دانلود مقاله High-Re Solutions for Incompressible Flow Using the Navier-Stokes Equations and a Multigrid Method, by U. GHIA, K. N. GHIA, AND C. T. SHIN, 1982
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دانلود مقاله Darcy Model for the Study of the Fluid Flow and Heat Transfer Around a Cylinder Embedded in Porous Media
Steady-state convective heat transfer around a circular cylinder
embedded in porous media is studied in the range of low and
moderate Peclet numbers less than 40. The cylinder is at constant
temperature and the Darcy model is used for the analysis of fluid
flow and heat transfer in porous media. The governing equations
are discretised using finite volume approach based on staggered
grids. The powerlaw scheme is used in the numerical solution and
a SIMPLE-like algorithm is developed and used in the solution process.
It is found that the numerical algorithm is sufficiently efficient
in the range of Peclet numbers less than 40. Parametric studies are
done for better understanding of the porous media effects on the
Nusselt number distribution, pressure distribution, and flow and
temperature fields around a circular cylinder. The results are compared
with the available numerical data in the literature and have
shown good agreements.
دانلود مقاله تحلیل عددی انتقال حرارت جابجایی از یک هیت سینک پره پینیدار با پین های دارای مقطع بیضوی با یا بدون فوم فلزی بینابینی Numerical Analysis of Convective Heat Transfer From an Elliptic Pin Fin Heat Sink With and Without Metal Foam Insert
A numerical analysis of forced convective heat transfer from an elliptical pin fin heat sink
with and without metal foam inserts is conducted using three-dimensional conjugate heat
transfer model. The pin fin heat sink model consists of six elliptical pin rows with 3 mm
major diameter, 2 mm minor diameter, and 20 mm height. The Darcy–Brinkman–
Forchheimer and classical Navier–Stokes equations, together with corresponding energy
equations are used in the numerical analysis of flow field and heat transfer in the heat
sink with and without metal foam inserts, respectively. A finite volume code with point
implicit Gauss–Seidel solver in conjunction with algebraic multigrid method is used to
solve the governing equations. The code is validated by comparing the numerical results
with available experimental results for a pin fin heat sink without porous metal foam
insert. Different metallic foams with various porosities and permeabilities are used in the
numerical analysis. The effects of air flow Reynolds number and metal foam porosity and
permeability on the overall Nusselt number, pressure drop, and the efficiency of heat sink
are investigated. The results indicate that structural properties of metal foam insert can
significantly influence on both flow and heat transfer in a pin fin heat sink. The Nusselt
number is shown to increase more than 400% in some cases with a decrease in porosity
and an increase in Reynolds number. However, the pressure drop increases with decreasing
permeability and increasing Reynolds number.
دانلود مقاله مروری برمطالعات عددی هیدرودینامیک جریان توده ای (slug flow) و انتقال حرارت در میکرو لوله ها و میکروکانالها A review on numerical studies of slug flow hydrodynamics and heat transfer in microtubes and microchannels
Numerical studies on the hydrodynamic and heat transfer characteristics of two-phase flows in small
tubes and channels are reviewed. These flows are non-boiling gas–liquid and liquid–liquid slug flows.
The review begins with some general notes and important details of numerical simulation setups. The
review is then categorized into two groups of studies: circular and non-circular channels. Different
aspects such as slug formation, slug shape, flow pattern, pressure drop and heat transfer are of interest.
The primary purpose of the present review is to report the existing numerical studies in order to highlight
the research gaps and suggestions for the future numerical simulations. Judging and/or comparing the
different works and correlations can be conducted separately for each of the sections reported here.
According to this review, there are some large gaps in the research literature, including pressure drop
and heat transfer in liquid–liquid slug flows. Gaps in research are also found in applications of non-circular
ducts, pressure drop and heat transfer in meandering microtubes and microchannels for both gas–
liquid and liquid–liquid two-phase flows.
دانلود مقاله مروری بر اثرات میدانهای مغناطیسی و میدانهای الکتریکی بر انتقال حرارت جوششی و شارحرارتی بحرانی(CHF) A Review on Effects of Magnetic Fields and Electric Fields on Boiling Heat Transfer and CHF
Taking advantage of electric fields and magnetic fields during boiling processes can be a very
beneficial way for enhancement of boiling heat transfer and increase of the critical heat flux
values. Applying magnetic fields and electric fields are promising active techniques which
contribute to higher heat flux accompanied by small wall superheat temperature. This paper
consist a complete review of published literature about effects of applying magnetic fields and
electric fields on heat transfer and critical heat flux during pool boiling and flow boiling
processes. The paper also includes the major affecting parameters and mechanisms reported in
the literature about the boiling heat transfer and critical heat flux in the presence of magnetic
fields and electric fields. The related achievements, results, inconsistencies and contradictions
existing in the literature are identified and discussed in detail. Some recommendations and
research directions for future studies are suggested.
دانلود مقاله مروری بر انتقال حرارت جوششی و رفتار لوله های گرمایی با سیالات دوباره مرطوب شونده (SRF)A review of boiling heat transfer and heat pipes behaviour with self-rewetting fluids
The self-rewetting fluid is the liquid which have an anomalous surface tension increasing with temperature
when the temperature exceeds a certain value. This particular property can cause the subcooled
liquid to be drawn towards the heated surface if a dry patch appears, thus making it possible for the
self-rewetting fluids to become promising working fluids. This paper presents an overview of the recent
developments of the research on boiling heat transfer using self-rewetting fluids. Thermophysical properties,
pool and flow boiling experiments and heat pipe applications of self-rewetting fluids have been
reported in this paper. It can be found that the use of self-rewetting fluids in a wide range of applications
appears promising. However, further detailed and valuable theoretical and numerical investigations are
necessary for us to better understand the boiling phenomenon of self-rewetting fluids.
دانلود مقاله مروری بر افزایش انتقال حرارت در جوشش با استفاده از مواد افزودنی/شناورسازها (سورفکتانتها)A review on augmentation of heat transfer in boiling using surfactants/additives
Studies of heat transfer enhancement in boiling
under various conditions and configurations have given different
results. Understanding the boiling behaviour from
these studies, literature is reviewed in terms of surface texture,
heater geometry and orientation, experimental and numerical
studies in presence of surfactant/additives. After understanding
different behaviour in boiling, the effect of environment
friendly surfactant is studied through literature review. Benchmarking
of experimental procedure is done by experimenting
and comparing some surfactants studied in literature.
دانلود مقاله مروری بر جوشش لایه ای در دماهای خیلی پایین A review of film boiling at cryogenic temperatures
Among the various modes of heat transport to liquids, film boiling is considered
to be an inefficient mechanism. However, in many practical engineering applications
it occurs. Consequently, film boiling must be studied and understood for design
applications. Film boiling is invariably encountered in quenching of metals, in
chilling of biological species, in regenerative cooling of rockets, and in cooling down
a cryogenic fuel tank, and occasionally film boiling can also happen in a nuclear
reactor or in a cryomagnet.
This paper will discuss what we know about film boiling and what future work
would be productive or of interest. The author will not attempt to cite every article
on film boiling that appears in the literature. Instead, the introductory portion of this
paper, which reviews what is known about film boiling, is designed to set the stage for
discussing those areas of film boiling where more study is needed.
The discussion will be divided into three parts: (1) film boiling of the unconstrained
liquid mass (Leidenfrost phenomenon); (2) pool film boiling; and (3) forcedconvective
film boiling inside a channel or tube.
دانلود مقاله مروری بر مدلسازی محاسباتی جوشش جریانی در میکروکانالها A Review of Computational Modelling of Flow Boiling in Microchannels
Flow boiling in microchannels has received enormous interest in academic research
over the past few decades because of its importance in the thermal management of
micro-structured devices. A vast number of experimental and theoretical studies have
been reported and an increasing number of computational studies of microchannel flow
boiling have been performed in the past few years. This article provides a review of the
previous studies of flow boiling in microchannels, with a focus on the computational
work. We present the governing equations, boundary conditions, numerical methods
and the mathematical treatment of phase change used. Some important numerical
studies are reviewed in detail and their strengths and weaknesses are presented. Finally,
a summary of the current status of modelling in this area is provided.
دانلود مقاله مروری بر مطالعه پارامتری انتقال حرارت در جوشش استخری نانوسیالها برای افزایش شار حرارتی بحرانی Parametric study of pool boiling heat transfer with nanofluids for the enhancement of critical heat flux: A review
Over the last decade, numerous investigations have been carried out using engineered colloidal fluids
called nanofluids in pool boiling for the enhancement of critical heat flux (CHF) which is otherwise
limited by the use of base fluids. Though there are contradicting results in CHF enhancement, almost all
the researchers identified that there is an enhancement in CHF by the addition of nanoparticles (1
e100 nm size) with base fluid. The deposition of nanoparticles on the heater surface during boiling of
nanofluids is the major factor for the enhancement of CHF. In fact, the CHF enhancement results are
influenced by the various parameters such as size of nanoparticles, method of preparation of nanofluids,
and its concentration. This article reviews in detail the various factors for the enhancement of CHF and
provides further research direction which helps the readers to understand the pool boiling heat transfer
in a better way. Also, the mechanisms of CHF enhancement by exploring various boiling heat transfer
theories have been addressed.
دانلود مقاله مروری بر افزایش انتقال حرارت جوششی نانوسیالها و پوششهای نانو A review of enhancement of boiling heat transfer through nanofluids and nanoparticle coatings
This review traces the development of nanofluid pool boiling from its beginning (1984) to the
present through a sampling of studies that have interested the authors and which have led to the
latest findings at the University of Texas at Arlington (UTA). The studies of thermophysical
properties of nanofluids are briefly covered. Several works in the last 7 years are highlighted to
illustrate the modes of nanofluid pool boiling testing, the variability of nanofluid boiling heat
transfer (BHT), and the postulations of causes of this behavior. Starting in 2006, the wettability
increase in the nanoparticle coating, generated during the nanofluid pool boiling, is recognized as
the source of critical heat flux (CHF) enhancement through its effect on the dynamics of hot spots
and departing bubbles. The reasons for the observed contradictory BHT behavior are not yet fully
clear, but recently at UTA, nanofluid boiling heat transfer has shown to be transient due to the
dynamic nature of the formation of the nanoparticle coating. Also at UTA, the mechanism of
nanoparticle deposition on the heated surface has been further confirmed. Thus, nanofluid boiling
has led back to heat transfer enhancement through surface modification in nanoscale. These
developments from 2006 are covered in more detail.
دانلود مقاله مروری بر انتقال حرارت جوششی نانو سیال ها A review of flow boiling heat transfer of nanofluids
The flow boiling heat transfer of nanofluids is an important research area which provides many
opportunities to explore new frontiers but also poses great challenges. This paper presents a
comprehensive review on the flow boiling heat transfer of nanofluids, with an emphasis on the heat
transfer coefficient (HTC), critical heat flux (CHF), pressure drop, nanofluid stability, flow and heat
transfer mechanism, and flow pattern and bubble dynamics. Most of the available articles have been
related to the first four topics. Studies related to the last two topics are rare, which are reviewed
because of their importance. The important achievements, inconsistence, and contradictions of the
existing research results are identified, and several topics worthy of attention for future investigations
دانلود مقاله مروری بر نقش سطوح حکاکی شده با لیزر روی انتقال حرارت جوششی A review on the role of laser textured surfaces on boiling heat transfer
Laser texturing can effectively obtain the desired surface features on metals through melting and solidification,
or through laser-based additive manufacturing techniques. In phase-change heat transfer applications, such
modified surfaces can be both beneficial and durable. Surface modification by ultrafast processing lasers alters
the heat transfer performances of boiling systems. This review summarizes the work leading to these technologies
and their role in influencing the performance of boiling systems. It first discusses the types and material
processing mechanism of lasers. Then, the applications of laser-textured surfaces in pool boiling and flow boiling
are discussed in detail. Different types of surface patterns can be fabricated on boiling surfaces depending on
experimental requirements. It is clearly evident that the design parameters and surface characteristics like
surface roughness, surface wettability, and porosity can be easily controlled by controlling the laser parameters.
Also, heat transfer performance of the textured surfaces changes as compared to the surfaces without any texturing.
As surface features generated as a result of laser texturing are permanent, the durability of the structures
can be increased with prolonged boiling performance. The review concludes with future recommendations for
identifying the research gaps and improving the heat transfer processes by laser-textured surfaces.
دانلود مقاله مرور خلاصه ای بر تاثیر پوشش های سطحی مختلف بر افزایش انتقال حرارت جوشش استخری Influence of different surface coatings on pool boiling heat transfer enhancement: A brief review
The below article provides a brief review of the previously published article on the improvement of pool
boiling heat transfer by modifying the surfaces in different coating techniques. Due to the surface modification
in different coating techniques, the active nucleation site density increases on surfaces, which
leads to enhancement of both heat transfer coefficient (HTC) and Critical Heat flux (CHF). Another reason
for enhancement of boiling heat transfer coefficient is enhancing the uniformity of coating over the heating
surface. This literature also incorporate how the wettability of the surface affect the HTC and CHF
related to different contact angle of working fluid. Different coating material also affects the wettability.
The coating time is found as one of the important parameter on this extensive survey on which affects the
pool Boiling heat Transfer a lot. The heat transfer performance of treated, untreated surface by different
coating techniques also incorporated in the article. The use of different coating techniques such as sintering,
brazing, spraying and electrodeposition was also incorporated in the literature. By using different
coating technique the coating can be formed on the substrate and on that surface Pool boiling occurs
which has a wide application in different industries.
Selection and of the scientific committee of the 10th International Conference of Materials Processing and
دانلود مقاله مروری بر کاربردهای نانومبردها و نانو روانسازها در سیستمهای تبرید، تهویه مطبوع و پمپ حرارتی Applications of nanorefrigerant and nanolubricants in refrigeration, air-conditioning and heat pump systems: A review
Nanorefrigerants are a special type of nanofluidswhich are mixtures of nanoparticles and refrigerants and have a
broad range of applications in diverse fields for instance refrigeration, air conditioning systems, and heat pumps.
In this paper thermal–physical properties of nanoparticles suspended in refrigerant and lubricating oils of
refrigerating systems were reviewed. The effects of nanolubricants on boiling and two phase flow phenomena
are presented as well. Based on results available in the literatures, it has been found that nanorefrigerants have
a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations
than conventional refrigerant. This can be considered as one of the key parameters for enhanced performance
for refrigeration and air conditioning systems. Because of its superior thermal performances, latest up to date
literatures on this property have been summarized and presented in this paper as well. The results indicate
that HFC134a and mineral oil with TiO2 nanoparticles work normally and safely in the refrigerator with better
performance. The energy consumption of the HFC134a refrigerant using mineral oil and nanoparticles mixture
as lubricant saved 26.1% energy with 0.1% mass fraction TiO2 nanoparticles compared to the HFC134a and POE
دانلود مقاله مروری تاریخی بر پیشرفتهای فناوری پمپ های حرارتی کمک شونده با انرژی خورشیدی در قرن بیست و یکم A chronological review of advances in solar assisted heat pump technology in 21st century
This paper presents a comprehensive review on developments and advances of Solar Assisted Heat Pump
technology reported in 21st century. Combination of thermal and photovoltaic solar collectors with heat pumps
has been widely used in recent decades for simultaneous heat, hot water and power generation for a broad range
of applications, from providing domestic and commercial buildings with heat and power to manufacturing and
agricultural applications. This review critically analyses the research reported in past two decades with particular
attention to the works with substantial importance for future development of the technology. Four distinctive
investigation periods were considered and key developments and dominant technologies at each period were
reported. The main novelties and breakthroughs in solar assisted heat pump technology, as identified by this
review, are: (1) The ban on R-12 refrigerant which lead to dominance of R-134A refrigerant for a wide range of
systems and applications, (2) Increasing interest in Solar-assisted Ground Source Heat Pumps following the
technological advances that made the utilization of such systems cost effective, (3) Advances in numerical
analysis methods and use of Artificial Intelligence applications in investigating performance and effectiveness of
various systems, and (4) Integrating the Photovoltaic/Thermal collectors with heat pumps for simultaneous heat
and power generation resulting in improved performance and reliable operation of systems under severe operating
دانلود مقاله مروری بر تولید انتروپی در میکرو کانالها A review of entropy generation in microchannels
در این مقاله مروری بر تحقیقات قبلی دربارۀ تولید انتروپی در میکروکانالها انجام گرفته است.
دانلود مقاله مروری بر کاربردهای دینامیک سیالات محاسباتی در صنایع غذایی Applications of computational fluid dynamics (CFD) in the food industry: a review
در این مقاله 20 صفحه ای دربارۀ کاربردهای دینامیک سیالات محاسباتی در صنایع غذایی صحبت شده است. فرایندهای
drying, sterilisation, refrigeration and mixing
بطور ویژه مورد توجه قرار گرفته اند.
دانلود مقاله معیار تخمین کارایی برای مبدلهای حرارتی (تبادلگرهای گرما) بر مبنای تحلیل قانون دوم Performance evaluation criteria for heat exchangers based on second law analysis
در این مقاله 17 صفحه ای، نحوه ارزیابی عملکرد تبادلگرهای گرما با استفاده از قانون دوم ترمودینامیک تشریح شده است.
در این مقاله روشهای تولید فومهای فلزی تشریح شده است. این فومها در کاربردهای مختلف صنعتی از جمله افزایش انتقال حرارت، فیلتراسیون و .... کاربردهای جالبی دارند.
در این مقاله 46 صفحه ای، مروری بر تحقیقات قبلی دربارۀ فناوری خشک کردن به روش اسپری انجام گرفته و نتایج تحقیقات قبلی تشریح شده است.
This article reviews spray drying technology for possible space applications like
processing of concentrated brines that are produced in evaporation/concentration
equipment with a goal of maximum water recovery. Spray drying principles of convection,
radiation and mixed convection-radiation are reviewed. Dryer designs and performance are
reviewed. Subjects of system dynamics and controls are discussed. Adaptations of existing
spray drying concepts to microgravity environment are suggested. Guidelines for design of
the spray drying systems for space applications are proposed.
دانلود مقاله خلاصه ای تاریخی از جدیدترین پیشرفتهای دینامیک سیالات تئوری و تجربی Brief History of the Early Development of Theoretical and Experimental Fluid Dynamics
2 Early Greek Science: Aristotle and Archimedes 2
3 DA Vinci’s Fluid Dynamics 2
4 The Velocity-Squared Law 3
5 Newton and the Sine-Squared Law 5
6 Daniel Bernoulli and the Pressure-Velocity
7 Henri Pitot and the Invention of the Pitot Tube 9
8 The High Noon of Eighteenth Century Fluid
Dynamics – Leonhard Euler and the Governing
Equations of Inviscid Fluid Motion 10
9 Inclusion of Friction in Theoretical Fluid
Dynamics: the Works of Navier and Stokes 11
10 Osborne Reynolds: Understanding Turbulent
11 The Circulation Theory of Lift: Kutta and
12 Ludwig Prandtl and His Boundary-Layer Theory 19
13 Summary 21
دانلود مقاله سلولهای خورشیدی باند متوسط : پیشرفتهای اخیر و جهتگیری های آینده Intermediate band solar cells: Recent progress and future directions
Extensive literature and publications on intermediate band solar cells (IBSCs) are reviewed. A
detailed discussion is given on the thermodynamics of solar energy conversion in IBSCs, the device
physics, and the carrier dynamics processes with a particular emphasis on the two-step inter-subband
absorption/recombination processes that are of paramount importance in a successful implementation
high-efficiency IBSC. The experimental solar cell performance is further discussed, which has been
recently demonstrated by using highly mismatched alloys and high-density quantum dot arrays and
superlattice. IBSCs having widely different structures, materials, and spectral responses are also
covered, as is the optimization of device parameters to achieve maximum performance.
The heart pumps blood to the human body. Artificial hearts are implanted in patients suffering from severe heart diseases. For the artificial heart system, we need to consider body fluids such as: Blood, intracellular fluids, extra cellular fluids, intravenous fluids and artificial (synthetic) blood. The use of anticoagulants (Heparin or Coumarin) is necessary in the implantation of an artificial organ. These act as blood thinners and prevent thromboembolism. Cardiovascular biomaterials are used to develop artificial heart valves, mechanical heart valves, pacemakers, vascular grafts, oxygenerators and cardiac assist systems (medical devices) like total artificial hearts, intra-aortic balloon pumps etc. Some of the biomaterials used in medicine are metals, polymers ceramics and hydrogels.
دانلود مقاله مروری بر فناوری روتور موجی و کاربردهای آن A Review of Wave Rotor Technology and Its Applications
The objective of this paper is to provide a succinct review of past and current research in
developing wave rotor technology. This technology has shown unique capabilities to
enhance the performance and operating characteristics of a variety of engines and machinery
utilizing thermodynamic cycles. Although there have been a variety of applications
in the past, this technology is not yet widely used and is barely known to engineers.
Here, an attempt is made to summarize both the previously reported work in the literature
and ongoing efforts around the world. The paper covers a wide range of wave rotor
applications including the early attempts to use wave rotors, its successful commercialization
as superchargers for car engines, research on gas turbine topping, and other
developments. The review also pays close attention to more recent efforts: utilization of
such devices in pressure-gain combustors, ultra-micro gas turbines, and water refrigeration
systems, highlighting possible further efforts on this topic. Observations and lessons
learnt from experimental studies, numerical simulations, analytical approaches, and
other design and analysis tools are presented. DOI: 10.1115/1.2204628