Numerical Simulation and Optimization of the Thermodynamic Process of the Molten Salt Furnace

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Lian Ning ◽  
Dong Fu ◽  
Chenn Q. Zhou ◽  
Jiemin Zhou
Keyword(s):  
Numerical Model ◽  
Molten Salt ◽  
Gas Flow ◽  
Radiation Heat Transfer ◽  
Furnace Chamber ◽  
Flow Temperature ◽  
Furnace Process ◽  
Simulation And Optimization ◽  
Computational Fluid Dynamics Cfd ◽  
Vane Angle

In this paper, a numerical model of the molten salt furnace process was developed, by using computational fluid dynamics (CFD) technique and considering the gas flow, the combustion and the radiation heat transfer. The results demonstrate that the performances of the salt furnace could be improved by optimization using the numerical model. The temperatures along the circumference of the furnace coil and outside shell are quite even, and the deviant combustion phenomenon is not observed. A back-flow formed in the upper part of the furnace chamber enhances the circulation and the mixing of the gas and effectively stabilizes the combustion in the furnace. The behaviors of CO, CO2, NOx, and H2O are presented in terms of the gas flow, temperature distribution and volumetric concentration distribution. It is concluded that the furnace with the constant air flow rate of 15,500 Nm3/h and the guiding vane angle at 48–50 deg is optimized for the combustion effectiveness.

Numerical Simulation of the Thermodynamic Process of the Molten Salt Furnace

2012 ◽  
Author(s):  
Lian Ning ◽  
Chenn Q. Zhou ◽  
Jiemin Zhou
Keyword(s):  
Molten Salt ◽  
Gas Flow ◽  
Radiative Heat ◽  
Guide Vane ◽  
Furnace Chamber ◽  
Air Flow Rate ◽  
Thermodynamic Process ◽  
Volumetric Concentration ◽  
Flow Temperature ◽  
Simulation Results

In this paper, a numerical model of the thermodynamic process was developed, by using CFD (software) technique and considering the gas flow, the diffused combustion and the radiative heat transfer in the molten salt furnace. This model aims to optimize the operating parameters. Simulation results demonstrate that the performances of the salt furnace can be improved by optimization. The temperatures along the fire wall circumference are quite even, and the deviant combustion phenomenon is not observed. A back-flow formed in the upper part of the furnace chamber enhances the circulation and the mixing of the gas, helping to effectively stabilize the combustion in the furnace. The behaviors of CO, CO2, NOx and H2O are presented in terms of the gas flow, temperature distribution and volumetric concentration distribution. The furnace with the constant air flow rate of 15500Nm3/h and the angle of guide vane at 48∼50 ° can increase the combustion effectiveness.

scholarly journals Thermochemical Heat Storage in a Lab-Scale Indirectly Operated CaO/Ca(OH)2 Reactor—Numerical Modeling and Model Validation through Inverse Parameter Estimation

2021 ◽  
Vol 11 (2) ◽  
pp. 682
Author(s):  
Gabriele Seitz ◽  
Farid Mohammadi ◽  
Holger Class
Keyword(s):  
Numerical Model ◽  
Gas Flow ◽  
Reaction Rate ◽  
Heat Storage ◽  
Bulk Material ◽  
Fixed Bed ◽  
Experimental Results ◽  
Fixed Bed Reactor ◽  
Thermochemical Heat Storage ◽  
Speed Up

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

scholarly journals Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

2021 ◽  
Vol 11 (7) ◽  
pp. 2961
Author(s):  
Nikola Čajová Kantová ◽  
Alexander Čaja ◽  
Marek Patsch ◽  
Michal Holubčík ◽  
Peter Ďurčanský
Keyword(s):  
Particulate Matter ◽  
Flue Gas ◽  
Gas Flow ◽  
Negative Impact ◽  
Combustion Process ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Imaging ◽  
Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

scholarly journals Numerical Calculations of WR-40 Boiler Based on its Zero-Dimensional Model

2014 ◽  
Vol 35 (2) ◽  
pp. 173-180 ◽  
Author(s):  
Bartłomiej Hernik
Keyword(s):  
Numerical Model ◽  
Flue Gases ◽  
Balance Model ◽  
Furnace Chamber ◽  
Gas Temperature ◽  
Cfd Modelling ◽  
Boiler Furnace ◽  
Average Temperature ◽  
Furnace Outlet ◽  
Dissipation Model

Abstract Generally, the temperature of flue gases at the furnace outlet is not measured. Therefore, a special computation procedure is needed to determine it. This paper presents a method for coordination of the numerical model of a pulverised fuel boiler furnace chamber with the measuring data in a situation when CFD calculations are made in regard to the furnace only. This paper recommends the use of the classical 0-dimensional balance model of a boiler, based on the use of measuring data. The average temperature of flue gases at the furnace outlet tk" obtained using the model may be considered as highly reliable. The numerical model has to show the same value of tk" . This paper presents calculations for WR-40 boiler. The CFD model was matched to the 0-dimensional tk" value by means of a selection of the furnace wall emissivity. As a result of CFD modelling, the flue gas temperature and the concentration of CO, CO2, O2 and NOx were obtained at the furnace chamber outlet. The results of numerical modelling of boiler combustion based on volumetric reactions and using the Finite-Rate/Eddy-Dissipation Model are presented.

Combined Effects of Overheating and Soot-Blower Erosion on Reheater Tubing in a Gas-Fired Large Capacity Boiler

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Nasr M. Hosny
Keyword(s):  
Data Analysis ◽  
Oxide Layer ◽  
Test Data ◽  
Gas Flow ◽  
Combined Effects ◽  
Unit Operation ◽  
Metal Oxidation ◽  
Flow Temperature ◽  
Large Capacity ◽  
Short Time

In a large capacity tangentially fired boiler, the final reheater tubing sustained abnormal oxidation and localized excessive metal wastage in a short time of the unit operation. The root causes of the problem are identified by test data analysis. The test data indicated that the reheater tubing metal temperatures in the affected areas exceeded the recommended limit of the metal oxidation temperature due to higher than expected local gas temperatures and velocities. A soot-blower facing the overheated portion of the reheater leading tubes accelerated the process of metal wastage by periodically removing the oxide layer. The configuration of the boiler internals upstream of the reheater section is found to be the main cause of the localized overheating. Side-to-side gas flow/temperature stratification due to tangential firing contributed to a lesser degree to the problem. The results and conclusions presented in this paper should be a beneficial guide to the designer of large capacity boilers.

Numerical Simulation of Insulin Depot Formation and Absorption in Subcutaneous Tissue Modeled as a Homogeneous Anisotropic Porous Media

2021 ◽  
Author(s):  
Michael Zedelmair ◽  
Abhijit Mukherjee
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Insulin Pump ◽  
Subcutaneous Tissue ◽  
Saturated Porous Media ◽  
Anisotropic Porous Media ◽  
Effective Option ◽  
Computational Fluid Dynamics Cfd ◽  
Experimental Findings ◽  
Subcutaneous Adipose

Abstract In this study, a numerical model of the insulin depot formation and absorption in the subcutaneous adipose tissue is developed using the commercial Computational Fluid Dynamics (CFD) software. A better understanding of these mechanisms can be helpful in the development of new devices and cannula geometries as well as predicting the concentration of insulin in the blood. The injection method considered in this simulation is by the use of an insulin pump using a rapid acting U100 insulin analogue. The depot formation is analyzed running Bolus injections ranging from 5-15 units of insulin corresponding to 50-150µl. The insulin is injected into the subcutaneous tissue in the abdominal region. The tissue is modeled as a fluid saturated porous media. An anisotropic approach to define the tissue permeability is studied by varying the value of the porosity in parallel and perpendicular direction having an impact on the viscous resistance to the flow. Following recent experimental findings this configuration results in a disk shaped insulin depot. To be able to run the simulation over longer timeframes the depot formation model has been extended implementing the process of absorption of insulin from the depot. The developed model is then used to analyze the formation of the insulin depot in the tissue when using different flow rates and cannula geometries. The numerical model is an effective option to evaluate new cannula designs prior to the manufacturing and testing of prototypes, which are rather time consuming and expensive.

Block Treatment of Multi-Layer Wafers for the Development of a Numerical Model of a 300mm Batch Heat Treatment Furnace

2006 ◽  
Vol 15-17 ◽  
pp. 537-542
Author(s):  
Eun Yi Ko ◽  
Kyung Woo Yi
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Thermal Treatment ◽  
Radiation Heat Transfer ◽  
Great Influence ◽  
Vertical Direction ◽  
Treatment Furnace ◽  
Numerical Experimentation ◽  
Modeling Strategy

Of all the processing stages for wafers, interior temperature distribution in thermal treatment furnaces has a great influence on wafer properties. Therefore, internal temperature distribution is a key factor for operating a furnace. However, it is practically impossible to directly measure temperatures within the furnace, and consequently the need for a reliable numerical model to analyze temperature distribution is becoming increasingly urgent. Exact modeling of the processing is very difficult because the structure of the furnace used for thermal treatment is very complex, with large numbers of Si wafers stacked within. Therefore, simplified modeling is necessary. The modeling strategy of the present study is to reduce the radiation calculation domain and simplify the model by replacing the wafer stack region with a single block. It is necessary to determine the vertical and horizontal effective thermal conductivities of the block to reflect radiation heat transfer between wafers. In this study, calculations were performed through numerical experimentation, using r k as the heat transfer coefficient in the direction of the radius, and v k for the vertical direction. Using these calculated property values, the temperature distribution within a 300mm thermal treatment furnace can be obtained.

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