Ather A. Quader

How Injector, Engine, and Fuel variables Impact Smoke and Hydrocarbon Emissions with Port Fuel Injection

Statistically designed experiments with a port fuel injected, single-cylinder engine were run to determine the effects of injector-, engine-, and fuel-related variables on exhaust smoke and hydrocarbon (HC) emissions. Among injector-related variables, targeting the fuel spray at the inlet valve centerline toward the valve head resulted in low smoke and HC emissions

“Wetting” the Appetite of Spark Ignition Engines for Lean Combustion

Single-cylinder spark ignition engine experiments conducted at constant speed, fixed airflow, and using isooctane as the fuel, demonstrated the effects of fuel-air mixture preparation on lean operation. Mixture preparation was changed by varying the time of fuel injection in the induction manifold, near the intake valve port. For comparison, a prevaporized fuel-air mixture was also investigated. Emphasis was placed on determining the effects of mixture preparation on combustion characteristics. Based on the results from this study, the often favored prevaporized mixture of fuel and air may not be the best diet for lean engine operation.

Conversion of Fuel Nitrogen to NO in Automotive Engines

Nitrogen-free and nitrogen-doped fuels were investigated using a single-cylinder, spark-ignition engine, and gasoline and diesel-powered vehicles. The single-cylinder engine experiments showed that only NO (nitric oxide) emissions were affected by nitrogen in the fuel and that the percentage of fuel nitrogen converted to NO (PNCNO) ranged from about 5 to 100. Generally, PNCNO increased when equivalence ratio, concentration of nitrogen in the fuel, engine load, or compression ratio decreased; PNCNO also increased as the level of EGR or engine speed increased, or as spark timing was retarded from MBT. The vehicle experiments showed PNCNO to be substantially higher (about 80-90) in gasoline engines than in a diesel engine (about 35), and that equivalence ratio, fuel-nitrogen concentration and EGR affected PNCNO in a multi-cylinder gasoline engine in the same manner as in the single-cylinder engine. The above experimental results could be rationalized on the basis of a speculative mechanism which incorporated the fuel-nitrogen reactions, the Zeldovich reactions and their interactions.