The composite wall of an oven consists of three materials, two of which are of known thermal conductivity, kA = 20 W/m?K and kC = 50 W/m?K, and known thickness, LA = 0.30 m and LC = 0.15 m. The third material, B, which is sandwiched between materials A and C, is of known thickness, LB = 0.15m but the thermal conductivity kB is unknown.
Under steady-state operating conditions, measurements reveal an outer surface temperature of Ts,o = 20 °C, an inner surface temperature of Ts,i = 600 °C, and an oven air temperature of T&= 800 °C. The convection coefficient h inside the oven is known to be 25 W/m2?K. What is the value of kB?
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Word document shows how to calculate the value of kB for an oven when given the convection coefficient, surface temperature, etc.
Window Thickness To Maintain Safe Heat Level
A new oven has been designed which has self-cleaning capability. The oven window must be from two transparent high temperature polymers (A and B) with thermal conductivities of K_A=0.15 W/mK and K_B=0.08 W/mK. Thickness of layer Ais twice as much as layer B. During the self-cleaning the oven wall and the air temperature are 400C while the room temperature is 25 C. The inside radiation and convection heat transfer coefficient are 25 W/m^2K, while the outside heat transfer coefficient is 15 W/m^2K. What is the minimum thickness of the window to ensure the temperature at the outer surface of the window is 50 C or less for safety reasons.View Full Posting Details