A long steel bar with a diameter of 4 cm (ρ = 7840 kg / m3...
A long steel bar with a diameter of 4 cm (ρ = 7840 kg / m3 , cp = 580 J / kg ° K, k = 52 W / mK, α = 1.21x10-5 m2 / s), internal enters the 2 m long moving belt heat treatment furnace at ambient temperature of 900 ° C at 40 ° C. Since the film coefficient in the oven is 100 W / m2K, the center axis temperature of the bar at the oven exit is 60 ° C. in order to be
a.) Find the elapsed time.
b.) Find the transition speed (band speed) of the steel rod.
Homework Answers
Problem 2: A stainless steel rod (k-21 W/m-K, p-8000 kg/m3, C,,-570 J/kg-K) with diameter D-10 mm is heat-treated as it...
Problem 2: A stainless steel rod (k-21 W/m-K, p-8000 kg/m3, C,,-570 J/kg-K) with diameter D-10 mm is heat-treated as it passes through a furnace at a speed of 2 cm/s. The furnace has a convection coefficient of 80 W/m2-K and an air temperature of 900°C. The furnace is 3 m long, and the stainless steel enters at 20°C. (a) Using a control volume of length S traveling with the rod, develop a differential equation for the rate of change of...
Оооо оооо оооо оооо т. Steel bar A steel bar, 80 mm in diameter and 200...
Оооо оооо оооо оооо т. Steel bar A steel bar, 80 mm in diameter and 200 mm long, with an emissivity of 0.6, is removed from a furnace at 455ºC and suddenly submerged in a quiescent water 9 bath under atmospheric pressure. Assume evaporation of saturated water at 1 atm to saturated (not D superheated) steam. L Estimate the initial heat transfer rate from the bar, 9, Properties of saturated water at 100°C at 277.5°C P. (kg/m²) = 957.9 P...
In one stage of an annealing process, a 304 stainless steel sheet is taken from 300...
In one stage of an annealing process, a 304 stainless steel sheet is taken from 300 K to 1250 K as is passes through an electrically heated oven at a speed of vs= 10 mm/s. The sheet thickness and width are ts= 8 mm and ws= 2 m, respectively, while the height, width and length of the oven are ho= 2 m, wo= 2.4 m and lo= 25 m, respectively. The top and four sides of the oven are exposed...
QUESTION TWO Carbon steel balls (p 7833 kg/m3, k-54 W/m K, cp 0.465 kJ/kg.0C and a-1.474...
QUESTION TWO Carbon steel balls (p 7833 kg/m3, k-54 W/m K, cp 0.465 kJ/kg.0C and a-1.474 x 10-6 m2/s) 10 mm in diameter are annealed by heating them first to 900'C in a furnace and then allowing them to cool slowly to 100°C in ambient air at 35°C. If the average heat transfer coefficient is 75 W/m2 K, determine how long the annealing process will take. If 2500 balls are to be annealed per hour, determine the total rate of...
4. A long square steel bar 2L - 7 cm wide by 21 - 7 cm...
4. A long square steel bar 2L - 7 cm wide by 21 - 7 cm high having a thermal conductivity k, = 14 W/n'c and a thermal diffusivity a 3.63x10 m/s is hot rolled at T. - 615°C and then cooled by air issuing from jets at T. -30°c. After t - 287 s have elapsed, the temperature at the center of the bar T(0,0,t) - 240c and the temperature at the corners of the bar T(L,Lt) - 125c....
Problem 2. A long 6.5 cm diameter solid cylinder steel (K 16.3 W/m. K,p 7817 kg/m3,...
Problem 2. A long 6.5 cm diameter solid cylinder steel (K 16.3 W/m. K,p 7817 kg/m3, Cp 460 J/kg.k). It's initially at a uniform temperature of T 150°C. It is suddenly exposed to a convection environment with h-285 W/m2 K and Too 50°C. Calculate the temperature at 1.) the axis of the cylinder, and 2.) a 2.5 cm radial distance after 5 min of exposure to the cooling flow. (20%)
Water enters a 5-mm diameter and 13-m long tube at 15 °C with a velocity of...
Water enters a 5-mm diameter and 13-m long tube at 15 °C with a velocity of 0.3 m/s and leaves at 45 °C. The tube is subject to a uniform heat flux of 2000 W/m2. Assume the following properties of water: p = 996 kg/m3, Cp = 4178 J/kg.K, K = 0.615 W/m.K. u = 0.798 x 10-kg/mus. Pe=5.42. (7) What is the average convective heat transfer coefficient considering the entire length of the pipe? (a) 791 W/m2K (b) 681...
A long steel bar of radius R=2.5 cm, k =50 W/(m °C), p= 7800 kg/m), and...
A long steel bar of radius R=2.5 cm, k =50 W/(m °C), p= 7800 kg/m), and c = 0.5 kJ/(kg. . °C) is to be annealed by cooling slowly from 800.°C to 100.°C in an environment at temperature 50.°C. If the heat transfer coefficient between the environment and the surface of the bars is h = 45 W/(m .°C), determine the time required for the annealing process using lumped system analysis.
3. Applesauce at a food processing plant exits a tank at an initial temperature of 90°C....
3. Applesauce at a food processing plant exits a tank at an initial temperature of 90°C. It flows through a 6 m section of 40 mm diameter pipe at speed of 1 cm/sec. The pipe is wrapped in 5 mm of insulation (k 0.3 W/mK), and has an inside heat transfer coefficient of hi = 100 W/m2K and an outside heat transfer coefficient of 8 W/m2K. losing heat to the environment at To10°C. The applesauce next enters a 1 m...
Consider a long solid bar (k=30W/m K and α 12X10-6 m /s) ofAare cro s section that is initially at uniform room tempera...
Consider a long solid bar (k=30W/m K and α 12X10-6 m /s) ofAare cro s section that is initially at uniform room temperature of 150° C. The cross seftion of the bar is 20 cm X 20 cm in size. All four side of the bar are subjected to donJeation td the ambient air at T-25oC with a heat transfer coefficient of h t45 W/m2K. Using the explicit finite difference method with a mesh Δ x = Δ y-10cm</determine the...
Problem 2: A stainless steel rod (k-21 W/m-K, p-8000 kg/m3, C,,-570 J/kg-K) with diameter D-10 mm is heat-treated as it passes through a furnace at a speed of 2 cm/s. The furnace has a convection coefficient of 80 W/m2-K and an air temperature of 900°C. The furnace is 3 m long, and the stainless steel enters at 20°C. (a) Using a control volume of length S traveling with the rod, develop a differential equation for the rate of change of...
Оооо оооо оооо оооо т. Steel bar A steel bar, 80 mm in diameter and 200 mm long, with an emissivity of 0.6, is removed from a furnace at 455ºC and suddenly submerged in a quiescent water 9 bath under atmospheric pressure. Assume evaporation of saturated water at 1 atm to saturated (not D superheated) steam. L Estimate the initial heat transfer rate from the bar, 9, Properties of saturated water at 100°C at 277.5°C P. (kg/m²) = 957.9 P...
QUESTION TWO Carbon steel balls (p 7833 kg/m3, k-54 W/m K, cp 0.465 kJ/kg.0C and a-1.474 x 10-6 m2/s) 10 mm in diameter are annealed by heating them first to 900'C in a furnace and then allowing them to cool slowly to 100°C in ambient air at 35°C. If the average heat transfer coefficient is 75 W/m2 K, determine how long the annealing process will take. If 2500 balls are to be annealed per hour, determine the total rate of...
4. A long square steel bar 2L - 7 cm wide by 21 - 7 cm high having a thermal conductivity k, = 14 W/n'c and a thermal diffusivity a 3.63x10 m/s is hot rolled at T. - 615°C and then cooled by air issuing from jets at T. -30°c. After t - 287 s have elapsed, the temperature at the center of the bar T(0,0,t) - 240c and the temperature at the corners of the bar T(L,Lt) - 125c....
Problem 2. A long 6.5 cm diameter solid cylinder steel (K 16.3 W/m. K,p 7817 kg/m3, Cp 460 J/kg.k). It's initially at a uniform temperature of T 150°C. It is suddenly exposed to a convection environment with h-285 W/m2 K and Too 50°C. Calculate the temperature at 1.) the axis of the cylinder, and 2.) a 2.5 cm radial distance after 5 min of exposure to the cooling flow. (20%)
Water enters a 5-mm diameter and 13-m long tube at 15 °C with a velocity of 0.3 m/s and leaves at 45 °C. The tube is subject to a uniform heat flux of 2000 W/m2. Assume the following properties of water: p = 996 kg/m3, Cp = 4178 J/kg.K, K = 0.615 W/m.K. u = 0.798 x 10-kg/mus. Pe=5.42. (7) What is the average convective heat transfer coefficient considering the entire length of the pipe? (a) 791 W/m2K (b) 681...
A long steel bar of radius R=2.5 cm, k =50 W/(m °C), p= 7800 kg/m), and c = 0.5 kJ/(kg. . °C) is to be annealed by cooling slowly from 800.°C to 100.°C in an environment at temperature 50.°C. If the heat transfer coefficient between the environment and the surface of the bars is h = 45 W/(m .°C), determine the time required for the annealing process using lumped system analysis.
3. Applesauce at a food processing plant exits a tank at an initial temperature of 90°C. It flows through a 6 m section of 40 mm diameter pipe at speed of 1 cm/sec. The pipe is wrapped in 5 mm of insulation (k 0.3 W/mK), and has an inside heat transfer coefficient of hi = 100 W/m2K and an outside heat transfer coefficient of 8 W/m2K. losing heat to the environment at To10°C. The applesauce next enters a 1 m...
Consider a long solid bar (k=30W/m K and α 12X10-6 m /s) ofAare cro s section that is initially at uniform room temperature of 150° C. The cross seftion of the bar is 20 cm X 20 cm in size. All four side of the bar are subjected to donJeation td the ambient air at T-25oC with a heat transfer coefficient of h t45 W/m2K. Using the explicit finite difference method with a mesh Δ x = Δ y-10cm</determine the...
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