Investigations of engine characteristics by exhaust gases composition change
2018
Salova, T., Saint-Petersburg State Agrarian Univ. (Russian Federation) | Ostyuchenko, I., Saint-Petersburg State Agrarian Univ. (Russian Federation)
For diagnostics of engines running, the operational characteristics are used, which are combined with the characteristics of the change in the exhaust gas composition. The implementation of driving cycles requires expensive equipment, the use of which demands significant costs. In the developed research methodology, it is proposed to use the simplification of the test system, replacing the driving cycles with equivalent test regimes, that is, from the acceleration modes to the equivalent modes that can be realized in bench tests. Each equivalent mode is calculated by the combination of two factors: the car speed and the power of resistance to vehicle movement. Values of concentration of harmful substances in exhaust gas at equivalent modes determine the level of car emissions. The composition of the exhaust gas at these modes, when compared with the calculated values of the components of the exhaust gas, makes it possible to select factors that affect the change in the course of the engine processes. In the developed model, the processes of mixture formation and combustion are considered as multi-phase processes of a multicomponent system. The process model is represented as the set of possible states of a real non-equilibrium process on the way to the final equilibrium state. The state of the final equilibrium of the combustion process is determined by the minimum value of the Gibbs function, when the material balance of the system is satisfied for the conditions T, P = const. The developed model simplifies the procedure for calculating the composition of exhaust gas, since the calculation is based on the temperature of exhaust gas instead of the temperature of the combustion process. The methodology for calculating of exhaust gases composition can be realized for various heat engines; and allows to predict and carry out diagnostics of the engine fuel system.
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