50 mm10 mmQ9: A spherical container holding a cryogenicfluid at – 140°C and having an outerdiameter of 0.4 m is insulated with three layers each of 50 mm thick insulations ofkl = 0.02, k2 = 0.06 and k3 = 0.16 W/m. K (starting from the inside). The outsideis exposed to air at 30°C with h 15 W/m.K. Determine the heat gain and thevarious surface temperatures.k-0.16 WimkK0.06 Wimkk, = 0.02 Wimkh 15 Wim'k- 140°CT=30°CQ10: A furnace wall is three layers, the first layer of insulation brick of 12 cmthickness of conductivity 0.6 W/m. K. The face is exposed to gases at 870°C with aconvection coefficient ofl 10 W/m.K. This layer is backed by a 10 cm layer offirebrick of conductivity 0.8 W/m. K. There is a contact resistance between thelayers of 2.6 x 10 m °C/W. The third layer is the plate backing of 10 mmthickness of conductivity 49 W/m. K. The contact resistance between the secondand third layers is 1.5 x 10 m².°C/W. The plate is exposed to air at 30°C with aconvection coefficient of 15 W/m. K. Determine the heat flow, the surfacetemperatures and the overall heat transfer coefficient.870°Cn, 110 Wim'k15 Wim'k870°C30°C30°C12 m01m o011: Two slabs, each 120 mm thick, have thermal conductivities of 14.5 W/m°Cand 210 W/m°C. These are placed in contact, but due to roughness, only 30 percentof area is in contact and the gap in the remaining area is 0.025 mm thick and isfilled with air. If the temperature of the face of the hot surface is at 220°C and theoutside side surface of other slab is at 30°C, determine:(i) Heat flow through the composite system. (ii) The contact resistance andtemperature drop in contact.Assume that the conductivity of air is 0.032 W/m°C and that half of the contact (ofthe contact area) is due to either metal6.

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Q9: A spherical container holding a cryogenicfluid at – 140°C and having an outer diameter of 0.4 m is insulated with three layers each of 50 mm thick insulations of kl = 0.02, k2 = 0.06 and k3 = 0.16 W/m. K (starting from the inside). The outside is exposed to air at 30°C with h = 15 W/mK. Determine the heat gain and the various surface temperatures. k=0.16 Wimk * k=0.06 Wimk K,=0.02 Wimk he 15 Wimk - 140°c T 30°C

Q9: A spherical container holding a cryogenicfluid at – 140°C and having an outer diameter of 0.4 m is insulated with three layers each of 50 mm thick insulations of kl = 0.02, k2 = 0.06 and k3 = 0.16 W/m. K (starting from the inside). The outside is exposed to air at 30°C with h = 15 W/mK. Determine the heat gain and the various surface temperatures. k=0.16 Wimk * k=0.06 Wimk K,=0.02 Wimk he 15 Wimk - 140°c T 30°C

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.30P: 2.30 An electrical heater capable of generating 10,000 W is to be designed. The heating element is...

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