Characteristics of Gas-Dessolved Diesel Fuel Spray : Spray Characteristics and Simulating Flash Boiling Process

A new injection system using mixed fuel dissolved with liquefied CO_2 is proposed in this paper. Liquefied CO_2 is mixed with n-Tridecane under pressure in order to promote spray atomization and evaporation due to the effect of the flash boiling phenomenon during fuel injection, and to control the combustion process due to the effect of the internal exhaust gas recirculation (EGR) effct of CO_2 gas. Therefore, a simultaneous recduction of soot and NO_x is achieved effectively using this injection system. In this study, the characteristics of diesel fuel spray dissolved with liquefied CO_2 are investigated quantitatively by several optical measurements. The spray characteristics are revealed by analyzing the chemical thermodynamics. As a result, it is determined that atomization of this fuel is promoted by flash boiling much more than in n-Tridecane, which is normal reference fuel, and the spray structure is considerably different from that of the normal fuel. Moreover, the numerical analysis of atomization and vaporization processes are carried out, based on the flash boiling spray model.