A novel semi-empirical model on predicting the thermal conductivity of diathermic oil-based nanofluid for solar thermal application. (August 2019)

• Record Type: Journal Article
• Authors: Li, Meng-Jie; Li, Ming-Jia; He, Ya-Ling; Tao, Wen-Quan
• Is Part Of: International journal of heat and mass transfer. Volume 138(2019)
• Page Start: 1002
• Page End: 1013
• Publication Date: 2019-08
• Subjects: Nanofluid -- Thermal conductivity -- Nanolayer -- Semi-empirical model -- Oil-based nanofluid -- Heat transfer fluid; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2019.04.080
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: A novel nonlinear thermal conductivity distribution in the nanolayer is proposed. Effects on nanolayer thickness of diathermic oil-based nanofluid are analyzed. A semi-empirical model of the nanofluid thermal conductivity is developed. The semi-empirical model is validated by lots of experimental data from literatures. Abstract: In this paper, a novel semi-empirical model is developed for predicting the thermal conductivity of Diathermic Oil (DO)-based nanofluid for solar thermal application. First, a corrected thermal conductivity model of nanofluid is developed based on the widely used Yu-Choi model. In this corrected model, the thermal conductivity distribution of nanolayer is treated as a quadratic form instead of a constant value along with the distance from nanoparticle. The corrected model shows the predicted thermal conductivity of nanofluid is significantly influenced by nanolayer thickness. Then, the semi-analytical nanolayer thicknesses for different DO-based nanofluid are calculated utilizing the corrected model and the experimental data in literatures. It is found that the nanolayer thickness of DO-based nanofluid is not a constant value but varies with the volume fraction of nanoparticles, nanoparticle radius, and nanofluid temperature. According to the semi-analytical results, the empirical equations between the above variables and nanolayer thickness are summarized. Finally, by adopting the empirical equation of the nanolayer thickness in the corrected model, a novel semi-empirical thermal conductivity model is developed for predicting the thermal conductivity of DO-based nanofluid. The semi-empirical thermal conductivity model is validated by a large number of experimental data from literatures.