Search

Abstract In past decades, nanofluid science has been widely investigated for thermal related activities. In thermal transport applications, thermal conductivity and dynamic viscosity are closely related to cooling system performance enhancement. The genuine anomaly behind thermal conductivity and dynamic viscosity enhancement in nanofluid is still undiscoverable. In this paper, comprehensive study on principle factor behind thermophysical property enhancement focusing on thermal conductivity and dynamic viscosity is conducted. Thus, a detailed review of existing experimental results for thermal conductivity and dynamic viscosity enhancement are compiled and discussed in this manuscript. Analytical tool approach such as fishbone diagram and summary tables are used to highlight principle factor for thermal conductivity and dynamic viscosity enhancement. The principal factor which influences the thermal conductivity is shape of the particle, nanofluid preparation, interfacial layer, Brownian motion, particle clustering and aggregation. Meanwhile, the principal factor influencing dynamic viscosity is the physical behavior of the particle, nanofluid preparation, particle clustering and aggregation. The optimum nanofluid should have high thermal conductivity and minimum viscosity. High thermal conductivity is mandatory for maximum heat absorption in thermal transport applications. Meanwhile, minimum viscosity ensures less pressure drop which reduces the power consumption and increases the overall efficiency of the system. [ABSTRACT FROM AUTHOR]

Abstract: The increasing demand of nanofluids in industrial applications has led to increased attention from many researchers. In this paper, heat transfer enhancement using TiO2 and SiO2 nanopowders suspended in pure water is presented. The test setup includes a car radiator, and the effects on heat transfer enhancement under the operating conditions are analyzed under laminar flow conditions. The volume flow rate, inlet temperature and nanofluid volume concentration are in the range of 2–8 LPM, 60–80°C and 1–2% respectively. The results showed that the Nusselt number increased with volume flow rate and slightly increased with inlet temperature and nanofluid volume concentration. The regression equation for input (volume flow rate, inlet temperature and nanofluid volume concentration) and response (Nusselt number) was found. The results of the analysis indicated that significant input parameters to enhance heat transfer with car radiator. These experimental results were found to be in good agreement with other researchers' data, with a deviation of only approximately 4%. [Copyright &y& Elsevier]

Abstract: The effects of the tube specifications on the heat transfer in car radiator are significant to improve cooling system performance. Friction factor and heat transfer enhancement of three types of nanofluids flow through horizontal three shapes of tubes has been evaluated numerically. CFD model by using FLUENT software depending on finite volume method was conducted. TiO2 nanoparticles with volume fractions (1%, 1.5%, 2% and 2.5%) are suspended in water as a base fluid to be nanofluids is used in this study. On the other hand, three types of tubes (circular, elliptical and flat tube) are chosen with 3mm hydraulic diameter and 500mm length. Numerical results show that the increase in volume fraction of nanofluid due to increase in fluid flow characteristics and heat transfer enhancement as compared with base fluid. The results of CFD model are compared with experimental data available in literature, and there is a good agreement with deviation 2%. [Copyright &y& Elsevier]

Molten salts are utilized in concentrated solar power (CSP) as a working fluid to store and transfer solar thermal energy. In this study, we attempted to enhance the thermal energy storage (TES) characteristics of the ternary nitrate molten salt of KNO 3 , NaNO 2 , and NaNO 3 , also known as HITEC molten salt, using cupric oxide (CuO) as additives for CSP applications. HITEC was doped with 0.1, 1, 3, and 5 wt% of CuO nanoparticles using the two-step wet method. Differential scanning calorimeter (DSC) was utilized to evaluate the specific heat capacity, melting point, and latent heat of the prepared material. Thermal stability was measured by thermogravimetric analysis (TGA) while the characterization analysis was performed using Fourier-Transform Infrared (FT-IR) spectroscopy, Field Emission Scanning Electron Microscope (FESEM), and Energy Dispersive X-ray Spectroscopy (EDS). The results showed that 0.1 wt% CuO nanoparticles is the optimum CuO nanoparticles concentration which resulted in a specific heat capacity enhancement of 5.6%, a 30% improvement of latent heat, and 9% enhancement of thermal stability. The morphological analysis revealed the formation of bright chain-like nanostructure due to nanoparticle dispersion, which may the possible reason for the thermophysical property enhancement. • CuO doped Nano-enhanced HITEC molten salt has been studied and presented. • Specific heat capacity enhanced by 5.6% at 0.1 wt% of CuO nanoparticles. • Latent heat enhanced by 30% at 0.1 wt% of CuO nanoparticles. • Developed NEMS has potential to improve overall efficiency of CSP. [ABSTRACT FROM AUTHOR]

A new class nanofluid consisting of Copper Oxide (CuO) nanoparticles, Polyaniline Nanofibers (PANI), and CuO-PANI nanocomposites dispersed in refined, bleached, and deodorized palm olein (RBDL) base fluids have been successfully prepared. The prepared nanofluids were physically characterized to investigate the influence of different nanoparticles and nanocomposites on the dispersion behavior, thermal stability, and thermophysical properties. Physical characterization from TEM, EDX, XRD, TGA, and FT-IR analysis revealed that the CuO nanoparticles had been embedded in the PANI matrix. Sedimentation analysis revealed CuO/RBDL nanofluid achieved stability lesser than one month. Meanwhile, PANI/RBDL and CuO-PANI/RBDL showed there was no sedimentation for almost a month. UV–vis analysis further revealed that all PANI/RBDL and CuO-PANI/RBDL nanofluids samples achieved absorbance drop in the range of 4 to 12% after 30 days of evaluation. FT-IR analysis revealed that nanofluids are chemically stable. The thermal decomposition properties in the TG curve showed that the nanofluids could withstand high temperatures. Viscosity measurement revealed that all RBDL base nanofluids exhibited Newtonian behavior. The thermal conductivity measurement inferred that the most outstanding thermal conductivity was achieved by nanofluid with 10 wt% CuO-PANI nanocomposites with a 31.34% enhancement. While the least was shown by CuO/RBDL with 17.8% enhancement. [ABSTRACT FROM AUTHOR]