Sharif Digital Repository

Red grape skin has a lot of antioxidant that called Anthocyanins. In this research this material has been studied and amount of extraction of them have been studied by changing the operational parameter and particle size in taguchi procedure. Pressurized liquid extraction (PLE) was used to extract Anthocyanins from Dried Red Grape Skin (DRGS) with acidified Ethanol solvent (1 %( v/v) of HCl) in 90-120°C, 10-40 bar, and 30 min extraction time. In this study, effect of particle size distribution of DRGS was considered and the results showed that with increasing the temperature (from 90 to 120 °C in 10 °C increments) and decreasing the pressure and particle size the extraction of Anthocyanins... 

Milk is One of the most important source s of protein in the world. during the process of cheese the most of these protein remain in whey. There are different methods to separate these protein from whey. The one of advanced method is ultrafiltartion, this method is based on a permeable membranes, with different pore size. There are many research works in this field. In this project we have tried to study the effect ofpressure, temperature, concentration and resistance time on membrane porosity. In order to design the experiment and analyze the results tagochi L 16 methods is used. The PVC membranes were prepaid by gas anti solvent method, experiment showed that changes of temperature and... 

One of the most convenient methods for the synthesis of metal oxide nanoparticles, inorganic ceramic materials and catalysts is supercritical hydrothermal method. In its pure form or mixed metal oxide nanoparticles have potential applications are wide. An important aspect of functional metal oxides of uranium dioxide as the selective catalyst for the conversion of methane to methanol and chlorinated organic matter decomposition is used. The main issue that led to the definition of this project was that nanoparticles synthesized with supercritical hydrothermal conditions influenced by change in the temperature. Temperature also affects the particle size and the conversion efficiency. This... 

Transonic flow study is important due to its vast applications. Supercritical airfoils are designed for transonic flow to postpone drag divergence and reduce the strength of shock. This type of airfoils are chiefly used in modern commercial airplanes because of their low drag in transonic regime and, as a result, reduction in their fuel consumption. Using supercritical airfoils needs accurate investigation of flow field due to several influential factors such as specific geometry, nonlinear nature of flow phenomena, and compressibility effects. However, the availability of experimental and numerical data for supercritical airfoils is less than that of the conventional ones. Thus,... 

A ten percent thick supercritical airfoil, having special previllage rather than conventional airfoils tested in a low speed wind tunnel to measure pressure distribution over the airfoil in steady and unsteady flow. Present thesis is set out to discuss effects of reduced frequency and mean angle of attack on pressure distribution during plunging motion in low-subsonic flow. Investigation of experimental data from frequency domain aspect is very challenging area in experimental aerodynamics. Therefore, the concepts of frequency domain analysis is pointed out. The analysis of experiment data is devidind in two different part, that is, steady and unsteady flow. Flow separation over the airfoil... 

Green chemistry seeks to reduce or eliminate the use of hazardous substances in the chemical industry through the development of new products and processes .The replacement of harmful, widely used solvents and reagents is a key part of this approach. Supercritical fluid such as CO2 or water are good solvent for replaceement Exchange reactions involving the displacement of hydrogen bonded to carbon by deuterium are of interest in a broad variety of disciplines, such as the preparative chemistry of isotopically labeled materials, fundamental studies of carbonehydrogen bond activation processes, and studies of the nature of catalysts. The low cost of water and its environmental friendliness... 

Supercritical airfoils are designed for transonic flow to reduce the strength of shock and its drag. These type of airfoils are used in design and construction of commercial airplanes because of their low drag in transonic regime and, as a result, a reduction in fuel consumption. Using supercritical airfoils needs accurate investigation of flow field due to several influential factors such as their specific geometry, nonlinear nature of flow phenomena, and compressibility effects. However, the availability of experimental and numerical data for supercritical airfoils is less than that for conventional airfoils. Thus, conducting experimental tests is essential for understanding of flow field... 

Combustion in supercritical conditions (thermodynamic) is one of the most important applications of today's systems. One of the reasons for the increased use of combustion in supercritical conditions is the need to develop high pressure combustion systems, such as liquid fuel engines, gas turbines and internal combustion engines. Combustion is a technique in which the fuel is injected into the combustion chamber with its supercritical state (Any substance at a temperature and pressure above its critical point). Fuels in the supercritical conditions exhibit new features such as low viscosity, high diffusivity and low surface tension, which lead to higher efficiency, high power generation and... 

Thermodynamic properties of supercritical carbon dioxide change near the critical point. High cycle efficiency is realized by having the main compressor to operate near the critical point of CO_2 to benefit from reduced compression work. In addition the high efficiency, compactness, nontoxicity, cheap working fluid and possibility of using dry cooling instead of wet cooling, s-CO_2 has many application such as nuclear, fossil fuel, renewable sources like solar thermal and waste heat. With regards to sCO_2 thermodynamic properties, suitable equation of state with high accuracy has been determined, and then is used in the design modeling. Recompression Brayton cycle with steady state flow is... 

Supercritical airfoils have been designed for transonic flow, however due to different flight conditions, the airfoil behavior during take-off and landing of the aircraft in subsonic flow regime must be known. Experimental and numerical information derived from supercritical airfoils are less than those of conventional airfoils. Because of the special geometry of supercritical airfoils and different phenomena that occurs through flow, using such airfoils even in steady states requires precise study/analysis of the flow. Therefore, one could benefit from experimental tests to better understand flow phenomena. The objective of the present research is the study effect of mean angle of attack... 

Although CO2 is an environmentally benign solvent, many organic solutes are only sparingly soluble in CO2. We use Monte Carlo simulations in the context of statistical perturbation theory, Widom’s particle insertion and expanded ensemble techniques in order to investigate the molecular properties involved in enhancing the solubility of materials in CO2. Our Monte Carlo simulation of diluted methane and its fluorinated forms showed that substitution of H atom with F atom, results in more favorable solvation, but with further increase of F atom (after CH2F2) due to small size of solute it is impossible for all CO2 molecules in the first solvation shell (FSS) to have a good orientation against... 

Green tea has been receiving significant attention in recent years due to its high content of catechins; Epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and especially epigallocatechin gallate (EGCG). As powerful antioxidants, these compounds are believed to have several health benefits. In this study, we used supercritical CO2 with ethanol as co-solvent to extract catechin derivatives from green tea and we investigated the effects of experiment parameters on the extraction. Experiments, designed according to Taguchi algorithm, were conducted with green tea particles of four average diameters of 1500, 855, 605 and 427.5 µm, in an interval of 35- 55 ̊C for temperature and... 

Juglone is a naphthoquinone compound which is found in all parts of a walnut tree; including the leaf, root, walnut green husk, and bark. It is mostly used in dyeing industries. In this study, Juglone pigment is extracted from walnut husk by using the supercritical CO2 and Ethanol as a co-solvent, and the effects of parameters such as temperature, pressure, and size of husk particles on extraction efficiency are studied. The experiments have been designed based on Taguchi algorithm. Temperature and pressure range are chosen to be 35-50°C and 90-150 bar respectively. Walnut husk particles have been prepared dry from the city of Torbat Heidarieh in different average diameters; 1500, 855, 605... 

In this research, we focused on demonstration of features and advantages of supercritical fluids technology to formation of fine particles (nano and micro scales) from bulk materials (solid) and synthesized metal oxides nanoparticles. Therefore, using two different fluids, carbon dioxide and water, and two completely different methods, the Rapid expansion of supercritical solution and supercritical hydrothermal, were used to produce fine particles of drug (acetaminophen) and nano metal oxide (zirconium dioxide and bismuth ferrite). The summary of this research are as follows:1. The solubility of acetaminophen in SuperCritical-Carbon Dioxide (SC-CO2) with and without menthol as a cosolvent... 

Transonic flow study is important due to its vast applications. Supercritical airfoils are designed for transonic flow to postpone drag divergence and reduce the strength of shock. This type of airfoils are chiefly used in modern commercial airplanes because of their low drag in transonic regime and, as a result, reduction in their fuel consumption. Using supercritical airfoils needs accurate investigation of flow field due to several influential factors such as specific geometry, nonlinear nature of flow phenomena, and compressibility effects. However, the availability of experimental and numerical data for supercritical airfoils is less than that of the conventional ones. Thus,... 

Hydrothermal supercritical method is one of the most suitable methods for metal oxide nano powder, ceramics and mineral catalyst synthesis. Metal oxides nanopowder in its pure or mixed form has wide potential application as chemical industrial catalyst, hot Superconductors, magnetic material, gas sensors and car catalyst convertors. One of the most important metal oxides aspects of application is uranium oxide as nuclear reactor fuel is used. In addition, UO2 is selective catalyst for converting methane to methanol process and Decomposition of organic Chlorine material. In Supercritical hydrothermal method done in high pressure reactor with critical to fluid, is new method for the... 

I-131 isotope is one of the most significant radio medicines for treatments of the thyroid cancer and nuclear tomography of thyroid. As for purification of this radioisotope several methods have been developed among which adsorption-desorption on metallic copper is the most promising. The current study is aimed at elaboration of the kinetics behavior of the different types of metallic copper for adsorption of iodine vapor. The used copper samples included plain and silica-supported Cu nanoparticles as well as micronized copper. The silica-supported Cu nanoparticles were prepared by impregnation of highly porous silica (≈500 m2/g) in Cu(NO3)2 solution, heating of the solution to above... 

Graphene is pure carbon in the form of a very thin, nearly transparent sheet, one atom thick. It is remarkably strong for its very low weight. Graphene is a novel particle that can improve adsorption properties. We use graphene for Iodine gas adsorption. Iodine-131 (usually in the chemical form of iodide) is a component of nuclear fallout, and is particularly dangerous owing to the thyroid gland's propensity to concentrate ingested iodine, where it is kept for periods longer than this isotope's radiological half-life of eight days. For this reason, if people are expected to be exposed to a significant amount of environmental radioactive iodine (iodine-131 in fallout), they may be instructed... 

Nuclear power is a prominent alternative of fossil fuels that can effectively solve global warming, acid rains and other consequences of air pollutions, caused by combustion. Despite such obvious advantage, this highly compact form of energy suffers from a big problem corresponding to its nuclear waste. Graphene oxide (GO), a lamellar material with wide range of surface functional groups such as epoxy (C-O-C), hydroxyl, and carboxyl offers large surface area as well as high sorption capacity for the metallic cations. This thesis study presents a supercritical, and co-precipitation synthesis of magnetite- graphene oxide (M-GO) in which Fe3O4 nanoparticles are simultaneously formed, surface... 

In this study the kinetics of extraction of various hydrocarbons from crude oil using supercritical CO2 has been studied experimentally. The effect of parameters such as temperature (35, 45, 55, 65 °C), pressure (90, 110, 130, 150 bar), initial volume of crude oil (16, 19, 22, 25 mL) were investigated. Flow rate of gas has been recorded dynamically. QUALITECH 4 and MATLAB neural network softwares have been used for designing the experiments and modeling the final results, respectively. Pressure has a direct effect on extraction yield and by increasing it, heavier fractions could be obtained. On the other hand, the effect of temperature is more complicated, by increasing the temperature, the...