Radiant energy transfer

If radiant energy transfer can be prevented, the following equation is used ... 

From here the water mixture rises through the water-wall tubes (generator tubes) that constitute the furnace membrane where steam is generated (primarily by radiant energy transfer). The steam-BW mixture is collected in top water-wall headers and conducted through risers (riser tubes) back to the top drum, where the saturated steam separates from the water at the steam-water interface. 

Designs include the once-through boiler, which can operate at sub-critical, critical, or supercritical pressures and at all commercial temperatures, and the radiant boiler, where heat absorption is largely by radiant energy transfer. 

A comparison of the transfer between two species in a vacuum and in the condensed phase reveals marked differences. Figure 5.4A depicts the energy levels of an electron in two species, where level eA in species A is occupied and level eB in species B is empty. If these levels had different energies, as indicated in the figure, then the non-radiant energy transfer would be... 

Although most analyses assume no radiant energy transfer, as will be shown subsequently, the addition of radiation poses no mathematical difficulty in the solution to the mass burning rate problem. 

The development of the relationships between scattered light and aerosols has stimulated the use of radiation transfer theory for remote sensing of particles in planetary atmospheres. Highly sophisticated experimental and theoretical techniques have emerged for the interpretation of observations of sunlight and artificial light sources in the earth s atmosphere. A description of their application depends on further development of the concepts of radiant energy transfer. 

Edwards, D. K., and K. E. Nelson, Rapid Calculation of Radiant Energy Transfer between Nongray Walls and Isothermal H20 and C02 Gas, J. Heat Transfer, vol. 84, p. 273, 1962. 

Total Exchange Areas When an enclosure contains reflective surface zones, allowance must be made for not only the radiant energy transferred directly between any two zones but also the additional transfer attendant to however many multiple reflections which occur among the intervening reflective surfaces. Under such circumstances,... 

In furnaces and other high-temperature equipment, where radiation is particularly important, the usual objective is to obtain a controlled rate of net heat exchange between one or more hot surfaces, called sources, and one or more cold surfaces, called sinks. In many cases the hot surface is a flame, but exchange of energy between surfaces is common, and a flame can be considered to be a special form of translucent surface. The following treatment is limited to the radiant-energy transfer between opaque surfaces in the absence of any absorbing medium between them. 

Here we will consider only the entropic contribution from the most common form of radiation, that which follows the Stefan-Boltzmann law. In this case, for a radiant energy transfer to a system of Qr the rate of entropy change is... 

To convert the radiant heat transfer coefficient to a contribution to the effective bed conductivity, the particle diameter must be included, because this affects the path length for radiant energy transfer. Radiation between particles and conduction through the solid are accounted for in the model of Schotte [32] ... 

The potential uses of this type of device are very broad, for exan le electrochromic windows, which control the radiant energy transfer in buildings and cars, inqtroving energy efficiency (1, 3), electrochromic rear-view minor systems in cars, flat panel displays, and smart paint The prospects for these l ds of applications have generated a high demand for new materials wifti inq)roved electrochromic response, thich is reflected in die increasing number of publications on the topic in recent years (4). 

In this equation, 1, is the mean free path of the photons. The radiant energy transfer is negligible in opaque materials because 1 0. It is significant in the case of silicates and single crystals at moderate temperature levels, where Ij reaches macroscopic dimensions. 

Supposing the temperatures of fhe opposite surfaces of a pore are Tj and T2, the radiant energy transfer between these surfaces is given by Equation 16.40. 

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