In the next 15 years, the Brazilian government faces the difficult task of honoring the environmental commitment assumed at COP21 to reduce in 43% the GHG emission contributing to the global warming effect. It also has the challenge of ensuring a sustainable fuel supply for the transport sector. In this scenario, the RenovaBio program gives the directives to promote the use of biofuels as an important source of energy.Besides the above-mentioned strategic aspects, the automotive market demands for the development of future technologies to improve the efficiency of the S.I. engines. With that in mind, the experimental work here described consisted of investigating the influence of the volumetric compression ratio, associated to internal EGR and airflow structure optimization (swirl and tumble) on the fuel consumption of a single cylinder research engine equipped with PFI and DI injection systems and running on E22 or hydrated ethanol.The conclusion of the present work will show that it is possible to improve the fuel conversion efficiency by increasing the volumetric compression ratios above the ones used in the passenger cars sold in Brazil, and that ethanol has many advantages over the fossil fuel due to its antiknocking properties and environment friendliness.
In this paper, we detail the development and goals of a brand new turboshaft engine called BEARCAT. “BEARCAT” is an acronyme for ‘’Banc d’Essai Avancé pour la Recherche en Combustion et Aérothermique des Turbomachines’’. BEARCAT is based on a MAKILA engine, a turboshaft developed by Safran Helicopter Engines (formerly Turboméca) and powering the H215 (2 Makila 1A1, 1820 SHP each) and the H225 (2 Makila 2A1, 2000 SHP each) of Airbus Helicopters. BEARCAT is developed by SAFRAN-Tech, the Research and Technology Center of the SAFRAN Group. This test engine is devoted to the fine characterization of aero-thermal phenomena occurring within the combustion chamber and the High Pressure Turbine as well as their interactions. Therefore, BEARCAT differs from a standard test engine by the implementation of metrologies inside the combustion chamber and the 2-stage High Pressure Turbine, in order to perform both steady and non-steady flow measurements which will be used to validate CFD codes and models. The engine instrumentation induces thorough modifications of several engine parts and also the development of original technical solutions to ensure metrologies integration in minimizing their impact on performances.
The use of exhaust gas recirculation in internal combustion engines, obtained by means of variable valve timing techniques, has represented a good alternative to reduce in-cylinder gas emission and the specific fuel consumption, consequently improving thermal efficiency. The control of valves opening and closing times, especially when keeping some overlapping, may permit the residual gases trapping, what makes the cylinder temperatures lower and reduce engine-out emissions, mainly of nitrogen oxides. Besides that, these techniques allow load control, what can eliminate the necessity of throttling and hence pumping losses. Based on this, this paper presents an analysis of the use of variable valve timing focused on trapping some residual gases in a spark ignition engine. It has been used a four valve Single Cylinder Research Engine-SCRE with direct injection. It was adopted a volumetric ratio equal to 15:1, an engine speed of 2500 rpm and the ethanol as fuel. Valves timing were changed taking into account the maximum fraction of exhaust gases which could be used without compromising mixture inflammability. Changes in performance were analyzed and the importance of controlling the amount of recycled exhaust gases was finally evidenced.
In order to mitigate the greenhouse gases emission from automobiles and to reduce the dependency on fossil fuels, various alternatives for replacing the internal combustion engine are available. However, the best solution for this dilemma must take into account the geographic and social-economic characteristics of the country, its energy matrix, its emission legislation, and the fuel carbon footprint during its entire lifecycle. Brazil has a strong reputation for its fleet of Flex-Fuel vehicles, long date experience in the use of ethanol fuel and its distribution network. This differentiates it from other global markets and justifies a unique approach for the CO2 emission reduction. This article describes a project with the main objective of optimizing the efficiency of Flex-Fuel engines running on ethanol, without deteriorating their performance with gasoline. The influence of the geometric compression ratio, the airflow structure and the inlet valve opening/closing strategy was investigated for fuel consumption and engine performance. The analysis of the experimental data confirmed the benefits of the compression ratio optimization on the combustion efficiency. Therefore, the development of efficient Flex-Fuel engines will lead to a sustainable route for mobility in Brazil.
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