1. A slab 2L thick, initially at a uniform To, has its surfaces suddenly lowered to...

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1. A slab 2L thick, initially at a uniform To, has its surfaces suddenly lowered to temperature Ts. Simultaneously a volumetric heat source Q" is activated within the slab. Show how you would analyze this problem to determine the temperature response. (Hint: Try a superposition of a steady and a transient problem.) 2. A 5mm-thick steel firewall is suddenly exposed to a radiant heat source that can be approximated as a blackbody at 1000 K. How long will it take for the surface to reach 500 K if the initial temperature of the wall is 300 K? 3. A 3cm-diameter rod of a composite material is initially at 30°C. It is immersed into a chamber in which saturated steam at 120°C condenses on the rod and heats it. When the centerline temperature reaches 110°C, the rod is removed and allowed to cool in 20°C air until the center falls to 30°C. How long does each stage take? Assume a very large heat transfer coefficient for the heating process, and a value of 15 W/m² K for the cooling process. Properties of the composite include p = 1500 kg/m², c = 1800 J/kg K, k = 1.2 W/m K. 1. A slab 2L thick, initially at a uniform To, has its surfaces suddenly lowered to temperature Ts. Simultaneously a volumetric heat source Q" is activated within the slab. Show how you would analyze this problem to determine the temperature response. (Hint: Try a superposition of a steady and a transient problem.) 2. A 5mm-thick steel firewall is suddenly exposed to a radiant heat source that can be approximated as a blackbody at 1000 K. How long will it take for the surface to reach 500 K if the initial temperature of the wall is 300 K? 3. A 3cm-diameter rod of a composite material is initially at 30°C. It is immersed into a chamber in which saturated steam at 120°C condenses on the rod and heats it. When the centerline temperature reaches 110°C, the rod is removed and allowed to cool in 20°C air until the center falls to 30°C. How long does each stage take? Assume a very large heat transfer coefficient for the heating process, and a value of 15 W/m² K for the cooling process. Properties of the composite include p = 1500 kg/m², c = 1800 J/kg K, k = 1.2 W/m K.

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We can use a superposition of a steady and a transient problem to investigate this issue if the slab is constructed of a material with thermal conduct... View the full answer