Papers by Keyword: Particle Size Distribution (PSD)

Abstract: Phase change materials (PCMs) can be incorporated with building materials to obtain novel form-stable composite PCM which has effective energy storage performance in latent heat thermal energy storage (LHTES) systems. In this study, the PCM gypsum boards were prepared by mixing the gypsum with the power storage composite prepared by mixing with the paraffin as latent heat storage material, porous ceramsite skeleton with different particle size distribution (PSD) as adsorption matrix, and sodium alginate as reaction material. The PSD of power storage porous ceramsite were obtained by using digital camera and image process software, and the conductivity factor of PCM gypsum boards were measured by heat test machine. The directed grey relational grades between the PSD and the conductivity factor were calculated by means of grey relational rule in order to investigate the influence of PSD on the conductivity property of PCM gypsum boards. The results indicated that the porous ceramsite with size ranging from 0 to 3.0 mm could enhance the conductivity property of PCM gypsum board slightly, the porous ceramsite with size in a range from 3.0 to 14.0 mm, especially those with size range from 3.0 to 4.0 mm could obviously weaken the conductivety property of PCM gypsum board.

Abstract: The cost for nonpoint source in urban area tends to increase as it's distanced farther from the pollution source. Thus it's more effective to dispose of the pollution at the pollution source. It becomes more difficult when nonpoint source is flowed into the surface water by stormwater. In case of combined sewer, increasing stormwater on impermeable surface causes the Combined Sewer Overflows (CSOs) containing the high level of pollutants which runs into the water system through the storm overflow diverging tank without treatment process. A huge amount of CSOs is generated instantly and as it carries the pollutants on impermeable surface as well as the deposits in sewage pipe, it's necessary to develop the technology for treatment of CSOs. This study was intended to develop the solid fabric filter which will be suitable for treatment of CSOs and the characteristic and performance of solid fabric filter were evaluated.

Abstract: Two different size-grained soils were subjected to column experiments with a hydraulic loading representing two years’ rainfall. Leachates were collected and analysed for pH and temperature and for eight trace metals, namely; Iron (Fe), Copper (Cu), Chromium (Cr), Nickel (Ni), Lead (Pb), Manganese (Mn), Zinc (Zn), and Silica (Si). The analysis was conducted using an inductively coupled plasma (ICP) method of spectrometry. The results show different extractable metal concentrations from the two soil samples.

Abstract: The success of a refractory castable is largely due to the quality of its properties and ease of application. Self-flow refractory castables (SFRC), with high flowability index (>130%), can be easily accommodated in a mould without the application of external energy, being ideal for the manufacture of monolithic linings. SFRC castables without cement require a matrix of very fine particles, which guarantees improved rheological behaviour and performs the role of the binder in the absence of the refractory cement. The presence of the aggregate (coarse particles) hinders the flowability index, but improves the castable mechanical strength and reduces firing shrinkage, and also contributes to the reduction of the castable costs. The control of the maximum paste thickness (MPT) allows the reduction of the coarse particles interference, minimizing the number of contact points among the grains and avoiding the formation of an aggregate skeleton that impairs the flowability of the mixture. In the present work, 100% alumina SFRCs without cement were produced with a fixed matrix of fine particles, whose particle size distribution was optimized using statistical techniques (mixtures design and triangular response surfaces). Different aggregate particle size distributions were used, with several MPT values, with the objective of evaluating which was the mean distance that maximized the flowability index, simultaneously ensuring good mechanical strength for the refractory castable. Ensuring a minimum surface area of 2.22m2/g, the mixtures reach the self-flow turning point with a minimum water content and the maximum flowability is obtained for an aggregate particle size distribution modulus of q=0.22, and consequently an optimized MPT value. SFRC with high mechanical strength (>60MPa) were obtained.

Abstract: The aim of the work was to examine the influence of pH, high power ultrasound, surfactant and dopant quantity on the particle size distribution of ZrO2:Pr3+, with praseodymium content varying between 0.05 and 10 %. The nanopowders were obtained via a hydrothermal microwave driven process. To establish if the dopant was located on the surface of the zirconia nanoparticles, the particle size distribution, as a function of pH, was measured to obtain an estimate of the isoelectric point of the samples. All results indicated that the dopant was concentrated on the surface: the measurements of the particle size distribution show that the pH corresponding to maximum average particle size changes towards higher values when the Pr content increases. Measurements of the particle size distribution dependency on the application of high power ultrasound and the addition of the sodium dodecyl sulphate surfactant show that, under certain conditions, there is a better stabilisation of the nanopowders in a dispersion and undesirable agglomeration is hindered.

Abstract: In this research, a up-flow filtration device was developed for the on-site treatment of urban stormwater runoff during storm events, and particle removal characteristic of porous polypropylene as a filter material was experimentally examined. The up-flow filtration device showed high removal efficiency, more than 90% (mainly 95-98%) of the SS concentration of influent particles. After the sedimentation in the bottom part of up-flow filtration device, the up-flow filtration filled with porous polypropylene material was able to remove more over 70% of the SS concentration in the up-flow. The increase rate of captured particle amount retained in 10, 20 cm from the bottom of filter bed was lower while flow rate increased. This is attributed to the fact that fine particles detached or not removed by the bottom of filter bed were mainly retained in that section. The particles (mainly finer particles) captures were increased by those particles (mainly large particles) retained in the initial stage for influent particles. However, the improvement of particle removal efficiency (as SS concentration) was not observed along with this phenomenon. The reason may relate to the fact that the particles retained by the captured particles in the initial stage were fine particles.

Abstract: For precise property control of sintered products, it is important to know the powder characteristics, especially the packing density of the powder. In a previous work, we developed a packing simulation program that could make a packed bed of spherical particles having particle size distribution. In order to predict the packing density of the actual powder that consisted of nonspherical particles, we combined the packing simulation with a particle shape analysis. We investigated the influence of the particle size distribution of the powder on the packing density by executing the packing simulation based on particle size distributions of the actual milled chromium powders. In addition, the influence of the particle shape of the actual powder on the packing density was quantitatively analyzed. A prediction of the packing density of the milled powder was attempted with an analytical expression between the particle shape of the powder and the packing simulation. The predicted packing densities were in good agreement with the actual data.

Abstract: The filling property of the binder treated iron based powder made of atomized iron powder was compared with that of the one made of reduced iron powder. The latter one showed a better filling property than the former one, although the original reduced powder showed a worse flow rate. Changing the particle size distribution of the original atomized powder from wide to narrow like the original reduced iron powder, improved the filling property of the binder treated powder. As a result, the particle size distribution of the original iron powder was found to strongly affect the filling property of the binder treated powder.

Abstract: Plane honing machining of aluminum nitride (AlN) was investigated in this study. AlN has advantageous thermal and dielectric characteristics and is in great demand as a semiconductor mounting board or packaging parts material. However, as AlN is a sintered material, the AlN grains readily detach during machining making it difficult to obtain fine surface roughness at high efficiency. In previous studies, we have developed a new plane honing method that makes it possible to grind hard and brittle materials. In this paper, plane honing experiments of AlN were carried out using a resinoid or vitrified bond wheel. Fine surface roughness could be obtained using the resinoid bond wheel but there was low-machining efficiency due to burying and detachment of abrasives. The vitrified bond wheel, however, enabled high efficiency grinding but resulted in traces of detached AlN grains forming at the machined surface. Highly efficient mirror grinding of AlN could be achieved by using a vitrified bond wheel for semi-finishing and a resinoid bond wheel for finishing.