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    Modeling of Heat Transfer Mechanism in Porous Media Combustion Chamber

    , M.Sc. Thesis Sharif University of Technology Arzhangnia, Yousef (Author) ; Ghafourian Morshed Yazdi, Akbar (Supervisor) ; Saeedi, Mohammad Hassan (Supervisor)
    Combustion procedure in porous media is of great importance and also has numerous technical applications. Currently several usages of porous burners in thermodynamic engineering and thermal industries have been identified, in which they perform based on stabilized combustion in porous media. Among the advantages that porous burners have over conventional burners are pollution reduction, decrease in burner dimension, enhanced flame stabilization and also noise reduction.
    According to physical and chemical attributes of porous material, combustion can occur in one of the three main types of media including: inert, catalytic, combustible. The concepts mentioned in this proposal are... 

    Second law analysis of slip flow forced convection through a parallel plate microchannel

    , Article Nanoscale and Microscale Thermophysical Engineering ; Volume 14, Issue 4 , 2010 , Pages 209-228 ; 15567265 (ISSN) Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    In the present work, the second law of thermodynamics analysis has been carried out for steady-state fully developed laminar gas flow in a parallel plate microchannel with asymmetrically heated walls. The rarefaction effects as well as viscous heating effects are taken into consideration. Closed-form expressions are obtained for velocity and temperature distributions and entropy generation rates. The results demonstrate that increasing values of the wall heat fluxes ratio result in greater entropy generation for positive Brinkman numbers, whereas the opposite is true for negative values of Brinkman. However, the effect of the wall heat fluxes ratio on entropy generation becomes insignificant... 

    Desulfurization of liquid-phase Butane by zeolite molecular sieve 13X in a fixed bed: Modeling, simulation, and comparison with commercial-scale plant data

    , Article Energy and Fuels ; Volume 22, Issue 1 , 2008 , Pages 570-575 ; 08870624 (ISSN) Shams, A ; Molaei Dehkordi, A ; Goodarznia, I ; Sharif University of Technology
    This paper deals with the modeling and simulation of binary liquid-phase adsorption of methyl mercaptan and hydrogen sulfide from a liquid butane stream by zeolite molecular sieve 13X in a fixed bed. The model equations account for the effect of axial dispersion and the inter- and intraparticle, mass-transfer resistances at isothermal operating conditions. Orthogonal collocation and Gill's fourth-order Runge-Kutta methods were used to solve the dimensionless general forms of the 4N-eoupled ordinary differential equations for simultaneous adsorption of the solutes by the adsorbent in a fixed bed. The model predictions were compared to the commercial-scale plant data of an Iranian... 

    Entropy generation for forced convection in a porous channel with isoflux or isothermal walls

    , Article International Journal of Exergy ; Volume 5, Issue 1 , 2008 , Pages 78-96 ; 17428297 (ISSN) Hooman, K ; Hooman, F ; Mohebpour, S. R ; Sharif University of Technology
    Inderscience Publishers  2008
    A numerical study is reported to investigate the entropy generation due to forced convection in a parallel plate channel filled by a saturated porous medium. Two different thermal boundary conditions are considered being isoflux and isothermal walls. Effects of the Poclet number, the porous medium shape factor, the dimensionless temperature difference for isothermal walls, the dimensionless heat flux for isoflux walls, and the Brinkman number on the Bejan number as well as the local and average dimensionless entropy generation rate are examined. Copyright © 2008 Inderscience Enterprises Ltd  

    Coupling Flow and Geochemistry for Numerical Simulation of Low Salinity/Smart Waterflooding in Carbonates

    , M.Sc. Thesis Sharif University of Technology Alipour, Sina (Author) ; Ayatollahi, Shahab (Supervisor) ; Mahani, Hassan (Supervisor)
    Due to the decrease in oil reserves in the world, increasing population and the growing demands for oil consumption in the world, increasing the oil recovery from oil reservoirs has become more important. Increasing the amount of oil production efficiency by using low salinity water/modified salinity water has been highly appreciated during the last two decades. Low-salt water is a new method, due to its advantages such as low cost, simplicity of operation and low environmental hazards. It is believed that low salinity water can alter the rock wettability from a more oil-wetting state to a more water-wetting state. In order to be able to predict the performance of low salinity water... 

    Rarefaction effects on gas mixing in micro- and nanoscales

    , Article ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2016, 4 January 2016 through 6 January 2016 ; Volume 1 , 2016 ; 9780791849651 (ISBN) Darbandi, M ; Sabouri, M ; Heat Transfer Division ; Sharif University of Technology
    American Society of Mechanical Engineers  2016
    We present the rarefaction effects on diffusive mass transport in micro- and nanoscales using the results of direct simulation Monte Carlo DSMC method. Unlike the previous investigations, the momentum and heat contributions are eliminated from the computations via uniform velocity, pressure, and temperature field considerations. The effects of global Knudsen number on the diffusion phenomenon are studied for the same Peclet number and a unique mixer shape. The results indicate that there is considerable weakening in diffusion mechanism for high Knudsen number cases. As a result, the non-dimensional diffusive mass fluxes would decrease and the non-dimensional mixing length would increase as... 

    A new non-dimensional parameter to obtain the minimum mixing length in tree-like concentration gradient generators

    , Article Chemical Engineering Science ; Volume 195 , 2019 , Pages 120-126 ; 00092509 (ISSN) Rismanian, M ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
    Elsevier Ltd  2019
    Microfluidic-based concentration gradient generators (CGGs) have a number of applications in chemical, biological and pharmaceutical studies. Thus, precise design of the microfluidic system is crucial to maintaining the desired concentration gradient in microchannels. One of the design considerations is the length of microchannels in the structure of a CGG. A CGG with a short length fails to provide the complete diffusive mixing, while the size of the microchip would unfavorably increase by incorporating a long CGG. Considering a CGG as a tree-like structure consisting of T-shaped micromixers, the mixing process of the species at a straight microchannel has been solved analytically. Herein,... 

    Numerical investigations of fluid flow and lateral fluid dispersion in bounded granular beds in a cylindrical coordinates system

    , Article Chemical Engineering and Technology ; Volume 30, Issue 10 , 2007 , Pages 1369-1375 ; 09307516 (ISSN) Soleymani, A ; Turunen, I ; Yousefi, H ; Bastani, D ; Sharif University of Technology
    Results are presented from a numerical study examining the flow of a viscous, incompressible fluid through a random packing of non-overlapping spheres at moderate Reynolds numbers, spanning a wide range of flow conditions for porous media. By using a laminar model including inertial terms and assuming rough walls, numerical solutions of the Navier-Stokes equations in three-dimensional porous packed beds resulted in dimensionless pressure drops in excellent agreement with those reported in a previous study. This observation suggests that no transition to turbulence could occur in the range of the Reynolds number studied. For flows in the Forchheimer regime, numerical results are presented of... 

    Thermodynamic analysis of slip flow forced convection through a microannulus

    , Article Journal of Thermophysics and Heat Transfer ; Volume 24, Issue 4 , Oce-Dec , 2010 , Pages 785-795 ; 08878722 (ISSN) Sadeghi, A ; Asgarshamsi, A ; Saidi, M. H ; Sharif University of Technology
    The present investigation is devoted to the second law of thermodynamics analysis of steady-state hydrodynamically and thermally fully developed laminar gasflow in a microannulus with constant but different wall heat fluxes. Slip velocity and temperature jump boundary conditions are usedtodescribe rarefaction effects. Viscous heating is also included for both the wall cooling and heating cases. Using already available velocity profile, closedform expressions are obtained for the transverse distribution of temperature and entropy generation rates. The results demonstrate that the effectof the wall heatfluxes ratioonentropy generation is negligible atlarge valuesofthe group parameter and... 

    Thermally developing electroosmotic flow of power-law fluids in a parallel plate microchannel

    , Article International Journal of Thermal Sciences ; Volume 61 , 2012 , Pages 106-117 ; 12900729 (ISSN) Sadeghi, A ; Saidi, M.H ; Veisi, H ; Fattahi, M ; Sharif University of Technology
    The present investigation considers the thermally developing electroosmotic flow of power-law fluids through a parallel plate microchannel. Both the viscous dissipation and Joule heating effects are taken into account and a step change in wall temperature is considered to represent physically conceivable thermal entrance conditions. Expressions for the dimensionless temperature and Nusselt number in the form of infinite series are presented. In general, the resultant eigenvalue problem is solved numerically; nevertheless, an analytical solution is presented for the regions close to the entrance. A parametric study reveals that increasing amounts of the Peclet number result in higher wall...