Energy and Mass Transfers E-Book

Abdelhanine Benallou

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 339

Veröffentlichungsjahr: 2018

Beschreibung

This is the first book of a series aiming at setting the basics for energy engineering. This book presents the fundamentals of heat and mass transfer with a step-by-step approach, based on material and energy balances. While the topic of heat and mass transfer is an old subject, the way the book introduces the concepts, linking them strongly to the real world and to the present concerns, is particular. The scope of the different developments keeps in mind a practical energy engineering view.

Leseprobe

Table of Contents

Cover

Preface

Introduction

I.1. Energy and mass transfers in industry

I.2. Practical examples

I.3. The role of the engineer

I.4. Management requirements

I.5. How may these requiremets be met?

I.6. The means at the engineer’s disposal

1 Basic Concepts and Balances

1.1. Thermal energy and the first law of thermodynamics

1.2. Thermal energy and the second law of thermodynamics

1.3. For an energy and mass accounting: balances

1.4. Fluxes and flux densities

1.5. Operating states

1.6. Transfer area

1.7. Driving potential difference

1.8. Exercises and solutions

1.9. Reading: seawater desalination

2 Mechanisms and Laws of Heat Transfer

2.1. Introduction

2.2. Mechanism and law of conduction

2.3. Mechanism and law of convection

2.4. Radiation transfer mechanism

2.5. Exercises and solutions

2.6. Reading: Joseph Fourier

3 Mass Transfer Mechanisms and Processes

3.1. Introduction

3.2. Classification of mass transfer mechanisms

3.3. Transfer mechanisms in single-phase systems

3.4. Mass transfer processes in single-phase media

3.5. Mechanisms and processes in two-phase media

3.6. Exercises and solutions

3.7. Reading: uranium enrichment

4 Dimensional Analysis

4.1. Introduction

4.2. Basic dimensions

4.3. Dimensions of derived magnitudes

4.4. Dimensional analysis of an expression

4.5. Unit systems and conversions

4.6. Dimensionless numbers

4.7. Developing correlations through dimensional analysis

4.8. Rayleigh’s method

4.9. Buckingham’s method

4.10. Exercises and solutions

4.11. Reading: Osborne Reynolds and Ludwig Prandtl

Appendix: Database

A.1. Introduction

A.2. Collision diameters and interaction energies

A.3. Densities

A.4. Heat capacities

A.5. Heat conductivities

A.6. Unit conversion tables

Bibliography

Index

End User License Agreement

List of Tables

1 Basic Concepts and Balances

Table 1.1.

Signs of

Table 1.2.

Variations in h(t)

Table 1.3.

Variations in T

2

as a function of time

2 Mechanisms and Laws of Heat Transfer

Table 2.1.

Experimental flux values (in W)

Table 2.2.

Flux ratios

3 Mass Transfer Mechanisms and Processes

Table 3.1.

Examples of collision diameters and interaction energies

Table 3.2.

Osmotic pressures of a sodium chloride solution

Table 3.3.

Rejection efficiencies of different solutes (cellulose acetate membrane with an acetyl content of 39.8%. Thickness: 0.16 μ. Pressure: 102 Atm)

Table 3.4.

D and σ (nonelectrolytes)

Table 3.5.

Parameters of commercial membranes

Table 3.6.

Electrical consumptions of desalination by electrodialysis

Table 3.7.

Calculating x

i+1

from x

i

Table 3.8.

Calculations implementation on a spreadsheet

Table 3.9.

Transfer areas of commercial packings

Table 3.10.

Determining the feeding plate via spreadsheet

Table 3.11.

Determining the number of stripping plates via spreadsheet

Table 3.12.

Implementing iterative calculations in a spreadsheet

Table 3.13.

Implementing calculations, in a spreadsheet, for plates 8

≤

j

≤

15

4 Dimensional Analysis

Table 4.1.

Basic dimensions

Table 4.2.

Dimensions of several derived magnitudes

Table 4.3.

Standard energy units

Table 4.4.

Units of heat conductivity

Table 4.5.

Units of the convection heat transfer coefficient,

h

Table 4.6.

Dimensionless numbers

Table 4.7.

Dimensions and units of α

Table 4.8.

Dimensions and units of β

Table 4.9.

Dimensions of D

1

and D

2

Table 4.10.

Technical data sheet

Appendix: Database

Table A.1.

Collision diameters and interaction energies

Table A.2.

Densities for metals and alloys (in kg/m

3

)

Table A.3.

Densities for construction materials (in kg/m

3

)

Table A.4.

Densities for construction materials (kg/m

3

)

Table A.5.

Densities according to manufacture (in kg/m

3

)

Table A.6.

Sensible heats for metals and alloys (in J kg-

1

°C)

Table A.7.

Sensible heats for certain construction materials (in J kg-

1

°C)

Table A.8.

Sensible heats of certain thermal insulation materials

Table A.9.

Heat conductivities of certain metals and alloys

Table A.10.

Heat conductivities of certain construction materials

Table A.11.

Conductivities of certain thermal insulation materials

Table A.12.

Unit conversion tables

List of Illustrations

Introduction

Figure I.1.

Onshore crude oil extraction (https://pixabay.com/fr/gréer-texas-591934/)

Figure I.2.

Offshore crude oil extraction (https://cdn.pixabay.com/photo/2017/04/22/16/06/rig-2251648_960_720.jpg)

Figure I.3.

Oil refinery (https://pixabay.com/fr/industrielle-raffinerie-pétrole-720710/)

Figure I.4.

Energy and mass transfers in an air-conditioning system

Figure I.5.

Meeting the requirements (https://pixabay.com/fr/ingénieur-caricature-dessin-animé-23810/)

Figure I.6.

Solving the equations (http://t0.gstatic.com/images?q=tbn:ANd9GcRy8RuH7MXiGBkSNzuiR2o0hgLAxtCqC6GHLLxeyNMf48a2ZrU7GDi7K56u)

1 Basic Concepts and Balances

Figure 1.1.

Balances on a system

Figure 1.2.

Inputs of mass into a reactor. For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 1.3.

Dryer

Figure 1.4.

Mixing tank

Figure 1.5.

Heating tank

Figure 1.6.

Stirred reactor

Figure 1.7.

Inputs of mass into a reactor

Figure 1.8.

Water supply reservoir

Figure 1.9.

Balance on an electric water heater

Figure 1.10.

Production of sweet juice

Figure 1.11.

Cross-section of a tubular exchanger

Figure 1.12.

Technical drawings of a pump spare part

Figure 1.13.

Exchange surface (hatched)

Figure 1.14.

Volume element of a metal bar

Figure 1.15.

Reverse-osmosis cell

Figure 1.16.

Stirred tank

Figure 1.17.

Printed circuit board comprising an energy dissipator

Figure 1.18.

Water-tower reservoir

Figure 1.19.

Sketch of th curve of h(t)

Figure 1.20.

Electric water heater

Figure 1.21.

Curve of T

2

(t)

Figure 1.22.

Heat exchanger. For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 1.23.

Stirred mixing tank

Figure 1.24.

Production of sweet juice

Figure 1.25.

Computer room

Figure 1.26.

Heat exchanger. For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 1.27.

Chemical reactor

2 Mechanisms and Laws of Heat Transfer

Figure 2.1.

Conduction transfer

Figure 2.2.

Volume element of the bar

Figure 2.3.

Heating a room

Figure 2.4.

Convection between a surface and a fluid

Figure 2.5.

Heating device with fan

Figure 2.6.

Convective motions created by differences in densities

Figure 2.7.

Radiation of a heated surface

Figure 2.8.

Two surfaces in arbitrary positions

Figure 2.9.

Radiation exchange between two black surfaces

Figure 2.10.

Convective flux

Figure 2.11.

Industrial furnace wall

Figure 2.12.

Black surface at temperature, T

Figure 2.13.

Parallel black surfaces

Figure 2.14.

Gray and black surfaces under total influence

Figure 2.15.

Non-parallel black surfaces

Figure 2.16.

Bar heated at one end

Figure 2.17.

Joseph Fourier

3 Mass Transfer Mechanisms and Processes

Figure 3.1.

Excitation of an atom by absorption of a photon

Figure 3.2.

Deexcitation of an atom by emission of a photon

Figure 3.3.

Osmosis mass transfer

Figure 3.4.

Osmotic pressure of a salt solution at different temperatures. For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 3.5.

Reverse-osmosis cell

Figure 3.6.

Determining the operating pressure

Figure 3.7.

Reverse osmosis cell in the form of a disc wrapped in membranes

Figure 3.8.

Reverse-osmosis module consisting of disc cells wrapped in membranes

Figure 3.9.

Reverse-osmosis system in parallel series

Figure 3.10.

Determining the operating pressure

Figure 3.11.

A dialysis cell

Figure 3.12.

Concentrations at the ends of a dialyzer

Figure 3.13.

Differences in concentrations for a batch dialyzer

Figure 3.14.

Multi-tube cell

Figure 3.15.

Staged cell

Figure 3.16.

Melting zone method

Figure 3.17.

Thermal diffusion in liquids

Figure 3.18.

Zippe centrifuge

Figure 3.19.

Schematic diagram of ultracentrifugation columns assembled in series/parallel

Figure 3.20.

Electromagnetic separation

Figure 3.21.

Schematic diagram of enrichment by flow separation

Figure 3.22.

Electrodialysis cells prior to passage of current (central compartment). For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 3.23.

Action of electric current on ions in electrodialysis cells. For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 3.24.

Obtaining purified solution and brine through electrodialysis. For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 3.25.

Electrodialysis by solar energy

Figure 3.26.

Liquid-vapor equilibrium curve for a binary mixture

Figure 3.27.

Equilibrium plate of a distillation column. For a color version of this figure, see www.iste.co.uk/benallou/energy1.zip

Figure 3.28.

Distillation column with reboiler and condenser

Figure 3.29.

Enriching section plate

Figure 3.30.

Enriching section plate, i

Figure 3.31.

Stripping plate, i

Figure 3.32.

Absorption column

Figure 3.33.

Solubility diagram

Figure 3.34.

Hydrogen absorption

Figure 3.35.

Hydrogen partial pressure

Figure 3.36.

Determining the fraction absorbed at equilibrium

Figure 3.37.

MPDx and MPDy

Figure 3.38.

Unpacked column and packed columns

Figure 3.39.

Examples of commercial packings

Figure 3.40.

Centrifuge

Figure 3.41.

Bank of centrifuge

Figure 3.42.

Osmotic separator

Figure 3.43.

Cellulose acetate membrane: operating characteristics

Figure 3.44.

Determining the operating pressure

Figure 3.45.

Membrane characteristics as a function of salinity

Figure 3.46.

Determining the operating pressure

Figure 3.47.

Desalination by electrodialysis

Figure 3.48.

Flash distiller

Figure 3.49.

Distilling a binary mixture

Figure 3.50.

Condenser x

1

2

Figure 3.51.

Enriching section plate, i

Figure 3.52.

Reboiler

Figure 3.53.

Ethanol distillation column

Figure 3.54.

Distillation column available

Figure 3.55.

Details of the condenser

Figure 3.56.

Balance on the enriching section plate, i

Figure 3.57.

Balance on stripping section plate, j

Figure 3.58.

Balance on the reboiler

4 Dimensional Analysis

Figure 4.1.

Magnitude depending on a single variable

Figure 4.2(a).

Magnitude G depending on two variables, v1 and v2 (v2 constant)

Figure 4.2(b).

Magnitude G depending on two variables, v1 and v2 (v1 constant)

Figure 4.3.

Sweet-juice preparation tank

Figure 4.4.

Feed reservoir

Figure 4.5.

Stirred tank with a steam jacket

Figure 4.6.

Staged reverse-osmosis unit

Figure 4.7.

Osborne Reynolds

Figure 4.8.

Ludwig Prandtl

Guide

Cover

Table of Contents

Begin Reading

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G1

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e1

Energy Engineering Set

coordinated by Abdelhanine Benallou

Volume 1

Energy and Mass Transfers

Balance Sheet Approach and Basic Concepts

Abdelhanine Benallou

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd

27-37 St George’s Road

London SW19 4EU

UK

www.iste.co.uk

John Wiley & Sons, Inc.

111 River Street

Hoboken, NJ 07030

USA

www.wiley.com

© ISTE Ltd 2018

The rights of Abdelhanine Benallou to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Control Number: 2018938268

British Library Cataloguing-in-Publication Data

A CIP record for this book is available from the British Library

ISBN 978-1-78630-274-8

Preface

“Good things arising from prosperity are desired, but good things stemming from adversity are admired”

Seneca, stoic philosopher, 4 BC. - 65 AD.

For several years, I have cherished the wish of devoting enough time to the writing of a series of books on energy engineering. The reason is simple: for having practiced for years teaching as well as consulting in different areas ranging from energy planning to rational use of energy and renewable energies, I have always noted the lack of formal documentation in these fields to constitute a complete and coherent source of reference, both as a tool for teaching to be used by engineering professors and as a source of information summarizing, for engineering students and practicing engineers, the basic principles and the founding mechanisms of energy and mass transfers leading to calculation methods and design techniques.

But between the teaching and research tasks (first as a teaching assistant at the University of California and later as a professor at the École des mines de Rabat, Morocco) and the consulting and management endeavors conducted in the private and in the public sectors, this wish remained for more than twenty years in my long list of priorities, without having the possibility to make its way up to the top. Only providence was able to unleash the constraints and provide enough time to achieve a lifetime objective.

This led to a series consisting of nine volumes:

–

Volume 1:

Energy and Mass Transfers;

–

Volume 2:

Energy Transfers by Conduction;

–

Volume 3:

Energy Transfers by Convection;

–

Volume 4:

Energy Transfers by Radiation;

–

Volume 5:

Mass Transfers and Physical Data Estimation;

–

Volume 6:

Design and Calculation of Heat Exchanges;

–

Volume 7:

Solar Thermal Engineering;

–

Volume 8:

Solar Photovoltaic Energy Engineering;

–

Volume 9:

Rational Energy Use Engineering.

The present book is the first volume of this series. It groups the basic concepts and the fundamental mechanisms governing heat and mass transfers. It aims to meet the requirements of clarity in the presentation of the fundamental theories in the perspective of enabling students to fully understand the basic principles, before moving on to the details of equipment design and sizing.

This book is therefore introductory and simple. It is intended to expose the mechanisms governing heat and matter transfers within the same system or between two or more systems.

As we will see throughout this book, applications of these concepts and principles are multiple: they are considered essential in sizing techniques of industrial equipment of different kinds. They also have become paramount in the design of ‘smart buildings’ and in the development of mathematical models to perform predictions of climate change through the greenhouse effect or the thinning of the ozone layer. In addition, these concepts form the basis of engineering calculation methods of industrial equipment, which must satisfy, from now on, minimum energy consumption constraints.

This introductory book constitutes a clear and solid foundation, on which a robust construction of energy engineering techniques can be undertaken.

We have consequently used simple and practical ways to explain complicated principles. We have also given considerable importance throughout the document to integrating as many practical examples as illustrations, to allow a better visualization of the phenomena and to help make applications of the different equations, student friendly, positive, tangible and concrete.

Abdelhanine BENALLOUApril 2018

IntroductionTransfer Techniques: What Role for the Engineer?

I.1. Energy and mass transfers in industry

Within different industries, products are often elaborated through the transformation of several inputs. In most cases, various manipulations of the inputs are involved before arriving at the desired end products. Through these manipulations, the initial inputs undergo multiple transformations during which they are heated, cooled or even consumed in order to give rise to new components.

It is obvious that heating or cooling will require energy exchange between the components of the process considered. In the same way, generation of new products implies chemical reactions between the inputs.

Thus, during the course of these transformations, several types of transfer take place between the inputs. Energy and mass transfers are the most significant. Whilst mass transfers are mainly conducted to purify or to elaborate products, energy transfers are intended to provide the calories necessary for heating, as well as cooling or air conditioning, delivering the heat for an endothermic chemical reaction, or cooling a nuclear reactor, etc.

I.2. Practical examples

I.2.1.Oil extraction and refining

We already know that in order to manufacture the different fuels that we use for our convenience (gasoline or kerosene, for example), we first have to proceed with the extraction of oil, onshore or offshore.

Figure I.1.Onshore crude oil extraction (https://pixabay.com/fr/gréer-texas-591934/)

Figure I.2.Offshore crude oil extraction (https://cdn.pixabay.com/photo/2017/04/22/16/06/rig-2251648_960_720.jpg)

The crude oil produced in this way is then transferred to refineries, where it will be treated to extract various fuels.

Figure I.3.Oil refinery (https://pixabay.com/fr/industrielle-raffinerie-pétrole-720710/)

Among the products extracted, we find gasoline to keep our car engines running, kerosene to fuel aircraft reactors, fuel oil to power the boilers of thermal powerstations, etc.

These different treatments require multiple mass and heat transfers before resulting in the desired end products.

I.2.2.Air-conditioning a room

Proper operation of data centers or sophisticated electronic devices very often requires an environment whereby temperature and humidity are controlled, in order to ensure optimal operating conditions and avoid any damage to their components.

Figure I.4 shows a typical data center room with an air-conditioning system designed to maintain temperature at T* and humidity at h*, regardless of eventual variations in the surrounding conditions, such as the outside temperature, the sun shining through the windows, the opening and closing of doors, the presence of individuals inside the room, etc.

Figure I.4.Energy and mass transfers in an air-conditioning system

The maintaining of constant temperature and humidity inside the data center requires multiple energy and mass transfers to be operated by the air-conditioning system: Energy transfers aim to maintain the temperature around T* while mass exchange stabilizes the humidity around h*.

I.3. The role of the engineer

Whether for the examples presented in section I.2 or for more general cases of industrial production processes, the engineer’s role will be different depending on the type of task considered: designing a new plant or acting on existing equipment. For the first type of task, the role of the engineer is to design and build the devices that will make it possible to carry out the various transformations and lead to the end products or reach the objectives sought.

If we consider an existing production unit where equipment is already on site, the engineer’s role is to define and ensure optimal operating conditions and parameters, i.e. those which will produce the best results.

In order to do so, it will first be necessary to carry out a detailed analysis of the equipment involved and its operating conditions. This diagnosis will be necessary in order to check whether the different devices are running in the best possible manner or whether their operation can be improved. In the latter case, the role of the engineer is to define possible improvements and to size the equipment or the changes defined by the potential improvement.

Moreover, whether they are designing new production equipment or conducting a diagnosis in the perspective of defining optimal operating conditions of an existing installation, engineers must always keep in mind the cost imperatives. Indeed, the various studies, diagnoses, analyses and calculations must be approached in the most economical manner possible, since the ultimate goal of any industrial operation, beyond product manufacturing, is to make a profit.

Thus, the role of the engineer is often twofold:

–

to identify and size the devices needed and define their optimal operating conditions

in order to carry out the necessary transformations and thus to manufacture the desired end product;

– to ensure the best economical operation leading to competitive

production costs

.

The different fields of engineering (electrotechnics, fluid mechanics, electronics, productics, energy, etc.) each respectively define the relevant equipment design and sizing techniques. However, whatever the field of engineering concerned, it will be essential to understand the fundamental mechanisms that govern the different transformations involved, in order to be able to perform optimal design and sizing of the necessary equipment.

Knowledge of the mechanisms underlying the different production processes is especially necessary in order to be able to translate the required transformations into equations. In fact, it is based on these equations that equipment design techniques are developed.

In addition, in order to achieve competitive end product prices, it will be necessary to identify the impacts of the selected processes on production costs. To consider only energy inputs for example, it is readily known that high energy consumption will lead to additional production costs and that, conversely, minimizing energy consumption results in squeezing costs.

An example of this type of optimization is presented when reduction of energy losses through the walls of buildings is considered (see Volume 2, Chapter 4 of this series), or through the envelopes of furnaces or industrial installations (see Volume 2, Chapter 3 of this series).

This type of analysis can also be applied to mass transfer. Indeed, low mass transfer rates will be reflected in high cost prices, while improving the efficiency of a given mass transfer process will lead to higher outputs, and consequently to a reduction in production costs.

I.4. Management requirements

Thus, the engineer is often asked to respond to various requirements of his management which are, in most cases, expressed as follows: how to minimize the operating budget of a manufacturing unit, whilst observing basic safety rules and international regulations in force.

Indeed, the management determines the objectives for the engineer in technical terms (a given production level needs to be ensured), but also in financial (minimal production cost) and regulatory terms (safety and production standards must be adhered to).

An engineer is the refore faced with a multidimensional problem.

I.5. How may these requiremets be met?

At a technical level, the engineer must be in a position to design the equipment that will be capable of ensuring the desired transformation and therefore lead to the end products sought. To achieve this, it will be necessary to translate the sought transform mations into equations. Thus, knowledge of the different mass and energy transfer mechanisms and the establishment of the equations that govern them will be necessary.

Likewise, at the financial and regulatory levels, the production costs and the constraints imposed by safety rule and regulatons (standards) must be taken into consideration.

Figure I.5.Meeting the requirements (https://pixabay.com/fr/ingénieur-caricature-dessin-animé-23810/)

Thus, to satisfactorily respond to management requests, an engineer must firstly be in a position to translate the processes into equations, then incorporate the cost, regulatory and safety considerations into these equations. He/She will then hope to solve the equations thus developed.

I.6. The means at the engineer’s disposal

In order to solve the set of equations that arise from the mathematical translation of his management requests, the engineer can use several means available to him:

– the arsenal constituted by all of the theories learned in the different fields of engineering: fluid mechanics, optimization, applied mathematics, etc. This book deals with one of these theoretical bases of engineering techniques;

– all of the computing means available in order to solve the equations: computers, software packages, etc.

Figure I.6.Solving the equations (http://t0.gstatic.com/images?q=tbn:ANd9GcRy8RuH7MXiGBkSNzuiR2o0hgLAxtCqC6GHLLxeyNMf48a2ZrU7GDi7K56u)

As such, the purpose of this book is to explain the mechanisms that govern mass and energy transfers. The perspective is to establish the equations which govern their underlying processes in a way which will make design and optimization tasks possible.

In addition, many possible practical applications of these equations are presented using concrete examples and, where useful, the resulting economical optimization issues are also discussed.

As we will see in detail in Chapter 1, in order to be able to carry out analyses on manufacturing processes or on physical systems, certain knowledge of the quantities of energy and mass transferred is essential. It will thus be necessary to establish certain rules of accounting for mass and energy exchanges. Indeed, in the same way that an accountant is led to monitor expenditure and revenue in order to draw up a company’s financial balance sheets, the engineer will need to monitor the mass and energy inputs and outputs within a given system in order to draw up the mass and energy balances for the installation concerned. We will see that this notion of ‘balance sheet’ is extremely important in industrial process analysis methodology. We will also see that it is thanks to this balance-sheet approach that we can establish the equations that govern a given transformation.

Chapter 1 also introduces a number of important concepts, such as transfer area and driving potential difference (DPD) that enable a simple formalization of the expressions of mass and energy flows.

Chapter 2 presents the mechanisms of heat transfer, as well as the basic laws governing energy flows in different circumstances. This summary presentation of the various heat transfer laws permits, from the outset, the determination of heat fluxes in the simplest cases, without having to wait for the more elaborated developments detailed in Volumes 2 to 4 of this series.

The mechanisms for mass transfer, meanwhile, are summarized in Chapter 3, where the concepts underlying the flow or the movement of matter are depicted at the microscopic level. This chapter also presents several mass transfer techniques such as reverse osmosis, centrifugation, electrodialysis, distillation or absorption.

In Chapter 4, a formalization of the dimensional analysis technique is presented. The importance of this technique is underlined, first as a powerful tool for verifying the validity of equations or for defining homogeneous unit systems, secondly as a basic technique to be used in Volume 3 of this series to study energy transfer by convection.

Moreover, throughout this series, a database of physical parameters and constants is constructed in order to gather all of the data needed for energy engineering calculations. This volume presents the basic data encountered in the initial developments, as well as a unit conversion table.

It should be noted that the database core presented in the appendix constitutes the seed that will lead, over the course of the different volumes, to the global database. The latter will constitute a quick reference tool for the student to consult in order to resolve the problems posed in the different volumes of the series.

Finally, this book aims to establish, in a clear and solid manner, the fundamental principles and concepts that govern energy and mass transfers in industrial processes. Throughout its various chapters, we have been keen to present and explain the basic theories underlying these transfers, without seeking to introduce the details of the in-depth studies, which are the subject of the subsequent volumes in the series.

We also felt it was important to integrate many practical examples as illustrations, in order to help visualize the phenomena, and to make the applications of the different equations student-friendly, more tangible and concrete.

Moreover, in order to allow the student to implement the new concepts as rapidly as possible, a series of illustrative exercises is presented at the end of each chapter. These exercises have been designed to correspond, as much as possible, to real situations from industrial practise or everyday life. In presenting the solutions retained for each of the exercises, we voluntarily adopted a level of detail that leaves no room for hesitation and encourages full implementation of the solutions; that is, by completing and presenting all of the details of the numerical applications.

Indeed, it is widely known that engineering students are generally reluctant to perform or complete numerical calculations. We have consequently given particular importance to the numerical applications presented in the examples.

We hope that this book will accomplish its initial mission: to provide a simple learning tool that will assist engineering students in their understanding of the basic principles of mass and heat transfer. We voluntarily chose a simple way of presenting the different principles and mechanisms by deferring the more comprehensive and detailed studies to a later stage.