2-D FEM MODELING OF MICROWAVE HEATING OF COAL PARTICLESEGEE 520 SEMESTER PRESENTATIONbyOjogbane M. AchimuguMay 3rd 2007

•OutlineIntroductionObjectivesGoverning EquationsSolutionValidationParametric studyConclusion

• Introduction

-Typical behavior of Microwave heating in coal particles-Fast, volumetric heating and energy savings,-More efficient than conventional heating-Draw back is temperature measurement and commercialization(Marland S. et. al) -Application of the Finite Elemental Model (FEM) to solve PDE of a 2-D problem

•Objectives

ability to visualize system behavior

ability to predict temperature rise

verify results with respect to previous work done

study basic parameters that influences the behavior of FEM analysis within coal particles

•Governing equationsConstitutive relations

Heat equation VρСΡ∂T/∂T=v( k vT)+P Maxwell’s equation

E= electric field intensity, C = speed of light m/s2 along with frequency respond analysis from the

structural mechanics module to incorporate 2450HzBoundary conditions; For x = 0 -k ∂T/∂x = 0 t> 0

Initial condition T (x, y, 0) TA, dt/dx = 0 at x=0. Where TA = the ambient

temperature.

• Solutions

•Heating profile of coal particles at time 120 second •Cross section of temperature

time profile

Power = 1500W, time = 120s, F=2450Hz, E”=3.44

• Validation

power density =2.89 W/cm2 for slabs & 3.48W/cm2 for cylinder.

Power density = 1.875 W/m2

• Parametric study

•temperature distribution at higher inward heat heat flux = 38750 W/ m2 and frequency = 28GHz, Time = 120s

•thermal conductivity of 200 W/ (m.K), time 120s, power 1500W

• ConclusionCoal grinding and cleaning remains an issue at

lower temperature Selective heating by microwave pretreatment can be

predicted for coal analysis and grinding using FEMThe use of FEM for a 2-D problem thus appears to

be a good approach in studying microwave heating

Parameters needs to be valid to operate in FEM

Though time consuming, but very realistic