Search for: heat-transfer
Total 595 records
Investigation of heat transfer enhancement in a microchannel heat sink with the aid of internal fins: a metamodel approach, Article Computer Aided Chemical Engineering ; Volume 48 , 2020 , Pages 85-90 ; Kazemeini, M ; Sharif University of Technology
Elsevier B.V 2020
Heat transfer enhancement with microchannel tools has been increased in recent year. In this study effect of geometric parameters as well as Reynolds number have been studied with experimental design approach. A metamodel was generated in this study for pressure drop and average Nusselt number passed all statistical tests. Order of an individual effect upon a response has been evaluated and interaction effects have been determined. Numerical results indicated that heat transfer increased significantly with inserting pyramidal micro fins. © 2020 Elsevier B.V
Investigation of luminous/nonluminous radiation in a vortex engine, Article 2007 5th Joint ASME/JSME Fluids Engineering Summer Conference, FEDSM 2007, San Diego, CA, 30 July 2007 through 2 August 2007 ; Volume 1 SYMPOSIA, Issue PART B , August , 2007 , Pages 1979-1985 ; 0791842886 (ISBN); 9780791842881 (ISBN) ; Kargar, M ; Ghafourian, A ; Sharif University of Technology
Investigation of radiation heat transfer In vortex engine is an important and new phenomenon in combustion for scientists and combustion researchers. In this research some parts of the combustion chamber wall are insulated using Blanket as a high insulating material. The rate of radiative heat transfer to the chamber wall is calculated using temperature difference between inner and outer surface of chamber. In the experiments this parts are protected from direct contact with hot combustion media using quartz window. The luminous radiative transfer per volume of chamber and also volume of flame in a vortex engine are compared with that in a similar axial flow type engine. A detector sensitive...
Effect of vortex flow on heat transfer to combustion chamber wall, Article Journal of Engineering for Gas Turbines and Power ; Volume 129, Issue 2 , 2007 , Pages 622-624 ; 07424795 (ISSN) ; Saidi, M. H ; Jahangirian, S ; Abarham, M ; Sharif University of Technology
A new experimental facility was designed, fabricated, and tested to model and study the effect of bidirectional swirl flow on the rate of heat transfer to combustion chamber walls. Reduction of this heat transfer can result in time and cost of design and fabrication methods of combustion chambers. The experimental study was performed using propane and air with oxygen as fuel and oxidizer respectively. For similar flow rates, in cases where bidirectional flow was present, wall temperature reductions of up to 70% were observed. In cases where only some of the oxidizer was injected from the chamber end to generate the bidirectional swirl flow, the lowest wall temperature existed. This can be...
An analytical solution for thermally fully developed combined pressure - electroosmotically driven flow in microchannels, Article International Journal of Heat and Mass Transfer ; Volume 50, Issue 5-6 , 2007 , Pages 1087-1096 ; 00179310 (ISSN) ; Taghizadeh Manzari, M ; Hannani, S. K ; Sharif University of Technology
An analytical solution is presented to study the heat transfer characteristics of the combined pressure - electroosmotically driven flow in planar microchannels. The physical model includes the Joule heating effect to predict the convective heat transfer coefficient in two dimensional microchannels. The velocity field, which is a function of external electrical field, electroosmotic mobility, fluid viscosity and the pressure gradient, is obtained by solving the hydrodynamically fully-developed laminar Navier-Stokes equations considering the electrokinetic body force for low wall zeta potentials. Then, assuming a thermally fully-developed flow, the temperature distribution and the Nusselt...
Evaluation of imperial performance characteristic of turbocharger turbine and compressor, Article 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference Proceedings, San Francisco, CA, 5 June 2006 through 8 June 2006 ; Volume 2 , 2006 , Pages 1019-1028 ; 1563478153 (ISBN); 9781563478154 (ISBN) ; Hajilouy, A ; Shahhosseini, M. R ; Sharif University of Technology
Performance characteristics of turbocharger turbine and compressor such as efficiency, mass parameter and power are determined experimentally at turbocharger laboratory. Accurate determination of the performance map is significant for manufacturers as well as end users. To this end accurate measurement of test parameters such as temperature, pressure, and speed are required. In this paper an analytic method to predict the measurement uncertainties in turbocharger laboratory, is described. Furthermore the effect of each test parameter on the performance uncertainty is considered. Test parameters that have the most significant influence on the performance uncertainties are identified....
A review on the applications of micro-/nano-encapsulated phase change material slurry in heat transfer and thermal storage systems, Article Journal of Thermal Analysis and Calorimetry ; Volume 145, Issue 2 , 2021 , Pages 245-268 ; 13886150 (ISSN) ; Mahmoudian, A ; Mohammadi, O ; Shafii, M. B ; Jafari Mosleh, H ; Zandieh, M ; Ahmadi, M. H ; Sharif University of Technology
Springer Science and Business Media B.V 2021
In modern heat transfer systems, thermal storage not only causes the balance between demand and supply, but also improves the heat transfer efficiency in these systems. In the present study, a comprehensive review of the applications of micro- or nano-encapsulated phase change slurries (MPCMs/NPCMs), as well as their effects on thermal storage and heat transfer enhancement, has been conducted. MPCMs/NPCMs have a myriad of applications and various usages such as pipe and channel flows, photovoltaic/thermal, solar heaters, air conditioning systems, storage tanks and heat pipes that have been categorized and studied. It was found that there are many advantageous adding MPCM/NPCM to the base...
A new approach to heat and mass transfer in a rotary dehumidifier: Modeling and simulation, Article 2005 ASME Fluids Engineering Division Summer Meeting, FEDSM2005, Houston, TX, 19 June 2005 through 23 June 2005 ; Volume 2005 , 2005 , Pages 1268-1273 ; 0791837602 (ISBN); 9780791837603 (ISBN) ; Van Paassen, D ; Saidi, M. H ; ASME Fluids Engineering Division ; Sharif University of Technology
In this paper the analytical and simulation modelling of the combined heat and mass transfer processes that occur in a solid desiccant wheel is carried out. Using the numerical method, the performance of an adiabatic rotary dehumidifier is parametrically studied, and the optimal rotational speed is determined by examining the outlet adsorption-side humidity profiles. An approach to compare the solutions for different conditions used in air dehumidifier has been investigated according to the previous published studies. Comparing the simulated results with the published actual values of an experimental work substantiates the validity of model. The model accuracy with respect to the key...
Offshore accidents and effects on their performances, Article Ocean '04 - MTS/IEEE Techno-Ocean '04: Bridges across the Oceans - Conference Proceedings, Kobe, 9 November 2004 through 12 November 2004 ; Volume 1 , 2004 , Pages 212-217 ; 0780386698 (ISBN) ; Hemati, P ; Sharif University of Technology
Marine accidents are some of the risk sources on human life at sea and also make the founded budget to be sank to the deep. In order to prevent these damages and losses, it is necessary to do a proper understanding of these accidents. Offshore systems as of the main parts of ocean structures and their accidents are considered here in this paper. From 1975 some data showing offshore accidents are captured in the Worldwide Offshore Accident Databank (WOAD), which are the main data bank to be used in this study. These data are about offshore damages and collapses due to Fires, Blowout, Anchor failure, Capsize, Explosion, etc. The main scope of the study is on fixed offshores, named jackets...
Investigating the use of cooling surfaces in solid-state fermentation tray bioreactors: Modelling and experimentation, Article Journal of Chemical Technology and Biotechnology ; Volume 79, Issue 11 , 2004 , Pages 1228-1242 ; 02682575 (ISSN) ; Roostaazad, R ; Safekordi, A ; Bozorgmehri, R ; Mitchell, D. A ; Sharif University of Technology
The effect of wall cooling in tray-type solid-state fermenters was investigated by cultivation of Aspergillus niger ATCC 10 864 on wheat bran. Temperature, moisture, pH and glucoamylase activity in the bed were monitored. Application of the heat exchanger plate reduced the overall water loss but increased the heterogeneity of moisture distribution in the bed. Moisture content increased markedly close to the heat transfer plate while the upper regions of the bed dried out. The thermal conductivity of the bed was measured to be 0.19 Wm-1 K-1. At these conditions and depending on the air flow rate, 58-82% of the metabolic heat was removed via conduction towards the plate. A mathematical model...
Fluid flow and heat transfer around circular cylinders in the presence and no-presence of porous media, Article Journal of Porous Media ; Volume 7, Issue 3 , 2004 , Pages 239-247 ; 1091028X (ISSN) ; Nouri Borujerdi, A ; Sharif University of Technology
Steady-state laminar and incompressible fluid flow and forced-convection heat transfer from a circular cylinder and an array of circular cylinders in the presence and no-presence of porous media are investigated. Various mathematical and numerical models are compared and the effects of porous media on heat transfer enhancement are studied. Navier-Stokes equations are used for the analysis of laminar fluid flow and heat transfer. However, the Darcy and extended Darcy-Brinkman models are used for the analysis of fluid flow and heat transfer in porous media. The cylinders are at constant temperature and the analysis is restricted to the low- and intermediate-Peclet-number regimes (Pr = 1, Re ≤...
Modeling the shape control of beam structures by shape memory alloy actuators, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 323-330 ; 0791841731 (ISBN); 9780791841730 (ISBN) ; Sharif University of Technology
American Society of Mechanical Engineers 2004
In this paper, the application of an actuator wire made of shape memory alloy (SMA) and externally attached to a cantilever beam is analyzed. To this end, an integrated model that includes the constitutive equations of the SMA, the phase transformation equations from martensite to austenite and vice versa, the heat transfer equation for the SMA that also includes the input energy from an electric source, and the equations of the elastic deformation of the cantilever beam as well as the SMA wire, is presented. The simultaneous solution of the mentioned set of equations can result in the evaluation of the system response to an electrical activation of SMA
Role of liquid compressional viscosity in the dynamics of a sonoluminescing bubble, Article Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics ; Volume 70, Issue 1 , 2004 , Pages 6- ; 1063651X (ISSN) ; Sadighi Bonabi, R ; Sharif University of Technology
The well-known Rayleigh-Plesset [Formula presented] equation is the basis of almost all hydrodynamical descriptions of single-bubble sonoluminescence [Formula presented]. A major deficiency of the [Formula presented] equation is that it accounts for viscosity of an incompressible liquid and compressibility, separately. By removing this approximation, a new modification of the [Formula presented] equation is presented considering effect of compressional viscosity of the liquid. This modification leads to addition of a new viscous term to the traditional bubble boundary equation. Influence of this new term in the dynamics of a sonoluminescing bubble has numerically been studied considering...
Measurement of heat characteristics of a new incubator with a chemical energy source, Article International Journal of Engineering, Transactions A: Basics ; Volume 17, Issue 4 , 2004 , Pages 319-328 ; 17281431 (ISSN) ; Farhanieh, B ; Khodadadeh, Y ; Sharif University of Technology
National Research Center of Medical Sciences 2004
A heat transfer model was developed for a new non-electric infant's transport incubator. The source of heat comprises a super saturated solution of Sodium Acetate and a metal disk (activator) in a plastic container. Estimating the number of the chemical bags required for different ambient temperature was the goal. First the quantity of heat generated by the chemical was appointed through experiments and use of a parameter estimation method. The number of the chemical bags were also estimated through a numerical-experimental method
Thermal stress analysis of concrete arch dams due to enviromental action, Article 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; Volume 375, Issue 1 , 2004 , Pages 393-402 ; 02725673 (ISSN) ; Ghaemian, M ; Sharif University of Technology
American Society of Mechanical Engineers (ASME) 2004
A three-dimensional finite element analysis was carried out to determine the annual variation of temperature and thermal stresses of a concrete arch dam. Appropriate heat transfer boundary conditions in the dam body were used for air and reservoir temperature as well as solar radiation variations. Karaj arch dam in Iran was used as a case study. The rate of convergence of the numerical solution is examined. Results of the finite element analysis show that probable cracks occur in a very narrow region of the downstream face. Thermal loads have the most significant effects for causing downstream cracks in comparison with self-weigh and hydrostatic loads. The cracked areas of downstream face...
A quantative approach to estimate the life expectancy of motor insulation systems, Article IEEE Transactions on Dielectrics and Electrical Insulation ; Volume 7, Issue 6 , 2000 , Pages 790-796 ; 10709878 (ISSN) ; Sharif University of Technology
Electric motors represent the largest single load in most power systems. With continuing increase in nonlinear loads, the effects of harmonic contents of power systems on various components is becoming more important. This paper is concerned with the effect of power system harmonics and voltage unbalance on the useful life of electric motors. A simple equivalent circuit is used to calculate the additional heat losses caused by supply distortions. A lumped-parameter thermal network is proposed to calculate the resulting heat distribution within the machine. An Arrhenius chart is then used to estimate motor insulation remaining life. The proposed approach is used to determine the effect of...
Heat transfer enhancement of Fe3O4 ferrofluids in the presence of magnetic field, Article Journal of Magnetism and Magnetic Materials ; Volume 429 , 2017 , Pages 314-323 ; 03048853 (ISSN) ; Shahrokhi, M ; Molaei Dehkordi, A ; Abbasi, Z ; Sharif University of Technology
Elsevier B.V 2017
In this article, three-dimensional (3D) forced-convection heat transfer of magnetic nanofluids in a pipe subject to constant wall heat flux in the presence of single or double permanent magnet(s) or current-carrying wire has been investigated and compared. In this regard, laminar fluid flow and equilibrium magnetization for the ferrofluid were considered. In addition, variations of magnetic field in different media were taken into account and the assumption of having a linear relationship of magnetization with applied magnetic field intensity was also relaxed. Effects of magnetic field intensity, nanoparticle volume fraction, Reynolds number value, and the type of magnetic field source...
Experimental Study of Internal Forced Convection of Ferrofluid Flow in Magnetizable Porous Media, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad
The use of nanofluids to improve the heat transfer has a special attention in the industry. researches focus on the efficiency of heat transfer nanofluids dates back to 1998. Ferrofluids are a particular type of nanofluids which their nanoparticles have magnetic effect and heat transfer can be increased by applying magnetic field to them. In this work, thermal and hydrodynamic performance of ferromagnetic fluid which flows through a copper tube in thermal entrance region has been studied. The flow in the tube is laminar and is affected by constant heat flux. Part of the tube contains a porous medium with paramagnetic properties and porosity of 0.46. Ferrofluid is composed of F e3O4 and water...
Three-dimensional Aerothermal Shape Optimization of Turbine Blade, Using Gradient Adjoint-based Methods, Ph.D. Dissertation Sharif University of Technology ; Mazaheri, Karim
The most important challenge and the most time consuming part of the gradient based optimization algorithms in the aerodynamic shape optimization problems is the evaluation of the sensitivity of the objective function with respect to the design variables. The adjoint method which has been the subject of many research in the recent three decades, is capable of computing the complete gradient information needed for optimization by solving the governing flow equations and their corresponding adjoint equations only once, regardless of the number of design parameters. In this study, the continues adjoint equations for compressible inviscid and viscous flows are derived and the formulation of...
Experimental Investigation of Temperature Reduction of Photovoltaic Panels Using Porous Media, M.Sc. Thesis Sharif University of Technology ; Nouri Borojerdi, Ali
The limitation of fossil fuel sources and environmental damage caused by use of these fuels have made researches on applications of renewable energy, especially solar energy, to be an important issue in recent years. An important issue that arises in the use of photovoltaic panels is the reduction of their efficiency with increasing their temperature. By increase of a degree of Celsius, the efficiency of the photovoltaic panel decreases by 0.45%. The aim of this project is to reduce the temperature of the photovoltaic panel by using porous medium and air. The porous medium used as fins under the panel.Experimental results have shown that by using the medium placed under the photovoltaic...
Thermal performance of an open loop pulsating heat pipe with ferrofluid (Magnetic Nano-Fluid), Article ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012 ; 2012 , Pages 185-190 ; 9780791854778 (ISBN) ; Mohammadi, M ; Saidi, M. H ; Afshin, H ; Shafii, M. B ; Kazemzadeh Hannani, S ; Sharif University of Technology
In the present research an experimental investigation is performed to explore the effects of working fluid, heat input, ferrofluid concentration, magnets location, and inclination angle on the thermal performance of an Open Loop Pulsating Heat Pipe (OLPHP). Obtained results show that using ferrofluid can improve the thermal performance and applying a magnetic field on the water based ferrofluid decreases the thermal resistance. It shows that at an inclination angle of the OLPHP to be zero, the thermal performance of the present OLPHP reduces. Best heat transfer capability was achieved at 67.5 degree relative to horizontal axis for all of working fluids. Variation of the magnets location...