MONITORING WAX CRYSTALLIZATION IN DIESEL USING DIFFERENTIAL SCANNING CALORIMETRY (DSC) AND MICROCALORIMETRY

The crystallisation of wax on cooling a diesel was monitored by DSC with cooling rates of 5-0.2-degrees-C/min and by a microcalorimeter with the lower rates of 0.1-0.01-degrees-C/min. The melting of crystallised wax was also monitored by DSC to assess the thermodynamic reversibility of the process. The results show that crystallisation temperatures from DSC at a cooling rate of 1-degrees-C/min are close to those from microcalorimetry at 0.01-degrees-C/min (a realistic cooling rate for diesel in a vehicle). A comparison of crystallisation and melting data shows that equilibrium crystallisation conditions are not achieved even at the lowest cooling rate used here.