Radiation Exchange EGR 4345 Heat Transfer Blackbody Radiation
Radiation Exchange EGR 4345 Heat Transfer
Blackbody Radiation Exchange
Blackbody Radiation Exchange Rate at which radiation leaves surface i and is intercepted by surface j For a black surface, Ji = Ebi Net radiative exchange
Blackbody Radiation Exchange Therefore Or Net radiation transfer from any surface in an enclosure of black surfaces
Net Radiation Exchange at a Surface in an Enclosure
Net Radiation Exchange at a Surface in an Enclosure l Assumptions – – – – Isothermal surfaces, Ti is known Uniform radiosity Uniform irradiation Opaque Diffuse Gray surface Medium in enclosure is nonparticipating
Net Radiation Exchange at a Surface in an Enclosure Determine the net rate at which radiation leaves surface i Where In terms of emissive power and absorbed radiation
Net Radiation Exchange at a Surface in an Enclosure For an opaque, diffuse, gray surface Solve for Gi and substitute into qi Or Driving Potential Surface Radiative Resistance
Net Radiation Exchange Between Surfaces in an Enclosure
Net Radiation Exchange Between Surfaces in an Enclosure Total rate at which radiation reaches surface i from all surfaces, including i Reciprocity Substituting in for Gi
Net Radiation Exchange Between Surfaces in an Enclosure Summation rule Therefore Or Use matrix operations to solve Space or Geometric Resistance
Net Radiation Exchange in a Two-Surface Enclosure Two diffuse, gray surfaces that form an enclosure
Net Radiation Exchange in a Two-Surface Enclosure Special equations General Equation
Radiation Shields General Equation Low emissivity increase resistance
Reradiating Surface Zero net radiation, qi = 0
Reradiating Surface
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