Preface

In the landscape of today's energy conversion technologies, Organic Rankine Cycles (ORC) play a key role in the increase of the efficiency of energy-intensive industrial processes. Indeed, the adoption of ORC enables for the recovery of the available waste heat and its conversion to useful power. In particular, this technology is currently the most investigated one to convert the largest amount of available - and otherwise lost - energy: low-temperature waste heat. Many applications of ORC exist within the framework of waste heat recovery and this book aims to present some noteworthy examples of studied and available low- and high-power applications.

The crucial difference between ORCs lies in the working fluid they employ. The use of a specific working fluid imposes specific thermodynamic properties and, thus, establishes cycle layout and types of components. The choice of the working fluid mainly depends on the thermal characteristics of the available thermal source (temperature profile and heat grade) and should ideally result from an optimisation process. The current limit of applied optimisation processes mainly lies in the scarce flexibility and low accuracy of applied thermodynamic models and in the declared lack of experimental data to validate calculations. The first section of this book aims to provide researchers with proper tools to calculate and validate thermophysical properties of ORC working fluids. This section contains two chapters. The first one presents an accurate and predictive thermodynamic model to enable the reliable calculation of thermodynamic properties of thousands of pure fluids and their mixtures. The second chapter introduces a complete set of experimental techniques for the measurement of thermophysical properties of ORC fluids. The second section of the book introduces some theoretical and experimental studies of ORCs: a review of different supercritical ORC (Chapter 3), ORC for waste heat recovery from fossil-fired power plants (Chapter 4), and an experimental detailed characterization of a small-scale ORC of 3 kW operating with either pure fluids or mixtures (Chapter 5).

I wish to thank all the authors who contributed to the realisation of this book and the members of the IntechOpen publishing process staff for their fruitful and efficient cooperation.

> **Silvia Lasala** University of Lorraine, France

Section 1

Working Fluid

Characterization

**1**

Section 1
