Unformatted text preview: assumed perfectly insulated. (1) The emissivity of all surfaces is 0.8. Find the sidewall temperature. (2) If all surfaces are of blackbody, what will be the sidewall temperature? 4. A “focusing” radiation heater is constructed as shown with the hot surface at 1000ºC having an emissivity of 0.55 and a diameter of 0.5 m. The walls surrounding the heater surface are insulated and have the emissivity of 0.4. The depth of the wall is 0.5 m. The arrangement is open to a large room at 20ºC. Calculate the heat transfer to the room. Room at 20ºC 0.5 m in depth D = 0.5 m insulated Heater at 1000ºC 5. A horizontal metal thermocouple with a diameter of 3 mm and an emissivity of 0.6 is inserted in a duct to measure the temperature of an airstream flowing at 7 m/s. The walls of the duct are 400ºC, and the thermocouple indicates a temperature of 100ºC. (1) Calculate the convection heat transfer coefficient. (2) Find the true gas temperature....
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 Spring '11
 nezihtopaloglu
 Heat, Heat Transfer, Emissivity, heattransfer rate, sidewall temperature, true gas temperature

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