# PS_10 - heat transfer coefficient for natural convection is...

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ChBE421 Problem Set # 10 Fall 2009 1. The heating element in a 1000 watt radiant heater consists of a cylindrical filament 1 mm in diameter with a total length of 1 meter. Emissivity of filament: ε = 0.65. Convective heat transfer coefficient: h = 42 W/m 2 K. Stefan-Boltzman constant σ = 5.676 × 10 –8 W/m 2 K 4 . Find the surface temperature of the filament if the surroundings are at 20 °C. 2. A small wood-burning fireplace made of cast iron ( ε = 0.45) has dimensions 1.8 ft × 1.5 ft × 2.25 ft. The fire generates heat at a rate of 3750 Btu/hr. The room temperature is 68 °F and the
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Unformatted text preview: heat transfer coefficient for natural convection is 0.8 Btu/hr ft 2 F. Find the surface temperature of the stove. 3. A bare horizontal pipe ( = 0.66) 10 m long with 15 cm OD has an outer surface temperature of 115 C. The pipe is located indoors in a room with temperature 24 C. Find the total rate of heat loss due to radiation. Find the radiative heat transfer coefficient (h r )....
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## This note was uploaded on 03/18/2010 for the course CHBE 421 taught by Professor 1` during the Spring '10 term at University of Illinois, Urbana Champaign.

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