Numerical study of compression ratio influence on specific fuel consumption of an ethanol fueled engine using GT POWER code

The transportation sector is responsible for 24% of CO2 global emissions and great effort has been made by the scientific community to replace the use of fossil fuels with renewables. Brazil has committed to implement all obligations provided in COP26 seeking carbon neutrality in the set of economic activities. In this regard, Brazil has agreed in reducing GHG by 50% until 2030. Flexfuel technology was introduced in the Brazilian market decreasing fuel conversion efficiency due to the use of an intermediary compression ratio value, lower in comparison with the best value for engines exclusively fueled with ethanol and higher for gasoline. According to data published by INMETRO, flexfuel engine consumption has increased around 6%. Many European countries have been pointing to the electrification of the light vehicle as a solution to mitigate GHG, which is neither best nor a feasible solution for the future of Brazilian mobility. Brazil has an average of 5000 Wh/m² of solar irradiation per day having 66.3 million hectares of cultivated land (only 7.8% of the national territory), therefore a much higher biomass production capacity compared to Europe. With a well-developed ethanol distribution network, this biofuel is the most viable solution for the Brazilian fleet. In this matter, a 1D mathematical model in GT-Power is proposed, calibrated and validated to study the influence of the volumetric compression ratio on the specific fuel consumption of a bioethanol fueled engine, with numerical errors of less than 5%. The compression ratio varied between 11.5:1, 13.0:1 and 15.0:1, with the simulations being performed at partial load of 1000 and 2500 RPM. Maximum fuel conversion efficiency was achieved at a volumetric compression ratio of 15.0:1, with a reduction in specific consumption approaching 4%, which is due to the chemical and physical properties of ethanol that allowed the engine to operate in MBT for all loads and speeds.