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Modeling Microwave Cooking: Heat and Moisture Transport in Food

This project explores the nature of microwave heating, goals, model description, results, conclusions, and recommendations for predicting temperature and moisture distribution in food during microwave cooking. It covers phenomena to model, governing equations, geometrical model, heat source, equations, and numerical results with and without mass transport for better understanding. Findings suggest a linear heating pattern, with moisture loss mainly at the boundary layer. Future recommendations include result validation and further implementation for a comprehensive study.

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Modeling Microwave Cooking: Heat and Moisture Transport in Food

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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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