Transient Conduction The Lumped Capacitance Method Chapter Five

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Transient Conduction: The Lumped Capacitance Method Chapter Five Sections 5. 1 through 5. 3

Transient Conduction: The Lumped Capacitance Method Chapter Five Sections 5. 1 through 5. 3

Lumped Capacitance Method The Lumped Capacitance Summary If possible, start by checking the Bi

Lumped Capacitance Method The Lumped Capacitance Summary If possible, start by checking the Bi is less than 0. 1 Calculate the Thermal Time Constant Calculate the Temperature as a function of time Calculate the Energy Transferred as a function of time

Problem: Furnace Start-up Problem 5. 19: Heating of coated furnace wall during start-up. SCHEMATIC:

Problem: Furnace Start-up Problem 5. 19: Heating of coated furnace wall during start-up. SCHEMATIC:

Problem: Furnace Start-up (cont. ) Hence, with <

Problem: Furnace Start-up (cont. ) Hence, with <

Problem: Furnace Start-up (cont. ) <

Problem: Furnace Start-up (cont. ) <

Annealing Steel balls that are 12 mm in diameter are annealed by heating them

Annealing Steel balls that are 12 mm in diameter are annealed by heating them to 1500 K, then slowly cooling them down to 400 K. They are cooled in air that is 325 K, with a convection coefficient of h = 20 [W/m 2 -K]. Estimate how much time the cooling process will take For steel, use properties of k = 40 [W/m-K], density = 7800 [kg/m 3], and c = 600 [J/kg-K] Calculate the Biot Number: Lc = r 0/3 for a sphere!

Annealing Steel balls that are 12 mm in diameter are annealed by heating them

Annealing Steel balls that are 12 mm in diameter are annealed by heating them to 1500 K, then slowly cooling them down to 400 K. They are cooled in air that is 325 K, with a convection coefficient of h = 20 [W/m 2 -K]. Estimate how much time the cooling process will take For steel, use properties of k = 40 [W/m-K], density = 7800 [kg/m 3], and c = 600 [J/kg-K] Note: We are ignoring radiation heat transfer. Early in the cooling process this might be significant. Since we ignored a loss term, the actual cooling time might be shorter than what we calculated.

Heating Steel Shafts Steel cylinders are put in an oven for heat treatment. The

Heating Steel Shafts Steel cylinders are put in an oven for heat treatment. The initial temperature of the cylinders is 300 K. The oven is at 1200 K. Estimate how much time it will take for the center of the cylinders to reach 800 K. Calculate the Biot Number: Lc = r 0/2 for a cylinder!

Heating Steel Shafts Steel cylinders are put in an oven for heat treatment. The

Heating Steel Shafts Steel cylinders are put in an oven for heat treatment. The initial temperature of the cylinders is 300 K. The oven is at 1200 K. Estimate how much time it will take for the center of the cylinders to reach 800 K.

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