A chemical kinetics model to predict lubricant performance in a diesel engine. Part I: Simulation methodology
C I. Chen, Stephen M. Hsu
The ability of the lubricant to protect the increasingly complex diesel engines directly affects engine durability and warranty costs and is becoming increasing costly to validate. This paper presents a novel approach to evaluate lubricant performance in a given diesel engine. A mathematic model has been developed to predict the performance of a given lubricant in a given diesel engine design. Chemical kinetic constants were obtained using specifically designed bench tests and the model using these constants is capable of predicting engine deposit and oil consumption rate. The model is validated by using results from some Caterpillar 1K engine tests. For a given engine, three chemical reactors are identified: the oil sump, the top piston ring groove, and the piston cylinder-liner interface. Oil flows from one reactor to another as dictated by the engine design. The oxidation process is described by chemical kinetic rate equations with the kinetic constants of the lubricants independently determined by specifically designed laboratory bench tests, such as DSC, TGA, and Micro-Oxidation tests. The design and the operating conditions of the engine define the chemical reaction parameters such as the temperatures of the reactions, the residence time in a particular reactor, the volume of the reactors, and the materials used in the engine, etc. A computer simulation program has been written to calculate oilconsumption and the generation of deposit according to the kinetic equations. Two experimental high temperature lubricants and three 1K reference oils were used in this study. Good agreements between simulation and 1K engine test results were obtained.