| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系碩士班 === 90 === The engine’s performance, fuel consumption rate, exhaust emissions, and noise are all related to the combustion process; thus, it is essential to understand the combustion phenomena inside the combustion chamber.
This research is done against a KIMCO APEX 125 cc single cylinder carburetor motorcycle gasoline engine. The engine’s volumetric efficiency can directly affect the engine’s output and the emission levels; thus, this research will modify the intake manifold system in order to understand the pipe boundary layer effects on the air’s resistance entering the engine and the engine performance. A good intake and/or exhaust manifolds’ design can result in good volumetric efficiency and/or lower back pressure. The back pressure in the exhaust pipe can severely affect the intake flow characteristics.
Results show that the carburetor gasoline engine has serious air/fuel ratio instability. The equivalence ratio varies from 0.7 ~ 1.5 which are completely out of design accuracy. The fuel consumption rate, the cylinder pressure, and the heat release rate are not varying reasonably according to various engine speed and load combinations. The exhaust emissions measurements are also not meaningful since the equivalence ratio may exceed 1.0 which indefinitely leads to sever incomplete combustion.
A further modification such as electronic control fuel injection system is suggested for the future research in order to provide the industry the technical information on how to design a better intake/exhaust manifold system.
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