Papers by Keyword: Permeability

Abstract: This study aims to assess the impact of time on sawdust usage to enhance the behavior of the clay used in landfills. The soil used in this paper was brought from Büyükçekmece region / Istanbul. Four proportions (1, 2, 3 and 5) of the sawdust were added as a percentage of the dry weight of the soil. Soil-sawdust mixtures were compacted with the optimum water content corresponding to each percentage and samples were extracted. The extracted samples were divided into two groups, the immediate tests were performed on the first group while the second group was kept in special containers for long-term tests after 90 days. A series of undrained unconsolidated triaxial tests (UU) and unconfined compression tests (UCS) were performed on the specimens and compared with the row soil, in the immediate tests, the results from the UU triaxial test showed that the undrained shear strength was increased as the sawdust content increased and then decreased, it was conducted that the optimum sawdust content was 3%, it was increased the undrained shear strength by (39.5%) and (41.44%) for UU triaxial and Unconfined compression tests respectively. After 90 days of the curing period, it found that 2% is the optimum sawdust content, it was increased the undrained shear strength by (202.51%) and (176.64%) for UU triaxial and unconfined compression test respectively. In the immediate and long-term tests, the coefficient of permeability increased by (66.66) and (94.44%) as the sawdust increased from 0 to 5 % respectively. Sawdust increases the hydraulic conductivity of the clay. It can be concluded that the sawdust usage has a remarkable effect on the shear strength of the clay for both immediate and long-term tests.

Abstract: Green sand casting is treated as the most versatile casting process due to their excellent design flexibility that offer complex shapes and ability to reclaim silica sand. The modern foundries are looking for alternate moulding materials to partially replace the high cost silica sand. Cow dung is a naturally available eco-friendly binding as well as additive material and is used to partially replace the silica sand. Improper choice of the combination of moulding sand variables, such as degree of ramming, percentage of cow dung, percentage of clay, and percent of water will affect the moulding sand properties and thereby quality of casting. In the present work, Taguchi method is employed to plan and conduct experiments. Pareto analysis of variance is performed to know the contribution of variables on the moulding sand properties (i.e. compression strength, permeability, loss-on-ignition). Taguchi DEAR method is used to determine the single optimal levels of input factors that enhances the performances of all the sand mould properties. Percent of clay and cow-dung found to be the most dominating factor towards all the sand mould properties.

Abstract: Conform municipal solid waste (MSW) landfills will continue to be used, in the nearest future, in accordance with environmental protection legislation. Due to this fact, the environmental factors such as: water, air, fauna and vegetation, soil, as well as the human health will be affected. The Greenhouse Gases (GHG) emissions (CH₄, CO₂, N₂O, other nitrogen oxides, water vapor steams) are taken into consideration being responsible for a great part of the world environmental changes, 3÷5%, approximately. It is to be noted that, on the national territories, the GHG emissions should be considered due to a bad management of those. The MSW landfilling allows collecting landfill gas (LFG) in a place by collection and treatment of CH₄, CO₂ and H₂S, for economical purposes and human beings health protection. Methane (CH₄) is a strong GHG but has economical value and in the same time, is an important energetic source. Collecting this gas involves important costs. Waste disposal have to be analyzed from the point of view of its enclosed constituents, humidity kept, permeability, biodegradation rate, compacting density, temperature inside the landfill body and atmospheric pressure variations. This article is dedicated to studying the parameters of LFG collection wells, which are used as part of vertical collection systems. For this purpose, the modeling approaches to the main processes occurring in the porous medium of the landfill (MSW) are taken into account.

Abstract: The current chapter focus on the transport phenomenon of polymeric composites . the factors like nature of polymer, temperature, fillers and nature of crosslink can affect the transport properties of a composite. Transport phenomenon in different type of polymer is also studied in the paper.

Abstract: Gas separations through organic membranes have been investigated from last several years and presently it has been accepted for commercial applications. This chapter will focus on membrane based gas separation mechanism as well as its application. This chapter will cover ‘‘diffusivity controlled’’ and ‘‘solubility controlled’’ mechanism and choice of suitable polymers for different gas phase applications like acidic gas, C3+ hydrocarbon, nitrogen, water vapor and helium. Diffusivity controlled mechanism performs on free volume elements of the glassy polymers via hindrance of chain packing by functional groups and restricted by the permselectivity. Other mechanism performs on the basis of molecular structure with affinity towards the target molecule and follows enhanced solution-diffusion rout. Commercially available organic membrane materials for Carbon dioxide (CO₂) removal are discussed along with process design. Membranes based separation process for heavy hydrocarbon recovery, nitrogen separation, helium separation and dehydration are less developed. This article will help us to focus on the future direction of those applications based on membrane technology. Keywords: Membrane, C3+ hydrocarbon, Diffusivity controlled, Solubility controlled, Selectivity, Permeability. ^*Corresponding author: E-mail address: c.bhatta@gmail.com (Chiranjib Bhattacharjee), Tel.: +91-9836402118.

Abstract: Membrane separation technology has been recently attracted more attention as an option for gas separations due to its compact system, ease of operation and low power consumption. In this study, polymer membranes with different percentages of polyurethane were synthesized and submitted to permeability and selectivity tests for the following gases, CO₂, N₂, O₂ and CH₄, at two pressures of 4 and 8 bar and at room temperature. The membranes were characterized by FTIR-ATR, Scanning electron microscope (SEM), Thermogravimetric analysis (TGA) and X-ray diffractometer (XRD). At low pressure of 4 bar and room temperature, the membrane with low percentage of PU, 10 %, presented the higher selectivity to CO₂ in relation to both N₂ and CH₄. The same behavior was observed at a high pressure of 8 bar, with higher selectivity to CO₂ in relation to all studied gases, N₂, O₂ and CH₄, compared to the already analogous reported membranes submitted at greater pressures.

Abstract: The design of artificial metamaterial (MTM) has been proposed as an effective medium with extracted scattering parameter by applying Nicolson-Ross-Weir (NWR) equation to achieved negative permittivity and permeability. The novel architecture of ‘Folded-Line’ Left-handed metamaterial (FL-LHM) consist of split ring resonator SRR is designed and modified using LC lump elements analysis to extend bandwidth and operational frequency at 6 GHz to 12 GHz. In this study, we proposed metamaterial novel unit cell designs and simulate the performance in terms of the distribution of electric and magnetic fields, absorption, transmittance and reflectance. The unit cell of FL-LHM as medium allows controlling electromagnetic waves can cause backwave propagation is observed electromagnetic response that current induced in the closed FL-LHM unit cell. This design has its own advantage in term of FL-LHM parameter width, thickness, and absorption bandwidth and transmittance wavelength, might be severely important for particular purposes such as waveguiding or sensing application.

Abstract: This study explored the application of MOF-modified membrane for gas separation. Microporous aluminum fumarate (A520) was used to modify polyimide (PI) membrane using N-methylpyrrolidone (NMP) as solvent. The MOF-modified mixed matrix membrane (MMM) was subjected to gas permeability tests, using gas permeability apparatus (GPA). GPA results showed that adding 10wt% MOF to the membrane increased permeabilities of N₂ and CO₂ gases by up to 34%, and by 19% for O₂ gas, without compromising selectivity. Further increasing MOF loading beyond 10wt% considerably decreased selectivities despite significantly increased permeabilities. Cahn adsorption experiment confirmed and supported this GPA data. These results indicate that MOF were successfully intercalated with the polymer as revealed by scanning electron microscope (SEM) images. Other characterizations like dynamic mechanical analysis (DMA), x-ray diffraction (XRD), and positron annihilation lifetime spectroscopy (PALS) showed that the interface and mechanical properties of the MMM also improved. MOF loading beyond 10wt% revealed aggregations forming non-selective voids that probably caused lowered selectivity.

Abstract: In this paper comparative study on the compressive strength and permeability of pervious concrete with and without fine aggregate is done. Sand and LLDPE (Linear low density polythene) with varying percentages are used as fine aggregates. Sand is added in percentages of 5%, 10% and 15% of the coarse aggregate in all the mixes. LLDPE powder is added in the percentage of 5%, 10% and 15% of the coarse aggregate in all the mixes. With the addition of fine aggregate the compressive strength of the pervious concrete increases but permeability reduces. The results show that the pervious concrete with LLDPE powder there is a considerable increase in compressive strength as compared to no-fines mix and mix with sand as fine aggregate. The study recommends the use of eco-friendly pervious concrete with LLDPE powder as an alternative to the existing pavements with low volume traffic.

Abstract: This is a theoretical investigation on MHD peristaltic flow of Newtonian and Jeffery fluid through an asymmetric channel with the effect of heat dissipation. The present study, we investigate to include heat dissipation, permeability, Schmidt number and heat generation parameter. The velocity, temperature and concentration profiles are performed in entire study. The governing equations are solved by using the lubrication approach and perturbation technique. The temperature, velocity and concentration fields, trapping phenomena and heat transfer coefficient are plotted by using different parameters. The significance of this study that the pressure gradient with different values of permeability gradually increased, where we observed that from the graph, the pressure gradient is lesser in Newtonian compared to the Jeffery fluid. Moreover, In the trapping phenomena the number of bolus greater in Newtonian fluid compared to the Jeffery fluid by using different values of phase difference and magnetic field parameter.