تأثیر مقدار سوخت بیو الکل بر عملکرد یک موتور توربو شارژر و موتور شمع
Abstract
1- Introduction
2- Experimental setup
3- Results
4- Conclusions
References
Abstract
In this work, the behavior of an engine running with binary and ternary mixtures of n-butanol, ethanol and gasoline has been investigated. Analyses have been performed at different engine speed both at low load and at high load. For each blend, the air to fuel ratio has been kept stoichiometric, while the spark time has been tuned in order to maximize the engine brake torque and hence the engine fuel conversion efficiency. The performance, the combustion characteristics and the pollutant emissions of the engine fueled by biofuel mixtures have been compared to those characterizing the engine running with neat gasoline. In an attempt to provide a guideline for the development of engines running with every mix of gasoline and alcohol, measurements are presented as a function of the oxygen content of the fuel. When the fuel oxygen content increases, results show that the optimal spark time must be retarded at part load while must be advanced at high load. At this operation, the maximum obtainable efficiency increases, the CO2 specific emissions decrease almost linearly together with NOx and HC specific emissions, the engine torque remains practically the same, while the brake specific fuel consumption increases.
Introduction
Due to the increase of the economic activities and the wider use of vehicles especially in developing countries, the demand for transport fuels is increasing. On the other hand, stricter rules for the control of both pollutant and climate-altering emissions induce to improve the conventional fuel performance and to use alternative fuels in conventional internal combustion engines. From a technological point of view, downsizing, gasoline direct injection, variable valve timing and actuation, exhaust gas recirculation, variable compression ratio are some of the approaches aimed at improving the thermal efficiency of spark ignition engines. Some of these technologies, coupled to the usage of bio-fuels, could lead to significant reduction in CO2 emissions. Biofuels used in lieu of gasoline also reduce global CO2 emissions. Compared to pure gasoline, the massive use of bio-alcohol as a transportation fuel would save significant amounts of fossil fuels, while reducing greenhouse gas emissions by almost half. On the other hand, conventional gasoline engines are 20e30% less efficient than Diesel engines. Therefore, the need to improve the fuel economy of gasoline engines is a major challenge to meet future CO2 emission targets for passenger cars. For spark ignition engines, there is a wide range of biofuels alternative to gasoline. Today, ethanol and butanol are among the most discussed [1]. Bioethanol already contributes from 20 to 30% of the fuel market in the United States and Brazil due to its accessibility, low cost and compatibility with modern engines without modifications [2]. Biobutanol in its various isomeric structures can be used as a fuel for conventional engines. Today, it is considered to be of great interest since its physical properties are very similar to those of gasoline [3].