Measuring Thermal Conductivity of Fluids Containing Oxide Nanoparticles

Abstract

2. Research Objectives Development and applications of nanoparticle analyzing techniques to examine their thermal behaviors in suspension, including the thermal conductivity, thermal (Brownian) diffusion, thermophoresis and thermocapillaryphoresis. 3. Itemized Progress 3-1. Development of a new miniaturized heated-wire conductivity measurement system Thermal conductivity measurements for CuO and Al 2 O 3 nanofluids have been performed with a newly-developed miniaturized heated-wire conductivity measurement device that require 10-ml capacity versus the first generation Argonne National Laboratory's system requiring 50-ml sample. The current data confirmed, within acceptable discrepancies, previously published data obtained by other research groups (Lee et al. 3 1999, Das et al. 4 2003) under identical conditions. Thus, the measurement accuracy of the newly developed miniaturized device has been validated. More detailed report is presented in Appendix 1. 3-2. Identification of surfactant effect on thermal conductivity When nanoparticles are mixed with base fluid, adding surfactant is essential to enhance the dispersion and minimize the coagulation of nanoparticles. Additionof surfactant, however, can unfavorably change the thermal characteristics of nanofluids. Using the developed miniaturized system, measurements have been made for thermal conductivities of nanofluids with surfactants. The results persistently show substantial decreases of the thermal conductivity in comparison with nanofluids with no surfactant mixed. In order to find the physical explanation for the reduced conductivity, both experimental and analytical studies are carefully explored to be implemented. More detailed report is presented in

Stability and thermal conductivity enhancement of carbon nanotube nanofluid using gum arabic

“…The important key parameter to improve the heat transfer of such fluids is to enhance their thermal conductivity. Over the years [1], solid particles of millimetre or micrometre size have been used to enhance the thermal conductivity of convention fluids. However, it could not be used in practical application due to sedimentation, erosion, fouling and increased pressure drop of the flow channel.…”

“…Knowing the fact that solids have higher thermal conductivity compared to liquids, the suspended particles can change the transport and thermal properties of the base fluids. Various types of nanoparticles (metals and oxides), such as aluminium oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), copper oxide (CuO), copper (Cu), silver (Ag), gold (Au), silica nanoparticles and carbon nanotubes (CNT) have been used [1][2] to enhance the thermal characteristics of the base fluids (water, ethylene glycol, propylene glycol, acetone, transformer oil, etc.). Special requirements for preparation of nanofluids include low sedimentation, even and durable suspension, stable, low agglomeration and no chemical change [2].…”

Influence of Nanofluid on the Performance of Crystallization

“…The magnesium sulfate solution was kept in inner tank of crystallizer and the cold fluid flows through annular space between inner tank and jacket. Agitator is provided in inner tank for continue agitation of solution and the angular speed of agitator is controlled and maintained by control system 13 . The nanofluid is always used as a coolant.…”

Design Parameters to Obtain Al2o3 Nanofluid to Enhance Heat Transfer

“…The great disadvantage of larger nanoparticles is that suspensions tend to become unstable. Experiments have shown that nanofluids were able to enhance the thermal conductivity and convective heat transfer by large margins [4]. Reducing particle size from micro to nanometer, the development of new materials with improved properties could be achieved and many researchers reported results on nanoparticles dispersed in a viscous fluid and on homogeneity [5], [6].…”