Download presentation

Presentation is loading. Please wait.

Published byJakayla Longworth Modified over 3 years ago

1
Radiation Exchange between Surfaces: Participating Media Chapter 13 Section 13.5

2
General Considerations The medium separating surfaces of an enclosure may affect radiation at each surface through its ability to absorb, emit and/or scatter (redirect) radiation. Participating media may involve semitransparent solids and liquids, as well as polar gases such as CO 2, H 2 O(v), CH 4, and O 3. Radiation transport in participating media is a volumetric phenomenon, and for polar gases is confined to discrete wavelength bands. Beer’s law: A simple relation for predicting the exponential decay of radiation propagating through an absorbing medium. Transmissivity and absorptivity of medium of thickness L: Emissivity of medium. Assuming applicability of Kirchhoff’s law:

3
Gaseous Emission and Absorption Radiant Heat Flux from an Emitting/Absorbing Gas to an Adjoining Surface An approximate procedure involves use of a mean beam length, to apply emissivity data obtained for a hemispherical gas mass to other gas geometries. radius of a hemispherical gas mass whose emissivity, is equivalent to that for the geometry of interest. Emissivity data have been obtained for a hemispherical gas mass with radiating species of H 2 O (v) and/or CO 2 in a mixture with other nonradiating gases. Results depend on T g – the gas temperature p w, p c – the partial pressures of H 2 O (v) and CO 2 p – the total pressure of the mixture L – the radius of the hemisphere

4
Gaseous Emission and Absorption (cont) Fig. 13.20 Figs. 13.16, 13.17 Figs. 13.18, 13.19 correction factor for mutual absorption of radiation for H 2 O (v) and CO 2 For application to other gas geometries, replace L by L e. Rate of heat transfer to a surface of area A s due to emission from an adjoining gas is Net rate of radiation exchange between a black surface and an adjoining gas is Eq. (13.42) Eq. (13.41)

5
Problem 13.130 Problem 13.130: Heat recovery from flue gases to convert saturated water to saturated vapor.

6
Problem 13.130 (cont)

Similar presentations

Presentation is loading. Please wait....

OK

Temperature, Heat, and the First Law of Thermodynamics

Temperature, Heat, and the First Law of Thermodynamics

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Full ppt on electron beam machining metal Free ppt on brain machine interface definition Ppt on cognizant technology solutions Ppt on forest and wildlife resources in india Ppt on chapter 12 electricity and magnetism Ppt on off the job training methods Ppt on real numbers for class 9th maths Ppt on viruses and anti viruses for free Free ppt on planets in the solar system Download ppt on civil disobedience movement in united