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. Also, it was observed that the total amount of ice formed around the nozzle weighed at about 100mg∼260mg for 10 minutes after injection. Some fuel species were found in the ice attached on the front side of a nozzle, while frozen ice attached on the rear of a nozzle was mostly consisted of moisture of inlet air. Therefore, some frozen ice deposit, detached from front nozzle of an injector, may cause a problem of unfavorable air fuel ratio control in an LPLi engine.