1

$n_{i,k}^{(F)}$ = mass or molar flow rate of species $i$ entering separator $k$ in feed stream (mass time^-1 or mol time^-1)

$n_{i,k}^{(1)}$ = mass or molar flow rate of species $i$ leaving separator $k$ in first product stream (mass time^-1 or mol time^-1)

$n_{i,k}^{(2)}$ = mass or molar flow rate of species $i$ leaving separator $k$ in second product stream (mass time^-1 or mol time^-1)

${\rm SF}_{i,k}$ = split fraction for species $i$ in separator $k$ (dimensionless)

${\rm SR}_{i,k}$ = split ratio for species $i$ in separator $k$ (dimensionless)

\begin{displaymath}

\tag{1.1}

{\rm SF}_{i,k} = n_{i,k}^{(1)}/n_{i,k}^{(F)}

\end{displaymath}

\begin{displaymath}

\tag{1.2}

{\rm SR}_{i,k} = n_{i,k}^{(1)}/n_{i,k}^{(2)} = {\rm SF}_{i,k}/(1-{\rm SF}_{i,k})

\end{displaymath}