a set opening reduction proportion; when detecting that the compressor frequency is lower thanf a The frequency and the opening degree of the electronic expansion valve are not adjusted;f min<f a <f s；
d) the defrost is exited when any of three conditions are triggered, ① air exchange temperaturet exWhen the set wind exchange temperature is higher than the set wind exchange temperature, the high pressure value of the ② unit is higher than the set maximum valueP max ③ defrost duration exceeds the set defrost duration when the compressor frequency drops to the minimum frequencyf minKeeping the second set holding time, and then starting a fan of the air heat exchanger;
e) and after the fan of the air heat exchanger is started and is kept for a third set holding time, the unit recovers the heating mode, the four-way valve is switched, and the compressor and the electronic expansion valve are controlled and adjusted according to the unit.
2. The defrosting method of the variable-frequency air source heat pump unit according to claim 1,
the above-mentionedP s、f min、L s、f s、P max 、f a All adjustable according to different units.
3. The defrosting method of the variable-frequency air source heat pump unit according to claim 1,
a first set holding period default of 5 seconds, a second set holding period default of 5 seconds, and a third set holding period default of 5 seconds.
4. The defrosting method of the variable-frequency air source heat pump unit according to claim 1,
the frequency adjustment interval default is set to 30 seconds.
5. The defrosting method of the variable-frequency air source heat pump unit according to claim 1,
the set frequency of the compressor is reduced by a default value of 5 Hz.
6. The defrosting method of the variable-frequency air source heat pump unit according to claim 1,
the set opening degree of the electronic expansion valve is reduced by a default value of 4%.
7. The defrosting method of the variable-frequency air source heat pump unit according to claim 1,
the default value of the air exchange temperature is set to be 5 ℃.
8. The defrosting method of the variable-frequency air source heat pump unit according to claim 1,
a default value of 5 minutes is set for the defrosting time period.
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| CN201911220531.0A CN110906581A (en) | 2019-12-03 | 2019-12-03 | Defrosting method of variable-frequency air source heat pump unit |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111895654A (en) * | 2020-06-24 | 2020-11-06 | 青岛海尔新能源电器有限公司 | Control method and control device of heat pump water heater |
| CN112432404A (en) * | 2020-11-04 | 2021-03-02 | 珠海格力电器股份有限公司 | Defrosting control method and device for heat pump air conditioning unit, controller and air conditioning system |
| CN113959062A (en) * | 2021-10-29 | 2022-01-21 | 青岛海尔空调电子有限公司 | Air conditioner defrosting control method and device and air conditioner |
| CN114234468A (en) * | 2021-12-15 | 2022-03-25 | 广东芬尼克兹节能设备有限公司 | Heat pump device control method, device, unit, computer equipment and storage medium |
| CN114719395A (en) * | 2022-03-17 | 2022-07-08 | 浙江中广电器集团股份有限公司 | Control method for solving abnormal noise of internal machine after defrosting |
| CN115059994A (en) * | 2022-03-16 | 2022-09-16 | 北京小米移动软件有限公司 | Air conditioner control method and device and storage medium |
| CN115247910A (en) * | 2022-06-28 | 2022-10-28 | 浙江中广电器集团股份有限公司 | Method for controlling overhigh pressure in defrosting process |
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| CN1987235A (en) * | 2005-12-22 | 2007-06-27 | 乐金电子(天津)电器有限公司 | Defrost operation control method for heating and cooling two-purpose air conditioner |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111895654A (en) * | 2020-06-24 | 2020-11-06 | 青岛海尔新能源电器有限公司 | Control method and control device of heat pump water heater |
| CN112432404A (en) * | 2020-11-04 | 2021-03-02 | 珠海格力电器股份有限公司 | Defrosting control method and device for heat pump air conditioning unit, controller and air conditioning system |
| CN113959062A (en) * | 2021-10-29 | 2022-01-21 | 青岛海尔空调电子有限公司 | Air conditioner defrosting control method and device and air conditioner |
| CN113959062B (en) * | 2021-10-29 | 2023-02-28 | 青岛海尔空调电子有限公司 | Air conditioner defrosting control method and device and air conditioner |
| WO2023071148A1 (en) * | 2021-10-29 | 2023-05-04 | 青岛海尔空调电子有限公司 | Defrosting control method and apparatus for air conditioner, and air conditioner |
| CN114234468A (en) * | 2021-12-15 | 2022-03-25 | 广东芬尼克兹节能设备有限公司 | Heat pump device control method, device, unit, computer equipment and storage medium |
| CN114234468B (en) * | 2021-12-15 | 2023-08-18 | 广东芬尼克兹节能设备有限公司 | Heat pump device control method, device, unit, computer equipment and storage medium |
| CN115059994A (en) * | 2022-03-16 | 2022-09-16 | 北京小米移动软件有限公司 | Air conditioner control method and device and storage medium |
| CN114719395A (en) * | 2022-03-17 | 2022-07-08 | 浙江中广电器集团股份有限公司 | Control method for solving abnormal noise of internal machine after defrosting |
| CN115247910A (en) * | 2022-06-28 | 2022-10-28 | 浙江中广电器集团股份有限公司 | Method for controlling overhigh pressure in defrosting process |
| CN115247910B (en) * | 2022-06-28 | 2024-04-02 | 浙江中广电器集团股份有限公司 | Method for controlling excessive pressure in defrosting process |
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