Advanced Materials Research Vols. 550-553

Abstract: Abstract: The 3D flow field generated by a dual-impeller in the agitation of glycerin fluid was simulated using the commercial CFD package. The flow was modeled as laminar and a multiple reference frame (MRF) approach was used to solve the discretized equations of motion. The velocity profiles with a dual-impeller rotating at constant speed of 200r/min and at different layer clearances were obtained. By analysis to their axial and radial velocity vector plots and velocity distribution curves, it is found that the velocity distributions of the dual 6-bladed radial disc turbines (2-6DT) are better when the clearance is bigger or equal to the T/2, accompanied with the flow field pattern of parallel flow. Moreover，when the clearance is smaller or equal to the T/3, there are more advantages for 6-bladed radial disc turbines + pitch 4-bladed turbines (6DT+PTB) than other combinations，followed by the flow field pattern of connected flow.

Abstract: The experiments of mixtures of SiO2 and ZnO nanoparticles in a vibrated fluidized bed were carried out. The effects of ratio of initial static bed height to diameter (h0/D), vibration amplitude (A), frequency (f) and mass ratio of mixed SiO2 and ZnO nanoparticles on the behavior of mixtures of SiO2 and ZnO nanoparticles were studied. The experimental results proved that the fluidization quality of mixed nanoparticles can be enhanced under h0/D=1, A=3.0 mm, f =45Hz, leading to larger bed pressure drops at low superficial gas velocities. The bed height decreases with increase in the mass ratio of ZnO component of the mixture.

Abstract: Based on the pore size distribution simulation and the derivation of the effective diffusion coefficient, a mathematical model describing the mass transfer and chemical reaction in a cylindrical gas sensitive porous medium is formulated. The reaction features and the effective utilization of the gas sensitive porous medium are analyzed under different pore size distribution. The results indicate that, an increase in porosity or in the most probably pore diameter leads to a higher mass transfer rate of the target gas, while the surface chemical reaction ability decreases. Depending on the calculated value of the Thiele number, the variation of the gas sensitivity and the effective surface utilization can be analyzed. The gas sensitivity and the effective utilization coefficient of the gas sensitive porous medium can be controlled by adjusting pore structure parameters. This will be useful for the pore structure design of gas sensor and choosing the most reasonable operation conditions.

Abstract: A T-junction with a horizontal main pipe and a vertically downward branch was employed to investigate phase separation phenomenon of oil-water two-phase flows at two segregated flow patterns. Water and kerosene (density of 796 kg/m³) were chosen as the working fluids. The effects of inlet flow pattern, mixture velocity, and water cut on the phase separation were examined. The results show that the variation of the mixture velocity in the same inlet flow pattern has little influence on the phase split and the phase separation highly depends upon the inlet flow pattern. The lower the mixedness of the inlet flow, the higher the separation efficiency can be achieved. The higher the water cut, the lower the separation efficiency peak can reach.

Abstract: As a result of the base-rock corrosion effects and the suspension-carrying capability of polymer in the system of strong base ASP flooding, the concentration of silicon ions in reservoir liquid increases. As the liquid flows into the surface pipelines with tracer heating water injecting, thermodynamics and kinetics conditions change. Suspending power and pH value also decrease. Heavy oil (which content is more than 25%), silts, carbonates and silicates co-deposite, which can cause surface pipelines jamming and even production stopping. Physical or chemistry methods can prolong the rinsing cycles of surface pipelines. Pilot tests indicated that injecting resistance sedimentation agents cost little which had a long rinsing cycle above one year. Hot washing technology had a low cost but with a short rinsing cycle about 2-4 months and the treatment efficiency was easy influenced by the content of oil in blockages. Cavitating water jets technology had good effects and its rinsing cycle were 6 months but cost was high.

Abstract: In the spectral emissivity measurement of material, one domain uncertainty source is the measurement of the actual sample surface temperature. This paper presents a novel method on heating the sample—the four channel hot air heating method, with the purpose of making sure that the heat flux is nearly equal to zero inside the sample, which is essential for the low thermal conductive materials. So the temperature difference between the sample surface and inside can be neglected. The FEA (Finite Element Analysis) method, through using FLUENT, was adopted to numerically simulate the temperature profile of the new heating system. The simulation results showed that temperature profile at the direction of X in ±15 mm ranges at the central area of exits of the air-guide duct is almost at ±5°C and at the direction of Y in ±15 mm ranges is nearly ±10°C. The temperature profile was experimentally studied by using thermocouples, the numerical simulation and experimental results were in good coherence.

Abstract: This paper proposes a new isolation module, which is composed of double-layer tubular structures and the middle filling material. The hoop vibration isolation module is set somewhere out of pier footings of the footbridge, which presents some advantages such as good reliability, convenient construction, limited occupation areas, little damage to the environment and low cost. The energy of the vibration wave is confined at the most degree outside of the bridge pier, which reduces the vibration of beams and piers of footbridge. The present work gives an account of the experimental investigation on mitigation effects of the new vibration isolation module. The horizontal and vertical accelerations at test points under various working conditions were presented in this paper. Vibration levels were calculated to analyze the regularity of vibration attenuation, compared with no measures of vibration isolation. The results can provide some basic data for the mitigation of environment vibration arising from traffic loads.

Abstract: An experimental study, in a trapezoidal closed cavity had been led in our laboratory. The considered cavity includes a vaporizing horizontal surface, two condensing ones; one is of glass and the other of aluminium surface. It is cooled down by flowing water. The other walls are thermally isolated. Acquired results allowed to identify the regime of air flow inside the cavity, to assess the mean exchange coefficients of heat and mass, across the three walls and to write a correlation for the mean Sherwood and Nusselt numbers, established for laminar flow regime. These results are important to model many solar uses as solar distillers, solar dryers, etc… We present, in this report experimental results and in a future paper, the written mathematical model and a numerical simulation.

Abstract: The composite polydimethylsiloxane PERVAPTM 4060 was used for separation of methanol/water solutions by using pervaporation technique. The effect of feed concentration, feed temperature, and feed flow rate were investigated for the separation performance. The experimental data showed that increasing of the feed methanol concentration from 0.5 to 10 wt% resulted in an increase in total permeation flux up for to 35 % whilst the separation factor (α) decreased by 85%. The results also showed that increasing operating temperature from 40 to 60 °C caused an increases in methanol permeance up to 130%.

Abstract: In this work, an aqueous solution containing succinic acid, formic acid, acetic acid, and lactic acid with the concentrations of 420, 50, 40, and 10 g.L-1 was employed as the model solution. The solution was pumped into a reactor followed by an addition of the equal volume of anhydrous ethanol. The solution was heated and the esterification reaction was commenced by an introduction of 2% sulfuric acid (w/v). A highly efficient fractionating column designed in our laboratory was employed to shift the conversion beyond the thermodynamic equilibrium conversion by continuous removal of water from the reactor as distillate. In addition, a vapor permeation technique using a commercial hydrophilic polymeric membrane was successfully employed to dehydrate the distillate before returning the dehydrated ethanol into the reactor. This integrated esterification-distillation process allowed a complete conversion of organic acids to the corresponding esters. Due to their much different boiling points, diethyl succinate was completely separated from the other esters by using a vacuum fractionation technique.