Preface

The theoretical approach of this book is to develop a primary survey of basic thermodynamic concepts, allowing one to predict states of a fuel cell system, including its potential, temperature, pressure, volume, and moles. The specific topics explored include enthalpy, entropy, specific heat, Gibbs free energy, net output voltage irreversible losses in fuel cells, and fuel cell efficiency. Thermodynamics is the study of energy change from one state to another. The predictions that can be made using thermodynamic equations are essential for understanding fuel cell performance, as a fuel cell is an electrochemical device that converts the chemical energy of a fuel and an oxidant gas (air) into electrical energy.

Any system producing energy obeys the laws of thermodynamics. The amount of work/heat produced depends on thermodynamic values for reversible reactions, whereas for irreversible reactions overpotential is required to complete the work.

Herein is a review of modeling techniques for three types of fuel cells that are gaining industrial importance, namely, polymer electrolyte membrane (PEMFC), direct methanol (DMFC), and solid oxide (SOFC) fuel cells (FCs). The models presented are both multi-dimensional, suitable for investigating distributions, gradients, and inhomogeneities inside the cells, and zero-dimensional, which allows for fast analyses of overall performance and can be easily interfaced with or embedded in other numerical tools. The thermal dependence is considered in all models. Some special numerical approaches for facing specific problems are also presented.

In addition, the book presents research on the F-diagram method for the solar system via a thermosyphon circulation-diagram method based on the correlation of a number of simulations and computed non-dimensional variables. Modeling conditions varies in corresponding ranges of thermosyphon with double circuit circulation of the solar system. By means of the F-diagram method, environmental monthly temperature values with correction index have been computed, showing that the monthly average daily heating degree and direct solar radiation decrease according to weather conditions.

Starting from the equation of Einstein, the next chapter proposes a simple and fundamental presentation of fission and fusion principles, together with some of their applications, including in nuclear reactors and nuclear propulsion vessels and submarines. Fission and fusion are chosen as the most important forms of nuclear energy directly related with the equation of Einstein.

Renewable energies, which are by nature variable, are subject to both daily and/ or seasonal intermittencies. Electrochemical devices have been successful in proving their applicability in terms of energy storage (power to gas). Controlling in real time, predicting the performance is the advantage that electrochemical generators can offer.

Regarding how to build simple models of PEMFC for fast computation, Artificial Intelligence and mathematic tools can make smart grids smarter. The electrochemical

**II**

**Chapter 8 147**

**Chapter 9 169**

**Chapter 10 187**

**Chapter 11 227**

**Chapter 12 237**

Energy Storage in PCM Wall Used in Buildings' Application:

Water Desalination Using PCM to Store Solar Energy

*by Samadiy Murodjon, Xiaoping Yu, Mingli Li, Ji Duo* 

*by Majdi Hazami, Farah Mehdaoui, Hichem Taghouti, Marco Noro,* 

Lithium Recovery from Brines Including Seawater, Salt Lake Brine,

Fuel Cells: Alternative Energy Sources for Stationary, Mobile and

*by Irina Petreanu, Mirela Dragan and Silviu Laurentiu Badea*

Opportunity and Perspective

*by Paritosh Kulkarni*

*and Tianlong Deng*

Automotive Applications

*Renato Lazzarin and AmenAllah Guizani*

Underground Water and Geothermal Water

Fuel Cells as a Source of Green Energy *by Rabea Q. Nafil and Munaf S. Majeed* modeling can be coupled successfully with an AI approach if these models can be quickly computed with good numerical stability.

This book contains twelve chapters over two parts: "Theoretical Models" and "Applications."

The second section of the book includes an overview and general considerations about improving heat-engine performance via high-temperature recharge. Moreover, it investigates the efficiencies of heat-engine operation employing various numbers of heat reservoirs. It discusses operation with the work output of the heat engines sequestered, as well as with it being totally frictionally dissipated. We consider mainly heat engines whose efficiencies depend on ratios of a higher and lower temperature or on simple functions of such ratios, but also provide brief comments concerning more general cases.

Opportunity and perspective of energy storage in Phase Change Material (PCM) wall used in buildings' application are described further and the heat transfer phenomena and effect of it integrated inside a building on its indoor thermal comfort is investigated. A numerical investigation using specific software was also achieved to solve the energy and the exergy mathematic relations to evaluate the PCM wall performances by determining the melting phase proprieties during the charging and the discharging process. PCM is discussed as an application for water desalination to store solar energy. A possible solution to this problem is harnessing solar energy to engender thermal energy for solar distillation. Thus, solar distillation is one of the potential solutions to asses both the ever-increasing demands for clean water and for finding eco-friendly techniques to yield water. This analysis was undertaken to discover the possible utilization of PCM on solar distillation in a double slope solar still.

Another important subject covered in the book is lithium recovery from brines including seawater, salt lake brine, underground water, and geothermal water. This is very important due to the fact that the lithium market is expected to grow from 184,000 TPA of lithium carbonate to 534,000 TPA by 2025. To ensure the growing consumption of lithium, it is necessary to increase the production of lithium from different resources. Natural lithium resources mainly associate within granite pegmatite type deposits, salt lake brines, seawater, and geothermal water. Among these, the reserves of lithium resource in salt lake brine, seawater, and geothermal water are 70%–80% of the total, and are excellent raw materials for lithium extraction. Compared to the minerals, the extraction of lithium from water resources is promising because this aqueous lithium recovery is more abundant, more environmentally friendly, and cost-effective.

Last two chapters of the book examine fuel cells as alternative energy sources. Thus, they are expected to be a replacement for thermal engines and rechargeable batteries within the next few years as they are emission-free and not subject to Carnot restrictions. Fuel cells can be manufactured in different sizes depending on the amount of energy required. Herein, you will find a demonstration of the principle of work involved in fuel cells and their structural components as well as ideas to enhance output power.

Furthermore, the reader will find a classification and an overview of fuel cells, including working principles, equations of the governing reactions, and main applications. A brief exposure of thermodynamically and electrochemical theory

**V**

describe the functioning of fuel cells. Also, the book details PEMFC assembly, starting with the schematic presentation of the main components, the role of each component, specific materials and their requested properties, and the way of assembling the components into the device. Conclusions are presented, challenges related to reliability and cost are addressed, and targets for future development of

In this volume, scientists will find information starting from a theoretical approach of fuel cells to their use as alternative energy sources for stationary, mobile, and

**Petrică Vizureanu**

Romania

The "Gheorghe Asachi" Technical University Iaşi,

PEMFC for mobile and stationary applications are discussed.

automotive applications.

describe the functioning of fuel cells. Also, the book details PEMFC assembly, starting with the schematic presentation of the main components, the role of each component, specific materials and their requested properties, and the way of assembling the components into the device. Conclusions are presented, challenges related to reliability and cost are addressed, and targets for future development of PEMFC for mobile and stationary applications are discussed.

In this volume, scientists will find information starting from a theoretical approach of fuel cells to their use as alternative energy sources for stationary, mobile, and automotive applications.

> **Petrică Vizureanu** The "Gheorghe Asachi" Technical University Iaşi, Romania

**IV**

output power.

modeling can be coupled successfully with an AI approach if these models can be

This book contains twelve chapters over two parts: "Theoretical Models" and

The second section of the book includes an overview and general considerations about improving heat-engine performance via high-temperature recharge. Moreover, it investigates the efficiencies of heat-engine operation employing various numbers of heat reservoirs. It discusses operation with the work output of the heat engines sequestered, as well as with it being totally frictionally dissipated. We consider mainly heat engines whose efficiencies depend on ratios of a higher and lower temperature or on simple functions of such ratios, but also provide brief

Opportunity and perspective of energy storage in Phase Change Material (PCM) wall used in buildings' application are described further and the heat transfer phenomena and effect of it integrated inside a building on its indoor thermal comfort is investigated. A numerical investigation using specific software was also achieved to solve the energy and the exergy mathematic relations to evaluate the PCM wall performances by determining the melting phase proprieties during the charging and the discharging process. PCM is discussed as an application for water desalination to store solar energy. A possible solution to this problem is harnessing solar energy to engender thermal energy for solar distillation. Thus, solar distillation is one of the potential solutions to asses both the ever-increasing demands for clean water and for finding eco-friendly techniques to yield water. This analysis was undertaken to discover the possible utilization of PCM on solar

Another important subject covered in the book is lithium recovery from brines including seawater, salt lake brine, underground water, and geothermal water. This is very important due to the fact that the lithium market is expected to grow from 184,000 TPA of lithium carbonate to 534,000 TPA by 2025. To ensure the growing consumption of lithium, it is necessary to increase the production of lithium from different resources. Natural lithium resources mainly associate within granite pegmatite type deposits, salt lake brines, seawater, and geothermal water. Among these, the reserves of lithium resource in salt lake brine, seawater, and geothermal water are 70%–80% of the total, and are excellent raw materials for lithium extraction. Compared to the minerals, the extraction of lithium from water resources is promising because this aqueous lithium recovery is more abundant, more environ-

Last two chapters of the book examine fuel cells as alternative energy sources. Thus, they are expected to be a replacement for thermal engines and rechargeable batteries within the next few years as they are emission-free and not subject to Carnot restrictions. Fuel cells can be manufactured in different sizes depending on the amount of energy required. Herein, you will find a demonstration of the principle of work involved in fuel cells and their structural components as well as ideas to enhance

Furthermore, the reader will find a classification and an overview of fuel cells, including working principles, equations of the governing reactions, and main applications. A brief exposure of thermodynamically and electrochemical theory

quickly computed with good numerical stability.

comments concerning more general cases.

distillation in a double slope solar still.

mentally friendly, and cost-effective.

"Applications."

Section 1

Theoretical Models

**1**
