抄録
With regard to global warming, the reduction of carbon dioxide (CO2) emissions is a problem of great urgency. Since the thermal efficiency of a marine diesel engine is high, it is difficult to reduce CO2 emissions simply by the improvement of its thermal efficiency. For this reason, it is realistic to limit the use of fossil fuels by using bio-fuels (raw vegetable oil, waste cooking oil) as a countermeasure against global warming. The aim of this study is to develop basic technology for the clean and safe use of bio-fuels (raw vegetable oil, waste cooking oil) and blended fuels of bio-fuel and heavy oil for marine diesel engines. In this paper, the emission characteristics of a 4 stroke cycle, medium speed marine diesel engine using gas oil, marine diesel fuel (MDF), and raw rapeseed oil were investigated. The findings are as follows: (1) The CO emissions and smoke of rapeseed oil were lower than that of gas oil or MDF at high load conditions (75, 100% load), but these were higher at low load conditions (25% load). (2) Compared to that of gas oil or MDF, the NOx emissions of rapeseed oil were higher at high load conditions and lower at low load conditions.
