The normalized CO emissions measured as function of the fuel
injection temperature are shown in Fig. A.14. Emissions are
reduced by increasing the temperature, as was seen in case of diesel
and vegetable oil combustion (see Figs. 8 and 11). However, the
effect diminishes until no further reduction in CO level can be
observed around a temperature of 60 C. At this temperature, the
viscosity of biodiesel is approximately 2 cP. The result confirms
the trend for diesel shown in Fig. 8 above 40 C. In that temperature
region, corresponding to viscosities below 2 cP, the effect of
injection temperature is negligible as well