This work experimentally investigates the combustion characteristics of refined soya, sunflower, and rapeseed
vegetable oils and, by means of statistical techniques, determines the optimal operating factors of an emulsion burner to obtain
the best combustion performance and low pollutant emissions. Given the high dimensionality of the study, principal component
analysis provides a descriptive study of the variables involved in the combustion process and of the physicochemical properties
of the vegetable oils so as to establish the correlations between them. ANOVA was then performed to identify which factors
(type of vegetable oil, fuel flow, and airflow), as well as any possible interactions, have the greatest impact on the combustion
results (performance as well as CO2, CO, NOx, CxHy, and SOx emissions). The ANOVA results showed that almost all of the
factors and their interactions were significant, which makes it essential to analyze the interaction plots in order to see the
optimal combinations of levels. This study showed that fuel flow rate was quite an important factor affecting combustion
characteristics, that the type of vegetable oil influenced CxHy emissions, and that the airflow rate displayed no clear trend.
Furthermore, the best combustion performance coupled with pollutant emissions below the lowest limits established by the
current legislation were achieved for a combination of maximum fuel flow and minimum airflow rates, with soya exhibiting the
best performance. In general, good combustion performances were obtained with extremely low NOx emissions. SOx emissions
were not detected in any of the combustion experiments performed.
