CN112611139B - Defrosting and pressure adjusting method of heat pump dryer - Google Patents
Defrosting and pressure adjusting method of heat pump dryer Download PDFInfo
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- CN112611139B CN112611139B CN202011517199.7A CN202011517199A CN112611139B CN 112611139 B CN112611139 B CN 112611139B CN 202011517199 A CN202011517199 A CN 202011517199A CN 112611139 B CN112611139 B CN 112611139B
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- 238000010257 thawing Methods 0.000 title claims abstract description 77
- 238000000034 method Methods 0.000 title claims abstract description 42
- 239000007788 liquid Substances 0.000 claims abstract description 42
- 238000004781 supercooling Methods 0.000 claims description 29
- 239000003507 refrigerant Substances 0.000 claims description 17
- 238000002347 injection Methods 0.000 claims description 15
- 239000007924 injection Substances 0.000 claims description 15
- 238000009833 condensation Methods 0.000 claims description 9
- 230000005494 condensation Effects 0.000 claims description 9
- 230000001105 regulatory effect Effects 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 7
- 230000017525 heat dissipation Effects 0.000 claims description 5
- 238000001035 drying Methods 0.000 abstract description 12
- 230000008719 thickening Effects 0.000 abstract description 5
- 230000007306 turnover Effects 0.000 abstract 2
- 238000004134 energy conservation Methods 0.000 abstract 1
- 230000009467 reduction Effects 0.000 description 3
- 206010063385 Intellectualisation Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
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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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/06—Controlling, e.g. regulating, parameters of gas supply
- F26B21/10—Temperature; Pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B23/00—Heating arrangements
- F26B23/001—Heating arrangements using waste heat
- F26B23/002—Heating arrangements using waste heat recovered from dryer exhaust gases
- F26B23/005—Heating arrangements using waste heat recovered from dryer exhaust gases using a closed cycle heat pump system ; using a heat pipe system
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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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2513—Expansion valves
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
- Y02P60/80—Food processing, e.g. use of renewable energies or variable speed drives in handling, conveying or stacking
- Y02P60/85—Food storage or conservation, e.g. cooling or drying
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- Thermal Sciences (AREA)
- Defrosting Systems (AREA)
Abstract
The invention discloses a method for defrosting and adjusting pressure of a heat pump dryer, when the ambient temperature Tw is less than or equal to a defrosting allowable temperature Ts, a unit is marked after running for 10 minutes, the temperature difference of inlet air and outlet air is marked as a calibration temperature difference and is used as a reference value of a frostless state, and the current of a fan at the moment is marked as a calibration current Ls; because the fan current is normal under the condition of not having the frost, but along with the thickening of frosting, the amount of wind slowly reduces, and the difference in temperature of business turn over wind reduces thereupon, and the frosting leads to the windage to increase and leads to fan motor power consumption to increase, and the frost that the evaporimeter was frosted along with current increase ceaselessly thickens, can accurately judge the condition of frosting through contrast business turn over wind difference in temperature, fan current and return air and ambient temperature difference. The invention uses high-temperature liquid for defrosting, carries out defrosting under the condition of not reducing the temperature of the drying room, ensures the defrosting safety and the service life of the machine, has high efficiency and energy conservation, and ensures the stable and accurate defrosting of the machine by applying an intelligent defrosting judgment method.
Description
Technical Field
The invention relates to the technical field of air conditioners and heat pumps, in particular to a defrosting and pressure adjusting method of a heat pump dryer.
Background
The traditional defrosting method of the heat pump comprises the following steps: reverse cycle defrosting, electric heating defrosting, hot gas bypass defrosting, wherein the four-way valve is switched to carry out Carnot cycle during reverse cycle defrosting, the room temperature is reduced, and the quality of a product is influenced due to temperature reduction during drying special articles, so that loss of customers is caused, and the reverse cycle defrosting is not preferable. In addition, the outdoor unit is easy to cause electric leakage and fire due to long-time blowing and raining, and the heating belt is easy to damage. The hot gas bypass defrosting directly guides the high-temperature and high-pressure gaseous refrigerant at the exhaust port into the evaporator, and then returns to the compressor through the fins, so that the compressor is easily damaged for a long time.
In addition, for the heat pump dryer, because the temperature fluctuation is large, the judgment is difficult to be carried out only by the difference between the environment and the temperature of the coil. Because the drying room temperature difference that the drying-machine used changes greatly, lead to the pressure too high very easily at the in-process that heaies up rapidly, trigger high-voltage switch very easily, lead to the machine trouble can't work, because the machine stop work just can't maintain the temperature in drying-room, influence product quality when serious. If the problem is solved by increasing the air volume, because some products have the requirement of air speed in the drying process, the air volume cannot be increased by simply increasing the air volume, and the operation cost is increased undoubtedly by increasing the fan. It can also be solved by enlarging the area of the condenser, but this will increase the cost considerably.
The present invention has been made to solve these problems.
Disclosure of Invention
The invention aims to provide a method for defrosting and regulating pressure of a heat pump dryer, which solves the problems of frosting detection, defrosting and overhigh drying pressure of an open-loop dryer.
The purpose of the invention is realized by the following technical scheme:
a method of defrosting and regulating pressure of a heat pump dryer, the defrosting method comprising the steps of:
1) after a heat pump unit is started, firstly detecting the ambient temperature Tw, and when the ambient temperature Tw is less than or equal to the defrosting allowable temperature Ts, marking the temperature difference of inlet air and outlet air and the current of a fan as a calibration temperature difference and a calibration current when the heat pump unit runs for 10 minutes;
2) measuring the air inlet and outlet temperature difference again, detecting and calculating the difference T1 between the air inlet and outlet temperature difference and the calibration temperature difference, the difference T2 between the fan current and the calibration current, and detecting the difference T3 between the return air temperature and the environment temperature;
3) if the temperature is more than 5 percent and less than or equal to T1 and less than or equal to 8 percent, and simultaneously, the temperature is more than 5 percent and less than T2 and less than 8 percent, and simultaneously, the defrosting treatment is carried out after 60 minutes when the temperature is more than 3 ℃ and less than T3 and less than 8 ℃;
if the temperature is more than 8 percent and less than T1 and less than 11 percent, and simultaneously, the temperature is more than 8 percent and less than T2 and less than 11 percent, and simultaneously, the defrosting treatment is carried out after 45 minutes when the temperature is more than 8 ℃ and less than T3 and less than 13 ℃;
if the temperature is more than 11% < T1 and less than or equal to 14%, and the temperature is more than 11% < T2 and less than 14%, and the temperature is more than 13 ℃ and less than T3 and less than 18 ℃, defrosting treatment is carried out after 30 minutes;
if the temperature is more than 14% < T1 and less than or equal to 17%, and simultaneously the temperature is more than 14% < T2 and less than 17%, and simultaneously the temperature is more than 18 ℃ and less than T3 and less than 23 ℃, defrosting treatment is carried out within 20 minutes;
if 17% < T1 ≦ 20%, and 17% < T2 < 20%, and 23 deg.C < T3 < 28 deg.C, the defrosting treatment is carried out for 10 minutes.
Further, the heat pump dryer comprises a heat pump unit; the system comprises a compressor, a gas-liquid separator and a four-way valve, wherein a loop is formed by the compressor, the gas-liquid separator and the four-way valve through pipelines, the other end of the compressor is connected with an enhanced vapor injection economizer, an auxiliary outlet temperature sensor is connected to a pipeline between the compressor and the enhanced vapor injection economizer, one end of the enhanced vapor injection economizer is connected with a first liquid storage device through a pipeline, a main inlet temperature sensor is arranged on the pipeline, one end of the enhanced vapor injection economizer is connected with an enhanced vapor electronic expansion valve through a pipeline, and an auxiliary inlet temperature sensor is arranged on the pipeline; one end of the enhanced vapor injection economizer is connected with a main circuit electronic expansion valve through a pipeline, and a main circuit outlet temperature sensor is arranged on the pipeline; the other end of the enthalpy-increasing electronic expansion valve is connected to a pipeline between the main outlet temperature sensor and the main electronic expansion valve; the other end of the main electronic expansion valve is connected with the evaporator through a pipeline, and the evaporator is provided with a coil pipe temperature sensor, an evaporator air inlet temperature sensor and an evaporator air outlet temperature sensor; the other end of the evaporator is connected with a four-way valve through a pipeline; one end of the four-way valve is connected with the condenser through a pipeline, the other end of the condenser is connected with a first liquid storage device, the other end of the first liquid storage device is connected with a section of pipeline, two parallel branches are led out from the section of pipeline, a solenoid valve is arranged on one branch, an electronic expansion valve, a second liquid storage device and a one-way valve are sequentially arranged on the other branch, and the other ends of the solenoid valve and the one-way valve are connected to a pipeline between the evaporator and the main-path electronic expansion valve; the evaporator air inlet temperature sensor and the evaporator air outlet temperature sensor can be used for measuring the air inlet temperature and the air outlet temperature of the evaporator, and the difference value is the temperature difference of inlet air and outlet air; the return air temperature sensor can be used to measure the return air temperature.
The defrosting process comprises the following steps: the evaporator fan stops running, the condenser fan keeps running, the electromagnetic valve is opened, and high-temperature liquid refrigerant flows to the evaporator from the first liquid storage device.
The defrost process further comprises the steps of: and if the temperature difference of the auxiliary road is too small and the temperature difference of the main road is too large, the enthalpy-increasing electronic expansion valve and the main road electronic expansion valve are closed.
The exit steps of the defrost process are as follows: when the temperature of the coil pipe is higher than the defrosting exit temperature, the machine exits the defrosting treatment, the electromagnetic valve is closed, and the enthalpy-increasing electronic expansion valve and the main-path electronic expansion valve are correspondingly adjusted.
The method for adjusting the pressure of the heat pump dryer comprises the steps of detecting the pressure value of a high-pressure sensor, opening an electronic expansion valve when the pressure value reaches a set value, and guiding liquid refrigerants of a condenser into a first liquid storage device and a second liquid storage device to increase the heat dissipation area of the condenser.
Further, the control method of the electronic expansion valve comprises the following steps:
1) measuring a pressure value P detected by the high-pressure sensor;
2) when 40bar is more than P and more than 38bar, if the temperature is more than 3 ℃ and the supercooling degree is more than 1 ℃, the electronic expansion valve is opened by 30 percent;
when 41bar is more than P and more than 39bar, if 4 ℃ is more than supercooling degree and more than 2 ℃, the electronic expansion valve is opened by 50 percent;
when 42bar is more than P and more than 40bar, if the temperature is more than 5 ℃ and the supercooling degree is more than 3 ℃, the electronic expansion valve is opened by 70 percent;
when 43bar is more than P and more than 41bar, and when 7 ℃ is more than supercooling degree and more than 4 ℃, the electronic expansion valve opens 100 percent.
The degree of supercooling is a condensation temperature-fin outlet temperature, the condensation temperature being a condensation temperature of a liquid refrigerant of the condenser, and the fin outlet temperature being a fin outlet temperature of the condenser.
The invention has the beneficial effects that:
1. the invention uses high-temperature liquid for defrosting, carries out defrosting under the condition of not reducing the temperature of the drying room, ensures the defrosting safety and the service life of the machine, and has high efficiency and energy saving.
2. The method is suitable for an open-loop type drying system, changes of air inlet and outlet temperature differences of fins and fan current are used, frosting conditions are judged by combining air suction and environment temperature differences, defrosting is carried out by using a high-temperature liquid refrigerant, when the pressure of the machine is higher, pressure reduction is carried out, the condition that the drying quality is influenced by the stop of the machine is avoided, and data causing high pressure are recorded and reasons are analyzed.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a schematic view of the heat pump unit of the present invention.
Fig. 2 is a flow chart of the defrosting method of the heat pump dryer of the invention.
Fig. 3 is a flow chart of a method for regulating pressure in a heat pump dryer according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention relates to a defrosting and pressure adjusting method of a heat pump dryer, which uses the temperature difference of inlet air and outlet air of an evaporator and the change of the current of a fan of the evaporator, and the frosting condition is comprehensively judged by combining the return air temperature and the environmental temperature difference, the method can accurately judge the frosting condition and accurately send a defrosting instruction, when frosting begins, the temperature difference of inlet and outlet air is the largest, the temperature difference is smaller and smaller along with the continuous thickening of the frost layer, because of the thickening of the frost layer, the resistance of the fan of the evaporator is increased, so that the power and the current of the fan are increased, the current of the fan can be detected, at the same time, the final judgment is carried out on the difference between the suction air and the ambient temperature, because the frost layer is thickened, the refrigerant of the evaporator can not be evaporated, thereby causing the liquid return of the compressor, therefore, the liquid return condition of the compressor can be judged through the difference between the return air and the ambient temperature, and the functions of judging and protecting the compressor are achieved.
The heat pump dryer comprises a heat pump unit.
Referring to fig. 1, the heat pump unit is composed of a compressor 1, an exhaust temperature sensor 2, a high-pressure sensor 3, a condenser 4, a first liquid storage 5, a main intake temperature sensor 6, a main outlet temperature sensor 7, an auxiliary intake temperature sensor 8, an auxiliary outlet temperature sensor 9, an enthalpy-increasing electronic expansion valve 10, a main electronic expansion valve 11, a solenoid valve 12, an electronic expansion valve 13, a one-way valve 14, a coil pipe temperature sensor 15, an evaporator 16, a gas-liquid separator 17, a low-pressure sensor 18, a return air temperature sensor 19, a second liquid storage 20, an evaporator air inlet temperature sensor 21 and an evaporator air outlet temperature sensor 22; the system comprises a compressor 1, a gas-liquid separator 17 and a four-way valve, wherein a loop is formed by the compressor 1, the gas-liquid separator 17 and the four-way valve through pipelines, the other end of the compressor 1 is connected with an enhanced vapor injection economizer, an auxiliary outlet temperature sensor 9 is connected to the pipeline between the compressor 1 and the enhanced vapor injection economizer, one end of the enhanced vapor injection economizer is connected with a first liquid storage device 5 through the pipeline, a main inlet temperature sensor 6 is arranged on the pipeline, one end of the enhanced vapor injection economizer is connected with an enhanced vapor electronic expansion valve 10 through the pipeline, and an auxiliary inlet temperature sensor 8 is arranged on the pipeline; one end of the enhanced vapor injection economizer is connected with a main circuit electronic expansion valve 11 through a pipeline, and a main circuit outlet temperature sensor 7 is arranged on the pipeline; the other end of the enthalpy-increasing electronic expansion valve 10 is connected to a pipeline between the main outlet temperature sensor 7 and the main electronic expansion valve 11; the other end of the main electronic expansion valve 11 is connected with an evaporator 16 through a pipeline, and a coil temperature sensor 15, an evaporator air inlet temperature sensor 21 and an evaporator air outlet temperature sensor 22 are arranged on the evaporator 16; the other end of the evaporator 16 is connected with a four-way valve through a pipeline; one end of the four-way valve is connected with a condenser 4 through a pipeline, the other end of the condenser 4 is connected with a first liquid storage device 5, the other end of the first liquid storage device 5 is connected with a section of pipeline, two parallel branches are led out from the section of pipeline, a solenoid valve 12 is arranged on one branch, an electronic expansion valve 13, a second liquid storage device 20 and a one-way valve 14 are sequentially arranged on the other branch, and the other ends of the solenoid valve 12 and the one-way valve 14 are connected to a pipeline between an evaporator 16 and a main-path electronic expansion valve 11.
The evaporator air inlet temperature sensor 21 and the evaporator air outlet temperature sensor 22 can be used for measuring the air inlet temperature and the air outlet temperature of the evaporator, and the difference value is the temperature difference of inlet air and outlet air.
The return air temperature sensor 19 can be used to measure the return air temperature.
Example 1
After the heat pump unit is started, the ambient temperature Tw is detected firstly, and when the ambient temperature Tw is larger than the defrosting allowable temperature Ts, the evaporator does not frost at the ambient temperature, and the temperature difference between the inlet air and the outlet air of the evaporator and the current of the fan are not identified.
When the ambient temperature Tw is less than or equal to the defrosting allowable temperature Ts, the unit is marked after operating for 10 minutes, and the temperature difference between inlet air and outlet air is marked first, and because the unit only operates for 10 minutes, the unit does not frost in such a short time, the temperature difference between inlet air and outlet air is marked as a calibration temperature difference and is used as a reference value of a frostless state, and the current of the fan at the moment is marked as a calibration current Ls under the same condition. The current of the fan is normal under the condition of no frost, but the air quantity is slowly reduced along with the thickening of frost, the temperature difference between inlet air and outlet air is reduced along with the thickening of frost, the wind resistance is increased due to the frosting, the power consumption of a fan motor is increased, and the current is increased along with the increase of the frost. The frost formed by the evaporator 16 is continuously thickened along with the lapse of time, and the liquid return is caused due to poor evaporation, and the return air temperature is very low, so the frosting condition can be accurately judged by comparing the temperature difference of inlet and outlet air, the current of a fan and the temperature difference between the return air and the environment, and the specific defrosting method is as follows;
1) after a heat pump unit is started, firstly detecting the ambient temperature Tw, and when the ambient temperature Tw is less than or equal to the defrosting allowable temperature Ts, marking the temperature difference of inlet air and outlet air and the current of a fan as a calibration temperature difference and a calibration current when the heat pump unit runs for 10 minutes;
2) measuring the air inlet and outlet temperature difference again, detecting and calculating the difference T1 between the air inlet and outlet temperature difference and the calibration temperature difference, the difference T2 between the fan current and the calibration current, and detecting the difference T3 between the return air temperature and the environment temperature;
3) if the temperature is more than 5 percent and less than T1 and less than 8 percent, and simultaneously, the temperature is more than 5 percent and less than T2 and less than 8 percent, and simultaneously, the defrosting is carried out after 60 minutes when the temperature is more than 3 ℃ and less than T3 and less than 8 ℃;
if the temperature is more than 8 percent and less than T1 and less than 11 percent, and simultaneously, the temperature is more than 8 percent and less than T2 and less than 11 percent, and simultaneously, the defrosting is carried out after 45 minutes when the temperature is more than 8 ℃ and less than T3 and less than 13 ℃;
if the temperature is more than 11% < T1 and less than or equal to 14%, and the temperature is more than 11% < T2 and less than 14%, and the temperature is more than 13 ℃ and less than T3 and less than 18 ℃, defrosting is carried out after 30 minutes;
if the temperature is more than 14% < T1 and less than 17%, and simultaneously the temperature is more than 14% < T2 and less than 17%, and simultaneously the temperature is more than 18 ℃ and less than T3 and less than 23 ℃, defrosting is carried out within 20 minutes;
defrosting is carried out for 10 minutes if 17% < T1 < 20%, while 17% < T2 < 20%, while 23 deg.C < T3 < 28 deg.C.
Referring to fig. 2, a specific defrosting method is as follows:
s1, detecting the environment temperature Tw after the heat pump unit is started;
s2, calculating the temperature difference of inlet and outlet air, marking the temperature difference as a calibration temperature difference, and marking the current of a fan as a calibration current;
s3, whether the environment temperature Tw is less than or equal to the defrosting allowable temperature Ts;
s4, calculating the difference Tc between the inlet and outlet air temperature difference and the calibration temperature difference after the unit operates for 10 minutes;
s5, judging whether Tc is more than 5%, if so, turning to S6;
s6, judging whether Tc is less than or equal to 8%, if yes, turning to S61, if no, turning to S7;
s61, judging whether the difference value between the fan current and the calibration current is more than 5%, if so, turning to S62;
s62, judging whether the difference value between the fan current and the calibration current is less than 8%, if so, turning to S63;
s63, judging whether the difference between the return air temperature and the ambient temperature is greater than 3 ℃, if so, turning to S64;
s64, judging whether the difference between the return air temperature and the ambient temperature is less than 8 ℃, if so, turning to S65;
s65, defrosting after 60 minutes;
s7, judging whether Tc is less than or equal to 11%, if yes, turning to S71, if no, turning to S8;
s71, judging whether the difference value between the fan current and the calibration current is more than 8%, if so, turning to S72;
s72, judging whether the difference value between the fan current and the calibration current is less than 11%, if so, turning to S73;
s73, judging whether the difference between the return air temperature and the ambient temperature is more than 8 ℃, if so, turning to S74;
s74, judging whether the difference between the return air temperature and the ambient temperature is less than 13 ℃, if so, turning to S75;
s75, defrosting after 45 minutes;
s8, judging whether Tc is less than or equal to 14%, if yes, turning to S81, if no, turning to S9;
s81, judging whether the difference value between the fan current and the calibration current is more than 11%, if so, turning to S82;
s82, judging whether the difference value between the fan current and the calibration current is less than 14 percent, if so, turning to S83;
s83, judging whether the difference between the return air temperature and the ambient temperature is larger than 13 ℃, if so, turning to S84;
s84, judging whether the difference between the return air temperature and the ambient temperature is less than 18 ℃, if so, turning to S85;
s85, defrosting after 30 minutes;
s9, judging whether Tc is less than or equal to 17%, if yes, turning to S91, if no, turning to S10;
s91, judging whether the difference value between the fan current and the calibration current is larger than 14%, if so, turning to S92;
s92, judging whether the difference value between the fan current and the calibration current is less than 17%, if so, turning to S93;
s93, judging whether the difference between the return air temperature and the ambient temperature is greater than 18 ℃, if so, turning to S94;
s94, judging whether the difference between the return air temperature and the ambient temperature is less than 23 ℃, if so, turning to S95;
s95, defrosting after 20 minutes;
s10, judging whether Tc is less than or equal to 20%, if yes, turning to S101;
s101, judging whether the difference value of the fan current and the calibration current is larger than 17%, if so, turning to S102;
s102, judging whether the difference value between the fan current and the calibration current is less than 20%, if so, turning to S103;
s103, judging whether the difference value between the return air temperature and the ambient temperature is greater than 23 ℃, if so, turning to S104;
s104, judging whether the difference value between the return air temperature and the ambient temperature is less than 28 ℃, if so, turning to S105;
and S105, defrosting after 10 minutes.
When the defrosting treatment is carried out, the fan of the evaporator 16 is stopped, the fan of the condenser 4 keeps running, then the electromagnetic valve 12 is opened, high-temperature liquid refrigerant flows to the evaporator 16 from the first liquid reservoir 5, the defrosting is carried out by utilizing the high-temperature liquid refrigerant, the four-way valve does not need to be switched, the temperature of a drying room is not influenced, the temperature of the drying room is kept unchanged after the heat of the condenser 4 is dissipated, at the moment, the medium-temperature refrigerant enters the evaporator 16 for defrosting, and compared with the high-temperature and high-pressure gaseous refrigerant of a hot gas bypass, the method can more effectively protect the compressor and avoid the overhigh temperature of a motor of the compressor, and the method effectively solves the problems and is efficient and energy-saving. At this moment, the temperature difference between the auxiliary road inlet temperature sensor 8 and the auxiliary road outlet temperature sensor 9 is detected, and the temperature difference between the main road inlet temperature sensor 6 and the main road outlet temperature sensor 7 is detected, if the temperature difference of the auxiliary road is too small, the temperature difference of the main road is too large, the enthalpy-increasing electronic expansion valve 10 and the main road electronic expansion valve 11 are closed, a large amount of refrigerant is prevented from flowing away, the stability in the defrosting process is ensured, and the defrosting is more thorough.
When the temperature of the coil pipe is higher than the defrosting exit temperature, the machine exits the defrosting treatment, the electromagnetic valve 12 is closed first, and then the enthalpy-increasing electronic expansion valve 10 and the main-path electronic expansion valve 11 are correspondingly adjusted.
Example 2
The method for adjusting the pressure comprises the steps of detecting the pressure value of the high-pressure sensor 3, opening the electronic expansion valve 13 when the pressure value reaches a set value, guiding the liquid refrigerant of the condenser 4 into the second liquid storage device 20, increasing the heat dissipation area of the condenser 4, keeping the high-pressure stable, measuring the pressure value P detected by the high-pressure sensor, and controlling the logic as follows;
when 40bar is more than P and more than 38bar, the supercooling degree is detected, and if the temperature is higher than 3 ℃ and the supercooling degree is more than 1 ℃, the electronic expansion valve 13 is opened by 30 percent.
When 41bar is more than P and more than 39bar, the supercooling degree is detected, and if the temperature is more than 4 ℃ and the supercooling degree is more than 2 ℃, the electronic expansion valve 13 is opened by 50 percent.
When 42bar is more than P and more than 40bar, the supercooling degree is detected, and if the supercooling degree is more than 5 ℃ and more than 3 ℃, the electronic expansion valve 13 is opened by 70 percent.
When 43bar is more than P and more than 41bar, the supercooling degree is detected, and if the supercooling degree is more than 7 ℃ and more than 4 ℃, the electronic expansion valve 13 is opened by 100 percent.
The supercooling degree is a condensation temperature — a fin outlet temperature, the condensation temperature is a condensation temperature of the liquid refrigerant of the condenser 4, and the fin outlet temperature is a fin outlet temperature of the condenser.
Referring to fig. 3, a specific method is as follows:
s11, detecting the pressure value of the high-pressure sensor;
s12, judging whether the pressure value is larger than 38bar, if so, turning to S13;
s13, judging whether the pressure value is less than 40bar, if so, turning to S131, if not, turning to S14;
s131, judging whether the supercooling degree is more than 1 ℃, if so, turning to S132;
s132, judging whether the supercooling degree is less than 3 ℃, and turning to S133 if the judgment result is yes;
s133, opening the valve of the electronic expansion valve by 30 percent;
s14, judging whether the pressure value is larger than 39bar, if so, turning to S15;
s15, judging whether the pressure value is less than 41bar, if so, turning to S151, and if not, turning to S16;
s151, judging whether the supercooling degree is more than 2 ℃, if so, turning to S152;
s152, judging whether the supercooling degree is less than 4 ℃, if so, turning to S153;
s153, opening the valve of the electronic expansion valve by 50 percent;
s16, judging whether the pressure value is larger than 40bar, if so, turning to S17;
s17, judging whether the pressure value is less than 42bar, if yes, turning to S171, if no, turning to S18;
s171, judging whether the supercooling degree is more than 3 ℃, if so, turning to S172;
s172, judging whether the supercooling degree is less than 5 ℃, if so, turning to S173;
s173, opening the valve of the electronic expansion valve by 70 percent;
s18, judging whether the pressure value is larger than 40bar, if so, turning to S19;
s19, judging whether the pressure value is less than 42bar, if so, turning to S191;
s191, judging whether the supercooling degree is more than 3 ℃, if so, turning to S192;
s192, judging whether the supercooling degree is less than 5 ℃, if so, turning to S193;
and S193, opening the electronic expansion valve by 70 percent.
The system and the method keep the pressure stable and ensure the stability and the reliability of the unit under the condition of not changing the structure and the capacity of the drying room. The method can also record data and analyze the data, if the temperature of the drying room is at the low ring temperature, the pressure reduction function is also triggered, the system can record the data at the moment, and when the temperature exceeds three times, the blockage of the condenser can be displayed, so that a user can be reminded of cleaning the condenser in time. Because when low ring temperature, machine high pressure can not be very high, but when the condenser blockked up, the unable heat dissipation of fan can lead to gaseous refrigerant unable liquefaction like this to lead to the high pressure. The method is easy to obtain by judging the pressure and the supercooling degree, and the method has high pressure and small supercooling degree, thereby judging poor heat dissipation and carrying out corresponding prompt. The stability and the reliability of the machine are ensured, and the intellectualization and the high safety of the machine are highlighted more importantly.
While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (6)
1. A method of defrosting and pressure regulating a heat pump dryer, the method comprising the steps of:
1) after a heat pump unit is started, firstly detecting the ambient temperature Tw, and when the ambient temperature Tw is less than or equal to the defrosting allowable temperature Ts, marking the temperature difference of inlet air and outlet air and the current of a fan as a calibration temperature difference and a calibration current when the heat pump unit runs for 10 minutes;
2) measuring the air inlet and outlet temperature difference again, detecting and calculating the difference T1 between the air inlet and outlet temperature difference and the calibration temperature difference, the difference T2 between the fan current and the calibration current, and detecting the difference T3 between the return air temperature and the environment temperature;
3) if the temperature is more than 5 percent and less than or equal to T1 and less than or equal to 8 percent, and simultaneously, the temperature is more than 5 percent and less than T2 and less than 8 percent, and simultaneously, the defrosting treatment is carried out after 60 minutes when the temperature is more than 3 ℃ and less than T3 and less than 8 ℃;
if the temperature is more than 8 percent and less than T1 and less than 11 percent, and simultaneously, the temperature is more than 8 percent and less than T2 and less than 11 percent, and simultaneously, the defrosting treatment is carried out after 45 minutes when the temperature is more than 8 ℃ and less than T3 and less than 13 ℃;
if the temperature is more than 11 percent and less than T1 and less than 14 percent, and the temperature is more than 11 percent and less than T2 and less than 14 percent, and the temperature is more than 13 ℃ and less than T3 and less than 18 ℃, entering the defrosting treatment after 30 minutes;
if the temperature is more than 14% < T1 and less than or equal to 17%, and simultaneously, the temperature is more than 14% < T2 and less than 17%, and simultaneously, the defrosting treatment is carried out within 20 minutes when the temperature is more than 18 ℃ and less than T3 and less than 23 ℃;
if the temperature is more than 17% < T1 and less than or equal to 20%, and the temperature is more than 17% < T2 and less than 20%, and the temperature is more than 23 ℃ and less than T3 and less than 28 ℃, entering the defrosting treatment within 10 minutes;
the heat pump dryer comprises a heat pump unit; the system comprises a compressor (1), a gas-liquid separator (17) and a four-way valve, wherein a loop is formed by pipelines, the other end of the compressor (1) is connected with an enhanced vapor injection economizer, an auxiliary outlet temperature sensor (9) is connected to the pipeline between the compressor (1) and the enhanced vapor injection economizer, one end of the enhanced vapor injection economizer is connected with a first liquid storage device (5) through the pipeline, a main inlet temperature sensor (6) is arranged on the pipeline, one end of the enhanced vapor injection economizer is connected with an enhanced vapor electronic expansion valve (10) through the pipeline, and an auxiliary inlet temperature sensor (8) is arranged on the pipeline; one end of the enhanced vapor injection economizer is connected with a main electronic expansion valve (11) through a pipeline, and a main outlet temperature sensor (7) is arranged on the pipeline; the other end of the enthalpy-increasing electronic expansion valve (10) is connected to a pipeline between the main outlet temperature sensor (7) and the main electronic expansion valve (11); the other end of the main-path electronic expansion valve (11) is connected with an evaporator (16) through a pipeline, and a coil temperature sensor (15), an evaporator air inlet temperature sensor (21) and an evaporator air outlet temperature sensor (22) are arranged on the evaporator (16); the other end of the evaporator (16) is connected with a four-way valve through a pipeline; one end of the four-way valve is connected with the condenser (4) through a pipeline, the other end of the condenser (4) is connected with the first liquid storage device (5), the other end of the first liquid storage device (5) is connected with a section of pipeline, two parallel branches are led out from the section of pipeline, a solenoid valve (12) is arranged on one branch, an electronic expansion valve (13), a second liquid storage device (20) and a one-way valve (14) are sequentially arranged on the other branch, and the other ends of the solenoid valve (12) and the one-way valve (14) are connected to a pipeline between the evaporator (16) and the main-path electronic expansion valve (11);
the defrosting process comprises the following steps: the fan of the evaporator (16) stops rotating, the fan of the condenser (4) keeps running, the electromagnetic valve (12) is opened, and the high-temperature liquid refrigerant flows to the evaporator (16) from the first liquid reservoir (5).
2. The method for defrosting and regulating pressure of a heat pump dryer according to claim 1, wherein the defrosting process further comprises the steps of: the temperature difference between the auxiliary road inlet temperature sensor (8) and the auxiliary road outlet temperature sensor (9) is detected, the temperature difference between the main road inlet temperature sensor (6) and the main road outlet temperature sensor (7) is detected, and if the auxiliary road temperature difference is too small and the main road temperature difference is too large, the enthalpy-increasing electronic expansion valve (10) and the main road electronic expansion valve (11) are closed.
3. The method for defrosting and pressure regulating of a heat pump dryer according to claim 1, wherein the step of exiting the defrosting process is as follows: when the temperature of the coil pipe is higher than the defrosting exit temperature, the machine exits the defrosting treatment, the electromagnetic valve (12) is closed, and the enthalpy-increasing electronic expansion valve (10) and the main-path electronic expansion valve (11) are correspondingly adjusted.
4. The method for defrosting and adjusting pressure of a heat pump dryer according to claim 1, wherein a pressure value of the high pressure sensor (3) is detected, and when the pressure value reaches a set value, the electronic expansion valve (13) is opened to guide the liquid refrigerant of the condenser (4) into the first accumulator (5) and the second accumulator (20), thereby increasing the heat dissipation area of the condenser (4).
5. The method for defrosting and pressure regulating of a heat pump dryer according to claim 4, wherein the electronic expansion valve control method comprises the steps of:
1) measuring a pressure value P detected by the high-pressure sensor;
2) when 40bar is more than P and more than 38bar, if the temperature is more than 3 ℃ and the supercooling degree is more than 1 ℃, the electronic expansion valve is opened by 30 percent;
when 41bar is more than P and more than 39bar, if 4 ℃ is more than supercooling degree and more than 2 ℃, the electronic expansion valve is opened by 50 percent;
when 42bar is more than P and more than 40bar, if the temperature is more than 5 ℃ and the supercooling degree is more than 3 ℃, the electronic expansion valve is opened by 70 percent;
when 43bar is more than P and more than 41bar, and when 7 ℃ is more than supercooling degree and more than 4 ℃, the electronic expansion valve opens 100 percent.
6. The method for defrosting and pressure regulating of a heat pump dryer according to claim 5, wherein the degree of supercooling is a condensation temperature-fin outlet temperature, the condensation temperature is a condensation temperature of a liquid refrigerant of the condenser (4), and the fin outlet temperature is a fin outlet temperature of the condenser.
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