Fault Analysis Of Airborne Refrigeration System Based On FMECA And FTA

With the continuous development of time and technology, the airborne refrigeration system play an increasingly significant role.At the same time upgrading of airborne refrigeration system greatly improve its complexity.Airborne refrigeration system in the process of running would inevitably fail, and in order to improve the reliability and security of airborne refrigeration system, it is exceedingly necessary to analyze and diagnose the faults of airborne refrigeration system. For the airborne refrigeration system, this paper uses methods which are the Failure Mode Effects and Criticality Analysis(FMECA) and Fault Tree Analysis(FTA), combined with MATLAB/SIMULINK simulation platform, carries out the fault anslysis about the airborne refrigeration system. This work mainly revolves around the following aspects:(1) To analyze the principle of airborne refrigeration system, determine main components of system and fault logic relationship between them. According to military standard, this paper has collected the relevant data, made tables and proceeded analysis of main components' FMECA including the heat exchanger, water separator, valve, sensor and turbine.(2) On the basis of FMECA, it is applied the method of FTA to set up the the fault tree models which are parts, abnormal cabin temperature and abnormal cabin pressure as the top event, analyzing these fault trees and gaining the fault sorts. Analysis results show that turbine failure is the main reason for the cockpit temperature higher than the comfort zone temperature, and the cabin temperature is lower than the comfort zone due to temperature regulating valve failure, and resulting in abnormal cabin pressure is pressure sensor malfunction.(3) It has set up a simulating model and fault simulation for the entire airborne refrigeration system. According to the cockpit ventilation temperature combined with severity, system failure is defined using efficiency of components, providing the failure criterion for fault simulation. By simulation calculation on different working conditions of airborne refrigeration system, a single part failure export parameter data are gained, establishing airborne refrigeration system fault database. Through monitoring and comparison of the parts exports parameters, the failure causes and failure sorts can be quickly found. This shows that it is feasible to use efficiency of parts to quantify different severity for the cockpit ventilation temperature as the failure criterio.