Numerical Modeling of Co-Firing Chunk Coal and Oat Hulls in a Stoker Boiler

2011 ◽  
Author(s):  
Xinhui Zhang ◽  
Mohsen Ghamari ◽  
Albert Ratner
Keyword(s):  
Coal Combustion ◽  
Good Accuracy ◽  
Numerical Study ◽  
Three Dimensional ◽  
Combustion Model ◽  
Transfer Model ◽  
Light Weight ◽  
Economic Potential ◽  
Oat Hulls ◽  
Real Size

The current study presents a numerical study of co-firing chunk coal and one kind of light weight biomass, oat hulls, in a stoker boiler. First, a standard combustion model was applied to simulate coal combustion in a real size three dimensional boiler; the results were compared with the temperatures measured at different locations of the stoker boiler to assess the accuracy of heat sink and heat transfer model. Once a good accuracy was achieved, a devolatilization model for oat hulls was derived from experimental data and was matched with this combustion model to simulate combustion in a co-firing stoker boiler. The results showed that light biomass burns in suspension, similar to pulverized coal by following the air flow. Also, the peak temperature inside the furnace inversely varies with the increase of co-firing percentage of oat hulls. This numerical study reveals thermal and economic potential of using unprocessed light weight biomass on the existing combustion facility.

Numerical Study on 3D Coupled Heat Transfer of Thrust Chamber with Regenerative Cooling

2011 ◽  
Vol 52-54 ◽  
pp. 1057-1061
Author(s):  
Tao Nie ◽  
Wei Qiang Liu
Keyword(s):  
Heat Transfer ◽  
Optimization Design ◽  
Numerical Study ◽  
Computing Time ◽  
Three Dimensional ◽  
Geometrical Model ◽  
Performance Estimation ◽  
Transfer Model ◽  
Empirical Formulas ◽  
Coupled Heat Transfer

To obtain temperature distribution in regenerative-cooled liquid propellant rocket nozzle quickly and accurately, three-dimensional numerical simulation employed using empirical formulas. A reduced one-dimensional model is employed for the coolant flow and heat transfer, while three dimensional heat transfer model is used to calculate the coupling heat transfer through the wall. The geometrical model is subscale hot-firing chamber. The numerical results agree well with experimental data, while temperature field in nozzle obtained. In terms of computing time and accuracy of results, this method can provide a reference for optimization design and performance estimation.

A Numerical Study of the Thermal Performance of a Tape Ball Grid Array (TBGA) Package

1999 ◽  
Vol 122 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Sanjeev B. Sathe ◽  
Bahgat G. Sammakia
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Numerical Study ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Cover Plate ◽  
Transfer Model ◽  
Turbulence Regime ◽  
Chip Carrier ◽  
Internal Thermal Resistance

This paper deals with the thermal management of a TBGA chip carrier package. In TBGA packages the backside of the chip is available for heat sink or heat spreader (cover plate) attach. By attaching a heat sink directly to the chip and using a thin layer of high thermal conductivity adhesive, a very low internal thermal resistance can be achieved. The package is attached to an organic card and placed vertically in a channel. A three-dimensional conjugate heat transfer model is used, accounting for conduction and radiation in the package and card and convection in the surrounding air. A simplified turbulence model is developed to predict temperatures in the low Re turbulence regime. A parametric study is performed to evaluate the effects of card design, air velocities, interconnect thermal conductivities and thermal radiation on the chip junction temperatures. An experimental study was also conducted to verify the model. Even though the geometry is highly complex due to the multilayer construction of the module and the card, agreement between the model and the experimental measurement is excellent. It was shown that radiation heat transfer can be an equally significant mode as convection in the natural convection regime. [S1043-7398(00)01302-5]

Numerical Study on Coupled Heat Transfer of Thrust Chamber with Raised Structure

2012 ◽  
Vol 516-517 ◽  
pp. 107-110
Author(s):  
Tao Nie ◽  
Wei Qiang Liu
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Axial Direction ◽  
Heat Transfer Model ◽  
Chamber Wall ◽  
Transfer Model ◽  
Thrust Chamber ◽  
Coupled Heat Transfer ◽  
Flow And Heat Transfer

By the use of the map of the thermal resistance among volume cells, we establish a coupled heat transfer model of the hot gas, chamber wall and coolant. A reduced one-dimensional model was employed for the coolant flow and heat transfer, and three dimensional heat transfer model was used to calculate the coupling heat transfer through the wall, considering heat transfer at circumferential direction, axial direction and radial direction. Based on the study the mechanism of the cooling structure heat transfer, the computing model was employed and achieved the rule of heat flux and temperature of gas wall. Simultaneously, influence of different cooling structure was performed. The results indicated that the cooling structure with raised structure could better reduce the temperature of the chamber wall.

scholarly journals NUMERICAL STUDY OF DYNAMICS INTRACHAMBER PROCESSES IN SOLID PROPELLANT SUSTAINER TAKING INTO ACCOUNT FLIGHT OVERLOADS. PART 1. CALCULATION METHOD

2021 ◽  
pp. 91-103
Author(s):  
Mikhail Egorov ◽  
◽  
Dmitry Egorov ◽  
Sergey Egorov ◽  
◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Condensed Phase ◽  
Solid Propellant ◽  
Solution Method ◽  
Numerical Study ◽  
Three Dimensional ◽  
Combustion Model ◽  
Cruise Missile ◽  
Time Step ◽  
Nozzle Block

The dynamics of transient in-chamber processes (internal ballistics) of the cruise missile's second-stage cruise missile propulsion system is studied, taking into account, in the general case, distributed spatially-three-dimensional and time-varying flight overloads. The research method is the formulation of a computational experiment. Be considered coupled formulation of the problem, including: – transient triggering of igniter device (the rate of combustion of the igniting composition is described on the basis of experimental and theoretical approach afterburn combustion products in case igniting device); preheating, ignition and subsequent unsteady and turbulent combustion of solid propellant charge (used quasi-homogeneous combustion model based on the equations of heat conduction and chemical kinetics recorded for a condensed phase (solid fuel), taking into account the influence of the gas phase (torch) on the process of combustion in the condensed phase; the method of solving the problem – finite difference method); – non-stationary three-dimensional homogeneous-heterogeneous four phase flow of air and products of combustion in the combustion chamber, the nozzle block and the block launchers rocket engine (used approaches of continuum mechanics of multiphase media; the basic system of equations system of vortex differential equations of gas dynamics solution method – a multi-parameter class of difference schemes of splitting into physical processes of the method Davydova); – depressurization of the combustion chamber of the SRB (equation of motion of the plug nozzle block – Newton's second law; the proposed solution method – Euler's method). Each of the subtasks is considered in a relationship and resolved simultaneously – at one time step. To solve the formulated problem, a set of application programs has been developed using (for the main calculation module) the OpenCL multithreaded information processing standard. The performance of the software product was checked.

Mixing and Combustion Characteristics of a Side Dump Combustor With Noncircular Fuel Injectors

1994 ◽  
Author(s):  
T. M. Liou ◽  
L. Chen
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Reacting Flows ◽  
Combustion Characteristics ◽  
Combustion Model ◽  
Mean Velocity ◽  
Dump Combustor ◽  
Aspect Ratios ◽  
Switching Phenomenon ◽  
Axis Switching

A numerical study of the mixing and combustion characteristics of an axial jet issued from rectangular injectors of different aspect ratios (3 and 1/3) in a three-dimensional side-dump combustor is presented. The Reynolds number based on the bulk mean velocity and combustor duct height was 5.9×104 and the momentum ratio of the axial-fuel jet to the side-air jets was 0.2. A two equation k-ε turbulence model incorporating with a two-step finite-rate combustion model was adopted to simulate the nonreacting and reacting flows in a side-dump combustor. The computed nonreacting flow pattern was verified by the available experimental data. A comparison between the reacting and nonreacting flow patterns was made. The axis switching phenomenon previously observed for the unconfined or confined noncircular jets was examined in detail for the present side-dump combustor. It was found that the axis switching phenomenon was incomplete and that the aspect ratio had weak effects on the turbulent mixing and combustion in the ducted rocket combustor under the investigated conditions.

EXPERIMENTAL AND NUMERICAL STUDY OF THREE-DIMENSIONAL NATURAL CONVECTION AND FREEZING IN WATER

1994 ◽  
Author(s):  
C. Abegg ◽  
Graham de Vahl Davis ◽  
W.J. Hiller ◽  
St. Koch ◽  
Tomasz A. Kowalewski ◽  
...  
Keyword(s):  
Natural Convection ◽  
Numerical Study ◽  
Three Dimensional
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