Densities and Viscosities of Aqueous Alkaline Nitrate and Nitrite Solutions Used in Absorption Heat Pumps

Density and dynamic viscosity of four aqueous alkaline nitrate and nitrite solutions were measured experimentally. These considered solutions are used in developed absorption refrigeration cycles and heat pumps as binary working fluids (coolant/absorber). Experimentations used a vibrating-tube densimeter and piston-style viscosimeter for density and viscosity, respectively. The measurements were accomplished at atmospheric pressure. Two solutions (salts/water) were made of lithium nitrate, potassium nitrate, and sodium nitrate (LiNO 3 + KNO 3 + NaNO 3 ) in the mass ratios of 53:28:19 and 53:42:5. The other two solutions of salts with water were lithium nitrate, potassium nitrate, and sodium nitrite (LiNO 3 + KNO 3 + NaNO 2 ) in salt mass ratios of 53:35:12 and 60:36:4. These compositions were selected according to the best solubility. In the experimental study, the salt mass fraction was varied from 0.50 to 0.80. On the other hand, the temperature range adopted is from (323.15 to 403.15) K. Also some mathematical models were used to predict the values of the experimental values for comparison. The models resulted in very good agreement with the experimental results.