scholarly journals Modelling heat and mass transfers in DCMD using compressible membranes

2012 ◽  
Vol 387-388 ◽  
pp. 7-16 ◽  
Author(s):  
Jianhua Zhang ◽  
Stephen Gray ◽  
Jun-De Li
Keyword(s):  
Mass Transfers

COUPLED HEAT AND MASS TRANSFERS IN POROUS MEDIA: NUMERICAL SIMULATION FOR SOIL-BUILDING TRANSFERS

1994 ◽  
Author(s):  
L. M. Chounet ◽  
D. Hilhorst ◽  
C. Jouron ◽  
Y. Kelanemer ◽  
P. Nicolas
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Mass Transfers

GLOBAL RAINBOW REFRACTOMETRY DEVELOPMENT TO CHARACTERIZE HEAT AND MASS TRANSFERS IN A TWO PHASE FLOW

Equipment ◽  
2006 ◽  
Author(s):  
P. Lemaitre ◽  
E. Porcheron ◽  
L. Bouilloux ◽  
G. Grehan
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Mass Transfers ◽  
Rainbow Refractometry

scholarly journals Aqueous phenol and ethylene glycol solutions in electrohydrodynamic liquid bridging

2011 ◽  
Vol 9 (3) ◽  
pp. 391-403 ◽  
Author(s):  
Mathias Eisenhut ◽  
Xinghua Guo ◽  
Astrid Paulitsch-Fuchs ◽  
Elmar Fuchs
Keyword(s):  
Mass Transport ◽  
Ethylene Glycol ◽  
Bisphenol A ◽  
Anodic Oxidation ◽  
High Voltage ◽  
Electrochemical Behavior ◽  
Pure Water ◽  
Passivation Layer ◽  
Mass Transfers ◽  
Electrophoretic Transport

AbstractThe formation of aqueous bridges containing phenol and ethylene glycol as well as bisphenol-A, hydrochinone and p-cresol under the application of high voltage DC (“liquid bridges”) is reported. Detailed studies were made for phenol and glycol with concentrations from 0.005 to 0.531 mol L−1. Conductivity as well as substance and mass transfers through these aqueous bridges are discussed and compared with pure water bridges. Previously suggested bidirectional mass transport is confirmed for the substances tested. Anodic oxidation happens more efficiently when phenol or glycol are transported from the cathode to the anode since in this case the formation of a passivation layer or electrode poisoning are retarded by the electrohydrodynamic (EHD) flow. The conductivity in the cathode beaker decreases in all experiments due to electrophoretic transport of naturally dissolved carbonate and bicarbonate to the anode. The observed electrochemical behavior is shortly discussed and compared to known mechanisms.

Towards Low-NOx Operation in a Complex Burner: Optimization of an Annular Trapped Vortex Combustor

2013 ◽  
Author(s):  
Pradip Xavier ◽  
Bruno Renou ◽  
Gilles Cabot ◽  
Mourad A. Boukhalfa ◽  
Michel Cazalens
Keyword(s):  
Acoustic Energy ◽  
Combustion Instabilities ◽  
Chemical Parameters ◽  
Hot Gas ◽  
Highly Sensitive ◽  
Stable Flame ◽  
Mass Transfers ◽  
Gas Expansion ◽  
Trapped Vortex ◽  
Original Configuration

This paper focuses on optimizing an innovative annular Lean Premixed staged burner, following the Trapped Vortex Combustor concept. The latter consists of a lean main flame stabilized by passing past a rich cavity pilot flame. Unfortunately, this configuration is highly sensitive to combustion instabilities and the flame is not well stabilized. This work consists of adjusting aerodynamic variables, chemical parameters and burner geometry to reach a “low-NOx” operation while reducing other pollutants and getting a stable flame. Results show that stability is reached when mass transfers between main and cavity zones are reduced. Then, the main bulk velocity is increased to reduce the cavity thermal expansion, due to the hot gas expansion. In addition, the cavity flow rate is reduced to prevent from penetrating and disturbing the main flow. Re-arranging injections in the cavity also avoid local unsteady equivalence ratios, which creates an unsteady heat release and combustion with pulses. Regarding NOx, a leaner main flame combined with a sufficiently rich cavity mixture creates local stoichiometric zones at the interface between the cavity and the main zone. The latter point is found to be a good anchoring mechanism. Compared with the original configuration, a stable point of operation is found: acoustic energy is reduced by an order of 100, NOx level is less than 0.4 g/kgfuel, CO is cut by 93% with no more Unburned Hydro-Carbons.

scholarly journals Infrared Thermospectroscopic Imaging of Heat and Mass Transfers in Laminar Microfluidic Reactive Flows

2021 ◽  
pp. 100166
Author(s):  
S. Chevalier ◽  
J.-N. Tourvieille ◽  
A. Sommier ◽  
C. Pradère
Keyword(s):  
Reactive Flows ◽  
Mass Transfers

Stability analysis on dual solutions of second- grade fluid flow with heat and mass transfers over a stretching sheet

2021 ◽  
Vol 8 (2) ◽  
Author(s):  
D. Dey ◽  
R. Borah
Keyword(s):  
Fluid Flow ◽  
Stability Analysis ◽  
Lorentz Force ◽  
Drag Force ◽  
Dual Solutions ◽  
Second Grade ◽  
Second Grade Fluid ◽  
Independent Case ◽  
Grade Fluid ◽  
Mass Transfers

Stability on dual solutions of second-grade fluid flow over a stretching surface with simultaneous thermal and mass diffusions has been studied. The fluid flow is governed by Lorentz force and energy dissipation due to viscosity. Lorentz force is generated due to the application of magnetic field along the transverse direction. In methodology, suitable similarity transformation and MATLAB built-in bvp4c solver technique have been adopted. Effects of some flow parameters are exhibited through figures and tables and a special emphasis is given on the existence of dual solutions. A stability analysis is executed to determine the stable and physically achievable solutions. For the laminar flow, the drag force on the surface for the time-independent case is reduced due to amplifying values of But, it enhances the drag force for the time-dependent case. This shows the effectiveness of the first solution (during steady case) over the unsteady case.

scholarly journals Time-Space Characterization of Wellbore-Cement Alteration by CO2-Rich Brine

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 490
Author(s):  
Maria Garcia-Rios ◽  
Philippe Gouze
Keyword(s):  
Numerical Models ◽  
Reaction Rates ◽  
Diffusion Reaction ◽  
Cement Matrix ◽  
Relative Distribution ◽  
Reaction Fronts ◽  
Time Space ◽  
Mass Transfers ◽  
Dissolution And Precipitation ◽  
Diffusion Properties

The risk of CO2 leakage from damaged wellbore is identified as a critical issue for the feasibility and environmental acceptance of CO2 underground storage. For instance, Portland cement can be altered if flow of CO2-rich water occurs in hydraulic discontinuities such as cement-tubing or cement-caprock interfaces. In this case, the raw cement matrix is altered by diffusion of the solutes. This fact leads to the formation of distinctive alteration fronts indicating the dissolution of portlandite, the formation of a carbonate-rich layer and the decalcification of the calcium silicate hydrate, controlled by the interplay between the reaction kinetics, the diffusion-controlled renewing of the reactants and products, and the changes in the diffusion properties caused by the changes in porosity induced by the dissolution and precipitation mechanisms. In principle, these mass transfers can be easily simulated using diffusion-reaction numerical models. However, the large uncertainties of the parameters characterizing the reaction rates (mainly the kinetic and thermodynamic coefficients and the evolving reactive surface area) and of the porosity-dependent diffusion properties prevent making reliable predictions required for risk assessment. In this paper, we present the results of a set of experiments consisting in the alteration of a holed disk of class-G cement in contact with a CO2-rich brine at reservoir conditions (P = 12 MPa and T = 60 °C) for various durations. This new experimental protocol allows producing time-resolved data for both the spatially distributed mass transfers inside the cement body and the total mass transfers inferred from the boundary conditions mass balance. The experimental results are used to study the effect of the fluid salinity and the pCO2 on the overall reaction efficiency. Experiments at high salinity triggers more portlandite dissolution, thinner carbonate layers, and larger alteration areas than those at low salinity. These features are accompanied with different spatial distribution of the alteration layers resulting from a complex interplay between salinity-controlled dissolution and precipitation mechanisms. Conversely, the effect of the pCO2 is more intuitive: Increasing pCO2 results in increasing the overall alteration rate without modifying the relative distribution of the reaction fronts.

Transient Analysis and Performance Prediction of a Solid Adsorption Solar Refrigerator

Solar Energy ◽  
2005 ◽  
Author(s):  
Emmanuel E. Anyanwu ◽  
Nnamdi V. Ogueke
Keyword(s):  
Performance Prediction ◽  
Transient Analysis ◽  
Adsorption Process ◽  
Design Tool ◽  
Coefficient Of Performance ◽  
Collector Plate ◽  
Tube Arrangement ◽  
And Performance ◽  
Mass Transfers ◽  
The Mathematical Model

The transient analysis and performance prediction of a solid adsorption solar refrigerator, using activated carbon/methanol adsorbent/adsorbate pair are presented. The mathematical model is based on the thermodynamics of the adsorption process, heat transfer in the collector plate/tube arrangement, and heat and mass transfers within the adsorbent/adsorbate pair. Its numerical model developed from finite element transformation of the resulting equations computes the collector plate and tube temperatures to within 5°C. The condensate yield and coefficient of performance, COP were predicted to within 5% and 9%, respectively. The resulting evaporator water temperature was also predicted to within 4%. Thus the model is considered a useful design tool for the refrigerator to avoid costly experimentation.

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