Thermal performances and stabilities of nanofluids in an electrical oil heater

In this study, different nanofluids synthesized with aluminium oxide (alumina) and titanium dioxide in mass ratios of 1%, 3%, and 5% were tested in an electric oil radiator heater. The base fluid is heat transfer oil, and the nanofluids were synthesized using the two-step method. Simultaneously, optimum ultrasonic mixing times and surfactant amounts were determined to increase the nanofluids’ stability values. The stability of the nanofluids produced with alumina and titanium dioxide in mass ratios of 1%, 3%, and 5% was determined by using the sedimentation method. Among the alumina and titanium dioxide nanofluids whose thermal properties were measured, the nanofluids with the highest stability and the best thermal properties were used in heating experiments. The highest thermal improvement rates were 6% for alumina nanofluid and about 9% for titanium dioxide nanofluid, in the 5% mass ratio of nanoparticles. The temperature differences of the alumina and titanium dioxide nanofluids with respect to the base fluid were highest in the first region, at 8% and 10%, respectively, while the highest 11% and 27% temperature differences in the second region were measured, respectively. The stability values of the nanofluids in which significant increases in thermal values were obtained were maintained for long periods. It has been shown that nanofluids can be used in an industrial device.