Energy and momentum balance equations: An approach to quantum transport in closed circuits

2002 ◽  
Vol 66 (3) ◽  
Author(s):  
Bart Sorée ◽  
Wim Magnus ◽  
Wim Schoenmaker
Keyword(s):  
Quantum Transport ◽  
Momentum Balance ◽  
Balance Equations ◽  
Energy And Momentum

Distributed and Nonsteady-State Model of an Air Cooler Working with R22 and R410A

2016 ◽  
Vol 24 (02) ◽  
pp. 1650008 ◽  
Author(s):  
R. O. Nunes ◽  
L. F. N. Castro ◽  
L. Machado ◽  
R. N. N. Koury
Keyword(s):  
Theoretical Data ◽  
Step Change ◽  
Montreal Protocol ◽  
Momentum Balance ◽  
Mass Energy ◽  
Balance Equations ◽  
Model Simulations ◽  
Nonsteady State ◽  
Air Cooler ◽  
Energy And Momentum

The restrictions imposed by Montreal Protocol for use of CFCs fluids and Kyoto Protocol to HCFCs have motivated researchers and the industry to seek new alternatives. Within this context, R410A has emerged as one of the most likely replacement of R22. The purpose of this work is to develop a numerical model of an air cooler to simulate its behavior operating under dynamic conditions loaded with R22 or R410A refrigerant. The model divides the air cooler in volumes control in which mass, energy, and momentum balance equations are applied and solved. Theoretical data obtained by model simulations repeated tendencies observed in experimental data taken from literature. Model simulations have also shown that for a step change in the inlet refrigerant mass flow, the superheating response of air cooler is almost the same when it is working with R22 or R410A refrigerant.

Model-Assisted Analysis of Simultaneous Paraffin and Asphaltene Deposition in Laboratory Core Tests

2005 ◽  
Vol 127 (4) ◽  
pp. 318-322 ◽  
Author(s):  
Shaojun Wang ◽  
Faruk Civan
Keyword(s):  
Experimental Data ◽  
Present Model ◽  
Momentum Balance ◽  
Balance Equations ◽  
Porosity And Permeability ◽  
Energy And Momentum ◽  
Assisted Analysis ◽  
Oil Gas ◽  
Deposition Models

A model for analysis and interpretation of the simultaneous deposition of paraffin and asphaltene in laboratory core tests is presented. This model incorporates the mass balance equations for the oil, gas, paraffin, and asphaltene pseudocomponents; the paraffin and asphaltene solubility and deposition models; the energy and momentum balance equations; and the porosity and permeability reduction models. This model is numerically solved and validated with two sets of laboratory experimental data. It is demonstrated that the present model satisfactorily represents the simultaneous deposition of paraffin and asphaltene and the resultant damage caused on the porosity and permeability of porous media. The model is used for determination of the various process parameters with the help of the experimental data obtained by laboratory core tests.

On Microfaceting Instability of Pt(110) Under Catalytic Oxidation of Adsorbed Co

1992 ◽  
Vol 263 ◽  
Author(s):  
M. Papoular
Keyword(s):  
Catalytic Oxidation ◽  
Oxidation Reaction ◽  
Nucleation And Growth ◽  
Point Of View ◽  
Momentum Balance ◽  
Layer By Layer ◽  
Adsorption Of Co ◽  
Specific Temperature ◽  
Energy And Momentum ◽  
Sawtooth Profile

ABSTRACTAs demonstrated by recent STM [1] and LEED [2] experiments the platinum (110) surface undergoes, at carbon monoxide submonolayer coverages, a phase transition from the 1 x 2 “missing-row” (reconstructed) state to the 1 x 1(bulk-like) state under specific temperature and partial-pressure conditions. The catalytic oxidation reaction CO + 1/2 → CO2 drives a microfaceting instability [3] [4] of the Pt(110) surface which ends up in a regular sawtooth profile with a period ≈ 200 Å, along the [110] direction.We introduce the idea that the rather extensive Pt mass transport, as involved in the process, could be energetically assisted by the reaction itself. Energy and momentum-balance considerations lead us to expect an energy ≲ 0.5 eV to be transferrable to thesubstrate. This should efficiently contribute to initiating the “scraping”process that leads to the microfaceted pattern.A simple model for nucleation and growth of facets is presented (see ref. 5), yielding characteristic times of order minutes (at T = 500 K), in fair agreement with experiment.Independently of the structural/catalytic problem, adsorption of CO at submonolayer coverages on, e.g., Pt(110) might be of interest from a surfactantphysics point of view (see ref. 6 for a very recent study on layer-by-layer homoepitaxial metal growth).

Generation of Tunable Necklace-Pattern Solitons in Two-Dimensional Dissipative System

2013 ◽  
Vol 339 ◽  
pp. 645-650
Author(s):  
Bin Liu ◽  
Shu Jing Li ◽  
Lin Ting Ma
Keyword(s):  
Landau Equation ◽  
Dissipative System ◽  
Gaussian Pulse ◽  
Two Dimensional ◽  
Balance Equations ◽  
Ginzburg Landau ◽  
Quintic Nonlinearity ◽  
Elliptical Ring ◽  
Energy And Momentum ◽  
Triangular Ring

We obtain necklace-pattern solitons (NPSs) from the same-pattern initial Gaussian pulse modulated by alternating azimuthal phase sections (AAPSs) of out-phase based on the two-dimensional (2D) complex Ginzburg-Landau equation with the cubic-quintic nonlinearity. The initial radially symmetrical Gaussian pulse can evolves into general necklace-rings solitons (NRSs). The number and distribution of pearls is tunable by adjusting sections-number and sections-distribution of AAPSs. In addition, we study the linear increased relationship between size of initial pulses and ring-radii of NRSs. Moreover, we predict the number-threshold of pearls in theoretical analysis by using of balance equations for energy and momentum. Final, we extend the research results to obtain arbitrary NPSs, such as elliptical ring, triangular-ring, and pentagonal ring.

Estimating Zonal Flow Contributions in Deep Water Assets From Pressure and Temperature Data

2017 ◽  
Author(s):  
A. Rashid Hasan ◽  
Rayhana N. Sohel ◽  
Xiaowei Wang
Keyword(s):  
Turbulent Flows ◽  
Deep Water ◽  
Fluid Pressure ◽  
Zonal Flow ◽  
Temperature Data ◽  
Sensitivity Analyses ◽  
Momentum Balance ◽  
Flow Profile ◽  
Flowing Fluid ◽  
Energy And Momentum

Producing hydrocarbon from deep water assets is extremely challenging and expensive. A good estimate of rates from multiple pay zones is essential for well monitoring, surveillance, and workover decisions. Such information can be gleaned from flowing fluid pressure and temperature; deep-water wells are often well instrumented that offers such data on a continuous basis. In this study a model is presented that estimates zonal flow contributions based on energy and momentum balances. Kinetic and heat energy coming from the reservoir fluid to the production tubing is accounted for in the model. The momentum balance for wellbore takes into account differing flow profile in laminar and turbulent flows. In addition, when sandface temperature data are not available, a recently developed analytical model to estimate the effect of Joule-Thompson expansion on sandface temperature was used to estimate sandface temperature from reservoir temperature. The model developed can be applied to any reservoir with multiple pay zones and is especially useful for deep-water assets where production logging is practically impossible. Available field data for multiphase flow was used to validate the model. Sensitivity analyses were performed that showed accurate temperature data is essential for the model to estimate zonal contribution accurately.

Dynamical modelling of an anaerobic digestion fluidized bed reactor

1997 ◽  
Vol 36 (5) ◽  
pp. 285-292 ◽  
Author(s):  
Benjamin Bonnet ◽  
Denis Dochain ◽  
Jean-Philippe Steyer
Keyword(s):  
Fluidized Bed ◽  
Solid Phase ◽  
Biofilm Reactor ◽  
Momentum Balance ◽  
Balance Equations ◽  
Biological Variables ◽  
Dynamical Simulation ◽  
Model Derivation ◽  
The Stability ◽  
Bed Expansion

One of the main difficulties in modelling a Fluidized Bed Biofilm Reactor (FBBR) is to take into account hydraulic phenomena (such as bed expansion) and its interactions with the biological variables. In this paper, we shall present a dynamical model of the process, analyse the stability of the hydrodynamics and illustrate its performances in simulation. A key feature of the model is that it combines mass balance of the process components with momentum balance equations in order to emphasise the different hydrodynamics of the liquid phase and of the solid phase, and the interactions between both phases. The model derivation finally leads to a set of partial differential equations (PDE). This model is intended to be used as a basis for the derivation of controllers and for dynamical simulation.

scholarly journals THE INFLUENCE OF “INJECTED” AND “THERMAL” MAGNONS ON A SPIN WAVE CURRENT AND DRAG EFFECT IN HYBRID STRUCTURES

2018 ◽  
Vol 185 ◽  
pp. 01022
Author(s):  
Igor Lyapilin ◽  
Mikhail Okorokov
Keyword(s):  
Spin Wave ◽  
Metal Structure ◽  
Relaxation Mechanism ◽  
Seebeck Effect ◽  
Hybrid Structures ◽  
Momentum Balance ◽  
Drag Effect ◽  
Balance Equations ◽  
Spin Seebeck Effect ◽  
Magnetic Insulator

The formation of the two: injected and thermally excited, different in energies magnon subsystems and the influence of its interaction with phonons and between on drag effect under spin Seebeck effect conditions in the magnetic insulator part of the metal/ferromagnetic insulator/metal structure is studied. The analysis of the macroscopic momentum balance equations of the systems of interest conducted for different ratios of the drift velocities of the magnon and phonon currents show that the injected magnons relaxation on the thermal ones is possible to be dominant over its relaxation on phonons. This interaction will be the defining in the forming of the temperature dependence of the spin-wave current under spin Seebeck effect conditions, and inelastic part of the magnon-magnon interaction is the dominant spin relaxation mechanism.

scholarly journals CONTRIBUTIONS TO THE MARINE PROPELLERS HYDRODYNAMIC DESIGN

2014 ◽  
Vol 13 (2) ◽  
pp. 41
Author(s):  
B. I. Favacho ◽  
J. R. P. Vaz ◽  
A. L. A. Mesquita
Keyword(s):  
Control Volume ◽  
Computational Cost ◽  
Momentum Balance ◽  
Marine Propellers ◽  
Energy And Momentum ◽  
Thrust And Torque ◽  
The Mathematical Model ◽  
Low Computational Cost ◽  
Bem Theory ◽  
Good Agreement

The navigation in Amazon region is very important due to the length of navigable rivers and the lack of alternative road network, as well as being a form of transportation costless for the flow of agricultural and manufacturing production. This kind of transportation present social, economic and technological importance for this region. Thus, this work objective to develop a mathematical approach for the marine propellers design, using a formulation for chord and pitch angle optimization, taken into account the equations of mass, energy and momentum balance for the theoretical calculation of thrust and torque relationships on an annular control volume, ie, the mathematical model is based in the Blade Element Momentum (BEM) theory. The proposed hydrodynamic model present low computational cost and it is easy to implement. The results are compared with classical Glauert's theory and the experimental data of the Wageningen B3-50 propeller, presenting good agreement.

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