Heat capacities of the mixed-solvents desiccants (glycols + water + salts)

Heat capacities of glycol/H2O/salt systems have been measured over the temperature range 303.15–353.15 K with a differential scanning calorimeter. The salts studied were lithium chloride and lithium bromide; the glycols considered were diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol and dipropylene glycol. For each ternary system, four systems of which (4–25 mass%) salt mixed with various glycols (50–80 mass%) were studied. An extended Redlich-Kister-type binary system equation was used to correlate the measured heat capacity data. To this end, the heat capacities of pure glycols and aqueous glycol solutions were also measured. The correlations give satisfactory results as shown by an overall AAD for heat capacity calculations of 0.5% for 234 data points. The present measurements are, in general, of sufficient accuracy for most engineering-design calculations for the design of dehumidifier equipments.