Application of system identification techniques to performance monitoring of four stroke turbocharged diesel engines

摘要

The thesis has two main objectives; firstly to mathematically model, simulate the performance and carry out a theoretical sensitivity analysis, and secondly to evaluate a new method for condition monitoring of four stroke turbocharged diesel engines based on system identification techniques and parameter estimation. Fault detection and diagnosis are illustrated by application of off-line parameter estimation techniques to a non-linear model of diesel engines. A recursive prediction error method was used to estimate parameters, corresponding to faults in a lumped parameter system. The results clearly indicate the feasibility of fault detection as well as diagnosis, that is, discrimination among faults occuring approximately at the same time. Among the objectives of early detection of malfunctions are the prevention of sudden failure of equipment, the improved planning of maintenance and performance. Measurements of dynamic cylinder pressures and mean values of compressor outlet temperature, air receiver pressure and temperature, exhaust receiver pressure and temperature, engine speed, turbine outlet temperature and turbocharger speed are used as input to the program. Bearing in mind the simple mathematical model of the diesel engine, the predicted variables show quite good agreement with measurements. A number of faults were investigated experimentally both individually and as multiple faults in order to test the method. Results showed that some of the parameters were more sensitive for detecting faults than the more traditionally used methods of trending measured variables. 111 refs., 59 figs., 36 tabs.