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Investigation of a radiative sky cooling module using phase change material as the energy storage
, Article Applied Energy ; Volume 321 , 2022 ; 03062619 (ISSN) ; Khalilmoghadam, P ; Behshad Shafii, M ; Moshfegh, A. Z ; Hu, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Radiative sky cooling (RSC) systems have enjoyed a privileged position in the research community due to generating cooling energy without consuming electricity using the open atmospheric window and infrared emission to the sky. However, the system's justification occurs when it reaches a temperature below the minimum 24-hour ambient temperature. This study utilizes phase change materials (PCM) as the energy storage of a hybrid daytime photovoltaic-thermal and nighttime RSC module and investigates the nocturnal cooling energy-saving potential of the system at different phase transition temperatures. After being validated by the experimental data in the literature, the simulated model was used...
The effect of non-uniform magnetic field on the efficiency of mixing in droplet-based microfluidics: a numerical investigation
, Article Micromachines ; Volume 13, Issue 10 , 2022 ; 2072666X (ISSN) ; Nouri, M ; Hassani Gangaraj, M ; Shamloo, A ; Nasiri, R ; Sharif University of Technology
MDPI
2022
Abstract
Achieving high efficiency and throughput in droplet-based mixing over a small characteristic length, such as microfluidic channels, is one of the crucial parameters in Lab-on-a-Chip (LOC) applications. One solution to achieve efficient mixing is to use active mixers in which an external power source is utilized to mix two fluids. One of these active methods is magnetic micromixers using ferrofluid. In this technique, magnetic nanoparticles are used to make one phase responsive to magnetic force, and then by applying a magnetic field, two fluid phases, one of which is magneto-responsive, will sufficiently mix. In this study, we investigated the effect of the magnetic field’s characteristics...
Learning-Oriented QoS- and drop-aware task scheduling for mixed-criticality systems
, Article Computers ; Volume 11, Issue 7 , 2022 ; 2073431X (ISSN) ; Alikhani, H ; Safaei, B ; Ejlali, A ; Kumar, A ; Sharif University of Technology
MDPI
2022
Abstract
In Mixed-Criticality (MC) systems, multiple functions with different levels of criticality are integrated into a common platform in order to meet the intended space, cost, and timing requirements in all criticality levels. To guarantee the correct, and on-time execution of higher criticality tasks in emergency modes, various design-time scheduling policies have been recently presented. These techniques are mostly pessimistic, as the occurrence of worst-case scenario at run-time is a rare event. Nevertheless, they lead to an under-utilized system due to frequent drops of Low-Criticality (LC) tasks, and creation of unused slack times due to the quick execution of high-criticality tasks....
Analytical and numerical study on droplet breakup in microfluidic T-junction
, Article Chemical Engineering and Processing - Process Intensification ; Volume 177 , 2022 ; 02552701 (ISSN) ; Moosavi, A ; Hannani, S. K ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Droplet breakup in symmetric T-junctions is one of the important phenomena in droplet microfluidics. Many studies have been done about the droplet breakup but none of them has provided a general analytical solution for the droplet breakup. In this study, we present an analytical solution to investigate the effect of important parameters such as the capillary number, droplet length, and channel widths ratio. The analytical solution is validated using the numerical simulation. Using the analytical equation and numerical results, we propose a generalized relationship. This general equation can be used as a rule of thumb for droplet breakup predictions with high accuracy. The results indicate...
Developing an Off-the-Shelf microfluidic droplet generation device for cell encapsulation
, Article Industrial and Engineering Chemistry Research ; Volume 61, Issue 30 , 2022 , Pages 10689-10699 ; 08885885 (ISSN) ; Shamloo, A ; Sharif University of Technology
American Chemical Society
2022
Abstract
Droplet microfluidics is a platform of microfluidics in which two immiscible fluids are used to generate droplets for various biomedical applications. This platform introduces several advantages in applications such as cell lysis, cell culture, co-culture, and cell encapsulation. The most important issues regarding droplet generation devices are the fabrication complexity and maintenance of these devices. In this study, a simple and easy-to-fabricate microdroplet generator is designed and fabricated to resolve these issues. Furthermore, since this device is easy to fabricate and use, it can play a key role in the fabrication of medical devices for controlling infectious diseases in poor and...
Droplet-based microfluidics in biomedical applications
, Article Biofabrication ; Volume 14, Issue 2 , 2022 ; 17585082 (ISSN) ; Besanjideh, M ; Nasiri, R ; Shamloo, A ; Nasrollahi, F ; De Barros, N. R ; Davoodi, E ; Erdem, A ; Mahmoodi, M ; Hosseini, V ; Montazerian, H ; Jahangiry, J ; Darabi, M.A ; Haghniaz, R ; Dokmeci, M.R ; Annabi, N ; Ahadian, S ; Khademhosseini, A ; Sharif University of Technology
IOP Publishing Ltd
2022
Abstract
Droplet-based microfluidic systems have been employed to manipulate discrete fluid volumes with immiscible phases. Creating the fluid droplets at microscale has led to a paradigm shift in mixing, sorting, encapsulation, sensing, and designing high throughput devices for biomedical applications. Droplet microfluidics has opened many opportunities in microparticle synthesis, molecular detection, diagnostics, drug delivery, and cell biology. In the present review, we first introduce standard methods for droplet generation (i.e. passive and active methods) and discuss the latest examples of emulsification and particle synthesis approaches enabled by microfluidic platforms. Then, the applications...
Observational comparative study in Kühni and ORC agitated columns for the mechanism and performance of molybdenum extraction under various hydrodynamic conditions
, Article International Journal of Heat and Mass Transfer ; Volume 185 , 2022 ; 00179310 (ISSN) ; Torkaman, R ; Torab-Mostaedi, M ; Asadollahzadeh, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The present work is expressed to interpret the hydrodynamic parameters of rotation extraction columns in the reactive and non-reactive systems. The solvent extraction technique has been utilized for optimizing the transportation of molybdenum ions to the organic phase in two agitated columns (ORC and Kühni columns). Dispersed phase volume fraction, average droplet diameter, slip velocity, size distribution, and ions permeability of the aqueous phase have been investigated in terms of changing the operational variables including the agitation rate, flow rate of the inlet dispersed and continuous phases, column geometry, and reaction conditions. By considering the reactive and non-reactive...
Microfluidics experimental investigation of the mechanisms of enhanced oil recovery by low salinity water flooding in fractured porous media
, Article Fuel ; Volume 314 , 2022 ; 00162361 (ISSN) ; Fatemi, M ; Masihi, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Spontaneous imbibition of water from fracture into the matrix is considered as one of the most important recovery mechanisms in the fractured porous media. However, water cannot spontaneously imbibe into the oil-wet rocks and as a result oil won't be produced, unless the capillary pressure barrier between fracture conduits and matrix is overcome. Wettability alteration is known as the main affecting mechanism for low salinity water flooding (LSWF), however, its effectiveness in fractured porous media has been less investigated, especially in the case of possible pore scale displacement mechanisms. In this study, the effectiveness of LSWF (diluted seawater) on oil recovery is compared to the...
Computational simulation of water removal from a flat plate, using surface acoustic waves
, Article Wave Motion ; Volume 111 , 2022 ; 01652125 (ISSN) ; Shams Taleghani, A ; Sheikholeslam, M ; Ahmadi, G ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Minimization of drop contact time is so important and critical for applications such as self-cleaning and anti-corrosion. In recent years, surface acoustic waves are presented as a powerful method for the manipulation of the drops. In this manuscript, a numerical study of drop shedding under the effect of acoustic waves is presented, which may have potential use in the anti-icing systems. Therefore, the effects of different parameters, such as acoustic wave frequency, amplitude, and direction of the wave on the water removal, are investigated. For this purpose, a color gradient lattice Boltzmann method (LBM) is developed and used in these simulations. The acoustic actuator effect is added as...
Fluid flow and heat transfer in microchannel with and without porous medium under constant heat flux
, Article Sadhana - Academy Proceedings in Engineering Sciences ; Volume 47, Issue 2 , 2022 ; 02562499 (ISSN) ; Sharif University of Technology
Springer
2022
Abstract
In this study, the heat transfer and fluid flow characteristics of a three-dimensional microchannel that is partially filled with a layer of porous medium at its bottom solid wall is investigated. The microchannel is consisted of a clear fluid flow region, solid walls and a porous layer that is attached to its solid bottom wall. A constant heat flux is applied to the bottom wall of the microchannel. Darcy-Brinkman-Forchheimer model is used to simulate the fluid flow inside the porous medium. The novelty of this work is to investigate thoroughly and precisely the effect of using of porous layer configuration in MCHSs on hydraulic and thermal performances. The effect of porous layer thickness,...
Investigating the effects of precursor concentration and gelling parameters on droplet-based generation of Ca-Alginate microgels: identifying new stable modes of droplet formation
, Article Materials Today Chemistry ; Volume 24 , 2022 ; 24685194 (ISSN) ; Rezaeian, M ; Mahmoudi, Z ; Shamloo, A ; Kazemzadeh Hannani, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Droplet-based microfluidics is an attractive approach for producing microgels due to its high potential to control the size and shape of the particles and precisely entrap the substances within the hydrogel matrix. However, the microfluidic generation of monodisperse microgels with desired structures is still challenging. Indeed, the rheological and interfacial properties of the immiscible fluids, as well as the adopted gelling strategy, play important roles in microfluidic methods. Herein, sodium alginate droplets with different concentrations are generated via a microfluidic device with a flow-focusing unit. Besides, a combined in situ and ex situ strategy is optimized to crosslink sodium...
Tuning the wetting properties of SiO2-based nanofluids to create durable surfaces with special wettability for self-cleaning, anti-fouling, and oil-water separation
, Article Industrial and Engineering Chemistry Research ; Volume 61, Issue 23 , 2022 , Pages 8005-8019 ; 08885885 (ISSN) ; Ghazanfari, M. H ; Molaei Dehkordi, A ; Sharif University of Technology
American Chemical Society
2022
Abstract
Surfaces with special wettability have aroused lots of attention due to their broad applications in many fields. In this work, we systematically report selective and various fabrications of nanofluids based on readily available materials such as SiO2 nanoparticles and polydimethylsiloxane to create superhydrophobic, superoleophobic, superhydrophilic/superoleophobic, and underwater superoleophobic coatings. The efficiency of prepared coatings is investigated on mineral rock plates as porous substrates via the straightforward and cost-effective solution-immersion technique. The static water contact angle of 170°, effortless bouncing of water droplets, and self-cleaning property with a near...
Thermal and hydraulic performance of rectangular microchannel heat sinks with trapezoidal porous configuration
, Article Numerical Heat Transfer; Part A: Applications ; Volume 81, Issue 3-6 , 2022 , Pages 72-93 ; 10407782 (ISSN) ; Vafai, K ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
In this article, the thermal and hydraulic capacity of a rectangular microchannel heat sink with different trapezoidal porous configuration’s inlet heights (Formula presented.) and outlet heights (Formula presented.) are examined. A three-dimensional model is used for microchannels with miscellaneous trapezoidal porous configuration’s inlet and outlet heights, and the laminar fluid flow and conjugate heat transfer equations are numerically solved. Darcy-Brinkmen-Forchheimer equation is utilized for transport through the porous region. For microchannels with miscellaneous porous distribution’s inlet and outlet heights, the Nusselt number, pressure drop and figure of merit (FOM), a criterion...
Heat transfer of power-law fluids under electrowetting actuation in structured microchannels
, Article International Communications in Heat and Mass Transfer ; Volume 130 , 2022 ; 07351933 (ISSN) ; Merdasi, A ; Moosavi, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The dynamics and heat transfer performance of droplets play an important role in electrowetting systems. Contrary to the growing trend towards non-Newtonian fluids in electrotechnical systems, most researchers have focused on Newtonian fluids. In the current study, the interface is tracked by the phase-field method and afterwards, the numerical model is confirmed by comparing the results obtained from previous experimental and theoretical works. Several parameters such as power-law index and contact angle are analyzed. Furthermore, the dynamics and heat transfer of the droplets on chemically or topographically structured substrates in the presence of electrowetting are examined. It has been...
Magnetic field-induced control of a compound ferrofluid droplet deformation and breakup in shear flow using a hybrid lattice Boltzmann-finite difference method
, Article International Journal of Multiphase Flow ; Volume 146 , 2022 ; 03019322 (ISSN) ; Bijarchi, M. A ; Ghorbanpour Arani, A ; Rahimian, M. H ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The deformation and breakup dynamics of a compound ferrofluid droplet under shear flow and uniform magnetic field are numerically studied in this paper. Utilizing magnetic field provides the possibility to obtain better control over the compound droplet morphology and breakup in a simple shear flow. To solve the governing equations for interfaces motion and hydrodynamics, the conservative phase field lattice Boltzmann model is employed, and a finite difference approach is applied for calculating the magnetic field. To verify the accuracy of present simulations, the results are validated with those of four relevant benchmarks including liquid lens between two stratified fluids, three-phase...
Exact hydrodynamic description of pilot plant Oldshue-Rushton contactor: a case study with the introduction of selenium and tellurium into reaction system
, Article International Journal of Environmental Analytical Chemistry ; Volume 102, Issue 16 , 2022 , Pages 4191-4207 ; 03067319 (ISSN) ; Torkaman, R ; Torab Mostaedi, M ; Asadollahzadeh, M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
In this paper, the hydrodynamic behaviour of the chemical reaction system (selenium, tellurium, and TBP) was interpreted in the Oldshue-Rushton extraction column. The optimum operating parameters for extracting the selenium and tellurium from chloride medium were carried out by using the batch experiments. The feed acidity of 5 molar and solvent phase with 20% (v/v) TBP in kerosene were optimised to examine the hydrodynamic parameters of the mentioned column. The impacts of operating variables such as rotor speed, inlet aqueous phase velocity, and inlet solvent phase velocity on the dispersed phase hold-up, mean drop size, slip velocity, drop size distribution, and extraction rate were...
Multi-objective optimization of acetone droplet impingement on phase change material in direct-contact discharge method
, Article Journal of Energy Storage ; Volume 46 , 2022 ; 2352152X (ISSN) ; Aria, H. P ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Improving the discharge process of phase change materials (PCMs) is of great importance and can be effective for thermal energy storage (TES) systems. In this research, the direct-contact method for acetone droplet on molten paraffin is optimized to enhance the efficiency of the discharge process of PCMs and TES systems working with intermediate boiling fluid (IBF). In order to improve the storage rate and increase the freezing rate in the system, the NSGA-II algorithm is used. When the acetone droplet hits, owing to its low boiling point relative to the temperature of molten paraffin, the acetone evaporates, causing the creation of solidified paraffin area. The main goal of the current...
Predicting the effects of environmental parameters on the spatio-temporal distribution of the droplets carrying coronavirus in public transport – A machine learning approach
, Article Chemical Engineering Journal ; Volume 430 , 2022 ; 13858947 (ISSN) ; Najm Abad, J. M ; Alizadeh, R ; Wongwises, S ; Doranehgard, M. H ; Jowkar, S ; Karimi, N ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Human-generated droplets constitute the main route for the transmission of coronavirus. However, the details of such transmission in enclosed environments are yet to be understood. This is because geometrical and environmental parameters can immensely complicate the problem and turn the conventional analyses inefficient. As a remedy, this work develops a predictive tool based on computational fluid dynamics and machine learning to examine the distribution of sneezing droplets in realistic configurations. The time-dependent effects of environmental parameters, including temperature, humidity and ventilation rate, upon the droplets with diameters between 1 and 250μm are investigated inside a...
Enhanced oil-in-water droplet generation in a T-junction microchannel using water-based nanofluids with shear-thinning behavior: A numerical study
, Article Physics of Fluids ; Volume 33, Issue 1 , 2021 ; 10706631 (ISSN) ; Shamloo, A ; Kazemzadeh Hannani, S ; Sharif University of Technology
American Institute of Physics Inc
2021
Abstract
Nanofluids are widely used as the continuous phase during droplet formation in microsystems due to their impressive features such as excellent thermal, magnetic, and interfacial properties. Although it is well-known that nanofluids are susceptible to exhibit non-Newtonian behavior even at a low concentration of nanoparticles, effects of non-Newtonian behavior of nanofluids have not been studied on droplet formation thus far. In this study, oil-in-water droplet formation with a relatively high viscosity ratio of the immiscible phases was studied numerically in a T-junction microchannel. To inspect the non-Newtonian effects of aqueous nanofluids on droplet formation, empirical data on the...
Simultaneous energy storage enhancement and pressure drop reduction in flat plate solar collectors using rotary pipes with nanofluid
, Article Energy and Buildings ; Volume 239 , 2021 ; 03787788 (ISSN) ; Rostamzadeh, H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Flat plate solar collectors waste a massive part of the heat accumulated near the contact region, mainly due to poor thermal characteristics of working fluid. The demanding power for pumping the flow through the pipes seems a permanent concern in solar collectors. Also, active methods seem not to be applicable in such systems due to the external energy requirement and cost associated with it. An innovative and simple technique is considered here to eliminate such deficiencies all at once by equipping the flat plate collector with rotary absorber pipes and Fe3O4/water nanofluid. Results indicate that the applied method improves the convection mechanism in each pipe by mixing the accumulated...