Development of calorimetric methods for the characterization of different aqueous deicers

Abstract

Different aqueous deicers in the range of 20–50 mass% were investigated by calorimetric methods. A dynamic differential scanning calorimetry (DSC) procedure was developed to determine the thermal properties (freezing point, melting enthalpy) of aqueous brines. Phase change temperatures were characterized for the broad melting peak determining two specific temperatures: extremum peak temperature (Tpeak) and the temperature corresponding to the inflection point of heat flow curve, which represents the end of the phase change (Tend). Heating rates of 0.2, 0.5 and 1.0 °C min−1 were used to extrapolate the characteristic temperatures at zero heating rate. For each sample, at least three runs were performed to check the reproducibility. Thermal analyses were conducted with Setaram DSC and with Netzsch DSC. Additionally, the influence of different kinds of sample cells was compared. The results demonstrated that the developed calorimetric method is suitable for the characterization of aqueous deicers. Our studies confirmed that the enthalpy of fusion is appropriate to assess the performance of aqueous deicers. The extrapolated end temperatures at zero heating rate matched the literature values very well.