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Unformatted text preview: ChBE421 Problem Set #7 Fall 2009 1. Nitrogen at 50 C flows through a packed bed of particles at a rate of 200 kg/hr. The bed is 13 cm in diameter, 36 cm high and has porosity 0.48. The particles have specific surface 8.1 cm 1 . Find the pressure drop 2. A cross section of a typical home ceiling is depicted below. T outside = -12 o C h o = 23 W/m 2 K k fiberglass = 0.036 W/m 2 K k wood = 0.17 W/m 2 K T inside = 22 o C h i = 8 W/m 2 K k plaster = 0.824 W/m 2 K a) Given the properties listed for the materials making up the ceiling, determine how much heat is transferred through the insulation and through the studs. b) Determine the change in heat transfer if the ceiling was instead designed for R-38 insulation, hence making the insulation and studs (12 thick). 3. A 3-in. (OD) stainless-steel tube has 16 longitudinal fins spaced around its outside surface as shown. The fins are 3/16 thick and extend 1.75 from the outside surface of the tube (see fig.). shown....
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