A desire to survey the effects of fuel composition and additives on the make-up and evolution of the deposits in a working EGR system required development of rapid procedures to both generate and characterise them. Thermogravimetric analysis (TGA) is here shown to be a very useful characterisation technique. It is most readily used on end-of-test samples yet is also capable of studying deposit evolution. Samples from the deposits, or fractions of these samples, after separation using Organic Geochemistry extraction techniques, may be examined. Deposit evolution was shown to be consistent with mechanisms proposed in the literature. Critically, comparison of test to ‘real-world’ deposits showed those generated rapidly in the laboratory to be representative of those generated over longer periods in vehicles on the road.

No abstract