Stability of viscosity and thermal conductivity of ammonia-water nanofluids after heating.

To select the optimal ammonia-water nanofluids and apply them to ammonia water absorption refrigeration systems (AARS), this paper investigates the influence of heating on viscosity and thermal conductivity of ammonia-water nanofluids. Six types of nanofluids were double prepared by adding the nanoparticles and surfactants according to previous investigations. One group of them were heated to 70℃ for an hour，and then thermal properties were measured after cooled to near room temperature. The other group of nanofluids without heating were measured at the same time. Experimental results show that heating will increase viscosity of nanofluids to some extent. However, thermal conductivity will increase, too, so their performance will not decline sharply, it means that prepared nanofluids can be applied in AARS.