Model for thermal conductivity of CNT-nanofluids

Abstract

This work presents a simple model for predicting the thermal conductivity of carbon nanotube (CNT) nanofluids. Effects due to the high thermal conductivity of CNTs and the percolation of heat through it are considered to be the most important reasons for their anomalously high thermal conductivity enhancement. A new approach is taken for the modeling, the novelty of which lies in the prediction of the thermal behaviour of oil based as well as water based CNT nanofluids, which are quite different from each other in thermal characteristics. The model is found to correctly predict the trends observed in experimental data for different combinations of CNT nanofluids with varying concentrations.

Effects of uncertainties of conductivity models on mixed convection for Al2O3-water nano fluid

“…At Ri = 0:1, for all the ve used thermal conductivity models, as the nanoparticles volume fraction increases, the average Nusselt number increases. Moreover, as it can be observed from Figure 9, the Patel et al model [20] predicts minimum value for the average Nusselt number of the hot wall than average Nusselt number predicted by other employed thermal conductivity models. Furthermore, both the Corcione and Maxwell models estimate the average Nusselt number with an approximately same trend.…”

“…Besides, the Patel et al model [20] has been extensively used by researchers, too. This model is expressed as:…”

“…where c is constant and given as 25000, as determined by Patel et al [20]. A p =A f and Pe are de ned as:…”

“…Corcione [19] also investigated the e ects of di erent parameters on the properties of nano uids and introduced two empirical correlations to predict the e ective thermal conductivity and dynamic viscosity of various nano uids. In addition to the above authors, Patel et al [20] presented a correlation in order to calculate the e ective thermal conductivity. Recently, aside from the above investigation, there has been some theoretical research emerged to model the nano uid properties.…”

“…For example, Talebi et al [32] conducted a numerical study to investigate mixed convection ow and heat transfer of copper-water nano uid in a square lid-driven enclosure. They used the Patel et al model [20] and Brinkman model [14] to calculate the e ective thermal conductivity and viscosity of nano uid, respectively. Their results showed that at a given Reynolds number, the average Nusselt number increases with increase in the nanoparticles volume fractions.…”