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Posted: **Sun May 15, 2022 11:00 pm**

: A Disc Of A Diameter D 120 Mm And Thickness Of 1 Mm Has A Surface Temperature Of 290 C Q 20 Marks And Emissivity 1 (27.31 KiB) Viewed 88 times

: A Disc Of A Diameter D 120 Mm And Thickness Of 1 Mm Has A Surface Temperature Of 290 C Q 20 Marks And Emissivity 2 (27.31 KiB) Viewed 88 times

: A Disc Of A Diameter D 120 Mm And Thickness Of 1 Mm Has A Surface Temperature Of 290 C Q 20 Marks And Emissivity 3 (27.31 KiB) Viewed 88 times

A disc of a diameter D = 120 mm, and thickness of 1 mm, has a surface temperature of 290°C [Q: 20 marks] and emissivity E = 0.8. The disc is oriented horizontally and subjected to a cooling process in quiescent, ambient air and large surroundings for which T.. = Tsur = 30°C. Neglect the heat transfer at the side of the disc, [Take 0 = 5.67 x 10-8 W/m2.K4; g = 9,81 m/s?1 a) Calculate the rate of heat transfer for top and bottom surfaces during cooling process? [16 marks) b) Check the situation whether the convection is forced, natural or mixed convection in case the disc is subject to moving air with a velocity of 3 m/s. 14 marks)