Thermodynamic Description of Aqueous Mixtures of New Antifreezes

High Resolution Image Download MS PowerPoint Slide Combustion engines for motor vehicles will still play a substantial role for many years further. As a consequence of the power increase leading to high local surface temperatures of up to 260 °C in a modern engine, the requirements on coolants regarding stability and ability to maintain the dissipation of heat are also increased. In search for possible alternatives to currently applied freezing point depressants (coolants) and to create an overview about antifreezes in use, thermodynamic properties, namely, freezing points, densities, viscosities, specific isobaric heat capacity, boiling point curve data, and osmotic coefficient values were measured, generalized, and systemized with interpolated data from the literature for aqueous solutions of four molecule classes studied in wide temperature (from −45 to 95 °C) and composition ranges and are given as a database. The nonaqueous components are diols: 1,2-propanediol and 1,3-butanediol; glycols: ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol; glycerols: glycerol and diglycerol; and carbonic acid salts: potassium acetate, sodium propionate, and potassium propionate. Conclusions have been drawn about the applicability of liquids with the best flow behavior and thermal properties as antifreezes, which fulfill the technical requirements but also those of sustainable chemistry including low toxicity, efficiency, and cheapness.