Abstract: The hydrocarbon structures of seven kinds of base oils of heat transfer oils were characterized by mass spectrometry. The effect of the structures on the thermal stability of the base oils was tested. The results show that the thermal stability of the base oil of high temperature mineral type heat transfer oil is related to its hydrocarbon compositions. The thermal stability of naphthene is good, while that of paraffin and aromatics is poor. Moreover the deterioration rate of the base oil has a quantitative relationship with hydrocarbon compositions, which can better guide the selection of base oil for high temperature heat transfer oil.

Key words: mineral type heat transfer oil, base oil, thermal stability, hydrocarbon composition