Search for: evaporation
Total 170 records
Preparation of ethyl cellulose microcapsules containing perphenazine and polymeric perphenazine based on acryloyl chloride for physical and chemical studies of drug release control [electronic resource], Article Polymer International ; Volume 47, Issue 4, pages 413–418, December 1998 ; Pourjavadi, A ; Hashemi, S. A ; Arabi. , H ; Sharif University of Technology
The preparation of microcapsules containing perphenazine by solvent evaporation using ethyl cellulose is described. The microparticles are formed after solvent evaporation and polymer precipitation. The drug was dissolved in a polymer solution and emulsified into an aqueous phase to form microcapsules. To study the effects on particle size, encapsulation efficiency and morphology, three different molecular weights of ethyl cellulose (Mw=47000, 71000 and 99000) were used. Covalent bonding of drugs to polymers via hydrolytically or enzymatically cleavable covalent bond was achieved for sustained drug delivery. The release rate of perphenazine from these systems was investigated
Effects of wax boundaries in combination with evaporation on dynamics of fluid flow in paper-based devices, Article Surfaces and Interfaces ; Volume 21 , 2020 ; Shamloo, A ; Sharif University of Technology
Elsevier B.V 2020
Since their introduction, paper-based microfluidic analytical devices (μPADs) have been ubiquitously utilized for different applications. The spontaneous imbibition of liquids in the paper-based devices that eliminates the requirement of an external pumping system has played a primary role in making paper an appropriate alternative for many other materials in the fabrication of microfluidic devices. Wax patterning is one of the most common methods to fabricate μPADs. Dynamics of the flow in channels with wax boundaries deviate from Washburn's law. Despite some research performed to model the effects of wax boundaries, some gaps remain in the presented models. A more general model is needed...
M.Sc. Thesis Sharif University of Technology ; Alamolhoda, Ali Asghar ; Hashemian, Jamaledin
The mechanical spray evaporator (MSE) is a method of enhanced evaporation technology, normally designed to reduce the particle size of a wastewater droplet to volatilize water content of it as quickly as possible. A model of MSE has been built at the Institute of Water and Energy at Sharif University of technology. The aim of this research is to study the efficiency of enhanced evaporation technology for waste disposal. To achieve the accurate results, the required pumping rates and power consumption, sustained evaporation rates while operating the fans, and the performance during various temperature, wind speed and relative humidity, are required. Mechanical Spray Evaporator technique...
An innovative solar assisted desiccant-based evaporative cooling system for co-production of water and cooling in hot and humid climates, Article Energy Conversion and Management ; Volume 185 , 2019 , Pages 396-409 ; 01968904 (ISSN) ; Roshandel, R ; Vakiloroaya, V ; Sharif University of Technology
Elsevier Ltd 2019
Although evaporative coolers consume much lower electricity than the vapor compression systems, they are not applicable in humid climates. Combination of desiccant wheels and evaporative coolers, known as desiccant-based evaporative cooling systems, allows evaporative coolers to be used in humid climates, which provide significant energy and environmental advantages with respect to vapor compression systems. However, one of the main disadvantages of evaporative cooling is the high water. Regarding the global water crisis, a cooling system which saves both water and energy will be an attractive alternative to the current cooling systems. To this aim, this paper presents a novel...
M.Sc. Thesis Sharif University of Technology ; Nouri Borujerdi, Ali
Two-phase flows are widely used in petrochemical industry, chemical processes, boilers, nuclear reactors, cooling systems and air conditioning equipment. Since the problem of earth’s ozone layer and global warming, the analysis of flow characteristics in evaporators are necessary to improve performance of refrigerating systems and saving the environment. Most of the researchers have been studied the evaporation of two phase flow refrigerant through experimental studies and numerical analysis has less attention in the literature. In this Thesis, a mathematical model based on the two-phase separated flow model is developed to simulate the evaporation of pure refrigerant under constant heat...
Multilayer evaporation of MAFAPbI3-xClx for the fabrication of efficient and large-scale device perovskite solar cells, Article Journal of Physics D: Applied Physics ; Volume 52, Issue 3 , 2019 ; 00223727 (ISSN) ; Yadav, P ; Prochowicz, D ; Tavakoli, R ; Saliba, M ; Sharif University of Technology
Institute of Physics Publishing 2019
FAPbI3 perovskites are excellent candidates for fabrication of perovskite solar cells (PSCs) with high efficiency and stability. However, these perovskites exhibit phase instability problem at room temperature. In this work, to address this challenge we use methylammonium chloride (MACl) as an additive and employed a layer-by-layer thermal evaporation technique to fabricate high-quality perovskite films on a large scale of 25 cm2. The optimized perovskite films show high crystallinity with large grains in the μm-range and reveals phase stability due to the presence of MACl after the annealing process. Finally, we achieved PSCs with 17.7% and 15.9% for active areas of 0.1 cm2 and 0.8 cm2,...
Effect of working fluid inventory and heat input on transient and steady state behavior of a thermosyphon, Article Journal of Thermal Analysis and Calorimetry ; Volume 143, Issue 5 , 2021 , Pages 3825-3834 ; 13886150 (ISSN) ; Forootan, D ; Farajimoghaddam, F ; Sharif University of Technology
Springer Science and Business Media B.V 2021
The effect of working fluid inventory and heat input on the performance of thermosyphon is investigated in this paper. First, a thermosyphon with diameter of 16 mm made of steel with toluene as working fluid and the length of the evaporator, adiabatic and condenser section 10, 23 and 17 cm was considered, respectively. The working fluid inventory was considered 0.1, 0.14, 0.18 and 0.24 of total volume of thermosyphon and in each case 54–235 W of heat input applied to the evaporator area also. In order to evaluate the transient behavior of the thermosyphon, in any amount of working fluid, 28 W of heat input was considered and temperature of the evaporator area were recorded at different...
M.Sc. Thesis Sharif University of Technology ; Tajrishy, Masoud ; Irajizad, Azam
Reducing water evaporation is one of the ways to overcome the low precipitation and drought conditions in water reservoirs. For this purpose, extensive studies have been investigated on physical and chemical coatings on lakes and reservoirs. Physical methods often involve the use of floating covers on the water surface to block evaporation by shading, most of which are only suitable for reservoirs with surface areas smaller than 5 hectares. In chemical methods, the evaporation can be decreased by nanomaterial coating, usually, containing long-chain molecules, which by spraying them on the surface, molecular monolayers are formed. In this study, the effect of nanometer coatings on the surface...
M.Sc. Thesis Sharif University of Technology ; Nouri Boroujerdi, Ali ; Hosseini, Vahid
In the leading thesis, an attempt is made to improve the evaporation rate by emphasizing the reduction of heat transfer to the fluid bulk. In this study, inspired by the process performed in plants in the transfer of water from the roots to the leaves and especially the function of plant vessels, a kind of evaporator-improving surface was designed. The general function of this surface is to prevent the heat radiated to the surface of the water from being spent on heating the fluid deep in the water, and by concentrating this heat in a thin layer of fluid on the surface, the rate of evaporation increases. This surface consists of three parts: evaporative layer, insulation and water suction...
Article Applied Physics A: Materials Science and Processing ; Volume 97, Issue 2 , 2009 , Pages 361-364 ; 09478396 (ISSN) ; Janfeshan, B ; Sadrnezhaad, Kh ; Sharif University of Technology
One-dimensional nanostructures of tin oxide nanotubes were fabricated by carbothermal evaporation at 900°C in air. The synthesized film was grown on Au-coated (100) Si substrate. Heterogeneous catalysis by Au/Sn droplets assisted the formation of the tin oxide nanotubes of less than 40 nm diameter at Sn vapor pressures around 1.4×10 -7 Pa. In order to reduce the nanotube diameter further, an increase in the Sn vapor pressure by changing the source materials' ratio seemed viable. © 2009 Springer-Verlag
Influence of coloring voltage and thickness on electrochromical properties of e-beam eaporated W O3 thin films, Article Journal of the Electrochemical Society ; Volume 153, Issue 2 , 2006 , Pages E11-E16 ; 00134651 (ISSN) ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
In this investigation, the effect of coloring voltage and thickness on optical and also electrochromical properties of W O3 thin films has been studied. The W O3 thin films were grown on glass and indium tin oxide coated conducting glass substrates by e-beam evaporation at different thicknesses of 200, 400, and 700 nm. Optical properties of the deposited samples were characterized in the ultraviolet-visible range (300-1100 nm). The optical bandgap energy of the W O3 was obtained in a range of 3.3-3.5 eV showing its increase by decreasing the film thickness. The refractive index of the W O3 films was measured around 2 in the visible range. Surface chemical states of the films were studied by...
Selection of prime mover to meet heating demand of a single effect absorption chiller based on laws of thermodynamics, Article SN Applied Sciences ; Volume 3, Issue 1 , 2021 ; 25233971 (ISSN) ; Saidi, M. H ; Najafi, M ; Aghanajafi, C ; Sharif University of Technology
Springer Nature 2021
In this study the first and the second laws of thermodynamics are evaluated for a single effect absorption chiller. Entropy generation and COP are selected as the objective functions and their variations are studied by varying the generator temperature for various condensing temperatures. For this purpose, the enthalpy and the entropy data of the super-heated steam, saturated steam and the saturated water are formulated in the mathematical equations. Also to provide the required steam of generator, prime mover in the form of internal combustion engine is applied and its partial load conditions are analyzed. A residential tower is considered as the case study for selecting the proper prime...
M.Sc. Thesis Sharif University of Technology ; Arfaei, Hesammeddin
When we consider Klein-Gordon and Maxwell perturbation fields on the constant gravitational background, the Einstein-Maxwell equations solution will lead to Reissner-Nordstrom black hole which has decreasing mass because of Hawking radiation of bosons from its outer horizon; by reaching this balck hole to extremal case the evaporation will be stoped. The evaporation time is infinite. But String theory equations solution in General Relativity approximation shows that  if a Dilaton field ϕ has a exp(-αϕ) coupling with electromagnetic field, the rate of reaching to extremal case will depend on α. We show that by increasing α from 0 to 1, the evaporation time will be initially infinite...
M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem
The study of evaporation of fuel droplet and determination of the rate of vaporization are important in designing combustion chambers. For achieving high performance of a combustor, the evaporation of fuel droplets takes place within a high pressure environment. At these conditions, the use of low-pressure models is not appropriate and many effects that are assumed negligible at low ambient pressures become very important. For example, the solubility of the ambient gas into the liquid phase is increased by increasing the ambient pressure. In addition, the ideal gas assumption is not valid for these conditions and one should use an appropriate equation of state (EOS) that can predict the...
M.Sc. Thesis Sharif University of Technology ; Kariminia, Hamid-Reza ; Borghei, Mehdi
Odor caused by the release of volatiles from refinery waste, causing environmental pollution and health hazards may occur. Refinery wastewater project in Saeakhs (Khangiran) has been studied. Contaminated water in evaporation ponds at the plant accumulates due to the large volume of incoming water and slow evaporation in summer the water will smell unpleasant. Odor from the ponds due to wind scattered around the refinery and residents will be put at risk. Several tests to identify the source of the odor was designed and implemented. Among these methods, microalgae growth, the import of oil products such as aromatic compounds or mercaptans, and bacterial growth, for each of the hypotheses...
M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali
Evaporation and condensation of thin films can rupture or stabilize thin film .We show that evaporation hastens dewetting of a thin film. Dewetting over nanometric downward step causes pinning of the contact line near the step. This phenomena is not permanent and after certain time that contact angle reaches to its critical value depinnnig happens. We also study the effect of the step size, contact angle, film thickness, slip and evaporation on the depinning time of the contact line. We show that depinnig time has a reverse relation with the rate of evaporation
Novel dual-loop bi-evaporator vapor compression refrigeration cycles for freezing and air-conditioning applications, Article Applied Thermal Engineering ; Volume 138 , 25 June , 2018 , Pages 563-582 ; 13594311 (ISSN) ; Rostamzadeh, J ; Matin, P. S ; Ghaebi, H ; Sharif University of Technology
Elsevier Ltd 2018
Cooling production at different temperature levels for various applications has been highlighted in recent years since the produced cooling capacity must be used for different applications to meet all subjects’ demands. For this purpose, a novel dual-loop bi-evaporator vapor compression refrigeration cycle is proposed to meet these demands for freezing and air-conditioning applications which can be employed in building sectors. Later, ejector expander is used in place of the expansion valve in the proposed refrigeration system to enhance the performance of this basic system based on the thermodynamics and thermoeconomics viewpoints. Four working fluids of R717, R290, R600a, and R134a are...
Incorporation of new technique for processing of Al/SiCp composites based on evaporative pattern casting (EPC) method, Article Materials Science and Technology ; Volume 24, Issue 7 , 2008 , Pages 809-814 ; 02670836 (ISSN) ; Bagheri, R ; Sadeghian, M. H ; Sharif University of Technology
A336 Al matrix composites containing different volume fraction and mean mass particle size of SiC particles as the reinforcing phase were synthesised by evaporative pattern casting (EPC) route. The process consisted of fabricating of EPS/SiCp composite pattern followed by EPC of A336 Al alloy. The EPS/SiCp pattern was made by blending SiC particles with expandable polystyrene (EPS) beads and placing them in expanding mould heating with steam until EPS beads expand completely. Uniform distributed SiC particles around the EPS beads and locally movement of them during pouring and degradation leads to homogenous distribution of particles in final Al/SiCp composite. Higher modulus, strength and...
Article Physica Status Solidi C: Conferences ; Volume 1, Issue 7 , 2004 , Pages 1744-1747 ; 16101634 (ISSN) ; Sangpour, P ; Sharif University of Technology
To investigate the Ta/Co/Cu/Co/NiO/Si(100) spin valve structure, fabrication and characterization of the Cu/Co/NiO/Si(100) system was studied for further understanding the structure. The system was grown by employing combinative DC sputtering-evaporation technique. Nickel oxide with a thickness of about 30 nm was deposited on Si(100) substrate using thermal evaporation technique.The cobalt film, then, with a thickness of about 3 nm was grown by DC sputtering under various applied negative bias voltages ranging from 0 to - 80 V. The optimum bias voltage (Vb = -60 V) for the growth of Co layer was determined by atomic force microscopy (AFM), four-point probe sheet measurement (Rs) and scanning...
Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 23, Issue 2 , 2004 , Pages 45-53 ; 10219986 (ISSN) ; Sabzyan, H ; Zeini Isfahani, A ; Parsafar, G ; Sharif University of Technology
Iranian Journal of Chemistry and Chemical Engineering 2004
In this work, a more accurate prediction of liquid evaporation flux has been achieved. The statistical rate theory approach, which is recently introduced by Ward and Fang and exact estimation of vapor pressure in the layer adjacent to the liquid-vapor interface have been used for prediction of this flux. Firstly, the existence of an equilibrium layer adjacent to the liquid-vapor interface is considered and the vapor pressure in this layer and its thickness calculated. Subsequently, by using the Fick's second law, an appropriate vapor pressure expression for the pressure of equilibrium layer is derived and by this expression and the statistical rate theory approach, evaporation flux is...