Influence of cooling rate on the wax precipitation characteristic of waxy oil samples in DSC test

When the differential scanning calorimetry (DSC) is applied to investigate the wax precipitation process of crude oil, it can measure the parameters (e.g. wax precipitation point, and wax content) accurately and fast, with little oil consumption. The cooling rate in the DSC test affects degree of under cooling and instrument sensitivity in the process of wax precipitation, and thus brings impacts on the wax precipitation characteristic curve and the accuracy of test results. In this paper, the influence of cooling rate on the waxy oil samples in the DSC test was analyzed. It is shown that, with the increasing of cooling rate, the wax precipitation point tends to decrease linearly, and the wax content increases and then decreases. Finally, the causes of these phenomena were analyzed from the perspective of thermodynamics. It is confirmed that the appropriate cooling rate of waxy oil samples in the DSC test should be 5 ℃/min.