Influence Of The Pipeline On The Performance Of Automotive Heat Pump Air Conditioning System

In recent years,the development of both power battery vehicles and fuel cell vehicles are very rapid.Heat pump air conditioning can effectively reduce the impact on the endurance mileage,and become the inevitable trend of the development of automotive air conditioning.The improvement of people's expectation of automobile comfort also promotes the improvement of air conditioning performance and sensitive control.At the same time,the electric vehicle air conditioning needs to take into account the safe operation of the battery and other system equipment,so the complex functional requirements bring about the complex air conditioning structure.This paper discusses the influence of the structure and layout of the air conditioning system pipeline on the performance of the heat pump air conditioning system.The air conditioning pipeline was originally only used as the air conditioning connector,which was responsible for connecting the four original air conditioning components.Because of the complexity of heat pump air conditioning,the pipeline is no longer a simple form of single in and single out.In the experiment,it is found that the pipeline has a great impact on the operation of air conditioning.In order to find out the real impact of the pipeline on the system under different operating conditions,this paper uses the combination of experiment and simulation.The type of air conditioning refrigerant determines the structural arrangement of the heat pump air conditioning system.Because of the great difference of thermos physical properties between different refrigerants,the components of air conditioning will also be very different.At present,R134 a is the commonly used refrigerant in the market,so R134 a is also the refrigerant selected in this paper.In this paper,the physical properties of R134 a and the flow pattern in the pipeline are analyzed and modeled theoretically.Based on the basic theory of thermodynamics and heat transfer,the flow state of refrigerant in different pipelines is studied and summarized.Secondly,in order to study the performance of the heat pump air-conditioning system more carefully,this paper rebuilt the platform for a certain vehicle heat pump airconditioning system,completely reducing the internal pipe layout of the electric vehicle.Sensors are installed in each position of the test bench,and the best data is obtained through the calibration test of heat pump and refrigeration conditions of this electric vehicle.And according to the data obtained for analysis.Experimental methods can only monitor the state of a limited number of points.In this paper,the simulation method is used to study the flow state of refrigerant in all pipelines.In order to ensure the accuracy of the simulation.Firstly,the pipeline of the experimental platform is modeled to ensure the accuracy of the simulation.At the same time,the temperature and pressure between the inlet and outlet of each part of the pipeline determined by the experimental data provide the initial conditions for the three-dimensional simulation,and analyze and compare the flow situation of the working medium in the pipeline.Through the research of simulation and experiment,it is found that the performance of the pipeline of heat pump air conditioning system is very different under different conditions.Compare the temperature,pressure and speed of each working condition,and analyze the loss of each section of pipeline.And it can also determine the unreasonable structure in the pipeline,and make a more in-depth discussion on these unreasonable structures.It also depends on CFD simulation technology to find a reasonable pipeline layout structure.The influence of pipeline on automotive heat pump air conditioning system is mainly the geometric dimension of pipeline,including the diameter,length,bending angle,branch pipe size and refrigerant flow.These unreasonable pipeline structures also have great room for improvement.