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A long steel bar of radius R=2.5 cm, k =50 W/(m °C), p= 7800 kg/m), and...
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...
Steel balls 12 mm in diameter are annealed by heating to 1100 K and then slowly...
Steel balls 12 mm in diameter are annealed by heating to 1100 K
and then slowly cooling to 390 K in an air environment for which
?T?= 325 K and h= 20 W/m2·K. Assuming the properties of
the steel to be k= 40 W/m·K, ?= 7800 kg/m3, and c= 600
J/kg·K, estimate the time required for the cooling process.
Problem 5.007 Your answer is incorrect. Try again. Steel balls 12 mm iri diameter are annealed by heatin time required for...
Exercise 1.18 A freshly forged flat steel ( λ-56, 16 W/m K , c.-450 J/kg K, ρ-7800 kg/m2 ) is immersed in an oil bath at 800°C. The steel surface immediately reaches the temperature of the oil ba...
Exercise 1.18 A freshly forged flat steel ( λ-56, 16 W/m K , c.-450 J/kg K, ρ-7800 kg/m2 ) is immersed in an oil bath at 800°C. The steel surface immediately reaches the temperature of the oil bath of 50°C. Neglect marginal effects and consider the steel as a plate with a thickness of 10 mm. What are the steel temperatures in 1 mm, 4 mm and 5 mm below the surface? a) after 1/100 second? b) after 1/10s c)...
Q2 (a) A 12 mm diameter mild steel sphere (k = 42.5 W/m K) is exposed...
Q2 (a) A 12 mm diameter mild steel sphere (k = 42.5 W/m K) is exposed to cooling airflow at 27 "C resulting in the convective coefficient, h = 114 W/m' K. The relevant properties of mild steel are given as follows: Density p= 7850 kg/m . Specific heat c = 475 J/kg K and thermal diffusivity a = 0.043 m/hr Determine: (i) Time required to cool the sphere (lumped parameter system) from 540 °C to 95°C. [7 marks] (ii)...
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%)
1. A steel tube [k 15 W/(m.°C)] of outside diameter 7.6 cm and thickness 1.3 cm...
1. A steel tube [k 15 W/(m.°C)] of outside diameter 7.6 cm and thickness 1.3 cm is covered with an insulation material [k 0.2 W/(m. C)] of thickness 2 cm. A hot gas at 320°C with a heat transfer coefficient of 200 W/(m2.C) flows inside the tube. The outer surface of the insulation is exposed to cooler air at 20°C with a heat transfer coefficient of 50 W/(m2·°C). Calculate a) The heat loss from the tube to the air for...
4. Hardening of ball bearings made from Type 440C stainless steel, one of the hardest stainless...
4. Hardening of ball bearings made from Type 440C stainless steel, one of the hardest stainless steels, is accomplished by heating the bearings to 1010 to 1065 °C then quenching (rapidly cooling) them in oil Consider bearings 24 mm in diameter at an initial uniform temperature of 1050 °C, cooled in an oil bath at 50 °C in which the convective heat transfer coefficient is 600 W/(m2 K). Properties of Type 440C Stainless Steel:t Density, 7800 kg/m3 Thermal conductivity, 24...
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...
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...
1) 2.5 m/s of air at 150°C is used to heat 0.35 kg/s of 20°C water....
1) 2.5 m/s of air at 150°C is used to heat 0.35 kg/s of 20°C water. The heat exchanger is a finned-tube cross flow heat exchanger with both sides unmixed. The overall heat transfer coefficient associated with the hot side is 120 W/(m2 °C). The hot-side area is 20 m². Assume a constant specific heat for air and water of Gezic = 1.005 kJ/(kg °C), Senator = 4.2 kJ/(kg °C). The pressure of the hot air is P = 1.0...
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...
Steel balls 12 mm in diameter are annealed by heating to 1100 K
and then slowly cooling to 390 K in an air environment for which
?T?= 325 K and h= 20 W/m2·K. Assuming the properties of
the steel to be k= 40 W/m·K, ?= 7800 kg/m3, and c= 600
J/kg·K, estimate the time required for the cooling process.
Problem 5.007 Your answer is incorrect. Try again. Steel balls 12 mm iri diameter are annealed by heatin time required for...
Exercise 1.18 A freshly forged flat steel ( λ-56, 16 W/m K , c.-450 J/kg K, ρ-7800 kg/m2 ) is immersed in an oil bath at 800°C. The steel surface immediately reaches the temperature of the oil bath of 50°C. Neglect marginal effects and consider the steel as a plate with a thickness of 10 mm. What are the steel temperatures in 1 mm, 4 mm and 5 mm below the surface? a) after 1/100 second? b) after 1/10s c)...
Q2 (a) A 12 mm diameter mild steel sphere (k = 42.5 W/m K) is exposed to cooling airflow at 27 "C resulting in the convective coefficient, h = 114 W/m' K. The relevant properties of mild steel are given as follows: Density p= 7850 kg/m . Specific heat c = 475 J/kg K and thermal diffusivity a = 0.043 m/hr Determine: (i) Time required to cool the sphere (lumped parameter system) from 540 °C to 95°C. [7 marks] (ii)...
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%)
1. A steel tube [k 15 W/(m.°C)] of outside diameter 7.6 cm and thickness 1.3 cm is covered with an insulation material [k 0.2 W/(m. C)] of thickness 2 cm. A hot gas at 320°C with a heat transfer coefficient of 200 W/(m2.C) flows inside the tube. The outer surface of the insulation is exposed to cooler air at 20°C with a heat transfer coefficient of 50 W/(m2·°C). Calculate a) The heat loss from the tube to the air for...
4. Hardening of ball bearings made from Type 440C stainless steel, one of the hardest stainless steels, is accomplished by heating the bearings to 1010 to 1065 °C then quenching (rapidly cooling) them in oil Consider bearings 24 mm in diameter at an initial uniform temperature of 1050 °C, cooled in an oil bath at 50 °C in which the convective heat transfer coefficient is 600 W/(m2 K). Properties of Type 440C Stainless Steel:t Density, 7800 kg/m3 Thermal conductivity, 24...
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...
1) 2.5 m/s of air at 150°C is used to heat 0.35 kg/s of 20°C water. The heat exchanger is a finned-tube cross flow heat exchanger with both sides unmixed. The overall heat transfer coefficient associated with the hot side is 120 W/(m2 °C). The hot-side area is 20 m². Assume a constant specific heat for air and water of Gezic = 1.005 kJ/(kg °C), Senator = 4.2 kJ/(kg °C). The pressure of the hot air is P = 1.0...
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