Comparative Investigation on Fuel Feed Methods in Two-Stroke Cycle Methanol Engine

A direct fuel-injection two-stroke cycle engine operated with neat methanol was investigated. The engine performance, combustion and exhaust-gas characteristics were analyzed experimentally and compared for operation with a carburetor, EFI injection at the intake manifold, and EFI injection at the scavenging port.

The power and the brake thermal efficiency of the direct fuel-injection engine were higher than those of engines operated with a carburetor and either of the two EFI methods.

The exhausted unburnt fuel of the direct fuel-injection engine was lower than that for operation with a carburetor, and formaldehyde and the CO concentration were of the same level as for operation with the carburetor and EFI methods. The NO_x concentration of the direct fuel-injection was half the level of the result of carburetor operation. Because a stratified charge using direct fuel-injection activated the combustion of the lean mixture which increases working gas temperature, therefore, the vaporization of injected fuel was promoted by the elevated temperature of the residual gas.