# hw 9 - Answer: (a) =0.8 =0.713 (b) qnet,in= 233 KW/m2 and...

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Assignment #9 Due Date: May 2nd, 2010 (Monday before start of class (1:25 pm)). P1. 12.53(a),(b) and (c) FIND: (a) Total, hemispherical emissivity of the surface when maintained at 1000 K, (b) Total, hemispherical absorptivity when irradiated by large surroundings of emissivity 0.8 and temperature 1500 K, (c) Radiosity when maintained at 1000 K and irradiated as prescribed in part (b), Answer: (a) =0.669   =0.745, J=111,128 W/m2 P2. 12.104(a) and (b) FIND: (a) Emissivity and absorptivity of the workpiece at 25°C when it is placed in the furnace, and (b) Net heat rate per unit area into the workpiece for this initial condition and change in temperature with time, dT/dt, for the workpiece at t=0

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Unformatted text preview: Answer: (a) =0.8 =0.713 (b) qnet,in= 233 KW/m2 and dT/dt=9.75K/s at t=0 P3. 12.119 (a) (b) and (c) FIND: (a) Preferred roof coating, (b) Roof surface temperature, (c) Heat load through roof ASSUMPTIONS: (1) Turbulent boundary layer development over entire roof, (2) Constant properties, 3) Negligible atmospheric (sky) irradiation, (4) Negligible contact resistance. Answer (a) zinc oxide white (Table A.12) (b) Ts,o=295 (c) q= 704 W P4: 12.125 FIND: Temperature of top surface of wing for (a) ground and (b) in-flight conditions. Answers (a) Ts= 77.6C (b) Ts= - 35.3C P5. 12.128 FIND: Equilibrium temperature of the radiator. T= 439K...
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## This note was uploaded on 05/18/2011 for the course MEEG 342 taught by Professor Staff during the Spring '08 term at University of Delaware.

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hw 9 - Answer: (a) =0.8 =0.713 (b) qnet,in= 233 KW/m2 and...

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