1. 2-D FEM MODELING OF MICROWAVE HEATING OF COAL PARTICLES EGEE 520 SEMESTER PRESENTATION by Ojogbane M. Achimugu May 3 rd 2007

2. Outline Introduction Objectives Governing Equations Solution Validation Parametric study Conclusion

3. 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

4. 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

5. Governing equations Constitutive relations Heat equation VρС Ρ ∂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 2450Hz Boundary conditions; For x = 0 -k ∂T/∂x = 0 t> 0 Initial condition T (x, y, 0) T A, dt/dx = 0 at x=0. Where T A = the ambient temperature.

6. 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

7. Validation power density =2.89 W/cm2 for slabs & 3.48W/cm2 for cylinder. Power density = 1.875 W/m2

8. 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

9. Conclusion Coal grinding and cleaning remains an issue at lower temperature Selective heating by microwave pretreatment can be predicted for coal analysis and grinding using FEM The 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