CN113776219B - Air source heat pump, air conditioner and control method suitable for severe cold area - Google Patents

Air source heat pump, air conditioner and control method suitable for severe cold area Download PDF

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Publication number
CN113776219B
CN113776219B CN202110963403.6A CN202110963403A CN113776219B CN 113776219 B CN113776219 B CN 113776219B CN 202110963403 A CN202110963403 A CN 202110963403A CN 113776219 B CN113776219 B CN 113776219B
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valve
state
interface
compressor
switched
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CN113776219A (en
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王宝龙
王文涛
于天蝉
祝子涵
杨帆
范佳乐
于佳丘
石文星
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Tsinghua University
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Tsinghua University
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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
    • 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
    • F25B31/00—Compressor arrangements
    • 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
    • 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
    • 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
    • F25B5/00—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity
    • 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
    • F25B6/00—Compression machines, plants or systems, with several condenser circuits

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

Abstract

The invention provides an air source heat pump, an air conditioner and a control method suitable for severe cold areas, wherein the air source heat pump suitable for severe cold areas comprises a main circulation loop and an air supplementing branch, and the main circulation loop comprises a compression assembly, a four-way valve, a first heat exchanger, a first expansion valve, a flash evaporator, a second expansion valve and a second heat exchanger. The four-way valve is arranged between the compression assembly and the first heat exchanger and the second heat exchanger, and the state of the four-way valve is switched to realize the switching of the refrigeration mode and the heating mode; the three-way valve is arranged between the first compressor, the second compressor and the four-way valve of the compression assembly, the states of the three-way valve and the first valve are switched, and switching between single-stage compression and double-stage compression modes is achieved. Therefore, the problem that the compressor is idle when a double-stage compression system with a refrigeration mode and a heating mode in the prior art cannot be switched between a double-stage compression working condition and a single-stage compression working condition or switched to the single-stage compression working condition is solved.

Description

Air source heat pump, air conditioner and control method suitable for severe cold area
Technical Field
The invention relates to the technical field of air conditioners, in particular to an air source heat pump suitable for severe cold regions, an air conditioner and a control method.
Background
The heat pump is a high-efficiency energy-saving heating device, the low-level heat source of the heat pump can be ambient air, and the heat pump has the characteristic of no pollutant emission. But the conventional heat pump and the current low-loop-temperature air source heat pump cannot safely and reliably operate at ultralow temperature. In order to realize the efficient operation of a heat pump system under a low-temperature working condition, a double-stage compression system formed by double cylinders or three cylinders is adopted at present so as to improve the refrigerating and heating capacities and improve the operation energy efficiency ratio when the indoor and outdoor temperature difference is large.
The two-stage compression system in the prior art generally only has a two-stage compression function, and although the two-stage compression system can operate efficiently when the indoor and outdoor temperature difference is large, the two-stage compression system still only can adopt two-stage compression circulation when the indoor and outdoor temperature difference is small. At this time, the compression ratio of each stage is too small, which results in too low efficiency of each compressor and too low energy efficiency ratio of the two-stage compression system, resulting in waste of energy. In addition, although the individual double-stage compression system with the air supply function has two operation conditions of single-stage compression and double-stage compression, the individual double-stage compression system only has a heating mode and does not have a refrigerating mode, and only one compressor is in a working state and the other compressor is in an idle state under the single-stage compression condition, so that the waste of equipment capacity is caused.
Therefore, how to solve the problem that the compressor is idle when the two-stage compression system having the refrigeration mode and the heating mode cannot be switched between the two-stage compression working condition and the single-stage compression working condition or switched to the single-stage compression working condition in the prior art becomes an important technical problem to be solved by the technical personnel in the field.
Disclosure of Invention
Aiming at the problems in the prior art, the embodiment of the invention provides an air source heat pump, an air conditioner and a control method which are suitable for severe cold areas.
The invention provides an air source heat pump suitable for severe cold areas, which comprises a main circulation loop and an air supply branch, wherein:
the main circulation loop comprises a compression assembly, a four-way valve, a first heat exchanger, a first expansion valve, a flash evaporator, a second expansion valve and a second heat exchanger which are sequentially connected;
the four-way valve is provided with a D interface connected with the exhaust end of the compression assembly, an E interface connected with the second heat exchanger, a C interface connected with the first heat exchanger and an S interface connected with the suction end of the compression assembly, and can be switched between a first state and a second state, wherein the D interface is communicated with the C interface and the E interface is communicated with the S interface in the first state, and the D interface is communicated with the E interface and the S interface is communicated with the C interface in the second state;
the compression assembly comprises a first compressor, a second compressor, a three-way valve and a first valve, wherein the air suction end of the first compressor and the air suction end of the second compressor are connected with an S interface, the air discharge end of the first compressor and the air discharge end of the second compressor are connected with a D interface, the three-way valve is provided with an L interface connected with the air discharge end of the first compressor, an M interface connected with the D interface and an N interface connected with the air suction end of the second compressor, the first valve is arranged between the air suction end of the second compressor and the S interface, when the first valve is in a conducting state, a circulating medium flowing out of the S interface can simultaneously enter the air suction end of the first compressor and the air suction end of the second compressor, and when the first valve is in a stopping state, the first valve limits that the circulating medium flowing out of the S interface can only directly enter the air suction end of the first compressor A terminal;
the three-way valve can be switched between a third state and a fourth state, wherein in the third state, the L interface is communicated with the M interface, the N interface is in a cut-off state, in the fourth state, the L interface is communicated with the N interface, and the M interface is in a cut-off state;
the flash evaporator is provided with an X interface, a Y interface and a Z interface, the first expansion valve and the second expansion valve are respectively connected with the X interface and the Y interface, the first expansion valve and the second expansion valve can realize forward throttling, reverse throttling, full-open conduction and non-conduction closing functions, one end of the air supply branch is connected with the Z interface of the flash evaporator, the other end of the air supply branch is connected with the air suction end of the second compressor, and the second valve is arranged on the air supply branch.
According to the air source heat pump suitable for the severe cold region, the first compressor and the second compressor are mutually independent compressors, or the first compressor and the second compressor are integrated into a whole, namely a double-suction double-row compressor.
According to the air source heat pump suitable for the severe cold area, the first heat exchanger is provided with a plurality of heat exchangers, and the second heat exchanger is provided with a plurality of heat exchangers.
According to the air source heat pump suitable for the severe cold area, the first heat exchanger comprises a first heat exchange channel for air or water to circulate and a second heat exchange channel for circulating a circulating medium to circulate, and two ends of the second heat exchange channel are respectively connected with the C interface and the first expansion valve;
the second heat exchanger comprises a third heat exchange channel for air circulation and a fourth heat exchange channel for circulation of a circulating medium, and two ends of the fourth heat exchange channel are connected with the E port and the second expansion valve respectively.
According to the air source heat pump suitable for the severe cold area provided by the invention, the air source heat pump further comprises:
the first fan or the water pump is used for driving air or water to circulate in the first heat exchange channel;
and the second fan is used for driving air to circulate in the third heat exchange channel.
The invention also provides an air conditioner which comprises the air source heat pump suitable for the severe cold area.
According to the air conditioner provided by the invention, the air conditioner comprises a first shell and a second shell, wherein a first heat exchanger is arranged in the first shell to form an indoor unit, a first compressor, a second compressor, a three-way valve, a first valve, a four-way valve, a first expansion valve, a flash evaporator, a second expansion valve, a second heat exchanger and a second valve are arranged in the second shell to form an outdoor unit, and the indoor unit is connected with the outdoor unit.
According to the air conditioner provided by the invention, the air conditioner comprises a first shell and a second shell, wherein a first expansion valve and a first heat exchanger are arranged in the first shell to form an indoor unit, a first compressor, a second compressor, a three-way valve, a first valve, a four-way valve, a flash evaporator, a second expansion valve, a second heat exchanger and a second valve are arranged in the second shell to form an outdoor unit,
the indoor unit is provided with at least one, the outdoor unit is provided with one, and the indoor unit is connected with the outdoor unit.
The invention also provides a control method of the air source heat pump, which can control the air source heat pump suitable for the severe cold area to operate in a single-stage compression heating mode, a double-stage compression heating mode and a single-stage compression refrigeration mode respectively, and the control method comprises the following steps:
controlling the four-way valve to be switched to a first state, the three-way valve to be switched to a third state, the first valve to be switched to a conducting state, the second valve to be switched to a stopping state, the first expansion valve to be in a full-open conducting state, and the second expansion valve to be in a forward throttling state, so that the main circulation loop operates in the single-stage compression heating mode;
the four-way valve is controlled to be switched to a first state, the three-way valve is switched to a fourth state, the first valve is switched to a cut-off state, the second valve is switched to a conducting state, the first expansion valve is in a forward throttling state, and the second expansion valve is in a forward throttling state, so that the main circulation loop and the air supply branch circuit are matched to operate in the two-stage compression heating mode;
and controlling the four-way valve to be switched to a second state, the three-way valve to be switched to a third state, the first valve to be switched to a conducting state, the second valve to be switched to a stopping state, the first expansion valve to be in a reverse throttling state, and the second expansion valve to be in a full-open conducting state, so that the main circulation loop operates in the single-stage compression refrigeration mode.
According to the control method of the air source heat pump provided by the invention, the method further comprises the following steps:
when the main circulation loop operates in the single-stage compression heating mode or when the main circulation loop and the air supply branch operate in a matching mode in the two-stage compression heating mode, the four-way valve is controlled to be switched to a second state, the three-way valve is controlled to be switched to a third state, the first valve is controlled to be switched to a conducting state, the second valve is controlled to be switched to a cut-off state, the first expansion valve is in a reverse throttling state, and the second expansion valve is controlled to be in a fully-opened conducting state, so that the main circulation loop operates in a defrosting mode.
The air source heat pump suitable for the severe cold area, provided by the invention, has the advantages that the first heat exchanger is used as an indoor heat exchanger, and the second heat exchanger is used as an outdoor heat exchanger. When the heating is required, the state of the four-way valve is switched to a first state, so that the circulating medium compressed by the first compressor and the second compressor is condensed and released heat through the first heat exchanger, and a heating mode is operated; when refrigeration is required, the state of the four-way valve is switched to the second state, so that the circulating medium passing through the first compressor and the second compressor is condensed and released heat through the second heat exchanger, the cooled circulating medium is throttled by the first expansion valve and then evaporated and absorbed heat through the first heat exchanger, and the refrigeration mode is operated, namely, the state of the four-way valve is switched, so that the free switching between the refrigeration mode and the heating mode can be realized. In the heating mode, when the temperature difference between the indoor and the outdoor in winter in severe cold areas is large and the requirement on the compression ratio is high, the first valve can be closed and the second valve can be opened by switching the state of the three-way valve to the fourth state, so that the circulating medium sequentially passes through the first compressor and the second compressor, and the two-stage compression mode is operated; when the indoor and outdoor temperature difference is smaller, the state to the third state through switching the three-way valve can be passed, open first valve, close the second valve, make first compressor and second compressor be parallelly connected and set up, operation single-stage compression mode, first compressor and second compressor all are in operating condition this moment, compress the circulating medium simultaneously, the idleness of compressor has been avoided, promptly through switching the three-way valve, the state of first valve and second valve, can realize the switching between doublestage compression mode and the single-stage compression mode, and under the single-stage compression mode, first compressor and second compressor all are in operating condition, there is not the compressor of idle state. The problem of have the compressor idle when can't switch or switch to the single-stage compression operating mode between double-stage compression operating mode and single-stage compression operating mode that double-stage compression system who has refrigeration mode and heating mode simultaneously among the prior art exists is solved.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of an air source heat pump suitable for severe cold regions according to the present invention;
FIG. 2 is a schematic diagram of the air source heat pump of the present invention in a single-stage compression heating mode of operation suitable for use in severe cold regions;
FIG. 3 is a schematic view of the air source heat pump suitable for severe cold regions according to the present invention in a two-stage compression heating mode;
FIG. 4 is a schematic diagram of the air source heat pump operating in a single-stage compression refrigeration mode for use in cold regions according to the present invention;
FIG. 5 is a schematic view of the air source heat pump in a defrosting mode suitable for severe cold regions according to the present invention;
reference numerals:
1: a first compressor; 2: a second compressor; 3: a four-way valve;
4: a first heat exchanger; 5: a first expansion valve; 6: a flash evaporator;
7: a second heat exchanger; 8: a second expansion valve; 9: a second valve;
10: a first valve; 11: and a three-way valve.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
An air source heat pump suitable for severe cold regions according to an embodiment of the invention is described below with reference to fig. 1 to 5.
As shown in fig. 1 to 5, an embodiment of the present invention provides an air source heat pump suitable for severe cold areas, including a main circulation loop and an air supply branch.
The main circulation loop comprises a compression assembly, a four-way valve 3, a first heat exchanger 4, a first expansion valve 5, a flash evaporator 6, a second expansion valve 8 and a second heat exchanger 7, wherein the first heat exchanger 4, the first expansion valve 5, the flash evaporator 6, the second expansion valve 8 and the second heat exchanger 7 are sequentially connected.
Referring to fig. 1, the four-way valve 3 has four ports, which are a port D, a port E, a port C, and a port S, specifically, the port D is connected to the exhaust end of the compression assembly, the port E is connected to the second heat exchanger 7, the port C is connected to the first heat exchanger 4, and the port S is connected to the suction end of the compression assembly. The four-way valve 3 can be switched between a first state and a second state, when the four-way valve 3 is switched to the first state, the D interface is communicated with the C interface, and the E interface is communicated with the S interface. When the four-way valve 3 is switched to the second state, the interface D is conducted with the interface E, and the interface S is conducted with the interface C.
The compression assembly comprises a first compressor 1, a second compressor 2, a three-way valve 11 and a first valve 10, specifically, the suction end of the first compressor 1 and the suction end of the second compressor 2 are connected with an S interface, and the exhaust end of the first compressor 1 and the exhaust end of the second compressor 2 are connected with a D interface. The first compressor 1 and the second compressor 2 compress the circulating media such as the refrigerant, and increase the pressure and the temperature of the circulating media, thereby creating conditions for the condensation process.
The three-way valve 11 has three ports that can be communicated with each other, which are an L port, an M port, and an N port, specifically, the L port is connected to the discharge end of the first compressor 1, the M port is connected to the D port, and the N port is connected to the suction end of the second compressor 2. The three-way valve 11 can be switched between a third state and a fourth state, when the three-way valve 11 is switched to the third state, the L port is communicated with the M port, the N port is in a stop state, and when the three-way valve 11 is switched to the fourth state, the L port is communicated with the N port, and the M port is in a stop state.
The first valve 10 is arranged between the air suction end and the S interface of the second compressor 2, when the first valve 10 is in a conducting state, the circulating medium flowing out through the S interface of the four-way valve 3 can directly enter the second compressor 2 while entering the first compressor 1; when the first valve 10 is in the off state, the circulating medium flowing out through the S port of the four-way valve 3 cannot directly enter the second compressor 2, but can only enter the suction end of the first compressor 1.
The flash evaporator 6 has three circulation ports, which are an X port, a Y port, and a Z port, respectively, a gaseous circulation medium is located in an upper space inside the flash evaporator 6, and a liquid circulation medium is located in a lower space inside the flash evaporator 6. The pipeline connected with the X connector and the pipeline connected with the Y connector extend below the liquid level of the liquid circulating medium, and the pipeline connected with the Z connector is communicated with the upper end of the flash evaporator 6.
The first expansion valve 5 is disposed between the flash evaporator 6 and the first heat exchanger 4, and is connected to the X port of the flash evaporator 6 and the first heat exchanger 4, respectively. The second expansion valve 8 is disposed between the flash evaporator 6 and the second heat exchanger 7, and is connected to the Y-port of the flash evaporator 6 and the second heat exchanger 7, respectively. The first expansion valve 5 and the second expansion valve 8 are expansion devices capable of realizing functions of forward throttling, reverse throttling, full-open conduction, and closing non-conduction, and the pressure of the circulating medium is reduced by the throttling action of the first expansion valve 5 and the second expansion valve 8.
The forward throttling function and the reverse throttling function of the first expansion valve 5 mean that throttling effect can be achieved both when the circulating medium flows in the forward direction and in the reverse direction in the first expansion valve 5, and the forward throttling function and the reverse throttling function of the second expansion valve 8 mean that throttling effect can be achieved both when the circulating medium flows in the forward direction and in the reverse direction in the second expansion valve 8.
The air supply branch is a connecting pipeline arranged between the flash evaporator 6 and the second compressor 2, specifically, one end of the air supply branch is connected with the Z interface of the flash evaporator 6, and the other end of the air supply branch is connected with the air suction end of the second compressor 2. And a second valve 9 is arranged on the air supply branch to control the on-off of the air supply branch. When the second valve 9 is opened, the gaseous circulation medium in the flash evaporator 6 can enter the second compressor 2, and when the second valve 9 is closed, the gaseous circulation medium in the flash evaporator 6 can be prevented from flowing into the second compressor 2.
When it is necessary to supplement the gaseous circulating medium to the suction side of the second compressor 2, the expansion valve located upstream of the flash tank may be adjusted to a throttling state before the circulating medium enters the flash tank, and the circulating medium is throttled and depressurized by the expansion valve. And after entering the flash tank, the throttled circulating medium is separated into gaseous circulating medium, and the gaseous circulating medium can be circulated to the air suction end of the second compressor 2 through the air supplementing branch and the second valve 9. When the gaseous circulating medium is not needed to be supplemented to the suction end of the second compressor 2, the expansion valve located upstream of the flash tank is adjusted to a fully open conducting state before the circulating medium enters the flash tank, the expansion valve has no throttling and pressure reducing effects on the circulating medium, and at the moment, the flash tank is only used as a liquid storage tank.
In a specific embodiment, when the air source heat pump in this embodiment is used as an air conditioner, the first heat exchanger 4 may be used as an indoor heat exchanger, and heat exchange is performed between the circulating medium and the indoor air to increase or decrease the temperature of the indoor air; the second heat exchanger 7 is made to function as an outdoor heat exchanger for performing heat exchange with the circulating medium using outdoor air to increase or decrease the temperature of the circulating medium.
In the case of a heating demand, the first heat exchanger 4 serves as a condenser, and the second heat exchanger 7 serves as an evaporator.
If the indoor and outdoor temperature difference is small, the state of the four-way valve 3 is switched to the first state, the state of the three-way valve 11 is switched to the third state, the first valve 10 is opened, the second valve 9 is closed, the first expansion valve 5 is adjusted to be in the full-open conducting state, and the second expansion valve 8 is adjusted to be in the forward throttling state, as shown in fig. 2. At this time, the first compressor 1 and the second compressor 2 are in a parallel state, the discharge end of the first compressor 1 and the discharge end of the second compressor 2 are connected to the first heat exchanger 4 through the D port and the C port of the four-way valve 3, and the second heat exchanger 7 is connected to the suction end of the first compressor 1 and the suction end of the second compressor 2 through the E port and the S port of the four-way valve 3. The circulation path of the circulation medium is as follows:
the circulating medium enters the first compressor 1 and the second compressor 2 at the same time, and after being compressed by the first compressor 1 and the second compressor 2, the pressure and the temperature are increased;
then the heat enters a first heat exchanger 4 through a D interface and a C interface of the four-way valve 3, condensation occurs in the first heat exchanger 4, heat is released to the indoor space, so that the indoor temperature is increased, and the temperature of a circulating medium is reduced;
then enters the flash tank through the first expansion valve 5 and an X interface of the flash tank, the first expansion valve 5 in a full-open conduction state has no throttling and pressure reducing effects on the circulating medium, so that the circulating medium directly flows out through a Y interface after entering the flash tank;
after passing through the second expansion valve 8 in the forward throttling state, the pressure of the circulating medium is reduced;
then the circulating medium enters a second heat exchanger 7, in the second heat exchanger 7, the circulating medium in a low-pressure state is evaporated by heat, the cold energy is transmitted to the outdoor space, and the temperature of the circulating medium is increased;
and then the circulating medium enters the first compressor 1 and the second compressor 2 through an E interface and an S interface of the four-way valve 3 for circulation.
Under the working condition, the circulating medium simultaneously enters the first compressor 1 and the second compressor 2 without the sequence, so that a single-stage compression heating mode is realized.
In winter in severe cold areas, the temperature difference between the indoor and the outdoor is large. When the indoor and outdoor temperature difference is large, the state of the four-way valve 3 is switched to the first state, the state of the three-way valve 11 is switched to the fourth state, the first valve 10 is closed, the second valve 9 is opened, and the first expansion valve 5 and the second expansion valve 8 are adjusted to be in the forward throttling state, as shown in fig. 3. At this time, the suction end of the second compressor 2 is connected to the discharge end of the first compressor 1, the discharge end of the second compressor 2 is connected to the first heat exchanger 4 through the D port and the C port of the four-way valve 3, the second heat exchanger 7 is connected to the suction end of the first compressor 1 through the E port and the S port of the four-way valve 3, and the first compressor 1 and the second compressor 2 are connected in series. The circulation path of the circulation medium is as follows:
the circulating medium enters the first compressor 1, and after the circulating medium is compressed by the first compressor 1, the pressure and the temperature are increased;
then the circulating medium enters the second compressor 2, and after being compressed by the second compressor 2, the pressure and the temperature are further increased;
the circulating medium compressed by the second compressor 2 enters the first heat exchanger 4 through a D interface and a C interface of the four-way valve 3, is condensed in the first heat exchanger 4, releases heat to the indoor space to increase the indoor temperature, and reduces the temperature of the circulating medium;
then the circulating medium enters the flash tank through the first expansion valve 5 and an X interface of the flash tank, the pressure of the circulating medium is reduced after the circulating medium passes through the first expansion valve 5 in a forward throttling state, the circulating medium is quickly gasified after entering the flash tank to generate a gaseous circulating medium, and the gaseous circulating medium rises to the upper space of the flash tank and is separated from a liquid circulating medium;
the liquid circulating medium flows out through the Y interface, and the gaseous circulating medium enters the air supplementing branch through the Z interface;
after the circulating medium flowing out of the Y interface passes through the second expansion valve 8 in a forward throttling state, the pressure of the circulating medium is reduced;
then the cold water enters a second heat exchanger 7, in the second heat exchanger 7, the circulating medium in a low-pressure state is evaporated by heat, the cold energy is transmitted to the outdoor, and the temperature of the circulating medium is increased;
then, the circulating medium enters the first compressor 1 through an E interface and an S interface of the four-way valve 3, and after the circulating medium is compressed by the first compressor 1, both the pressure and the temperature are increased;
the circulating medium compressed by the first compressor 1 and the gaseous circulating medium in the air supply branch enter the second compressor 2 at the same time, and are compressed by the second compressor 2 to circulate the paths.
Under the working condition, the circulating medium firstly enters the first compressor 1 and then enters the second compressor 2, so that a double-stage compression heating mode is realized. When the indoor and outdoor temperature difference is large, the problem of low efficiency caused by overlarge compression ratio is avoided, and the heat supply efficiency is improved.
In the case of a cooling demand, the first heat exchanger 4 serves as an evaporator, and the second heat exchanger 7 serves as a condenser. At this time, the state of the four-way valve 3 is switched to the second state, the state of the three-way valve 11 is switched to the third state, the first valve 10 is opened, the second valve 9 is closed, the first expansion valve 5 is adjusted to the reverse throttle state, and the second expansion valve 8 is adjusted to the full open conduction state, as shown in fig. 4. At this time, the first compressor 1 and the second compressor 2 are in a parallel state, the discharge end of the first compressor 1 and the discharge end of the second compressor 2 are connected to the second heat exchanger 7 through the D port and the E port of the four-way valve 3, and the first heat exchanger 4 is connected to the suction end of the first compressor 1 and the suction end of the second compressor 2 through the S port and the C port of the four-way valve 3. The circulation path of the circulation medium is as follows:
the circulating medium enters the first compressor 1 and the second compressor 2 at the same time, and after being compressed by the first compressor 1 and the second compressor 2, the pressure and the temperature are increased;
then enters a second heat exchanger 7 through a D interface and an E interface of the four-way valve 3, is condensed in the second heat exchanger 7, releases heat to the outdoor, and reduces the temperature of the circulating medium;
then enters the flash tank through a second expansion valve 8 and a Y interface of the flash tank, the second expansion valve 8 in a full-open conduction state has no throttling and pressure reducing effects on the circulating medium, so that the circulating medium directly flows out through the X interface after entering the flash tank;
after passing through the first expansion valve 5 in a reverse throttling state, the pressure of the circulating medium is reduced;
then the cold water enters a first heat exchanger 4, in the first heat exchanger 4, the circulating medium in a low-pressure state is evaporated by heat, the cold energy is transmitted to the indoor space, and the temperature of the circulating medium is increased;
and then the circulating medium enters the first compressor 1 and the second compressor 2 through a C interface and an S interface of the four-way valve 3 for circulation.
Under the working condition, the circulating medium simultaneously enters the first compressor 1 and the second compressor 2 without the sequence, so that the single-stage compression refrigeration mode is realized.
It should be noted that in summer in severe cold areas, the indoor and outdoor temperature difference is not too large, and the single-stage compression refrigeration mode can meet the use requirement.
In summary, by switching the state of the four-way valve 3, the free switching between the cooling mode and the heating mode can be realized, by switching the states of the three-way valve 11, the first valve 10 and the second valve 9, the switching between the two-stage compression mode and the single-stage compression mode can be realized, and in the single-stage compression mode, the first compressor 1 and the second compressor 2 are both in the working state, and there is no compressor in the idle state. The problem of have the compressor idle when can't switch or switch to the single-stage compression operating mode between double-stage compression operating mode and single-stage compression operating mode that double-stage compression system who has refrigeration mode and heating mode simultaneously among the prior art exists is solved.
The first compressor 1 and the second compressor 2 in the embodiment of the present invention may be two mutually independent compressors, or a double-suction double-row compressor may be used as the first compressor 1 and the second compressor 2, and the types of the equipment of the first compressor 1 and the second compressor 2 may be the same or different.
In the embodiment of the present invention, one first heat exchanger 4 and one second heat exchanger 7 may be provided, but in order to ensure the heat exchange effect of the first heat exchanger 4 and the second heat exchanger 7, a plurality of first heat exchangers 4 and a plurality of second heat exchangers 7 may be provided, the plurality of first heat exchangers 4 may be provided in a form of series connection, parallel connection or combination of series connection and parallel connection, and the plurality of second heat exchangers 7 may be provided in a form of series connection, parallel connection or combination of series connection and parallel connection, so that sufficient heat exchange may be ensured.
The first heat exchanger 4 may be a refrigerant-air heat exchanger or a refrigerant-water heat exchanger, depending on the heat exchange medium to exchange heat with the circulating medium. Specifically, the first heat exchanger 4 includes a first heat exchange channel and a second heat exchange channel, the first heat exchange channel is used for air or water to circulate, and the second heat exchange channel is used for refrigerant to circulate. Two ends of the second heat exchange channel are respectively connected with the interface C and the first expansion valve 5, and the first heat exchange channel is communicated with indoor air or a water source.
The second heat exchanger 7 may be a refrigerant-air heat exchanger. Specifically, the second heat exchanger 7 includes a third heat exchange path and a fourth heat exchange path through which air and refrigerant circulate, respectively. Two ends of the fourth heat exchange channel are respectively connected with the interface E and the second expansion valve 8, and the third heat exchange channel is communicated with outdoor air.
The air source heat pump suitable for the severe cold area in the embodiment of the invention further comprises a first fan and a second fan, or comprises a water pump and a second fan. The second fan is used for driving air to circulate in the third heat exchange channel so as to drive the air to circulate.
When the air source heat pump in the embodiment of the present invention is used to heat or cool air, a first fan is used to drive air to circulate in the first heat exchange channel of the first heat exchanger 4, so as to drive the circulation of air.
When the air source heat pump in the embodiment of the invention is used for heating or refrigerating water, the water pump is required to drive the water to circulate in the first heat exchange channel of the first heat exchanger 4 so as to drive the water to circulate.
In another aspect, the invention further provides an air conditioner, which includes the air source heat pump suitable for severe cold regions provided by any of the above embodiments. The air conditioner provided by the embodiment of the invention has a refrigerating mode and a heating mode, can be freely switched among a single-stage compression heating mode, a double-stage compression heating mode and a single-stage compression refrigerating mode, and the first compressor 1 and the second compressor 2 work simultaneously in the double-stage compression mode, so that the compressor is prevented from being idle. The problem of have the compressor idle when can't switch or switch to the single-stage compression operating mode between double-stage compression operating mode and single-stage compression operating mode that double-stage compression system who has refrigeration mode and heating mode simultaneously among the prior art exists is solved. The derivation process of the beneficial effect of the air conditioner in the embodiment of the present invention is substantially similar to the derivation process of the beneficial effect of the air source heat pump suitable for the severe cold region, and therefore, the details are not repeated here.
The air conditioner in the embodiment of the invention comprises a first shell and a second shell, wherein the first heat exchanger 4 is arranged in the first shell to form an indoor unit. The first compressor, the second compressor, the three-way valve 11, the first valve 10, the four-way valve 3, the first expansion valve 5, the flash evaporator 6, the second expansion valve 8, the second heat exchanger 7 and the second valve 9 are arranged in the second shell to form an outdoor unit. The number of the indoor units and the number of the outdoor units are respectively one, and the indoor units correspond to the outdoor units one to one. In addition, utilize first casing and second casing to carry out fixed mounting and protection to spare part, be favorable to increase of service life.
The air conditioner in the embodiment of the invention comprises a first shell and a second shell, wherein the first expansion valve 5 and the first heat exchanger 4 are arranged in the first shell to form an indoor unit. The first compressor, the second compressor, the three-way valve 11, the first valve 10, the four-way valve 3, the flash evaporator 6, the second expansion valve 8, the second heat exchanger 7 and the second valve 9 are arranged in the second shell to form an outdoor unit. Utilize first casing and second casing to carry out fixed mounting and protection to spare part, be favorable to increase of service life.
At least one indoor unit is arranged, and one outdoor unit is arranged. When the indoor units are arranged in plurality, each indoor unit is connected with the outdoor unit, namely, one outdoor unit can drive the indoor units to operate. The number of indoor units can be determined according to actual requirements. Corresponding first expansion valves 5 are arranged in each indoor unit, so that the indoor units can be independently controlled.
In another aspect, the invention further provides a control method capable of controlling the air source heat pump suitable for the severe cold region provided in any one of the above embodiments, so that the air source heat pump suitable for the severe cold region operates in a single-stage compression heating mode, a double-stage compression heating mode and a single-stage compression refrigeration mode respectively. The control method of the air source heat pump described below and the air source heat pump suitable for the severe cold region described above may be referred to in correspondence with each other.
The control method of the air source heat pump provided by the embodiment of the invention comprises the following steps:
controlling the four-way valve 3 to be switched to a first state, the three-way valve 11 to be switched to a third state, the first valve 10 to be switched to a conducting state, the second valve 9 to be switched to a stopping state, the first expansion valve 5 to be in a fully-opened conducting state, and the second expansion valve 8 to be in a forward throttling state, so that the main circulation loop operates in a single-stage compression heating mode;
controlling the four-way valve 3 to be switched to a first state, the three-way valve 11 to be switched to a fourth state, the first valve 10 to be switched to a cut-off state, the second valve 9 to be switched to a conducting state, the first expansion valve 5 to be in a forward throttling state, and the second expansion valve 8 to be in a forward throttling state, so that the main circulation loop and the air supply branch are matched to run in a double-stage compression heating mode;
the four-way valve 3 is controlled to be switched to a second state, the three-way valve 11 is controlled to be switched to a third state, the first valve 10 is controlled to be switched to a conducting state, the second valve 9 is controlled to be switched to a stopping state, the first expansion valve 5 is in a reverse throttling state, and the second expansion valve 8 is in a full-open conducting state, so that the main circulation loop operates in a single-stage compression refrigeration mode.
In the heating season, when the main circulation loop runs in a single-stage compression heating mode for a long time or the main circulation loop and the air supply branch run in a double-stage compression heating mode for a long time in a matching manner, the second heat exchanger 7 located outdoors is prone to frosting.
In order to achieve defrosting, the control method of the air source heat pump provided by the embodiment of the invention further comprises the following steps:
the four-way valve 3 is controlled to be switched to the second state, the three-way valve 11 is controlled to be switched to the third state, the first valve 10 is controlled to be switched to the on state, the second valve 9 is controlled to be switched to the off state, the first expansion valve 5 is controlled to be in the reverse throttle state, and the second expansion valve 8 is controlled to be in the full open on state, so that the main circulation circuit is operated as the defrosting mode, referring to fig. 5.
In the defrosting mode, the second heat exchanger 7 located outdoors is a condenser, and defrosting can be achieved by using the heat of condensation.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. The utility model provides an air source heat pump suitable for severe cold district which characterized in that, includes main circulation return circuit and tonifying qi branch road, wherein:
the main circulation loop comprises a compression assembly, a four-way valve, a first heat exchanger, a first expansion valve, a flash evaporator, a second expansion valve and a second heat exchanger which are sequentially connected;
the four-way valve is provided with a D interface connected with the exhaust end of the compression assembly, an E interface connected with the second heat exchanger, a C interface connected with the first heat exchanger and an S interface connected with the suction end of the compression assembly, and can be switched between a first state and a second state, wherein the D interface is communicated with the C interface and the E interface is communicated with the S interface in the first state, and the D interface is communicated with the E interface and the S interface is communicated with the C interface in the second state;
the compression assembly comprises a first compressor, a second compressor, a three-way valve and a first valve, wherein the air suction end of the first compressor and the air suction end of the second compressor are connected with an S interface, the air discharge end of the first compressor and the air discharge end of the second compressor are connected with a D interface, the three-way valve is provided with an L interface connected with the air discharge end of the first compressor, an M interface connected with the D interface and an N interface connected with the air suction end of the second compressor, the first valve is arranged between the air suction end of the second compressor and the S interface, when the first valve is in a conducting state, a circulating medium flowing out of the S interface can simultaneously enter the air suction end of the first compressor and the air suction end of the second compressor, and when the first valve is in a stopping state, the first valve limits that the circulating medium flowing out of the S interface can only directly enter the air suction end of the first compressor A terminal;
the three-way valve can be switched between a third state and a fourth state, wherein in the third state, the L interface is communicated with the M interface, the N interface is in a cut-off state, in the fourth state, the L interface is communicated with the N interface, and the M interface is in a cut-off state;
the flash vessel has X interface and the Y interface that supplies the liquid circulation and supplies the Z interface of gas circulation, first expansion valve with the second expansion valve respectively with the X interface with Y interface connection, first expansion valve with the second expansion valve can realize forward throttle, reverse throttle, open entirely and switch on and close non-conductive function, the one end of tonifying qi branch road with the flash vessel Z interface connection, the other end with the end connection of breathing in of second compressor, be provided with the second valve on the tonifying qi branch road, first expansion valve with lie in the second expansion valve when one on the flash vessel upper reaches and is in open entirely the conducting state, the flash vessel uses as the liquid storage pot.
2. The air-source heat pump suitable for severe cold regions of claim 1, wherein the first compressor and the second compressor are independent compressors, or the first compressor and the second compressor are integrated double-suction double-row compressors.
3. The air-source heat pump suitable for severe cold regions according to claim 1, wherein the first heat exchanger is provided in plurality, and the second heat exchanger is provided in plurality.
4. The air source heat pump suitable for severe cold regions according to claim 1, wherein the first heat exchanger comprises a first heat exchange channel for air or water circulation and a second heat exchange channel for circulation of a circulating medium, and two ends of the second heat exchange channel are respectively connected with the C interface and the first expansion valve;
the second heat exchanger comprises a third heat exchange channel for air circulation and a fourth heat exchange channel for circulation of a circulating medium, and two ends of the fourth heat exchange channel are respectively connected with the E interface and the second expansion valve.
5. The air-source heat pump suitable for severe cold regions according to claim 4, further comprising:
the first fan or the water pump is used for driving air or water to circulate in the first heat exchange channel;
and the second fan is used for driving air to circulate in the third heat exchange channel.
6. An air conditioner, characterized in that, comprising the air source heat pump suitable for severe cold areas according to any one of claims 1-5.
7. The air conditioner according to claim 6, wherein the air conditioner comprises a first casing and a second casing, wherein the first casing is provided with a first heat exchanger therein to form an indoor unit, the second casing is provided with a first compressor, a second compressor, a three-way valve, a first valve, a four-way valve, a first expansion valve, a flash evaporator, a second expansion valve, a second heat exchanger, and a second valve therein to form an outdoor unit, and the indoor unit is connected to the outdoor unit.
8. The air conditioner of claim 6, wherein the air conditioner comprises a first casing and a second casing, the first casing having a first expansion valve and a first heat exchanger disposed therein to constitute an indoor unit, the second casing having a first compressor, a second compressor, a three-way valve, a first valve, a four-way valve, a flash evaporator, a second expansion valve, a second heat exchanger, and a second valve disposed therein to constitute an outdoor unit,
the indoor unit is provided with at least one, and the outdoor unit is provided with one, and the indoor unit is connected with the outdoor unit.
9. A control method of an air source heat pump, which is characterized in that the air source heat pump suitable for severe cold regions according to any one of claims 1 to 5 can be controlled to operate in a single-stage compression heating mode, a double-stage compression heating mode and a single-stage compression refrigerating mode respectively, and the control method comprises the following steps:
controlling the four-way valve to be switched to a first state, the three-way valve to be switched to a third state, the first valve to be switched to a conducting state, the second valve to be switched to a stopping state, the first expansion valve to be in a full-open conducting state, and the second expansion valve to be in a forward throttling state, so that the main circulation loop is operated in the single-stage compression heating mode;
the four-way valve is controlled to be switched to a first state, the three-way valve is switched to a fourth state, the first valve is switched to a cut-off state, the second valve is switched to a conducting state, the first expansion valve is in a forward throttling state, and the second expansion valve is in a forward throttling state, so that the main circulation loop and the air supply branch circuit are matched to operate in the two-stage compression heating mode;
and controlling the four-way valve to be switched to a second state, the three-way valve to be switched to a third state, the first valve to be switched to a conducting state, the second valve to be switched to a stopping state, the first expansion valve to be in a reverse throttling state, and the second expansion valve to be in a full-open conducting state, so that the main circulation loop operates in the single-stage compression refrigeration mode.
10. The control method of the air source heat pump according to claim 9, further comprising:
when the main circulation loop operates in the single-stage compression heating mode or when the main circulation loop and the air supply branch operate in a matching mode in the two-stage compression heating mode, the four-way valve is controlled to be switched to a second state, the three-way valve is controlled to be switched to a third state, the first valve is controlled to be switched to a conducting state, the second valve is controlled to be switched to a stopping state, the first expansion valve is in a reverse throttling state, and the second expansion valve is controlled to be in a full-open conducting state, so that the main circulation loop operates in the defrosting mode.
CN202110963403.6A 2021-08-20 2021-08-20 Air source heat pump, air conditioner and control method suitable for severe cold area Active CN113776219B (en)

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CN114183862B (en) * 2021-12-21 2023-03-28 宁波奥克斯电气股份有限公司 Air conditioning system with single-stage compression switching function and double-stage compression switching control method
CN114791181A (en) * 2022-04-18 2022-07-26 东南大学 Two-stage compressed air source heat pump system based on oil balancing oil way balancing device
CN115560493A (en) * 2022-11-07 2023-01-03 珠海格力电器股份有限公司 Heat pump system and control method of heat pump system

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