Question

1. The radiator hemispherical emittance may be as high as 0.88 when the radiator is uncovered by a louver (refer to page 336 of the Spacecraft Thermal Control Handbook). \(\epsilon_{rad} = 0.88\) 2. When a louver is used and is closed, the emissivity can be considered as equal to the emissivity of the louver material, in this case Al, which we can set as 0.09, based on the value for sheet Al from Engineering Toolbox. \(\epsilon_{louver} = 0.09\) 3. When a louver is used and is open, the emissivity is a combination of the radiator and louver emissivities, depending on the relative visible surface area of each. \(\epsilon_{effective} = \epsilon_{louver} \frac{A_{louver}}{(A_{louver} + A_{visible\_radiator})} + \epsilon_{visible\_radiator} \frac{A_{visible\_radiator}}{(A_{louver} + A_{visible\_radiator})}\), where \(A_{louver} = \) area in grey, \(A_{visible\_radiator} = \) area in red, and \(A = A_{louver} + A_{visible\_radiator}\)

          1. The radiator hemispherical emittance may be as high as 0.88 when the radiator is uncovered by a louver (refer to page 336 of the Spacecraft Thermal Control Handbook).
\(\epsilon_{rad} = 0.88\)
2. When a louver is used and is closed, the emissivity can be considered as equal to the emissivity of the louver material, in this case Al, which we can set as 0.09, based on the value for sheet Al from Engineering Toolbox.
\(\epsilon_{louver} = 0.09\)
3. When a louver is used and is open, the emissivity is a combination of the radiator and louver emissivities, depending on the relative visible surface area of each.
\(\epsilon_{effective} = \epsilon_{louver} \frac{A_{louver}}{(A_{louver} + A_{visible\_radiator})} + \epsilon_{visible\_radiator} \frac{A_{visible\_radiator}}{(A_{louver} + A_{visible\_radiator})}\),
where \(A_{louver} = \) area in grey, \(A_{visible\_radiator} = \) area in red, and \(A = A_{louver} + A_{visible\_radiator}\)

1. The radiator hemispherical emittance may be as high as 0.88 when the radiator is uncovered by a louver (refer to page 336 of the Spacecraft Thermal Control Handbook).
ϵrad = 0.88
2. When a louver is used and is closed, the emissivity can be considered as equal to the emissivity of the louver material, in this case Al, which we can set as 0.09, based on the value for sheet Al from Engineering Toolbox.
ϵlouver = 0.09
3. When a louver is used and is open, the emissivity is a combination of the radiator and louver emissivities, depending on the relative visible surface area of each.
ϵeffective = ϵlouver(Alouver)/((Alouver + Avisible)) + ϵvisible(Avisible)/((Alouver + Avisible)),
where Alouver = area in grey, Avisible = area in red, and A = Alouver + Avisible

Added by Nerea R.

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