B) Answer the question shown in the image Consider a hollow sphere of internal radius 0.150 m and externalradius 0.600 m. The sphere is made of a material whose thermalconductivity is given by the following mathematical relationship: k = korWhere ko = 1.50 W / m²K and r is the radial distance measured fromthe center of the sphere. If the inner part of the sphere is at 20 ° C andthe outer part of the sphere is at 100 ° C. Calculate:B) The temperature at a distance from the center of 30 cm

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Consider a hollow sphere of internal radius 0.150 m and external radius 0.600 m. The sphere is made of a material whose thermal conductivity is given by the following mathematical relationship: k = k Where ko = 1.50 W / m²K and r is the radial distance measured from the center of the sphere. If the inner part of the sphere is at 20 ° C an 100

Consider a hollow sphere of internal radius 0.150 m and external radius 0.600 m. The sphere is made of a material whose thermal conductivity is given by the following mathematical relationship: k = k Where ko = 1.50 W / m²K and r is the radial distance measured from the center of the sphere. If the inner part of the sphere is at 20 ° C an 100

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 2.4P: A plane wall 15 cm thick has a thermal conductivity given by the relation k=2.0+0.0005T[W/mK] where...

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A plane wall 15 cm thick has a thermal conductivity given by the relation k=2.0+0.0005T[W/mK] where T is in kelvin. If one surface of this wall is maintained at 150C and the other at 50C, determine the rate of heat transfer per square meter. Sketch the temperature distribution through the wall.
1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.
1.29 A spherical interplanetary probe with a 30-cm diameter contains electronic equipment that dissipates 100 W. If the probe surface has an emissivity of 0.8, what is its surface temperature in outer space? State your assumptions in the calculations.
As a designer working for a major electric appliance manufacturer, you are required to estimate the amount of fiberglass insulation packing (k = 0.035 W/m K) that is needed for a kitchen oven shown in the figure below. The fiberglass layer is to be sandwiched between a 2-mm-thick aluminum cladding plate on the outside and a 5-mm-thick stainless steel plate on the inside that forms the core of the oven. The insulation thickness is such that the outside cladding temperature does not exceed 40C when the temperature at the inside surface of the oven is 300C. Also, the air temperature in the kitchen varies from 15Cto33C, and the average heat transfer coefficient between the outer surface of the oven and air is estimated to be 12.0W/m2K. Determine the thickness of the fiberglass insulation that is required for these conditions. What would be the outer surface temperature when the inside surface of the oven is at 475C?
The heat transfer coefficient between a surface and a liquid is 57 W/(m2K). How many watts per square meter will be transferred in this system if the temperature difference is 10C?
A pipe carrying superheated steam in a basement at 10C has a surface temperature of 150C. Heat loss from the pipe occurs by radiation (=0.6) and natural convection (hc=25W/m2K). Determine the percentage of the total heat loss by these two mechanisms.
A high-speed computer is located in a temperature-controlled room at 26C. When the machine is operating, its internal heat generation rate is estimated to be 800 W. The external surface temperature of the computer is to be maintained below 85C. The heat transfer coefficient for the surface of the computer is estimated to be 10W/m2K. What surface area would be necessary to assure safe operation of this machine? Comment on ways to reduce this area.
Using Table 1.4 as a guide, prepare a similar table showing the orders of magnitude of the thermal resistances of a unit area for convection between a surface and various fluids.
1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.
Discuss the modes of heat transfer that determine the equilibrium temperature of the space shuttle Endeavour when it is in orbit. What happens when it reenters the earths atmosphere?
GChoose the right answer 1. The temperature profile for steady hest conduction through a plane wall of constant thermal conductivity is a. logarithmic b. parabolic 2. A brick wall (k-0.75 W/mK ) transmits $02 of heat loss through another wall (k-0.25 W/mK, x-100 mm). If the temperature difference across both walls is the same, the thickness of the brick wall would be a.150 mm c. linear 6T b. 240 mm c. 300 mm d. 375 mm 3. The maximum temperature at the center of the solid sphere of radius R having heat generation q (W/m') is given by g'R +9R b. T, + 4k T+9R 6k d. T+9R 8k a. 2k C. 4. The internal thermal resistance of a solid can be ignored if the Biot number is less than a. 1 b. 0.5 c. 0.1 d. Fourier number 5. The ratio of heat transfer of a fin to the heat transfer without fin is referred to as a. fin resistance b. fin efficieney efin effectiveness d. fin conductance.
Consider a copper plate that has dimensions of 3 cm x 3 cm x 7 cm (length, width, and thickness, respectively). As shown in the following figure, the copper plate is exposed to a thermal energy source that puts out 126 J every second. The density of copper is 8,900 kg/m³. Assume there is no heat loss to the surrounding block. 126 J Copper Insulation Ⓡ What is the specific heat of copper (in J/(kg K))? J/(kg. K) What is the mass of the copper plate (in kg)? kg How much energy (in J) will be consumed during 11 seconds? J Determine the temperature rise (in K) in the plate after 11 seconds.