23-Chem-A3 Heat and Mass Transfer: December 2013

National Exams — December 2013 — 04-Chem-A3 Mass Transfer Operations. Three-hour, open-book exam; any non-communicating calculator permitted. Format: six questions in two parts — answer two of Q1–Q3 (Part A) and two of Q4–Q6 (Part B); four questions of equal value constitute a complete paper. All six are solved below for completeness. Property data (diffusivities, vapour pressures, psychrometric enthalpies) are stated in each Given block; the psychrometric appendix supplied with the exam furnishes the saturated-air enthalpies used in Q5.

Reference texts: Geankoplis, Transport Processes and Separation Process Principles (4th ed., Prentice Hall) — molecular diffusion, unsteady-state diffusion, absorption and humidification; Treybal, Mass-Transfer Operations (3rd ed., McGraw-Hill) — Stefan diffusion, gas absorption, cooling-tower design; Welty, Wicks, Wilson & Rorrer, Fundamentals of Momentum, Heat and Mass Transfer (boundary-layer mass transfer); supporting property/psychrometric data from Perry's Chemical Engineers' Handbook (9th ed.).