Numerical Simulation of Solar Air Heater using Paraffin Wax-Aluminum Compound as Phase Changing Material

This paper presents a theoretical investigation of solar air heater using phase change material (PCM). PCM used in present configuration is homogenous mixture of paraffin wax with Aluminium powder. The purpose of using Aluminium powder with paraffin wax is to increase the thermal conductivity. PCM mixtures are encapsulated in cylinders and are used as solar absorbers. Using MATLAB program, the effect of different parameters is studied. It has been observed that with increase in mass flow rate, air outlet temperature decreases and freezing time of cylinder decreases. However, at constant mass flow rate, with increase in cylinder radius, air temperature decreases and while freezing time increase sharply. The different parameters have to be chosen such that performance of solar air heater can be optimized.

Анализ водородоустойчивости алюминиевых сплавов

It was established by the methods of quantum chemistry that tungsten W and rhenium Re are the most effective additives that increase the hydrogen resistance of aluminum Al. It is shown that W and Re strongly compress aluminum, but at the same time have a rather large covalent radius. In addition, each W and Re atom form stable chemical bonds with 12 Al atoms. As a result, the W and Re atoms strongly bind Al atoms significantly increasing the energy of vacancy formation and slowing down the process of hydrogen embrittlement. All basic physical and mechanical properties of the most hydrogen-resistant aluminum compound WReAl24 have been calculated using density functional theory.

Preparation and Application of Modified Montmorillonite Dispersion for Chrome-less Tanning of Leather

The properties of modified montmorillonite dispersions for their use in the chrome-less leather tanning method were investigated. It is proposed to modify montmorillonite with aluminum compounds and to combine the obtained dispersions with chromium compounds for leather treatment. Modification of montmorillonite dispersions by aluminum compound within 5.0-7.0% Al2O3 of the weight of the mineral contributes to obtaining the most stable positively charged montmorillonite dispersions. The use of the obtained montmorillonite dispersions is effective for stabilizing the collagen structure and increasing the temperature resistance of collagen. The use of modified montmorillonite dispersions combined with a chromium tanning agent contributes to the introduction of chrome-less tanning. 0.75% of Сr2O3 and 3.0% of modified dispersion of montmorillonite of the weight of the pelts in conversion for mineral weight are considered the optimal consumption of chromium tanning agent.

Utilization of ZeoliticWaste in Alkali-Activated Biomass Bottom Ash Blends

This study aims to investigate the effects of ammonium-bearing zeolitic waste (FCC) on alkali-activated biomass bottom ash (BBA). FCC was obtained from the oil-cracking process in petroleum plants. In this study, two types of production waste were used: biomass bottom ash and ammonium-bearing zeolitic waste. These binary alkali-activated FCC/BBA blends were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) methods. The compressive strength of the hardened samples was evaluated. The results show that the samples made from alkali-activated BBA biomass bottom ash had low (8.5 MPa) compressive strength, which could be explained with low reactive BBA and insufficient quantities of silicon and aluminum compounds. The reactivity of BBA was improved with incorporating zeolitic waste as an aluminosilicate material. This zeolitic waste was first used for ammonium sorption; then, it was incorporated in alkali-activated samples. Additional amounts of hydrated products formed, such as calcium silicate hydrate, calcium aluminum silicate hydrate and calcium sodium aluminum silicate hydrate. The silicon and aluminum compound, which varied in zeolitic waste, changed the mineral composition and microstructure of alkali-activated binder systems. NH4Cl, which was incorporated in the zeolitic waste, did not negatively affect the compressive strength of the alkali-activated BBA samples. This investigation proved that waste materials can be reused by producing alkali-activated binders.

Stable blue-emissive aluminum acetylacetonate nanocrystals with high quantum yield of over 80% and embedded in polymer matrix for remote UV-pumped white light–emitting diodes

Blue-emissive nanocrystals (NCs) with high photoluminescence quantum yields (PL QYs) and excellent stability are essential for lighting and displays. Here, a facile top-down approach (including two steps: thermal annealing and ultrasonic treatment) by using aluminum acetylacetonate (Al(acac)3) as a precursor is adopted to fabricate blue-emissive Al(acac)3 NCs with high PL QY reaching 81.8%, the highest reported value for the aluminum compound-based NCs so far. Additionally, the as-fabricated Al(acac)3 NC solution (in toluene) exhibits high stability under air atmosphere condition, maintaining 61.2% of initial PL QY after 1 year. Furthermore, solution-processed Al(acac)3 NCs/poly(methyl methacrylate) (PMMA) composite film with blue emission is demonstrated. Finally, combinations of the blue-emitting Al(acac)3 NCs/PMMA composite film with red-emitting and green-emitting CuInS2 composite films are realized, resulting in remote ultraviolet-pumped white light-emitting diodes with a high color rendering index of 91. These findings inform new blue-emissive NCs and composite films, potentially paving the way to design new structures of lighting and display devices.

Resarch on Mechanical Properties of Al 6061 Alloy Processed By FSW

The reason for this investigations is to improve the mechanical living arrangements of aluminum composite 6061 by means of grinding mix preparing (FSP), strong state strategies to change the microstructure utilizing the warmth of contact and blending. Aluminum compound 6061 is broadly utilized inside the assembling of lightweight structures with a proportion of power to-weight high and proper erosion opposition. Welding is the essential creation technique 6061 amalgam for assembling a repercussion of designing added substances. Erosion mix (FSW) is a solid nation welding procedure changed into as of late advanced to beat the issues experienced in combination welding. This procedure utilizes a non-admission gadget to produce frictional warmth at the outside of a fringe. Welding parameters, which incorporates stick profile apparatus, the rotational speed, the welding pace and the hub pressure, plays a main situation in making sense of the shape and microstructure of the consumption opposition of welded joints. In this work the applicable composite design with speeds, explicit cross pace and Four rigging had been utilized to limit exploratory situations.

Synthesis of Pseudoboehmite - Aging Effect

The Pseudoboehmite is an aluminum compound used as an alumina precursor and it is produced by sol-gel process. The sol-gel process is a methodology to produce porous, vitreous or crystalline ceramics started by molecular precursors. Pseudoboehmite with high purity, high specific surface area and porous homogeneity was obtained by sol-gel process. The material was used to produce gamma-alumina with surface area ranging from 211.2-288.1m2/g. It was studied the effect of aging time, temperature of aging and poly (vinyl alcohol) addition in the synthesis.