Different mass concentrations of ammonia-water TiO(2 )nanofluids are applied to AARS and undergo the alternating pressure and temperature conditions. Applied nanofluids are periodically sampled and the absorbance, thermal conductivity, viscosity and surface tension of them are measured. So that the influence of the alternating working conditions on the nanofluid properties can be figured out. Experimental results show that the absorbance of the nanofluids circling in solution cycle is still gradually decreased over time, but the absorbance declining rates of them are much slower than that of nanofluids resting outside the system (the absorbance of the circulated nanofluids is about 3.5 times than that of resting nanofluid after 140 h); the changes of the thermal conductivity and viscosity of the nanofluids are highly correlated with the change of the absorbance of the nanofluids; the surface tension is significantly reduced after the addition of the surfactant at the same mass concentration. (C) 2020 Published by Elsevier B.V.