| Summary: | 碩士 === 國立中興大學 === 機械工程學系 === 87 === To use Liquid Petroleum Gas (LPG) as an alternative fuel is a excellent method to wildly utilize the world energy source.As the LPG vehicles have lower emissions than the gasoline vehicles,people who care about environment are concerned on this characteristic.This paper presents three major parts：The first is the discussions of the effects of LPG engine performance and emission.According to the results of our experiments,the throttle size of mixer strongly influences the engine performance.Based on the prosperity mixer,the LPG engine presents 6~7﹪power less than the gasoline engine power,Air-to-Fuel ratio strongly effects the emission,the total hydrocarbon and total OFP of the LPG emission is less than that of gasoline.Otherwise ,it is necessary to have an early spark angle on LPG engine,but the more early angle will cause the difficulty of engine start.
The second part is concerned on the HC components of the LPG emission,according to our analysis of emission samples,unburned LPG is an important part of the LPG HC emission.Using carbon numbers to compare with gosoline emission,we find that gosoline HC components distribute widely,but LPG emission components focus on low carbon number components.Ethylene and Propene present the major parts of the emission Ozone forming potential .
The third part is establishing the model of LPG engine fuel system,and compare with the real engine state.We find that fuel system has almost no effect on LPG system characteristics,A/F total delay is caused by the mixture manifold delay and the intake manifold delay.
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