汽车专业翻译p001360 学位论文.doc

INTRODUCTION Most of the oil daily extracted is consumed in transportation (approximately 66.6% in America). Of the energy used in this sector, approximately 65% is consumed by gasoline-powered vehicles. Diesel-powered transport (trains, merchant ships, heavy trucks, etc.) consumes about 20%, and air traffic consumes most of the remaining 15%. In Italy, civil mobility accounts for about 74% of total consumption, half of which corresponding to about 30% of the national total consumption on transportation, inside urban and suburban zones. In these environment therefore, car emissions represents the main pollution source. Hydrogen cars, by eliminating CO2 emissions, could drastically reduce in short times pollution, especially in our living areas. The main obstacle, hindering the introduction into the market of hydrogen cars, is represented by the low efficiency of hydrogen storage system. Figure 1. Energy density, both volumetric and gravimetric, of various systems for hydrogen storage. The 2010 and 2015 DOE targets correspond to 6.0 and 9.0 % wt. We can assume that a fuel cell equipped car would run about 100 km per kg of hydrogen burned. Consequently a standard of 400 km would be fulfilled by 4 kg of hydrogen. Fig.1 shows various storage systems dimensioned to deliver 4 kg of hydrogen. Among the different storage systems, the hydrolysis of hydride seems the best promising one (Fig.2) . The reaction can be represented as: 2 MeHn+ nH2O →Me2On +2nH2 (1) The hydride should necessarily be regenerated off-board. Among the different metal hydride NaBH4 shows a hydrogen content higher than 10 % wt. The high hydrogen content and the simplicity of synthesis makes the salt a perfect candidate to store hydrogen for mobile application. As a fuel NaBH4 is less flammable and less volatile than gasoline. It is relatively environmentally friendly because it will quickly degrade into inert salts when released into the environment. Figure 2. Weight percent of hydrogen