**Chapter 8 181**

Impregnation of Materials in Supercritical CO2 to Impart Various Functionalities *by Molla Tadesse Abate, Ada Ferri, Jinping Guan, Guoqiang Chen and Vincent Nierstrasz*

### **Chapter 9 195**

Foaming + Impregnation One-Step Process Using Supercritical CO2 *by Antonio Montes, Clara Pereyra and Enrique Martínez de la Ossa*

Preface

*Technologies*, which covers modern and advanced applications of supercritical fluids in various industries. The editorial team consists of top international experts, mainly from academia, but with engineering and technological experience, and representing the following countries: 1) Canada; 2) China; 3) Italy; 4) Japan; 5)

Using SuperCritical Fluids (SCFs) in various processes is not new, because Mother Nature has been processing minerals in aqueous solutions at critical and supercritical pressures for billions of years. In the late 1800s, scientists started to use this natural process in their laboratories to create various crystals. The first studies dedicated to the investigation of various properties and heat transfer in SCFs started possibly as early as the 1930s. It was found that heat transfer near a critical point was quite high, and this discovery was used in single-phase thermosyphons with an intermediate working fluid at the near-critical state. Therefore, solid knowledge of specifics of thermophysical properties and heat transfer is important for many

In the 1950s, the idea of using supercritical water was rather attractive for coalfired thermal power plants. At supercritical pressures, there is no liquid-vapour phase transition; therefore, there is no such phenomenon as critical heat flux or dry-out. Only within a certain range of parameters may a deterioration of heat transfer occur. The objective of operating "steam" generators at supercritical pressures was to increase the total efficiency of a power plant. Currently, the use of supercritical water in power-plant "steam" generators is the largest application of a

Also, at the end of the 1950s and the beginning of the 1960s, some studies were conducted to investigate the possibility of using SCFs in nuclear reactors. Several designs of nuclear reactors using water as the reactor coolant at supercritical pressures were developed in the USA and the former USSR. This idea was abandoned for

Currently, six concepts of nuclear-power reactors/nuclear power plants of the next generation – Generation-IV – were proposed, which will have thermal efficiencies comparable with those of modern thermal power plants. The SuperCritical Water-cooled Reactor (SCWR) is one of these six concepts under development in a number of countries. Analysis of Generation-IV concepts shows that SCFs, such as helium and water, will be used as reactor coolants, and SCFs such as helium, nitrogen (or mixture of nitrogen (80%) and helium (20%)), carbon dioxide, and water will be used as Working Fluids (WFs) in power Brayton and Rankine cycles.

However, there are other areas where SCFs are used or will be implemented in the

near future. The latest developments within these areas focus on:

IntechOpen presents a new technical book, *Advanced Supercritical Fluids* 

Romania; 6) Spain; 7) Sweden; and 8) USA.

applications of SCFs in industry.

fluid at supercritical pressures in industry.

almost 30 years but regained support in the 1990s.

The need for this book is based on the following rationale.
