Problem $6.$

Assume ethane combustion in air: $C_2{H}_6+\frac{7}{2}{O}_2=2C{O}_2+3H_{2}O$

a$.$ Find LFL$,$ UFL, and LOC $($limiting oxygen concentration$)$

b$.$ If LOL and UOL of ethane are $3\mathrm{.}0\%$ fuel in oxygen and $66\%$ fuel in oxygen, respectively, please find the stoichiometric line and draw a flammability diagram of ethane $($grid lines are provided in the next page$).$ Identify LOL, UFL, LFL$,$ UFL, LOC line, air$-$line, stoichiometric line, and flammability zone.

c$.$ If an ethane tank needs to be out of service, please calculate out of service fuel concentration $($OSFC$).$ Please redraw the flammability diagram of ethane and identify the out$-$of$-$service lines in the flammability diagram.

d$.$ After the maintenance of the ethane tank, we need to bring the tank into service. Please calculate the percentage of $N_2$ needs to be added prior to fill ethane to the tank. Please show the tank into service line in the flammability diagram.

$(5)$