Fault diagnosis of aircraft heat exchangers based on RELS method

Dynamic simulation of a triangle fin heat exchanger utilized in Aircraft Environment Control System (AECS) was performed. The physical parameters of heat exchanger have been identified using the Recursive Extended Least Squares (RELS) method. Then the behaviors of the heat exchanger with single/double faults were simulated and changes of the physical parameters from normal to fault conditions were analyzed. Then simulations were carried out with the given input and output data, and fault detection and fault isolation were done through the identification of changes of parameters. It is indicated that the RELS method is feasible for fault diagnosis. The relationship between the changes of physical parameters and the fault modes provides a useful approach to define the faults and can be extend to heat exchangers applied in practical engineering.