Chose language:    

Combustion of Lean LPG-Air Mixture




The long term aim of our research on "clean vehicle" is reducing pollution emission of in-used motorcycles in Vietnamto limits between EURO III and EURO IV standards.
The project is carried out by two stages:
1. Utilization of LPG on motorcycles
2. Application of catalyst converter for post treatment on LPG motorcycles
The present paper focuses on the first stage of the project. For this purpose, experimental an study of combustion LPG-air mixture has been carried out on experimental engines. The result shows that this mixture can be burnt with very low equivalent ratio. The specific fuel consumption is reduced considerably at this limit. This is an important advantage of gas fuel for vehicles running in urban conditions.
For applying the result, a new bi-fuel system (LPG/Gasoline) has been studied and manufactured for adapting LPG on original gasoline motorcycles which are Iargely used actually in Vietnam. In the system, the LPG in gaseous state at 30mbar is used, no evaporator is needed and the mixture fraction at any regime of engine is controlled by a throttling valve and depression in admission manifold. The gas throttling can be made manually or automatically which allows the motorcycle to run with lean mixture at low load regime. The installation of new fuel system doesn't cause any change of the structure andoutside view of the original motorcycle.
In case of necessity, the LPG/Gasoline motorcycle can be easily changed to run on gasoline by turning the fuel valve to gasoline position. Thus, this is comfortable for the users in the first step while the LPG supplying network is not largely installed.
The motorcycle running on LPG with the proposal fuel system has an emission reduction of about 80% of CO, NOx concentrations and about 60% of HC concentration in comparison with original gasoline running. The durability of LPG motorcycles is better than that of gasoline ones since the gas doesn't wash away the lubrication film. The fuel consumption is tested with 50cc, 100cc and 110cc motorcycles. With 1kg LPG they can run from 90 to 120km depending on road conditions.
Application of LPG on motorcycles is thus an appropriate way to reduce pollution emission and fuel consumption for transport in Vietnam.