Research On Performance Monitoring And Analysis Methods Of Aircraft Heat Exchangers

The working state of the aircraft air conditioning system is closely related to the passenger's experience.The heat exchanger is an important component of the air conditioning system,and its performance changes have a huge impact on the air conditioning system.When entered the spring and summer,the ash and other pollutants in the air increased,the air conditioning system of civil aviation aircraft frequently occurs thermal protection shutdown failure in ground conditions.It has been found that heat exchanger fouling in aircraft air-conditioning systems is one of the main causes of this phenomenon.In this context,this thesis takes the plate-fin heat exchanger as the research object,and conducts an in-depth study on the performance monitoring and analysis method of the heat exchanger based on air pollution:Firstly,the simulation model of the aircraft refrigeration system is established and the influence law of different factors on the performance of the heat exchanger is analyzed based on this model.Then the influence weights of different factors on the performance of the heat exchanger are analyzed and the heat exchanger performance prediction method is proposed.Finally,a heat exchanger performance monitoring system was established.The specific research contents are as follows:Based on the Flowmaster platform,the mathematical model of the main components of aircraft refrigeration system is established,and the simulation model of aircraft refrigeration system is built.Based on this model,the influences of three factors,namely ambient temperature,inlet air pressure of refrigeration system and fouling thickness of heat exchanger,on the performance of the heat exchanger are analyzed.A prediction model of fouling thickness based on improved BP neural network is established,which realizes the prediction of the thickness of the heat exchanger fouling based on the ambient temperature,the inlet air pressure of the refrigeration system,the outlet temperature of the primary heat exchanger,and the outlet temperature of the secondary heat exchanger.The analytic hierarchy process is used to analyze the weight distribution of the three factors of ambient temperature,air pressure at the inlet of the refrigeration system and the thickness of the fouling on the performance of the heat exchanger,and to predict the performance of the heat exchanger.An aircraft heat exchanger performance monitoring system is designed,it can not only collect the parameters related to the heat exchanger,but also send the data to the upper computer through Wi-Fi communication.It can also read,analyze and store data from the upper computer,and finally realize the monitoring of heat exchanger performance.After testing,the prediction method of heat exchanger performance is reliable,and the system can realize the monitoring of heat exchanger performance stably,and manage the data,which can provide help for monitoring the performance of heat exchanger during off-site maintenance.