Papers by Keyword: Particle Size Distribution (PSD)

Abstract: Recently the study on the convective heat transfer properties of the nanofluids has gained remarkable importance. Nanofluids are stable dispersions of nanoparticles into a base fluid. These are experimentally found to possess enhanced mechanical and heat transfer properties compared to the parent base fluid. Previous studies confirm that of all the nanofluids, the ones prepared using MWCNTs with distilled water as the base fluid produced a maximum enhancement in the thermal conductivity of the dispersant. This widens the potential scope of MWCNTs nanofluids as coolants in different applications. Despite its exceptional properties, preparation of a stable water based MWCNTs nanofluid often involves a tedious process because of their hindrance to disperse in organic solvents. Functionalization is the process of surface modification of CNTs to reduce their hydrophobicity thereby improving their dispersion effect in organic solvents. Functionalization by chemical treatment is the most effective method in maintaining the long term stability of the nanofluids, but these processes often involve treatment with strong chemicals which affects the size distribution and morphology of the carbon nanotubes. The current study investigates the stability and particle size distribution of MWCNTs nanofluids functionalized by different processes and reports the most effective process for functionalization of MWCNTs.

Abstract: For a developing country such as Malaysia, riverbank/bed filtration (RBF) technology is still new and only few efforts have been made to understand the RBF mechanism and processes. Soil characteristics play important roles in determining the water quality and the ability of water to be abstracted from the wells during RBF process. A research has been carried out to identify the characteristic of riverbank soil at different layers in the pumping well (PW) borehole at Kota Lama Kiri, Kuala Kangsar, Perak, Malaysia. Soil samples were collected during the development of PW for RBF application. The maximum depth of PW was 8.50 metre. The soil samples were transported to Geotechnical Engineering Laboratory, School of Civil Engineering, Universiti Sains Malaysia and the properties were determined by a series of laboratory test. Soil particle size distribution (PSD) and hydraulic conductivity were obtained from sieve analyses and constant head test with reference to BS 1377: Part 1-9;2:1990. Laboratory results show that the value of C_u (coefficient of uniformity) for the soil samples within the borehole of PW was found to be within the range of 2.00 to 10.00 while the value of C_c (coefficient of gradation) lies in the ranges of 0.06-1.19. The One Way Analyses of Variance test was performed using Minitab statistical packages and the results indicate that the p-value was 0.996, where there was no significance difference between the mean sizes of soil samples within the PW. The hydraulic conductivity, k for PW ranges between 0.10-0.91 cm/s. Soil samples from depth 6.00-7.00 metres has the highest hydraulic conductivity, which is 0.91 cm/s. The overall well production from the pumping test was found 112.10 m³/hr.

Abstract: In light extinction particle sizing, a classification inversion algorithm is proposed for the non-spherical particles. The measured spheroidal particle system is inversed with different particle distribution functions and classified according to the inversion errors in the dependent model. Simulation experiments illustrate that it is feasible to use the inversion errors to inverse the spheroidal particle size distribution in the light extinction particle sizing technique and the inversion results are steady and reliable, which avoid the defects that the type of the size distribution must be assumed beforehand for the light extinction method.

Abstract: The hydrolysis product was prepared by added-seed thermal hydrolysis method with industrial titanyl sulfate solution. The influences of some factors (such as preheating temperature, sodium hydroxide concentration and activity of seeds) on the particle size and particle size distribution (PSD) of hydrolysis product were studied. The product was characterized by particle size analyzer and filtering property test. The results showed that all these factors had great impacts on PSD of product and its filtering property, the narrowest coefficient of variation (C.V.) was 43.0% and the fewest filtering time was 311s. The optimal conditions were as follows: preheating temperature was 90°C; NaOH concentration was 8.0-8.5%; activity of crystal seeds was 100-140 mL.

Abstract: This paper presents the results of a laboratory study on the effect of oil contamination on the particle size distribution and plasticity characteristics of lateritic soil. The soil was artificially contaminated with a maximum 6 % oil content by weight of dry soil. The results show that there was a substantial reduction in the amount of fines content with higher amounts of oil in the soil matrix. The percentage of fine fraction in the natural soil was 86.9 % and on contamination with maximum 6 % oil content by weight of dry soil at optimum moisture content (OMC) the fine fraction reduced to 1.4 %. The plasticity index decreased from 16.0 to 8.5 % when contaminated with 6 % oil content by weight of dry soil. The plasticity modulus (PM), plasticity product (PP), the shrinkage modulus (SM) and the grading modulus (GM) decreased with increasing amounts of oil content.

Abstract: Ferric chloride (FeCl₃) and polyacrylamide (PAM) are used as flocculant and coagulant aid for treating the dredging wastewater from Chongqing Liangtan river. The effects of dosages of flocculant and coagulant aid on removal rate of turbidity, suspended solid (SS) and COD were investigated. The effects of Zeta potential and particle size distribution on treating performance were also discussed. It was found that the optimal flocculation performance was achieved when the absolute Zeta potential approached zero. Lower dosages of flocculant and coagulant aid were needed when the average particle size of SS in dredging water was smaller.

Abstract: In respect to conventional particle size distribution, the fractal size dimension (FSD) has become a powerful tool for characterization of particles.In this paper, we applied both the single fractal law and the bi-fractal approaches to analyze the fractal and mutifractal characteristics of the Qingshuiying coal particles in the ultra-fine pulverizing process. The relationship between FSD and the ultra-fine pulverizing time was detected and had certain guidance meaning for optimizing the operational parameters and reducing energy consumption of the ultra-fine pulverization.

Abstract: Particulate flow is commonly encountered in industries as well as in many other chemical and mechanical engineering applications. The accurate measurement of particle size distribution is of the utmost importance since it decides the physical and chemical characteristic of the particles. The light extinction method can be used for in-line monitoring of particle systems thus providing real time measurements of both particle size distribution and particle concentration. In light extinction particle sizing, a classification inversion algorithm is proposed for the circular cylinder particles. The measured circular cylinder particle system is inversed with different particle distribution functions and classified according to the inversion errors in the dependent model. The simulation experiments illustrate that it is feasible to use the inversion errors of object functions to inverse the circular cylinder particle size distribution in the light extinction particle sizing technique. This classing inversion algorithm can avoid the defects that the type of the size distribution must be assumed beforehand for the light extinction method.

Abstract: Liquefaction of sand soil such as silty sand was quite popular in earthquake. Gravel liquefaction, by contrast, was seldom. Soil liquefaction was popular in Chengdu Plain in Wenchuan Earthquake and there was ejeched gravel in several sites. Through drilling and tests for typical liquefied sites, the study on distribution of layers, compactedness , shear wave velocity, particle size distribution had been performed. The results shows: (a) Soil distribution is similar in 2 typical liquefied sites which are located in different location and different seismic intensity regions. Gravelly sand was the only cohesiveless soil which is possible to be liquefied,so gravel liquefaction was true; (b)The liquefied gravel was the characteristics of shallow, loose , low shear wave velosity and. the Holocene sediment. (c) Particle graduation of liquefied gravelly sand was poor and there was a short of soil fraction.

Abstract: More cuttings producing in higher penetration rate of gas drilling are usually in the larger non-uniform size at the bottom and in the smaller uniform size back to the wellhead. It is indicating that cuttings in the well should be appeared in the successive breaking in the process of upward migration. According to the particle broken theories, the successive breaking phenomenon were analyzed, and given the calculating method for the probability of secondary impact crushing, and applied the breaking process matrix and the particle size distribution function to the cuttings migration crushing in the whole wellbore. The calculating results show that the cuttings in the wellbore are broken by the uneven size volumetric fracture progressively turned into the surface fracture of the uniform process, and ultimately stabilized the small size distribution.