Sensitivity Analysis Applied to the Thermodynamic Diagnosis of Combustion in a Diesel Engine with DIAGNO-DIESEL® Software

Abstract

At present, in order to mitigate the environmental impact of internal combustion machines and to increase their efficiency, it is necessary to carry out thermodynamic studies to predict their mechanical, thermal, and environmental behavior under different operational conditions. Within the thermodynamic modeling of thermal machines, it is necessary to carry out a process of characterization of the device under study. This article proposes a methodology for the characterization of 4JJ1 Isuzu Diesel engines applying combustion diagnosis, where the pressure signal in the combustion chamber is input, which is measured experimentally based on the angle of the crankshaft and how Exit the heat release curve. A motored procedure, in which the heat transfer process has been adjusted to the combustion chamber walls of the engine under study, has been performed. With this characterization, it has been verified that the change in 10% of the heat transfer adjustment coefficient in the chamber leads to a maximum change of 0.8% in the heat release rate through a sensitivity analysis of the developed model. The mass retained at the closing of the admission has a more pronounced effect, where a 10% change in this variable causes a 4.2% change in the heat release rate. A 10% change in the compression ratio has been observed, causing a maximum change of 6.1% in the heat release rate. Changes in the constants for piezoelectric transducer measurement, pressure level reference and crank angle measurement result in less than 5% change in maximum heat release rate values estimated by the diagnostic model.