5.10 A steel sphere (AISI 1010), 100 mm in diameter, iscoated with a dielectric material layer of thickness2 mm and thermal conductivity 0.04 W/mK. Thecoated sphere is initially at a uniform temperature of500°C and is suddenly quenched in a large oil bath forwhich T = 100°C and h = 3000 W/m² K. Estimate thetime required for the coated sphere temperature to reach150°C. Hint: Neglect the effect of energy storage in thedielectric material, since its thermal capacitance (pcV)is small compared to that of the steel sphere.

The diameter of sphere is The thickness of dielectric matrial is The thermal conductivity of…

5.10 A steel sphere (AISI 1010), 100 mm in diameter, is coated with a dielectric material layer of thickness 2 mm and thermal conductivity 0.04 W/m. K. The coated sphere is initially at a uniform temperature of 500°C and is suddenly quenched in a large oil bath for which Tỵ = 100°C and h = 3000 W/m² · K. Estimate the time required for the coated sphere temperature to reach 150°C. Hint: Neglect the effect of energy storage in the dielectric material, since its thermal capacitance (pcV) is small compared to that of the steel sphere.

5.10 A steel sphere (AISI 1010), 100 mm in diameter, is coated with a dielectric material layer of thickness 2 mm and thermal conductivity 0.04 W/m. K. The coated sphere is initially at a uniform temperature of 500°C and is suddenly quenched in a large oil bath for which Tỵ = 100°C and h = 3000 W/m² · K. Estimate the time required for the coated sphere temperature to reach 150°C. Hint: Neglect the effect of energy storage in the dielectric material, since its thermal capacitance (pcV) is small compared to that of the steel sphere.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter6: Forced Convection Over Exterior Surfaces

Section: Chapter Questions

Problem 6.26P

See similar textbooks

Similar questions

Example 3.3: The temperature at the center of a tender-boiled potato needs to be 98.9°C. Let's take a potato with 4 cm diameter at 5°C and and put it in vigorously boiling water at 100 °C, where convection coefficient is 1200 W/m². c. How much time will it take to cook the potato? Potato properties: density p=1070 kg/m³, conductivity k=0.8 W/m.°c, specific heat c = 3400 J/kg-°C.
3.4 Estimate the rate of heat loss due to radiation from a covered pot of water at 95 ° C. How does this compare with the 60 W that is lost due only to convection and conduction losses? What amount of energy input would be needed to maintain the water at its boiling point for 30 minutes? The polished stainless steel pot is cylindrical, 20 cm in diameter and 14 cm high, with a tight-fitting flat cover. The air temperature in the kitchen is about 25 ° C. State any assumptions you make in deriving your estimates
A steel sphere (AISI 1010), 100 mm in diameter, is coated with a dielectric material layer of thickness 1.75 mm and thermal conductivity 0.04 W/m.K. The coated sphere is initially at a uniform temperature of 500°C and is suddenly quenched in a large oil bath for which T = 100°C and h = 3000 W/m².K. Estimate the time, in h, required for the coated sphere temperature to reach 150°C. Hint: Neglect the effect of energy storage in the dielectric material, since its thermal capacitance (pc)is small compared to that of the steel sphere. t = h
An underwater sonar that maps the ocean bathymetry is encapsulated in a sphere with a diameter of 85 mm. During operation, the sonar generates heat at a rate of 300W. What is the sonar surface temperature when it’s located in a water column where the temperature is 15o C and the water current is 1 m/sec? The sonar was pulled out of the water without turning it off, thus, it was still working. The air temperature was 15o C and the air speed was 3 m/sec. What was the sonar surface temperature? Was there any reason for concern?
Stainless steel (AISI 304) ball bearings, which have been uniformly heated to 850°C, are hardened by quenching them in an oil bath that is maintained at 40°C. The ball diameter is 12.5 mm, and the convection coefficient associated with the oil bath is 1000 W/m².K. (a) If quenching is to occur until the surface temperature of the balls reaches 100°C, how long, in s, must the balls be kept in the oil? What is the center temperature, in °C, at the conclusion of the cooling period? (b) If 10,000 balls are to be quenched per hour, what is the rate at which energy must be removed, in kW, by the oil bath cooling system in order to maintain its temperature at 40°C? Evaluate the properties of the stainless steel (AISI 304) at 500 K. Part A If quenching is to occur until the surface temperature of the balls reaches 100°C, how long, in s, must the balls be kept in the oil? What is the center temperature, in °C, at the conclusion of the cooling period? t = T₁ = i i S °℃
Please show all steps not Ai generated they have been wrong and I need to understand whats goin on. A steel sphere (AISI 1010), 100 mm in diameter, is coated with a dielectric material layer of thickness 2 mm and thermal conductivity 0.04 W/m • K. The coated sphere is initially at a uniform temperature of 500°C and is suddenly quenched in a large oil bath for which To = 100°C and h = 3000 W/m • K. Estimate the time required for the coated sphere temperature to reach 150°C. Hint: Neglect the effect of energy storage in the dielectric material, since its thermal capacitance (pcV) is small compared to that of the steel sphere.
A 10.0-cm cube of stainless steel is initially at 500oC. It is suddenly immersed in a tank of oil maintained at 100oC. The convection coefficient is 1000 W/m2×oC. Calculate the temperature at the center of one face after 1 min.Data: stainless steel properties, k = 22 W/m×oC, r = 7,689 kg/m3, c = 460 J/kg×oC.
(a) The heating power generated by the nuclear heating rod and the inner temperature of the metallic cylinder, T2. (b) The temperature liquid X, which is located between the nuclear heating rod and the meatllic cylinder, Tliquid. (c) The temperature at the surface of the heating rod, T1. (d) If the salt solution temperature is 300 degree Celcius, what is the value of convection heat transfer coefficient, h of the salt solution ? (e) If the heating rod is not covered by metallic cylinder and corresponds to the result of part (c) and (d), how much the rate of energy transfer to the salt solution ? (f) Compare and discuss the difference of heat transfer with and without the matallic cylinder.
Thermal conductivity is lower for (a) wood (b) air (c) water at 100°C steam at 1 bar
A composite plane wall consisting of materials, 1.5-in steel (k = 312 BTU-in/HR.ft2.0F) and 2-in aluminum (k = 1400 BTU-in/HR.ft2.0F), separates a hot gas at Ti = 2000F, hi = 2 BTU/HR.ft2.0F, from cold gas at To = 80 deg F, ho = 5. If the hot fluid is on the aluminum side, find: a) Transmittance, U; b) The heat through 100 sq. ft of the surface under steady state condition and c) The interface temperature at the junction of the metals.
5.6 Steel balls 12 mm in diameter are annealed by heating to 1150 K and then slowly cooling to 400 K in an air envi- ronment for which T325 K and h = 20 W/m².K. Assuming the properties of the steel to be k = 40 W/mK, p= 7800 kg/m³, and c = 600 J/kg K, estimate the time required for the cooling process.
A long insulated tube is doped with an exothermic ma- terial which generates steady and uniform heat at rate of è [W/m³]. The tube has an inner radius r₁ and outer radius r₂. The temperature of the outer insulated sur- face is T₂. This tube is used to heat a liquid flowing through it. (a) Write the governing differential equation and boundary conditions to determine the tempera- ture distribution inside the tube. (b) What is the heat flux supplied to the liquid by the tube? e (√₂²-1₁²) / 21₁ 1 Fluid Figure 2: Schematic Insulation T₂ N