Engine blow-by with oxygenated fuels: A comparative study into cold and hot start operation

T{(NPI), 1999 #117}his research compares the effects of oxygenated fuels on engine blow-by during engine cold and hot start operation using a common rail, turbocharged diesel engine. Diesel, waste cooking biodiesel and a highly oxygenated additive, triacetin, were used to make a range of fuel oxygen contents (0-13.57%). This study investigated engine blow-by and its correlation with indicated, brake and friction power; and blow-by normalised by different parameters. Result showed that neat diesel produces higher blow-by during cold start than the oxygenated fuels. There was a strong correlation between blow-by and indicated power, and the fuel calorific value was identified as a leading factor. To further analyse the results, this study normalised the engine blow-by by power to reveal the other influences on engine blow-by. The result verified the strong influence of power. This study also furthered the analysis by normalising the blow-by data by exhaust flow rate, intake air flow rate and injected fuel flow rate. It was discovered that oxygenated fuels perform better between hot and cold start, when compared to diesel. The blow-by inhibited properties of oxygenated fuels, such as higher lubricity and viscosity may be the cause for better performance of oxygenated fuels during cold start.