CN108518892B - Air source heat pump system-based air supply control device and control method thereof - Google Patents

Air source heat pump system-based air supply control device and control method thereof Download PDF

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Publication number
CN108518892B
CN108518892B CN201810414822.2A CN201810414822A CN108518892B CN 108518892 B CN108518892 B CN 108518892B CN 201810414822 A CN201810414822 A CN 201810414822A CN 108518892 B CN108518892 B CN 108518892B
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air
expansion valve
electronic expansion
temperature
heat exchanger
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CN108518892A (en
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徐洪波
韩欣欣
田长青
邹慧明
尤立伟
康伟
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Technical Institute of Physics and Chemistry of CAS
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Technical Institute of Physics and Chemistry of CAS
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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
    • F25B30/00—Heat pumps
    • F25B30/02—Heat pumps of the compression type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • F25B41/31—Expansion valves
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The invention relates to the technical field of air source heat pumps, and discloses an air supplementing control device based on an air source heat pump system and a control method thereof, wherein if the outdoor environment temperature is less than or equal to a preset value, air supplementing is performed; in the air supplementing mode, when the heating quantity can meet the heat demand, controlling the opening of the electronic expansion valve of the air supplementing branch according to the COP optimal criterion and the exhaust superheat degree; and when the heating quantity can not meet the heat demand, controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum criterion of the heating quantity and the superheat degree of the exhaust. According to the invention, under different working conditions, different heating control methods are adopted to control the opening degree of the electronic expansion valve of the air supplementing branch, so that the exhaust temperature is not too low, the heat pump system can always maintain the excellent comprehensive heating performance, the heating capacity is improved as much as possible in a low-temperature environment, the system is ensured to have higher heating performance, the energy consumption is reduced, and the system safety is improved.

Description

Air source heat pump system-based air supply control device and control method thereof
Technical Field
The invention relates to the technical field of air source heat pumps, in particular to an air supplementing control device based on an air source heat pump system and a control method thereof.
Background
The heating capacity of a common single-stage compressed air source heat pump system is seriously attenuated along with the reduction of the outdoor environment temperature, and even the system cannot work normally at extremely low temperature, but the lower the environment temperature is, the larger the heating capacity requirement of a building or a vehicle on a heat pump unit is, and the single-stage compressed heat pump unit cannot meet the requirements of heating capacity and reliability. The air source heat pump system with the middle air supplementing adopts a quasi-secondary compression mode, so that the heating capacity can be improved in a low-temperature environment, the exhaust temperature of the compressor can be reduced, and the system can be operated safely and reliably, so that the system becomes a research hot spot.
For the air source heat pump system with middle air supplementing, the opening degree of the electronic expansion valve of the air supplementing branch directly influences the air supplementing pressure, the air supplementing quantity and the state of air supplementing points, and further influences the heating quantity, the exhaust temperature and the heating performance of the system, so that the control of the opening degree of the electronic expansion valve of the air supplementing branch is very important to the whole system.
According to the investigation result of the publication, as the opening of the electronic expansion valve of the air supplementing branch is increased, the heating capacity of the heat pump system is continuously increased, and an optimal value exists in the system COP (coefficient of performance ). In a low-temperature environment, not only the heating COP of the heat pump system but also the heating quantity of the heat pump system are concerned, because the heating quantity of the heat pump unit is generally required to be larger by the low-temperature environment, and if the heating quantity requirement is not met, only auxiliary electric heating can be adopted. In addition, as the opening of the electronic expansion valve of the air supplementing branch is increased, the exhaust temperature of the compressor is gradually reduced, and when the exhaust temperature of the compressor is too low, the safe operation of the heat pump system is affected. Therefore, the common methods for controlling the superheat degree of the air supplementing branch and the exhaust superheat degree at present can not lead the heat pump system to always run according to the better heating performance under different working conditions.
Disclosure of Invention
First, the technical problem to be solved
The invention aims to provide an air-supplementing control device based on an air source heat pump system and a control method thereof, which solve the problems that the superheat degree control of an air-supplementing branch and the superheat degree control method of exhaust in the prior art can not always maintain higher heating performance and improve the safety performance of the system under different working conditions.
(II) technical scheme
In order to solve the above technical problems, the present invention provides an air supply control device based on an air source heat pump system, comprising: the system comprises a compressor, a four-way reversing valve, an indoor heat exchanger, an outdoor heat exchanger, an intermediate heat exchanger, a gas-liquid separator, a main way electronic expansion valve, a one-way valve and a gas supplementing branch electronic expansion valve, wherein the first end of the compressor is connected with the first end of the four-way reversing valve, the second end of the compressor is connected with the second end of the four-way reversing valve through the gas-liquid separator, the first end of the outdoor heat exchanger is connected with the first end of the main way electronic expansion valve, the first end of the indoor heat exchanger is connected with the second end of the main way electronic expansion valve through the first side of the intermediate heat exchanger, the second end of the indoor heat exchanger is connected with the third end of the four-way reversing valve, the second end of the outdoor heat exchanger is connected with the second side of the intermediate heat exchanger through the one-way valve, and the branch electronic expansion valve is further connected between the second side of the intermediate heat exchanger and the first end of the indoor heat exchanger;
the indoor heat exchanger is provided with a first temperature measuring device for measuring air inlet temperature and a second temperature measuring device for measuring air outlet temperature, the compressor is provided with a third temperature measuring device for measuring exhaust temperature, the outdoor heat exchanger is provided with a fourth temperature measuring device for measuring outdoor environment side temperature, and the compressor is provided with a pressure measuring device for measuring exhaust pressure and a current measuring device for measuring input current.
The compressor is a variable frequency compressor, the compressor is further provided with a frequency measuring device for measuring frequency, and the indoor environment applied by the heat pump system is further provided with a fifth temperature measuring device for measuring the side temperature of the indoor environment.
The invention also discloses a control method of the air supply control device based on the air source heat pump system, which comprises the following steps:
s1, measuring the inlet air temperature t of an indoor heat exchanger by using a first temperature measuring device ni Measuring the air outlet temperature t of the indoor heat exchanger by using a second temperature measuring device no Measuring the discharge temperature t of the compressor by means of a third temperature measuring device p Measuring the outdoor ambient side temperature t of the outdoor heat exchanger by using a fourth temperature measuring device ao The discharge pressure P of the compressor is measured by a pressure measuring device and a current measuring device p The initial opening of the electronic expansion valve of the air supplementing branch is set by inputting current I;
s2, if t ao >A, closing an electronic expansion valve of the air supplementing branch; if t ao If the pressure is less than or equal to A, opening an electronic expansion valve of the air supplementing branch circuit, and operating in an air supplementing mode; wherein A represents a conversion temperature constant of an air source heat pump system in an air supplementing and non-air supplementing mode;
s3, under the operation of the air supplementing mode, when the heating quantity can meet the heat requirement, controlling the opening of the electronic expansion valve of the air supplementing branch according to the COP optimal criterion and the exhaust superheat degree;
and under the operation of the air supplementing mode, when the heating quantity can not meet the heat demand, controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the exhaust superheat degree.
Under the operation of the air supplementing mode, when the heating quantity can meet the heat demand, controlling the opening of the electronic expansion valve of the air supplementing branch according to the COP optimal criterion and the exhaust superheat degree comprises the following steps:
s311, ifThe opening of the electronic expansion valve of the air supplementing branch is kept unchanged as the last opening, wherein I i Representing the input current of the ith compressor, I i-1 Represents the input current, Δt, of the i-1 th compressor n Represents the temperature difference delta t of the inlet and outlet air of the indoor heat exchanger n ＝t no -t ni ，(Δt n ) i Represents the temperature difference (delta t) of the inlet and outlet air of the ith indoor heat exchanger n ) i-1 Represents the temperature difference of the inlet air and the outlet air of the indoor heat exchanger of the ith-1 th time;
if it isThen according to the formula deltat p ＝t p -t ps Calculating Δt p Jump to step S312, where t ps Representing the compressor at discharge pressure P p A saturation temperature below;
s312, if Δt p >B, increasing the opening of the electronic expansion valve of the air supplementing branch;
if delta t p B is not more than or equal to the last opening degree of the electronic expansion valve of the air supplementing branch, wherein B represents the lowest set value of the superheat degree of the exhaust;
s313, repeating the steps S311-S312 after the time interval delta tau.
When the heating quantity can not meet the heat demand in the operation of the air supplementing mode, controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the exhaust superheat degree comprises the following steps:
s321, if (Δt) n ) i ≤(Δt n ) i-1 The opening of the electronic expansion valve of the air supplementing branch is kept unchanged as the last opening, wherein deltat n Represents the temperature difference delta t of the inlet and outlet air of the indoor heat exchanger n ＝t no -t ni ，(Δt n ) i Represents the temperature difference (delta t) of the inlet and outlet air of the ith indoor heat exchanger n ) i-1 Represents the temperature difference of the inlet air and the outlet air of the indoor heat exchanger of the ith-1 th time;
if (Deltat) n ) i >(Δt n ) i-1 Then according to the formula deltat p ＝t p -t ps Calculating Δt p Jump to step S322;
s322, if Δt p >B, increasing the opening of the electronic expansion valve of the air supplementing branch;
if delta t p B is not more than or equal to the last opening degree of the electronic expansion valve of the air supplementing branch, wherein B represents the lowest set value of the superheat degree of the exhaust;
s323, repeating the steps S321-S322 after the time interval delta tau.
Wherein, the S3 further comprises:
s301, measuring the frequency f of the compressor by using a frequency measuring device, and measuring the indoor environment side temperature t by using a fifth temperature measuring device an According to formula t an -t an-set ＝Δt an Calculating to obtain Deltat an Wherein t is an-set A set value for the indoor environment side temperature;
s302, if Δt an Judging whether the frequency f of the compressor is the maximum value or not, if so, increasing the opening of the electronic expansion valve of the air supplementing branch, and controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the superheat degree of the exhaust; if not, repeating the steps S301 and S302 after increasing the frequency of the compressor;
if-2 is less than or equal to deltat an The opening of the electronic expansion valve of the air supplementing branch is controlled according to the COP optimal criterion and the exhaust superheat degree after the opening of the electronic expansion valve of the air supplementing branch is increased to be less than or equal to 2;
if delta t an And (2), reducing the frequency of the compressor, and repeating the steps S301 and S302.
The switching temperature constant A of the air source heat pump system in the air-supplementing and non-air-supplementing modes is set to be 0 ℃, and the lowest set value B of the exhaust superheat degree is set to be 20 ℃.
And setting the initial opening degree of the electronic expansion valve of the air supplementing branch to be 0.1.
(III) beneficial effects
According to the air source heat pump system-based air supplementing control device and the air source heat pump system-based air supplementing control method, different heating control methods are adopted under different working conditions, the opening degree of the air supplementing branch electronic expansion valve is controlled, the exhaust temperature can be kept not to be too low, the heat pump system can always keep better comprehensive heating performance, the heating quantity is improved as much as possible in a low-temperature environment, meanwhile, the system is guaranteed to have higher heating performance, the energy consumption is reduced, and the system safety is improved.
Drawings
FIG. 1 is a schematic diagram of a structure of an air supply control device based on an air source heat pump system of the present invention;
FIG. 2 is a flow chart of controlling the opening of the electronic expansion valve of the air supplementing branch according to the COP optimal criterion and the exhaust superheat degree;
FIG. 3 is a flow chart of controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the superheat degree of the exhaust gas;
fig. 4 is a flowchart of embodiment 1 of the present invention.
In the figure, 1, a compressor; 2. a four-way reversing valve; 3. an indoor heat exchanger; 4. an intermediate heat exchanger; 5. a main electronic expansion valve; 6. an electronic expansion valve of the air supplementing branch; 7. an outdoor heat exchanger; 8. a gas-liquid separator; 9. a one-way valve; I. a compressor input current; f. compressor frequency; t is t p The discharge temperature of the compressor; p (P) p Discharge pressure of the compressor; t is t ao The outdoor environment side temperature of the outdoor heat exchanger; t is t ni The air inlet temperature of the indoor heat exchanger; t is t no And the air outlet temperature of the indoor heat exchanger.
Detailed Description
The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
As shown in fig. 1, the present invention discloses an air supply control device based on an air source heat pump system, comprising: the system comprises a compressor 1, a four-way reversing valve 2, an indoor heat exchanger 3, an outdoor heat exchanger 7, an intermediate heat exchanger 4, a gas-liquid separator 8, a main electronic expansion valve 5, a one-way valve 9 and a gas supplementing branch electronic expansion valve 6, wherein a first end of the compressor 1 is connected with a first end of the four-way reversing valve 2, a second end of the compressor 1 is connected with a second end of the four-way reversing valve 2 through the gas-liquid separator 8, a first end of the outdoor heat exchanger 7 is connected with a first end of the main electronic expansion valve 5, a first end of the indoor heat exchanger 3 is connected with a second end of the main electronic expansion valve 5 through a first side of the intermediate heat exchanger 4, a second end of the indoor heat exchanger 3 is connected with a third end of the four-way reversing valve 2, a second end of the outdoor heat exchanger 7 is connected with a fourth end of the four-way reversing valve 2, a third end of the compressor 1 is connected with a second side of the intermediate heat exchanger 4 through the one-way valve 9, and a third end of the indoor heat exchanger 3 is connected with a second side of the intermediate heat exchanger 4, and the expansion valve is connected between the second side of the indoor heat exchanger 3 and the auxiliary electronic expansion valve 6;
wherein the indoor heat exchanger 3 is provided with a first temperature measuring device for measuring the inlet air temperature and a second temperature measuring device for measuring the outlet air temperature, the compressor 1 is provided with a third temperature measuring device for measuring the outlet air temperature, the outdoor heat exchanger 7 is provided with a fourth temperature measuring device for measuring the outdoor environment side temperature, and the compressor 1 is provided with a pressure measuring device for measuring the outlet air pressure and a current measuring device for measuring the input current.
The temperature measuring device can adopt a temperature sensor, the pressure measuring device can adopt a pressure meter, the current measuring device can adopt an ammeter to measure, measured information is uploaded to the control system, the temperature measuring device is judged by a control method of the control system, and an instruction is sent to control the opening of the electronic expansion valve of the air supplementing branch, so that the opening control of the electronic expansion valve of the air supplementing branch is realized under different working conditions, and the electronic expansion valve of the air supplementing branch can control the air supplementing state of the air source heat pump system. Wherein, the medium in the indoor heat exchanger which exchanges heat with the refrigerant is air.
Specifically, the compressor is a variable frequency compressor, the compressor is further provided with a frequency measuring device for measuring frequency, and the indoor environment applied by the heat pump system is further provided with a fifth temperature measuring device for measuring the side temperature of the indoor environment. The frequency of the compressor may be controlled according to a difference between the indoor ambient side temperature of the outdoor heat exchanger and a preset temperature.
As shown in fig. 2-4, the invention further discloses a control method of the air supply control device based on the air source heat pump system, which comprises the following steps:
s1, use ofThe first temperature measuring device measures the inlet air temperature t of the indoor heat exchanger ni Measuring the air outlet temperature t of the indoor heat exchanger by using a second temperature measuring device no Measuring the discharge temperature t of the compressor by means of a third temperature measuring device p Measuring the outdoor ambient side temperature t of the outdoor heat exchanger by using a fourth temperature measuring device ao The discharge pressure P of the compressor is measured by a pressure measuring device and a current measuring device p The initial opening of the electronic expansion valve of the air supplementing branch is set by inputting current I;
s2, if t ao >A, closing an electronic expansion valve of the air supplementing branch; if t ao If the pressure is less than or equal to A, opening an electronic expansion valve of the air supplementing branch circuit, and operating in an air supplementing mode; wherein A represents a conversion temperature constant of an air source heat pump system in an air supplementing and non-air supplementing mode;
s3, under the operation of the air supplementing mode, when the heating quantity can meet the heat requirement, controlling the opening of the electronic expansion valve of the air supplementing branch according to the COP optimal criterion and the exhaust superheat degree;
and under the operation of the air supplementing mode, when the heating quantity can not meet the heat demand, controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the exhaust superheat degree.
According to the air source heat pump system-based air supplementing control device and the air source heat pump system-based air supplementing control method, different heating control methods are adopted under different working conditions, the opening degree of the air supplementing branch electronic expansion valve is controlled, the exhaust temperature can be kept not to be too low, the heat pump system can always keep better comprehensive heating performance, the heating quantity is improved as much as possible in a low-temperature environment, meanwhile, the system is guaranteed to have higher heating performance, the energy consumption is reduced, and the system safety is improved.
Specifically, the judgment formula and the calculation method according to the COP optimal criterion are as follows:
wherein I and I-1 respectively represent the opening degrees of the current and last air compensating valves, I i Representing the input current of the ith compressor, I i-1 Represents the input current of the i-1 th compressor, U is the input voltage of the compressor, c is the specific heat of air, m is the circulating air quantity, t ni The air inlet temperature t of the indoor heat exchanger no Is the air outlet temperature of the indoor heat exchanger.
Because the input voltage, the specific heat of air and the circulating air quantity of the medium-pressure compressor are all constant, the temperature difference (t no -t ni ) Is denoted as (Δt) n ) The following decision equation is obtained:
degree of superheat deltat of exhaust gas p The calculation formula of (2) is as follows:
Δt p ＝t p -t ps
wherein Δt is p Is the superheat degree of exhaust, t p T is the compressor discharge temperature ps For the exhaust pressure P p Saturation temperature below.
When the set value of the degree of superheat of the exhaust gas is denoted as a constant B, the determination formula of the degree of superheat of the exhaust gas is:
Δt p >B
therefore, as shown in fig. 2, in the operation of the air-supplementing mode, when the heating amount can satisfy the heat demand, controlling the opening degree of the air-supplementing branch electronic expansion valve according to the COP optimum criterion and the degree of superheat of the exhaust gas includes:
s311, ifThe opening of the electronic expansion valve of the air supplementing branch is kept unchanged as the last opening, wherein I i Representing the input current of the ith compressor, I i-1 Represents the input current, Δt, of the i-1 th compressor n Represents the temperature difference delta t of the inlet and outlet air of the indoor heat exchanger n ＝t no -t ni ，(Δt n ) i Represents the temperature difference (delta t) of the inlet and outlet air of the ith indoor heat exchanger n ) i-1 Represents the i-1 st indoorTemperature difference of inlet air and outlet air of the heat exchanger;
if it isThen according to the formula deltat p ＝t p -t ps Calculating Δt p Jump to step S312, where t ps Representing the compressor at discharge pressure P p A saturation temperature below;
s312, if Δt p >B, increasing the opening of the electronic expansion valve of the air supplementing branch;
if delta t p B is not more than or equal to the opening of the electronic expansion valve of the air supplementing branch is kept unchanged at the last opening;
s313, repeating the steps S311-S312 after the time interval delta tau.
Specifically, the decision formula according to the heating amount maximum criterion is:
Q i >Q i-1
cm*(t no -t ni ) i >cm*(t no -t ni ) i-1
wherein i and i-1 respectively represent the opening degrees of the current and last air compensating valves, c is the specific heat of air, m is the air quantity, and t ni The air inlet temperature t of the indoor heat exchanger no Is the air outlet temperature of the indoor heat exchanger.
Because the specific heat and the circulating air volume of the air are constant, the temperature difference (t no -t ni ) Is denoted as (Δt) n ) The following decision equation is obtained:
(Δt n ) i >(Δt n ) i-1
therefore, in the operation of the air-supplementing mode, when the heating amount cannot meet the heat demand, controlling the opening of the air-supplementing branch electronic expansion valve according to the heating amount maximum criterion and the exhaust superheat degree includes:
s321, if (Δt) n ) i ≤(Δt n ) i-1 The opening of the electronic expansion valve of the air supplementing branch is kept unchanged as the last opening, wherein deltat n Representing the temperature difference between the inlet and outlet air of the indoor heat exchanger，Δt n ＝t no -t ni ，(Δt n ) i Represents the temperature difference (delta t) of the inlet and outlet air of the ith indoor heat exchanger n ) i-1 Represents the temperature difference of the inlet air and the outlet air of the indoor heat exchanger of the ith-1 th time;
if (Deltat) n ) i >(Δt n ) i-1 Then according to the formula deltat p ＝t p -t ps Calculating Δt p Jump to step S322;
s322, if Δt p >B, increasing the opening of the electronic expansion valve of the air supplementing branch;
if delta t p B is not more than or equal to the opening of the electronic expansion valve of the air supplementing branch is kept unchanged at the last opening;
s323, repeating the steps S321-S322 after the time interval delta tau.
Specifically, step S3 further includes:
s301, measuring the frequency f of the compressor by using a frequency measuring device, and measuring the indoor environment side temperature t by using a fifth temperature measuring device an According to formula t an -t an-set＝ Δt an Calculating to obtain Deltat an Wherein t is an-set A set value for the indoor environment side temperature;
s302, if Δt an Judging whether the frequency f of the compressor is the maximum value or not, if so, increasing the opening of the electronic expansion valve of the air supplementing branch, and controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the superheat degree of the exhaust; if not, repeating the steps S301 and S302 after increasing the frequency of the compressor;
if-2 is less than or equal to deltat an The opening of the electronic expansion valve of the air supplementing branch is controlled according to the COP optimal criterion and the exhaust superheat degree after the opening of the electronic expansion valve of the air supplementing branch is increased to be less than or equal to 2;
if delta t an And (2), reducing the frequency of the compressor, and repeating the steps S301 and S302.
Based on Δt above an Can judge whether the heating quantity meets the heat requirement, and adjust the frequency of the compressor and the opening of the electronic expansion valve of the air supplementing branch by the heating quantityAlways keeps higher heating performance and improves the safety performance of the system.
Specifically, the switching temperature constant a of the air source heat pump system in the air-supplementing and non-air-supplementing modes is set to 0 ℃, and the lowest set value B of the exhaust superheat degree is set to 20 ℃.
Specifically, the initial opening of the electronic expansion valve of the air supplementing branch is set to be 0.1.
For ease of understanding, EEV in fig. 2-3 represents the air-make-up branch electronic expansion valve, Δeev is a preset increase in the opening of the air-make-up branch electronic expansion valve.
Example 1:
as shown in fig. 4, the control method provided by the invention is applied to a winter heating control scheme of an air source heat pump system with middle air supplement by adopting a variable frequency compressor. The specific control method comprises the following steps:
i, after the air source heat pump unit operates, firstly judging t ao >Whether A is true or not, where t ao For outdoor environment temperature, A is the switching temperature of the air-supplementing and non-air-supplementing modes of the heat pump unit, if the judgment is true, the electronic expansion valve of the air-supplementing branch is closed, and according to deltat an Controlling the frequency f of the compressor, and if the frequency f is not satisfied, entering a step II;
II, the unit takes the maximum frequency f max Starting, and setting the initial opening of the electronic expansion valve of the air supplementing branch to be 0.1. After a period of time Deltaτ passes, determining the indoor environment side temperature t measured by the fifth temperature measuring device an Set value t with indoor environment temperature an-set Difference delta t an 。
III if Δt an <-2, go to step IV, if-2. Ltoreq.Δt an Less than or equal to 2, go to step V, if Δt an >2, decreasing the frequency by CHz, repeating Δt an Is determined by the (a).
IV, firstly judging f=f max If not, repeating delta t after increasing DHz the frequency an Is determined by (a); if so, the opening of the electronic expansion valve for air supply is increased by ΔEEV, and then (Δt) is determined n ) i >(Δt n ) i-1 If not, setting the opening of the electronic expansion valve of the air supplementing branch to be unchanged from the last opening; if yes, then judging deltat p >B is established, if not, the opening of the electronic expansion valve of the air supplementing branch is set to be unchanged from the last opening; if yes, the opening of the electronic expansion valve of the air supplementing branch is increased by delta EEV (the step is to control the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the superheat degree of the exhaust).
V, increasing the opening of the air supplementing electronic expansion valve by delta EEV, and then judgingIf not, setting the opening of the electronic expansion valve of the air supplementing branch to be unchanged from the last opening; if yes, then judging deltat p >B is established, if not, the opening of the electronic expansion valve of the air supplementing branch is set to be unchanged from the last opening; if so, the opening of the electronic expansion valve of the air supplementing branch is increased by delta EEV (the step is to control the opening of the electronic expansion valve of the air supplementing branch according to the COP optimal criterion and the superheat degree of the exhaust).
VI, when outdoor environment temperature t ao If there is a large change, the EEV2 opening is set to 0.1, and the step III is re-entered to make a new determination.
The switching temperature A of the air-supplying and non-air-supplying modes of the heat pump unit in the embodiment is generally set to 0 ℃, the minimum setting value B of the superheat degree of the exhaust gas is generally set to 20 ℃, and the decrease value C and the increase value D of the compressor frequency are generally set according to the difference delta t between the indoor temperature and the setting temperature an Is determined by the size of (a). In fig. 4, EEV2 represents the electronic expansion valve of the air supply branch, and Δeev is a preset increase value of the opening of the electronic expansion valve of the air supply branch.
According to the air source heat pump system-based air supplementing control device and the air source heat pump system-based air supplementing control method, different heating control methods are adopted under different working conditions, the opening degree of the air supplementing branch electronic expansion valve is controlled, the exhaust temperature can be kept not to be too low, the heat pump system can always keep better comprehensive heating performance, the heating quantity is improved as much as possible in a low-temperature environment, meanwhile, the system is guaranteed to have higher heating performance, the energy consumption is reduced, and the system safety is improved.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (5)

1. A control method of an air supply control device based on an air source heat pump system, comprising:
s1, measuring the inlet air temperature t of an indoor heat exchanger by using a first temperature measuring device ni Measuring the air outlet temperature t of the indoor heat exchanger by using a second temperature measuring device no Measuring the discharge temperature t of the compressor by means of a third temperature measuring device p Measuring the outdoor ambient side temperature t of the outdoor heat exchanger by using a fourth temperature measuring device ao The discharge pressure P of the compressor is measured by a pressure measuring device and a current measuring device p The initial opening of the electronic expansion valve of the air supplementing branch is set by inputting current I;
s2, if t ao >A, closing an electronic expansion valve of the air supplementing branch; if t ao If the pressure is less than or equal to A, opening an electronic expansion valve of the air supplementing branch circuit, and operating in an air supplementing mode; wherein A represents a conversion temperature constant of an air source heat pump system in an air supplementing and non-air supplementing mode;
s3, under the operation of the air supplementing mode, when the heating quantity can meet the heat requirement, controlling the opening of the electronic expansion valve of the air supplementing branch according to the COP optimal criterion and the exhaust superheat degree;
when the heating quantity can not meet the heat demand under the operation of the air supplementing mode, controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the exhaust superheat degree;
under the operation of the air supplementing mode, when the heating quantity can meet the heat demand, controlling the opening of the air supplementing branch electronic expansion valve according to the COP optimal criterion and the exhaust superheat degree comprises the following steps:
s311, ifThe opening of the electronic expansion valve of the air supplementing branch is kept unchanged as the last opening, wherein I i Representing the input current of the ith compressor, I i-1 Represents the input current, Δt, of the i-1 th compressor n Represents the temperature difference delta t of the inlet and outlet air of the indoor heat exchanger n ＝t no -t ni ，(Δt n ) i Represents the temperature difference (delta t) of the inlet and outlet air of the ith indoor heat exchanger n ) i-1 Represents the temperature difference of the inlet air and the outlet air of the indoor heat exchanger of the ith-1 th time;
if it isThen according to the formula deltat p ＝t p -t ps Calculating Δt p Jump to step S312, where t ps Representing the compressor at discharge pressure P p A saturation temperature below;
s312, if Δt p >B, increasing the opening of the electronic expansion valve of the air supplementing branch;
if delta t p B is not more than or equal to the last opening degree of the electronic expansion valve of the air supplementing branch, wherein B represents the lowest set value of the superheat degree of the exhaust;
s313, repeating the steps S311-S312 after the time interval delta tau is passed;
wherein, air supply controlling means based on air source heat pump system includes: the system comprises a compressor, a four-way reversing valve, an indoor heat exchanger, an outdoor heat exchanger, an intermediate heat exchanger, a gas-liquid separator, a main way electronic expansion valve, a one-way valve and a gas supplementing branch electronic expansion valve, wherein the first end of the compressor is connected with the first end of the four-way reversing valve, the second end of the compressor is connected with the second end of the four-way reversing valve through the gas-liquid separator, the first end of the outdoor heat exchanger is connected with the first end of the main way electronic expansion valve, the first end of the indoor heat exchanger is connected with the second end of the main way electronic expansion valve through the first side of the intermediate heat exchanger, the second end of the indoor heat exchanger is connected with the third end of the four-way reversing valve, the second end of the outdoor heat exchanger is connected with the second side of the intermediate heat exchanger through the one-way valve, and the branch electronic expansion valve is further connected between the second side of the intermediate heat exchanger and the first end of the indoor heat exchanger;
the indoor heat exchanger is provided with a first temperature measuring device for measuring air inlet temperature and a second temperature measuring device for measuring air outlet temperature, the compressor is provided with a third temperature measuring device for measuring exhaust temperature, the outdoor heat exchanger is provided with a fourth temperature measuring device for measuring outdoor environment side temperature, and the compressor is provided with a pressure measuring device for measuring exhaust pressure and a current measuring device for measuring input current;
the compressor is a variable frequency compressor, the compressor is further provided with a frequency measuring device for measuring frequency, and the indoor environment applied by the heat pump system is further provided with a fifth temperature measuring device for measuring the side temperature of the indoor environment.
2. The method for controlling an air-supply control device based on an air-source heat pump system according to claim 1, wherein controlling the opening of the air-supply branch electronic expansion valve according to the maximum heating amount criterion and the exhaust superheat degree when the heating amount cannot meet the heat demand in the air-supply mode operation comprises:
s321, if (Δt) n ) i ≤(Δt n ) i-1 The opening of the electronic expansion valve of the air supplementing branch is kept unchanged as the last opening, wherein deltat n Represents the temperature difference delta t of the inlet and outlet air of the indoor heat exchanger n ＝t no -t ni ，(Δt n ) i Represents the temperature difference (delta t) of the inlet and outlet air of the ith indoor heat exchanger n ) i-1 Represents the temperature difference of the inlet air and the outlet air of the indoor heat exchanger of the ith-1 th time;
if (Deltat) n ) i >(Δt n ) i-1 Then according to the formula deltat p ＝t p -t ps Calculating Δt p Jump to step S322;
s322, if Δt p >B, increasing the opening of the electronic expansion valve of the air supplementing branch;
if delta t p B is not more than or equal to the last opening degree of the electronic expansion valve of the air supplementing branch, wherein B represents the lowest set value of the superheat degree of the exhaust;
s323, repeating the steps S321-S322 after the time interval delta tau.
3. The control method of an air source heat pump system-based air make-up control device according to claim 1, wherein said S3 further comprises:
s301, measuring the frequency f of the compressor by using a frequency measuring device, and measuring the indoor environment side temperature t by using a fifth temperature measuring device an According to formula t an -t an-set ＝Δt an Calculating to obtain Deltat an Wherein t is an-set A set value for the indoor environment side temperature;
s302, if Δt an Judging whether the frequency f of the compressor is the maximum value or not, if so, increasing the opening of the electronic expansion valve of the air supplementing branch, and controlling the opening of the electronic expansion valve of the air supplementing branch according to the maximum heating quantity criterion and the superheat degree of the exhaust; if not, repeating the steps S301 and S302 after increasing the frequency of the compressor;
if-2 is less than or equal to deltat an The opening of the electronic expansion valve of the air supplementing branch is controlled according to the COP optimal criterion and the exhaust superheat degree after the opening of the electronic expansion valve of the air supplementing branch is increased to be less than or equal to 2;
if delta t an And (2), reducing the frequency of the compressor, and repeating the steps S301 and S302.
4. The control method of an air-source heat pump system-based air supply control apparatus according to claim 1 or 2, wherein a switching temperature constant a of the air-source heat pump system air supply and non-air supply modes is set to 0 ℃, and a lowest set value B of the exhaust superheat degree is set to 20 ℃.
5. The control method of an air source heat pump system-based air supply control device according to claim 1, wherein an initial opening degree of the air supply branch electronic expansion valve is set to 0.1.
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