4.7 A single equilibrium stage in a distillation column is shown in Fig. E4.7. The model that describes this stage is dII dt = dH21 = dt Y1 = Lo+V2 (L1+ V₁) Loxo V2y2 (L1x1 + Viy1) ao+a1x1 + a2x² + a3x² Assume that the molar holdup H in the stage is constant and that constant molal overflow occurs. Thus, L₁ = Lo and V2 = V1. a. Linearize the resulting model and introduce deviation variables. b. For constant liquid and vapor flow rates, derive the four transfer functions relating outputs x₁ and y₁ to inputs x and y2. Place it in standard form. Lo V₁ Ут xo H L₁ V2 32 x1 کہ کہ Figure E4.7