AN INSTRUMENT FOR THE EXAMINATION OF NUCLEATION FROM SOLUTION AND ITS APPLICATION TO THE STUDY OF PRECIPITATION FROM DIESEL FUELS AND SOLUTIONS OF NORMAL-ALKANES

An automated apparatus has been designed and constructed to measure precipitation and dissolution of solids from solution at varying automatically predetermined rates of heating and cooling. The appearance and disappearance of crystals are detected by means of a fibre optic turbidity sensor attached to a Sybron/Brinkman colorimeter. Temperature is measured by a Pt resistance thermometer attached to a constant current source. Both of these measurements are recorded by a personal computer via an analog to digital converter. The temperature of the system and its variation is controlled from the personal computer via a digital to analog interface attached to the control head of a Haake F3Q cryostat. The system has been used for measurements of precipitation and dissolution temperatures for diesel waxes with and without nucleation additives. Studies have been made of the nucleation of a single n-alkane from solution. From these measurements, saturation curves, orders of reactions, interfacial tensions and the critical radii of nuclei can be assessed.