A large plate of aluminum 5.0 cm thick and initially at 200°C js suddenly exposed to the convection environment of Example 4-5. Calculate the temmperature at adepth of 1.25 cm/irom one of the faces 1 min after the plate has been exposed to the environment. How much energy has been removed per unit area from the plate in this time? 2L-5cm L = 2.5cm - Ti's 200c 군- Imin = (*60 L=2.5cm %3D %3D - 60 S Note: (x) is measured from center (a)

A large plate of aluminum 5.0 cm thick and initially at 200°C js suddenly exposed to the convection environment of Example 4-5. Calculate the temmperature at adepth of 1.25 cm/irom one of the faces 1 min after the plate has been exposed to the environment. How much energy has been removed per unit area from the plate in this time? 2L-5cm L = 2.5cm - Ti's 200c 군- Imin = (*60 L=2.5cm %3D %3D - 60 S Note: (x) is measured from center (a)

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.3P: 2.3 The shield of a nuclear reactor is idealized by a large 25-cm-thick flat plate having a thermal...

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2.3 The shield of a nuclear reactor is idealized by a large 25-cm-thick flat plate having a thermal conductivity of . Radiation from the interior of the reactor penetrates the shield and there produces heat generation that decreases exponentially from a value of at the inner surface to a value of at a distance of 12.5 cm from the interior surface. If the exterior surface is kept at 38°C by forced convection, determine the temperature at the inner surface of the field. Hint: First set up the differential equation for a system in which the heat generation rate varies according to .
Silver shafts of 0.1 m diameter are heat treated in a gas-fired furnace whose gases are at 1200 K and provide a convection coefficient of 50 W/m².K. The shafts enter the furnace at 400 K and they remain in the furnace for 1000 s. Determine the centerline temperature of the shaft when it comes out of the furnace?
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.
3- You have experienced convection cooling if you have ever extended your handout of the window of a moving vehicle or into a flowing water stream. With the surface of your hand at a temperature of 30 oC, determine the convection heat flux for a) a vehicle speed of 35 km/h in air at -5 oC with convection coefficient of 40 W/m2 .K and b) a velocity of 0.2 m/s in a water stream at 10 oC with convection coefficient of 900 W/m2.K. Which condition would feel colder? Contrast theseresults with a heat loss of approximately 30 W/m2 under normal room conditions.
The rear window of an automobile is defogged by passing warm air over its inner surface. If the warm air is at T∞,i=40°C and the corresponding convection coefficient is hi=30 W/m2·K, what are the inner and outer surface temperatures, in °C, of 4-mm-thick window glass, if the outside ambient air temperature is T∞,o= -27.5°C and the associated convection coefficient is ho=65 W/m2·K? Evaluate the properties of the glass at 300 K. a. what is Ts, i in °C? b. what is Ts, o in °C?
The rear window of an automobile is defogged by passing warm air over its inner surface. If the warm air is at T∞,i=40°C and the corresponding convection coefficient is hi=30 W/m2·K, what are the inner and outer surface temperatures, in °C, of 4-mm-thick window glass, if the outside ambient air temperature is T∞,o= -27.5°C and the associated convection coefficient is ho=65 W/m2·K? Evaluate the properties of the glass at 300 K. a. what is the heat flux through the original walls in W/ m^2? b. what is the heat flux through the retrofitted walls in w /m^2?
You have a steel ball bearing with a diameter of 1.50 cm (k=40.0 W/(m-K); Density = 7800.0 kg/m^3; and specific heat = 600.0 J/(kg-K)). The ball bearing is initially at a uniform temperature of 1100 K and is then suddenly exposed to convection with a convection temperature of 320.0K and a convection coefficient of 25.0 W/(m2-K). Calculate the following: a) Calculate the time required to cool this ball bearing down to a temperature of 410.0 K. b) Calculate the amount of heat removed from the ball bearing during this cooling process.
20°C of a horizontal plate 16 cm long and 20 cm wide.Note that it hangs suspended in the air environment in .The plate is wrapped with 20W electrical heating elements.The heater is operating and the plate temperature is rising. ContinuousFind the temperature of the plate when the operating conditions are reached.The Spreading of the plate is 0.90 and the temperature of the surrounding surfaces is 17°C.is .
A mectal cylinder of 5 cm in diameter and initially at a temperature about 150 °C. the eylinder is suddenly immersed in liquid with temperature at 50 °C and heat transfer coeflicient about 2000 W/m.°C. Under typical operation conditions the center temperature and surface temperature are measured to be 110 °C and 90 °C after 1 minute, respectivielly. Calculate the thermal conductivity for this material.
A flat isothermal computer chip has square cross-section of 1 cm x 1 cm, and is mounted on a board that insulates the chip on its sides and bottom. The top surface is exposed to a flowing coolant at 10°C, and corresponding convection coefficient h = 1000 W/m2·K. In order for the computer chip to safely operate, its temperature cannot exceed 65°C. What is the maximum allowable chip power?
An electrical heater 114 mm long and 7 mm in diameter is inserted into a hole drilled normal to the surface of a large block of material having a thermal conductivity of 9 W/m · K. Estimate the temperature reached by the heater when dissipating 54 W with the surface of the block at a temperature of 27°C.
The door of a 1 m long by 27.5 cm wide oven is made up of 2 AISI 1010 carbon steel plates of identical thickness and an 8 mm thick mineral fiber board with resin binder (intermediate plate) . the composite plate considering the three plates is 5 cm. The temperature on the inner wall of the oven is 172 ° C and the surface temperature on the oven door (outer wall) is 35 ° C. The oven door is exposed in a room where the ambient air temperature is 30 ° C. Do the following: Estimate the convective heat transfer coefficient associated with ambient air.