Multiphysics Modeling of Microwave Heating of Food Undergoing Heat, Mass and Momentum Transport

Transcription

1 Multiphysics Modeling of Microwave Heating of Food Undergoing Heat, Mass and Momentum Transport J. Chen 1, K. Pitchai 1, S. Birla 2, R. Gonzalez 2, D. Jones 1, J. Subbiah 1 1 University of Nebraska Lincoln 2 ConAgra Foods, Inc ASABE International Meeting July 23, Kansas City, Missouri Session 223: Food and Bioproducts Modeling

2 Microwaveable foods - convenient Growing Billion dollar industry 2

3 Domestic ovens non-uniform heating Standing wave pattern Temperature dependent properties 3

4 Food quality and safety issues Vision, Taste, Smell, Nutrition Outbreaks 4

5 Microwave model can be used for Food product design Designing food products that respond well to microwave cooking is a mixture of art and science, with heavy emphasis on the science. 5 Kate Bertrand. Microwavable Foods Satisfy Need for Speed and Palatability. Food Technology. 2005, 29(1):30-34.

6 Microwave heating process Microwave heating Liquid pumping Internal heating Internal water vaporization Food sample Vapor convection Multiphysics Electromagnetic heating Heat transfer Mass transfer Momentum transfer 6

7 Objectives Develop a multiphysics model coupling physics of electromagnetic heating, heat, mass, and momentum transfer to simulate microwave heating process. Validate the model using a 19 oz. tray of frozen mashed potatoes on a rotating turntable for 6 min microwave heating. 7

8 Geometric model 1200 W rated power microwave oven. All features of microwave oven included in the model. Magnetron Cavity Waveguide Bump Food Crevice Turntable 8

9 Model physics Electromagnetic Maxwell s equations μ r 1 E 2πf c 2 ε r iε E = 0 Energy Conservation Q m = 2πfε 0 ε E 2 t i=s,w,v ρ i C p,i T + = k eff T λ I + Q m i=w,v ρ i C p,i u i,eff T 9

10 Model physics Mass Conservation c i t + D i c i + u c i = I Momentum Conservation u i = k in,i k r,i μ i p Phase Change of Vaporization I = KM v (p v,eq p v )/(RT) 10

11 Meshing scheme 11 Free tetrahedral elements

12 Partial coupling Calculate EM field distribution Calculate Heat, mass and momentum transfer 12

13 COMSOL-MATLAB interface Developed a custom built MATLAB algorithm to rotate the food at different discrete positions and communicating with COMSOL Multiphysics. Calculate EM field for one location Update material properties Rotate food product to next location Average EM fields of 12 locations Calculate heat, mass, and momentum transfer for one rotation time 13

14 Model assumptions Frequency 2.45 GHz Constant ambient air temperature 20 No bound water in the food domain Air in the food domain was ignored Dielectric properties did not change in one rotation step 14

15 Experimental validation Thermal camera Fiber-optic sensors Total moisture loss ,3 4 5,6 3 Locations of fiber-optic sensors 15

16 Surface temperature profile 2 min-frozen Mashed Potatoes- Rotation C Rep 1 Rep 2 C Experiment Simulation 16

17 Surface temperature profile 4 min-frozen Mashed Potatoes- Rotation Rep 1 C Rep 2 Rep 3 Simulation C 17 Experiment

18 Surface temperature profile 6 min-frozen Mashed Potatoes- Rotation Rep 1 C Rep 2 Rep 3 C Simulation Experiment 18

19 Temperature, C Temperature, C Transient point temperature Experiment Simulation Time, min Experiment Simulation Time, min

20 Temperature, C Temperature, C Transient point temperature Experiment Simulation Experiment Simulation Time, min Time, min

21 Temperature, C Temperature, C Transient point temperature Experiment Simulation Time, min Experiment Simulation Time, min

22 Total Moisture Loss, g Total moisture loss Simulation Experiment Time, min 22

23 Surface temperature & Moisture content Animation Surface temperature, C 23 Normalized surface moisture content, % of initial MC

24 Conclusions A comprehensive 3-D multiphysics model coupling electromagnetic heating, heat, mass, and momentum transfer was developed. Simulation of microwave heating of rotating object was performed using MATLAB - COMSOL interface. Simulated and experimental results are in good agreement. 24

25 Acknowledgements ConAgra Foods, Inc., Omaha. USDA CSREES NIFSI grant (Project number: ) 25

26 Thank you very much for your attention! 26