فهرست نشریات علمی دسترسی آزاد ایران

In this study, the effect of the presence of a magnetic field (MF) on the thermal conductivity of the nanofluid (NF) ( ) containing spinel ferrite nanoparticles (NPs) (MFe 2 O 4 , M=Fe, Co) was investigated. CoFe 2 O 4 NPs were concentrated by the coprecipitation method. Both NPs were characterized by SEM, EDX, XRD, and VSM. The thermal conductivity was investigated and compared in the presence and absence of an MF. In addition to the intensity of MF (100, 200, 300, and 400 G), the effect of the concentration of NPs (from 0.25 to 2 Vol%) on  at a constant temperature of 25 °C was investigated. According to the results, in the absence of MF, the  of CoFe 2 O 4 /water ferrofluid (FF) was higher than that of Fe 3 O 4 /water FF in different concentrations. Furthermore, as the intensity of the MF increased, the  of both Fe 3 O 4 /water and CoFe 2 O 4 /water FFs increased. This increase was more observed for the FFs containing Fe 3 O 4 NPs. At the highest concentration (2 Vol%), with the increase of MF up to 400 G, the  of Fe 3 O 4 /water has increased by about 3.2%, while this increase was about 1.8% for CoFe 2 O 4 /water. Increasing the volume percentage of NPs also had a positive effect on the thermal conductivity coefficient. Finally, according to the obtained results, correlations were presented to predict the  of both FFs according to the intensity of the MF and the concentration of NPs. The proposed correlations had a satisfactory accuracy with R 2 values of 0.98 for both FFs.