Evaporation characteristics of a palm methyl ester droplet at high ambient temperatures

Abstract

To investigate the evaporation characteristics of a palm methyl ester (PME) droplet at high ambient temperatures, droplet evaporation experiments were conducted. Thermogravimetric and differential thermal analyses (TG–DTA) were also conducted to investigate the presence of exothermic reactions during fuel evaporation. The results for PME were compared with those for diesel fuel and n-hexadecane. The results show that the initial heating period decreases and the average evaporation coefficient increases with increasing ambient temperature for all fuels. As a results, the droplet lifetime decreases with increasing ambient temperature for all fuels. It was found that the droplet lifetime of PME is longer than that of diesel fuel and n-hexadecane. The average evaporation coefficients of PME and diesel fuel are almost equal. The longer initial heating period of PME due to the higher boiling points of the components leads to the longer droplet lifetime. It was also found that exothermic reactions occur during PME droplet evaporation. The exothermic reactions are considered to be polymerization reactions of the unsaturated fatty acid methyl esters. The volume of the residue formed by the polymerization reactions decreases with increasing ambient temperature due to the shorter reaction time before complete evaporation.