Effects of engine parameters on performance and emission characteristics of a variable compression ratio engine

This study investigates the performance and emission characteristics of a variable compression engine which is fueled with alternative fuels such as biodiesel and diesel-biodiesel blends. Camelina Sativa (false flax) oil which has variety of usage and has a potential of being feedstock for biodiesel production were used as alternative fuel. Also various common oils such as sunflower and canola oil were used as feedstocks for biodiesel production. Experimental study was conducted with a four stroke, single cylinder, naturally aspirated, multi fuel variable compression ratio engine by using diesel and alternative fuels. Experiments were performed at 1500 rpm and under partial load condition with three different compression ratios. Theoretical study was performed with the aid of Diesel RK software. Technical specifications of test engine were modelled using Diesel RK software and performance and emission characteristics were evaluated and compared with experimental results. The study showed that, increasing compression ratio significantly improves thermal efficiency and specific fuel consumption of the engine for all test fuels. The engine emitted lower carbon monoxide emission but higher carbon dioxide and nitrogen oxides (NOx) emission when operated at higher compression ratios. Furthermore, biodiesel usage increased specific fuel consumption slightly. The engine emitted lower carbon monoxide emission but, higher nitrogen oxides (NOx) emissions when biodiesel used as fuel.