Thermodynamics and Transport Properties

The fundamentals of thermodynamics are reviewed, focusing on the chemistry of high-temperature metals, oxides (slags), and salts. Thermochemical data are provided for important molten metals: the free energies of solution of alloy elements, and interaction coefficients. Standard free energies of reactions are also provided, so the reader may calculate important chemical equilibria. Example calculations are provided for the deoxidation of steel. The removal of sulfur and phosphorus are also described. The second half of the chapter considers fundamental aspects of important physical properties: viscosity, surface tension, diffusion, and thermal and electrical conductivity.

NPG–TRIS Thermal Storage System. Quantification of the Limiting Processes: Sublimation and Water’s Adsorption

The NPG–TRIS binary system (NPG = (CH3)2C(CH2OH)2 = 2,2-dimetyl-1,3-propanodiol; TRIS = NH2C(CH2OH)3 = 2-Amino-2-(hydroxymethyl)-1,3-propanediol) was intensively investigated as a thermal energy storage system, due to the reversibility of its phase transitions and their associated energy. An adapted methodology was applied to precisely quantify its sublimation tendency. Relevant thermochemical data were revisited and evaluated using some specific experimental procedures. We also determined that the widely accepted requirement of working in an inert atmosphere to avoid deviations due to hygroscopicity is not necessary. Nevertheless, to take advantage of the energetic properties of the NPG–TRIS system, closed containers will be required to avoid NPG losses, due to its quantitatively determined high sublimation tendency.