Effects of gasoline composition on engine performance, exhaust gases and operational costs

Abstract

New technologies to improve the performance and efficiency of internal combustion engines are related to enhance knock resistance in fuels. Aromatics, Paraffins and Lead-based additives in gasoline are used to increase octane rating, but some of these are toxic, carcinogenic or expensive. Nowadays, several alternatives for octane boosting is considered and oxygenated compounds are attracting interest, as ethanol. This compound is a renewable energy source, which can reduce the oil dependence and also can be appropriately used in gasolines as a blend. Ethanol use, widely noticed in Brazil and United States, increase octane rating, thermal efficiency and engine power due to the charge cooling effect and molar expansion capacity. For the same engine and operation conditions, octane rating and engine performance are directly correlated. The present study discusses about the influence of gasoline blend composition on the engine performance by the combustion process analysis. For this, samples of gasoline blends with different RON numbers were experimentally evaluated on a single cylinder research engine in high load and speed conditions. These conditions were selected as they are potential operation points for knock occurrence. The results show that despite the increase in aromatic content of gasoline samples and consequently the improvements in octane rating and engine performance, it is not compensated by the cost. For instance, the use of gasoline blend with higher ethanol percentage, resulted in reduction of more than 23% in net power (kW) cost and up to 32% of NOx specific emission.