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A flaked cereal is of thickness 2L1.2 mm. The
Chapter 5, Problem 5.10(choose chapter or problem)
A flaked cereal is of thickness 2L?1.2 mm. The density,specific heat, and thermal conductivity of the flake are??700 kg/m3, cp?2400 J/kg?K, and k?0.34 W/m?K,respectively. The product is to be baked by increasing itstemperature from Ti?20C to Tf ?220C in a convec-tion oven, through which the product is carried on a con-veyor. If the oven is Lo?3 m long and the convectionheat transfer coefficient at the product surface and ovenair temperature are h?55 W/m2?K and T??300C,respectively, determine the required conveyor velocity,V. An engineer suggests that if the flake thickness isreduced to 2L?1.0 mm the conveyor velocity can beincreased, resulting in higher productivity. Determinethe required conveyor velocity for the thinner flake.
Questions & Answers
QUESTION:
A flaked cereal is of thickness 2L?1.2 mm. The density,specific heat, and thermal conductivity of the flake are??700 kg/m3, cp?2400 J/kg?K, and k?0.34 W/m?K,respectively. The product is to be baked by increasing itstemperature from Ti?20C to Tf ?220C in a convec-tion oven, through which the product is carried on a con-veyor. If the oven is Lo?3 m long and the convectionheat transfer coefficient at the product surface and ovenair temperature are h?55 W/m2?K and T??300C,respectively, determine the required conveyor velocity,V. An engineer suggests that if the flake thickness isreduced to 2L?1.0 mm the conveyor velocity can beincreased, resulting in higher productivity. Determinethe required conveyor velocity for the thinner flake.
ANSWER:Problem 5.10
A flaked cereal is of thickness 2L=1.2 mm. The density,specific heat, and thermal conductivity of the flake are p = 700 kg/m3, cp = 2400 J/kg.K, and k = 0.34 W/m.K, respectively. The product is to be baked by increasing its temperature from Ti = 20°C to Tf = 220°C in a convec-tion oven, through which the product is carried on a con-veyor. If the oven is Lo = 3 m long and the convection heat transfer coefficient at the product surface and ovenair temperature are h = 55 W/m2.K and T= 300°C,respectively, determine the required conveyor velocity,V. An engineer suggests that if the flake thickness is reduced to 2L=1.0 mm the conveyor velocity can be increased, resulting in higher productivity. Determinethe required conveyor velocity for the thinner flake.
Step by step solution
Step 1 of 2
The characteristic length of the cereal is
The biot number will be
Therefore,the lumped capacitance approximation is valid,and the time will be
