Sous Vide● Modernist cooking technique ● Uses water bath at exact temperatures ● Usually done with immersion circulator
and vacuum sealer ● Precise repeatable results ● Can create formerly impossible flavors
and textures
Materials ● 1 beet● 1 zuchinni● 2 hot plates● 1 stir bar● 1 HOBO● 3 TMC6-HC
temp sensor● 1 tank● 1 temp
controller
Energy Balance Procedure1. System/Control Volume Boundary: Beet
or Zucchini2. Direction of Heat Transfer: Radial3. Approximate Geometry: Sphere or Cylinder4. Energy Flows & Modes of Heat Transfer:
a. no mass flowb. convection at surfacec. Conduction
5. Boundary Conditions: a. Convection at surfaceb. Symmetrical temp profile
6. Reactions Occurring: none
T∞
T∞
T∞
Beet
Zucchini
Energy Balance Procedure7. Constant k?: Yes
8. Steady State?: No, transient
9. Heat Diffusion Equation:
a) Cylinder: b) Sphere:
10. Solving Approach: Heisler
T∞
T∞
T∞
Beet
Zucchini
Analytical Solution- Heisler● Fo = αt/r2
○ α=thermal diffusivity○ t=time○ r=radius
● θ=(T0-T∞)/(Ti-T∞)○ T0=final temperature at center of object○ T∞=temperature of fluid ○ Ti= initial temperature of object
● Bi=(hr/k)○ h= convection coefficient○ r=radius○ k=thermal conductivity
Knowns- Fo, θ:
● T∞, Ti, T0, α, t, r, k
Unknowns- Bi, h
Results:
● Zucchini: h=24.71 W/mK● Beet: h=59.41 W/mK
Numerical Solution- COMSOLZucchini:
Experimental T0 : 42.94 °C
Theoretical T0 : 42.79 °C
Experimental T0 : 42.94 °C
Theoretical T0 : 38.74 °C
Beet:
-Factors affecting convection coefficient (h):● Surface geometry● Fluid properties (conductivity, viscosity, density)● Fluid velocity-Only surface geometry varied in this experiment● Convection coefficient for beet, 59.41 W/mK, (sphere)
was greater than that of the zucchini, 24.71 W/mK, (cylinder)
● Beet heated at faster rate initially than the zucchini
References1. Ramaswamy, H. S., G. B. Awuah, and S. D. Ali. "Thermophysical Properties of Selected Vegetables as Influenced by
Temperature and Moisture Content." Journal of Food Process Engıneerıng 25.5 (2007): 417-33. Web. 17 Apr. 2016.
2. Tabil, Lope G., Marshall V. Eliason, and Hong Qi. "Thermal Properties of Sugar Beet Roots." Journal of Sugar Beet Research
40.4 (2003): 221-25. Web. 17 Apr. 2016.
3. "What Is Sous Vide." ChefSteps. N.p., n.d. Web. 17 Apr. 2016.<https://www.chefsteps.com/activities/what-is-sous-vide>.
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