Effect of dispersion stability on thermal conductivity of binary nanofluids

Abstract

In order to apply nano-particles to the ammonia-water absorption refrigeration, TiN-ammonia water nanofluids (the binary nanofluids) were prepared by two steps. The dispersion stability of the binary nanofluids in different mass fractions of nano-particles and ammonia is investigated by the light absorbency ratio index methods. And the thermal conductivities were measured on the basis of the dispersion stability. The results show that the content of nano-particles and ammonia is the key parameters that affect the dispersion stability and thermal conductivity of nanofluids. The dispersion of nanofluids firstly increases to a maximum and then decreases with the increase of the content of nano-particles. It is the same with the increase of the ammonia content. The dispersion stability directly affects the thermal conductivity of binary nanofluids, and better dispersion can induce higher thermal conductivity. The nanofluid achieves the optimal dispersion stability and thermal conductivity ratio when the mass fraction of ammonia and nano-particles is 5% and 1.5% respectively.