Question

The outer surface of a spacecraft in space has an emissivity of 0.6 and an absorptivity of 0.2 for solar radiation. If solar radiation is incident on the spacecraft at a rate of 1000 W/m2 , determine the surface temperature of the spacecraft when the radiation emitted equals the solar energy absorbed.

Answer 1

Answer:

$T_{surf} =$3.9°C

Explanation:

solution:

we express the surface temperature from the quality of the emitted and absorbed heat rates:

$Q_{abs} =Q_{em}$

$\alpha Q_{inc}=$εσA$T^{4} _{surf}$

$T_{surf} =$$\sqrt[4]{}$$\alpha$/εσ*$\frac{Q_{inc} }{A}$........................(1)

where

$\alpha$=0.2

ε=0.6

A=5.67*10^-8 W/m^2K^4

$Q_{inc}$= 1000 W/m^2

now putting these value in eq 1

$T_{surf} =$3.9°C