Thermal conductivity of ammonia + water mixtures over a wide range of concentrations

The thermal conductivity of NH3 + H2O mixtures (with 0.1–0.5 mass fraction ammonia) was measured at temperatures between 293.15 K and 313.15 K using a transient hot-wire apparatus. The apparatus and method were validated by comparing the measured values of the thermal conductivity of pure water and water + lithium nitrate mixtures with published values. Uncertainty in the measurements was estimated to be less than 0.017 W m−1 K−1. The thermal conductivities of NH3 + H2O mixtures were compared with the literature values and also fitted with several well-known models.

► A transient hot-wire apparatus was designed and set up, and was validated with pure water and water + lithium nitrate. ► Thermal conductivity of ammonia–water, between 293.15 K and 313.15 K and 0.1–0.5 ammonia mass fraction, has been measured. ► Measured thermal conductivities of ammonia–water mixtures were compared with literature values. ► The experimental data were fitted to two well-known models and both models are able to correlate the data equally well.