Thermodynamic modeling of combustion process of the internal combustion engines – an overview

Denys Stepanenko,Zbigniew Kneba

doi:10.19206/ce-2019-306

Abstract

The mathematical description of combustion process in the internal combustion engines is a very difficult task, due to the variety of phenomena that occurring in the engine from the moment when the fuel-air mixture ignites up to the moment when intake and exhaust valves beginning open. Modeling of the combustion process plays an important role in the engine simulation, which allows to predict in-cylinder pressure during the combustion, engine performance and environmental impact with high accuracy. The toxic emissions, which appears as a result of fuels combustion, are one of the main environmental problem and as a result the air pollutant regulations are increasingly stringent, what makes the investigation of the combustion process to be a relevant task.

Highlights

The combustion process in the internal combustion engines is a chemical reaction between the fuel and oxidant, with the emission of heat and light
The existing computational methods and computer programs that are most commonly used for modeling processes that are occurring inside ICE can be divided into two main categories: thermodynamic models. For this cell applies the mass, the energy and the state balance equations) and Computational Fluid Dynamic (CFD) models
According to the assumptions above, it can be concluded that Thermodynamic combustion models (TCM) – is used for energy analysis of the combustion process in the entire volume of the ICE cylinder and solves the issues in which can be assumed that the gas parameters are independent of coordinates and depend only on the time, the usage of TCM allows to analyze toxic emission during the combustion process

Summary

Introduction

The combustion process in the internal combustion engines is a chemical reaction between the fuel and oxidant, with the emission of heat and light. The existing computational methods and computer programs that are most commonly used for modeling processes that are occurring inside ICE can be divided into two main categories: thermodynamic models For this cell applies the mass, the energy and the state balance equations) and Computational Fluid Dynamic (CFD) models (engine elements are divided into a high number (hundreds of thousands) of three-dimensional cells and for each of them solved the systems of energy, mass, momentum and state balance equations. According to the assumptions above, it can be concluded that TCM – is used for energy analysis of the combustion process in the entire volume of the ICE cylinder and solves the issues in which can be assumed that the gas parameters are independent of coordinates and depend only on the time (or crankshaft angle), the usage of TCM allows to analyze toxic emission during the combustion process. General equations: 1. The first law of thermodynamics used to describe the processes occurring in the combustion chamber consists in the fact that the change of internal energy in the cylinder is equal to the sum of the work of the piston, the amount of heat and enthalpy in- or out-flowing gas (Eq 3)

TCM basic assumptions

Thermodynamic properties

The cylinder volume submodel

Heat transfer submodel

Conclusions