/ CH-206: Transfer Processes-1 Department of Chemical Engineering, lIT Roorkee Topic: Radiation heat Transfer 1. The configuration of a furnace can be approximated as an equilateral triangular duct which is sufficiently long that the end effects are negligible. The hot wall is maintained at T1= 900 K and has an emissivity £1= 0.8. The cold wall is at T2 = 400K and has an emissivity £2= 0.8. The third wall is redirecting zone for which Q3 = O.Calculate the net radiation heat flux leaving the hot wall. Ii :::-7tJDK. 2. Consider a cylindrical furnace with ro = H = 1 m. The top surface ~, ~o.g -t' (surface-I) and the base surface (surface-2) of the furnace has emissivities £1 = 0.8 and £2= 0.4, respectively and are maintained at 15 uniform temperatures T1= 700 K, T2= SOOK.The side surface closely -;::'-riJD approximated as a black body and is maintained at a temperature of T3 = 400 K. Determine the net rate of radiation heat transfer at each ® 5.. J-\ B/~ surface during steady operation and explain how these surfaces can be maintained at specified temperature. CD 3. Two square plate each 1 m by 1m are parallel to and directly opposite each other at a distance 1m. The hot plate is at T1 = 800K and has an emissivity £1= 0.8. The colder plate is at T2 = 600K and _ also has an emissivity £2 = 0.8. The radiation heat exchange takes place between the plates as well as with a large ambient at T3 ~ 300K through the opening between the plates. Calculate the net heat transfer rate by radiation at each plate to the ambient. t ft:fj]/ I "" 1 . ~ c2-:-' 11M Q) 0·8 ..-:y (8'([.3) 4. Two parallel surfaces dA1 and A2 are arranged as shown in Fig.4. Show that by a suitable application of view factor algebra, the view factor for this configuration can be constructed by the algebraic sum of view factors, which can be determined from the standard chart. AI ~ A:J- ~ A -/"' -" (... QI/~ "'r/ - E-h- fbI -- R. 9-1 =- Q1 ) NJ.- . 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