Effect of Temperature and Nanoparticle Concentration on the Viscosity of Glycerine-water based SiO2 Nanofluids

Dynamic viscosity of SiO2/22nm nanofluids prepared in a glycerine-water (30:70 by volume) mixture base liquid, referred to as GW70, is measured experimentally. Nanofluids with concentrations of 0.2, 0.6, and 1.0 percent are produced, and viscosity measurements are carried out at temperatures ranging from 20 to 80 oC using a LVDV-2T model Brookfield Viscometer. The particle size and elemental composition of nanoparticles are determined using FESEM and EDX. XRD images confirm the SiO2 peaks in the crystalline structure. The rheology of nanofluids is influenced by the nanoparticle’s concentration. In the experimental temperature and concentration range, nanofluids show Newtonian behavior. The viscosity of nanofluids enhanced as particle concentration increased and reduced as temperature increased. For 1.0 percent vol. concentration at 20oC, the maximum viscosity value is achieved, and for 0.2 percent vol. concentration at 80oC, the lowest viscosity value is observed. The viscosity of the glycerine-water base fluid was also determined at 20, 40, 60, and 80 degrees Celsius. The viscosity ratio of nanofluids to the base liquid is found to be more than one for all the nanofluids. This viscosity data is useful to estimate HTC of glycerine-water-based silica nanofluids.

Effect of Surface Microtexturing on Friction at Unidirectional Sliding Depending on Lubricant Viscosity

Effect of surface microtexturing with spherical dimples of 60 μm diameter on friction behaviour of steel 100Cr6/sapphire pairs was studied as function of lubricant viscosity. Tests were run at unidirectional sliding up to 0.30 m/s using a pellet-on-disc geometry with flat contact area and drip lubrication with liquids such as glycerine-water solutions, distilled water and different mineral oils without additives. The texture pattern was produced on the polished sapphire discs by laser ablation processes. Friction force and film thickness of the lubricating liquid were continuously measured during the tests at different sliding velocities. Results showed that effectiveness of microtexturing in reducing friction and increasing load-carrying capacity depended on viscosity of the lubricant, operating conditions such as sliding velocity and applied load as well as texture parameters.

Analysis of production tests in processing the mixture of solid and liquid biologically degradable wastes by anaerobic fermentation

This study concerns the analysis of operating anaerobic fermentation systems of agricultural biogas station and implementing a suitable system enabling the use of a mixture of solid and liquid biowaste. The tests made use of liquid substrates commercially offered to biogas station operators. The study evaluates practical measurements at an agricultural biogas station in order to evaluate the biogas production from these substrates and the efficiency of transforming input material to usable energy. The use of such treated substrates for the anaerobic fermentation technology may have a substantial influence on the volume of dosed energy crops. The mixture of input substrates consisting of liquid cattle excrements, silage corn, solid and liquid waste from food processing, animal waste and glycerine water was experimentally validated. This mixture was compared with the operation using liquid cattle excrements and silage corn. It was concluded that the proposed composition of input raw materials makes it possible to increase the production of biogas and el. power. On the other hand, it was identified that the energy content of the input raw materials is not optimally transformed into usable energy. This is why the proposed mixture of input materials with biowaste is not recommended for use at the used proportion.

Operating tests analysis of liquid biologically degradable waste processing by anaerobic fermentation

This study concerns the analysis of operating anaerobic fermentation systems of agricultural biogas station and implementing a suitable system enabling the use of liquid biowaste. Based on the comparison of the technological solutions and operating parameters of specific equipment a system enabling the utilisation of biowaste has been designed. The tests made use of liquid substrates commercially offered to biogas station operators. The study evaluates practical measurements at an agricultural biogas station in order to evaluate the biogas production from these substrates and the efficiency of transforming input material to usable energy. The use of such treated substrates for the anaerobic fermentation technology may have a substantial influence on the volume of dosed energy crops. The mixture of input substrates consisting of liquid cattle excrements, silage corn, liquid food-processing waste, animal waste and glycerine water was experimentally validated. This mixture was compared with the operation using liquid cattle excrements and silage corn. It was concluded that the proposed composition of input raw materials makes it possible to increase the production of biogas and el. power. On the other hand, it was identified that the energy content of the input raw materials is not optimally transformed into usable energy. Therefore, the proposed mixture of input materials with biowaste is not recommended for use.

The lift force on a bubble in a sheared suspension in a slightly inclined channel

The lattice Boltzmann method was applied to simulate the free rise of monodisperse non-coalescing spherical bubbles in slightly inclined channels bound by solid walls. The Reynolds number based on the relative velocity between the bubbles and the fluid ranged from 4 to 16, the volume fraction from 5% to 10% and the inclination angle from 2° to 6°. The simulations revealed that the weak buoyancy component normal to the walls led to a layer of bubbles near the upper wall and a depleted layer near the bottom wall. These thin layers drove a nearly viscometric shear flow within the bulk of the channel that allowed an unambiguous determination of the lift force in a sheared homogeneous and freely evolving bubble suspension. The lift force coefficients calculated from our simulations were always higher than those for isolated spherical bubbles, suggesting that the lift force is enhanced by hydrodynamic interactions among the bubbles. Experimental measurements of the velocity gradient in 10% volume fraction bubble suspensions in glycerine–water–electrolyte mixtures in slightly inclined channels yielded lift coefficients in excess of those predicted for isolated bubbles and confirmed the qualitative predictions of the simulations.

Withdrawal of a Conical Pin From a Pool of Liquid

The development of biochips leads to a straightforward, fast and cost effective method to obtain valuable genetic information. A key element of the emerging biochip technology is a microarray system, which fabricates high-density samples on solid materials of a microscopic area. In particular, dots of test liquid are printed on solids by a system of pins constituting a microarray. At present, however, the technique cannot make dots of arbitrary equivalent and controllable size. On the other hand, printing pins in microarrays represent themselves as a particular example of dip coating. In the experiments of the present work, a model of tapered stainless steel needle was withdrawn from different glycerine-water mixtures. Thicknesses and volumes of the withdrawn liquid films were measured as a function of the needle geometry, immersion depth, withdrawal rate, and physical parameters of the liquid. The experimental data are analyzed as a function of the capillary number Ca based on the withdrawal speed and compared to the predictions of the modified Landau-Levich-Deryagin (LLD) theory. The results show that for Ca < 10-2 the thickness and the volume of the liquid follow the Ca2/3-scaling, while for Ca >10-2 — the Ca½-scaling, as it is expected from the LLD theory. Flow visualization is utilized to resolve the detail flow structure. The results put the key element of the pin-printing technology exploited in microarrays into a familiar hydrodynamic context of dip coating. This allows one to expect that under appropriate operational conditions, high-precision sampling could be attainable.

Flowmetering of Shear-Thinning Non-Newtonian Liquids (Keynote)

This paper describes the results of an investigation into the performance of Coriolis, Electromagnetic, and clamp-on single-beam Ultrasonic flowmeters operating with non-Newtonian liquids. The flowmeters have been tested on Newtonian liquids (water and a glycerine/water solution) and non-Newtonian liquids (various polymer solutions and a synthetic clay) with flow rates that span the laminar and turbulent regions. It has been shown that the Coriolis flowmeter operates within the manufacturer’s specification with non-Newtonian liquids. The Electromagnetic flowmeter showed a slight deviation during transition, typically 1%. The Ultrasonic flowmeter showed very significant deviations during transition, typically 15%. It has been clearly demonstrated that flowmeters which are sensitive to flow velocity profile are particularly unsuitable for use with non-Newtonian liquids. Not only do non-Newtonian liquids have different flow velocity profiles to Newtonian liquids, they also have different criteria for laminar/turbulent transition.