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The use of clean gaseous fuel in automotive engines has been continuously increased in order to meet the reinforcing emission regulations and to efficiently utilize limited natural resources. Since the liquid phase LPG injection (LPLI) system has an advantage of higher power and lower emission characteristics than the mixer type fuel supply system, many studies and applications have been conducted. However, the heat extraction, due to the evaporation of liquid LPG fuel, causes not only a dropping of LPG fuel but also icing phenomenon that is a frost of moisture in the air around the nozzle tip. Because both lead to a difficulty in the control of accurate air fuel ratio, it can result in poor engine performance and a large amount of HC emissions. The main objective of this study is to examine the characteristics of icing phenomenon and also aims to improve it through the use of anti-icing injection tip. An experimental investigation was carried out on the bench test rig in this study.

A liquid phase LPG injection (LPLi) system has been considered as one of the next generation fuel supply system, since it has a very strong potential to accomplish the higher power, higher efficiency, and lower emission characteristics than the mixer type that is classified as a second generation technology, whereas the LPLi system is classified as a third generation technology. However, when a liquid LPG fuel is injected into the inlet duct of an engine, a large quantity of heat is extracted due to its high latent heat of evaporation. This leads the moisture in the air to freeze around the nozzle exit, which is called icing phenomenon. It may cause damage to the outlet nozzle of an injector or inlet valve seat. In this work, the experimental investigation of the icing phenomenon was carried out. The results showed that humidity of air rather than the temperature of air in the inlet duct mainly controlled the icing process.