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    Experimental flow visulization of single swirl spray pattern at various pressure drops

    , Article 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2003, Huntsville, AL, 20 July 2003 through 23 July 2003 ; 2003 ; 9781624100987 (ISBN) Ghorbanian, K ; Ashjaee, M ; Soltani, M. R ; Mesbahi, M. H ; Morad, M. R ; Sharif University of Technology
    An experimental investigation of the flow field of pressure swirl atomizers for different pressure drops is performed. Two experimental methods are employed. For low injection pressures, a visual study is conducted while for higher pressures the velocity components and size of the droplets are measured by using Phase Doppler Anemometer. The spray formation, spray cone angle, and breakup length are visually investigated. Velocity and size of the droplets are measured on a plane of measurement along the axis of the spray so that the properties are carried out in a radial direction as a function of both pressure drop and axial distance from the nozzle. Self-similar mean axial velocity profiles... 

    Neural network analysis of single swirl spray pattern at various pressure drops

    , Article 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2003, Huntsville, AL, 20 July 2003 through 23 July 2003 ; 2003 ; 9781624100987 (ISBN) Soltani, M. R ; Ghorbanian, K ; Ashjaee, M ; Morad, M. R ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2003
    Radial Basis Function, a neural network based interpolation method, is used to simulate swirling spray phenomenon. From this model, the profile of mean velocity components' distribution along the main axis of the injector at various pressure drops and spray measurements' plane are obtained and analyzed. Experimental data obtained through Phase Doppler Anemometer is used to train this model. The results are compared with experimental data as well as to those obtained through General Regression Neural Network method as another neural network based interpolation method investigated previously by the authors. © 2003 by M.R. Soltani  

    Hydraulic Evaluation and Pressure Estimation in Two-Phase Air-Water Slug Flow Using Soft Computing

    , M.Sc. Thesis Sharif University of Technology Akbarian, Hadi (Author) ; Borghei, Shamsai (Supervisor) ; Shamsaee, Abolfazl (Co-Advisor)
    Study of hydraulic characteristics of two-phase flow is one of the important issues in hydraulic engineering. Two-phase flows usually accur in hydraulic structures such as pressurized flow tunnels, culverts, sewer pipes, junctions, and similar conduits. Under certain conditions, air may also be introduced into pressurized intake systems, which may form large bubbles in portions of the pipe. The bubbles may, in turn, cause an unstable slug flow, or other flow patterns. Slug flow is one of the most probable patterns in these flows. Prediction of pressure in this situation is a complex subject which despite its great importance is rarely discussed. In this study, the results of a laboratory... 

    Eperimental Investigation of Pressure Drop by Using the Superhydrophobic Surfaces

    , M.Sc. Thesis Sharif University of Technology Rad, Vahid (Author) ; Mousavi, Ali (Supervisor) ; Nouri Boroojerdi, Ali (Supervisor)
    Through history, increased energy consumption has been encouraged researchers to improve the performance of energy-using devices. Some researchers believe that hydrophobic surfaces can play an important role in this regard.The encounter and the presence of water on different surfaces can have different effects on them. The surface sedimentation of these surfaces, the eating of metal surfaces, the drag force (water friction) due to water collision with the moving object in water and the attachment of algae And other marine organisms to the surfaces, including the limitations and problems faced by professionals and staff associated with this sector.In the present study, the drag reduction of... 

    Experimental Study on Two-Phase Flow Characteristics in Micro-Channels

    , M.Sc. Thesis Sharif University of Technology Yavari, Hadi (Author) ; Nouri, Ali (Supervisor)
    The present study provids an experimental investigation on two-pase flow characteristics in microchannels. Experiment were conducted with a mixture of air and water in horizontal circular pyrex channel with 400µm inner diameter. The pressure drop and flow rates of the liquid and gas were measured using new method and images of the flow patterns recorded by high shutter speed camera. The gas and liquid superficial velocity ranges were 0.025-12.5m/s and 0.016-3.6m/s, respectively. The flow pattern map is developed from the observed flow patterns based on phases superficial velocity as wel as We numbers of liquid and gas phases. The flow pattern map is compared with those of larger channels.... 

    Experimental and simulation investigation of pulsed heat pipes in gas compressors

    , Article AIMS Energy ; Volume 8, Issue 3 , 2020 , Pages 438-454 Alizadeh, A ; Shafii, M. B ; Mirzahosseini, A. H ; Ataei, A ; Sharif University of Technology
    AIMS Press  2020
    In natural gas pressure boosting stations, air coolers are used to reduce the gas temperature. Pressure drop as an essential factor in determining the energy performance of any pressure boosting station has a significant impact on the overall performance of the gas transmission. In this paper, a laboratory pilot is designed to investigate the effect of pressure drop reduction on the use of heating pipes at the air coolers. In addition, as a case for a gas pressure boosting station, its impact over energy performance index and pressure drop parameter has been calculated through simulating. The results show, implemented PHP tubes in an air cooler, lead to reduce tube length and improve... 

    Fate of intermediate biodegradation products of triethyl amine in a compost-based biofiltration system

    , Article International Journal of Environmental Research ; Volume 1, Issue 2 , 2007 , Pages 163-169 ; 17356865 (ISSN) Torkian, A ; Keshavarzi Shirazi, H ; Mehrdadi, N ; Sharif University of Technology
    Biofiltration of Triethylamine (TEA) vapor used as a catalyst in casting operations was evaluated in this study The unit consisted of a 6-L three-stage biofilter containing a mixture of compost and wood chips (40:60 v/v) as the filter medium. Seed microbial population from municipal activated sludge was acclimated for a period of three weeks prior to the actual experimental runs. In the startup period, high pH values up to 10 was observed due to alkaline nature of TEA and inadequate formation of biofilm and low overall biodegradation. Steady increase of organic-N concentration along with gradual upward trend of pressure drop indicated sound establishment of microbial population. Operational... 

    A simultaneous methodology for the optimal design of integrated water and energy networks considering pressure drops in process industries

    , Article Process Safety and Environmental Protection ; Volume 103, Issue Part B , 2016 , Pages 442-454 ; 09575820 (ISSN) Torkfar, F ; Avami, A ; Sharif University of Technology
    Institution of Chemical Engineers 
    This paper presents a simultaneous methodology for the optimal design of integrated water and energy networks. Heat transfer coefficients are not constant but are related to the velocity of the streams. Pressure drops in heat exchangers and related power costs are considered. The model is a non-convex MINLP (mixed-integer non-linear program) model, in which the objective is to minimize the total annual costs. To accomplish this task, a new superstructure is proposed that follows the energy and mass streams from sources to sinks, enabling us to consider heat exchange between streams in two separate stages of the HENS before and after mixers. Furthermore, heat recovery from wastewater is... 

    An investigation on the effects of gas pressure drop in heat exchangers on dynamics of a free piston stirling engine

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 30, Issue 2 , 2017 , Pages 1243-1252 ; 1728144X (ISSN) Zare, S ; Tavakolpour Saleh, A. R ; Aghajanzadeh, O ; Sharif University of Technology
    Materials and Energy Research Center  2017
    This paper is devoted to study the effects of pressure drop in heat exchangers on the dynamics of a free piston Stirling engine. First, the dynamic equations governing the pistons as well as the gas pressure equations for hot and cold spaces of the engine are extracted. Then, by substituting the obtained pressure equations into the dynamic relationships the final nonlinear dynamic equations governing the free piston Stirling engine are acquired. Next, effects of the gas pressure drop in heat exchangers on maximum strokes of the pistons and their velocities and accelerations are investigated. Furthermore, influences of pressure drop increase in the heat exchangers on maximum and minimum gas... 

    Study of fast transient pressure drop in vver-1000 nuclear reactor using acoustic phenomenon

    , Article Science and Technology of Nuclear Installations ; Volume 2018 , 2018 ; 16876075 (ISSN) Heidari Sangestani, S ; Rahgoshay, M ; Vosoughi, N ; Athari Allaf, M ; Sharif University of Technology
    Hindawi Limited  2018
    This article aims to simulate the sudden and fast pressure drop of VVER-1000 reactor core coolant, regarding acoustic phenomenon. It is used to acquire a more accurate method in order to simulate the various accidents of reactor core. Neutronic equations should be solved concurrently by means of DRAGON 4 and DONJON 4 coupling codes. The results of the developed package are compared with WIMS/CITATION and final safety analysis report of Bushehr VVER-1000 reactor (FSAR). Afterwards, time dependent thermal-hydraulic equations are answered by employing Single Heated Channel by Sectionalized Compressible Fluid method. Then, the obtained results were validated by the same transient simulation in a... 

    Numerical investigation of rectangular-cut twisted tape insert on performance improvement of heat exchangers

    , Article International Journal of Thermal Sciences ; Volume 138 , 2019 , Pages 75-83 ; 12900729 (ISSN) Nakhchi, M. E ; Esfahani, J. A ; Sharif University of Technology
    Elsevier Masson SAS  2019
    A numerical analysis has been performed to investigate the flow structure and thermal hydraulic performance of turbulent flow through circular tube equipped with twisted tapes with different cut shapes. The geometries of cuts are rectangular with different cut ratios 0.25

    Comparative analysis of different static mixers performance by CFD technique: An innovative mixer

    , Article Chinese Journal of Chemical Engineering ; Volume 28, Issue 3 , 2020 , Pages 672-684 Haddadi, M. M ; Hosseini, S. H ; Rashtchian, D ; Olazar, M ; Sharif University of Technology
    Chemical Industry Press  2020
    The flow and mixing behavior of two miscible liquids has been studied in an innovative static mixer by using CFD, with Reynolds numbers ranging from 20 to 160. The performance of the new mixer is compared with those of Kenics, SMX, and Komax static mixers. The pressure drop ratio (Z-factor), coefficient of variation (CoV), and extensional efficiency (α) features have been used to evaluate power consumption, distributive mixing, and dispersive mixing performances, respectively, in all mixers. The model is firstly validated based on experimental data measured for the pressure drop ratio and the coefficient of variation. CFD results are consistent with measured data and those obtained by... 

    Effect of the geometry of a swirl generator on energy loss and shockwave position in arina nozzle

    , Article Chemical Engineering and Technology ; Volume 43, Issue 8 , August , 2020 , Pages 1596-1607 Majidi, D ; Farhadi, F ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    To investigate the effect of the swirl generator (SG) on shockwave position and pressure drop, 3D simulation is conducted and validated by Arina's study. An increase of the blade number, height, and end angle leads to shockwave displacement toward the nozzle outlet. The maximum increment of the shockwave displacement, which is due to enlarging the angle of the blade end, is about 47 %. For this case, the pressure drop share of the SG is nearly half of the total pressure drop, while the residence time of particles is prolonged by about 51 %. As a general finding, increasing the swirl intensity provides a longer residence time to separate adequately the liquid from the gas. However, a higher... 

    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) Bezaatpour, M ; Rostamzadeh, H ; Sharif University of Technology
    Elsevier Ltd  2021
    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... 

    Liquid flow analysis in concentric annular heat pipes wicks

    , Article Journal of Porous Media ; Volume 8, Issue 5 , 2005 , Pages 471-480 ; 1091028X (ISSN) Nouri Borujerdi, A ; Layeghi, M ; Sharif University of Technology
    In this paper, two models are developed to predict liquid pressure drop and velocity profile in the wicks of concentric annular heat pipes. A steady-state incompressible laminar flow is modeled in the wicks based on velocity and pressure mean values by the extended Darcy-Brinkman model. The corresponding one- and two-dimensional governing equations are solved analytically and numerically, respectively, in the range of low to moderate radial Reynolds numbers. It has been found that there is a difference, about 12% in the worse case, between the total pressure drops of the two models. Whereas, the predicted total pressure drop by the one-dimensional model and that of the Darcy model are in... 

    Novel boundary condition implementation to model electroosmotic phenomenon in microchannels

    , Article Proceedings of the 7th International Conference on Nanochannels, Microchannels, and Minichannels 2009, ICNMM2009, 22 June 2009 through 24 June 2009, Pohang ; Issue PART A , 2009 , Pages 243-251 ; 9780791843499 (ISBN) Darbandi, M ; Farzinpour, P ; Sharif University of Technology
    This Paper presents simulation of Electroosmotic phenomenon in a capillary using an extended hybrid finite-volume-element method. Most of the last electroosmotic phenomenon studies in microchannels do not take into consideration the effect of reservoirs and pressure drops occurred at the inlet and outlet of the microchannel. This neglect may lead to a few drawbacks. For example, the incorrect pressure drops can significantly alter the flow patterns and mass flow rates in microchannels. As a remedy the use of reservoirs at the two ends of a microchannel has been recently practiced as a novel strategy to overcome this drawback. However, this remedy needs careful attention because the resulting... 

    Physical and hydraulic properties of a new spring packing

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Mafi, M ; Yazdani, F ; Farhadi, F ; Deldari, H ; Sharif University of Technology
    Physical and hydraulic properties of new stainless steel spring packing are introduced. The measured hydraulic properties are: dry and wetted packed bed pressure drop, loading and flooding points and the liquid holdups. The appropriate coefficients for predicting the mentioned hydraulic properties from different correlations are also reported. Hydraulic properties for this packing are compared with available packings. In spite of small size, the dry and wetted packed bed pressure drops of spring packing are less than similar Raschig and Protruded rings. The total liquid holdup of this packing is greater than other commercial packings. The big total liquid holdup and physical surface area are... 

    Simulation and exergy-method analysis of an industrial refrigeration cycle used in NGL recovery units

    , Article International Journal of Energy Research ; Volume 30, Issue 15 , 2006 , Pages 1336-1351 ; 0363907X (ISSN) Mehrpooya, M ; Jarrahian, A ; Pishvaie, M. R ; Sharif University of Technology
    The behaviour of an industrial refrigeration cycle with refrigerant propane has been investigated by the exergy method. An natural gas liquid recovery unit with its refrigeration cycle has been simulated to prepare the exergy analysis. Using a typical actual work input value; the exergetic efficiency of the refrigeration cycle is determined to be 26.51 % indicating a great potential for improvements. The obtained simulation results reveal that the exergetic efficiencies of the air cooler(s) and chilling sections get the lowest rank among the other compartments of refrigeration cycle. Refrigeration calculations have been carried out through the analysis of T-S and P-H diagrams where... 

    Optimization of the pem fuel cell cooling system by entropy generation minimization

    , Article 3rd International Conference on Fuel Cell Science, Engineering, and Technology, 2005, Ypsilanti, MI, 23 May 2005 through 25 May 2005 ; 2005 , Pages 441-448 ; 0791837645 (ISBN); 9780791837641 (ISBN) Sharifian, L ; Saidi, M. H ; Sharif University of Technology
    American Society of Mechanical Engineers  2005
    Cooling system is essential for high power fuel cells to maintain cells temperature in an acceptable limit. In this paper a suitable cooling system for the PEM fuel cell has been designed and optimized. The design includes the number of the cooling plates, the proper circuit of the cooling channels in the plates, the channel dimensions, the flow rate of the cooling fluid and its temperature. The optimization technique is minimization of the entropy generation through the cooling plates. The design of the cooling channels and plates is such that the plate temperature doesn't exceed from a desired temperature and the temperature variation in the plate becomes minimized. In this design, the... 

    Pressure drop reduction of power-law fluids in hydrophobic microgrooved channels

    , Article Physics of Fluids ; Volume 31, Issue 7 , 2019 ; 10706631 (ISSN) Javaherchian, J ; Moosavi, A ; Sharif University of Technology
    American Institute of Physics Inc  2019
    Using hydrophobic surfaces is one of the efficient methods to preserve energy in fluid transfer systems. However, the studies have been concentrated on Newtonian fluids despite the wide applications of non-Newtonian fluids in daily life and many industries such as the biological, foodstuff, chemical, petroleum, cosmetic, and lab on a chip fields. In this study, we consider power-law fluids as a typical example of non-Newtonian fluids and investigate the effect of hydrophobic microgrooves on the pressure drop in channels by utilizing the phase field method. We demonstrate that the optimum size of the rectangular microgrooves in which the maximum pressure drop reduction (PDR) happens for both...