CN113865005B - Defrosting shunting method - Google Patents
Defrosting shunting method Download PDFInfo
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- CN113865005B CN113865005B CN202111267011.2A CN202111267011A CN113865005B CN 113865005 B CN113865005 B CN 113865005B CN 202111267011 A CN202111267011 A CN 202111267011A CN 113865005 B CN113865005 B CN 113865005B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F11/41—Defrosting; Preventing freezing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F1/00—Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station
- F24F1/0003—Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station characterised by a split arrangement, wherein parts of the air-conditioning system, e.g. evaporator and condenser, are in separately located units
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/65—Electronic processing for selecting an operating mode
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/72—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure
- F24F11/74—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity
- F24F11/77—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity by controlling the speed of ventilators
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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
- F25B41/00—Fluid-circulation arrangements
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
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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
- F25B41/00—Fluid-circulation arrangements
- F25B41/30—Expansion means; Dispositions thereof
- F25B41/31—Expansion valves
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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
- F25B41/00—Fluid-circulation arrangements
- F25B41/40—Fluid line arrangements
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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
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
- F25D21/06—Removing frost
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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
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
Abstract
The invention provides a defrosting and shunting method, which is used for shunting a refrigerant of an outdoor heat exchanger in an air conditioning system, and comprises the following steps: determining a heat exchange difference value delta k between the maximum heat exchange coefficient and the minimum heat exchange coefficient of an outdoor heat exchange tube of the outdoor heat exchanger and the tube length L of the outdoor heat exchange tube; judging the frost formation amount or the difference of the heat exchange amount along the pipeline flowing direction of the outdoor heat exchange pipe according to the heat exchange difference value delta k and the pipe length L so as to determine the number n of bypass branches communicated with the outdoor heat exchange pipe; one end of the bypass branch is communicated with an outlet of the air conditioning system, and the other end of the bypass branch is communicated with the middle part of the outdoor heat exchange tube; n is an integer greater than or equal to 0, so that the problem of low defrosting efficiency of the air conditioner in the prior art is solved.
Description
Technical Field
The invention relates to an air conditioning system, in particular to a defrosting and shunting method.
Background
The frosting problem of the air-cooled heat exchanger is a key problem which restricts the popularization and application of the air source heat pump air conditioner in low-temperature and high-humidity areas in winter. When a user uses the air conditioner to heat in winter, the outdoor heat exchanger absorbs heat from outdoor air and supplies the heat to the indoor, and when the outdoor environment temperature is lower than 7 ℃ and the relative humidity is higher than 50%, the heat exchanger frosts. As the frost layer becomes thicker, the thermal resistance of the outdoor heat exchanger increases, the heat exchange efficiency decreases, the heating capacity of the air conditioner significantly decreases, and the operation energy efficiency decreases, so that defrosting needs to be performed at regular time to improve the energy efficiency of the air conditioner. Along with the increasing demand of heat pump air-conditioning heating, the problems of heat efficiency and comfort caused by frequent defrosting of the air-conditioning in low-temperature and high-humidity areas become more and more prominent, and a set of efficient and comfortable defrosting technology is urgently needed in the industry.
The defrosting technology of the heat exchanger can be roughly divided into thermal defrosting and non-thermal defrosting, wherein the thermal defrosting can be divided into in-pipe heat exchange defrosting and out-pipe heat exchange defrosting according to the heat exchange mode. In the defrosting process, part of heat supply of the heat source is dissipated to low-temperature outdoor air, and the part of heat does not directly act on a frost layer, so that the heat is defined as invalid heat consumption of the system, and the thermal defrosting air-conditioning system has certain defrosting efficiency (or system defrosting heat utilization rate).
The heat defrosting mode of the existing heat exchanger is various, and the heat defrosting mode can be divided into near air side heat exchange defrosting and near tube side heat exchange defrosting according to the heat absorption and melting direction of a frost layer. The external heat exchange defrosting (such as infrared defrosting or electric heating defrosting) is used as an auxiliary device of an air conditioning system, can provide enough heat for quick defrosting of the near air side of a frost layer, but the heat dissipated to outdoor air by the system is also large, the utilization rate of defrosting heat is low, and meanwhile, the safety and reliability problems exist.
For the in-tube heat exchange defrosting mode (such as conventional reverse cycle defrosting, hot gas bypass defrosting, heat storage defrosting and the like), defrosting heat directly acts on the near-tube side of a frost layer and is transmitted to the air side, theoretically, the heat dissipated to the air side is relatively small, defrosting efficiency is relatively high, but the defrosting heat is limited by the reliability of an air conditioning system, the defrosting heat of the system is limited, generally, the defrosting heat is only 1/4 to 1/3 or even less of normal heating, the defrosting heat is gradually attenuated along the flowing direction of a refrigerant in a tube, and defrosting asynchronization occurs in each tube section, so that defrosting time in the practical application process is long, part of the tube sections are dried and burned in the defrosting process, the heat is dissipated to outdoor air, and defrosting efficiency is reduced.
For the thermal defrosting mode of the heat exchanger, in addition to the reason that the defrosting efficiency is low due to the heat supply mode of the heat source in the defrosting process, the phenomenon of uneven frosting in the frosting process of the outdoor heat exchanger is also one of important reasons for influencing the defrosting efficiency. In the normal heating process, along the flowing direction of the refrigerant in the pipe, the heat absorption capacity of outdoor air of the outdoor heat exchanger is generally gradually attenuated, the frosting capacity of the heat exchanger is also gradually reduced, and meanwhile, the frosting capacity is generally uneven due to the influence of the air flow rate outside the pipe and the temperature/humidity difference of different pipe sections. Under the double influences of uneven frosting amount distribution and uneven defrosting heat distribution of the air source heat pump air conditioner, the defrosting efficiency is greatly reduced, and the system energy loss caused by the defrosting of the air conditioner is huge.
It can be seen that the prior art defrosting method has at least the following problems:
the defrosting heat is increased and the defrosting speed is increased by various technical means, but the utilization rate of the defrosting heat is still low, and the expected improvement effect is difficult to achieve. If the conventional reverse cycle defrosting is adopted, the heating is switched into the cooling operation during the defrosting, the energy loss is large in the switching process, the problem that the frosting and defrosting of the heat exchanger are not synchronous is not solved, the defrosting heat utilization rate is low, and meanwhile, the indoor heat is absorbed and used for defrosting of the outdoor heat exchanger, so that the indoor temperature drop is greatly reduced, and the thermal comfort of a human body is reduced.
The structure and the control method for improving the defrosting rate by performing bypass defrosting on a heat exchanger in the prior art solve the problem of low defrosting efficiency caused by uneven defrosting amount, but because the parameters of the heat exchanger change in real time during defrosting, and the positions of bypass shunts are fixed, on the premise that the corresponding relation between the resistance flow of a pipe network and the real-time change of the defrosting amount of each pipe section is not established, the synchronous defrosting effect of each pipe section of the heat exchanger is relatively poor, and the expected defrosting efficiency improving effect is difficult to achieve.
Disclosure of Invention
The invention mainly aims to provide a defrosting shunting method to solve the problem that the defrosting efficiency of an air conditioner in the prior art is low.
To achieve the above objects, according to one aspect of the present invention, there is provided a defrosting shunt method for cooling an outdoor heat exchanger in an air conditioning systemThe medium is shunted, and the defrosting shunting method comprises the following steps: determining a heat exchange difference value delta k between the maximum heat exchange coefficient and the minimum heat exchange coefficient of an outdoor heat exchange tube of the outdoor heat exchanger and the tube length L of the outdoor heat exchange tube; judging the frost formation amount or the difference of the heat exchange amount along the pipeline flowing direction of the outdoor heat exchange pipe according to the heat exchange difference value delta k and the pipe length L so as to determine the number n of bypass branches communicated with the outdoor heat exchange pipe; one end of the bypass branch is communicated with an outlet of the air conditioning system, and the other end of the bypass branch is communicated with the middle part of the outdoor heat exchange tube; n is an integer greater than or equal to 0; the method for determining the number n of the bypass branches communicated with the outdoor heat exchange pipe comprises the following steps: when the delta k is smaller than a first preset heat exchange coefficient k 1 Then, the actual length L of the outdoor heat exchange tube and the first preset length L of the outdoor heat exchange tube are judged 1 The magnitude relationship between them; when the actual pipe length L is less than or equal to the first preset pipe length L 1 When, take n =0; when the delta k is more than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 Then, the actual length L and the second preset length L of the outdoor heat exchange tube are judged 2 The magnitude relationship between them; second preset pipe length L 2 Is less than the first preset pipe length L 1 (ii) a When the actual pipe length L is less than or equal to the second preset pipe length L 2 When n =0; otherwise, according to the actual tube length L and the first preset heat exchange coefficient k 1 Obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube, and obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube according to the actual tube length L and a second preset heat exchange coefficient k 2 Obtaining the maximum value of the bypass branches communicated with the outdoor heat exchange tube, and determining the number n of the bypass branches according to the delta k; when delta k is larger than a second preset heat exchange coefficient k 2 When the heat exchange pipe section is divided into a first heat exchange pipe section and a second heat exchange pipe section, and the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section is smaller than k 2 (ii) a And judging the number n of bypass branches communicated with the shunting of the first heat exchange pipe section and the second heat exchange pipe section respectively according to the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section and the length of the pipe sections.
Further, the defrosting diversion method further comprises the following steps: and determining the heat exchange coefficient k of each position of each outdoor heat exchange tube of the outdoor heat exchanger according to the parameters of the outdoor heat exchanger so as to determine the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tubes.
Further, after determining the heat exchange coefficient k of each position of each outdoor heat exchange tube, the defrosting shunting method further comprises the following steps: drawing a heat exchange coefficient k-x curve of the corresponding outdoor heat exchange tube; determining the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tube according to the heat exchange coefficient k-x curve; in the heat exchange coefficient k-x curve, the origin of coordinates is a refrigerant inlet point when the air conditioning system is in heating operation, the abscissa x represents the tube length of the outdoor heat exchange tube, the direction of the abscissa x is the flowing direction of the refrigerant in the outdoor heat exchange tube, and the ordinate k represents the heat exchange coefficient k.
Further, after determining the number n of bypass branches, the defrost diversion method further includes: determining the ratio of frosting amount of a plurality of heat exchange tube sections of the outdoor heat exchange tube after the outdoor heat exchange tube is divided by the n bypass branches according to the flow resistance of the n bypass branches; and determining the position of a bypass node of the outdoor heat exchange pipe for communicating with the bypass branch according to the heat exchange quantity of each position of the outdoor heat exchange pipe along the flowing direction of the refrigerant and the ratio of the frosting quantities of the plurality of heat exchange pipe sections.
Further, the defrosting diversion method further comprises the following steps: when the air conditioning system is in a heating mode, calculating the heat exchange quantity of each position of the outdoor heat exchange tube along the flowing direction of the refrigerant; and according to the heat exchange quantity of each position of the outdoor heat exchange tube along the flowing direction of the refrigerant, obtaining the circulation resistance of the n bypass branches.
Further, after obtaining the heat exchange amount of each position of the outdoor heat exchange tube along the refrigerant flowing direction, the defrosting and shunting method further comprises the following steps: and acquiring an M-x distribution curve of the frosting amount M along the tube length direction of the outdoor heat exchange tube, and determining the position of a bypass node of the outdoor heat exchange tube according to the M-x distribution curve and the ratio of the frosting amounts of a plurality of heat exchange tube sections.
Further, the method for determining the number n of the bypass branches communicated with the outdoor heat exchange pipe comprises the following steps: when the delta k is smaller than a first preset heat exchange coefficient k 1 Then, the actual length L and the first preset length L of the outdoor heat exchange tube are judged 1 The magnitude relationship between them; when the actual pipe length L is less than or equal to the first preset pipe length L 1 When n =0.
Further, the method for determining the number n of the bypass branches communicated with the outdoor heat exchange pipe comprises the following steps: when the delta k is more than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 Then, the actual length L and the second preset length L of the outdoor heat exchange tube are judged 2 The magnitude relationship between them; second predetermined tube length L 2 Is less than the first preset pipe length L 1 (ii) a When the actual pipe length L is less than or equal to the second preset pipe length L 2 When, take n =0; otherwise, according to the actual tube length L and the first preset heat exchange coefficient k 1 Obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube, and obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube according to the actual tube length L and a second preset heat exchange coefficient k 2 And obtaining the maximum value of the bypass branches communicated with the outdoor heat exchange tube, and determining the number n of the bypass branches according to the delta k.
Further, the method for determining the number n of the bypass branches communicated with the outdoor heat exchange pipe comprises the following steps: when delta k is larger than a second preset heat exchange coefficient k 2 When the heat exchange pipe section is divided into a first heat exchange pipe section and a second heat exchange pipe section, and the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section is smaller than k 2 (ii) a And judging the number n of bypass branches communicated with the shunting of the first heat exchange pipe section and the second heat exchange pipe section respectively according to the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section and the length of the pipe sections.
By applying the technical scheme of the invention, the defrosting shunting method provided by the invention comprises the following steps: determining a heat exchange difference value delta k between the maximum heat exchange coefficient and the minimum heat exchange coefficient of an outdoor heat exchange tube of the outdoor heat exchanger and the tube length L of the outdoor heat exchange tube; judging the frost formation amount or the difference of the heat exchange amount along the pipeline flowing direction of the outdoor heat exchange pipe according to the heat exchange difference value delta k and the pipe length L so as to determine the number n of bypass branches communicated with the outdoor heat exchange pipe; one end of the bypass branch is communicated with an outlet of the air conditioning system, and the other end of the bypass branch is communicated with the middle part of the outdoor heat exchange tube; n is an integer greater than or equal to 0. Therefore, the defrosting and shunting method determines the number of the bypass branches to shunt the refrigerant of the outdoor heat exchanger in the air conditioning system, so that all heat exchange pipe sections of the indoor heat exchange pipe of the outdoor heat exchanger can be defrosted synchronously, and the problems of poor synchronous defrosting effect and low defrosting efficiency in the prior art are solved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiment(s) of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 illustrates a schematic diagram of an efficient defrost air conditioning system according to an embodiment of the air conditioning system of the present invention;
FIG. 2 is a schematic view illustrating a defrosting heating diverging structure and a diverging position thereof according to an embodiment of an air conditioning system of the present invention;
fig. 3 shows a method of designing the number of bypass branch lines according to an embodiment of the defrosting division method of the present invention.
Wherein the figures include the following reference numerals:
1. a compressor; 2. an outdoor heat exchanger; 20. an outdoor heat exchange pipe; 200. a heat exchange tube section; 201. a first heat exchange tube section; 202. a second heat exchange tube section; 210. a bypass node; 3. an indoor heat exchanger; 4. a temperature sensing member; 100. a refrigerant circulation line; 101. a bypass branch; 5. a first expansion valve; 6. a second expansion valve; 7. a bypass control valve; 8. a refrigerant control valve.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Referring to fig. 3, the present invention provides a defrosting shunting method for shunting a refrigerant of an outdoor heat exchanger 2 in an air conditioning system, the defrosting shunting method including: determining outdoor changesA heat exchange difference delta k between the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tube 20 of the heat exchanger 2, and a tube length L of the outdoor heat exchange tube 20; judging the difference of the frost formation amount or the heat exchange amount along the pipeline flowing direction of the outdoor heat exchange pipe 20 according to the heat exchange difference value delta k and the pipe length L so as to determine the number n of the bypass branches 101 communicated with the outdoor heat exchange pipe 20; one end of the bypass branch 101 is communicated with an outlet of the air conditioning system, and the other end of the bypass branch 101 is communicated with the middle part of the outdoor heat exchange tube 20; n is an integer greater than or equal to 0; the method for determining the number n of the bypass branches communicated with the outdoor heat exchange pipe comprises the following steps: when the delta k is smaller than a first preset heat exchange coefficient k 1 Then, the actual length L and the first preset length L of the outdoor heat exchange tube are judged 1 The magnitude relationship between them; when the actual pipe length L is less than or equal to the first preset pipe length L 1 When n =0; when the delta k is more than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 Then, the actual length L and the second preset length L of the outdoor heat exchange tube are judged 2 The magnitude relationship between them; second preset pipe length L 2 Is less than the first preset pipe length L 1 (ii) a When the actual pipe length L is less than or equal to the second preset pipe length L 2 When n =0; otherwise, according to the actual tube length L and the first preset heat exchange coefficient k 1 Obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube, and according to the actual tube length L and a second preset heat exchange coefficient k 2 Obtaining the maximum value of the bypass branches communicated with the outdoor heat exchange tube, and determining the number n of the bypass branches according to the delta k; when delta k is larger than a second preset heat exchange coefficient k 2 When the heat exchange tube section is divided into a first heat exchange tube section and a second heat exchange tube section, and the maximum heat exchange coefficient difference value of the first heat exchange tube section and the second heat exchange tube section is smaller than k 2 (ii) a And judging the number n of bypass branches communicated with the shunting of the first heat exchange pipe section and the second heat exchange pipe section respectively according to the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section and the length of the pipe sections.
The defrosting shunting method provided by the invention comprises the following steps: determining the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tube 20 of the outdoor heat exchanger 2The heat exchange difference Δ k between the thermal coefficients and the tube length L of the outdoor heat exchange tube 20; judging the frost formation amount or the difference of the heat exchange amount along the pipeline flowing direction of the outdoor heat exchange pipe 20 according to the heat exchange difference value delta k and the pipe length L so as to determine the number n of the bypass branches 101 communicated with the outdoor heat exchange pipe 20; one end of the bypass branch 101 is communicated with an outlet of the air conditioning system, and the other end of the bypass branch 101 is communicated with the middle part of the outdoor heat exchange tube 20; n is an integer greater than or equal to 0; the method for determining the number n of the bypass branches communicated with the outdoor heat exchange pipe comprises the following steps: when the delta k is smaller than a first preset heat exchange coefficient k 1 Then, the actual length L and the first preset length L of the outdoor heat exchange tube are judged 1 The magnitude relationship between them; when the actual pipe length L is less than or equal to the first preset pipe length L 1 When, take n =0; when the delta k is more than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 Then, the actual length L and the second preset length L of the outdoor heat exchange tube are judged 2 The magnitude relationship between them; second predetermined tube length L 2 Is less than the first preset pipe length L 1 (ii) a When the actual pipe length L is less than or equal to the second preset pipe length L 2 When, take n =0; otherwise, according to the actual tube length L and the first preset heat exchange coefficient k 1 Obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube, and obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube according to the actual tube length L and a second preset heat exchange coefficient k 2 Obtaining the maximum value of the bypass branches communicated with the outdoor heat exchange tube, and determining the number n of the bypass branches according to the delta k; when delta k is larger than a second preset heat exchange coefficient k 2 When the heat exchange tube section is divided into a first heat exchange tube section and a second heat exchange tube section, and the maximum heat exchange coefficient difference value of the first heat exchange tube section and the second heat exchange tube section is smaller than k 2 (ii) a And judging the number n of bypass branches communicated with the shunting of the first heat exchange pipe section and the second heat exchange pipe section respectively according to the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section and the length of the pipe sections. In this way, the number of the bypass branches 101 is determined by the defrosting and shunting method of the present invention to shunt the refrigerant of the outdoor heat exchanger 2 in the air conditioning system, so that the heat exchange tube segments 200 of the outdoor heat exchange tube 20 of the outdoor heat exchanger 2 can be synchronizedAnd defrosting is carried out, so that the problems of poor synchronous defrosting effect and low defrosting efficiency in the prior art are solved.
In the embodiment of the present invention, the heat exchange coefficient k of each position of each outdoor heat exchange tube 20 of the outdoor heat exchanger 2 is determined according to the parameter of the outdoor heat exchanger 2, so as to determine the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tube 20.
Specifically, according to the pipe diameter D, the pipe length L, the pipe fin ratio and the surface wind speed v of the single outdoor heat exchange pipe 20 of the outdoor heat exchanger 2 x The distribution and other parameters of the single tube are used for confirming the heat exchange coefficient k of the single tube, and a k-x curve is drawn.
Because the outer side of the outdoor heat exchange tube 20 exchanges heat with air and the inner side of the outdoor heat exchange tube 20 exchanges heat with a refrigerant, the heat exchange processes are both phase change convection heat exchange processes, and the specific numerical value of the heat exchange coefficient k can obtain a theoretical solution by utilizing the nussel theory, but is difficult to apply in practical engineering. Therefore, the inner side of the tube can be subjected to linear analysis to obtain the convective heat transfer coefficient h of the inner surface i Approximate solution, the convection heat transfer coefficient h of the outer surface is obtained by the outer side of the tube according to the difference of the surface wind speed distribution of the heat exchanger o 。
In the case of the present example of the invention,
for the same heat exchanger, the convection heat transfer coefficient h of the inner surface i The difference of (a) is related to the dryness fraction χ, i.e. h, of the main refrigerant i =f(χ);
For the same heat exchanger, the convective heat transfer coefficient h of the outer surface o Mainly related to the wind speed v on the outer surface of the heat exchanger x In connection with, i.e. h o =f(v x );
The calculation expression of the single-tube heat exchange coefficient k is as follows:
in the formula (d) o Is the outer diameter of the heat exchange tube d i The inner diameter of the heat exchange tube is shown, and the lambda is the heat conductivity coefficient of the copper tube. In the actual design process, the difference of the heat exchange amount is indirectly judged by detecting the tube temperature at different positions of the tube section.
In the practice of the embodiments of the present inventionIn the middle, the design principle of the number of the bypass branches 101 aims to ensure that the heat exchange of each heat exchange pipe section 200 of the outdoor heat exchanger 2 is sufficient and rapid, and the maximum allowable number of the bypass branches of the air conditioning system is assumed to be n max The minimum number of bypass branches is n min Then, the following conditions are present:
1) If n is greater than n max That is, the number of the bypass branches 101 of the air conditioning system is too large, and when the total flow of the refrigerant of the air conditioning system is limited, the flow of each bypass branch 101 is small, the on-way pressure loss and the local pressure loss of the system increase, and the heat loss of the defrosting bypass structure is too large, which is not beneficial to improving the defrosting efficiency. In addition, the insufficient defrosting heat exchange of part of the bypass branch 101 and the excessive heat at the outlet of the bypass branch 101 have an excessive influence on the heat of other bypass branches 101, so that the defrosting heat is difficult to control and distribute, and the defrosting is asynchronous.
2) If n is less than n min That is, the number of the bypass branches 101 of the air conditioning system is too small, the adjustment range for adjusting the flow rate of each bypass branch 101 through the valve is limited, and when the flow rate of each bypass branch 101 is adjusted to the maximum value, at least one bypass branch 101 is seriously out of synchronization with the other bypass branches 101 (the difference of defrosting time t is more than t) 1 ) And the defrosting split-flow structure has poor defrosting efficiency improving effect.
Therefore, the number n of bypass branches 101 should be controlled to be [ n ] min ，n max ]In which n is min 、n max The heat exchange coefficient k value curve of different positions of each heat exchange pipe section 200 of the outdoor heat exchanger 2 is combined with the maximum/minimum k value difference, the pipe diameter D and the pipe length L to determine.
In an embodiment of the present invention, after determining the heat exchange coefficient k of each position of each outdoor heat exchange pipe 20, the air conditioning control method further includes: drawing a heat exchange coefficient k-x curve of the corresponding outdoor heat exchange tube 20; determining the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tube 20 according to the heat exchange coefficient k-x curve; in the heat exchange coefficient k-x curve, the origin of coordinates is a refrigerant inlet point when the air conditioning system is in heating operation, the abscissa x represents the tube length of the outdoor heat exchange tube 20, the direction of the abscissa x is the flowing direction of the refrigerant in the outdoor heat exchange tube 20, and the ordinate k represents the heat exchange coefficient k.
Specifically, the origin of coordinates is an inlet point of the refrigerant before the refrigerant flows into the outdoor heat exchanger 2.
In the specific implementation process of the embodiment of the invention, a k-x curve is calculated according to the heat exchange coefficient curve, and the maximum heat exchange coefficient difference is obtained as k = k max -k min The corresponding position and distance are judged, and the tube length L and the first preset heat exchange coefficient k 1 A second predetermined heat transfer coefficient k 2 Value, first preset tube length L 1 The value, and thus the number of bypass branches 101.
In an embodiment of the present invention, the method for determining the number n of the bypass branches 101 communicating with the outdoor heat exchange pipe 20 comprises: when the delta k is smaller than a first preset heat exchange coefficient k 1 Then, the actual tube length L and the first predetermined tube length L of the outdoor heat exchange tube 20 are determined 1 The magnitude relationship between them; when the actual pipe length L is less than or equal to the first preset pipe length L 1 When n =0.
Specifically, when the delta k is smaller than a first preset heat exchange coefficient k 1 In the meantime, the heat exchange coefficient heat exchange difference between the positions of the heat exchange pipe sections 200 of the outdoor heat exchanger 2 is not great, and therefore, the actual pipe length L and the first preset pipe length L are continuously judged at this time 1 The relationship (2) of (c). When the actual pipe length L is less than or equal to the first preset pipe length L 1 Meanwhile, the length of a single outdoor heat exchange tube 20 of the outdoor heat exchanger 2 is short, the difference between the synchronicity of the defrosting by adopting bypass flow division and the original system flow is small, the defrosting of each section is synchronous, and therefore n =0 is taken; when the actual pipe length L is larger than the first preset pipe length L 1 In the process, the length of a single outdoor heat exchange tube 20 of the outdoor heat exchanger 2 is long, the difference of frost formation amount of each section along the length direction of the tube is large, and the number n of the bypass branch paths is directly determined according to the length L of the actual tube.
In an embodiment of the present invention, the method for determining the number n of the bypass branches 101 communicating with the outdoor heat exchange pipe 20 comprises: when the delta k is more than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 Then, the actual tube length L and the second predetermined tube length L of the outdoor heat exchange tube 20 are determined 2 The magnitude relationship between them; second onePreset pipe length L 2 Is less than the first preset pipe length L 1 (ii) a When the actual pipe length L is less than or equal to the second preset pipe length L 2 During defrosting, defrosting of each section is synchronous, bypass shunting is not carried out, and n =0 is selected; otherwise, according to the actual tube length L and the first preset heat exchange coefficient k 1 Obtaining the minimum number of the bypass branch 101 communicated with the outdoor heat exchange pipe 20 and according to the actual pipe length L and the second preset heat exchange coefficient k 2 The maximum value of the bypass branch 101 communicated with the outdoor heat exchange pipe 20 is obtained, and the number n of the bypass branch 101 is determined according to delta k.
Specifically, when Δ k is greater than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 When the difference of heat exchange coefficients of all positions of the heat exchanger is large, the difference of frost formation amount is large, and the pipe length L and the preset pipe length L are continuously judged 2 Of size (c), wherein, L 2 Less than L 1 The more the outdoor heat exchange tube 20 is divided into the heat exchange tube segments 200, the greater the difference of the heat exchange coefficient k, and the more bypass flow division is required.
Specifically, the method for determining the number n of the bypass branches 101 communicated with the outdoor heat exchange pipe 20 comprises the following steps: when delta k is larger than a second preset heat exchange coefficient k 2 In the meantime, the heat exchange tube section 200 is divided into a first heat exchange tube section 201 and a second heat exchange tube section 202, and the maximum heat exchange coefficient difference values of the first heat exchange tube section 201 and the second heat exchange tube section 202 are smaller than k 2 (ii) a The number n of bypass legs 101 in split communication with the first and second heat exchange tube sections 201, 202, respectively, is determined based on the maximum heat exchange coefficient difference and the length of the tube sections for the first and second heat exchange tube sections 201, 202, respectively.
In the embodiment of the invention, when the Δ k is too large, the capacity of the outdoor heat exchanger 2 is seriously uneven, and the outdoor heat exchanger 2 is optimally adjusted.
Further, after determining the number n of the bypass branch 101, the defrosting diversion method further includes: determining the ratio of frosting amount of the plurality of heat exchange tube sections 200 after the outdoor heat exchange tube 20 is shunted according to the flow resistance of the n bypass branches 101; the bypass node position of the outdoor heat exchange pipe 20 is determined according to the magnitude of the heat exchange amount at each position of the outdoor heat exchange pipe 20 in the refrigerant flowing direction and the ratio of the frost formation amounts of the plurality of heat exchange tube sections 200.
When the air conditioning system is in a heating mode, calculating the heat exchange quantity of each position of the outdoor heat exchange pipe 20 along the flowing direction of the refrigerant; the flow resistances of the n bypass branches 101 are obtained according to the heat exchange amount of each position of the outdoor heat exchange tube 20 along the refrigerant flowing direction.
Specifically, after obtaining the heat exchange amount of each position of the outdoor heat exchange tube 20 along the refrigerant flowing direction, the defrosting shunting method further includes: an M-x distribution curve of the frost formation amount M along the tube length direction of the outdoor heat exchange tube 20 is obtained to determine the position of the bypass node 210 of the outdoor heat exchange tube 20 according to the M-x distribution curve and the ratio of the frost formation amounts of the plurality of heat exchange tube sections 200.
Specifically, taking a bypass (n = 1) as an example, as shown in fig. 1 and fig. 2, a defrosting heat supply shunting structure and a shunting position thereof are illustrated. The bd section is a plan view of a single heat exchange tube section 200 of the outdoor heat exchanger 2. The abcd section in the figure represents the hot air defrosting process of the original system of the air conditioner: the method comprises the following steps that exhaust air of a compressor 1 of the air conditioner passes through an indoor heat exchanger 3, a fan of the indoor heat exchanger 3 is closed, and then enters an outdoor heat exchanger 2 from a refrigerant inlet of the outdoor heat exchanger 2 through a first expansion valve 5 to defrost, wherein the opening degree of the first expansion valve 5 is opened to the maximum; or the hot gas defrosting process is that the compressor 1 exhausts gas and then directly enters the outdoor heat exchanger 2 without passing through the indoor heat exchanger 3.
The aec section is shown as a defrosting bypass branch 101, and the defrosting bypass branch 101 includes a set of valves, such as a bypass control valve 7 and a second expansion valve 6, for controlling the opening and closing of the bypass branch 101 and flow rate adjustment, and the exhaust gas of the compressor 1 enters a point c in the outdoor heat exchanger 2 through the bypass branch 101, is mixed with the main flow path of the refrigerant circulation pipeline 100, and then enters a cd pipe section for defrosting. The heat exchange tube section 200 of the outdoor heat exchanger 2 is divided into n +1 sections according to the number of nodes of the bypass branch 101, and each heat exchange tube section 200 is provided with a tube temperature sensing bulb representing the average temperature of the section, such as two temperature sensing parts 4 shown in fig. 1.
Preferably, the bypass control valve 7 is a two-way valve.
The node position of the bypass branch 101 is determined according to the resistance flow of the air conditioning system pipe network and the frosting amount of the outdoor heat exchanger 2, and the specific determination method is shown in fig. 3:
(1) calculating the heat exchange quantity of the tube length of each unit outdoor heat exchange tube 20 along the flowing direction of the refrigerant when the air conditioner normally heats according to the heat exchange coefficient k-x curve;
(2) estimating an M-x distribution curve of the frosting amount M along the length direction of the pipe according to the difference of the heat exchange amount;
(3) according to the parameters of the valve and the pipeline, calculating the on-way resistance h of each parallel branch (such as abc section and aec section in figure 1) f Local resistance h j Size, listing the maximum resistance h of each bypass branch 101 max With a minimum resistance h min ；
In particular, the on-way resistance h f The method is calculated according to the state of a refrigerant and the pipe diameter of a heat exchange pipe, and is embodied as refrigerant pressure loss; local resistance h j The number of valves, the valve structure, and the valve opening degree of the bypass branch 101 are different.
Wherein, the on-way resistance h is the same when the refrigerant state is the same f The minimum opening and the maximum opening of the valve correspond to the maximum resistance h max And minimum resistance h min 。
In an embodiment of the invention, the on-way resistance h of each parallel branch (e.g. abc segment, aec segment of fig. 1) f Local resistance h j The method comprises the following specific steps:
the resistance of each heat exchange tube segment 200 through which the bypass branch 101 flows includes an on-way resistance h f And local resistance h j The values are respectively related to a dimensionless on-way resistance coefficient lambda and a dimensionless local resistance coefficient xi. For a segment of a pipe that is in turbulent flow, λ can be calculated by:
the on-way resistance calculation formula of the pipe section can be expressed as:
wherein σ is the equivalent absolute roughness of the tube wall; d is the equivalent inner diameter of the pipe section; sigma/d is the relative roughness of the pipe section; re d The Reynolds number of the refrigerant fluid; l is the total length of the heat exchange tube section 200 through which the bypass branch 101 flows; v is the fluid characteristic flow velocity, and m/s and rho are the density of the refrigerant in the heat exchange tube section.
The dimensionless local drag coefficient ξ may be retrieved from a related manual or supplied by the manufacturer. The pressure loss of the equipment can be greatly changed due to different models, and the provided estimated value can be used for replacing the pressure loss in the calculation. The local resistance of the valve can be expressed as:
(4) according to the resistance of each bypass branch 101, the refrigerant flow ratio m of each bypass branch 101 is calculated 0 ：m 1 （m 0 Represents the original system flow path, m 1 Represents the 1 st bypass branch);
the resistance pressure drop of each bypass branch 101 of the pipe network conforms to kirchhoff's law, namely the flow losses in each bypass branch 101 of the parallel pipelines are the same, namely the pressure drops are the same, and the flow of each bypass branch 101 is determined by the resistance coefficient of the branch. For example, a system having 2 branches then has
In the above formula, λ 1 Through a first bypass branchDimensionless coefficient of on-way resistance, λ, of the first heat exchanger tube section 2 Dimensionless on-way drag coefficient, L, of the second heat exchange tube section through which the second bypass branch flows 1 Is the tube length, L, of the first heat exchange tube section 2 Is the tube length, xi, of the second heat exchange tube section 1 Is a dimensionless local resistance coefficient, ξ, of the first heat exchange tube segment 2 Is a dimensionless local resistance coefficient, v, of the second heat exchange tube section 1 Is the characteristic flow velocity, v, of the fluid in the first heat exchange tube section 2 The characteristic flow rate of the fluid in the second heat exchange tube section is ρ, which is the density of the refrigerant in the outdoor heat exchange tube 20.
A is the cross-sectional area of the outdoor heat exchange tube, A 1 Cross-sectional area, A, of the heat exchange tube section through which the first bypass branch flows 2 Cross-sectional area, p, of the heat exchange tube section through which the second bypass branch flows in Is the pressure, p, of the refrigerant flowing into the bypass branch out Is the pressure when the refrigerant flows out of the bypass branch, and alpha is a kinetic energy correction coefficient and is related to the velocity distribution of the pipe; v. of in Speed, v, of refrigerant flow into bypass branch out Is the speed of refrigerant flowing out of the bypass branch, g is the gravitational acceleration, z in Is potential energy z of refrigerant flowing into the bypass branch out The potential energy is the potential energy when the refrigerant flows out of the bypass branch, rho gz is the potential energy term, and the gas flowing in the heat exchange pipe can be ignored; h is the pressure, p is the pressure loss along the course and the local pressure, p = ρ g (H) f +h j ) Δ gH- Δ p is the actual pressure difference in the outdoor heat exchange tube 20; in denotes a point a where the refrigerant flows in, and out denotes a point c where the refrigerant flows out.
(5) And determining the ratio of the frosting amount of each heat exchange pipe section 200 after the outdoor heat exchanger 2 is shunted according to the ratio of the refrigerant flow, and combining an M-x distribution curve to obtain the design position of the bypass node of the outdoor heat exchanger 2.
In the embodiment of the present invention, the frosting amount range of the air conditioning system may also be determined according to the total heat exchange area and the heat exchange capacity of the outdoor heat exchanger 2 of the air conditioning system, so as to determine whether the bypass branch 101 needs to be arranged.
The heat exchange capacity of the heat exchanger generally has a design value, the heat exchange capacity of the heat exchanger is related to factors such as outdoor environment temperature and indoor load during actual operation, the total heat exchange area of the heat exchanger is fixed and calculated, if the total heat exchange area of the fin tube type heat exchanger is the sum of the fin area and the tube area, the heat exchange capacity and the heat exchange area of the heat exchangers of different air conditioner types are different, and the optimal frosting amount range, within which the heat exchange capacity of the air conditioner type cannot be deteriorated, is determined according to the corresponding heat exchange capacity and the size of the heat exchange area of each air conditioner type, so that the heat exchange capacity is prevented from being rapidly reduced due to serious frosting, and the air conditioning system is ensured to have higher heating energy efficiency.
In the specific implementation process of the embodiment of the invention, the amount of frosting determines the amount of heat used for defrosting, the larger the overall value of the range of the frosting amount is, that is, the more the frosting amount is, the more the heat needed for defrosting is, the more the refrigerant is needed, the larger the resistance in the outdoor heat exchange tube 20 is, specifically, in the heat exchange tubes with the same pipe diameter is, the more the refrigerant is, the larger the density of the refrigerant is, and the calculation formula of the on-way resistance and the local resistance is known, the larger the on-way resistance and the local resistance at this time is, the more the loss of the refrigerant is in the flow direction of the outdoor heat exchange tube 20 along the refrigerant, the heat used for heat exchange is gradually reduced, the defrosting efficiency of each heat exchange tube section 200 is different, and at this time, a bypass branch 101 is needed to be arranged to directly guide the refrigerant in the compressor 1 to the corresponding node of the heat exchange tube for heat exchange; when the frost formation amount is small, the influence of the resistance in the pipe on the refrigerant is small, and whether the bypass branch 101 is arranged or not is mainly determined by the pipe length L.
Wherein, when the frost formation amount is small, as shown in the above formula of on-way resistance and local resistance, the longer the tube length of the outdoor heat exchange tube 20 is, the larger the resistance thereof is, and at this time, even if the frost formation amount is small, the bypass branch 101 is required to be arranged to directly introduce the drainage in the compressor 1 to the corresponding heat exchange tube section 200.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
the defrosting shunting method provided by the invention comprises the following steps: determining the heat exchange difference value delta k between the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tube 20 of the outdoor heat exchanger 2 and the chamberThe tube length L of the outer heat exchange tube 20; judging the frost formation amount or the difference of the heat exchange amount along the pipeline flowing direction of the outdoor heat exchange pipe 20 according to the heat exchange difference value delta k and the pipe length L so as to determine the number n of the bypass branches 101 communicated with the outdoor heat exchange pipe 20; one end of the bypass branch 101 is communicated with an outlet of the air conditioning system, and the other end of the bypass branch 101 is communicated with the middle part of the outdoor heat exchange tube 20; n is an integer greater than or equal to 0; the method for determining the number n of the bypass branches communicated with the outdoor heat exchange pipe comprises the following steps: when the delta k is smaller than a first preset heat exchange coefficient k 1 Then, the actual length L and the first preset length L of the outdoor heat exchange tube are judged 1 The magnitude relationship between them; when the actual pipe length L is less than or equal to the first preset pipe length L 1 When, take n =0; when the delta k is more than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 Then, the actual length L and the second preset length L of the outdoor heat exchange tube are judged 2 The magnitude relationship between them; second predetermined tube length L 2 Is less than the first preset pipe length L 1 (ii) a When the actual pipe length L is less than or equal to the second preset pipe length L 2 When n =0; otherwise, according to the actual tube length L and the first preset heat exchange coefficient k 1 Obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube, and obtaining the minimum number of bypass branches communicated with the outdoor heat exchange tube according to the actual tube length L and a second preset heat exchange coefficient k 2 Obtaining the maximum value of bypass branches communicated with the outdoor heat exchange tube, and determining the number n of the bypass branches according to delta k; when delta k is larger than a second preset heat exchange coefficient k 2 When the heat exchange pipe section is divided into a first heat exchange pipe section and a second heat exchange pipe section, and the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section is smaller than k 2 (ii) a And judging the number n of bypass branches communicated with the shunting of the first heat exchange pipe section and the second heat exchange pipe section respectively according to the maximum heat exchange coefficient difference value of the first heat exchange pipe section and the second heat exchange pipe section and the length of the pipe sections. In this way, the number of the bypass branches 101 is determined by the defrosting splitting method of the present invention to split the refrigerant of the outdoor heat exchanger 2 in the air conditioning system, so that each heat exchange tube segment 200 of the outdoor heat exchange tube 20 of the outdoor heat exchanger 2 can be defrosted synchronously, thereby solving the problem of synchronous defrosting in the prior artPoor defrosting effect and low defrosting efficiency.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A defrosting and shunting method is used for shunting a refrigerant of an outdoor heat exchanger (2) in an air conditioning system, and is characterized by comprising the following steps:
determining a heat exchange difference value delta k between the maximum heat exchange coefficient and the minimum heat exchange coefficient of an outdoor heat exchange pipe (20) of the outdoor heat exchanger (2) and the pipe length L of the outdoor heat exchange pipe (20);
judging the difference of the frost formation amount or the heat exchange amount along the pipeline flowing direction of the outdoor heat exchange pipe (20) according to the heat exchange difference value delta k and the pipe length L so as to determine the number n of bypass branches (101) communicated with the outdoor heat exchange pipe (20);
one end of the bypass branch (101) is communicated with an outlet of the compressor, and the other end of the bypass branch (101) is communicated with the middle of the outdoor heat exchange tube (20); n is an integer greater than or equal to 0;
the method for determining the number n of the bypass branches (101) communicated with the outdoor heat exchange pipe (20) comprises the following steps:
when the delta k is smaller than a first preset heat exchange coefficient k 1 Then, the actual length L and the first preset length L of the outdoor heat exchange tube (20) are judged 1 The magnitude relationship between them;
when the actual pipe length L is less than or equal to the first preset pipe length L 1 When, take n =0;
when the delta k is more than or equal to a first preset heat exchange coefficient k 1 And is less than or equal to a second preset heat exchange coefficient k 2 Then, the actual length L and the second preset length L of the outdoor heat exchange tube (20) are judged 2 The magnitude relationship between them; what is needed isThe second preset pipe length L 2 Is less than the first preset pipe length L 1 ；
When the actual pipe length L is less than or equal to a second preset pipe length L 2 When, take n =0; otherwise, according to the actual tube length L and the first preset heat exchange coefficient k 1 Obtaining the minimum number of bypass branches (101) communicated with the outdoor heat exchange tube (20), and according to the actual tube length L and the second preset heat exchange coefficient k 2 Obtaining the maximum value of bypass branches (101) communicated with the outdoor heat exchange tube (20), and determining the number n of the bypass branches (101) according to delta k;
when delta k is larger than a second preset heat exchange coefficient k 2 When the heat exchange pipe section (200) is divided into a first heat exchange pipe section (201) and a second heat exchange pipe section (202), and the maximum heat exchange coefficient difference value of the first heat exchange pipe section (201) and the second heat exchange pipe section (202) is smaller than k 2 ；
And the number n of bypass branches (101) communicated with the branches of the first heat exchange pipe section (201) and the second heat exchange pipe section (202) is judged according to the maximum heat exchange coefficient difference value and the pipe section length of the first heat exchange pipe section (201) and the second heat exchange pipe section (202).
2. The defrost diversion method of claim 1, further comprising:
and determining the heat exchange coefficient k of each position of each outdoor heat exchange tube (20) of the outdoor heat exchanger (2) according to the parameters of the outdoor heat exchanger (2) so as to determine the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange tube (20).
3. The defrost diversion method of claim 1, further comprising, after determining the heat transfer coefficient k for each location of each outdoor heat exchange tube (20):
drawing a heat exchange coefficient k-x curve of the corresponding outdoor heat exchange tube (20);
determining the maximum heat exchange coefficient and the minimum heat exchange coefficient of the outdoor heat exchange pipe (20) according to the heat exchange coefficient k-x curve;
in the heat exchange coefficient k-x curve, the origin of coordinates is a refrigerant inlet point when the air conditioning system is in heating operation, the abscissa x represents the tube length of the outdoor heat exchange tube (20), the direction of the abscissa x is the flowing direction of the refrigerant in the outdoor heat exchange tube (20), and the ordinate k represents the heat exchange coefficient k.
4. Defrost diversion method according to claim 1, characterized in that after determining the number n of bypass branches (101), the defrost diversion method further comprises:
determining the ratio of frosting amount of a plurality of heat exchange tube sections (200) of the outdoor heat exchange tube (20) which are divided by the n bypass branches (101) according to the flow resistance of the n bypass branches (101);
the position of a bypass node (210) of the outdoor heat exchange tube (20) for communicating with the bypass branch (101) is determined according to the magnitude of the heat exchange amount at each position of the outdoor heat exchange tube (20) in the refrigerant flowing direction and the ratio of the frost formation amounts of the plurality of heat exchange tube sections (200).
5. The defrost diversion method of claim 4, further comprising:
when the air conditioning system is in a heating mode, calculating the heat exchange quantity of each position of the outdoor heat exchange pipe (20) along the flowing direction of the refrigerant;
and the circulation resistance of the n bypass branches (101) is obtained according to the heat exchange quantity of each position of the outdoor heat exchange pipe (20) along the flowing direction of the refrigerant.
6. The defrost diversion method according to claim 5, wherein after deriving the magnitude of the heat exchange amount at each position of the outdoor heat exchange tube (20) in the refrigerant flow direction, said defrost diversion method further comprises:
an M-x distribution curve of the frosting amount M along the tube length direction of the outdoor heat exchange tube (20) is obtained, and the position of a bypass node (210) of the outdoor heat exchange tube (20) is determined according to the M-x distribution curve and the ratio of the frosting amounts of the plurality of heat exchange tube sections (200).
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| CN117128631A (en) * | 2022-05-19 | 2023-11-28 | 广东美的制冷设备有限公司 | Air conditioner control method and device, air conditioner and storage medium |
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| JP2003207238A (en) * | 2002-01-18 | 2003-07-25 | Fujitsu General Ltd | Defroster of air conditioner |
| KR102493237B1 (en) * | 2015-11-11 | 2023-01-30 | 엘지전자 주식회사 | Defrosting device and refrigerator having the same |
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| CN106642405A (en) * | 2016-11-02 | 2017-05-10 | 珠海格力电器股份有限公司 | Air conditioner outdoor unit, air conditioner and defrosting control method of air conditioner outdoor unit |
| CN107036349A (en) * | 2017-06-10 | 2017-08-11 | 烟台大学 | A kind of heat pump type air conditioning system based on compressor air-discharging bypass defrosting |
| CN210569372U (en) * | 2019-06-12 | 2020-05-19 | 广东Tcl智能暖通设备有限公司 | Fin heat exchanger and heat pump machine |
| CN110926051A (en) * | 2019-11-21 | 2020-03-27 | 广东美的暖通设备有限公司 | Outdoor heat exchanger assembly, air conditioning system and defrosting method thereof |
| CN111156653B (en) * | 2019-12-16 | 2021-01-29 | 珠海格力电器股份有限公司 | Fault detection method for hot defrosting electromagnetic bypass valve, storage medium and air conditioner |
| CN113124513B (en) * | 2021-05-06 | 2022-05-10 | 珠海格力电器股份有限公司 | Air conditioning system and control method thereof |
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