Preface

Thermal energy is present in all aspects of our lives. We experience heat transfer daily when, for example, cooking or taking food out of the fridge, using a vehicle, or turning on the heating or air-conditioning system in our office. Sometimes this thermal management is not evident, but it is essential for our comfort and lifestyle. In addition, heat transfer is of vital importance in all electric power plants. Whether some fuel is burned to obtain steam or whether we want to maintain a solar panel temperature to a certain level, proper management of thermal energy is crucial to the operation of the system.

Nowadays it is even more important to control thermal transfer perfectly when designing renewable energy systems where every unit of energy requires use or when installing an efficiency measure in a process to prevent thermal losses.

Thermal energy analysis is a complex task that usually requires the use of large theoretical equations and mathematical models that can predict the behaviour of a certain system. Many approaches can be followed to study all these phenomena. Some of them involve experimental developments that include the building of test benches, rigs, and real systems to replicate the process to be studied. Others are computational models that predict the performance of the system and can be used as optimization tools when designing devices.

This book includes a large compilation of those different approaches and serves as an example of how heat transfer problems can be analysed. It is divided into the following five sections:


I hope this book will help engineers, researchers, and scientists to understand thermal processes better and teach them how to address heat transfer problems. I also hope it serves as an inspiration for the development of further work.

I would like to express my gratitude to all the authors who have contributed to this book. I am sure their knowledge and expertise have improved the quality of this text. Lastly, I give thanks to IntechOpen Author Service Manager Dolores Kuzelj, whose assistance and patience have been crucial to the success of this project.

> **Dr. Miguel Araiz Vega** Department of Engineering, Smart Cities Institute, Public University of Navarre, Pamplona, Spain

> > Section 1

Introduction

Section 1 Introduction

**3**

**Chapter 1**

Transfer

*Miguel Araiz*

**1. Introduction**

losses [7, 8].

**2. Heat transfer analysis**

understand all these processes [9].

**2.1 Computational simulations**

heat transfer in any application.

Introductory Chapter: Heat

Heat transfer is the field in Thermodynamics in charge of the study of the generation, conversion, exchange and use of energy in form of heat (thermal energy) between different systems. Heat can be transferred using several mechanisms such as conduction, convection, and radiation. The proper understanding of these modes of heat transfer leads to a successful design of any device in which thermal energy is involved. That is why it is so important to study and to analyze

Thermal energy is present in any aspect of our lives. We can daily experiment heat transfer phenomena at home, when cooking or taking food out of the fridge [1], when using a vehicle to go to work [2] or turning the heating or air-conditioning system on in our office [3]. Sometimes this thermal management is not evident but it is essential for our comfort and lifestyle [4]. Besides, heat transfer is of vital importance in all the electric power plants. Whether some fuel is being burnt to get steam or if we want to maintain a PV panel temperature to a certain level, again a proper management of thermal energy is crucial to the operation of the system [5, 6]. And nowadays it is even more important to perfectly control thermal transfer when designing renewable energy systems where every unit of energy requires to be used; or when installing an efficiency measure in a process to prevent thermal

Thermal energy analysis is a complex task that usually requires the use of large theoretical equations and mathematical models that can predict the behavior of a certain system. It is not easy to simplify natural or forced convection, phase change phenomena, or radiation heat transfer, considering their interactions with other parts of the system under study. Therefore, most of the engineers and researchers in the thermal field turn to computational models and test benches that help them

A very common approach to heat transfer study is to develop a computational model making several assumptions prior to the simulations. These models use thermodynamic equations and energy balances to represent what we can expect to happen in real conditions. These computational tools are really useful since they allow us to perform tons of simulations and analyze many cases in a cost-effective manner. You can use them to optimize a certain design and be sure that it will work
