Thermal conductivity measurements of nanofluids. (January 2017)

• Record Type: Journal Article
• Authors: Pryazhnikov, M.I.; Minakov, A.V.; Rudyak, V.Ya.; Guzei, D.V.
• Is Part Of: International journal of heat and mass transfer. Volume 104(2017:Jan.)
• Page Start: 1275
• Page End: 1282
• Publication Date: 2017-01
• Subjects: Thermal conductivity coefficient -- Nanofluid -- Nanoparticles -- Hot-wire method; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2016.09.080
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: The experimental investigation of the thermal conductivity of nanofluids was carried out. The dependence of thermal conductivity from the concentration and nanoparticle size was studied. The dependence of thermal conductivity from the material of nanoparticle was analyzed. It was shown that the thermal conductivity increases with increasing density of material of nanoparticle. The dependence of thermal conductivity on the base fluid properties was analyzed. Abstract: The paper presents the results of systematic measurements of the thermal conductivity coefficient of nanofluids at room temperature. In total, more than fifty various nanofluids based on water, ethylene glycol, and engine oil containing particles of SiO2, Al2 O3, TiO2, ZrO2, CuO, and diamond were studied. The nanoparticles volume concentration ranged from 0.25 to 8% and the particles size ranged from 10 to 150 nm. It is shown that the thermal conductivity of nanofluids is not described by the classical theories (Maxwell's and so forth). The nanofluid thermal conductivity coefficient is a complicated function not only of the particle concentration, but also the particles size, their material, and type of base fluid. Measured thermal conductivity coefficients almost always exceed the values calculated by the Maxwell's formula, though nanofluids with sufficiently small particles may have thermal conductivity coefficients even lower than those predicted by the Maxwell theory. However, in all cases, the nanofluid thermal conductivity coefficient enhances with increasing particle size. It is convincingly shown that there is no direct correlation between the thermal conductivity of the nanoparticle material and the thermal conductivity of nanofluid containing these particles. The base liquid also significantly influences the effective thermal conductivity of the nanofluid. It has been confirmed that the lower the thermal conductivity of the base fluid, the higher the relative thermal conductivity coefficient of the nanofluid.