Furnace Simulation via Zoning

Example 10 Furnace Simulation via Zoning The furnace chamber depicted in Fig. 5-20 is heated by combustion gases passing through 20 vertical radiant tubes which are backed by refractory sidewalls. The tubes have an outside diameter of D = 5 in (12.7 cm) mounted on C = 12 in (4.72 cm) centers and a gray body emissivity of 0.8. The interior (radiant) portion of the furnace is a 6 x 8 x 10 ft rectangular parallelepiped with a total surface area of 376 ft2 (34.932 m2). A 50-fL (4.645-m2) sink is positioned centrally on the floor of the furnace. The tube and sink temperatures are measured with embedded thermocouples as 1500 and 1200°F, respectively. The gray refractory emissivity may be taken as 0.5. While all other refractories are assumed to be radiatively adia- 

Compute direct exchange areas There are Z = 6 unique direct exchange areas. These are obtained from Eqs. (5-114) and view factor algebra. The final array of direct exchange areas is  

Emissive power and wall flux input data 1200  

Compute refractory emissive powers from known flux inputs Q and using 

Compute flux values and final zone temperatures  

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