Fuel Economy and Emissions of Philippine CME-Diesel Blends From Drive Cycle and Steady Speed Operation

This paper presents a study on the effects of transient and steady-state vehicle operation on fuel economy and emissions trends of an in-use Euro 2 Asian utility vehicle in the Philippines, with a normally aspirated direct-injection engine, and fueled with different CME-diesel blends designated as B1, B2, B3, B5, B10, B20, B50, & B100 corresponding to increasing CME percentage blends. The vehicle was driven on a chassis dynamometer following the Japanese 10-15 Mode drive cycle and at steady speeds of 40, 60, & 80 kph for fuel consumption and CO, NOx, and THC measurements. PM measurements were not undertaken. Drive cycle results showed that adding CME up to 20% by volume (B20) has a small effect on the heating values, specific fuel consumption (SFC), fuel economy (FE), and maximum power. Relative to neat diesel, the increase in SFC, lower FE and power beyond B20 were attributed to lower heating values at higher blends. CO was practically constant while THC and NOx generally decreased with increasing CME blends. The CO and THC trends were ascribed to overall lean mixtures and increased amount of oxygenated fuel at higher CME blends. B20 yielded the most emissions reduction without performance loss. Steady speed results indicated for all blends, SFC increased with vehicle speed due to higher road load. Above B10, SFC went beyond 5% higher than that for neat diesel and is attributed to lowered heating values of higher blends. The SFC of blends up to B10 approached that of neat diesel as speed increased suggesting more diesel-like combustion characteristics. The blend fuel economy showed an inverse relationship to SFC as expected. Both CO and NOx exhibited slightly decreasing trends with higher blends at all speeds. For a given blend, CO decreased while NOx increased as speed went higher. THC followed bowl-shaped trendlines with blend ratio. THC was high for neat diesel going lowest at B5-B10 and upwards again beyond B10. For a given blend, THC emissions decreased with increasing vehicle speed.