Abstract
A truly universal system to optimize consumptions, monitor operation and predict maintenance interventions for internal combustion engines must be independent of onboard systems, if present. One of the least invasive methods of detecting engine performance involves the measurement of the exhaust gas temperature (EGT), which can be related to the instant torque through thermodynamic relations. The practical implementation of such a system requires great care since its torque-predictive capabilities are strongly influenced by the position chosen for the temperature-detection point(s) along the exhaust line, specific for each engine, the type of installation for the thermocouples, and the thermal characteristics of the interposed materials. After performing some preliminary tests at the dynamometric brake on a compression-ignition engine for agricultural purposes equipped with three thermocouples at different points in the exhaust duct, a novel procedure was developed to: (1) tune a CFD-FVM-model of the exhaust pipe and determine many unknown thermodynamic parameters concerning the engine (including the real EGT at the exhaust valve outlet in some engine operative conditions), (2) use the CFD-FVM results to considerably increase the predictive capability of an indirect torque-detection strategy based on the EGT. The joint use of the CFD-FVM software, Response Surface Method, and specific optimization algorithms was fundamental to these aims and granted the experimenters a full mastery of systems’ non-linearity and a maximum relative error on the torque estimations of 2.9%.
Highlights
IntroductionSustainability is one of the master keywords that will lead world development during the years
This study proposes a general procedure whose main purpose is to improve the accuracy of the indirect prediction of the torque delivered by a compression-ignition engine for agricultural purposes from a series of temperatures measured along the exhaust pipe through three thermocouples freely placed on it
Thanks to a merit function defined for this purpose, it has been possible to individuate the best values of a set of physical parameters related to heat transfer in the three-dimensional domain so as to have a computational fluid dynamics (CFD)-finite volume method (FVM) model fully aligned with the experimental results
Summary
Sustainability is one of the master keywords that will lead world development during the years. Pollution derived from the use of fossil fuels and possible consequent climate changes are two of the most debated arguments nowadays and, because of this, the entire economic sector of internal combustion engines (ICEs), from their production to their use as power units, is one of the most involved in sustainability issues and sustainabilitycompliant strategies. To better frame the problem and its numerous aspects, ICEs are the main source of energy for the small-/medium-size cogeneration sector and the most common mean to move vehicles and to run industrial and agricultural devices, with traffic being one of the main sources of air pollution in our cities together with residential heating [1,2]. Improvements brought to ICEs will result in a worldwide positive effect, and this motivates the huge efforts undertaken to make ICEs more “eco-friendly”
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