Droplet vaporisation characteristics of vegetable oil derived biofuels at high temperatures

To characterise the mechanisms occurring in the deposit formation during th e combustion of vegetable oils used as biofuels in Diesel engines, it is ne cessary to investigate the vaporisation of vegetable oil droplets under var ious flow, pressure and temperature conditions. In the current work, experi mental results about the vaporisation of rapeseed and sunflower oil methyl ester droplets at high temperatures are presented. The fibre-suspended drop let technique is used and the time evolution of droplet diameter juring vap orisation is observed by imaging technique. Average and instantaneous vapor isation rates have been estimated from the d(2)-curves at temperatures betw een 473 and 1020 K and at atmospheric pressure. The droplets of vegetable o il methyl esters evaporate like mono-component droplets with a very signifi cant heating phase. A comparison with experimental results obtained with n- alkanes droplets (from n-pentane to n-decane) and prediction of the quasi-s teady theory is also presented and discussed. (C) 2000 Elsevier Science Inc . All rights reserved.