CN115183487B - High-speed rail transcritical carbon dioxide heat pump air conditioning system and control method thereof - Google Patents
High-speed rail transcritical carbon dioxide heat pump air conditioning system and control method thereof Download PDFInfo
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- CN115183487B CN115183487B CN202210785086.8A CN202210785086A CN115183487B CN 115183487 B CN115183487 B CN 115183487B CN 202210785086 A CN202210785086 A CN 202210785086A CN 115183487 B CN115183487 B CN 115183487B
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 52
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 32
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 32
- 238000004378 air conditioning Methods 0.000 title claims abstract description 30
- 238000010438 heat treatment Methods 0.000 claims abstract description 31
- 239000003507 refrigerant Substances 0.000 claims abstract description 25
- 238000005057 refrigeration Methods 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 5
- 238000010792 warming Methods 0.000 abstract description 5
- 238000004134 energy conservation Methods 0.000 abstract description 4
- 230000009467 reduction Effects 0.000 abstract description 4
- 230000008859 change Effects 0.000 description 7
- 230000006872 improvement Effects 0.000 description 5
- 238000005265 energy consumption Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000005457 optimization Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005314 correlation function Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
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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
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61D—BODY DETAILS OR KINDS OF RAILWAY VEHICLES
- B61D27/00—Heating, cooling, ventilating, or air-conditioning
- B61D27/0018—Air-conditioning means, i.e. combining at least two of the following ways of treating or supplying air, namely heating, cooling or ventilating
-
- 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
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
-
- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T30/00—Transportation of goods or passengers via railways, e.g. energy recovery or reducing air resistance
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The invention discloses a high-speed rail transcritical carbon dioxide heat pump air conditioning system and a control method thereof, wherein the control method comprises the following steps: acquiring and acquiring the temperature of a carriage, the outdoor environment temperature of a region where a train passes, the fresh air ratio, the carriage load factor, the vehicle running speed, the current system exhaust pressure and the valve opening of a current system electronic expansion valve; selecting the number of compressors to operate; calculating the operating frequency of the compressor; calculating a system optimal exhaust pressure; adjusting the valve opening of the electronic expansion valve to reach the optimal system pressure discharge pressure; wherein carbon dioxide is used as the circulating refrigerant. The invention adopts carbon dioxide as the refrigerant, has low global warming potential GWP and good heating performance, and is beneficial to energy conservation and emission reduction of high-speed rail.
Description
Technical Field
The invention belongs to the technical field of high-speed rail heat pump air conditioner control, and particularly relates to a high-speed rail transcritical carbon dioxide heat pump air conditioner system and a control method thereof.
Background
High iron refrigerants go from traditional HFCs to CO 2 The replacement pace of the natural refrigerant is quickened; wherein, the conventional hydrofluorocarbon HFC refrigerant has high global warming potential GWP and poor low-temperature heating performance, while CO 2 As a natural refrigerant, the natural refrigerant has the advantages of low GWP, good heating performance, incombustibility, non-toxicity, reliability and the like, and is an ideal refrigerant alternative scheme. Due to CO 2 Refrigerant and transcritical air conditioning heat pump system thereof have recently begun to be popularized to rail vehicle application fields, and therefore, it is necessary to propose a new rail vehicle heat pump air conditioning control method suitable for transcritical CO 2 A heat pump air conditioner.
The existing high-speed rail air conditioning system generally adopts a double-system operation mode through the double systemsThe start and stop of the compressor are controlled to realize the adjustment of 0%, 50% and 100% of refrigerating capacity; in addition, since the conventional refrigerant has poor low-temperature heating performance, an electric heater is also required to maintain sufficient heating. The control mode has certain defects, and mainly comprises the following steps: the small number of refrigeration capacity adjustment stages can cause larger energy consumption; the high-speed rail operation region is wide, the external environment is greatly changed, the thermal load of the carriage is greatly changed, a single refrigerating capacity adjusting mode cannot adapt to the change of the thermal load, and the refrigerating capacity is often larger; furthermore, transcritical CO 2 The circulation system often has an optimal exhaust pressure at which the system energy efficiency ratio COP is highest and the system energy consumption is lowest, and therefore it is necessary to control the system to operate at the optimal exhaust pressure and control the valve opening of the electronic expansion valve to achieve the optimal exhaust pressure.
Transcritical CO for other existing vehicles (e.g., passenger cars and coaches) 2 The system-related control method is not applicable to high-speed rails, and is mainly because: in terms of system configuration structure, the high-speed rail air conditioner is generally a double system, and the passenger car are generally single systems; the high-speed rail has high running speed, large geographical span and large running condition change, and the running conditions of the passenger car and the passenger car have small change; in addition, the high-speed railway outdoor fan has a compact structure, so that the heat exchange temperature difference is large, and the air pressure loss is large due to the long indoor air duct. Therefore, a set of high-iron transcritical CO suitable for high-iron transcritical needs to be re-proposed 2 And (5) a control idea of the system.
Disclosure of Invention
The invention aims to provide a high-iron transcritical carbon dioxide heat pump air conditioning system and a control method thereof, which are used for solving one or more technical problems. The invention adopts carbon dioxide as the refrigerant, has low global warming potential GWP and good heating performance, and is beneficial to energy conservation and emission reduction of high-speed rail.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a high-speed rail transcritical carbon dioxide heat pump air conditioning system, which comprises: the two identical units are an indoor fan and a fresh air valve which are commonly used by the two units;
each of the two unitsThe units comprise a compressor, a first electric three-way ball valve, a second electric three-way ball valve, an electronic expansion valve, an in-vehicle heat exchanger, an out-vehicle heat exchanger, a heat regenerator, a gas-liquid separator and an outdoor fan; the outlet of the compressor is communicated with the port b of the first electric three-way ball valve, and the port a of the first electric three-way ball valve is communicated with the port c of the first electric three-way ball valve once through the first channel of the external heat exchanger, the first channel of the heat regenerator, the electronic expansion valve and the first channel of the internal heat exchanger; the inlet of the compressor is communicated with the e-port of the second electric three-way ball valve sequentially through the second channel of the heat regenerator and the gas-liquid separator, the d-port of the second electric three-way ball valve is communicated with the inlet of the first channel of the external heat exchanger, and the f-port of the second electric three-way ball valve is communicated with the outlet of the first channel of the internal heat exchanger; the outdoor fan is arranged on the vehicle exterior heat exchanger; the indoor fan and the fresh air valve are arranged in the vehicle heat exchanger; the circulating refrigerant being CO 2 。
A further improvement of the invention is that the compressor is a variable frequency compressor.
The invention provides a control method of a high-speed rail transcritical carbon dioxide heat pump air conditioning system, which comprises the following steps:
in the refrigeration operation mode, CO 2 The refrigerant flows from the port b to the port a of the first electric three-way valve to the heat exchanger outside the vehicle, and flows from the port f to the port e of the second electric three-way valve to the gas-liquid separator; in the heating operation mode, CO 2 The refrigerant flows from the port b to the port c of the first electric three-way valve to the heat exchanger in the vehicle, and flows from the port d to the port e of the first electric three-way valve to the gas-liquid separator;
obtaining the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh Carriage load factor W pass Vehicle travel speed V S Current system exhaust pressure P n The valve opening OP of the electronic expansion valve of the current system; based on the cabin temperature T i Selecting the number of compressors to operate according to the target compartment temperature; according to carCarriage temperature T i Ambient temperature T o Fresh air ratio R fresh Carriage load factor W pass And vehicle running speed V s Determining a compressor operating frequency; according to the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh Calculating the optimal discharge pressure of the system with the frequency of the compressor; and based on the optimal exhaust pressure of the system, adjusting the valve opening of the electronic expansion valve to achieve the optimal exhaust pressure of the system to realize control.
A further improvement of the control method of the invention is that the control method is based on the cabin temperature T i The step of selecting the number of compressors to operate with the target cabin temperature includes:
in the refrigeration operation mode, the target compartment temperature is set to be T cs ，T c1 Is the upper limit value of the temperature fluctuation of the carriage during refrigeration, T c4 Is the lower limit value of the temperature fluctuation of the carriage during refrigeration, T cs ＝1/2*(T c1 +T c4 ) Several temperature boundary values of the switching control state are respectively T c1 、 T c2 、T c3 、T c4 ，T c1 ＞T c2 ＞T c3 ＞T c4 And |T c1 -T c2 |:|T c2 -T c3 |:|T c3 -T c4 |＝a 1 :a 2 :a 3 ，a 1 ＞a 2 ＞a 3 The method comprises the steps of carrying out a first treatment on the surface of the When the temperature T of the carriage i ＞T c1 When two compressors are started, the frequency is operated in a higher frequency state, T c2 ＜T i ≤T c1 When two compressors are started, the frequency is operated in a relatively medium frequency state, T c3 ＜T i ≤T c2 When two compressors are started, the frequency is operated in a lower frequency state T c4 ＜T i ≤T c3 When a compressor is started, the frequency is operated at a lower frequency state, T i ≤T c4 When the compressor is shut down and up to T i ＞T c1 Starting up the machine;
in the heating operation mode, the target cabin temperature is set to be T hs ，T h1 T is the upper limit value of the temperature fluctuation of the carriage during heating h4 T is the lower limit value of the temperature fluctuation of the carriage during heating hs ＝1/2*(T h1 +T h4 ) Several temperature boundary values of the switching control state are respectively T h1 、 T h2 、T h3 、T h4 ，T h1 ＜T h2 ＜T h3 ＜T h4 And |T h1 -T h2 |:|T h2 -T h3 |:|T h3 -T h4 |＝b 1 :b 2 :b 3 ，b 1 ＞b 2 ＞b 3 When the temperature T of the carriage i ＜T h1 When two compressors are started, the frequency is operated in a higher frequency state, T h1 ≤T i ＜T h2 When two compressors are started, the frequency is operated in a relatively medium frequency state, T h2 ≤T i ＜T h3 When two compressors are started, the frequency is operated in a lower frequency state, T h3 ≤T i ＜T h4 When a compressor is started, the frequency is operated at a lower frequency state, T i ≥T h4 When the compressor is shut down and up to T i ＜T h1 And starting up.
A further improvement of the control method of the invention is that the control method is based on the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh Carriage load factor W pass And vehicle running speed V s The step of determining the operating frequency of the compressor includes:
in the cooling operation mode, the outside environment temperature T is set oc As a parting line, the outside environment temperature T o Above T oc The overall compressor frequency is higher than the vehicle exterior environment temperature T o Below T oc Overall compressor frequency at that time; frequency f cool Controlled according to the following relation:
when T is o ≥T oc At time f cool ＝f1(T o ，T i ，R fresh ，W pass ，V s )；
When T is o ＜T oc At time f cool ＝f2(T o ，T i ，R fresh ，W pass ，V s )；
In the heating operation mode, the outside environment temperature T is set oh As a dividing line, a plurality of dividing lines,outside environment temperature T o Below T oh The overall compressor frequency is higher than the vehicle exterior environment temperature T o Above T oh Overall compressor frequency at that time; frequency f heat Controlled according to the following relation:
when T is o ≤T oh At time f heat ＝f3(T o ，T i ，R fresh ，W pass ，V s )；
When T is o ＞T oh At time f heat ＝f4(T o ，T i ，R fresh ，W pass ，V s )。
A further improvement of the control method of the invention is that the control method is based on the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh The step of calculating the system optimum discharge pressure with the compressor frequency includes:
according to the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh Optimum discharge pressure p with compressor frequency calculation system op The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the optimal exhaust pressure of refrigeration is p op，cool Heating optimum exhaust pressure p op，heat The optimal exhaust pressure is calculated according to the following correlation: p is p op，cool ＝fc(T o ，T i ，R fresh ，f cool )；p op，heat ＝fh(T o ，T i ，R fresh ，f cool )。
A further improvement of the control method of the present invention is that if the calculated system optimum exhaust pressure value is greater than 13MPa, the system optimum exhaust pressure is set to 13MPa.
The control method of the invention is further improved in that the step of adjusting the valve opening of the electronic expansion valve to achieve the control of the optimal system discharge pressure based on the optimal system discharge pressure comprises the following steps:
monitoring system discharge pressure value p n If the pressure is different from the set pressure value p op，cool Or p op，heat The absolute value is smaller than 0.05MPa, the valve opening of the electronic expansion valve is unchanged, and if the absolute value is larger than the set discharge pressure value by 0.05MPa, the electronic expansion valve is reducedThe valve opening of the expansion valve is increased when the valve opening is smaller than the set discharge pressure value by 0.05MPa, and the pressure difference is converted into a valve opening change amount Δop=c×|p when the electronic expansion valve is adjusted n -p op And C is a proportionality coefficient.
Compared with the prior art, the invention has the following beneficial effects:
in the present invention, there is provided a method for applying to transcritical CO 2 A method for controlling the frequency of compressor and optimal exhaust pressure of high-speed rail heat pump air conditioner. Compared with the traditional hydrofluorocarbon HFC refrigerant carbon dioxide refrigerant, the refrigerant is environment-friendly and clean, has low global warming potential value GWP and good heating performance, and is beneficial to energy conservation and emission reduction of high-speed rail.
The control method can control the running number of the compressors and realize energy multistage adjustment; the running frequency of the compressor can be selected, so that energy optimization and distribution are realized, and the comfort level of the carriage is ensured; by searching the optimal exhaust pressure of the system and adjusting the opening of the expansion valve, the energy efficiency of the system is saved.
In the invention, the temperature range of the carriage is divided into a plurality of cells and controlled in multiple stages, each stage corresponds to different refrigerating capacity ranges, the temperature fluctuation range is reduced, and the compressor is protected from frequent start and stop.
In the invention, the correlation type compressor frequency is provided for different external environment temperatures and carriage temperatures.
In the present invention, trans-critical CO 2 The system has the lowest energy consumption under the optimal exhaust pressure, and the correlation degree between the optimal exhaust pressure and the ambient temperature, the fresh air ratio and the carriage temperature is higher, so that the correlation type of the optimal exhaust pressure is also provided, and a control method of the valve opening of the electronic expansion valve is also provided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description of the embodiments or the drawings used in the description of the prior art will make a brief description; it will be apparent to those of ordinary skill in the art that the drawings in the following description are of some embodiments of the invention and that other drawings may be derived from them without undue effort.
FIG. 1 is a schematic diagram of a high-speed rail transcritical carbon dioxide heat pump air conditioning system according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a control method of a high-speed rail transcritical carbon dioxide heat pump air conditioning system according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a determining flow of the number of compressors in a transcritical carbon dioxide high-speed rail heat pump air conditioning system in an embodiment of the present invention;
FIG. 4 is a schematic diagram of a determined flow of frequencies of a transcritical carbon dioxide high-iron heat pump air conditioning system in accordance with an embodiment of the present invention;
FIG. 5 is a schematic flow chart of an optimal exhaust pressure control method of a transcritical carbon dioxide high-speed rail heat pump air conditioning system in an embodiment of the invention;
in the figure, 1, a compressor; 2. the first electric three-way ball valve; 3. the second electric three-way ball valve; 4. an electronic expansion valve; 5. an in-vehicle heat exchanger; 6. an off-vehicle heat exchanger; 7. a regenerator; 8. a gas-liquid separator; 9. an outdoor fan; 10. an indoor fan; 11. a fresh air valve; 12. an indoor heat exchanger; 13. the rest parts.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the attached drawing figures:
referring to fig. 1, a high-speed rail transcritical carbon dioxide heat pump air conditioning system according to an embodiment of the present invention includes two units having identical components; each unit comprises a compressor 1, a first electric three-way ball valve 2, a second electric three-way ball valve 3, an electronic expansion valve 4, an in-vehicle heat exchanger 5, an out-of-vehicle heat exchanger 6, a regenerator 7, a gas-liquid separator 8 and an outdoor fan 9, wherein the two units commonly use two indoor fans 10 and a fresh air valve 11, and for simplicity of representation, the two units are illustratively expressed as comprising an indoor heat exchanger 12 and the rest of components 13 except the indoor heat exchanger 12.
In the embodiment of the invention, the outlet of the compressor 1 is connected with the b port of the first electric three-way ball valve 2, the a port of the first electric three-way ball valve 2 is connected with the inlet of the external heat exchanger 6, the c port is connected with the outlet of the internal heat exchanger 5, the outlet of the external heat exchanger 6 is connected with the first inlet of the heat regenerator 7, the first outlet of the heat regenerator 7 is connected with the inlet of the electronic expansion valve 4, the outlet of the electronic expansion valve 4 is connected with the inlet of the internal heat exchanger 5, the outlet of the internal heat exchanger 5 is connected with the f port of the second electric three-way ball valve 3, the e port of the second electric three-way ball valve 3 is connected with the inlet of the gas-liquid separator 8, the d port is connected with the inlet of the external heat exchanger 6, the outlet of the gas-liquid separator 8 is connected with the second inlet of the heat regenerator 7, and the second outlet of the heat regenerator 7 is connected with the inlet of the variable frequency compressor 1.
The main working modes of the system of the embodiment of the invention are a refrigerating mode and a heating mode, and the system realizes the conversion of the refrigerating mode and the heating mode through two electric three-way valves; the refrigeration mode comprises the steps that under the refrigeration mode, refrigerant carbon dioxide flows from a port b to a port a of a first electric three-way valve to reach an external heat exchanger of the vehicle, and flows from a port f to a port e of a second electric three-way valve to reach a gas-liquid separator; and under the heating mode, the carbon dioxide of the refrigerant flows from the port b to the port c of the first electric three-way valve to the heat exchanger in the vehicle, and flows from the port d to the port e of the first electric three-way valve to the gas-liquid separator.
The embodiment of the invention is exemplarily preferred that the system compressor is a variable frequency compressor, so that the system can realize energy adjustment of refrigerating capacity and heating capacity, and the two units adjust frequencies by using the same set of compressor control method, namely, the compressor frequency is kept the same when the two units work simultaneously.
Referring to fig. 2, a control method of a high-speed rail transcritical carbon dioxide heat pump air conditioning system according to an embodiment of the present invention includes the steps of:
s1, collecting the temperature T of a carriage i Collecting the outdoor environment temperature T of the area where the train passes o Collecting the opening degree of a fresh air valve, namely collecting the fresh air ratio R fresh The method comprises the steps of carrying out a first treatment on the surface of the Collecting carriage load factor W pass Collecting the running speed V of the vehicle S Collecting the current system exhaust pressure P n Collecting the valve opening OP of the electronic expansion valve of the current system;
s2, selecting the number of compressors to operate;
s3, calculating the operation frequency of the compressor;
s4, calculating the optimal exhaust pressure of the system; adjusting the valve opening of the electronic expansion valve to reach the optimal system pressure discharge pressure;
specifically, the steps are dynamically performed in real time to realize dynamic adjustment of the system.
Referring to fig. 3, a method for selecting the number of compressors in a high-speed rail transcritical carbon dioxide heat pump air conditioning system according to an embodiment of the present invention specifically includes the following steps:
in the refrigeration operation mode, the target compartment temperature is set to be T cs ，T c1 Is the upper limit value of the temperature fluctuation of the carriage during refrigeration, T c4 Is the lower limit value of the temperature fluctuation of the carriage during refrigeration, T cs ＝1/2*(T c1 +T c4 ) Several temperature boundary values of the switching control state are respectively T c1 、 T c2 、T c3 、T c4 ，T c1 ＞T c2 ＞T c3 ＞T c4 And |T c1 -T c2 |:|T c2 -T c3 |:|T c3 -T c4 |＝a 1 :a 2 :a 3 ，a 1 ＞a 2 ＞a 3 When the temperature T of the carriage i ＞T c1 When two compressors are started, the frequency is operated in a higher frequency state, T c2 ＜T i ≤T c1 When two compressors are started, the frequency is operated in a relatively medium frequency state, T c3 ＜T i ≤T c2 When two compressors are started, the frequency is operated in a lower frequency state T c4 ＜T i ≤T c3 When a compressor is started, the frequency is operated at a lower frequency state, T i ≤T c4 When the compressor is shut down until T i ＞T c1 Starting up the machine;
in the heating operation mode, the target cabin temperature is set to be T hs ，T h1 T is the upper limit value of the temperature fluctuation of the carriage during heating h4 T is the lower limit value of the temperature fluctuation of the carriage during heating hs ＝1/2*(T h1 +T h4 ) Several temperature boundary values of the switching control state are respectively T h1 、 T h2 、T h3 、T h4 ，T h1 ＜T h2 ＜T h3 ＜T h4 And |T h1 -T h2 |:|T h2 -T h3 |:|T h3 -T h4 |＝b 1 :b 2 :b 3 ，b 1 ＞b 2 ＞b 3 When the temperature T of the carriage i ＜T h1 When two compressors are started, the frequency is operated in a higher frequency state, T h1 ≤T i ＜T h2 When two compressors are started, the frequency is operated in a relatively medium frequency state, T h2 ≤T i ＜T h3 When two compressors are started, the frequency is operated in a lower frequency state, T h3 ≤T i ＜T h4 When a compressor is started, the frequency is operated at a lower frequency state, T i ≥T h4 When the compressor is shut down until T i ＜T h1 And starting up.
An exemplary embodiment of the present invention is described,a 1 、a 2 、a 3 and b 1 、b 2 、b 3 With cabin temperature T i With the outdoor ambient temperature T o The correlation degree is high, and a is changed under certain environment temperature and set carriage temperature 1 :a 2 And a 2 :a 3 Through experiments or simulation, taking the small number of times of starting and stopping the compressor in unit time and the small temperature fluctuation amplitude as optimization targets, and taking corresponding a if the minimum number of times of starting and stopping the compressor in unit time and the small temperature fluctuation amplitude are smaller 1 :a 2 And a 2 :a 3 In addition, a different ambient temperatures correspond to the cabin temperature 1 :a 2 And a 2 :a 3 Different values, a 1 :a 2 ＝f1(T o ，T i )，a 2 :a 3 ＝f2(T o ，T i ) The corresponding correlation function relationship can be obtained through limited experiments or simulation.
Referring to fig. 4, a method for calculating an operating frequency of a compressor of a high-speed rail transcritical carbon dioxide heat pump air conditioning system according to an embodiment of the present invention specifically includes the following steps:
the performance of the outdoor environment temperature increasing system is reduced in the refrigerating operation mode, and the outdoor environment temperature T is used for meeting the refrigerating capacity oc As a parting line, ambient temperature T o Above T oc When the overall compressor frequency is higher than ambient temperature T o Below T oc Overall compressor frequency at that time, and thus cooling mode frequency f cool Controlled according to the following relation:
when T is o ≥T oc At time f cool ＝f1(T o ，T i ，R fresh ，W pass ，V s )；
When T is o ＜T oc At time f cool ＝f2(T o ，T i ，R fresh ，W pass ，V s )；
In the heating operation mode, the performance of the outdoor environment temperature reducing system is reduced, and the environment temperature T is set to meet the heating quantity oh As a parting line, the ambient temperature is lower than T oh Overall compressor at the timeThe frequency is higher than the ambient temperature and higher than T oh Overall compressor frequency at that time, therefore heating operation mode frequency f heat Controlled according to the following relation:
when T is o ≤T oh At time f heat ＝f3(T o ，T i ，R fresh ，W pass ，V s )；
When T is o ＞T oh At time f heat ＝f4(T o ，T i ，R fresh ，W pass ，V s )；
The specific control relation is obtained through limited experiments according to the functions according to the quantitative relation.
Principle explanatory, cabin load and ambient temperature T o The load directly influenced by the ambient temperature comprises fresh air load and enclosure structure load, so the compressor frequency is not only related to the temperature T of a carriage i In the related art, different compressor frequencies should be adopted at different environmental temperatures, and the fresh air load and personnel load occupy relatively large amounts, so the fresh air ratio R fresh Carriage load factor W pass Also has a great influence on the load, and finally the running speed V of the vehicle s The heat transfer coefficient of the vehicle body is influenced, and the load is also greatly influenced. In conclusion, the operation frequency of the compressor is determined according to the temperature of the compartment, the temperature of the outside environment of the vehicle, the fresh air ratio, the passenger carrying rate of the compartment and the running speed of the vehicle.
Referring to fig. 5, the method for calculating the optimal exhaust pressure of the system according to the embodiment of the invention specifically includes the following steps: calculating the optimal exhaust pressure p of the system according to the temperature of the carriage, the temperature of the outside environment of the vehicle and the fresh air ratio and the frequency of the compressor op The optimal discharge pressure of refrigeration is p op，cool Heating optimum exhaust pressure p op，heat The optimal exhaust pressure is calculated according to the following correlation:
p op，cool ＝fc(T o ，T i ，R fresh ，f cool )；
p op，heat ＝fh(T o ，T i ，R fresh ，f cool )；
the specific control relation is obtained through limited experiments according to the functions according to the quantitative relation;
in view of system safety, the system exhaust pressure cannot be greater than 13MPa, and if the calculated optimum exhaust pressure value is greater than 13MPa, the exhaust pressure will be set to 13MPa.
In the embodiment of the invention, the method for adjusting the opening of the electronic expansion valve comprises the following steps: monitoring system discharge pressure value p n If the pressure is different from the set pressure value p op，cool Or p op，heat The valve opening of the electronic expansion valve is unchanged if the absolute value is smaller than 0.05MPa, the valve opening of the electronic expansion valve is reduced if the absolute value is 0.05MPa larger than the set discharge pressure value, the valve opening of the electronic expansion valve is increased if the absolute value is 0.05MPa smaller than the set discharge pressure value, and the differential pressure is converted into a valve opening variation Δop=c|p when the electronic expansion valve is adjusted n -p op And C is a proportionality coefficient, when the difference between the current exhaust pressure and the optimal exhaust pressure is larger, the valve opening change amount of the electronic expansion valve is larger, and when the difference between the current exhaust pressure and the optimal exhaust pressure is smaller, the valve opening change amount of the electronic expansion valve is smaller.
In summary, the embodiment of the invention discloses a high-speed rail transcritical carbon dioxide heat pump air conditioning system and a control method thereof, wherein a unit comprises 2 sets of independent heat pump air conditioning units, each unit comprises a variable-frequency compressor, an electric three-way ball valve, an electronic expansion valve, an in-vehicle heat exchanger, an out-vehicle heat exchanger, a heat regenerator and a gas-liquid separator, and the unit further comprises an outdoor fan, an indoor fan and a fresh air valve; the invention divides the temperature range of the carriage into a plurality of intervals and multi-stage control, each stage corresponds to different refrigerating capacity ranges, reduces the temperature fluctuation range and protects the compressor; meanwhile, aiming at the influence parameters such as different external environment temperatures, carriage temperatures and the like, the correlation of the compressor frequency is provided, the normal operation of the high-speed rail air-conditioning heat pump in a wide working condition range is ensured, meanwhile, the correlation of the optimal exhaust pressure of the high-speed rail air-conditioning system is provided, signals such as the environment temperature, the carriage temperature, the fresh air ratio and the like are collected, the optimal exhaust pressure is obtained through calculation, so that the optimal performance of a transcritical carbon dioxide system is achieved, and the control method of the electronic expansion valve is provided. The embodiment of the invention provides a high-iron transcritical carbon dioxide heat pumpThe control method of the air conditioning system is used for controlling the number of compressors to operate, realizing energy multistage adjustment, selecting the operating frequency of the compressors, realizing energy optimization and distribution, guaranteeing the comfort level of a carriage, searching the optimal exhaust pressure of the system, adjusting the opening of an expansion valve and saving the energy efficiency of the system. Compared with the traditional hydrofluorocarbon HFC refrigerant carbon dioxide refrigerant, the refrigerant is environment-friendly and clean, has low global warming potential value GWP and good heating performance, and is beneficial to energy conservation and emission reduction of high-speed rail. The energy adjusting range of the existing high-speed rail air conditioning system in the control mode is only 50% and 100%, the refrigerating capacity is large, and meanwhile, the single refrigerating capacity adjusting mode cannot adapt to the change of the thermal load. Second, the present invention proposes a method for transcritical CO 2 High-speed rail heat pump air conditioner control method and transcritical CO 2 The circulation system often has the optimal exhaust pressure, the energy efficiency ratio COP of the system is highest under the optimal exhaust pressure, the energy consumption of the system is lowest, and the correlation degree of the optimal exhaust pressure and factors such as the ambient temperature, the fresh air ratio, the carriage temperature and the like is higher for the system, so the invention provides the correlation type and the adjusting method of the optimal exhaust pressure of the system.
Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (5)
1. A control method of a high-iron transcritical carbon dioxide heat pump air conditioning system is characterized in that,
the high-speed rail transcritical carbon dioxide heat pump air conditioning system comprises: an indoor fan (10) and a fresh air valve (11) which are used by the two identical units together;
of the two unitsEach unit comprises a compressor (1), a first electric three-way ball valve (2), a second electric three-way ball valve (3), an electronic expansion valve (4), an in-vehicle heat exchanger (5), an out-of-vehicle heat exchanger (6), a heat regenerator (7), a gas-liquid separator (8) and an outdoor fan (9); the outlet of the compressor (1) is communicated with the b port of the first electric three-way ball valve (2), and the a port of the first electric three-way ball valve (2) is communicated with the c port of the first electric three-way ball valve (2) through the first channel of the external heat exchanger (6), the first channel of the heat regenerator (7), the electronic expansion valve (4) and the first channel of the internal heat exchanger (5) at one time; the inlet of the compressor (1) is communicated with the e port of the second electric three-way ball valve (3) sequentially through the second channel of the heat regenerator (7) and the gas-liquid separator (8), the d port of the second electric three-way ball valve (3) is communicated with the inlet of the first channel of the heat exchanger (6) outside the vehicle, and the f port of the second electric three-way ball valve (3) is communicated with the outlet of the first channel of the heat exchanger (5) inside the vehicle; the outdoor heat exchanger (6) is provided with the outdoor fan (9); the in-car heat exchanger (5) is provided with the indoor fan (10) and a fresh air valve (11); the circulating refrigerant being CO 2 ；
The control method comprises the following steps:
in the refrigeration operation mode, CO 2 The refrigerant flows from the port b to the port a of the first electric three-way valve to the heat exchanger outside the vehicle, and flows from the port f to the port e of the second electric three-way valve to the gas-liquid separator; in the heating operation mode, CO 2 The refrigerant flows from the port b to the port c of the first electric three-way valve to the heat exchanger in the vehicle, and flows from the port d to the port e of the first electric three-way valve to the gas-liquid separator;
obtaining the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh Carriage load factor W pass Vehicle travel speed V S Current system exhaust pressure P n The valve opening OP of the electronic expansion valve of the current system; based on the cabin temperature T i Selecting the number of compressors to operate according to the target compartment temperature; according to the temperature T of the carriage i Ambient temperature T o Fresh air ratio R fresh Vehicle and its control methodCarriage load factor W pass And vehicle running speed V s Determining a compressor operating frequency; according to the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh Calculating the optimal discharge pressure of the system with the frequency of the compressor; based on the optimal exhaust pressure of the system, adjusting the valve opening of the electronic expansion valve to achieve the optimal exhaust pressure of the system to realize control;
said temperature T of the carriage i The step of selecting the number of compressors to operate with the target cabin temperature includes:
in the refrigeration operation mode, the target compartment temperature is set to be T cs ，T c1 Is the upper limit value of the temperature fluctuation of the carriage during refrigeration, T c4 Is the lower limit value of the temperature fluctuation of the carriage during refrigeration, T cs ＝1/2*(T c1 +T c4 ) Several temperature boundary values of the switching control state are respectively T c1 、T c2 、T c3 、T c4 ，T c1 ＞T c2 ＞T c3 ＞T c4 And |T c1 -T c2 |:|T c2 -T c3 |:|T c3 -T c4 |＝a 1 :a 2 :a 3 ，a 1 ＞a 2 ＞a 3 The method comprises the steps of carrying out a first treatment on the surface of the When the temperature T of the carriage i ＞T c1 When two compressors are started, the frequency is operated in a higher frequency state, T c2 ＜T i ≤T c1 When two compressors are started, the frequency is operated in a relatively medium frequency state, T c3 ＜T i ≤T c2 When two compressors are started, the frequency is operated in a lower frequency state T c4 ＜T i ≤T c3 When a compressor is started, the frequency is operated at a lower frequency state, T i ≤T c4 When the compressor is shut down and up to T i ＞T c1 Starting up the machine;
in the heating operation mode, the target cabin temperature is set to be T hs ，T h1 T is the upper limit value of the temperature fluctuation of the carriage during heating h4 T is the lower limit value of the temperature fluctuation of the carriage during heating hs ＝1/2*(T h1 +T h4 ) Several temperature boundary values of the switching control state are respectively T h1 、T h2 、T h3 、T h4 ，T h1 ＜T h2 ＜T h3 ＜T h4 And |T h1 -T h2 |:|T h2 -T h3 |:|T h3 -T h4 |＝b 1 :b 2 :b 3 ，b 1 ＞b 2 ＞b 3 When the temperature T of the carriage i ＜T h1 When two compressors are started, the frequency is operated in a higher frequency state, T h1 ≤T i ＜T h2 When two compressors are started, the frequency is operated in a relatively medium frequency state, T h2 ≤T i ＜T h3 When two compressors are started, the frequency is operated in a lower frequency state, T h3 ≤T i ＜T h4 When a compressor is started, the frequency is operated at a lower frequency state, T i ≥T h4 When the compressor is shut down and up to T i ＜T h1 And starting up.
2. The control method of the high-speed rail transcritical carbon dioxide heat pump air conditioning system according to claim 1, wherein the control method is based on a cabin temperature T i Outside environment temperature T o Fresh air ratio R fresh Carriage load factor W pass And vehicle running speed V s The step of determining the operating frequency of the compressor includes:
in the cooling operation mode, the outside environment temperature T is set oc As a parting line, the outside environment temperature T o Above T oc The overall compressor frequency is higher than the vehicle exterior environment temperature T o Below T oc Overall compressor frequency at that time; frequency f cool Controlled according to the following relation:
when T is o ≥T oc At time f cool ＝f1(T o ，T i ，R fresh ，W pass ，V s )；
When T is o ＜T oc At time f cool ＝f2(T o ，T i ，R fresh ，W pass ，V s )；
In the heating operation mode, the outside environment temperature T is set oh As a parting line, the outside environment temperature T o Below T oh The overall compressor frequency is higher than the vehicle exterior environment temperature T o Above T oh Overall compressor frequency at that time; frequency f heat Controlled according to the following relation:
when T is o ≤T oh At time f heat ＝f3(T o ，T i ，R fresh ，W pass ，V s )；
When T is o ＞T oh At time f heat ＝f4(T o ，T i ，R fresh ，W pass ，V s )。
3. The control method of the high-speed rail transcritical carbon dioxide heat pump air conditioning system according to claim 2, wherein the control method is based on a cabin temperature T i Outside environment temperature T o Fresh air ratio R fresh The step of calculating the system optimum discharge pressure with the compressor frequency includes:
according to the temperature T of the carriage i Outside environment temperature T o Fresh air ratio R fresh Optimum discharge pressure p with compressor frequency calculation system op The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the optimal exhaust pressure of refrigeration is p op Cool, heating optimum exhaust pressure p op，heat The optimal exhaust pressure is calculated according to the following correlation: p is p op，cool ＝fc(T o ，T i ，R fresh ，f cool )；p op，heat ＝fh(T o ，T i ，R fresh ，f cool )。
4. A control method of a high-iron transcritical carbon dioxide heat pump air conditioning system according to claim 3, wherein if the calculated system optimum discharge pressure value is greater than 13MPa, the system optimum discharge pressure is set to 13MPa.
5. A control method of a high-speed rail transcritical carbon dioxide heat pump air conditioning system according to claim 3, wherein the step of adjusting the valve opening of the electronic expansion valve to achieve the system optimal discharge pressure based on the system optimal discharge pressure comprises:
monitoring system discharge pressure value p n If the pressure is different from the set pressure value p op，cool Or p op，heat The valve opening of the electronic expansion valve is unchanged if the absolute value is smaller than 0.05MPa, the valve opening of the electronic expansion valve is reduced if the absolute value is 0.05MPa larger than the set discharge pressure value, the valve opening of the electronic expansion valve is increased if the absolute value is 0.05MPa smaller than the set discharge pressure value, and the differential pressure is converted into a valve opening variation Δop=c|p when the electronic expansion valve is adjusted n -p op And C is a proportionality coefficient.
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