ENGR262 2022 Part B Q A2(b) (ENGR5002)

ENGR262 2022 Part B Q A2(b)Past paperOld spec ENGR2622:17 marks8 min

ENGR262 Separation Processes 2021-22 Part B Q A2[PARTIAL] Left out: (a)(i)-(iii) (18 marks), selection and design of solid-liquid extractors, are separation-process design and not on the current ENGR5002 syllabus.

Answer ALL parts (a) - (b). [Part (a), 18 marks on solid-liquid extraction, is omitted.]

Formulas you may need

Individual coefficients $N_A = k_G(p_{A,G} - p_{A,i}) = k_L(c_{A,i} - c_{A,L})$ (learn this)
Linear equilibrium (Henry) $p_A = Hc_A$ ; $p_A^* = Hc_{A,L}$ (learn this)
Result: $\dfrac{1}{K_G} = \dfrac{1}{k_G} + \dfrac{H}{k_L}$ (learn this)

(b)
For an absorption process where the equilibrium relationship is a straight line over the range of compositions considered, derive an expression relating the overall mass transfer coefficient, $K_G$ , to the individual mass transfer coefficients, $k_G$ and $k_L$ , using a suitably labelled driving force diagram. ( $K_G$ : overall mass transfer coefficient based on the gaseous phase; $k_L$ : individual (interfacial) mass transfer coefficient based on the liquid phase; $k_G$ : individual (interfacial) mass transfer coefficient based on the gaseous phase.)
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