Compression Ratio and Intake Air Temperature Effect on the Fuel Flexibility of Compression Ignition Engine
The effect of compression ratio and intake air temperature on the combustion characteristics of fuels with different octane ratings were investigated on a single-cylinder heavy-duty engine. The study examined Primary Reference Fuels (PRFs) and commercial grade diesel with octane numbers that range from 0 to 100. The engine was configured at a lower compression ratio (CR) of 11.5:1 than typical heavy-duty CI engines to compare the fuels’ burning regime with recently reported measurements at CR17:1. Experiments were performed at different intake air temperature of 20 to 80 DegC, intake air pressure of 1.5 to 3 bar absolute, net indicated mean effective pressure (IMEPNet) of 5 to 20 bar, air/fuel equivalence ratio (lambda) of 1.7 to 3.5, and fuel injection pressure of 700 to 1400 bar. The injection rates have been characterized to determine the hydraulic delay of the injector and thus define the actual ignition delay time.