The viscometer uses the turning-fork vibration method at a constant resonating frequency of 30 Hz to determine the vicidity of fluid samples based on power differentials that maintains the resonating frequency. The measuring cup of the apparatus is equiped with a water jacket connected to a programmable thermal bath for efficient temperature control of samples, Figure 3. Japan with viscosity measurement limits of 0.3 – 10,000 mPa.s. The viscosity equipment used is a sine wave vibro-viscometer SV-10 from A&D Company Ltd. During this process of homogenization the sample was kept in a programmable temperature bath o (LAUDA ECO RE1225 Silver temperature bath) and the temperature maintained at 15± 0.1 C. The amplitude and pulse-pulse mode factors were kept constant at 75% and 80% of the maximum respectively. The mixture was sonicated continuously for 3 h and 6 h with a 24kHz UP200S Hielscher ultrasonic processor for laboratory with S14 sonotrodes to obtain an homogenized dispersion of nanoparticles in the glycerol. A precalculated weight of nanoparticles coresponding to a known volumetric fraction of the desired nanofluids samples were measured using a digital weighing balance (Highland HCB1002, max: 1000g, precision: 0.01g, from Adam equipment ) and the base fluid is added to the corresponding desired weight. The -Al 2 O 3 – glycerol was prepared using the popularly known two – step method of preparation by direct dispersion of the nanoparticles in the base fluid. Glycerol was procured from Merck Chemicals South Africa, with 99.5% purity and viscosity of 1412 mPa s at 20 o C. The pattern corresponds to Corundum structure (Al 2 O 3 ) from the JCPDS database and the broadening of the peaks indicates the small size of the particles ( 80 is typical of aluminium. The XRD patterns of -Al 2 O 3 (Figure 2) specimen was recorded in the 10° - 90° 2θ range with a step size of 0.001° and a counting time of 12.705 seconds per step. An XPERT-PRO diffractometer (PANalytical BV, Netherlands) with theta/theta geometry, operating a cobalt tube at 35 kV and 50 mA was used to obtain the XRD pattern. As shown in Figure 1, though there were agglomeation of nanoparticles, but we were able to identified that the nanoparticles are nearly spherical as is, while its norminal size is about 17 nm with few aberations of 50 ± 3 nm. To further accentuate this, Transmission electron microscopy (TEM) images were obtained on a JEOL JEM-2100F microscope operated at 200 KV, to determine the size and morphology of the nanoparticles as supplied. It is of 99.97% purity with true density of 3.7g/cm, nearly spherical morphology and diameter between 20 – 30 nm as stated by the manufacturer. The -Al 2 O 3 nanoparticles used in this investigations were manufactured by Nano Amorphours Inc. This work is carried out in the Einstein’s concen tration regime of ≤ 2%, temperature range of 20 – 70 o C and sonication period of 3 h and 6 h respectively. Hence, this gave credence to the present research which focuses on the viscosity and electrical conductivity of glycerol based alumnia nanofluids. Nevertheless, there are no experimental data on thermal conductivity, electrical conductivity and viscosity of glycerol based nanofluids of alumina. Much of the work done in this emerging field as portrayed above and widespread in the literature is on Al 2 O 3 with different base fluids. Rheological characteristics of the samples in a rotating viscometer indicated that the nanofluids are Newtonian in nature however, for the volume fraction of 2.54%, 5.54% and 11.22% tested the viscosity enhancements were ambiguous and unprecedentedly high. However, at a relatively higher temperature of 352.5K the enhancement was 18% while the maximum enhancement was observed at the maximum nanoparticle volume fraction of 11.22% to be 38.1%.
At the lowest nanopartcles volume fraction of 1% the enhancement of thermal conductivity was not more than 5% at all temperatures below 323.15K.
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