1.1.2. The Influence of Temperature on Nanofluid

The temperature may affect nanofluid thermal conductivity. Despite the fact that nanofluids can be used at different temperatures, few studies have examined the temperature effect on their thermal conductivity. Table 2 summarizes published studies on nanofluids in which thermal conductivity dependency on temperature. The nanofluids which comprise Al2O3 and CuO nanoparticles in water are used to measure the thermal conductivity which is investigated by Das et al. [42]. In their investigation, they employed a temperature oscillation technique to measure thermal diffusivity. They found that the thermal conductivity enhancement of these nanofluids increased by a factor of two to four over the temperature range of 21◦ to 51◦ Celsius. The different sizes of nanoparticles of Al2O3 dispersing in water to investigate the thermal conductivity of nanofluids are carried out by Chon and Kihm [43]. The nanoparticles ranged from 47 to 150 nanometers in size. They found that there was a slight increase in thermal conductivity in relation to temperature. When the temperature of the fluid was raised from 31 ◦C to 51 ◦C, there was a 6–11% increase in the thermal conductivity of nanofluids. It is interesting to note a little reduction in the thermal conductivity as the temperature increases, which is the opposite tendency seen in nanofluids containing spherical nanoparticles.

**Table 2.** The Influence of Temperature on Nanofluids.

