Question $3(40$ marks$)$

a$)$ A real surface is emitting radiation with wavelength ranging from $800nm$ to $3400nm$

at $1000K.$ You are told that emissivity $()$ is given as $0\mathrm{.}6$ at this range of emitted

radiation. Please calculate the energy flux emitted from the real surface as mentioned

above. Some conversion factors and constants are listed in APPENDIX. $[20$ marks$]$

b$)$ An open source of perfume $($composed of only molecule $A)$ is placed in the middle of

a large high$-$pressure chamber at $300K$ and $1\mathrm{.}52{10}^{6}Pa.$ You are told that the mole

fraction of $A$ in the gas phase inside the chamber is $0\mathrm{.}008.$ You are told that the air

velocity is $0\mathrm{.}24\frac{m}{s}.$ Please calculate the molar flux of $A$ in relative to other gas

molecules inside the chamber. Some conversion factors and constants are listed in

APPENDIX. $[20$ marks$]$