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The list of thermal examples and download links can be found on page   QuickField : thermal examples

Note : Red : The example use a special function. Blue : Question. Green : To an internal link. Orange : To an external link.


 

Heat exchange between surfaces.  (non-linear problem)


The heating energy of a cylindrical furnace is provided by an electrical resistance near the inner wall. The inside diameter is 75 mm and the length 150 mm. The oven is open at one end at 27°C. The electrical power is 1840 W and :

•  The inner surfaces behave like blackbodies.
•  Heat exchanges by convection are negligible.
•  The furnace has a low thermal conductivity (0.1 W / mK) and
    there is no exchange with the outside.
•  The thermal conductivity of air is temperature dependant
  •   What are the temperatures of the inner surfaces ?
  •   Use the "view factor" for two coaxial and parallel disc - see example_d4_pro.txt
  •   Answer : T1 = 1500 K and T2 = 1650 K using the average surface temperature integral calculator.

Heat exchange between surfaces

 

Internal temperature of a furnace


The wall of an industrial furnace is made of a wall which thickness is 0.15 m and thermal conductivity is 1.2 W / mK.

•  The external surface emissivity is 0.8
•  At steady state, the external temperature is 100°C.
•  The convection transfer coefficient is 20 W/(m².K)
•  T(surroundings)=T(air)=25°C.
  •   What is the internal temperature of the furnace ?
  •   The thermal power of the inner wall is the sum of the convective and radiative heat - see example_d5.txt
  •   Answer : 625.5 K

Furnace wall temperature

 

Self cleaning oven   ( + LabelMover - Optimization)


A self cleaning oven design involves the use of a composite window. The composite is to consist of two high temperature A and B.

•  For plastic A, the thermal conductivity is λA = 0.15 W / mK.
•  For plastic B, the thermal conductivity is λB = 0.08 W / mK.
•  The oven wall temperature is 400°C.
•  The room temperature is T∞ = 25°C.
•  Inside convection and radiation transfer coefficients are 25 W/(m².K)
•  Outside convection transfer coefficient is 25 W/(m².K)
  •   What is the thickness of plastic A so that the temperature on the window is ≤ 50°C ?
  •   The thermal power of the inner surface is the sum of the convective and radiative heat.
  •   We can use LabelMover to guess the answer, (Optimization function) .
  •   Answer : 3.6 cm

temperature of a composite window


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