2. A composite furnace wall is made up of a 14 in. lining of magnetite refractory brick, a 5.3 in. thickness of 85% magnesia, and a steel casing 1.10 in. thick. Flue gas temperature is 2200°F and the boiler room is at 81°F. Gas side film coefficient is 15 Btu/hr-ft2-"F and air side is 4. Determine the thermal current Q/A.

2. A composite furnace wall is made up of a 14 in. lining of magnetite refractory brick, a 5.3 in. thickness of 85% magnesia, and a steel casing 1.10 in. thick. Flue gas temperature is 2200°F and the boiler room is at 81°F. Gas side film coefficient is 15 Btu/hr-ft2-"F and air side is 4. Determine the thermal current Q/A.

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.

Chapter9: Heat Transfer With Phase Change

Section: Chapter Questions

Problem 9.36P

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1. A composite furnace wall is made up of a 12-in. lining of magnesite refractory brick, a 5-in.thickness of 85% magnesia, and a steel casing 0.10-in. thick. Flue gas temperature is 2200 F andthe boiler room is at 80 F. Gas side film coefficient is 15 Btu/hr-sq.ft-F and air side is 4.0.Determine:a. The thermal current Q/Ab. Interface temperaturesc. Effect on thermal current and inside refractory wall temperature if the magnesia insulation weredoubled.
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