Experimental study on the effect of magnetic field on the heat conductivity and viscosity of ammonia–water

External magnetic field may enhance the ammonia absorption in ammonia–water absorption refrigeration system. In this paper, the variations of viscosity and heat conductivity of magnetized ammonia–water are studied experimentally. The measured ammonia–water is magnetized by an electromagnet with magnetizing intensity from 132.64 to 261.35 mT. Different magnetization times including 10, 20 and 30 min are adopted. Engler viscosity measurement and transient double hot-wires measurement are used in the measurement of viscosity and heat conductivity respectively. The results show that the viscosity of ammonia–water solution decreases after magnetization, the decrease in viscosity is greater when the magnetic field is stronger and the magnetization time is longer. The heat conductivity of ammonia–water solution after magnetization increases with the prolonging of magnetization time and the increase of magnetizing intensity. It is not helpful to increase the heat conductivity of ammonia–water by increasing the magnetizing intensity and magnetization time unlimitedly. In the present experimental conditions, when the magnetization current is 8 A and the magnetization time is 30 min, the increase of the heat conductivity reaches the maximum. The variations of the viscosity and heat conductivity of magnetized ammonia–water may be attributable to Lorentz force and hydrogen bond breaking in microstructure.

Research highlights▶ The viscosity of ammonia–water solution decreases after magnetization. ▶ The heat conductivity of ammonia–water solution increases after magnetization. ▶ Increasing the magnetizing intensity and magnetization time unlimitedly is not helpful.