An investigation of thermal conductivity dependence of hybrid nanofluids containing carbon nanotubes on temperature and time

In this work, 50% deionized water and 50% ethylene glycol hybrid nanofluids containing carbon nanotubes (CNTs) with different lengths and 0.1 Vol% concentration were prepared and their thermal conductivity were measured at 30, 50, 70 and 90 °C. In order to change the CNTs lengths and enhance their dispersibility in different fluids, the CNTs were functionalized. The results showed that the thermal conductivity of nanofluids containing functionalized CNTs was higher than that of for nanofluids containing pristine CNTs. The results showed that such nanofluids exhibited a combination behavior of the pure deionized water based nanofluids and ethylene glycol based nanofluids. It was found that the thermal conductivity was increased with increasing temperature as pure deionized water based nanofluids, and the thermal conductivity was increased with increasing time for all kind of nanofluids as the ethylene glycol based nanofluids so that after 65 days, about 21% thermal conductivity enhancement was measured.