Mass and Heat Transfer II

Overview

Lectures (57 Hours):
Humidification (13 lectures + 3 tutorials):
 Fundamentals of humidification: basic definition; wet-bulb temperature; adiabatic saturation;
 Humidity data for air-water system: temperature-humidity chart; enthalpy-humidity; chart; Mixing of two streams of humid gas; addition of liquid or vapour to a gas.
 Methods for humidification and dehumidification and industrial applications;
�� Water cooling: fundamental principle; classification and structure; Design of cooling tower: heat and mass transfer: equilibrium and operating lines; stage calculations; Baker's graphical method; Numerical integration; Carey-Williamson method; packing height calculation; change in air condition; Temperature and humidity gradients in a water cooling tower; Evaluation of heat and mass transfer coefficients. Cooling tower operation and industrial applications.

Evaporation (6 lectures + 2 tutorials):
 Introduction to evaporation.
 Heat transfer in evaporators: heat transfer coefficient; boiling point rise (BPR); boiling at a submerged surface; forced convection boiling. Single-effect evaporators.
 Multiple-effect evaporators: general heat transfer; calculation and comparison of forward and backward feeds; effect of feed system on economy.
 Improved efficiency in evaporation.
 Evaporator operation.
 Equipment for evaporation: evaporator selection; evaporators with direct heating; natural circulation evaporators; forced circulation evaporators; film-type evaporators; plate-type evaporators; flash evaporators.

Multiple Component Distillation (15 Lectures + 3 Tutorials):
 Introduction
 Separation sequence; selection of the key components.
 Shortcut methods for multicomponent multistage separations:
 (1) Fenske equation and calculate the minimum equilibrium stages and product distribution;
 (2) Underwood equations for calculation of minimum reflux (Case I & II);
 (3) Gilliland correlation for determination of actual reflux ratio and equilibrium stages
 Equilibrium –Based methods for multicomponent distillation: Theoretical model for an equilibrium stage; MESH equations; Bubble-point (BP) method, Sum-rates (SR) method, and Newton-Raphson (NR) and Inside-Out methods for solving a tridiagonal-matrix equation; Equation-Tearing Procedures Using the Tridiagonal-Matrix Algorithm
 Inside-Out Methods

Leaching and washing (6 Lectures + 2 tutorials):
 Introduction of leaching and washing: general principle; industrial applications; factors influencing the rate of extraction; mass transfer in leaching operation;
 Equipment for leaching: extraction from different materials; batch extractors; continuous extractor; continuous, counter-current washing.
 Calculation of the number of stages: equilibrium-stage model for leaching and washing; McCabe-Smith Algebraic methods; variable underflow.
 Rate- based model for leaching: food processing; mineral processing.


Drying (6 lectures + 2 tutorials)
 Introduction to drying.
 Moisture-solid relationships; Mass and enthalpy balances.
 Types of moisture.
 Hygroscopicity.
 Drying rate curves; The constant drying rate period; Critical moisture content.
 Fall rate periods.
 Movement of moisture within a solid through drying.
 Total drying time.
 Rotary dryers; Drying equipment.

Crystallisation (4 lectures + 2 tutorials):
 Introduction of crystallization.
 Growth and properties of crystals: saturation, nucleation, growth of crystals, effect of impurities on crystal formation, effect of temperature on solubility, fractional crystallization, caking of crystals and yield of crystals.
 Crystallizers: batch and continuous crystallizers; industrial applications.

Membrane Processes (7 Lectures + 3 Tutorials):
 Introduction to membrane processes.
 Classification of membrane processes.
 Brief summary of membrane structure and types of membranes.
 Principle of operation of membrane separation units.
 Fundamental aspects of membrane processes; flux equations; mass transfer relationships; permeation rate; pressure drop relationships.
 Brief review of membrane applications.
 Electrically augmented membrane separation processes.
 The concept of concentration polarisation.
 The electro-kinetic flux equations.
 Electroceramic membranes and applications.

Detailed Syllabus – Tutorials/Seminars (17 Hours):
 Students are provided with tutorial and worked examples of the above lecture material. Tutorial classes are an integral element of the module.

 Humidification (3 tutorials), JAD
 Evaporation (2 tutorials), NG
 Multiple component distillation (3 tutorials), BX
 Leaching and washing (2 tutorials), NG
 Drying (2 tutorials), NG
 Crystallisation (2 tutorials), NG
 Membrane processes (3 tutorials), NG

Learning Objectives

On completion of this module a learner should be able to:
 understand the fundamentals and principles of heat and mass transfer and their applications (M1).
 develop competency in solving problems in humidification, drying, membrane, evaporation, distillation and crystallisation processes by applying fundamental concepts and principles of heat and mass transfer (M1, M2)
 develop the ability to apply fundamental heat and mass transfer theories to design units (M2)

The learning outcomes are aligned with the description in Engineering Council’s Accreditation of Higher Education Programmes V4.0 (AHEP 4)
 M1: Apply a comprehensive knowledge of mathematics, statistics, natural science and engineering principles to the solution of complex problems. Much of the knowledge will be at the forefront of the particular subject of study and informed by a critical awareness of new developments and the wider context of engineering.
 M2: Formulate and analyse complex problems to reach substantiated conclusions. This will involve evaluating available data using first principles of mathematics, statistics, natural science and engineering principles, and using engineering judgment to work with information that may be uncertain or incomplete, discussing the limitations of the techniques employed.

Skills

To develop skills of applying simultaneous heat and mass transfer principles in the design of cooling towers, membrane, dryers, distillation and evaporators.

Assessment

Assessment:
Examination 80%
Coursework 20%

Course Requirements:
Attendance at 80%
Examination Pass Mark at 40%
Coursework Pass Mark at 40%
Module Pass Mark at 40%

To gain modular credit a student must pass both the examination and all continual assessment elements of the course with minimum marks as shown below.  To gain modular credit a student must pass both the examination and all continual assessment elements of the course with minimum marks as shown above. Continual assessment is comprised of one class test or one assignment.