Preface

While great efforts are being made to reduce energy consumption, the world needs to further explore renewables like solar, wind, hydropower, geothermal, and even sustainable nuclear energy. However, due to high capital cost, these alternatives have not found wide application in industry. However, this is beginning to change with the emergence of scientific evidence that alternative sources of energy can help achieve sustainability in energy recovery (ER) processes. The case for other industries will follow the same argument especially since most of these heavy industries require enormous amounts of energy, derivable from fossil fuels oil and gas due to their resilience in offering likewise enormous motive power twenty-four hours a day. This book discusses sustainable ER development in our deliberate pursuit of energy independence in a world bedeviled by the ill effects of environmental degradation. In a world that needs energy, we should embrace the practice of utilizing ER systems in all their forms, natural and technological.

This book investigates ER in large industries and utilities throughout the world. In all aspects of heat exchanges, energy recoveries are involved, but the problem in all energy recoveries is that the percentage of energy recovered is not related to the total energy consumption in industry, organization, or household. It should be noted that among other objectives of studying ER one should take cognizance of the fact the recovered energy has these attributes: (1) it is quality energy because it is immediately useful without further processing depending on the point of collection, either through recuperators or economizers, whereby utilization is in preheating incoming air to a combustion chamber/ furnaces or in an AC/refrigeration system, which depends on the outside; (2) it becomes available energy, serving the purpose of extracting tangible heat (enthalpy) from the air, which is a two-component system for immediate use in effecting cooling on the area. The explanation here is that the wet air that contains water vapor after reaching its saturation vapor pressure undergoes the process of evaporation thereby cooling that point.

Chapter 1 pays special attention to the magnetocaloric effect (MCE) that is observed when magnetic systems are subjected to an external magnetic field. The authors use the derivative of Gibbs free energy to estimate the magnetic entropy change and the mean-field theory to sort out the spontaneous magnetization from the dependence of magnetic entropy change on magnetization vs. Gd systems. The obtained spontaneous magnetization values are in good agreement with those found from the extrapolation from the Arrott plots (H/M vs. M2). An excellent agreement has been found between the values estimated by Landau's theory and those obtained using the classical Maxwell relation. The intermetallic Gd3Ni2 and Gd3CoNi exhibit a large MCE manifested with a high entropic peak that can boost refrigerant capacity, which makes these alloys good candidates for magnetic refrigerators.

A micro-thermoelectric generator (TEG) possesses great potential for powering wireless Internet of Things (IoT) sensing systems due to its capability of harvesting thermal energy into usable electricity. Chapter 2 reviews the progress in recent studies on micro-TEG from material synthesis to device fabrication. Thermoelectric materials are synthesized by the electrochemical deposition method. Three kinds of high-performance thermoelectric materials, including thick bulk-like thermoelectric material, Pt nanoparticles embedded in a thermoelectric material, and Ni-doped thermoelectric material, are presented.

The growth of the semiconductor market and advancement of manufacturing technology have led to an increase in wafer size and highly integrated semiconductor devices. The temperature of the supplied cooling medium from the chiller that removes the heat produced in the semiconductor manufacturing process is required to be at a lower level because of the high integration. The Joule-Thomson cooling cycle, which uses a Mixed Refrigerant (MR) to produce the cooling medium at a level of −100°C required for the semiconductor process, has recently gained attention. Chapter 3 discusses this in detail. When an MR is used, the chiller's performance is heavily influenced by the composition and proportions of the refrigerant charged to the chiller system. Therefore, this chapter introduces a cooling cycle that uses an MR to achieve the required low temperature of −100°C in the semiconductor manufacturing process and provides the results.

Chapter 4 explains that the solar furnace supply doesn't make changes inside a material by using electric energy produced by a photovoltaic system that converts solar energy. The performances of a solar furnace used in various applications from industry are influenced by various factors. One of these factors imposes the acquisition of certain large densities of the radiant power and requires a geometric form of the concentrator. The most important research is made on the behavior of some metallic alloys at elevated temperatures, on some purifying materials, and on the achievement of some chemical synthesis. For manufacturing electrothermal furnaces, a series of specific materials are used that are necessary for the achievement of the furnace chamber (e.g., heating elements and measurement systems of the temperature).

Since the world is gradually drifting toward sustainable development, renewable energy technologies are gaining traction and gasification technology is one of many renewable energy technologies that have gained popularity in recent times. Gasification technology is one of three main (combustion and pyrolysis) thermochemical conversion pathways that can be used to recover energy from biomass materials. Chapter 5 presents an overview of gasification technology and discusses the different types of gasification systems that are commonly used today for the recovery of energy. The limitations of each type of gasifier in relation to performance and feedstock conversion are also discussed, including research priority areas that will allow for system optimization in terms of efficiency.

Chapter 6 proposes a novel, clean thermochemical process that harnesses thermal plasma technology to co-produce hydrogen and ammonia using a chemical looping process. The thermodynamic potential and feasibility of the process are demonstrated using a simulation of the system with aluminium and aluminium oxide as the oxygen and nitrogen carriers between the reactors. The effect of different operating parameters, such as feed ratio and temperature of the reactor, on the energetic performance

of the process is investigated. It is demonstrated that the process can operate at an approximate self-sustaining factor of 0.11 and an exergy partitioning fraction of up to 0.65. Integrating the process with solar photovoltaics shows a solar share of 32% without considering any battery storage units.

Finally, Chapter 7 provides an overview of energy efficiency in the mining industry with a particular focus on the role of fuel consumption in hauling operations in mining. Moreover, as the costliest aspect of surface mining with a significant environmental impact, diesel consumption is investigated in this chapter. This research seeks to develop an advanced data analytics model to estimate the energy efficiency of haul trucks used in surface mines, with the goal of lowering operating costs. The visualized results also clarify the general minimum areas in the plotted fuel consumption graphs. These areas potentially open a new window for researchers to develop optimization models to minimize haul truck fuel consumption in surface mines.

> **Petrica Vizureanu** "Gheorghe Asachi" Technical University, Iasi, Romania

Section 1

Heat Recovery

**1**

Section 1 Heat Recovery
