A comprehensive experimental investigation of thermal conductivity of a ternary hybrid nanofluid containing MWCNTs- titania-zinc oxide/water-ethylene glycol (80:20) as well as binary and mono nanofluids

In this study, the thermal conductivity (k(nf)) of a ternary hybrid nanofluid containing Multi-walled Carbon Nanotubes (MWCNTs) - titania-zinc oxide/water-ethylene glycol (EG) (80:20) as well as binary and mono nanofluids has been studied. The nanofluid fabrication was performed by the two-step method by dispersing the nanoparticles in the base fluid using ultrasonic waves. The volume fractions of ternary hybrid nanofluids were phi= 0.1 % to 0.4 %, and mono and binary hybrid nanofluids were fabricated in phi= 0.1 % and phi= 0.4 %, respectively. After ensuring the stability of the nanofluids, the k(nf) was measured by the transient hot-wire method at a temperature range of T = 25-50 degrees C. The experimental results show that with increasing the temperature, the k(nf) also increases. Also, increasing the phi increases the k(nf). At higher phi, the effect of increasing temperature is even more evident. According to the results, the highest increase in k(nf) containing MWCNTs/water-EG was observed at a phi= 0.4 % and T = 50 degrees C, which showed an increase of 17.82 % compared to the base fluid. Finally, a mathematical model was proposed as a function of temperature and phi to estimate the k(nf) of a ternary hybrid nanofluid. A comparison of the results of the proposed mathematical model with the experimental results showed that the proposed model is highly accurate.