TY - JOUR N2 - The engine simulations have become an integral part of engine design and development. They are based on approximations and assumptions. The precision of the results depends on the accuracy of these hypotheses. The simplified models of frozen composition, chemical equilibrium and chemical kinetics provide the compositions of combustion products for engine cycle simulations. This paper evaluates the effects of different operating conditions and hypotheses on the exergetic analysis of a spark-ignition engine. The Brazilian automotive market has the highest number of flex-fuel vehicles. Therefore, a flex-fuel engine is considered for simulations in order to demonstrate the effects of these different hypotheses. The stroke length and bore diameter have the same value of 80 mm. The in-cylinder irreversibility is calculated for each case at the closed part of the engine cycle. A comparative analysis of these hypotheses provides a comprehensive evaluation of their effects on exergetic analysis. Higher values of accumulated irreversibility are observed for the oversimplified hypothesis. L1 - http://www.czasopisma.pan.pl/Content/113070/PDF/02_paper.pdf L2 - http://www.czasopisma.pan.pl/Content/113070 PY - 2019 IS - No 3 EP - 42 DO - 10.24425/ather.2019.129548 KW - Engine simulations KW - Combustion products KW - Spark-ignition engines KW - Ethanol KW - Irreversibility A1 - Rufino, Caio H. A1 - de Lima, Alessandro J.T.B. A1 - Mattos, Ana P. A1 - Allah, Fazal U.M. A1 - Ferreira, Janito V. A1 - Gallo, Waldyr L.R. PB - The Committee of Thermodynamics and Combustion of the Polish Academy of Sciences and The Institute of Fluid-Flow Machinery Polish Academy of Sciences VL - vol. 40 DA - 2019.09.27 T1 - Effects of combustion products composition models on the exergetic analysis of spark-ignition engine fuelled with ethanol SP - 27 UR - http://www.czasopisma.pan.pl/dlibra/publication/edition/113070 T2 - Archives of Thermodynamics ER -