The composition and properties of fuels listed in the ECN database are given in the tables below. Table 2.5.1 shows three oxygenated fuels (T70, GE80, and BM88) and five hydrocarbon fuels (NHPT, CET, HMN, CN80 and D2). T70 was originally used as a low-sooting fuel with a similar ignition delay as a cetane number 42.5 diesel reference fuel in order to facilitate optical diagnostics in the Sandia/Cummins optical engine (Dec, 1997). Similarly, the oxygenated fuels GE80 and BM88 had the same ignition delay as CN80 (cetane number 80) (Mueller, 2003). Ignition delays were matched only after adding a significant portion of an ignition enhancer, EHN, to BM88.

The fuel temperature (T_f) and density (ρ_f) at the fuel injector orifice are included in Table 2.5.1. Note that experiments were conducted at two fuel temperatures for D2 and CN80. This is because a fuel injector cooler was added after the initial D2 tests were completed. Table 2.5.1 shows that fuel density tends to decrease as temperature increases and that the fuel density of CN80 at 373 K is actually closer to the fuel density of D2 at 436 K. The fuel density can be important because fuel jets with the similar fuel density and pressure drop across the orifice will have similar jet momentum, which ultimately affects the mixing of the fuel jet. However, the fuel temperature difference had little effect on the soot level and location, or on the lift-off length and ignition delay (Pickett, 2003).