Inorganic Salt Hydrates Research Articles

Thermodynamic evaluation of the intermolecular interactions of potassium fluoride crystal dihydrate in gas chromatography

Potassium fluoride crystal dihydrate is used as the stationary phase for the rapid analysis of polar compounds in aqueous solutions. KF·2H2O is compared with some conventional stationary phases, organic salts and molten crystal hydrates of inorganic salts.

Low temperature latent heat thermal energy storage: Heat storage materials

Heat-of-fusion storage materials for low temperature latent heat storage in the temperature range 0–120°C are reviewed. Organic and inorganic heat storage materials classified as paraffins, fatty acids, inorganic salt hydrates and eutectic compounds are considered. The melting and freezing behaviour of the various substances is investigated using the techniques of Thermal Analysis and Differential Scanning Calorimetry. The importance of thermal cycling tests for establishing the long-term stability of the storage materials is discussed. Finally, some data pertaining to the corrosion compatibility of heat-of-fusion substances with conventional materials of construction is presented.

Simultaneous differential scanning calorimetry and reflected light intensity measurement

A simple, cheap modification to a Perkin-Elmer differential scanning calorimeter DSC 1-B is described which enables simultaneous observation and recording of optical changes in the sample during the DSC run. The theoretical background to the reflected light technique is discussed, and the combined technique is shown to have little effect on the operation of the DSC. The need for direct observation of the nature of changes detectable by DSC is demonstrated by a wide variety of applications. Phase changes, liquid crystals, the dehydration and decomposition of inorganic salt hydrates, as well as the study of polymer transitions and decompositions are reported.

The Stability of Hydrates of Inorganic Salts in Cooling—Heating Cycles

AbstractThe stability of calcium chloride hexahydrate with an admixture of nucleating agent was tested during 1000 cooling—heating cycles and was found satisfactory. The experimental set‐up based on computer monitored heating and natural cooling in a cold room is described. Addition of lithium chloride decreases phase transition temperature, but affects the stability.

Salt hydrates as absorbents in heat pump cycles

A thermodynamic analysis has shown that inorganic salt hydrates are attractive candidates for absorbents in heat pump cycles. Their computed performance efficiencies compare favorably to those of previously proposed solid and liquid absorbents, under conditions typical of domestic, solar-powered, intermittent operation. It was found that hydrate cooling cycles, with coefficients-of-performance in the range of 0.6-0.7, can significantly outperform all others considered. In space heating applications, solid-absorbent cycles were far superior to a typical liquid-absorbent cycle in both overall efficiency and per cent of thermal energy input stored. Predicted hydrate coefficients-of-performance were in the range 1.4-1.6 with 75–85 per cent effective storage.

Thermal storage: Nucleation of melts of inorganic salt hydrates

AbstractThis paper reviews the heterogeneous nucleation of melts of some inorganic salt hydrates. Five salt hydrates were tested as materials for heat storage.

Differential thermal analysis of transitions in finely-divided solids suspended in liquid media

The experimental difficulties associated with differential thermal analysis (DTA) are reviewed. Quantitative work has always required calibration of the equipment, and conventional solid diluents have serious disadvantages. It is shown that calibration is not strictly necessary, given appropriate conditions. Dilute suspensions of polymer crystals in organic liquids provide ideal media for DTA when used as diluent and as reference material. Convection currents are suppressed and the medium can support fine particles of the solid under test, even when the solid has a relatively high specific gravity. The new theory and techniques have been tested experimentally by measuring the heats of fusion of two inorganic salt hydrates. The results are in excellent agreement with literature values. A novel arrangement with a double thermocouple junction is shown to have considerable potentialities as a means of making precise measurements quite simply.