Abstract
With regard to global warming, efforts toward the reduction of carbon dioxide(CO2) emissions need to be undertaken with great urgency. It is difficult to reduce CO2 emissions with further improvement of the thermal efficiency since the diesel engine’s thermal efficiency is already high. For this reason, it is realistic to restrain the use of fossil fuels by using bio-fuels (raw vegetable oil, waste cooking oil) as a countermeasure against global warming. In this paper, the authors studied the emission characteristics of a high speed, naturally aspirated, 4 stroke cycle diesel engine using gas oil, marine diesel oil(MDO), raw rapeseed oil, raw palm oil and waste cooking oil. The effect of fuel injection control on bio-fuel combustion using an assist injection system: new fuel injection system composed of a common rail system and a cam drive pump was also investigated. The findings are the following: (1) CO emission of bio-fuels is higher than that of gas oil or MDO. (2) Smoke from bio-fuels is lower than that of gas oil or MDO. (3) Assist injection system is effective to improve bio-fuel combustion by suppressing the maximum cylinder pressure and rapid premixed combustion.
