Numerical Simulation of Heat and Mass Transfer of Limestone Decomposition in Normal Shaft Kiln

2011 ◽  
Author(s):  
Duc Hai Do ◽  
Eckehard Specht
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Large Scale ◽  
Solid Material ◽  
Local Heat ◽  
Operational Parameters ◽  
Calcination Process ◽  
One Dimensional ◽  
Shrinking Core ◽  
Particle Bed

A mathematical model of lime calcination process in normal shafts kiln has been developed to determine the heat and mass transfer between the gas and the solid. The model is one-dimensional and steady state. The transport of mass and energy of the gas and the solid is modeled by a system of ordinary differential equations. A shrinking core approach is employed for the mechanics and chemical reactions of the solid material. The model can be used to predict the temperature profiles of the particle bed, the gas phase along the length of kiln axis. The calcination behavior of the particle bed can be also investigated. The influences of operational parameters such as: energy input, the origin of feed limestone and the lime throughput on the kiln performance including pressure drop are considered. Additionally, the local heat loss through the kiln wall is studied. The results of this study are direct utility for optimization and design of large-scale technical shaft kilns.

scholarly journals Nonstationary flow of roiling liquid

1984 ◽  
Vol 6 (4) ◽  
pp. 12-20
Author(s):  
Duong Ngoc Hai
Keyword(s):  
Mass Transfer ◽  
Differential Equations ◽  
Phase Boundary ◽  
Heat And Mass Transfer ◽  
Numerical Results ◽  
Linear Differential Equations ◽  
Nonstationary Flow ◽  
One Dimensional ◽  
Boiling Liquid ◽  
Linear Differential

Steady one-dimensional nonstationary flow of boiling liquid from finite or infinit pipe in a consideration of the effect of the phase-boundary heat and mass transfer. The Received system of quasi-linear differential equations has been decided by the modificati on of Lax - wendroff method in IBM. Numerical results are compared as xperimental data.

A T-RANS/VLES Approach to Indoor Climate Simulations

2002 ◽  
Author(s):  
S. Kenjeresˇ ◽  
K. Hanjalic´ ◽  
S. B. Gunarjo
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Large Scale ◽  
Single Point ◽  
Ventilation System ◽  
Convective Motion ◽  
Wall Friction ◽  
Indoor Climate ◽  
Thermal Buoyancy ◽  
Order Of Magnitude

For accurate prediction of flow, scalar transport and wall heat and mass transfer in complex building space we propose a time-dependent RANS (T-RANS) approach which resolves in time and space the large-scale convective motion and associated deterministic eddy structure. The residual (“subscale”) turbulence is modeled by a single-point closure. The method can be regarded as Very Large Eddy Simulations (VLES) since the deterministic and modeled contribution to the turbulence moments are of the same order of magnitude. The modeled part becomes dominant in the near-wall regions where there are no large eddies and the proper choice of the subscale model is especially important for predicting wall friction and heat transfer. We use an ensemble-averaged 〈k〉 - 〈ε〉 - 〈θ2〉 algebraic stress/flux/concentration closure as the subscale model which can provide information about the stress and heat/species flux anisotropies. The method is especially advantageous for predicting flows driven or affected by thermal buoyancy, for which the conventional eddy-viscosity/diffusivity RANS models and gradient transport hypotheses are known to fail even in simple generic configurations. The approach was validated in a series of buoyancy-driven flows for which experimental, DNS and LES data are available. Examples of full-scale application include computational simulations of real occupied and furnished residential or office space in which the furniture elements and persons are treated as passive blocking elements. The simulation showed that the T-RANS approach can be used as a reliable tool for a variety of applications such as optimization of heating and ventilation system, building space insulation, indoor quality, safety measures related to smoke and fire spreading, as well as for accurate wall heat and mass transfer predictions.

scholarly journals Heat and mass transfer enhancement strategies by impinging jets: A literature review

2020 ◽  
pp. 227-227
Author(s):  
Florin Bode ◽  
Claudiu Patrascu ◽  
Ilinca Nastase
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Large Scale ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Nozzle Geometry ◽  
Small Scale ◽  
Mixing Enhancement ◽  
Transfer Enhancement

Heat and mass transfer can be greatly increased when using impinging jets, regardless the application. The reason behind this is the complex behavior of the impinging jet flow which is leading to the generation of a multitude of flow phenomena, like: large-scale structures, small scale turbulent mixing, large curvature involving strong normal stresses and strong shear, stagnation, separation and re-attachment of the wall boundary layers, increased heat transfer at the impinged plate. All these phenomena listed above have highly unsteady nature and even though a lot of scientific studies have approached this subject, the impinging jet is not fully understood due to the difficulties of carrying out detailed experimental and numerically investigations. Nevertheless, for heat transfer enhancement in impinging jet applications, both passive and active strategies are employed. The effect of nozzle geometry and the impinging surface macrostructure modification are some of the most prominent passive strategies. On the other side, the most used active strategies utilize acoustical and mechanical oscillations in the exit plane of the flow, which in certain situations favors mixing enhancement. This is favored by the intensification of some instabilities and by the onset of large scale vortices with important levels of energy.

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