Experimental study of the thermal conductivity of ammonia + water refrigerant mixtures at temperatures from 278 K to 356 K and at pressures up to 20 MPa

The thermal conductivity of binary ammonia + water mixtures was measured over the temperature range from 278 K to 356 K and at pressures to 20 MPa using the steady-state hot-wire method. Measurements were made for ten compositions over the entire concentration range from 0 to 1 mole fraction of ammonia, namely, 0.0, 0.1905, 0.2683, 0.3002, 0.4990, 0.5030, 0.6704, 0.7832, 0.9178, and 1.0 mole fraction of ammonia. In total, 316 experimental data points were obtained. The expanded uncertainty, with a coverage factor of k = 2, of the thermal conductivity, pressure, temperature, and concentration measurements is estimated to be 3%, 0.05%, 0.02 K, and 0.0014%, respectively. The average absolute deviation (AAD) between the measured and calculated reference values for pure water and ammonia is 1.3% and 1.4%, respectively. Correlation models for the thermal conductivity of liquid ammonia + water mixtures were also developed.