2. Two very long concentric cylinders of diameters D=0.35 m and D2=0.5 m are maintained at uniform temperatures of T1 = 950 K and T2 = 500 K and have emissivities ɛ1 = 1 and ɛ2 = 0.55, respectively. Determine the net rate of radiation heat transfer between the two cylinders per unit length of the cylinders. What happens if the properties are just reversed.

2. Two very long concentric cylinders of diameters D=0.35 m and D2=0.5 m are maintained at uniform temperatures of T1 = 950 K and T2 = 500 K and have emissivities ɛ1 = 1 and ɛ2 = 0.55, respectively. Determine the net rate of radiation heat transfer between the two cylinders per unit length of the cylinders. What happens if the properties are just reversed.

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 1.24P: Two large parallel plates with surface conditions approximating those of a blackbody are maintained...

See similar textbooks

Similar questions

Determine the rate of radiant heat emission in watts per square meter from a blackbody at (a) 15C, (b) 600C, and (c) 5700C.
Two large parallel plates with surface conditions approximating those of a blackbody are maintained at 816C and 260C, respectively. Determine the rate of heat transfer by radiation between the plates in W/m2 and the radiative heat transfer coefficient in W/m2K.
1.28 The sun has a radius of and approximates a blackbody with a surface temperature of about 5800 K. Calculate the total rate of radiation from the sun and the emitted radiation flux per square meter of surface area.
Determine the total average hemispherical emissivity and the emissive power of a surface that has a spectral hemispherical emissivity of 0.8 at wavelengths less than 1.5m, 0.6 at wavelengths from 1.5to2.5m, and 0.4 at wavelengths longer than 2.5m. The surface temperature is 1111 K.
11.68 Two infinitely large, black, plane surfaces are 0.3 m apart, and the space between them is filled by an isothermal gas mixture at 811 K and atmospheric pressure. The gas mixture consists of by volume. If one of the surfaces is maintained at 278 K and the other at 1390 K, calculate (a) the effective emissivity of the gas at its temperature, (b) the effective absorptivity of the gas to radiation from the 1390 K surface, (c) the effective absorptivity of the gas to radiation from the 278 K surface, and (d) the net rate of heat transfer to the gas per square meter of surface area.
11.41 Determine the steady-state temperatures of two radiation shields placed in the evacuated space between two infinite planes at temperatures of 555 K and 278 K. The emissivity of all surfaces is 0.8.
2. A thin aluminum sheet with an emissivity of 0.15 on both sides is placed between two very large parallel plates, which are maintained at uniform temperatures T1 = 900 K and T2 = 650 K and have emissivities ?1 = 0.5 and ?2 = 0.8, respectively. Determine the net rate of radiation heat transfer between two plates per unit surface area of the plates and compare the result with that without the shield
Two very large parallel plates are kept at uniform temperatures T1=800 K and T2=500 K, and have emissivities ε1=0.2 y ε2=0.7, respectively, as shown in the figure. Determine the net rate of radiation heat transfer between the two surfaces per unit surface area of the plates.
A concentric cylinder with outer and inner radii of 8 cm and 6 cm, respectively, has length of 1 mwith emissivities of the inner and outer radii at 0.4 and 0.6, respectively. Determine the heattransfer from the outer cylinder to the inner cylinder if the inner and outer temperatures are400K and 600K, respectively.
Two concentric spheres of diameters D1 = 15 cm and D2 = 25 cm are separated by air at 1 atm pressure. The surface temperatures of the two spheres enclosing the air are T1 = 350 K and T2 = 275 K, respectively, and their emissivities are 0.75. Determine the rate of heat transfer from the inner sphere to the outer sphere by (a) natural convection and (b) radiation.
A thin aluminum sheet with an emissivity of 0.14 on both sides is placed between two very large parallel plates maintained at uniform temperatures of T1=720 K and T2=560 K. The emissivities of the plates are ɛ1=0.76 and ɛ2=0.85. Determine the net rate of radiation heat transfer between the two plates per unit surface area of the plates, and the temperature of the radiation shield in steady operation.