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787 full-text articles. Page 28 of 29.

13 - جانمايي مناسب وسايل احتراقي؛ راهکاري در جهت بهبود کيفيت هواي داخل, Chamran Nowrouzi, Mehdi Maerefat, Alireza Zolfaghari 2010 University of Birjand

13 - جانمايي مناسب وسايل احتراقي؛ راهکاري در جهت بهبود کيفيت هواي داخل, Chamran Nowrouzi, Mehdi Maerefat, Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.


Modeling And Numerical Investigation Of Hot Gas Defrost On A Finned Tube Evaporator Using Computational Fluid Dynamics, Oai The Ha 2010 California Polytechnic State University, San Luis Obispo

Modeling And Numerical Investigation Of Hot Gas Defrost On A Finned Tube Evaporator Using Computational Fluid Dynamics, Oai The Ha

Master's Theses and Project Reports

Defrosting in the refrigeration industry is used to remove the frost layer accumulated on the evaporators after a period of running time. It is one way to improve the energy efficiency of refrigeration systems. There are many studies about the defrosting process but none of them use computational fluid dynamics (CFD) simulation. The purpose of this thesis is (1) to develop a defrost model using the commercial CFD solver FLUENT to simulate numerically the melting of frost coupled with the heat and mass transfer taking place during defrosting, and (2) to investigate the thermal response of the evaporator and the ...


Do Surfaces With Mixed Hydrophilic And Hydrophobic Areas Enhance Pool Boiling?, Amy Rachel Betz, Jie Xu, Huihe Qiu, Daniel Attinger 2010 Columbia University

Do Surfaces With Mixed Hydrophilic And Hydrophobic Areas Enhance Pool Boiling?, Amy Rachel Betz, Jie Xu, Huihe Qiu, Daniel Attinger

Daniel Attinger

We demonstrate that smooth and flat surfaces combining hydrophilic and hydrophobicpatterns improve pool boiling performance. Compared to a hydrophilicsurface with 7° wetting angle, the measured critical heat flux and heat transfer coefficients of the enhanced surfaces are, up to respectively, 65% and 100% higher. Different networks combining hydrophilic and hydrophobic regions are characterized. While all tested networks enhance the heat transfer coefficient, large enhancements of critical heat flux are typically found for hydrophilic networks featuring hydrophobic islands. Hydrophilic networks indeed are shown to prevent the formation of an insulating vapor layer.


A Short-Distance Integral-Balance Solution To A Strong Subdiffusion Equation: A Weak Power-Law Profile, Jordan Hristov 2010 University of Chemical Technology and Metallurgy

A Short-Distance Integral-Balance Solution To A Strong Subdiffusion Equation: A Weak Power-Law Profile, Jordan Hristov

Jordan Hristov

The work presents an integral solution of the time-fractional subdiffusion through a preliminary defined profile with unknown coefficients and the concept of penetration layer well known from the heat diffusion The profile satisfies the boundary conditions imposed at the boundary of the boundary layer in a weak form that allows its coefficients to be expressed through the boundary layer depth as unique parameter describing the profile. The technique is demonstrated by a solution of a time fractional subdiffusion equation in rectilinear 1-D conditions.


Energetyka Niskoemisyjna, Wojciech M. Budzianowski 2010 Wroclaw University of Technology

Energetyka Niskoemisyjna, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Can Segmented Flow Enhance Heat Transfer In Microchannel Heat Sinks?, Amy Rachel Betz, Daniel Attinger 2010 Columbia University

Can Segmented Flow Enhance Heat Transfer In Microchannel Heat Sinks?, Amy Rachel Betz, Daniel Attinger

Daniel Attinger

Liquid cooling is an efficient way to remove heat fluxes with magnitudes up to 10,000 W/cm2. One limitation of current single-phase microchannel heat sinks is the relatively low Nusselt number, due to laminar flow. In this work, we experimentally investigate how to enhance the Nusselt number with the introduction of segmented flow. The segmented flow pattern was created by the periodic injection of air bubbles through a T-junction into water-filled channels. We designed a polycarbonate heat sink consisting of an array of seven parallel microchannels each with a square cross-section 500 μm wide. We show that segmented flow ...


Interfacial Temperature Measurements, High-Speed Visualization And Finite-Element Simulations Of Droplet Impact And Evaporation On A Solid Surface, Rajneesh Bhardwaj, Jon P. Longtin, Daniel Attinger 2010 Columbia University

Interfacial Temperature Measurements, High-Speed Visualization And Finite-Element Simulations Of Droplet Impact And Evaporation On A Solid Surface, Rajneesh Bhardwaj, Jon P. Longtin, Daniel Attinger

Daniel Attinger

The objective of this work is to investigate the coupling of fluid dynamics, heat transfer and mass transfer during the impact and evaporation of droplets on a heated solid substrate. A laser-based thermoreflectance method is used to measure the temperature at the solid–liquid interface, with a time and space resolution of 100 μs and 20 μm, respectively. Isopropanol droplets with micro- and nanoliter volumes are considered. A finite-element model is used to simulate the transient fluid dynamics and heat transfer during the droplet deposition process, considering the dynamics of wetting as well as Laplace and Marangoni stresses on the ...


Performance Comparison Of Control Methods For Tankless Water Heaters, David P. Yuill, Andrew H. Coward, Gregor P. Henze 2010 University of Nebraska-Lincoln

Performance Comparison Of Control Methods For Tankless Water Heaters, David P. Yuill, Andrew H. Coward, Gregor P. Henze

David Yuill

Tankless water heaters (TWH) have several advantages and disadvantages when compared with storage water heaters. One disadvantage is that the outlet temperature of the water is difficult to control. To address this problem, the authors apply seven different control approaches and con- duct experiments to test the effectiveness of each approach. The experiments are carried out on a commercially available electric TWH, using a test method and apparatus developed by the authors. The seven approaches include various configurations of feedback or feed-forward con- trol, or both. One fairly simple approach devised in this project combines feedback and feed-forward control. This ...


Absolute Ground-State Nitrogen Atom Density In A N2/Ch4 Late Afterglow: Talif Experiments And Modelling Studies, Et. Es-sebbar, M.-C. Gazeau, Y. Benilan, A. Jolly, C D. Pintassilgo 2010 Paul Scherrer Institute (PSI)

Absolute Ground-State Nitrogen Atom Density In A N2/Ch4 Late Afterglow: Talif Experiments And Modelling Studies, Et. Es-Sebbar, M.-C. Gazeau, Y. Benilan, A. Jolly, C D. Pintassilgo

Dr. Et-touhami Es-sebbar

Following a first study on a late afterglow in flowing pure nitrogen post discharge, we report new two-photon absorption laser-induced fluorescence (TALIF) measurements of the absolute ground-state atomic nitrogen density N(4S) and investigate the influence of methane introduced downstream from the discharge by varying the CH4 mixing ratio from 0% up to 50%. The N (4S) maximum density is about 2.2 × 1015 cm−3 in pure N2 for a residence time of 22 ms and does not change significantly for methane mixing ratio up to ~15%, while above, a drastic decrease is observed. The influence of the residence ...


7 - استفاده از روش معکوس برای طراحی حرارتی يک اتاق مسکونی، به منظور ايجاد شرايط آسايش حرارتی, Reza Imani, Mehdi Maerefat, Farshad Kowsari, Alireza Zolfaghari 2010 University of Birjand

7 - استفاده از روش معکوس برای طراحی حرارتی يک اتاق مسکونی، به منظور ايجاد شرايط آسايش حرارتی, Reza Imani, Mehdi Maerefat, Farshad Kowsari, Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.


Experimental And Theoretical Studies On Nitrogen Plasma And Methane Photolysis: Implications For Laboratory Simulations Of Titan’S Atmosphere, M-C. Gazeau, Y. Benilan, E. Arzoumanian, Et. Es-sebbar, A. Jolly 2010 Paul Scherrer Institute (PSI)

Experimental And Theoretical Studies On Nitrogen Plasma And Methane Photolysis: Implications For Laboratory Simulations Of Titan’S Atmosphere, M-C. Gazeau, Y. Benilan, E. Arzoumanian, Et. Es-Sebbar, A. Jolly

Dr. Et-touhami Es-sebbar

No abstract provided.


Spectroscopic Studies Applied To Uvis Observations Of Titan, Y. Benilan, F. Capalbo, Et. Es-sebbar, N. Fray, A. Jolly, M-C. Gazeau, J-C. Guillemin, M. Schwell 2010 Paul Scherrer Institute (PSI)

Spectroscopic Studies Applied To Uvis Observations Of Titan, Y. Benilan, F. Capalbo, Et. Es-Sebbar, N. Fray, A. Jolly, M-C. Gazeau, J-C. Guillemin, M. Schwell

Dr. Et-touhami Es-sebbar

No abstract provided.


Talif Investigation And Modelling Of The Absolute N(4s) Density In A N2-Ch4 Late Afterglow, C.D. Pintassilgo, Et. Es-sebbar, Y. Benilan, M-C. Gazeau, A. Jolly 2010 Paul Scherrer Institute (PSI)

Talif Investigation And Modelling Of The Absolute N(4s) Density In A N2-Ch4 Late Afterglow, C.D. Pintassilgo, Et. Es-Sebbar, Y. Benilan, M-C. Gazeau, A. Jolly

Dr. Et-touhami Es-sebbar

The purpose of the present work is the experimental and numerical study of the absolute ground-state nitrogen atoms density N(4S) in the late afterglow of a pure N2 flowing microwave discharge in which different amounts of CH4 have been injected at 25 cm downstream from the nitrogen discharge. The absolute N(4S) concentrations have been measured using Two-photon Absorption Laser-Induced Fluorescence (TALIF), while a detailed kinetic model has been developed to simulate both the discharge and the post-discharge regions. Theoretical predictions are then compared to experimental measurements.


Combined Experimental And Theoretical Studies On Methane Photolysis At 121.6 Nm And 248 Nm- Implications On A Program Of Laboratory Simulations Of Titan’S Atmosphere, C. Romanzin, E. Arzoumanian, Et. Es-sebbar, A. Jolly, S. Perrier, M.-C. Gazeau, Y. Bénilan 2010 Paul Scherrer Institute (PSI)

Combined Experimental And Theoretical Studies On Methane Photolysis At 121.6 Nm And 248 Nm- Implications On A Program Of Laboratory Simulations Of Titan’S Atmosphere, C. Romanzin, E. Arzoumanian, Et. Es-Sebbar, A. Jolly, S. Perrier, M.-C. Gazeau, Y. Bénilan

Dr. Et-touhami Es-sebbar

Methane is, together with N2, the main precursor of Titan’s atmospheric chemistry. In our laboratory, we are currently developing a program of laboratory simulations of Titan’s atmosphere, where methane is intended to be dissociated by multiphotonic photolysis at 248 nm. A preliminary study has shown that multiphotonic absorption of methane at 248 nm is efficient and leads to the production of hydrocarbons such as C2H2 (Romanzin et al., 2008). Yet, at this wavelength, little is known about the branching ratios of the hydrocarbon radicals (CH3, CH2 and CH) and their following photochemistry. This paper thus aims at investigating ...


Numerical Methods For Simulating Multiphase Electrohydrodynamic Flows With Application To Liquid Fuel Injection, Bret Van Poppel 2010 United States Military Academy

Numerical Methods For Simulating Multiphase Electrohydrodynamic Flows With Application To Liquid Fuel Injection, Bret Van Poppel

West Point ETD

One approach to small-scale fuel injection is to capitalize upon the benefits of electrohydrodynamics (EHD) and enhance fuel atomization. There are many potential advantages to EHD aided atomization for combustion, such as smaller droplets, wider spray cone, and the ability to control and tune the spray for improved performance. Electrohydrodynamic flows and sprays have drawn increasing interest in recent years, yet key questions regarding the complex interactions among electrostatic charge, electric fields, and the dynamics of atomizing liquids remain unanswered. The complex, multi-physics and multi-scale nature of EHD atomization processes limits both experimental and computational explorations.

In this work, novel ...


Temperature-Dependent Photoabsorption Cross-Section Of Cyano-Diacetylene In The Vacuum Uv, N. Fray, Y. Bénilan, M.-C. Gazeau, A. Jolly, M. Schwell, E. Arzoumanian, Et. Es-sebbar, T. Ferradaz, J.- C. Guillemin 2010 Paul Scherrer Institute (PSI)

Temperature-Dependent Photoabsorption Cross-Section Of Cyano-Diacetylene In The Vacuum Uv, N. Fray, Y. Bénilan, M.-C. Gazeau, A. Jolly, M. Schwell, E. Arzoumanian, Et. Es-Sebbar, T. Ferradaz, J.- C. Guillemin

Dr. Et-touhami Es-sebbar

Using synchrotron radiation as a tunable VUV light source, we have measured, for the first time, the absolute photoabsorption cross sections of HC5N with a spectral resolution of 0.05 nm in the region between 80 and 205 nm from 233 to 298 K. The measured cross sections are used to predict the HC5N photodestruction rate in the solar system and to model a transmission spectrum in Titan's atmosphere. Comparing the latter with that acquired by the Ultraviolet Imaging Spectrograph on board the Cassini spacecraft, we have determined an upper limit of 2.7 × 10−5 on the HC5N ...


Heat-Balance Integral To Fractional (Half-Time) Heat Diffusion Sub-Model, Jordan Hristov 2010 University of Chemical Technology and Metallurgy

Heat-Balance Integral To Fractional (Half-Time) Heat Diffusion Sub-Model, Jordan Hristov

Jordan Hristov

The fractional (half-time) sub-model of the heat diffusion equation, known as Dirac-like evolution diffusion equation has been solved by the heat-balance integral method and a parabolic pro file with unspecified exponent. The fractional heat-balance integral method has been tested with two classic examples: fixed temperature and fixed flux at the boundary. The heat-balance technique allows easily the convolution integral of the fractional half-time derivative to be solved as a convolution of the time-independent approximating function. The fractional sub-model provides an artificial boundary condition at the boundary that closes the set of the equations required to express all parameters of the ...


Irrigation Leak Detection: Using Flow Rate Sensors To Detect Breaks In An Irrigation System, Adam Openshaw, Kalvin Vu 2010 California Polytechnic State University - San Luis Obispo

Irrigation Leak Detection: Using Flow Rate Sensors To Detect Breaks In An Irrigation System, Adam Openshaw, Kalvin Vu

Computer Engineering

This report details the exploration and invention of a mechanism that can detect breaks in an irrigation system. With the ultimate goal of conserving water, we have designed an inexpensive, self sustaining flow rate monitor that can be used to identify anomalies in an irrigation system and wirelessly communicate the status of the system to a base station. Our implementation can also determine the direction of the anomaly based on the nature of the anomaly itself. This means that multiple monitors can be used to pinpoint the location of a break within the system in addition to merely detecting its ...


Pg&E Flow Loop Simulator, Cole Brooks, Seth Berger, Ben Thacker 2010 California Polytechnic State University - San Luis Obispo

Pg&E Flow Loop Simulator, Cole Brooks, Seth Berger, Ben Thacker

Mechanical Engineering

PG&E’s Diablo Canyon Power Plant requested a full-sized Flow Loop Simulator to train technicians by giving them hands-on experience. The basic design requirements were established to determine the scope of the project and develop the specific characteristics of the system. The detailed system design is composed of a piping schematic, a three-dimensional layout of the system components and piping, and a skid structure for the support and transportation of the system. Heat transfer and fluid mechanics were used to analyze the system to size components.


Development Of Hydrogen Direct Injection For Conversion Of Internal Combustion Engines, Maxwell A. Wilson 2010 University of Nevada Las Vegas

Development Of Hydrogen Direct Injection For Conversion Of Internal Combustion Engines, Maxwell A. Wilson

UNLV Theses, Dissertations, Professional Papers, and Capstones

The trend toward usage of vehicles that operate on alternative, renewable forms of energy storage has generated areas for development of new products that will facilitate implementation of new automotive fuel systems. As the reality of a hydrogen-fueled economy emerges, intermediate technologies may be necessary for the transition between hydrocarbon fueled internal combustion engines and hydrogen powered fuel cells. The University of Nevada Las Vegas Center for Energy Research has developed a method for converting the common hydrocarbon fueled internal combustion engine to hydrogen direct injected fueling. This thesis describes the second phase of development and involves the design, fabrication ...


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