CN112325454A - CO for medium and high speed rail vehicle2Refrigerant air conditioning unit and method - Google Patents
CO for medium and high speed rail vehicle2Refrigerant air conditioning unit and method Download PDFInfo
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- CN112325454A CN112325454A CN202011086797.3A CN202011086797A CN112325454A CN 112325454 A CN112325454 A CN 112325454A CN 202011086797 A CN202011086797 A CN 202011086797A CN 112325454 A CN112325454 A CN 112325454A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61D—BODY DETAILS OR KINDS OF RAILWAY VEHICLES
- B61D27/00—Heating, cooling, ventilating, or air-conditioning
- B61D27/0072—Means for cooling only
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F11/84—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- 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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- 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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Abstract
The invention discloses CO for a medium-high speed rail vehicle2Refrigerant air conditioning unit and method, the method includes: calculating the outlet state and the flow of the compressor based on the outlet pressure of the evaporator with the preset high energy efficiency ratio; calculating the inlet state of the evaporator based on the outlet pressure of the evaporator with the preset high energy efficiency ratio; calculating the inlet state of the air cooler based on the outlet pressure of the evaporator with the preset high energy efficiency ratio; according to the outlet state of the compressor, the flow rate of the compressor, the inlet state of the evaporator and the inlet state of the air cooler, which are obtained through calculation, for CO2Of refrigerating systemsPerforming fitting calculation on the operation parameters; and determining parameters of components of the high energy efficiency ratio according to the fitting calculation result, wherein the components comprise a compressor, an evaporator and an air cooler. The invention improves CO2Energy efficiency ratio of refrigeration system and reduced CO2The air conditioning unit has low system cost and can be widely applied to the technical field of air conditioning systems.
Description
Technical Field
The invention relates to the field of air conditioners for upper rail vehicles, in particular to CO for medium and high speed rail vehicles2Refrigerant air conditioning unit and method.
Background
The rail vehicle air conditioner is greatly different from common commercial and civil air conditioners, the rail vehicle air conditioner is a special air conditioning system specially used for railway passenger trains, and the requirements on vibration performance, high-temperature performance and reliability of an air conditioning unit are high.
HCFCs refrigerants such as R134a, R407C, R410A, R32 and the like applied in the refrigeration industry at present are all unnatural working media, belong to transition refrigerants and are subject to comprehensive forbidding due to high greenhouse effect index. At present, the ordinary high-speed large railway air conditioning units at home and abroad mainly adopt R134a and R407C transition type environment-friendly refrigerants.
In addition, because the natural working medium refrigerants of R717 and R290 have high risk factors such as pungent smell, toxicity, flammability, easiness in explosion and the like, and the requirements on the safety and reliability of the vehicle air conditioner are extremely high, the R717 and the R290 are not suitable for the vehicle air conditioner.
As CFC and HCFC refrigerant is gradually forbidden in the future, the development of environment-friendly and energy-saving technology becomes the main direction for determining the development of rail vehicle air conditioners in the future. When HCFCs refrigerant is completely forbidden, natural working medium refrigerant closest to train air conditioner includes air and CO2. Air conditioners using air as a refrigerant have been used in Germany ICE trains, but since turbines like aircraft air conditioners are required, the structure is complicated, the cost is high, and the energy efficiency ratio is highAnd therefore, the device cannot be popularized and applied to other rail vehicles.
The air conditioner of the railway vehicle is arranged on the roof, the condensation effect of the air conditioning unit is related to the running speed of the train, the higher the running speed is, the more the condensation effect is attenuated, and CO is2The refrigerating performance of the refrigerant at high temperature is poorer than that of the prior transition type environment-friendly refrigerant rail air-conditioning unit mainly adopting R134a and R407C at home and abroad.
The higher the speed per hour of the railway vehicle is, the higher the energy consumption is, in order to effectively reduce the energy consumption, the weight of the vehicle body needs to be reduced, the weight of the transition type environment-friendly refrigerant air conditioning unit with the speed per hour being less than 350 kilometers is about 980Kg, and the weight of the air conditioning unit with the speed per hour being more than 350 kilometers is required to be reduced by 10%.
Disclosure of Invention
To solve the above technical problems, the present invention aims to: provides CO for medium and high speed rail vehicle with high energy efficiency ratio, light weight and adaptation to rail vehicle with speed per hour of more than 350 km2Refrigerant air conditioning unit and method.
The two aspects of the invention adopt the technical scheme that:
the technical scheme adopted by the other aspect of the invention is as follows:
CO for medium and high speed rail vehicle2Refrigerant air conditioning unit, comprising the following aspects:
the air conditioning unit adopts natural environment-friendly working medium CO2As a refrigerant, the refrigerant can effectively replace CFC and HCFC refrigerant type air conditioning units;
the air conditioning unit is suitable for the rail vehicle with the speed per hour of more than 350 kilometers;
CO for medium and high speed rail vehicle2The energy efficiency ratio of the refrigerant air-conditioning unit is equivalent to that of the conventional CFC and HCFCs refrigerant air-conditioning unit, and the energy efficiency ratio can reach more than 2.0;
CO2the highest operating pressure of the refrigerant air conditioning unit is 140bar, which is about 4 times of the operating pressure of 30bar of the prior CFC and HCFCs refrigerant air conditioning units, and the refrigerant air conditioning unit belongs to an ultrahigh pressure type air conditioning unit;
CO2the maximum operating environment temperature of the air conditioning unit can reach 50 ℃, and the air conditioning unit belongs to a high-temperature air conditioning unit;
CO2the air conditioning unit adopts a lightweight design technology.
CO for medium and high speed rail vehicle2A method of refrigerant air conditioning units comprising the steps of:
calculating the outlet state and the flow of the compressor based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
calculating the inlet state of the evaporator based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
calculating the inlet state of the air cooler based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
according to the outlet state of the compressor, the flow rate of the compressor, the inlet state of the evaporator and the inlet state of the air cooler, which are obtained through calculation, for CO2Performing fitting calculation on the operating parameters of the refrigeration system;
and determining parameters of components of the high energy efficiency ratio according to the fitting calculation result, wherein the components comprise a compressor, an evaporator and an air cooler.
Further, the method also comprises the following steps:
designing the flow direction of the air cooler into a cross S shape, and increasing the cooling speed of a critical zone of the air cooler through a countercurrent design;
controlling the flow rate of the air cooler through an electronic expansion valve;
dynamically adjusting the installation angle of the air cooler according to the structure of the air conditioning unit;
performing simulation calculation on the relationship between the fin pitch and the heat exchange amount of the air cooler;
combining CO according to the result of simulation calculation2And determining the fin spacing of the air cooler according to the operation parameters of the refrigerating system.
Further, the step of controlling the flow rate of the air cooler by the electronic expansion valve includes the steps of:
acquiring simulation test data of the air cooler under different working conditions, wherein the simulation test data comprises outlet pressure data, temperature data, refrigerating capacity data and energy efficiency data;
fitting calculation is carried out on the simulation test data to obtain an opening control formula of the electronic expansion valve;
the opening degree control formula of the electronic expansion valve is as follows: k is T1 a + T2B + C, where K is the electronic expansion valve opening; t1 represents the air cooler outlet temperature; a represents the outlet temperature coefficient of the air cooler; t2 represents evaporator outlet temperature; b represents the evaporator outlet temperature coefficient; c represents an opening correction system;
and after the opening degree of the electronic expansion valve is calculated according to an opening degree control formula of the electronic expansion valve, the flow of the air cooler is controlled through the opening degree of the electronic expansion valve.
Further, the method also comprises the following steps:
performing simulation calculation on a loop between the air cooler and the evaporator, and optimizing the loop between the air cooler and the evaporator according to a simulation calculation result;
calculating a first parameter of a heat exchange tube of the evaporator based on different specifications of tube diameters;
calculating a second parameter of the heat exchange tube of the air cooler based on different specifications of tube diameters;
according to the calculation result of the first parameter and the calculation result of the second parameter, combining CO2The structure of the refrigeration system determines the pipe diameter of the heat exchange pipe;
the circuit between the air cooler and the evaporator is optimized according to the determined heat exchange pipe.
Further, the method also comprises the following steps:
CO control by gas-liquid separator2Suction pressure of the refrigeration system;
the lubricating oil is separated from the refrigerant by the heater.
Further, the method also comprises the following steps:
carrying out real-time first monitoring on the working pressure of the compressor through a first high-voltage switch;
according to the first monitoring result and the pressure measurement value of the high-pressure sensor, the CO is measured2The refrigerating system carries out load adjustment;
carrying out real-time second monitoring on the working pressure of the compressor through a second high-voltage switch;
based on the result of the second monitoring and the pressure measurement of the high pressure sensor, for CO2The refrigeration system is controlled to be shut down;
carrying out real-time third monitoring on the working pressure of the compressor through a low-voltage switch;
according to the result of the third monitoring, for CO2The refrigeration system is shut down.
Further, the method also comprises the following steps:
by CO2Concentration detector for CO2CO in refrigeration system2Carrying out real-time fourth monitoring on the concentration;
according to the result of the fourth monitoring, for CO2The refrigeration system is shut down.
Further, the method also comprises the following steps:
calculating the pipe diameter thickness and the blasting pressure value based on a preset working pressure coefficient;
according to the calculated pipe diameter thickness and the explosion pressure value, for CO2The pipelines and refrigeration components of the refrigeration system are controlled for burst prevention.
The technical scheme adopted by the other aspect of the invention is as follows:
CO for medium and high speed rail vehicle2Refrigerant air conditioning unit comprising:
the first calculation module is used for calculating the outlet state and the flow of the compressor according to the outlet pressure of the evaporator based on the high energy efficiency ratio;
the second calculation module is used for calculating the inlet state of the evaporator according to the outlet pressure of the evaporator based on the high energy efficiency ratio;
a third calculation module for calculating an inlet state of the air cooler based on the evaporator outlet pressure of the energy-efficient ratio;
a fitting calculation module for fitting CO according to the outlet state of the compressor, the flow rate of the compressor, the inlet state of the evaporator and the inlet state of the air cooler2Performing fitting calculation on the operating parameters of the refrigeration system;
and the determining module is used for determining the parameters of the components with the high energy efficiency ratio according to the result of the fitting calculation, wherein the components comprise a compressor, an evaporator and an air cooler.
The invention has the beneficial effects that: the invention adopts a backward-thrust simulation calculation method, firstly presets the outlet pressure of the evaporator with high energy efficiency ratio, then respectively calculates the outlet state of the compressor, the flow of the compressor, the inlet state of the evaporator and the inlet state of the air cooler, and then carries out the calculation on the CO2Fitting calculation is carried out on the operation parameters of the refrigerating system, and finally the component parameters with high energy efficiency ratio are determined, so that the energy efficiency ratio of the refrigerating system is improved; in addition, the present invention employs CO2Compared with the existing air refrigerating system, the refrigerating system has the advantage that the system cost is greatly reduced.
Drawings
FIG. 1 is a flow chart of the steps performed in the present invention.
Detailed Description
The invention will be further explained and explained with reference to the drawings and specific embodiments. The step numbers in the implementation of the present invention are provided only for convenience of illustration, the sequence between the steps is not limited at all, and the execution sequence of each step in the implementation can be adapted according to the understanding of those skilled in the art.
Referring to FIG. 1, an embodiment of the present invention provides a CO for medium and high speed rail vehicles2A method of refrigerant air conditioning units comprising the steps of:
calculating the outlet state and the flow of the compressor based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
calculating the inlet state of the evaporator based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
calculating the inlet state of the air cooler based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
according to the outlet state of the compressor, the flow rate of the compressor, the inlet state of the evaporator and the inlet state of the air cooler, which are obtained through calculation, for CO2Performing fitting calculation on the operating parameters of the refrigeration system;
and determining parameters of components of the high energy efficiency ratio according to the fitting calculation result, wherein the components comprise a compressor, an evaporator and an air cooler.
Further as a preferred embodiment, the method further comprises the following steps:
designing the flow direction of the air cooler into a cross S shape, and increasing the cooling speed of a critical zone of the air cooler through a countercurrent design;
controlling the flow rate of the air cooler through an electronic expansion valve;
dynamically adjusting the installation angle of the air cooler according to the structure of the air conditioning unit;
performing simulation calculation on the relationship between the fin pitch and the heat exchange amount of the air cooler;
combining CO according to the result of simulation calculation2And determining the fin spacing of the air cooler according to the operation parameters of the refrigerating system.
In a further preferred embodiment, the step of controlling the flow rate of the air-cooler by the electronic expansion valve includes the steps of:
acquiring simulation test data of the air cooler under different working conditions, wherein the simulation test data comprises outlet pressure data, temperature data, refrigerating capacity data and energy efficiency data;
fitting calculation is carried out on the simulation test data to obtain an opening control formula of the electronic expansion valve;
the opening degree control formula of the electronic expansion valve is as follows: k is T1 a + T2B + C, where K is the electronic expansion valve opening; t1 represents the air cooler outlet temperature; a represents the outlet temperature coefficient of the air cooler; t2 represents evaporator outlet temperature; b represents the evaporator outlet temperature coefficient; c represents an opening correction system;
and after the opening degree of the electronic expansion valve is calculated according to an opening degree control formula of the electronic expansion valve, the flow of the air cooler is controlled through the opening degree of the electronic expansion valve.
Further as a preferred embodiment, the method further comprises the following steps:
performing simulation calculation on a loop between the air cooler and the evaporator, and optimizing the loop between the air cooler and the evaporator according to a simulation calculation result;
calculating a first parameter of a heat exchange tube of the evaporator based on different specifications of tube diameters;
calculating a second parameter of the heat exchange tube of the air cooler based on different specifications of tube diameters;
according to the calculation result of the first parameter and the calculation result of the second parameter, combining CO2The structure of the refrigeration system determines the pipe diameter of the heat exchange pipe;
the circuit between the air cooler and the evaporator is optimized according to the determined heat exchange pipe.
Further as a preferred embodiment, the method further comprises the following steps:
CO control by gas-liquid separator2Suction pressure of the refrigeration system;
the lubricating oil is separated from the refrigerant by the heater.
Further as a preferred embodiment, the method further comprises the following steps:
carrying out real-time first monitoring on the working pressure of the compressor through a first high-voltage switch;
according to the first monitoring result and the pressure measurement value of the high-pressure sensor, the CO is measured2The refrigerating system carries out load adjustment;
carrying out real-time second monitoring on the working pressure of the compressor through a second high-voltage switch;
based on the result of the second monitoring and the pressure measurement of the high pressure sensor, for CO2The refrigeration system is controlled to be shut down;
carrying out real-time third monitoring on the working pressure of the compressor through a low-voltage switch;
according to the result of the third monitoring, for CO2The refrigeration system is shut down.
Further as a preferred embodiment, the method further comprises the following steps:
by CO2Concentration detector for CO2CO in refrigeration system2Carrying out real-time fourth monitoring on the concentration;
according to the result of the fourth monitoring, for CO2The refrigeration system is shut down.
Further as a preferred embodiment, the method further comprises the following steps:
calculating the pipe diameter thickness and the blasting pressure value based on a preset working pressure coefficient;
according to the calculated pipe diameter thickness and the explosion pressure value, for CO2The pipelines and refrigeration components of the refrigeration system are controlled for burst prevention.
Corresponding to the method of FIG. 1, the invention also provides CO for the medium-high speed railway vehicle2Refrigerant air conditioning unit comprising:
the first calculation module is used for calculating the outlet state and the flow of the compressor according to the outlet pressure of the evaporator based on the high energy efficiency ratio;
the second calculation module is used for calculating the inlet state of the evaporator according to the outlet pressure of the evaporator based on the high energy efficiency ratio;
a third calculation module for calculating an inlet state of the air cooler based on the evaporator outlet pressure of the energy-efficient ratio;
a fitting calculation module for fitting CO according to the outlet state of the compressor, the flow rate of the compressor, the inlet state of the evaporator and the inlet state of the air cooler2Performing fitting calculation on the operating parameters of the refrigeration system;
and the determining module is used for determining the parameters of the components with the high energy efficiency ratio according to the result of the fitting calculation, wherein the components comprise a compressor, an evaporator and an air cooler.
The air conditioner of the rail vehicle is greatly different from the common commercial and civil air conditioners, the air conditioner of the rail vehicle is a special air conditioning system specially used for a railway passenger train, and CO is2The refrigerant air conditioning unit is different from a common large railway air conditioning unit, and is characterized in that:
(1) the air conditioning unit of the railway vehicle is arranged on the moving railway vehicle and is in a high-speed motion state and a vibration impact state.
(2) The air conditioning unit of the railway vehicle is arranged on the top of the moving railway vehicle and is suitable for severe working environments such as sunshine, rain, ice, snow, cold, high temperature and the like.
(3) The rail vehicle has the characteristics of high personnel density, large window area, high solar radiation heat and the like in the carriage, so that the air conditioning unit can meet the requirement of comfort level in the carriage only by needing larger refrigerating capacity and fresh air supply capacity.
(4) When the air conditioning unit of the railway vehicle operates in a high-temperature environment, the air conditioning unit can be operated at a high load due to the huge refrigeration requirement in the carriage, a condenser of the unit can generate a large amount of heat at the moment, a condensing fan is needed to provide stronger wind power to discharge a large amount of heat in a condensing cavity out of the unit in time, otherwise, the internal pressure of a refrigeration system of the air conditioning unit is too high, so that the internal temperature of the carriage is too high, and the comfort level of passengers is seriously influenced.
(5) When the air conditioning unit of the railway vehicle runs at a high speed, the condensation air volume can be reduced along with the increase of the vehicle speed, and the condition that the refrigerating effect of the unit is reduced or the unit is broken down due to the overhigh internal pressure of a refrigerating system of the air conditioning unit when the air conditioning unit runs at the high speed, so that the comfort level of the carriage environment is influenced is prevented.
(6) The air conditioning unit of the railway vehicle is supplied with power by a train in a centralized way, so that the power supply capacity is limited on one hand, and the power supply cost is very high on the other hand. Therefore, the train has a strict limit on the total input power of the air conditioning unit. In order to meet the requirement of total input power and embody the design concept of energy saving and environmental protection, the air conditioning unit needs to improve the refrigeration efficiency as much as possible.
(7) The air conditioning unit for the railway vehicle is usually installed at the top of a carriage, noise generated by the air conditioning unit is easy to transmit into the carriage, and if the noise decibel is too high, the comfort level of the internal environment of the carriage can be influenced, so that low noise is an important index for measuring the performance of the air conditioning unit.
The invention adopts CO2As the refrigerant, the following obvious advantages are provided:
1)、ODP＝0,GWP≈0；
2) the latent heat of evaporation is large, and the refrigerating capacity per unit volume is quite large (the refrigerating capacity per unit volume is 1.58 times of NH3 at 0 ℃, and is 8.25 times and 5.12 times of R12 and R22);
3) low kinematic viscosity, CO at 0 ℃2The kinematic viscosity of the saturated liquid was only 5.2% of NH3, which is 23.8% of R12;
4) the adiabatic index is higher, namely 1.30, the compressor pressure ratio pi, namely PH/P0 is about 2.5-3.0, and the adiabatic index is lower than other refrigerant systems and is close to the optimal economic level;
5) the lubricating oil is suitable for various lubricating oil and common machine part materials;
6)、CO2low cost and no need of recycling.
At present, ordinary rail air conditioning units at home and abroad mainly adopt R134a and R407C transition type environment-friendly refrigerants. And CO2The refrigerant is mainly used for supermarket refrigeration equipment and heat pump equipment, and CO2The refrigerant has a low energy efficiency ratio of only about 1.5 in the air conditioning field, and has a low energy efficiency ratio and a low cooling capacity when the ambient temperature is high.
Conventional R134a, R407C, R410A refrigerant systems operate at a maximum pressure of 40 bar. CO 22The highest pressure of the refrigerant system is 140bar, which is more than 3 times of the common refrigerant.
CO2The refrigerant has less application in air conditioning, especially large refrigerating capacity CO2The air conditioning unit does not operate in civil and commercial use; due to the particularity of the operating environment of the track air conditioner and the high requirement on the performance of the air conditioner unit, CO is used2At present, no mature and reliable track air conditioning product is developed for the air conditioning unit of the passenger room.
The invention uses natural environment-friendly working medium CO2The air conditioner is a refrigerant and is suitable for a large-refrigerating-capacity passenger room air conditioning unit for a railway vehicle with the normal speed and the speed per hour of more than 350 kilometers. The rated working condition refrigeration energy efficiency ratio of the air conditioning unit is more than 2.0, and the high-temperature working condition refrigeration capacity meets the standard requirements of TB1804-2017 air conditioning unit of railway passenger car.
The CO for high-speed railway vehicles according to the present invention will be described in detail2The specific implementation process of the refrigerant air conditioning unit comprises the following steps:
1) the lightweight design of the air conditioning unit is guaranteed, and the air conditioning unit is suitable for the requirements of installation space and weight of a high-speed motor train unit.
In particular, due to CO2The compressor of the air conditioning unit operates at ultrahigh pressure, so that the weight and the volume of the compressor are 40 percent heavier than those of the existing rail air conditioning unit adopting a totally-enclosed scroll compressor, the installation size is large, and CO is generated2Air conditioning unit overall dimension and air duct interface and conventionalLike air conditioning units, the interior space is limited and the weight of the unit is limited by the weight of the vehicle components, which is a consideration in terms of construction and component selection. In the design, light aluminum alloy is adopted as a main material for main indoor fans and outdoor fan components, so that the components are light; the air conditioning unit object adopts high-strength light aluminum profiles and aluminum plates to replace stainless steel materials, and ensures CO through the lightweight design of the materials2The weight of the air conditioning unit is basically consistent with that of the unit, and the requirement of the internal space of the air conditioning unit is met by optimizing the structure and the layout of components.
2) And the energy efficiency ratio of the unit is improved.
In particular, CO2The energy efficiency ratio of the refrigerant in the air conditioning system is low, generally about 1.5, and the energy efficiency ratio of the unit is higher than 2.0 due to the limitation of the capacity of the main machine. In order to meet the requirement of the energy efficiency ratio of the system, the invention adopts the CO-based method2The simulation calculation of the refrigerant characteristic and the simulation optimization calculation adopt a supposition substitution backward simulation calculation method, and the method combines the calculation of a refrigeration system and the performance calculation of a heat exchanger.
First, according to CO2Firstly, the outlet working state point of an evaporator when the energy efficiency ratio is high is assumed by the heat exchange characteristic of the refrigerant and the working characteristic of the compressor;
then, calculating the outlet states of each part of the compressor, the evaporator and the air cooler by backward simulation;
then, after the outlet states of all the parts are confirmed, fitting calculation is carried out on the outlet states and the operation parameters of the whole refrigeration system, and the parameters of the designed parts are preliminarily selected according to the fitting calculation results;
and finally, performing optimization fitting calculation on the component parameters according to the primary fitting calculation result.
Specifically, according to the result of the refitting calculation, 3 groups of optimal matching data close to the optimal working state point of the compressor are selected, three prototype machines are manufactured according to the 3 groups of optimal matching data to carry out system performance test, the test data of the prototype machines are compared with the simulation data, the design is further improved, and finally the energy efficiency ratio of the unit is up to 2.0.
3) The reliability and the comfort of the refrigeration of the air conditioning unit are ensured, and the excessive attenuation of the refrigeration performance when the temperature is high is prevented.
In particular, CO2The refrigerating capacity of the refrigerant is easy to attenuate during high-temperature refrigeration, and the high-temperature load of the rail air conditioner is large, so that the high-temperature refrigeration effect is required to be good, and the attenuation requirement of the traditional refrigerant for high-temperature refrigeration is less than about 10%. In order to ensure the high-temperature refrigeration performance, the invention ensures that the refrigeration system is in the optimal working point state in the high-temperature state by optimizing the flow path and the air resistance design of the condenser and adopting the electronic expansion valve and the variable flow control technology, thereby ensuring that the attenuation of the high-temperature refrigeration capacity of the air conditioning unit is less than 10 percent.
CO of the invention2When the refrigerant is cooled by the air cooler, the refrigerant outlet temperature of the air cooler is kept close to the ambient temperature in an ideal state; CO 22The refrigerant has high temperature and small specific heat capacity at the inlet of the air cooler and is cooled by CO2The temperature difference between the gas and the cooling air is large, the cooling speed is high, the specific heat capacity in a critical area is large, the temperature is reduced slowly, and according to the characteristic, the flow direction of the gas cooler is improved.
Meanwhile, according to the structure of the air conditioning unit, the mounting angle of the air cooler is adjusted, the critical zone process is ensured to be on the maximum windward side, and heat flow interference is avoided. In addition, the invention carries out analog calculation on the relationship between the fin pitch of the air cooler and the heat exchange quantity, and selects the fin pitch by combining the surface airflow relationship under different speeds of the air conditioning unit, thereby ensuring that the cooling effect of the air cooler is in the best heat exchange state when the air conditioning unit is at high speed and high temperature.
Wherein, CO2The invention firstly tests the outlet pressure, temperature, refrigerating capacity and energy efficiency data of the air cooler of the air conditioning unit under various different working conditions by simulation, and performs fitting calculation on the data to obtain an electronic expansion valve opening degree control formula K & ltT & gt A & lt + & gtB and K are the opening degree of the electronic expansion valve, T is the outlet temperature of the air cooler, and the temperature system A and the opening degree correction system B are adopted. And then according to the outlet temperature range of the air cooler, the opening degree of the electronic expansion valve is divided into three gears of high, middle and low, and the corresponding A, B coefficients are different, so that the variable flow control of the refrigeration system is realized by controlling the opening degree of the electronic expansion valve, and the operating pressure of the refrigeration system is in the optimal pressure under different working conditions.
4) The oil return amount of the compressor during refrigeration is controlled, the phenomenon of oil shortage of the compressor is prevented, the bad phenomena of overheating fault and the like of the compressor are avoided, and the air conditioning unit can work reliably for a long time.
In particular, due to CO2Due to the characteristics of the refrigerant, the refrigerant in the evaporator is easy to dry, so that lubricating oil is retained in the evaporator, the oil shortage of the compressor is easy to cause, the exhaust temperature of the compressor is overhigh, the compressor is overheated, and the long-time operation cannot be effectively and reliably carried out; meanwhile, the refrigerant is retained in the evaporator, which easily causes the rapid deterioration of the heat exchange effect and affects the comfort of the air conditioner.
The invention carries out optimization design and simulation calculation on a loop between the air cooler and the evaporator:
firstly, calculating the diameters of an air cooler and an evaporator by adopting different diameters, and calculating the heat exchange performance of an evaporator heat exchange tube by adopting heat exchange tubes with the diameters of 9.52mm, 8mm, 7mm and 5mm according to the pressure condition of a system; calculating the air cooler by adopting heat exchange tubes with the diameters of 8mm, 7mm and 5 mm;
then, by comparing the flow velocity, flow resistance, heat exchange coefficient and head-on wind speed of the refrigerants of the heat exchangers with different pipe diameters and combining the structure and the use characteristics of the air conditioning unit, the air cooler and the evaporator of the embodiment adopt heat exchange copper pipes with the diameter of 7 mm;
then, the air cooler and evaporator circuits are optimized to maintain reasonable flow rate of refrigerant in the evaporator and the air cooler, so that the lubricating oil in the system can flow back to the compressor with the refrigerant effectively.
The invention also arranges a gas-liquid separator in the refrigeration system, which can effectively stabilizeThe flow of the refrigerant of the system is fixed, and the phenomenon of drying of the refrigerant in the evaporator is avoided. According to the invention, the CO2The refrigerant characteristic and the lubricating oil characteristic are filled with proper amount of refrigerant, so that the effective flow of the refrigerant is ensured, and the lubricating oil is fully driven to return to the compressor.
In addition, the crankcase of the compressor is provided with the heater with certain power, so that the lubricating oil and the refrigerant are ensured to be fully separated, and the lubricating oil is reduced from entering the refrigeration system part through the refrigerant.
Therefore, the lubricating performance of the compressor can be fully ensured by the measures, the overheat fault of the compressor caused by oil shortage is avoided, and the reliable and effective operation of the compressor for a long time is effectively ensured.
5) The safe operation of the refrigeration system under the high-pressure or low-pressure working condition is ensured.
In particular, CO2The highest working pressure of the refrigerant air conditioning unit is 140bar, and the normal working pressure is below 120 bar. In order to ensure that the system pressure is in a normal range and prevent the working pressure of the system from exceeding a design range, a 2-level high-voltage switch and a high-voltage pressure sensor are arranged in a refrigerating system, and when a 1-level high-voltage alarm occurs in the system, the refrigerating system can automatically adjust the load capacity of the system according to the pressure value measured by the high-voltage pressure sensor so as to enable a compressor to be in a relatively low working pressure range; when the operation pressure exceeds the action value of a 2-stage high-voltage switch, the air conditioning system stops the operation of the compressor to prevent the system from working outside the designed pressure range; in addition, when the 2-stage high-voltage switch fails and the high-voltage pressure sensor detects that the system pressure exceeds the working range, the compressor can also be stopped to prevent the pressure from being ultrahigh. Furthermore, when the system pressure of the refrigeration system is lower than the working range, the invention can stop the compressor to avoid the damage of the machine.
Therefore, the system can be ensured to safely operate at high voltage through 3-level protection measures.
6) And carrying out anti-burst control on the refrigerating system.
In particular, CO2The highest working pressure of the refrigerant air conditioning unit is 140bar, so that the requirement on the pressure resistance of a refrigerating system is high, and the refrigerant air conditioning unit is designed according to the pipe diameterThe thickness calculation method comprises the following steps: δ ═ P × K1 × d0/(2 σ η +2Yp) + a, where δ represents the tube wall thickness; p represents a preset working pressure, i.e. a preset working pressure coefficient; d0 represents the tube outside diameter; sigma represents allowable force of the pipe; eta represents allowable force coefficient; y represents a temperature correction coefficient; a represents the amount of corrosion; k1 represents the wall thickness design factor. The working pressure coefficient of the conventional pipeline design is 1.1, and in CO2The design working pressure coefficient of a refrigeration pipeline system and components is 1.2, so that the safety coefficient of the pipeline components of the refrigeration system is improved by 20%, and the safety coefficient of the pipeline components of the refrigeration system is also improved within the service life of equipment.
Then, the invention calculates the blasting pressure value P: p ═ 2 × σ t/(D-0.8t), where t represents the minimum wall thickness and D represents the tube outside diameter; σ represents the tensile strength of the material. The invention ensures that the wall thicknesses of the system pipeline and the pipe of the refrigeration part meet the requirement of 3 times of working pressure, ensures that the hydraulic bursting pressure of the refrigeration system pipeline and the refrigeration part meets the design requirement of 3 times of working pressure, and ensures that the design hydraulic bursting strength of the conventional pipeline is 2.5-3 times.
7) The leakage amount of the refrigerant is ensured to be in a safe range.
CO2The refrigerant is a suffocation gas, and it is very important to prevent the refrigerant from leaking into the vehicle compartment. In order to ensure the tightness of the system, the pipeline of the refrigeration system adopts welding seal.
In addition, the refrigeration system of the present invention is provided with CO2The concentration detector can automatically stop the unit from running when the detection system leaks, and close the corresponding air door to prevent the refrigerant from entering the carriage, so that the leakage amount of the refrigerant is ensured to be within a safe range.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. CO for medium and high speed rail vehicle2Refrigerant air conditioning unit, characterised byIn that, the following aspects are included:
the air conditioning unit adopts natural environment-friendly working medium CO2As a refrigerant;
the air conditioning unit is used for a rail vehicle air conditioning system;
the air conditioning unit is suitable for the rail vehicle with the speed per hour of more than 350 kilometers;
CO for medium and high speed rail vehicle2The energy efficiency ratio of the refrigerant air conditioning unit is more than 2.0;
CO2the highest operation pressure of the refrigerant air conditioning unit is 140 bar;
CO2the highest operating environment temperature of the air conditioning unit reaches 50 ℃;
CO2the air conditioning unit adopts a lightweight design technology.
2. CO for medium and high speed rail vehicle2A method of refrigerant air conditioning units characterized by: the method comprises the following steps:
calculating the outlet state and the flow of the compressor based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
calculating the inlet state of the evaporator based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
calculating the inlet state of the air cooler based on the outlet pressure of the evaporator with the preset high energy efficiency ratio;
according to the outlet state of the compressor, the flow rate of the compressor, the inlet state of the evaporator and the inlet state of the air cooler, which are obtained through calculation, for CO2Performing fitting calculation on the operating parameters of the refrigeration system;
and determining parameters of components of the high energy efficiency ratio according to the fitting calculation result, wherein the components comprise a compressor, an evaporator and an air cooler.
3. CO for medium and high speed rail vehicles according to claim 22A method of refrigerant air conditioning units characterized by: further comprising the steps of:
designing the flow direction of the air cooler into a cross S shape, and increasing the cooling speed of a critical zone of the air cooler through a countercurrent design;
controlling the flow rate of the air cooler through an electronic expansion valve;
dynamically adjusting the installation angle of the air cooler according to the structure of the air conditioning unit;
performing simulation calculation on the relationship between the fin pitch and the heat exchange amount of the air cooler;
combining CO according to the result of simulation calculation2And determining the fin spacing of the air cooler according to the operation parameters of the refrigerating system.
4. CO for medium and high speed rail vehicles according to claim 22A method of refrigerant air conditioning units characterized by: the step of controlling the flow rate of the air cooler by the electronic expansion valve includes the steps of:
acquiring simulation test data of the air cooler under different working conditions, wherein the simulation test data comprises outlet pressure data, temperature data, refrigerating capacity data and energy efficiency data;
fitting calculation is carried out on the simulation test data to obtain an opening control formula of the electronic expansion valve;
the opening degree control formula of the electronic expansion valve is as follows: k is T1 a + T2B + C, where K is the electronic expansion valve opening; wherein T1 represents the air cooler outlet temperature; a represents the outlet temperature coefficient of the air cooler; t2 represents evaporator outlet temperature; b represents the evaporator outlet temperature coefficient; c represents an opening correction system;
and after the opening degree of the electronic expansion valve is calculated according to an opening degree control formula of the electronic expansion valve, the flow of the air cooler is controlled through the opening degree of the electronic expansion valve.
5. CO for medium and high speed rail vehicles according to claim 22A method of refrigerant air conditioning units characterized by: further comprising the steps of:
performing simulation calculation on a loop between the air cooler and the evaporator, and optimizing the loop between the air cooler and the evaporator according to a simulation calculation result;
calculating a first parameter of a heat exchange tube of the evaporator based on different specifications of tube diameters;
calculating a second parameter of the heat exchange tube of the air cooler based on different specifications of tube diameters;
according to the calculation result of the first parameter and the calculation result of the second parameter, combining CO2The structure of the refrigeration system determines the pipe diameter of the heat exchange pipe;
the circuit between the air cooler and the evaporator is optimized according to the determined heat exchange pipe.
6. CO for medium and high speed rail vehicles according to claim 22A method of refrigerant air conditioning units characterized by: further comprising the steps of:
CO control by gas-liquid separator2Suction pressure of the refrigeration system;
the lubricating oil is separated from the refrigerant by the heater.
7. CO for medium and high speed rail vehicles according to claim 22A method of refrigerant air conditioning units characterized by: further comprising the steps of:
carrying out real-time first monitoring on the working pressure of the compressor through a first high-voltage switch;
according to the first monitoring result and the pressure measurement value of the high-pressure sensor, the CO is measured2The refrigerating system carries out load adjustment;
carrying out real-time second monitoring on the working pressure of the compressor through a second high-voltage switch;
based on the result of the second monitoring and the pressure measurement of the high pressure sensor, for CO2The refrigeration system is controlled to be shut down;
carrying out real-time third monitoring on the working pressure of the compressor through a low-voltage switch;
according to the result of the third monitoring, for CO2The refrigeration system is shut down.
8. CO for medium and high speed rail vehicles according to claim 22A method of refrigerant air conditioning units characterized by: further comprising the steps of:
by CO2Concentration detector for CO2CO in refrigeration system2Carrying out real-time fourth monitoring on the concentration;
according to the result of the fourth monitoring, for CO2The refrigeration system is shut down.
9. CO for medium and high speed rail vehicles according to claim 22A method of refrigerant air conditioning units characterized by: further comprising the steps of:
calculating the pipe diameter thickness and the blasting pressure value based on a preset working pressure coefficient;
according to the calculated pipe diameter thickness and the explosion pressure value, for CO2The pipelines and refrigeration components of the refrigeration system are controlled for burst prevention.
10. CO for medium and high speed rail vehicle2Refrigerant air conditioning unit, its characterized in that: the method comprises the following steps:
the first calculation module is used for calculating the outlet state and the flow of the compressor according to the outlet pressure of the evaporator based on the high energy efficiency ratio;
the second calculation module is used for calculating the inlet state of the evaporator according to the outlet pressure of the evaporator based on the high energy efficiency ratio;
a third calculation module for calculating an inlet state of the air cooler based on the evaporator outlet pressure of the energy-efficient ratio;
a fitting calculation module for fitting CO according to the outlet state of the compressor, the flow rate of the compressor, the inlet state of the evaporator and the inlet state of the air cooler2Performing fitting calculation on the operating parameters of the refrigeration system;
and the determining module is used for determining the parameters of the components with the high energy efficiency ratio according to the result of the fitting calculation, wherein the components comprise a compressor, an evaporator and an air cooler.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113525437A (en) * | 2021-06-30 | 2021-10-22 | 广州鼎汉轨道交通车辆装备有限公司 | R744 refrigerant heat pump air conditioning unit, system and control method thereof |
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Application publication date: 20210205 |