In this study, first a new method has been presented for equalization of ambient conditions in different experiments on cooling towers. Next, using this method, the effect of four nanofluids including Zinc Oxide/Water, Silica/Water, Alumina/Water, and Graphene/Water has been investigated experimentally on the thermal performance of a wet cooling tower with a cross flow. The nanofluids have been studied at concentrations of 0.02, 0.05, and 0.08 wt% and the parameters of cooling range, effectiveness of the cooling tower, evaporation rate, the cooling tower characteristic, and volumetric heat transfer coefficient have been calculated and compared with each other. The different behavior of these nanofluids on the thermal performance of the cooling tower has also been indicated. For example, with the use of Graphene/Water at 0.02 wt%, the effectiveness and cooling tower characteristic have increased by 8.3% and 36%, respectively in comparison with pure water. On the other hand, with the use of Alumina/Water nanofluid across all the concentrations, the thermal performance of the cooling tower has weakened in comparison with pure water, and for example at 0.08 wt% of this nanofluid, the cooling tower characteristic has diminished by 14.7% in relation with pure water. Furthermore, by comparing the investigated nanofluids, it was found that Graphene/Water has resulted the best thermal performance in the cooling tower across all the concentrations, when compared with other investigated nanofluids. Moreover, the best thermal performance of the cooling tower by Graphene/Water has been obtained at 0.02 wt%, at which the volumetric heat transfer coefficient has increased by 36.2%, in comparison with pure water.

Keywords