411-331 Heat and Mass Transport Processes 1

Credit Points

HECS Band

Coordinator

Prerequisites

411-102 Chemical Process Analysis, 411-201 Introduction to Transport Processes, 411-203 Fluid Mechanics, 411-204 Thermodynamics and Reactor Engineering 1 and 421-205 Engineering Analysis B or equivalent.

Corequisites

411-333 Thermodynamics and Reactor Engineering 2.

Semester

Contact

Subject Description

Students successfully completing this subject will be able to apply the principles of heat transfer to convective heat transfer problems, heat exchanger and evaporator designs, and to analyse and design equilibrium stage and continuous contactor separation operations including simple distillation, gas absorption and liquid extraction.

Heat Transport Processes Convection: Use of heat transfer correlations to predict coefficients; concept of an overall heat transfer coefficient, fouling factors; determination of the area required for a given heat duty. Free convection: Discussion and application of Grashof Number and other dimensionless groups. Heat exchanger design. Basics of condensation and boiling. Evaporation: Various evaporator types and their advantages and disadvantages (forced circulation, film types); multiple and single effects; backward and forward feed; boiling point elevation; apparent and actual heat transfer coefficients; thermal and mechanical recompression; evaporator energy balances.

Mass Transport Processes: Definition of separation processes, separating agents, separation factors, equilibrium and rate type processes, equilibrium stage, non-equilibrium performance. Unsteady state mass transfer and Fick's Second Law; prediction of diffusivity; dimensional analysis and equations of change for mass transfer. Equilibrium stage processes - Distillation: Single-stage separations, equilibrium flash, differential distillation; multistage separations, operating lines, reflux; binary distillation, varying reflux ratio, minimum reflux, total reflux, optimum reflux, feed plate location, side streams, open steam; tray efficiency via overall and Murphree efficiencies. Liquid Extraction: Applications of liquid extraction, liquid-liquid equilibria; single-stage extraction, choice of solvent/feed ratio; multistage cross-current extraction; continuous counter-current multistage extraction. Continuous Contact Operations - Gas Absorption: Basic mass transfer mechanism; material balances, co-current and countercurrent flow, limiting L/G ratio; multistage absorption and the absorption factor method; continuous contact, transfer units, height of a transfer unit, calculation of number of transfer units. Humidification and cooling tower height calculation.

Assessment

One examination not exceeding three hours at the end of the semester.