maximum measured dimension difference is of ±9 μm which may be attributed to manufacturing tolerances and measuring errors.

4.3.4 Fuels

Three kind of fuels have been used in the experiments; these were standard automotive diesel fuel (ADF), n-heptane (NH), and mixture of n-hexadecane and heptamethylnonane (CN65). The CN65 fuel was obtained by mixing 59% n-hexadecane and 41% heptamethylnonane (by volume). The fuel tank of the experimental setup was emptied and the remained fuel in the connection pipes was drained after completing experiments with one kind of fuel. However, there are always some residuals inside the pipes, injector, and high-pressure pump. These remainder fuel quantities may change the tested fuel. Thus, the used fuels have to be tested after completing the experiments in order to get real fuel properties.

The properties of fuels are presented in Table 4.3.4.1. Cetane index was calculated from empirical equation given in ASTM standard D 4737. This equation include T10, T50 and T90 distillation temperatures and density as variables. The distillation temperatures of the fuels were obtained from TANAKA AD6-Auto Distillation Tester. The other test equipments are presented in Table 4.3.4.1.

Table 4.3.4.1: Fuel