The effect of fuel viscosity on pollutant emissions is determined by adjusting the injection temperature.
The measurements confirm that a reduction in fuel viscosity improves the spray quality, resulting in
faster droplet evaporation and more complete combustion. CO emission levels were observed to decrease
linearly with viscosity in the tested range. For the pressure-swirl nozzle used in the tests, the upper
viscosity limit is found to be 9 cP. Above this value, droplet evaporation seems to be incomplete as the
exhaust gas contains a considerable amount of unburned fue