EXAMPLE=wireConsider a long resistance wire of radius ₁ 0.2 cm and thermalconductivity k = 15 W/m . °C in which heat is generated uniformly asa result of resistance heating at a constant rate of g = 50 W/cm3. Thewire is embedded in a 0.5-cm-thick layer of ceramic whose thermalconductivity is k = 1.2 W/m °C. If the outer surface temperatureof the ceramic layer is measured to be Ts = 45°C, determine thetemperatures at the center of the resistance wire and the interface ofthe wire and the ceramic layer under steady conditions.ceramic17InterfaceMech. Eng. UOKWireCeramic layerT₁=45°C۳۰/۱۰/۲۰۱۳

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EXAMPLE Consider a long resistance wire of radius ₁ conductivity kwire =15 W/m °C in which heat is generated uniformly as a result of resistance heating at a constant rate of g = 50 W/cm3. The wire is embedded in a 0.5-cm-thick layer of ceramic whose thermal conductivity is kceramic = 1.2 W/m °C. If the outer surface temperature of the ceramic layer is measured to be Ts = 45°C, determine the temperatures at the center of the resistance wire and the interface of the wire and the ceramic layer under steady conditions. ) ។ . . Interface Mech. Eng. UOK Wire = 0.2 cm and thermal Ceramic layer T₁ = 45°C ۳۰/۱۰/۲۰۱۳

EXAMPLE Consider a long resistance wire of radius ₁ conductivity kwire =15 W/m °C in which heat is generated uniformly as a result of resistance heating at a constant rate of g = 50 W/cm3. The wire is embedded in a 0.5-cm-thick layer of ceramic whose thermal conductivity is kceramic = 1.2 W/m °C. If the outer surface temperature of the ceramic layer is measured to be Ts = 45°C, determine the temperatures at the center of the resistance wire and the interface of the wire and the ceramic layer under steady conditions. ) ។ . . Interface Mech. Eng. UOK Wire = 0.2 cm and thermal Ceramic layer T₁ = 45°C ۳۰/۱۰/۲۰۱۳

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.35P: A section of a composite wall with the dimensions shown below has uniform temperatures of 200C and...

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1.63 Liquid oxygen (LOX) for the space shuttle is stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. National Institute of Standards and Technology's Cryogenic Division; the superinsulation has an effective thermal conductivity of 0.00012 W/m K. If the outside temperature is on the average and the LOX has a heat of vaporization of 213 J/g, calculate the thickness of insulation required to keep the LOX evaporation rate below 200 g/h.
1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.4
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.
1.37 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.
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A section of a composite wall with the dimensions shown below has uniform temperatures of 200C and 50C over the left and right surfaces, respectively. If the thermal conductivities of the wall materials are: kA=70W/mK,kB=60W/mK, kC=40W/mK, and kD=20W/mK, determine the rate of heat transfer through this section of the wall and the temperatures at the interfaces.
A section of a composite wall with the dimensions shown below has uniform temperatures of 200C and 50C over the left and right surfaces, respectively. If the thermal conductivities of the wall materials are: kA=70W/mK,kB=60W/mK, kC=40W/mK, and kP=20W/mK, determine the rate of heat transfer through this section of the wall and the temperatures at the interfaces. Repeat Problem 1.34, including a contact resistance of 0.1 K/W at each of the interfaces.
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ähäi 100 Q1: Consider a long resistance wire of radius r1 = 0.3 cm and thermal conductivity kwire = %3D 17 W/m•°C in which heat is generated uniformly as a result of resistance heating at a constant rate of q = 100 W/cm3 (see Figure below). The wire is embedded in a 1-cm- thick layer of ceramic whose thermal conductivity is kceramic =1 W/m.°C. If the center temperature of the resistance wire is measured to be Tc= 705°C, determine the temperatures at the surface of ceramic and the interface of the wire and the ceramic layer under steady conditions.
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