Search

By applying fundamental data and developing simplified correlations while assuming uniform conditions in the cells, the aluminium industry has been able to design better cells and steadily improve the environmental performance, energy, and faradaic efficiencies. However, with the high capital and operating costs of the technology’s retrofits aimed at increasing the productivity of installed capacity, the retrofitted cells have not always been able to sustain their previous environmental standards and production efficiencies. Hence challenges have emerged, with it becoming evident that the changed “physics” such as those contributing to magneto-hydrodynamic stability, alumina dissolution, electrolyte mixing, spatial heat generation and its transfer can all contribute to the deterioration in some of the key performance indicators and operating cost factors. Advancing the technology further is likely to be reliant on developing the design operating and control practices that solve these challenges.

Bioconversion of manure effluents can be considered as a promising and environmentally friendly option for the treatment of manure effluents. These conversion processes may be sustainable and beneficial for the farming and agricultural industry. Physical treatments, including daily spreading, liquid effluent storage, solids separation, odour control and lagoon treatment, can be undertaken before biological or chemical treatments. They do not involve major transformation when it comes to the nature of the manure effluents and its content. They are generally used for conditioning the liquid or solids from the effluent. Chemical treatments of manure effluents are undertaken to improve the removal efficiency of solids, pathogens and odours. They are effective and used with the addition of coagulating agents and pH regulator to significantly improve the quality of the final product being treated from manure effluents. In this review, the main focus is on bioconversion processes. They involve biological reactions and microorganisms activity under defined operating conditions. Aerobic and anaerobic digestion are described as the major biological processes to be explored for manure effluents treatment. They constitute the basis of most processes. Bioconversion involves processes such as composting, biodrying, gasification, cofiring, pelletization, methanol and syngas production, and many others. The majority of these processes lead to the generation of by-products, such as fertilizers and biogas, which can be used in the farming and agricultural activities. Heat generation, clean fuels or renewable energy resources are also generated from manure effluents and they may be useful in the energy sector. Furthermore, many other emerging applications using manure effluents, such as microalgae production, aquaculture, bedding, soil reclamation, are still being developed; they will also contribute to the expansion of the field of bioconversion of manure effluent soon.

Hyperthermia utilizing magnetic particles has been widely studied as a possible method for cancer treatment in recent years. This method induces apoptosis (cell death) using heat generation from magnetic particles which are injected into a tumor region and subjected to an external high-frequency magnetic field. In previous studies, we succeeded in developing microsize thermosensitive ferromagnetic particles with a low Curie temperature of around 40–45 °C as a self-controlled heating element that possibly prevents the local overheating surrounding healthy tissues. Further, by utilizing the change of its permeability around its Curie temperature resulting in the change in the magnetic flux density around tumor region, we also developed a wireless temperature measurement. In addition, to localize magnetic particles which cannot be seen from the body surface, we also developed an automatic localization system by using a robot arm equipped with three detection coils symmetrically installed in heating coil. To make our proposed elemental technologies feasible in clinical settings, we have also been developing a magnetic hyperthermia system that can treat deep-seated tumors up to 5 cm. In this paper, we report our elemental technologies which have been developed so far such as heating elements, temperature and position monitoring technologies.

In the current context related to the environmental impact of buildings, in the field of heat generation and consumptions, there is a multitude of approaches following the main axe—processual sustainability. Within the chapter, the representative typologies of buildings as energy consumers, along with their related heating systems are analyzed, and the possibilities of energetic optimization, in order to reduce the environmental impact, are highlighted and assessed. The chapter includes general notions in the field, current and prefigurative stages of the future sustainable energetic concept and the importance of stepping up the optimization process to reach them, in the case of existing heating systems. The concepts of conventional and renewable thermoenergetic hub are presented. The modern concept of energy hub, which allows the correspondence of a single energy output, the buildings’ heat demand, with several energy inputs, associated with various energy carriers—conventionals, renewables or alternatives, is analyzed from the energetic and environmental point of view. The performance indicators are defined within the frame of the renewable energy based thermoenergetic hub. The representative indicators regarding the environmental impact, the energy and carbon footprints are highlighted. Based on targeted indicators, the possibilities of decarbonisation of the thermoenergetic systems in the buildings’ sector, particularly the increase of the energy efficiency of the buildings and the related heating systems are analysed regardfully for the environment. A case study on the carbon environmental impact of heating systems is presented, followed by discussion and conclusion.

The skeletal system has multiple functions including protection of vital organs, contributing to posture, serving as a reservoir for calcium and phosphorus, housing cells which develop into blood cells, and serving as locations on which muscles act to produce the movements permitted by the joints. Joints, which are locations where two or more bones are united, are also an important component of the skeletal system. Two important tissues compose this system. Cartilage is a specialized type of connective tissue that consists of chondrocytes surrounded by an extracellular matrix of fibers and ground substance, whereas bone is a specialized type of connective tissue that consists of osteocytes surrounded by an extracellular matrix also composed of fibers and ground substance. Bone formation occurs in two different ways: intramembranous formation and endochondral formation. Partnering with the skeletal system, the muscular system produces movement, contributes to heat generation, and assists with posture. It is composed of skeletal muscle tissue, which in turn is composed of long, thin cells known as fibers.

In friction stir welding (FSW) the material is welded without melting the base material. Aerospace, automobile, shipbuilding and electronics are some of the industrial sectors which use FSW for manufacturing of components. It is primarily used because of higher weld efficiency as compared with fusion joining processes. In this book chapter, the fundamental aspects of the FSW have been briefly discussed. The chapter also discusses the effect of input responses on the output responses, application of FSW in various industries, research advances in welding of similar and dissimilar material using FSW. The FSW tool has two major features namely, the shoulder and pin, as its shape and dimensions govern the material flow behavior. In general, a cylindrical tool is used for FSW. Tool rotational speed, tilt angle, welding speed, and plunge depth are the input conditions which affect the dynamics of the process. Changes in these parameters have an effect on axial force, spindle torque, temperature distribution/heat generation and strain. In addition, it ultimately changes the microstructural, hardness and weld strength. The choice of the workpiece and tool material for FSW is another big challenge as it has its own limitations. Application of FSW started with welding of aluminum and magnesium and its alloy but eventually, it gained traction in welding high-density metals like copper, titanium and steel. Welding of these materials requires a hard tool material with the better thermomechanical property as compared to the workpiece to avoid premature tool wear/failure. FSW is not only limited to similar metal welding but research is going for welding of material in the dissimilar configuration like aluminum with copper, magnesium with aluminum, and steel with aluminum etc. The successful evolution of FSW has led to the emergence of a few new variants of this technology such as friction stir additive manufacturing, friction stir processing, friction stir spot welding, and micro FSW.

Abrasive water jet machining (AWJM) is an interesting solution for the production of shallow pockets in metal sheets made of titanium alloys. Indeed, it produces low cutting forces and heat generation and prevents deformation of these parts after machining. In addition, it has the advantage of only using two raw materials: sand and water. It is possible to generate pocket edges with an imposed geometry using AWJM, but it is necessary to tilt the axis of the jet. The material removal mechanism is then a function of the inclination angle. The presented study propose an improved model for modelling the pocket profile in TiAl6V parts. The experimental results shows that the model is efficient as the precision is around 5%.

We consider the problem of energy-optimally mapping a set of moldable-parallel tasks in the steady-state pattern of a software-pipelined streaming computation onto a generic many-core CPU architecture with a 2D mesh geometry, where the execution voltage and frequency levels of the cores can be selected dynamically from a given set of discrete DVFS levels. We extend the Crown Scheduling technique for parallelizable tasks to temperature-aware scheduling, taking into account the tasks’ heat generation, the heat limit for each core, and the heat diffusion along the 2D mesh geometry of typical many-core CPU architectures. Our approach introduces a systematic method for alternating task executions between disjoint “buddy” core groups in subsequent iterations of crown schedules to avoid long-time overheating of cores. We present two integer linear program (ILP) solutions with different degrees of flexibility, and show that these can be solved for realistic problem sizes with today’s ILP solver technology. Experiments with several streaming task graphs derived from real-world applications show that the flexibility for the scheduler can be greatly increased by considering buddy-cores, thus finding feasible solutions in scenarios that could not be solved otherwise. We also present a fast heuristic for the same problem.

The paper investigates the heat formation and absorption processes in the cement-water system. The temperature gradient in a cement composition is one of the mainsprings of cement hydration and curing and the formation of final properties of the cement-water system. The differential calorimetric analysis based on measuring the temperature difference between dry and wet cement shows the reciprocal, cyclic heat formation. The observed effects are caused by the processes of dispersion and hydration of cement particles and crystallization of cement hydration products. Three types of harmonic frequencies are detected for the heat formation, viz. 1–3 vibrations per minute, ~12 h, and a several days vibration period. The heat formation-based analysis of phenomena observed in the cement-water system shows self-excited vibrations during the cement hydration and curing. The reaction continues owing to the energy release during hydration of clinker minerals and dispersion of the initial cement particles. The high sensitivity of the differential calorimetry as against the integral methods provides the deeper understanding of the phenomena observed and allows improving the cement potential in the production of a wide range of building materials.

Worldwide, higher temperatures occur in urban areas (UHI - Urban Heat Island) compared to the surrounding countryside, with a considerable impact on people's health and well-being. Extensive use of paved surface and bituminous materials and human activity heat generation are the major causes of the UHI. The paper points out the importance of bituminous pavements on UHI and reports the empirical evaluation performed in Cagliari (Italy). Using thermal data from the Italian SmartRunway located in Cagliari airport, a fitting empirical model developed for bituminous pavement surface (R2 81%).

Earth scientists have modeled the global impacts of human fossil fuel energy use and heat generation for 50 years as ecologists have tried to propose remedial programs to counter the predicted, impending catastrophe. This paper traces the history of modeling urban form during the same period, interlacing the hybrid discipline of Urban Design between the models of City Planning and Architecture. The paper presumes a familiarity with basic urban design elements such as the enclave, armature and heterotopia. The paper matches these elements against predominant energy supply patterns to trace the contemporary emergence of urban fragmentation and patch dynamics in complex systems. The three models of Kevin Lynch, the City of Faith, the City Machine and the Ecocity form the basis of the analysis framed within a fourth contemporary model, the informational Metacity/Megacity. This model has the capacity to track, trace and manage the previous urban forms and their relationships at multiple scales. The paper shows that heterotopias, ambiguous patches and spaces of change have played an important part in previous energy transitions. The question is whether, given the current global energy bias to oil and gas, new urban life forms can emerge in time to meet the needs of future generations? There remain strange spaces of hope where humans have produced urban environments of beauty under great stress. Such past experiments could possibly provide answers for future conditions.

We consider the results of the experimental studies of the impact of the intake charge heating with exhaust gases on the nature of in-cylinder processes in a diesel engine at low ambient temperatures. We also compare them with the results of starting a diesel engine without heating. In this case, we select various environmental conditions (ambient temperature) and the intake air heating degree. We present underlying mathematical dependencies used to process the results of the experimental studies and to calculate the parameters of the generation and use of heat in the diesel engine cylinder. To determine the amount of released heat, we use the concept of the entropy of the working fluid and assume that the chemical composition of the working fluid remains unchanged. During the experimental studies, we obtained indicator diagrams for various diesel engine starting conditions. After processing them, we receive graphical dependencies of the changes in the average gas temperature and heat generation in the engine cylinder. We determine that it is expedient to use the intake air heating within the range of 50…60 K at low ambient temperatures of up to 250 K. In this case, the proportion of excess clean air in the intake charge is rα = 0.80–0.83, and the combustion efficiency coefficient is ξ = 0.45–0.50.

Mechanical surface hardening processes have long been of interest to science and technology. Today, surface modification technologies have reached a new level. One of them is friction stir processing that refines the grain structure of the material to a submicrocrystalline state. Previously, the severe plastic deformation occurring during processing was mainly described from the standpoint of temperature and deformation, because the process is primarily thermomechanical. Modeling of friction stir welding and processing predicted well the heat generation in a quasi-liquid medium. However, the friction stir process takes place in the solid phase, and therefore the mass transfer issues remained unresolved. The present work develops the concept of adhesive-cohesive mass transfer during which the rotating tool entrains the material due to adhesion, builds up a transfer layer due to cohesion, and then leaves it behind. Thus, the transfer layer thickness is a clear criterion for the mass transfer effectiveness. Here we investigate the effect of the load on the transfer layer and analyze it from the viewpoint of the friction coefficient and heat generation. It is shown that the transfer layer thickness increases with increasing load, reaches a maximum, and then decreases. In so doing, the average moment on the tool and the temperature constantly grow, while the friction coefficient decreases. This means that the mass transfer cannot be fully described in terms of temperature and strain. The given load dependence of the transfer layer thickness is explained by an increase in the cohesion forces with increasing load, and then by a decrease in cohesion due to material overheating. The maximum transfer layer thickness is equal to the feed to rotation rate ratio and is observed at the axial load that causes a stress close to the yield point of the material. Additional plasticization of the material resulting from the acoustoplastic effect induced by ultrasonic treatment slightly reduces the transfer layer thickness, but has almost no effect on the moment, friction coefficient, and temperature. The surface roughness of the processed material is found to have a similar load dependence.

District heating networks present a high potential for the transition of the heat energy sector, both technically and organisationally. They allow integration of renewable energy, improve the overall energy efficiency, as well as facilitate sector coupling (coupling between heating, electricity and mobility). Many district heating systems could be upgraded by improvements at the side of the heat consumption, heat distribution and heat generation. The EU project Upgrade DH (H2020; Contract No. 785014; www.upgrade-DH.eu) supports the upgrading and retrofitting process of DH systems in different climate regions of Europe, covering various countries. Core activities of the Upgrade DH project include the collection of the best upgrading measures and tools, the support of the upgrading process for selected district heating networks, the organisation of capacity building measures about DH upgrading, financing and business models, as well as the development of national and regional action plans. Overall Upgrade DH approach should lead to more efficient district heating networks and sustainable solution for the heating sector. The specific upgrading opportunities need to be identified, described, assessed and translated into Key Performance Indicators (KPI) which may allow the results to be monitored as the action gets implemented. In this paper, the upgrading method is demonstrated on Tuzla DH, one of demo-cases considered under Upgrade DH project. In developing the upgrading measures for Tuzla DH, three measurable objectives 20/20/20 were taken into account, namely (i) 20% increasing energy efficiency (reducing annual primary energy demand from 350 GWh down to 270 GWh), (ii) 20% increasing RES (from 0 up to 20% of RES) and (iii) 20% reducing CO2 emission (CO2 cut from today 115,000 t/a emitted in producing 350 GWh of heat down to max. 92,000 tCO2/a. By identified and prepared upgrading measures, those targets are highly exceeded.

Aluminum alloys are widely used in manufacturing industry due to its beneficial combination of formability and strength. However, these alloys are prone to imperfections when joined using conventional fusion welding technologies. A revolutionary solid-state welding technique, labeled Friction Stir Welding (FSW), was demonstrated to be particularly suited for aluminum alloys joining. This solid-state welding process produces joining by mixing materials under intense plastic deformation and heat generation. To gain insight into the base material flow and heat generation during FSW, 3D coupled thermo-mechanical finite element model (FEM) was developed to reproduce the friction stir spot welding (FSSW) variant of FSW process. The numerical model, which uses an Arbitrary Lagrangian Eulerian (ALE) formulation, was implemented in ABAQUS/Explicit. The constitutive behavior of the base material was modeled using the classical Johnson-Cook model. The developed FE model was used to predict and compare the temperature distributions, forces and torques during FSSW of AA6082-T6 and AA5083-H116 aluminum alloys. Some conclusions on AA6082-T6 and AA5083-H116 aluminum alloys weldability in FSSW will be presented based on the comparative analysis of numerical and experimental results.

Cutting of solid construction materials during repair and restoration work is carried out with diamond discs and CBN discs on a metal bond with speeds up to 80 m/s. The cutting process is accompanied by significant heat generation, as a result of which the cutting disc heats up intensively. When heated to a temperature of 500–600 °C, the strength characteristics of the disk are halved, which can lead to rupture and seizure of the disk and loss of the diamond layer. Disk heating temperature should not exceed 600 °C. The operating time of the diamond cutting disc is the time during which it is heated during continuous operation to a temperature of 600 °C. The cooling media used in cutting are intensively discarded by the air flows of the boundary layer of air that circulate near the rotating circle. Knowing the speed and dimensional characteristics of these flows, we can develop a rational cooling system. The purpose of the study is to determine the conditions of transportation of cooling media, ensuring their guaranteed entry into the cutting zone to create the maximum cooling effect. This work defines the speeds of flowing air in the near-wall area and in the area tangential to the disk with the help of mathematical modeling. The thickness of the air layer, which rotates at a speed of up to 0.5 circle speed was determined, taking this value as the “boundary layer thickness”. The change in air pressure in the cutting zone between the cutting grains was determined, too. It is established that air pressure can vary from 0.5–1.7 MPa. In this regard, the cooling medium supplied under the circle, inevitably displaced from the cutting zone. In order for the cooling medium to penetrate into the cutting zone, it must be fed under a pressure that exceeds the air pressure in the cutting zone.

The carbon anodes in a Hall-Heroult cell are continuously consumed and thus require periodic replacement. During the setting of a cold new anode, bath freezes around it, causing the anode current flow to be impeded and redistributed to the other anodes. The anode setting event introduces significant disturbances which affects cell stability and thermal balance. Common work practices, such as anode beam raising, affect the bath temperature in the entire cell, even for regions far away from where the anodes will be set. With measurements of anode current distribution, control strategies for anode setting can be optimized and improved, for example by preheating the region where anodes will be set. In this paper, the effects of raising groups of anodes on the distribution of bath temperature is investigated. The results show that heat generation can be targeted to specific regions in the bath, as well as to minimize the unwanted effect on ledge profile. Additionally, contrary to simple intuition, raising anodes in a particular bath region is shown to have a greater effect on other bath regions.

The scheme of the formation of the accuracy of parts in the grinding technological system under the action of the varying temperature of used working fluids is given. The main sources of heat in the hydraulic system of grinding machines are specified. The basic reasons for heat generation in the coolant application subsystem are outlined. Mathematical dependencies for determining of thermal parameters of coolant and elements that are in contact with it are given. The issues related to the generation of working fluid temperature in the front and end spindle bearings are considered. The experimental data of the effect of ambient temperature on the temperature in the main tank, the temperature of the working fluids in the spindle bearings at the initial time and after 6 h of machine operation are given. The results of the study of the coolant temperature at the exit from the coolant tank and cutting zone with computer simulation are presented.

Magnetic nanoparticles have been extensively in the biomedical field as drug delivery agent, diagnosis of different diseases and more recently in the treatment of different types of cancer. Majority of these studies reported the use of iron oxide nanoparticles or formulation contains at least iron in most of magnetic-based nanosystems. Focus on iron oxide nanoparticles is mainly due to their superparamagnetic nature at nanoscale and other features such as higher surface to volume ratio, biocompatibility and low toxicity. For further improvement in their properties, doping with different transition metal elements is also under investigations. This chapter covers most commonly used types of iron oxide NPs, behavior with few doping metals in iron oxide nanoparticles and their synthesis protocols through different physical and chemical methods. Finally, heat generation mechanisms responsible for localized heat in tissues have been discussed.

The divergence of thermally radiative MHD flow of a Casson nanofluid over a stretching paper alongside heat absorption. The governing non linear equations are remodeled into a nonlinear ODE’s. The HAM is adopted to find the series solution. The changes of pertinent parameters are analyzed with diagrams and tables. The fluid velocity is controlled by suction and it develops with injection. The local Nusselt number rapidly suppresses with increasing the magnetic field parameter in heat generation case.

A global estimate for the generation of solid waste is projected to be ~1.3 billion tonnes/year. This volume is supposed to further increase up to 2.2 billion tonnes/year by the mid of 2030. In this context, the effective treatment and disposal of solid waste around the globe is becoming of utmost importance. Moreover, sustainable management of solid waste is not only necessary to solve the disposal issues but also beneficial in terms of energy production. Developed countries have already adopted technologies for utilization of their solid waste in energy production, heat generation, conversion to biofuel, compost preparation and as the metal reservoir. In contrast, developing countries are still struggling to manage their solid waste as an alternative resource. Amongst all other ways of solid waste management, the waste-to-energy (WtoE) technology is better suitable for developing countries in terms of building up their energy resources. In this chapter, the status of solid waste in the developing nations along with their WtoE options is being discussed. Moreover, the cost estimation has marked as significant tool to identify suitable WtoE option for developing countries.