CN111503925A - Air conditioner and defrosting method thereof - Google Patents

Air conditioner and defrosting method thereof Download PDF

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Publication number
CN111503925A
CN111503925A CN202010363587.8A CN202010363587A CN111503925A CN 111503925 A CN111503925 A CN 111503925A CN 202010363587 A CN202010363587 A CN 202010363587A CN 111503925 A CN111503925 A CN 111503925A
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China
Prior art keywords
compressor
defrosting
air conditioner
heat exchanger
regulating valve
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CN202010363587.8A
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CN111503925B (en
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王宏宇
吕艳宗
韩冰
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CRRC Qingdao Sifang Rolling Stock Research Institute Co Ltd
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CRRC Qingdao Sifang Rolling Stock Research Institute Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B13/00—Compression machines, plants or systems, with reversible cycle
    • 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
    • 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
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F25B49/022—Compressor control arrangements

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Thermal Sciences (AREA)
  • Fuzzy Systems (AREA)
  • Mathematical Physics (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The application discloses an air conditioner and a defrosting method thereof, wherein the air conditioner comprises an indoor side heat exchanger, wherein one side of the indoor side heat exchanger is provided with an air supply temperature sensor; one side of the outdoor heat exchanger is provided with a liquid pipe temperature sensor; a compressor including a suction inlet and a discharge outlet; one end of the four-way valve is communicated with an exhaust outlet of the compressor, and the other end of the four-way valve is communicated with the indoor side heat exchanger; one end of the first regulating valve is communicated with the exhaust outlet of the compressor, and the other end of the first regulating valve is communicated with the outdoor side heat exchanger; and controlling the amount of the gas refrigerant discharged by the compressor to be conveyed to an outdoor side heat exchanger by adjusting the first adjusting valve, wherein the heat released by the part of the gas refrigerant is used for removing frost on the outdoor side heat exchanger. Therefore, the technical problem that the service life of the four-way valve and the service life of the compressor are obviously shortened due to defrosting of the air conditioner in the prior art are solved.

Description

Air conditioner and defrosting method thereof
Technical Field
The invention belongs to the technical field of air conditioners, and particularly relates to an air conditioner and a defrosting method thereof.
Background
With the rapid increase of the scale of domestic rail transit vehicles in recent years, energy conservation and emission reduction of rail transit become the key points of social attention. The rail transit vehicle air conditioner is a movable component, needs to meet special environmental requirements, is one of important factors influencing whether rail transit vehicles save energy as a key component of rail transit vehicle environmental control, and is a mainstream product in the rail transit air conditioner industry due to the fact that the rail transit vehicle air conditioner applying the frequency conversion technology and the heat pump technology is used.
One problem faced by rail transit vehicle air conditioners applying the variable frequency heat pump technology is that a method suitable for heating and defrosting in winter of rail transit vehicle air conditioners is needed to be found, and frost or ice of outdoor side heat exchangers is timely removed on the premise of not influencing normal use or causing negative influence.
However, in the prior art, during defrosting, the compressor is firstly stopped, and then the four-way valve is started to operate after the refrigerant flow direction is switched by the four-way valve; after defrosting is finished, the four-way valve switches the flow direction of the refrigerant again and shifts to normal heating operation. In the defrosting process in the prior art, the four-way valve needs to be switched twice, and the compressor needs to be started and stopped twice, so that the service lives of the four-way valve and the compressor are seriously influenced.
Disclosure of Invention
The invention aims to provide an air conditioner and a defrosting method thereof, which aim to solve the technical problem that the service life of a four-way valve and a compressor is obviously shortened due to defrosting of the air conditioner in the prior art.
In order to realize the purpose, the invention adopts the following technical scheme:
an air conditioner, comprising:
the indoor side heat exchanger is provided with an air supply temperature sensor at one side;
one side of the outdoor heat exchanger is provided with a liquid pipe temperature sensor;
a compressor including a suction inlet and a discharge outlet;
one end of the four-way valve is communicated with an exhaust outlet of the compressor, and the other end of the four-way valve is communicated with the indoor side heat exchanger;
one end of the first regulating valve is communicated with the exhaust outlet of the compressor, and the other end of the first regulating valve is communicated with the outdoor side heat exchanger; and controlling the amount of the gas refrigerant discharged by the compressor to be conveyed to an outdoor side heat exchanger by adjusting the first adjusting valve, wherein the heat released by the part of the gas refrigerant is used for removing frost on the outdoor side heat exchanger.
Preferably, the method further comprises the following steps:
the first pressure sensing switch is arranged at the exhaust outlet of the compressor and used for detecting whether the pressure at the exhaust outlet of the compressor exceeds a preset high-pressure early warning point or not;
the second pressure induction switch is arranged at the air suction inlet of the compressor and used for detecting whether the pressure at the air suction inlet of the compressor is lower than a preset low-pressure early warning point or not;
a second regulating valve between the first pressure sensor switch and the second pressure sensor switch
One end of the second regulating valve is communicated with the exhaust outlet of the compressor, and the other end of the second regulating valve is communicated with the suction inlet of the compressor.
Preferably, the method further comprises the following steps: a phase change device disposed on a shell surface of the compressor.
Preferably, the number of the outdoor heat exchangers is two, and the two outdoor heat exchangers are arranged oppositely.
A defrosting method of an air conditioner, comprising:
when the air conditioner enters a defrosting mode, the control system controls the compressor to reduce to a preset lowest frequency, then the control system controls the condensing fan to stop, and the ventilator runs at a low speed;
the control system controls the first regulating valve to be electrified and opened, controls the frequency of the compressor to be regulated to the preset operation frequency in the defrosting mode, and controls the electromagnetic valve to be electrified and operated;
at a preset defrost time t0Repeatedly judging whether the defrosting quit condition is met or not at the same time interval;
when the condition of quitting defrosting is not met, the defrosting mode continues to operate;
when the condition of quitting defrosting is reached, the air conditioner quits the defrosting mode and returns to the normal heating mode.
Preferably, the method further comprises the following steps,
at a preset defrost time t0Repeatedly judging the air supply temperature T at the same time interval2Whether or not less than preset air supply temperature T3；
If the temperature of the air supply T2Less than a predetermined supply air temperature T3When the frequency is higher than the set frequency, the control system controls the compressor to increase the running frequency; and controlling the first regulating valve to reduce the opening degree;
if the temperature of the air supply T2Greater than or equal to the preset air supply temperature T3In time, the temperature T in the liquid pipe is judged1With a preset target temperature T0The size of (2):
if the temperature T in the liquid tube1Less than a preset target temperature T0When the outdoor heat exchanger is in a closed state, the first regulating valve is controlled to increase the opening degree, and the amount of gas refrigerant flowing to the outdoor heat exchanger is increased;
if the temperature T in the liquid tube1Reach a preset target temperature T0And then judging whether the defrosting exit condition is met:
when the condition of quitting defrosting is not met, the defrosting mode continues to operate;
when the condition of quitting defrosting is reached, the air conditioner quits the defrosting mode and returns to the normal heating mode.
Preferably, the defrosting exit condition includes: determining the temperature T in the liquid tube1With a preset target temperature T0And time t for judging defrosting operation1And the minimum time t of the preset defrostingminSize; or judging the time t of defrosting operation1And the maximum time t of the preset defrostingmaxThe size of (2):
if T1≧T0And t ismin≦t1≦tmaxWhen, or t1≧tmaxWhen the air conditioner is in the defrosting mode, the air conditioner returns to the normal heating mode;
if T1﹤T0And t is1﹤tmaxWhen the outdoor heat exchanger is in a closed state, the first regulating valve is controlled to increase the opening degree, and the amount of gas refrigerant flowing to the outdoor heat exchanger is increased;
if t1﹤tminMeanwhile, the defrost mode continues to operate.
Preferably, also comprises
At a preset defrost time t0Repeatedly judging the low pressure P at the same time interval2Whether the pressure is less than a preset low-pressure early warning point P1；
If the low-pressure detection switch detects the low-pressure P2Less than or equal to low pressure early warning point P1When the control system is used, the control system controls the second regulating valve to be electrified and operated;
when the low pressure P is1≤P2≤P1When the opening degree of the second regulating valve is + delta P, the control system controls the second regulating valve to reduce the opening degree;
when the low pressure P is2≧P1And when the voltage is + delta P, the control system controls the second regulating valve to be powered off and stopped.
Preferably, the phase change device is used for heating a suction refrigerant by using heat dissipated from the shell of the compressor;
when the low-pressure detected by the low-pressure detection switch reaches an early warning point and the heat provided by the phase change device is not enough to increase the pressure or temperature of the air suction refrigerant, the control system controls the second regulating valve to open, so that a small part of exhaust gas is mixed with a large part of air suction refrigerant, the pressure or temperature of the refrigerant entering the compressor is increased, and the liquid impact of the compressor is avoided.
Compared with the prior art, the invention has the advantages and positive effects that:
1) the invention provides an air conditioner, wherein a first regulating valve is arranged in the air conditioner, one end of the first regulating valve is communicated with an exhaust outlet of a compressor, and the other end of the first regulating valve is communicated with an outdoor heat exchanger; meanwhile, one side of the indoor side heat exchanger is provided with an air supply temperature sensor; one side of the outdoor heat exchanger is provided with a liquid pipe temperature sensor. When the air conditioner enters a defrosting mode, the first regulating valve is opened under the action of the control system, and the compressor and the ventilator run at a low speed. The bypass capacity of the first regulating valve 5 is sufficient to bypass most of the compressor discharge gas into the outdoor side heat exchanger; meanwhile, the pipeline path of the first regulating valve 5 is short; when the first regulating valve is opened, most of gas refrigerant discharged from the air outlet of the compressor flows to the first regulating valve and flows to the outdoor heat exchanger through the first regulating valve, and the gas refrigerant is radiated and liquefied at the outdoor heat exchanger, so that a large amount of heat is dissipated for melting frost on the outdoor heat exchanger, and the frost on the outdoor heat exchanger is removed. Meanwhile, a small part of gas refrigerant still flows to the four-way valve and flows to the indoor side heat exchanger through the four-way valve, and heat dissipated by liquefaction of the part of gas refrigerant is used for maintaining the air supply temperature, so that the air supply temperature is still kept in a temperature range comfortable for a human body in the defrosting process of the air conditioner. By adopting the structure, when the air conditioner enters the defrosting mode, the compressor does not need to be stopped, and only the running speed of the compressor needs to be changed; meanwhile, the four-way valve does not need to be switched and can be always in a heating state, and the defrosting work of the air conditioner can be completed. Therefore, the technical problems that in the prior art, due to the fact that the four-way valve is frequently switched and the compressor is frequently started and stopped, the service life of the four-way valve and the service life of the compressor are obviously shortened due to the fact that defrosting operation of an air conditioner is conducted are solved.
2) The invention also provides a defrosting method of the air conditioner, and in the process of switching the heating mode of the air conditioner into the defrosting mode by adopting the method, the compressor only needs to adjust the running speed of the compressor without starting and stopping conversion; meanwhile, the four-way valve does not need to switch the flow direction of the gas refrigerant, and the defrosting work of the air conditioner can be completed. Therefore, the technical problems that in the prior art, due to the fact that the four-way valve is frequently switched and the compressor is frequently started and stopped, the service life of the four-way valve and the service life of the compressor are obviously shortened due to the fact that defrosting operation of an air conditioner is conducted are solved.
Drawings
FIG. 1 is a schematic view of an air conditioner according to an embodiment of the present invention;
FIG. 2 is a flow chart of a defrosting method for an air conditioner according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method for low voltage detection according to an embodiment of the present invention;
in the above figures: 1. a compressor; 2. an indoor side heat exchanger 3 and an outdoor side heat exchanger; 4. a four-way valve; 5. a first regulating valve; 6. a second regulating valve; 7. a liquid tube temperature sensor; 8. an air supply temperature sensor; 9. a phase change device; 10. a ventilator; 11. a condensing fan; 12. an electromagnetic valve; 13. a first pressure sensitive switch; 14. a second pressure sensitive switch; 15. a gas-liquid separator; 16. a throttling device; 17. a needle valve; 18. and drying the filter.
Detailed Description
The invention is described in detail below by way of exemplary embodiments. It should be understood, however, that elements, structures and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
In the description of the present invention, it should be noted that the terms "inside", "outside", "upper", "lower", "front", "rear", "first", "second", etc. indicate orientations or positional relationships based on the positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In the description of the present application, the terms "mounted," "connected," "fixed," and the like are used in a broad sense, and for example, "connected" may be a fixed connection, a detachable connection, or an integral connection; either directly or through an intermediary profile. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
The technical scheme in the embodiment of the application leads to the cross valve 4 to frequently switch for solving among the prior art because the defrosting work of air conditioner, and compressor 1 frequently opens and stops, and makes the technical problem that the life of cross valve 4 and compressor 1 obviously shortens. The general idea is as follows:
the invention provides an air conditioner, wherein a first regulating valve 5 is arranged in the air conditioner, one end of the first regulating valve is communicated with an exhaust outlet of a compressor 1, and the other end of the first regulating valve is communicated with an outdoor side heat exchanger 3; meanwhile, one side of the indoor side heat exchanger 2 is provided with an air supply temperature sensor 8; a liquid pipe temperature sensor 7 is provided at one side of the outdoor side heat exchanger 3. When the air conditioner enters the defrosting mode, the first regulating valve 5 is opened under the action of the control system, and the compressor 1 and the ventilator 10 run at a low speed. The bypass capacity of the first regulating valve 5 is sufficient to bypass most of the compressor discharge gas into the outdoor side heat exchanger; meanwhile, the pipeline path of the first regulating valve 5 is short; so that the gas refrigerant has small resistance when passing through the pipeline path and sufficient bypass flow or capacity. Therefore, when the first regulating valve 5 is opened, most of the gas refrigerant discharged from the discharge port of the compressor 1 flows to the first regulating valve 5 and flows to the outdoor heat exchanger 3 through the first regulating valve 5, and the gas refrigerant is liquefied by heat dissipation at the outdoor heat exchanger 3, so that a large amount of heat is dissipated to melt frost on the outdoor heat exchanger 3, and the frost on the outdoor heat exchanger 3 is removed. Meanwhile, a small part of gas refrigerant still flows to the four-way valve 4 and flows to the indoor side heat exchanger 2 through the four-way valve 4, and heat dissipated by liquefaction of the part of gas refrigerant is used for maintaining the air supply temperature, so that the air supply temperature is still kept in a comfortable temperature range of a human body in the defrosting process of the air conditioner. By adopting the structure, when the air conditioner enters the defrosting mode, the compressor 1 does not need to be stopped, and only the running speed of the compressor needs to be changed; meanwhile, the four-way valve 4 is not required to be switched and can be always in a heating state, and the defrosting operation of the air conditioner can be completed. Therefore, the technical problems that in the prior art, due to the fact that the four-way valve 4 is frequently switched and the compressor 1 is frequently started and stopped, the service lives of the four-way valve 4 and the compressor 1 are obviously shortened due to the fact that defrosting operation of an air conditioner is conducted are solved.
In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.
As shown in fig. 1, an air conditioner includes a refrigeration system including a compressor 1, an indoor side heat exchanger 2, an outdoor side heat exchanger 3, a four-way valve 4, and a first regulation valve 5.
An air supply temperature sensor 8 is arranged on one side of the indoor side heat exchanger 2; a liquid pipe temperature sensor 7 is provided at one side of the outdoor side heat exchanger 3. The compressor 1 comprises a suction inlet and a discharge outlet; one end of the four-way valve 4 is communicated with the exhaust outlet of the compressor 1, and the other end thereof is communicated with the indoor side heat exchanger 2. A first regulating valve 5, one end of which is communicated with the exhaust outlet of the compressor 1 and the other end of which is communicated with the outdoor side heat exchanger 3; the gas refrigerant discharged by the compressor 1 is controlled to be conveyed to the outdoor heat exchanger 3 by adjusting the first adjusting valve 5, and the heat released by the part of the gas refrigerant is used for removing frost on the outdoor heat exchanger 3.
Specifically, the compressor 1 functions to compress a driving gas refrigerant in the air-conditioning refrigerant circuit. The compressor 1 extracts the gas refrigerant from the low-pressure area, compresses the gas refrigerant, and sends the compressed gas refrigerant to the high-pressure area for cooling and condensation, namely, the gas refrigerant is sent to the condenser to change the gas refrigerant from a gas state to a liquid state, and the pressure is increased.
In this embodiment, since the first regulating valve 5 is disposed between the compressor 1 and the outdoor heat exchanger 3, that is, one end of the first regulating valve 5 is communicated with the exhaust outlet of the compressor 1, and the other end thereof is communicated with the outdoor heat exchanger 3, in this embodiment, the two outdoor heat exchangers 3 are disposed oppositely. When the air conditioner enters the defrosting mode, the first regulating valve 5 is powered on under the action of the control system, namely, the first regulating valve 5 is opened. The first regulating valve 5 is preferably a large-diameter valve, the specific model is selected according to the rated heating working condition, the manufacturer selection information and the like, and the bypass capacity of the first regulating valve 5 is enough to bypass most of the compressor exhaust gas to the outdoor heat exchanger. The line path of the first control valve 5 is also short. In summary, by comprehensively selecting the first regulating valve 5, the resistance of the gas refrigerant is small when the gas refrigerant passes through the path of the pipeline, and the bypass flow or capacity is sufficient, so that most of the compressed gas refrigerant discharged by the compressor 1 flows to the first regulating valve 5 and flows to the outdoor heat exchanger 3 through the first regulating valve 5, at this time, the outdoor heat exchanger 3 is equivalent to a condenser, the gas refrigerant is liquefied under the action of the outdoor heat exchanger, and releases a large amount of heat, and the part of heat is used for melting frost at the outdoor heat exchanger, namely, the defrosting operation of the air conditioner is completed.
Meanwhile, one end of the four-way valve 4 is communicated with an exhaust outlet of the compressor 1, and the other end thereof is communicated with one end of the indoor-side heat exchanger 2. When the air conditioner is switched to a defrosting mode, due to the arrangement of the first regulating valve 5, the four-way valve 4 enables most of gas refrigerants to flow to the heat exchanger on the outdoor side without switching the flow direction of the gas refrigerants, meanwhile, a small part of gas refrigerants flow to the heat exchanger 2 on the indoor side through the four-way valve 4, and heat generated by the part of gas refrigerants is used for maintaining the air supply temperature, so that the air supply temperature can still be kept in a comfortable temperature range of a human body even in the defrosting process by adopting the structure.
Meanwhile, a first pressure sensing switch 13 and a second pressure sensing switch 14 are further disposed at both ends of the compressor 1. The first pressure sensing switch 13 is arranged at the exhaust outlet of the compressor 1 and used for detecting whether the pressure at the exhaust outlet of the compressor 1 exceeds a preset high-pressure early warning point or not; when the pressure of the gas refrigerant discharged from the compressor 1 exceeds the preset highest pressure point, the gas refrigerant is fed back to the control system through the first pressure sensing switch 13, and the control system controls the compressor 1 to perform corresponding actions, so that the pressure of the gas refrigerant is adjusted to be within a reasonable range. Further, a second pressure sensing switch 14 is disposed at the air suction inlet of the compressor 1 for detecting whether the pressure at the air suction inlet of the compressor 1 is lower than a preset low-pressure early warning point P1。
Further, in order to avoid the liquid impact phenomenon of the compressor 1, a second regulating valve 6 which is a small bypass valve is also arranged in the embodiment. Which is located between a first pressure-sensitive switch 13 and a second pressure-sensitive switch 14, one end of the second regulating valve 6 is communicated with the exhaust outlet of the compressor 1, and the other end is communicated with the suction inlet of the compressor 1. When the second pressure-sensitive switch 14 detects that the pressure at the air suction inlet is lower than the preset low-pressure early warning point P1When the compressor is running, the control system controls the second regulating valve 6 to open, so that a small part of gas refrigerant discharged by the compressor 1 flows back to the compressor 1 and is communicated with a large part of gas refrigerantThe gas refrigerant sucked at the suction inlet is mixed, so that the pressure or the temperature of the gas refrigerant entering the compressor 1 is increased, and the liquid impact of the compressor 1 is avoided.
In order to further avoid the liquid impact phenomenon of the compressor 1, a phase change device 9 is further arranged in the example, specifically, the phase change device 9 is a device for absorbing and storing heat of a shell of the compressor 1, and mainly comprises a phase change material, a building envelope, a winding coil (generally a copper pipe), a device inlet and a device outlet, and the like. Specifically, the phase change material may be a solid-solid composite phase change material, which includes paraffin and alumina and/or graphite, wherein the paraffin is a base material, and the alumina and/or graphite is an additive. The phase change energy storage material keeps higher latent heat of phase change, specific heat capacity and density and has higher heat conductivity coefficient by adding the additive, overcomes the defect of low heat conductivity coefficient of the traditional phase change energy storage material which only uses paraffin, belongs to solid-solid phase change, does not have the problem of flowing leakage, has no expansion rate in the phase change process, and has lower requirements on the stress and the strength of a carrier. By adopting the phase change device 9, the heat dissipated by the shell of the compressor 1 can be used for heating sucked gas refrigerant, and the phenomenon that the refrigerant gas with overcooled outlet of the outdoor heat exchanger 3 enters the compressor 1 to possibly cause liquid impact on the compressor 1 during defrosting is avoided. The phase change device 9 utilizes the heat generated by the compressor 1, does not use other electric energy or energy, and saves more energy. During heating operation, the phase change device 9 provides heat insulation for the compressor 1, which is beneficial to improving the exhaust temperature and the oil return effect and improving the reliability of the compressor 1.
Meanwhile, the air conditioner further includes a gas-liquid separator 15, a throttling device 16, a needle valve 17, a drying filter 18, etc., and the structure and the function thereof are known to those skilled in the art, and thus, detailed description thereof is omitted.
By adopting the structure, when the air conditioner enters the defrosting mode, the compressor 1 does not need to be stopped, and only the running speed of the compressor needs to be changed; meanwhile, the four-way valve 4 does not need to be switched and can be always in a heating mode to complete the defrosting work of the air conditioner. Therefore, the technical problems that in the prior art, due to the fact that the four-way valve 4 is frequently switched and the compressor 1 is frequently started and stopped, the service lives of the four-way valve 4 and the compressor 1 are obviously shortened due to the fact that defrosting operation of an air conditioner is conducted are solved. Meanwhile, through adopting the above structure, in the defrosting process of the air conditioner, because the four-way valve 4 does not switch the flow direction of the gas refrigerant, a small part of the gas refrigerant still flows to the four-way valve 4 and flows to the indoor side heat exchanger 2 through the four-way valve 4, and the heat dissipated by liquefaction of the part of the gas refrigerant is used for maintaining the air supply temperature, so that in the defrosting process of the air conditioner, the air supply temperature still keeps in a comfortable temperature range of a human body, and the problem that the air conditioner is poor in cold air blowing easily when defrosting in the prior art is solved.
As shown in fig. 2, an embodiment of the present invention further provides a defrosting method of an air conditioner, including:
when the air conditioner enters a defrosting mode, the control system controls the compressor 1 to be reduced to a preset minimum frequency, then the control system controls the condensing fan 11 to stop, and the ventilator 10 runs at a low speed.
In this embodiment, the preset lowest frequency of the compressor 1 is preferably 30Hz, and the condensing fan 11 is generally a constant speed fan, and a multi-gear or variable frequency fan can be selected according to actual needs. The ventilator 10 is generally a multi-stage or variable frequency ventilator, and when entering the defrosting mode, the ventilator 10 is preferably adjusted to operate in the second stage, that is, the ventilation volume is reduced, and the heat dissipation volume of the indoor-side heat exchanger 2 per unit time is reduced.
The control system controls the first regulating valve 5 to be electrified and opened, and controls the frequency of the compressor 1 to be regulated to the preset running frequency in the defrosting mode. In the present embodiment, the preset operating frequency of the compressor 1 is preferably 60 Hz; meanwhile, the solenoid valve 12 is powered on to start defrosting.
After defrosting operation is carried out for a period of time, the control system starts to judge whether the air conditioner reaches the condition of quitting defrosting at the moment. In other words, the control system determines whether the condition for exiting the defrost is reached every 30S or 60S within the preset defrost time. If the condition of quitting defrosting is met, the air conditioner finishes defrosting and restores to a normal heating state, and if the condition of quitting defrosting is not met, the defrosting operation continues.
Specifically, theThe conditions for exiting defrost include: determining the temperature T in the liquid tube1With a preset target temperature T0While also judging the time t of defrosting operation1And the minimum time t of the preset defrostingminPresetting the maximum defrosting time tmaxThe size of (2):
if T1≧T0And t ismin≦t1≦tmaxWhen, or, t1≧tmaxAnd when the air conditioner is in the defrosting mode, the air conditioner returns to the normal heating mode. In other words, the condition for satisfying the exit defrosting in the present embodiment has two cases. First, if the actual defrosting time is within the preset minimum defrosting time tminAnd maximum time tmaxAnd after the temperature in the liquid pipe reaches a preset target value, at a preset time t2Internal, system to temperature T1、T0The temperature of the air conditioner is continuously judged, the temperature is kept stable within a certain time, and after the temperature is kept stable, the condition of quitting defrosting is met. Secondly, as long as the defrosting time reaches the maximum time t of the preset defrostingmaxAnd then, the condition of quitting defrosting is met. Specifically, when the defrost exit condition is reached, the control system controls the compressor 1 to decrease to the lowest frequency, i.e., to 30 Hz; the first regulating valve 5 is powered off to stop running, and the electromagnetic valve 12 is powered off to stop running; at this time, the condensing fan 11 is started and operated, and the ventilator 10 is restored to the normal operation speed; then, the compressor 1 is also restored to the normal operation frequency of the heating mode, at which time the air conditioner is restored to the normal heating mode.
If T1﹤T0And t is1﹤tmaxAnd controlling the first regulating valve 5 to increase the opening degree and increase the amount of the gas refrigerant flowing to the outdoor heat exchanger 3. That is, the condition that the defrosting is not finished is indicated at this moment, the control system controls the first regulating valve 5 to increase the opening degree, so that more gas refrigerants flow to the outdoor heat exchanger 3, namely, more refrigerating gases release more heat in the liquefying process, the defrosting strength is further increased, and the defrosting process is accelerated;
if t1﹤tminIn time, because the defrosting time is not upAnd the defrosting mode continues to operate when the preset defrosting minimum time is reached.
Because the continuous input of fresh air is ensured in the rail transit vehicle, even if the air conditioner is in the defrosting process, the ventilator 10 of the air conditioner is in a running state, so that the air supply temperature in the defrosting process cannot be ensured to be within a proper air supply temperature range, and the air supply temperature is possibly lower than 19 ℃, thereby causing discomfort of blowing cold air to people. If the proper temperature is to be kept, the electric heater needs to be started to improve the air supply temperature, but the power consumption of the air conditioner is increased, the energy is wasted, and the requirements of energy conservation and emission reduction are not met. In order to solve this problem, in the present embodiment, the amount of the gas refrigerant flowing to the indoor side heat exchanger 2 is controlled by adjusting the size of the first adjustment valve 5. Specifically, when the preset defrosting time is reached, whether the air supply temperature is lower than the preset air supply temperature is judged.
After defrosting operation is carried out for a period of time, the control system starts to judge whether the air supply temperature reaches the preset air supply temperature. In other words, the control system in this embodiment determines whether the supply air temperature reaches the preset supply air temperature every 30S or 60S intervals during the preset defrosting time.
At a preset defrost time t0The air supply temperature T is circularly judged at the same time interval2Whether or not less than preset air supply temperature T3：
If the temperature of the air supply T2Less than a predetermined supply air temperature T3When the frequency is higher than the set frequency, the control system controls the compressor to increase the running frequency; and controlling the first regulating valve to reduce the opening degree; more gas refrigerant flows to the indoor side heat exchanger 2 through the four-way valve 4, so that the air supply temperature is increased.
If the temperature of the air supply T2Greater than or equal to the preset air supply temperature T3In time, the temperature T in the liquid pipe is judged1With a preset target temperature T0The size of (2):
if the temperature T in the liquid tube1Less than a preset target temperature T0When the outdoor heat exchanger is in a closed state, the first regulating valve is controlled to increase the opening degree, and the amount of gas refrigerant flowing to the outdoor heat exchanger is increased;
if the temperature T in the liquid tube1Reach a preset target temperature T0And then judging whether the defrosting exit condition is met:
when the condition of quitting defrosting is not met, the defrosting mode continues to operate;
when the condition of quitting defrosting is reached, the air conditioner quits the defrosting mode and returns to the normal heating mode.
Specifically, the defrosting exit condition includes: determining the temperature T in the liquid tube1With a preset target temperature T0While also judging the time t of defrosting operation1And the minimum time t of the preset defrostingminPresetting the maximum defrosting time tmaxThe size of (2):
if T1﹤T0And t is1﹤tmaxAnd controlling the first regulating valve 5 to increase the opening degree and increase the amount of the gas refrigerant flowing to the outdoor heat exchanger 5. That is, the condition that the defrosting is not finished is indicated at this moment, the control system controls the first regulating valve 5 to increase the opening degree, so that more gas refrigerants flow to the outdoor heat exchanger 3, namely, more refrigerating gases release more heat in the liquefying process, the defrosting strength is further increased, and the defrosting process is accelerated;
if t1﹤tminIn time, the defrosting mode continues to operate because the defrosting time does not reach the preset minimum defrosting time;
if T1≧T0And t ismin≦t1≦tmaxWhen, or, t1≧tmaxAnd when the air conditioner is in the defrosting mode, the air conditioner returns to the normal heating mode. In other words, the condition for satisfying the exit defrosting in the present embodiment has two cases. First, if the actual defrosting time is between the preset minimum defrosting time and the preset maximum defrosting time, and the temperature in the liquid pipe reaches the preset target value, the condition of exiting defrosting is satisfied. Secondly, as long as the defrosting time reaches the maximum time of the preset defrosting, the condition of quitting the defrosting is met. Specifically, when the defrost exit condition is reached, the control system controls the compressor 1 to decrease to the lowest frequency, i.e., to 30 Hz; the first regulating valve 5 is powered off and stops running at the same timeThe electromagnetic valve 12 is powered off and stops; at this time, the condensing fan 11 is started and operated, and the ventilator 10 is restored to the normal operation speed; then, the compressor 1 is also restored to the normal operation frequency of the heating mode, at which time the air conditioner is restored to the normal heating mode.
Further, as shown in fig. 3, in order to avoid the liquid impact phenomenon of the compressor 1, after the defrosting operation is performed for a period of time, the control system starts to determine whether the low pressure is lower than a preset low pressure early warning point P at this time1In this embodiment, P1The low pressure is 0.2MPa, in other words, the control system determines the low pressure every 30S or 60S intervals in the present embodiment during the preset defrosting time. If the low-pressure detection switch detects the low-pressure P2Less than or equal to low pressure early warning point P1When the control system is used, the control system controls the second regulating valve 6 to be electrified and operated; when the low pressure P is1≤P2≤P1When + Δ P is equal to 0.1MPa, the control system controls the second regulating valve 6 to decrease the opening degree so as to further increase the low-pressure, that is, further increase the pressure or temperature of the gas refrigerant in the compressor 1. When the low pressure P is2≧P1At + Δ P, the control system controls the second regulating valve 6 to be de-energized and stopped, i.e. the low pressure has satisfied the preset condition.
Meanwhile, in order to further avoid the liquid impact phenomenon of the compressor 1, in the defrosting method of the embodiment, the phase change device 9 is also used for absorbing and storing heat dissipated by the shell of the compressor 1 and using the heat for heating sucked gas refrigerant, so that the phenomenon that the liquid impact of the compressor 1 is possibly caused when refrigerant gas with super-cooled outlet of the outdoor heat exchanger 3 enters the compressor 1 during defrosting is avoided. In the method, the phase change device 9 utilizes the heat generated by the compressor 1, and does not use other electric energy or energy, thereby saving more energy. During heating operation, the phase change device 9 provides heat insulation for the compressor 1, which is beneficial to improving the exhaust temperature and the oil return effect and improving the reliability of the compressor 1.
In conclusion, by adopting the method, the compressor 1 only needs to adjust the running speed of the air conditioner in the process of switching the heating mode of the air conditioner into the defrosting mode without starting and stopping conversion; meanwhile, the four-way valve 4 can complete the defrosting operation of the air conditioner without switching the flow direction of the gas refrigerant. Therefore, the technical problems that in the prior art, due to the fact that the four-way valve 4 is frequently switched and the compressor 1 is frequently started and stopped, the service lives of the four-way valve 4 and the compressor 1 are obviously shortened due to the fact that defrosting operation of an air conditioner is conducted are solved.
In order to more clearly explain the present application, the working principle of the present invention is further explained by taking the following embodiments as examples:
one heat pump air conditioning unit operates in a heating mode using R407C refrigerant (refrigerant).
When the defrosting entering condition is met, the compressor 1 is firstly reduced to the lowest frequency of 30Hz, the condensing fan 11 (a constant speed fan) is stopped, the ventilator 10 is adjusted to 2-gear low-gear operation, the first adjusting valve 5 is electrified to operate, the compressor 1 operates according to the defrosting preset operating frequency of 60Hz, and the electromagnetic valve 12 is electrified to operate; meanwhile, the heat of the shell of the compressor 1 absorbed by the phase change device 9 is used for heating sucked gas refrigerant, wherein the phase change device 9 is preferably a solid-solid composite phase change energy storage material with the phase change temperature of 30 ℃, and whether the low-pressure early warning point P is reached or not is judged after 60s1And whether the air supply temperature is lower than the preset air supply temperature.
If the pressure is lower than the low-pressure early warning point P1The second control valve 6 is electrically operated at 0.2MPa (gauge pressure). When the low pressure P is1≤P2≤P1After + Δ P, the second regulating valve 6 decreases the valve opening, and decreases the bypass amount. When the low pressure P is2≧P1At + Δ P, the control system controls the second regulating valve 6 to be de-energized and stopped, i.e. the low pressure has satisfied the preset condition.
Meanwhile, whether the air supply temperature is less than 19 ℃ of the preset air supply temperature or not is judged, if the air supply temperature is less than 19 ℃, the operation frequency of the compressor 1 is increased but cannot be higher than the highest operation frequency of the compressor 1, and the opening degree of the first regulating valve 5 is reduced, so that more gas refrigerants flow to the indoor side heat exchanger 2 through the four-way valve 4, and the air supply temperature is increased. If the temperature is higher than or equal to the preset air supply temperature of 19 ℃, then the air enters a liquid pipe to judge whether the temperature is lower than the defrosting exit target temperature value by 10 ℃, if the temperature is lower than 10 ℃, the running frequency of the compressor 1 is increased, the opening degree of a first adjusting valve is increased, and more gas refrigerants flow to the outdoor heat exchanger 3 to be defrosted;
if the temperature of the liquid pipe reaches the preset defrosting exit target temperature, after the defrosting exit condition is reached, the compressor 1 is firstly reduced to the lowest frequency of 30Hz, the first regulating valve 5 and the electromagnetic valve 12 are powered off and stopped, the condensing fan 11 is started to operate, the ventilator 10 is recovered to normally operate, the compressor 1 is recovered to normally operate, the air conditioning unit enters a normal heating mode, and the defrosting operation of the air conditioner is finished.

Claims (9)

1. An air conditioner, comprising:
the indoor side heat exchanger is provided with an air supply temperature sensor at one side;
one side of the outdoor heat exchanger is provided with a liquid pipe temperature sensor;
a compressor including a suction inlet and a discharge outlet;
one end of the four-way valve is communicated with an exhaust outlet of the compressor, and the other end of the four-way valve is communicated with the indoor side heat exchanger;
one end of the first regulating valve is communicated with the exhaust outlet of the compressor, and the other end of the first regulating valve is communicated with the outdoor side heat exchanger; and controlling the amount of the gas refrigerant discharged by the compressor to be conveyed to an outdoor side heat exchanger by adjusting the first adjusting valve, wherein the heat released by the part of the gas refrigerant is used for removing frost on the outdoor side heat exchanger.
2. The air conditioner according to claim 1, further comprising:
the first pressure sensing switch is arranged at the exhaust outlet of the compressor and used for detecting whether the pressure at the exhaust outlet of the compressor exceeds a preset high-pressure early warning point or not;
the second pressure induction switch is arranged at the air suction inlet of the compressor and used for detecting whether the pressure at the air suction inlet of the compressor is lower than a preset low-pressure early warning point or not;
and the second regulating valve is positioned between the first pressure sensor switch and the second pressure sensor switch, one end of the second regulating valve is communicated with the exhaust outlet of the compressor, and the other end of the second regulating valve is communicated with the suction inlet of the compressor.
3. The air conditioner according to claim 1, further comprising: a phase change device disposed on a shell surface of the compressor.
4. The air conditioner according to any one of claims 1 to 3, wherein there are two outdoor side heat exchangers, and the two outdoor side heat exchangers are disposed to be opposed to each other.
5. A defrosting method of an air conditioner, comprising:
when the air conditioner enters a defrosting mode, the control system controls the compressor to reduce to a preset lowest frequency, then the control system controls the condensing fan to stop, and the ventilator runs at a low speed;
the control system controls the first regulating valve to be electrified and opened, controls the frequency of the compressor to be regulated to the preset operation frequency in the defrosting mode, and controls the electromagnetic valve to be electrified and operated;
at a preset defrost time t0Repeatedly judging whether the defrosting quit condition is met or not at the same time interval;
when the condition of quitting defrosting is not met, the defrosting mode continues to operate;
when the condition of quitting defrosting is reached, the air conditioner quits the defrosting mode and returns to the normal heating mode.
6. The defrosting method of an air conditioner according to claim 5, further comprising,
at a preset defrost time t0Repeatedly judging the air supply temperature T at the same time interval2Whether or not less than preset air supply temperature T3；
If the temperature of the air supply T2Less than a predetermined supply air temperature T3When the frequency is higher than the set frequency, the control system controls the compressor to increase the running frequency; and controlling the first regulating valve to reduce the opening degree;
if the temperature of the air supply T2Greater than or equal to the preset air supply temperature T3In time, the temperature T in the liquid pipe is judged1With a preset target temperature T0The size of (2):
if the temperature T in the liquid tube1Less than a preset target temperature T0When the outdoor heat exchanger is in a closed state, the first regulating valve is controlled to increase the opening degree, and the amount of gas refrigerant flowing to the outdoor heat exchanger is increased;
if the temperature T in the liquid tube1Reach a preset target temperature T0And then judging whether the defrosting exit condition is met:
when the condition of quitting defrosting is not met, the defrosting mode continues to operate;
when the condition of quitting defrosting is reached, the air conditioner quits the defrosting mode and returns to the normal heating mode.
7. A defrosting method of an air conditioner according to claim 5 or 6, wherein the condition of exiting defrosting includes: determining the temperature T in the liquid tube1With a preset target temperature T0And time t for judging defrosting operation1And the minimum time t of the preset defrostingminSize; or judging the time t of defrosting operation1And the maximum time t of the preset defrostingmaxThe size of (2):
if T1≧T0And t ismin≦t1≦tmaxWhen, or t1≧tmaxWhen the air conditioner is in the defrosting mode, the air conditioner returns to the normal heating mode;
if T1﹤T0And t is1﹤tmaxWhen the outdoor heat exchanger is in a closed state, the first regulating valve is controlled to increase the opening degree, and the amount of gas refrigerant flowing to the outdoor heat exchanger is increased;
if t1﹤tminMeanwhile, the defrost mode continues to operate.
8. The defrosting method of an air conditioner according to claim 7, further comprising
At a preset defrost time t0Repeatedly judging the low pressure P at the same time interval2Whether or not toLess than preset low pressure early warning point P1；
If the low-pressure detection switch detects the low-pressure P2Less than or equal to low pressure early warning point P1When the control system is used, the control system controls the second regulating valve to be electrified and operated;
when the low pressure P is1≤P2≤P1When the opening degree of the second regulating valve is + delta P, the control system controls the second regulating valve to reduce the opening degree;
when the low-pressure P2 is not less than P1+ delta P, the control system controls the second regulating valve to be powered off and stopped.
9. The defrosting method for an air conditioner according to claim 7, further comprising using the heat dissipated from the casing of the compressor by the phase change device to heat a suction refrigerant;
when the low-pressure detected by the low-pressure detection switch reaches an early warning point and the heat provided by the phase change device is not enough to increase the pressure or temperature of the air suction refrigerant, the control system controls the second regulating valve to open, so that a small part of exhaust gas is mixed with a large part of air suction refrigerant, the pressure or temperature of the refrigerant entering the compressor is increased, and the liquid impact of the compressor is avoided.
CN202010363587.8A 2020-04-30 2020-04-30 Air conditioner and defrosting method thereof Active CN111503925B (en)

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