Methods in S.I. Engine Modelling: Auto-calibration of Combustion and Heat Transfer Models, and Exergy Analysis

Sami M. M. E. Ayad, Carlos R. P. Belchior, José R. Sodré

Research output: Chapter in Book/Published conference outputChapter


This chapter reports on a workflow aimed at obtaining deeper insights into spark ignition engines using thermodynamic modelling. This workflow is divided into two steps: (i) Auto-calibration of combustion and heat transfer models using AVL Boost® and AVL Design Explorer; and (ii) in-cylinder exergy analysis using Wolfram Mathematica®. Model calibration is usually based on experimental pressure curve and combustion data. However, there is a gap in methods that generate accurate simulation results, while calibrating the combustion and heat transfer models without prior experimental results. Thus, the authors proposed an approach in their earlier work to address this gap. In this chapter, this proposed approach has been complemented with exergy analysis to form a complete workflow for engine research using simulation. This workflow was applied to a 4-cylinder gasoline engine template model as a case study. First, the combustion and heat transfer models are parametrized and used as design variables of an optimization problem. The objective functions in this problem are the combustion phasing, here defined as the crank angle in which the peak cylinder pressure occurs CApp, and the mechanical load, here defined as the indicated mean effective pressure IMEP. The appropriate temperature constraints were included to guarantee that the engine model was representative of the physical problem. The optimization problem is then solved for a target IMEP and CApp and the results are analyzed. Afterwards, we begin the exergy analysis of the engine to obtain deeper insights. The resulting curves for the thermodynamic state properties and species’ molar fraction are exported from the simulation software to a program in Wolfram Mathematica that does the exergy analysis of the engine, providing deeper insights into the useful work available in the engine, losses due to heat transfer, losses in the exhaust gases, and combustion irreversibilities. This analysis can be very useful in determining the best fuel mixture, operating conditions, and areas for improvement.
Original languageEnglish
Title of host publicationEngine Modeling and Simulation. Energy, Environment, and Sustainability
EditorsA.K. Agarwal, D. Kumar, N. Sharma, U. Sonawane
Number of pages32
ISBN (Electronic)978-981-16-8618-4
ISBN (Print)978-981-16-8617-7
Publication statusPublished - 17 Dec 2021

Publication series

NameEngine Modeling and Simulation
ISSN (Print)2522-8366
ISSN (Electronic)2522-8374


  • Calibration model
  • Cylinder pressure
  • Engine modelling
  • Engine simulation
  • Exergy analysis
  • Spark ignition engine


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