Drive Cycle Analysis of Butanol/Diesel Blends in a Light-Duty Vehicle

The potential exists to displace a portion of the petroleum diesel demand with butanol and positively impact engine-out particulate matter. As a preliminary investigation, 20% and 40% by volume blends of butanol with ultra low sulfur diesel fuel were operated in a 1999 Mercedes Benz C220 turbo diesel vehicle (Euro III compliant). Cold and hot start urban as well as highway drive cycle tests were performed for the two blends of butanol and compared to diesel fuel. In addition, 35 MPH and 55 MPH steady-state tests were conducted under varying road loads for the two fuel blends. Exhaust gas emissions, fuel consumption, and intake and exhaust temperatures were acquired for each test condition. Filter smoke numbers were also acquired during the steady-state tests.

The results showed that for the urban drive cycle, both total hydrocarbon (THC) and carbon monoxide (CO) emissions increased as larger quantities of butanol were added to the diesel fuel. Oxides of nitrogen (NO_x) were not significantly affected by the 20% butanol blend and decreased with the 40% butanol blend. Drivability of the vehicle decreased noticeably for the 40% butanol blend, especially for the cold-start urban drive cycle. Fuel consumption increased as the blend ratio of butanol increased, due primarily to the lower energy density of butanol compared to diesel. For the highway drive cycle, THC and CO emissions were not significantly impacted but NO_x showed a slight increase as the butanol blend ratio increased. For the steady-state tests, a reduction in filter smoke number with increasing butanol quantity was observed. An 80% reduction in filter smoke number was observed for the 40% butanol blend.