Simulation of The Heat Transfer Process Inside The Thatch Walls with The Aim of Saving Energy in The Buildings

The insulation is one of the emphasized methods in recent years to reduce energy consumption in buildings. As an insulator, thatch has the advantages such as the accessibility of the site, the least energy consumption in its construction (low cost), recyclability and compatible with the nature and the environment. The aim of this study is determining of the heat transfer coefficient and thatch mechanical properties So that due to its advantages it used as insulation and thereby reducing energy consumption in buildings considered and used. In this study, the heat transfer process in a cylindrical turn of thatch was studied. In the conducted experiments the temperature changes inside a cylinder turn were determined for different values of the ratio of the Straw to the used soil and then the obtained results were simulated using the version 2.4 of the COMSOL software. The compressive strength and mechanical properties of thatch were tested. By increasing the consumed Straw weight of 50 to 90 kg per 1 cubic meter of soil, the heat conductivity coefficient from about 1.1 decreased to about 0.3 (W/m K), the contraction percentage decreased and the porous, the compressive strength and the thatch deformability increased in the failure. Thermal insulation and the mechanical properties of the thatch were improved by the mixing of appropriate ratio of straw to soil in the construction of thatch. It can be used in the plaster of the walls and the internal and external ceilings of the building

Experimental investigation and numerical modeling of carbon dioxide desorption from activated carbon vessel by using of finite elements method

Adsorption and desorption of substances in the surface of adsorbent materials are very important in various chemical industries. In this work, at first, desorption of carbon dioxide on activated carbon fixed bed were examined, then by using of a two dimensional geometry and finite elements method with COMSOL multiphysics software the desorption phenomena were simulated numerically. By using of the proposed numerical model the effects of some effective parameters were studied theoretically. Modeling of activated carbon fixed bed was performed for two fixed and mobile phases in the bed and in stationary and time dependent regimes. Based on the reported results in this work, the mass transfer coefficient and the outlet flux of carbon dioxide from the particles of bed are effective parameters on the desorption phenomenon

Removal of Cobalt Ions from Contaminated Water Using Magnetite Based Nanocomposites: Effects of Various Parameters on the Removal Efficiency

Cobalt is one of the most hazardous heavy metals present in the environment. Magnetic based nanoadsorbents were used for removal of Co(II) ions in this work. The characteristics results of FT-IR, XRD, TGA, and FE-SEM show that applied coatings were modified magnetite nanoparticles efficiently. The results of TEM indicate that magnetic nanoadsorbents were produced on the nanoscale with average particle sizes of 60±10 nm. Batch experiments were carried out to determine the removal efficiency of the nanoadsorbents. pH, temperature, contact time, adsorbent dose, shaking rate and the initial concentration of analyte were the studied parameters. At optimized conditions of operation parameters, the maximum removal percentage of 92% was obtained by using magnetite-citric acid as an adsorbent. Equilibrium data for Co(II) ions adsorption onto magnetite-citric acid were fitted well by Langmuir isotherm model and the maximum adsorption capacity for Co(II)ions was obtained 43.292 mg/g at 313 K. Also, thermodynamic parameters reveal the spontaneity, feasibility and endothermic nature of the Co(II) ions adsorption process. In addition, the cobalt ions can be desorbed from magnetite-citric acid nanoadsorbent by using nitric acid solution with 95% desorption efficiency and the magnetite-citric acid nanoadsorbent exhibits good recyclability

MATHEMATICAL MODELING FOR RAPID EXPANSION OF SUPERCRITICAL SOLUTION TO PRODUCE NANO AND MICRO NABUTEMON PARTICLES

A new model is proposed for production of fine particles of Nabutemon by rapid expansion of supercritical solutions (RESS). A mathematical model is used for prediction of particle size and particle size distribution of RESS produced particles. In this model the effect of various operating parameters such as pressure and temperature of extraction and temperature and pressure of expansion on the characteristics of products were studied. The calculation results showed good agreement between the calculation results and the experimental data for Nabutemon particles

Separation of Propionic Acid from Aqueous Solution by Solvent Extraction

The precise Liquid - liquid equilibrium (LLE) data are needed and required in design of many chemical processes, separation operations, and fermentation industry. In this research, (LLE) data for (trichloroethylen + propionic acid + water) were determined at atmospheric pressure and 300.15 K. LLE phase diagram was obtained for this ternary system. The distribution coefficients and the selectivity factors of the solvent were calculated. It can be seen that the separation factor values decrease from 10.55 to 4.317 with increasing propionic acid weight fraction in aqueous phase from 0.06 to 0.4

Separation of Propionic Acid from Aqueous Solution by Solvent Extraction

The precise Liquid - liquid equilibrium (LLE) data are needed and required in design of many chemical processes, separation operations, and fermentation industry. In this research, (LLE) data for (trichloroethylen + propionic acid + water) were determined at atmospheric pressure and 300.15 K. LLE phase diagram was obtained for this ternary system. The distribution coefficients and the selectivity factors of the solvent were calculated. It can be seen that the separation factor values decrease from 10.55 to 4.317 with increasing propionic acid weight fraction in aqueous phase from 0.06 to 0.4

Chemical Composition and Antioxidant Activity of Extracts from the Fruit, Leaf, and Branchlet of Cupressus arizonica Greene

Potent antioxidant activities of solvent extracts (96% aqueous ethanol) from the fruit, leaf, and branchlet without adherent leaf of Cupressus arizonica were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and compared with butylated hydroxytoluene (BHT) and ascorbic acid (AA). Their chemical compositions were analyzed using gas chromatography-mass spectrometry (GC/MS). Branchlet extracts (BE) were the most active as an antioxidant agent at 93.3% at the concentration of 0.493 mg/mL, which was higher than the value of vitamin C (63.3%) at the same concentration. The major components identified in the BE were communic acid (43.7%), followed by agatholic acid (20%), and ferruginol (10.4%). The extract from fruit had good antioxidant activity (90.3%) at a concentration of 0.015 mg/mL. The major compounds identified in the fruit extracts (FE) were communic acid (46.8%), spirohexane-5-carboxylic acid, 1,1,2,2-tetramethyl-, methyl ester (27.4%), and ferruginol (6%). Leaf extracts (LE) were more active as an antioxidant agent at 80.3%, which was higher than the value of BHT (75.7%) at the concentration of 0.015 mg/mL. The major components identified in the LE were hexadecanoic acid (45.1%), 1H,5H-pyrrolo[1',2':3,4]imidazo[1,5-a]pyridine, octahydro- (9%), bicyclo [3.1.0]hex-3-en-2-one, 4-methyl-1-(1-methylethyl)- (8.1%)

Examining the stages of nanopowder production using the sol-gel method

در این مقاله مراحل تولید نانو ذرات با روش sol-gel بررسی شده و سازوکارهای های پیشنهادی برای این فرایند، ارائه شده است. هم چنین شرایط عملیاتی و نوع حلال ها و مواد به کار رفته در این فرایند ها، برای تولید نانو پودر های مورد نیاز در صنعت آورده شده است. اثرات این حلال ها بر خصوصیات محصولات تولیدی نیز بررسی شده است. مراحل مختلف مورد نیاز برای تولید نانو متال فلوراید های AlF3 و MgF2 ، نانو کامپوزیت Al2O3-ZrO2 ، نانو متال اکساید TiO2 و TiO2 متصل شده به منیزیم و باریم، مختصر ﴽ توضیح داده شده است

Thermodynamic modeling of solid solubility in supercritical carbon dioxide: Comparison between mixing rules

In this paper, Peng Robinson equation of state is used for thermodynamic modeling of the solubility of various solid components in the supercritical carbon dioxide. Moreover, the effects of three mixing rules of Van der Waals mixing rules, Panagiotopoulos and Reid mixing rules and modified Kwak and Mansoori mixing rules on the accuracy of calculation results were studied. Good correlations between calculated and experimental data were obtained in the wide temperature and pressure range. A comparison between used models shows that modified Kwak and Mansoori mixing rules give better correlations in comparison with the other mixing rules

Mechanisms of nano powder Production by means of sol-gel route

In this work production of nano powders by means of sol-gel route were reviewed. Proposed mechanisms, required materials such as solvents or solutes that used for production of industrial nano powders and the effects of them on the characteristics of products were evaluated. Various processes that used for production of nano metal fluorides such as AlF3 and MgF2, nano composites such as Al2O3-ZrO2 and nano metal oxides such as TiO2 and TiO2 adapted to Mg2+ and Br2+ were also reviewed