High-temperature Industrial Processes Research Articles

A tracer-free photographic method for the estimation of the velocity field in a liquid metal pool

Abstract Accurately measuring the velocity field (VF) of liquid metals is essential for optimizing and controlling high-temperature industrial processes, yet remains a challenging task despite the numerous existing velocimetry techniques. In this paper, a methodology for estimating the VF of a liquid metal pool is proposed. The experimental set-up used here to heat the metal sample up to the liquid state and collect data is presented. This set-up primarly intented to perform flash experimetns on liquid metals, allows contactless heating and data measurements by a high speed camera. The proposed methodology for estimating the VF consists then in implementing a Non-Rigid Registration between the different frames of the recorded temperature fields (TFs). This method is applied on TFs resulting from multiple experimental tests conducted on iron samples in the temperature range of 1 850 − 2 100 K. The consistency of the results is put to test via multiple validation tests. The influence of the main parameters is also evaluated. The results show that the proposed methodology allows a fine experimental quantification of liquid metal VFs with an estimated error of 8 % and confirm the feasibility of the proposed approach.

Numerical Investigation of Shell-Side Flow Behavior and Vapor Distribution in Waste Heat Boilers.

Shell-and-tube waste heat boilers (STWHBs) are essential in the recovery of waste heat from high-temperature industrial processes. Kettle-type STWHBs are known to experience failures due to hold-up of steam, a significant concern in the industry. Multiphase computational fluid dynamics (CFD) simulations are used to study the effect of tube layout on the steam hold-up of an industrial-scale STWHB. Different design specifications are simulated including tube layout, heat flux, and pitch to predict steam hold-up performance and analyze thermo-hydrodynamic phenomena within the tube bundle. Simulation results show that, for similar tube bundle shape and size, 45° rotated square tube bundle layouts perform better, with respect to steam hold-up, than the square and triangle layouts for a range of heat flux duties. It is found that steam hold-up increases linearly with increasing heat flux and decreasing tube pitch, for the conditions simulated. The turbulent kinetic energy of the bubbly flow is greatly influenced by increasing phase fraction. Visualizations of the flow of water and steam within and around the tube bundle show that there is a vertical flow deviation for both staggered tube patterns (rotated square and triangle). These results motivate further multiphase CFD-based study of the thermo-hydrodynamics of STWHBs for improved understanding, retrofit, and new designs.

Получение покрытий с высокой инфракрасной излучательной способностью

Introduction. One of the promising modern methods of coating formation is detonation gas dynamic sputtering. Coatings obtained by this method have high adhesion to the substrate, dense structure and specified functional properties. Development of technology for obtaining functional coatings with high emission coefficient in the infrared range is an urgent need for the development of high-temperature industrial processes and technologies. High-temperature industrial processes consume a large amount of energy, so improving the energy efficiency of industrial equipment is considered as one of the ways to overcome the ever-growing energy crisis. To this end, coatings with high infrared emissivity have been developed for industrial furnaces. These coatings are usually applied to the furnace walls, which significantly improves energy efficiency by increasing heat transfer from the heat-emitting surfaces of the furnace. The purpose of the work is to obtain coatings with high emission indices in the infrared range for further recommendation of its use in baking ovens of Shebekinsky machine-building plant. Methods for studying coating specimens obtained by detonation gas-thermal method: scanning electron microscopy, X-ray phase analysis, energy dispersive analysis, infrared spectroscopy. Results and discussion. The microstructure, phase composition, emissivity and thermal cycling resistance of Fe2O3; Al2O3 + 10 % Fe2O3; Ti + 10% Fe2O3 coatings obtained by detonation gas-dynamic powder spraying are investigated in this work. The results of the study showed that the obtained coatings have a dense structure, increased emissivity and resistance to thermal treatment cycles, as a result of which the structure of the crystal lattice of the coatings does not change.

DFT and AIMD insights into heterogeneous dissociation of 2-chlorothiophenol on CuO(111) surface: Impact of H2O and OH

Copper oxides are vital catalysts in facilitating the formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) through heterogeneous reactions in high-temperature industrial processes. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. The initial step in this process is the metal-catalyzed production of chlorothiophenoxy radicals (CTPRs) from CTPs via dissociation reactions. This work combines density functional theory (DFT) calculations with ab initio molecular dynamics (AIMD) simulations to explore the formation mechanism of the adsorbed 2-CTPR from 2-CTP, with the assistance of CuO(111). Our study demonstrates that flat adsorption configurations of 2-CTP on the CuO(111) surface are more stable than vertical configurations. The CuO(111) surface acts as a strong catalyst, facilitating the dissociation of 2-CTP into the adsorbed 2-CTPR. Surface oxygen vacancies enhance the adsorption of 2-CTP on the CuO(111) surface, while moderately suppressing the dissociation of 2-CTP. More importantly, water molecules and surface hydroxyl groups actively promote the dissociation of 2-CTP. Specifically, water directly participates in the reaction through “water bridge”, enabling a barrier-free process. This research provides molecular-level insights into the heterogeneous generation of dioxins with the catalysis of metal oxides in fly ash from static and dynamic aspects, providing novel approaches for reducing dioxin emissions and establishing dioxin control strategies.

Formation of Pre-PCTA/DT Intermediates from 2-Chlorothiophenol on Silica Clusters: A Quantum Mechanical Study.

Silica (SiO2), accounting for the main component of fly ash, plays a vital role in the heterogeneous formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) in high-temperature industrial processes. Silica clusters, as the basic units of silica, provide reasonable models to understand the general trends of complex surface reactions. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. By employing density functional theory, this study examined the formation of 2-chlorothiophenolate from 2-CTP adsorbed on the dehydrated silica cluster ((SiO2)3) and the hydroxylated silica cluster ((SiO2)3O2H4). Additionally, this study investigated the formation of pre-PCTA/DTs, the crucial intermediates involved in PCTA/DT formation, from the coupling of two adsorbed 2-chlorothiophenolates via the Langmuir-Hinshelwood (L-H) mechanism and the coupling of adsorbed 2-chlorothiophenolate with gas-phase 2-CTP via the Eley-Rideal (E-R) mechanism on silica clusters. Moreover, the rate constants for the main elementary steps were calculated over the temperature range of 600-1200 K. Our study demonstrates that the 2-CTP is more likely to adsorb on the termination of the dehydrated silica cluster, which exhibits more effective catalysis in the formation of 2-chlorothiophenolate compared with the hydroxylated silica cluster. Moreover, the E-R mechanism mainly contributes to the formation of pre-PCTAs, whereas the L-H mechanism is prone to the formation of pre-PCDTs on dehydrated and hydroxylated silica clusters. Silica can act as a relatively mild catalyst in facilitating the heterogeneous formation of pre-PCTA/DTs from 2-CTP. This research provides new insights into the surface-mediated generation of PCTA/DTs, further providing theoretical foundations to reduce dioxin emission and establish dioxin control strategies.

Computational study of double diffusive MHD natural convection flow of non-Newtonian fluid between concentric cylinders

This study investigated double diffusion natural convection of Casson fluids in an asymmetrical cavity under a constant magnetic field. The intricacies of flow and heat/mass transfer were explored computationally using the finite element method. With applications in fields such as geology, oceanography, metallurgy, and astrophysics, it investigates the impact of key parameters like the Rayleigh number, Casson parameter, buoyancy ratio, Hartmann number, and Darcy number on entropy generation, fluid velocity, and temperature/concentration gradients. The findings illustrate that increasing the Rayleigh number enhances convection and entropy, while a higher Casson parameter leads to reduced mixing due to the fluid's more solid-like behavior. Enhancing the buoyancy ratio improves heat and mass transfer, and a greater Darcy number boosts convection efficiency. Additionally, a higher Hartmann number reduces fluid friction but increases mass diffusion and magnetic disorder, subtly improving thermodynamic efficiency. This research offers valuable insights for optimizing heat transfer and energy efficiency in high-temperature industrial processes, contributing to advancements in sustainability and energy utilization.

Transient-liquid-phase bonding for Skutterudite-based thermoelectric modules

Thermoelectric (TE) generators are an option for waste heat recovery in a large diversity of applications, such as automotive, aerospace or high temperature industrial processes with high energy throughput. Skutterudite materials are among the most interesting candidates for high efficiency modules in the high-temperature range up to 500 °C. However, Skutterudite-based TE modules still lack published results on reliable solutions for electrical and thermal contacts between the semiconducting TE pellets and metallic bridges and their stability under thermal treatment, leaving room for suggestions on durable joining and assembly technology.In this article we will present contacting schemes for TE couples using different diffusion barriers and a transient liquid phase (TLP) joining process. The joints have been investigated concerning their microstructure, diffusion effects and electrical contact resistivities. CrSi2 has shown suitable as anti-diffusion layer with good adhesion and electrical properties leading to contact resistivities as low as 5 μΩ cm2.

Temperature influence on minimum fluidization velocity: Complexity, mechanism, and solutions

Fluidized-bed reactors are widely employed in various high-temperature industrial processes. Thus, it is crucial to understand the temperature effect on various fluidization phenomena, specifically the minimum fluidization velocity (Umf) that governs various aspects of fluidized bed behavior. In this study, we comprehensively analyze Umf data from the literature to unravel the complexity and underlying mechanisms of temperature influence on this critical velocity. The research examines experimental data encompassing a wide range of temperatures, pressures, and solid particles. The analysis reveals that the influence of temperature on Umf is fundamentally determined by the relative importance of hydrodynamic forces and interparticle forces within fluidized beds and is realized by three distinctive temperature-induced changes: gas properties, bed voidage, and physiochemical characteristics of particles. On this basis, an equation is derived to enable predictions of temperature influences on the minimum fluidization velocity under broad temperature conditions.

Thermal Effects on Prefabricated Box Culverts and Implications for Joint Performance under Elevated Temperatures

With the rapid progression of urbanisation and the continual refinement of transportation networks, prefabricated box culverts have increasingly attracted attention as modern structural components. Their rapid construction and environmentally friendly characteristics have rendered them a favoured choice within the engineering community. However, under high-temperature conditions, such as in fires or high-temperature industrial processes, concerns remain about the temperature distribution within these culverts and the subsequent impact on joint performance. Although some studies have addressed the temperature distribution and thermal effects associated with these culverts, most have been grounded in theoretical assumptions or have only engaged in preliminary experiments. In this research, an in-depth analysis of the temperature distribution within prefabricated box culverts under high-temperature conditions and the implications for joint performance is undertaken. Advanced finite element analysis tools are utilised for simulations. The findings provide the engineering community with comprehensive and precise reference data, holding significant implications for the design, construction, and maintenance of future prefabricated box culverts.

Techno-economic assessment from a transient simulation of a concentrated solar thermal plant to deliver high-temperature industrial process heat

The need for new technologies to provide economically viable sources of high-temperature heat without any net CO2 emissions for industrial chemical processes has become a global priority. Concentrated solar thermal heat generation can play an important role in meeting this challenge. We report a detailed bottom-up techno-economic analysis of a concentrated solar thermal plant to deliver process heat at a temperature of 1100 °C at the scale anticipated for a commercial demonstrator. The system consists of a 50 MWth solar concentration subsystem with heliostats and a tower, a novel solar expanding-vortex particle receiver (SEVR) and a packed bed storage system, together with a combustion back-up to allow continuous operation. The system was optimized to determine the minimum levelized cost of heat (LCOH) from a detailed transient model of the complete system. Significantly, the system with the maximum efficiency for the receiver or storage alone does not deliver the best annual energetic performance, highlighting the need to understand the detailed interplay between the two systems to optimize overall performance. While this system is not yet optimized for the lowest cost of industrial heat, the sensitivity analysis provides important insight as to how to move toward this optimum. This system yields the lowest values of LCOH for the solar component of between 37 and 39 USD/GJ for a corresponding annual solar share (SSann) of 28% and 53% of the total heat demand of the industrial process, respectively. However, importantly, this solar share can be almost doubled for only a 5% increase in LCOH.

A molten salt test loop for component and instrumentation testing

Molten salt is an effective coolant for a wide range of applications, including nuclear reactors, concentrated solar power, and other high temperature industrial heat transfer processes. The technical readiness level of components and instrumentation for high-temperature molten salt applications needs improvement for molten salt to be more widely adopted. A molten salt test loop was designed, built, and commissioned as a test bed to address these issues. The molten salt test loop at Abilene Christian University was built out of 316 stainless steel with a forced flow centrifugal-type pump, and was instrumented for remote operation. A low-temperature molten nitrate salt was used in this system, which was designed to operate at temperatures up to 300°C and flow rates up to 90 liters per minute.This paper describes the loop design, computational fluid dynamics modeling, construction, and commissioning details. An outline of the data acquisition and control systems is presented. Salt samples were taken before and after introduction into the loop, and melting points were measured both before and after salt circulation. Performance of the system is discussed as well as improvements required for higher temperature loops envisioned for the future.

Pathways to the use of concentrated solar heat for high temperature industrial processes

Pathways to the use of concentrated solar heat for high temperature industrial processes

Nature‐Inspired High Temperature Scale‐Resistant Slippery Lubricant‐Induced Porous Surfaces (HTS‐SLIPS) (Small 46/2022)

Scale Formation Scale formation is a longstanding and unresolved problem in a number of areas. In article number 2203615, Steven Wang and co-workers present a nature-inspired high-temperature scale-resistant slippery lubricant-induced surface (HTS-SLIPS) showing excellent scale resistance under extreme conditions. It is anticipated that the simple and scalable coating fabrication approach will be applicable in numerous industrial high-temperature processes where scale formation is encountered.

Nature-Inspired High Temperature Scale-Resistant Slippery Lubricant-Induced Porous Surfaces (HTS-SLIPS).

Scale formation is a longstanding and unresolved problem in a number of fields, including power production, petroleum exploration, thermal desalination, and construction. Herein, a high-temperature scale-resistant slippery lubricant-induced surface (HTS-SLIPS) is developed by one-step electrodeposition and lubricant infusion. The fractal cauliflower-like morphology with lubricant oil is conducive to forming an ultralow contact angle hysteresis of ≈1°. The 10-d real-world boiling trial indicates that by replacing the uncoated surface with HTS-SLIPS, the reduction in scale mass is greater than 200% because of the low surface free energy (4.3 mJ m-2 ) and outstanding smoothness (Ra = 41 ± 8nm) of HTS-SLIPS. Thanks to the scale retardation, the bubble departure frequency of HTS-SLIPS is eightfold higher than that of uncoated surfaces, signifying superior heat transfer efficiency. In these demonstrations, HTS-SLIPS coated spiral tube exhibits better flowability and lower pressure drop than the uncoated one. In addition, favorable compatibility between HTS-SLIPS and mechanical vibration is experimentally verified to strengthen the descaling of SLIPS synergistically. It is anticipated that the simple and scalable coating fabrication approach will be applicable in numerous industrial high-temperature processes where scale formation is encountered.

Coupling Chemical Heat Pump with Nuclear Reactor for Temperature Amplification by Delivering Process Heat and Electricity: A Techno-Economic Analysis

The energy economy is continually evolving in response to socio-political factors in the nature of primary energy sources, their conversions to useful forms, such as electricity and heat, and their utilization in different sectors. Nuclear energy has a crucial role to play in the evolution of energy economy due to its clean and non-carbon-emitting characteristics. A techno-economic analysis was undertaken to establish the viability of selling heat along with electricity for an advanced 100 MWth small modular reactor (SMR) and four nuclear hybrid energy system (NHES) configurations featuring the SMR paired with chemical heat pump (ChHP) systems providing a thermal output ranging from 1 to 50 MWth. Net present value, payback period, discounted cash flow rate of return, and levelized cost of energy were evaluated for these systems for different regions of U.S. reflecting a range of electricity and thermal energy costs. The analysis indicated that selling heat to high temperature industrial processes showed profitable outcomes compared to the sale of only electricity. Higher carbon taxes improved the economic parameters of the NHES alternatives significantly. Providing heat to high temperature industries could be very beneficial, helping to cut down the greenhouse gases emission by reducing the fossil fuel consumption.

Analysis on the sustainability of different low CO2 emission Hydrogen production technologies for transition towards a ‘zero emission’ economy

Abstract World primary energy consumption reached 14,2 mil. tons of oil equivalent. More than 81.7% of this energy was generated from fossil fuels as primary energy source while 74.5% of the electrical energy was generated from fossil fuels. Energy transition towards zero impact from CO2 emission requires a major shift in the energy mix of the primary sources, decarbonization of the electricity generation, and the use of Hydrogen as the alternative low CO2 emission solution for the high temperature industrial process. Low CO2 Hydrogen could be produced using the conventional technologies (steam methane reform i.e.) with Carbon Capture and Storage, from renewable energy sources through water electrolysis or from biogas / biomass. At this moment none of the low CO2 Hydrogen technologies is competitive, as natural gas-based Hydrogen is around 1.5 EUR/kg while renewable based Hydrogen is in the range of 2.5-5.5 EUR/kg. From the sustainability point of view, besides the production cost issue, the whole life cycle emissions need to be considered. The main goal of this article is to assess different low CO2 emission Hydrogen production technologies by analyzing the CO2 emission along the value chain, together with a sensitive analysis on the main cost drivers, evaluating the impact on upstream and downstream economic sectors, based on case study methodology. This article provides the basis for selecting the most sustainable technology, the prerequisites for an energy transition towards a hydrogen-based economy and highlights the critical links between a Low CO2 Hydrogen transition strategy and other energy strategies. The results suggest that access to low-cost renewable electricity will be the most important factor in driving the production cost down, a decentralized onsite production will further reduce the losses and wind based renewable energy is having the lowest CO2 emission across the entire life cycle.

Effect of Thermal Exposure on Residual Properties of Wet Layup Carbon Fiber Reinforced Epoxy Composites.

Ambient cured wet layup carbon fiber reinforced epoxy composites used extensively in the rehabilitation of infrastructure and in structural components can be exposed to elevated temperature regimes for extended periods of time of hours to a few days due to thermal excursions. These may be severe enough to cause a significant temperature rise without deep charring as through fires at a small distance and even high-temperature industrial processes. In such cases, it is critical to have information related to the post-event residual mechanical properties and damage states. In this paper, composites are subjected to a range of elevated temperatures up to 260 °C over periods of time up to 72 h. Exposure to elevated temperature regimes is noted to result in a competition between the mechanisms of post-cure that can increase the levels of mechanical characteristics, and the deterioration of the resin and the bond between the fibers and resin that can reduce them. Mechanical tests indicate that tensile and short beam shear properties are not affected negatively until the highest temperatures of exposure considered in this investigation. In contrast, all elevated temperature conditions cause deterioration in resin-dominated characteristics such as shear and flexure, emphasizing the weakness of this mode in layered composites formed from unidirectional fabric architectures due to resin deterioration. Transitions in failure modes are correlated through microscopy to damage progression both at the level of fiber-matrix interface integrity and through the bulk resin, especially at the inter-layer level. The changes in glass transition temperature determined through differential scanning calorimetry can be related to thresholds that indicate changes in the mechanisms of damage.

Bottom-Up Estimates of the Cost of Supplying High-Temperature Industrial Process Heat from Intermittent Renewable Electricity and Thermal Energy Storage in Australia

We report the upper and lower bounds for the levelized cost of high-temperature industrial process heat, supplied from electricity generated with solar-photovoltaic (PV) and wind turbines in combination with either thermal or electric battery storage using hourly typical meteorological year (TMY) data, in systems sized to supply between 80% and 100% of continuous thermal demand at a site in the northern part of Western Australia. The system is chosen to supply high-temperature air as the heat transfer media at temperatures of 1000 °C, which is a typical temperature for an alumina or a lime calcination plant. A simplified model of the electrical energy plant has been developed using performance characteristics of real PV and wind systems and TMY data of renewable energy resources. This was used to simulate a large sample of possible system configurations and find the optimal combination of the renewable resources and storage systems, sized to provide renewable shares (RES) of between 80% and 100% of the yearly demand. This allowed the upper and lower bounds to be determined for the cost of heat based on two scenarios in which the excess energy is either dumped (upper bound) or exported to the electricity grid (lower bound) at the average generating cost. The lower bound of the levelized cost of energy (LCOEL), which occurs for the system employing thermal storage, was estimated to range from USD 10/GJ to USD 24/GJ for RES from 80 to 100%. The corresponding upper bound (LCOEU), also estimated for the system using thermal storage, are between USD 16/GJ and USD 31/GJ, for RES between 80% and 100%. The utilization of electric battery storage instead of thermal storage was found to increase the LCOE values by a factor of two to four depending on the share of renewable energy. Compared with current Australian natural gas cost, none of the systems assessed configurations is economical without either a cost for CO2 emissions or a premium for low-carbon products. The estimated cost for CO2 emission that is needed to reach parity with current natural gas prices in Australia is also presented.

Electrochemical Noise Response of Cr2Nb Powders Applying Mechanical Alloying

Cr2Nb alloys are potential candidates for high-temperature structural materials. The influence of different mechanical alloying parameters (milling time) and sintering processes were studied. After mechanical alloying and observation by scanning electron microscope (SEM), nano powders were characterized and then sintered by spark plasma sintering (SPS). Electrochemical noise (EN) tests were also conducted in order to study the electrochemical behavior. From the current experimental results, it was revealed that ball milling times up to 20 h may explain the influence of Nb–Cr alloys and its association to the Laves phase and corrosion behavior. These insights aimed at improving the samples’ predicted behavior before spending time and resources at high-temperature industrial processes.

Current Legislative Framework for Green Hydrogen Production by Electrolysis Plants in Germany

(1) The German energy system transformation towards an entirely renewable supply is expected to incorporate the extensive use of green hydrogen. This carbon-free fuel allows the decarbonization of end-use sectors such as industrial high-temperature processes or heavy-duty transport that remain challenging to be covered by green electricity only. However, it remains unclear whether the current legislative framework supports green hydrogen production or is an obstacle to its rollout. (2) This work analyzes the relevant laws and ordinances regarding their implications on potential hydrogen production plant operators. (3) Due to unbundling-related constraints, potential operators from the group of electricity transport system and distribution system operators face lacking permission to operate production plants. Moreover, ownership remains forbidden for them. The same applies to natural gas transport system operators. The case is less clear for natural gas distribution system operators, where explicit regulation is missing. (4) It is finally analyzed if the production of green hydrogen is currently supported in competition with fossil hydrogen production, not only by the legal framework but also by the National Hydrogen Strategy and the Amendment of the Renewable Energies Act. It can be concluded that in recent amendments of German energy legislation, regulatory support for green hydrogen in Germany was found. The latest legislation has clarified crucial points concerning the ownership and operation of electrolyzers and the treatment of green hydrogen as a renewable energy carrier.