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Microwave Cooking Modeling

Microwave Cooking Modeling. Heat and moisture transport Andriy Rychahivskyy. Outline. What is a microwave? Nature of microwave heating Goals of the project Model description Results Conclusions and recommendations. Scheme of a microwave oven. What is a microwave?. . H. . .

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Microwave Cooking Modeling

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  1. Microwave Cooking Modeling Heat and moisture transport Andriy Rychahivskyy

  2. Outline • What is a microwave? • Nature of microwave heating • Goals of the project • Model description • Results • Conclusions and recommendations

  3. Scheme of a microwave oven

  4. What is a microwave?  H   ─electric field H ─magnetic field  ─ wavelength (12.2 cm for 2.45 GHz)

  5. +  + Microwave cooking principle • Microwaves act on 1) salt ions to accelerate them; 2) water molecules to rapidly change their polar direction

  6. Microwave cooking principle • Microwaves act on 1) salt ions to accelerate them; 2) water molecules to rapidly change their polar direction • Food’s water content heats the food due to molecular “friction”

  7. Goal of the project • Design a model of microwave cooking predicting temperature andmoisture distributionwithin the food product

  8. Phenomena to model • Electromagnetic wave distribution • Heat transport within the product • Mass (water and vapor) transport

  9. Governing equations and laws • Maxwell’s equations • Energy balance equation • Water and vapor balance equations • Ideal gas law • Darcy’s law for a flow in a porous medium

  10. solid particle • water • vapor Porous medium

  11. solid particle • water • vapor Porous medium

  12. Geometrical model • top • C ­MW cavity • M­food product • G­waveguide • bottom

  13. Heat source • electromagnetic properties:ε, σ(control how a material heats up) ε = ε* + i ε** • radial frequency:ω = 2p*2.45 GHz

  14. Heat source Electric field intensity

  15. Heat source Electric field intensity

  16. Heat source Electric field intensity Heat source

  17. Convection-diffusion equation • heat capacity:(how much heat the food holds) • thermal conductivity: • (how fast heat moves) • latent heat: • (absorbed due to evaporation) • interface mass transfer rate:

  18. Boundary and initial conditions • thermal conductivity: • (how fast heat moves) • heat transfer coef.: • (thermal resistance) • latent heat: • (absorbed due to evaporation)

  19. One-dimensional model with at at

  20. Numerical results /without mass transport/

  21. Numerical results /without mass transport/

  22. Numerical results /general 1D model/

  23. Interpretation of results

  24. Conclusions • Electromagnetic source is constant • Heating-up of the product until 100oC develops linear in time • T at the boundary >> T in the kernel • Moisture loss occurs only in a boundary layer

  25. Recommendations • Validate the results • Extend our implementation • Perform a parameter study

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