Heating Furnace Research Articles

Effect of electric current on microstructure and texture evolution of the Ti2AlNb alloy during hot deformation

In this study, the stress-strain behavior of sintered Ti2AlNb alloy obtained at the temperatures of 980 °C and 1080 °C with a strain rate of 0.5 s−1 was investigated using compression tests under furnace heating and current heating. When deformed at 980 °C, the B2 phase texture orientation all exhibited <001>//ND and <101>//ND during current-assisted hot compression (CAHC) and furnace hot compression (FHC). With the deformation temperature increased to 1080 °C, the texture <001>//ND gradually moved towards the <111> texture direction during CAHC. The results were ascribed to the different microstructure evolution that dynamic globularization and DRX by electric current. It indicated that the current promoted the spheroidization of the O phase which did not change the texture orientation. However, as the temperature increased to 1080 °C, the current promoted dynamic recrystallization which resulted in big changes in B2 phase texture orientation. The current promoted the spheroidization of lath by accelerating the phase transformation of O→B2. The current affected the dynamic recrystallization (DRX) mechanisms by promoting the transformation of low-angle grain boundaries (LAGBs) into high-angle grain boundaries (HAGBs) through continuous absorption of dislocations. The true stain-stress curves indicated the reduction of the deformation resistance and enhancement of the deformability of the Ti2AlNb alloy, which was closely related to the microstructure evolution.

A combined theoretical, computational, and experimental investigation to evaluate performance of suitable thermocouple for microwave processing

Accurate temperature measurement during any microwave processing of material is a contentious issue. While thermocouples are routinely utilized in conventional heat furnaces, their presence in microwave cavities may cause complications such as localized distortion of electromagnetic field, heat dissipation, thermal instabilities, microwave breakdown, and significant inaccuracies in temperature measurement. Therefore, in the present investigation thermocouple effects are discussed by providing the results of temperature estimation by various thermocouples for microwave cladding systems. The present study theoretically and experimentally explored the impact of multiple thermocouples on temperature measurements during microwave heating. COMSOL simulation models were developed to explore microwave and thermocouple interaction during microwave heating. Simulation models were used to assess the effects of the microwave power intensity, thermocouple orientation, and geometry on temperature measurement. The investigation outcomes can be utilized as a guide for selecting appropriate thermocouples in the applications of microwave cladding and other microwave-based manufacturing processes.

Drying kinetics and mathematical modeling of seeds of two mango varieties at different temperatures and with different pretreatments

AbstractIncreasing global waste generation is not only a threat but also an opportunity to address energy insecurity and pollution using green valorization techniques. However, this requires pretreatment of waste and byproducts and optimization of drying to obtain high‐quality biofuels. Hence, this study aims to analyze the performance of currently used drying models, the influence of different drying temperatures, drying time, and seed pretreatment on the drying kinetics of two varieties of mango seed. Accordingly, whole seeds and crushed seeds were exposed to five drying temperatures (313–353 K) in a heating furnace. Weight loss was recorded systematically, converted into moisture ratio, and then fitted to four semitheoretical mathematical models, namely: (i) Lewis, (ii) Henderson and Pabis, (iii) Page, and (iv) Avhad and Marchetti models. The fitness of these models was compared using statistical parameters, such as R2, X2, root mean square error (RMSE), mean bias error (MBE), and mean absolute error (MAE). The results showed that seed pretreatment and increasing the drying temperature led to an increase in the rate of moisture evaporation and reduced the time required for drying. Among all models, the Avhad and Marchetti model provided higher R2 values of 0.9994 and 0.9991 for local and hybrid mango at 313 K, and 0.9977, and 0.9970 for local and hybrid crushed mango seeds at 353 K and 313 K, respectively; hence, it showed the best performance. The activation energy (Ea) showed a slight differences for both varieties of mango seed and among pretreatments in all mathematical models. The mean Ea values for local and hybrid mango seeds were 41.18 kJ mol−1 and 46.21 kJ mol−1, respectively. For whole and crushed local and hybrid mango varieties, the mean Ea values were 31.37 kJ mol−1, 40.80 kJ mol−1, 50.99 kJ mol−1, and 51.61 kJ mol−1. The likely reason for this variation might be differences in variety, chemical composition, growing conditions, and cellular structure of the seed varieties.

Metallographic characterization of metallic heat shields, accidentally precipitation-hardened with tripled soaking time

Abstract Heat treatment (HT) problems, or the lack of necessary HT, are a regular topic of discussion in the papers published in this section Failure Analysis of Practical Metallography. In this present contribution, a case study is presented that shows how an erroneous furnace run almost caused the scrapping of an entire engine set of Metallic Heat Shields (MHS) of a heavy-duty gas turbine engine. The authors readily admit that the subject components did not fail. They were not even put in engine service yet. That means that this case study does not describe a failure in the original sense of the word. However, from a metallurgical point of view, it is still an interesting case that shows that without proper scrutiny during metallurgical investigation in the laboratory, considerable economic loss could have resulted from a simple fabrication problem, that involved a malfunctioning control system of a heat treatment furnace. It was concluded from the metallurgical investigation that is the subject of this contribution that an almost tripled soaking time during aging, i. e., precipitation hardening, of an entire engine set of MHS did not cause any microstructural alterations that could have detrimentally affected mechanical properties of the subject components.

Technoeconomic Analysis of Oxygen-Supported Combined Systems for Recovering Waste Heat in an Iron-Steel Facility

In this study, it is proposed to generate electrical energy by recovering the waste heat of an annealing furnace (AF) in an iron and steel plant using combined cycles such as steam Rankine cycle (SRC), organic Rankine cycle (ORC), Kalina cycle (KC) and transcritical CO2 cycle (t-CO2). Instead of releasing the waste heat into the atmosphere, the waste heat recovery system (WHRS) discharges the waste heat into the plant’s low-temperature oxygen line for the first time, achieving a lower temperature and pressure in the condenser than conventional systems. The waste heat of the flue gas (FG) with a temperature of 1093.15 K from the reheat furnace was evaluated using four different cycles. To maximize power generation, the SRC input temperature of the proposed system was studied parametrically. The cycles were analyzed based on thermal efficiency and net output power. The difference in SRC inlet temperature is 221.6 K for maximum power output. The proposed system currently has a thermal efficiency and total power output of 0.19 and 596.6 kW, respectively. As an environmental impact, an emission reduction potential of 23.16 tons/day was achieved. In addition, the minimum power generation cost of the proposed system is $0.1972 per kWh.

The Effect of Carbide Concentration at Grain Boundaries on Thermal Stresses in Castings for Heat Treatment Furnace Tooling

Austenitic Fe-Ni-Cr alloys are commonly used for the production of castings intended for high-temperature applications. One area where Fe-Ni-Cr castings are widely used is the equipment for heat treatment furnaces. Despite the good heat resistance properties of the materials used for the castings, they tend to develop cracks and deformations over time due to cyclic temperature changes experienced under high temperature operating conditions. In the case of carburizing furnace equipment, thermal stresses induced by the temperature gradient in each operating cycle on rapidly cooled elements have a significant influence on the progressive fatigue changes. In the carburized subsurface zone, also the different thermal expansion of the matrix and non-metallic precipitates plays a significant role in stress distribution. This article presents the results of analyses of thermal stresses in the surface and subsurface layer of carburized alloy during cooling, taking into account the simultaneous effect of both mentioned stress sources. The basis for the stress analyzes were the temperature distribution in the cross-section of the cooled element as a function cooling time, determined numerically using FEM. These distributions were taken as the thermal load of the element. The study presents the results of analyses on the influence of carbide concentration increase on stress distribution changes caused by the temperature gradient. The simultaneous consideration of both thermal stress sources, i.e. temperature gradient and different thermal expansions of phases, allowed for obtaining qualitatively closer results than analyzing the stress sources independently

Decoupled Crystallization and Particle Growth of BiVO4 via Rapid Thermal Process for Enhanced Charge Separation

AbstractBiVO4 is one of the most promising candidates for photoelectrochemical water oxidation. However, the poor crystallinity and short hole diffusion length limit its charge separation. One bottleneck stems from the contradiction between high crystallinity and small particles via conventional furnace heating processes. This paper describes the design and fabrication of BiVO4 photoanodes via rapid thermal process (RTP), rather than furnace heating, to decouple the constraints between nucleation, crystallization, and growth processes of BiVO4. The higher heating ramp rate of RTP compared with furnace heating promotes the fast diffusion of reactant molecules, which elevates the nucleation rate above the particle growth rate of BiVO4, leading to small particles with high crystallinity. Moreover, the ultra‐high heating temperature makes it possible to crystallize the small BiVO4 particle within a short time. Thus, a high crystallinity can be obtained for the RTP‐treated BiVO4 while maintaining small particle size, achieving a charge separation efficiency of up to 82%, 30% higher than that of furnace‐treated BiVO4 photoanode.

Effect of temperature on oxidation during boriding of Ni-Hard 4

Abstract Ni-Hard 4, also known as white cast iron, is widely used in many applications that demand high mechanical strength. This material is recognized for its ability to withstand challenging conditions. In this study, surface modification processes, particularly boriding, were carried out on the material. Boriding is considered an effective process for enhancing the mechanical strength of a surface. While there are various methods for performing boriding, the pack-boriding method was chosen for this study. This method was applied in a typical heat treatment furnace. Ni-Hard 4 specimens were subjected to different combinations of temperature (1000–1200 °C) and 4 h duration, resulting in a total of three distinct samples. Subsequently, the microstructure, hardness, and chemical composition of the boride layers formed on the material’s surface were meticulously examined. As a result of the detailed analysis, it was determined that if the boriding process was carried out in a furnace without controlled atmosphere, high temperature oxidation started on the surface of Ni-Hard 4, and in this case it increased in parallel with the increase in temperature.

Parthenium hysterophorus derived nanostructures as an efficient carbocatalyst for the electrochemical sensing of mercury(II) ions

The sustainable utilization of resources motivate us to create eco-friendly processes for synthesizing novel carbon nanomaterials from waste biomass by minimizing chemical usage and reducing energy demands. By keeping sustainability as a prime focus in the present work, we have made the effective management of Parthenium weeds by converting them into carbon-based nanomaterial through hydrothermal treatment followed by heating in a tube furnace under the nitrogen atmosphere. The XPS studies confirm the natural presence of nitrogen and oxygen-containing functional groups in the biomass-derived carbon. The nanostructure has adopted a layered two-dimensional structure, clearly indicated through HRTEM images. Further, the nanomaterials are analyzed for their ability towards the electrochemical detection of mercury, with a detection limit of 6.17 μM, while the limit of quantification and sensitivity was found to be 18.7 μM and 0.4723 μM μA−1 cm−2, respectively. The obtained two-dimensional architecture has increased the surface area, while the nitrogen and oxygen functional groups act as an active site for sensing the mercury ions. This study will open a new door for developing metal-free catalysts through a green and sustainable approach by recycling and utilization of waste biomass.

A Study on the Effects of Hob Temperature on the Rock-Breaking Characteristics of Sandstone Strata

To explore the effect of hob temperature on the rock-breaking characteristics of full-section tunnel boring machines (TBMs) in sandstone strata, high-temperature furnace heating experiments of sandstone and physical and mechanical experiments at room temperature and high temperatures were conducted to obtain the mechanical properties of sandstone at different temperatures. The mechanical properties at different temperatures were calibrated using PFC3D to obtain micro-mechanical and thermodynamic parameters and establish a rock-breaking model. The orthogonal experiments were used to establish the simulation experiments of rock breaking under different temperatures, confining pressure conditions, knife tip distances, and penetration degrees. The results show that the hob tip force is gradually increasing with an increase in the confining pressure. When below 600 °C, there is little temperature transfer from particle to particle as the temperature increases. At this time, with the two sides of the rock slag flaking, the hob knife tip force is the first to reduce. After 600 °C, with the expansion of the rock extrusion hob, the temperature rises on both sides; at this time, the hob tip force also increased. The hob tip force is minimal at a tip distance of 70 mm and an S/P of 14. As the surrounding pressure increases, the rock-breaking efficiency of the hobber decreases. The highest rock-breaking efficiency is achieved at 25 °C and 600 °C. The rock-breaking efficiency is highest when the knife tip distance is designed to be 70 mm, and when the S/P is 14. The three-dimensional constitutive analysis of rock-breaking particles showed that the increment caused by the hob temperature is mainly distributed in the normal force direction in the surrounding rock without any confining pressure, and the increment caused by the hob temperature exposed to the confining pressure occurs in all directions.

Energy-Technology Indicators of a Multi-Drum Electric Furnace for Firing Vermiculite Concentrates

The design and working process of a new electric drum furnace for heat treatment of vermiculite concentrates and conglomerates, as well as other bulk porous materials based on a silicate binder, are considered. The electric drum furnace is devoid of the disadvantages inherent in its predecessors – furnaces with a movable hearth platform: there are no oscillating elements, dynamic effects do not occur, and there is also no resonant mode of operation, since the working drums perform rotational motion with a constant angular velocity. Using the example of a six-drum furnace, the volumes of processed material located in the firing spaces are calculated, and the second and hourly productivity of the furnace (10 m3/h or 0.0029 m3/s) are determined. The temperature of the heating elements (1167 K) was calculated, the electric power of the furnace (95.2 kW) and the specific energy intensity of the firing process of vermiculite concentrate, with a dimension of 4 mm (0.004 m) from the raw materials of the Kovdorsky deposit – 44.2 MJ/m3, which makes the furnaces of the new design competitively capable, were determined.

Development of a method for discrete-continuous inverting control of pressure control circuit inside a heating furnace

Development of a method for discrete-continuous inverting control of pressure control circuit inside a heating furnace

Experimental Study on Hollow Steel Sections Under Elevated Temperature

Structures known as modular buildings are made in factories and then moved to construction sites, where they are assembled. The efficacy of modular structures under many uncertainties has to be thoroughly investigated as demand rises; fire is one such uncertainty. The purpose of this study is to ascertain how high temperature affects the components of modular constructions. In the current study, hollow steel columns and beams were taken into account as components of a modular construction. Using ABAQUS, several situations were examined depending on the span length to determine the important locations of the members. Experimental research was conducted on the critical regions identified by the analysis, and the results were contrasted with those of the analysis. A high-temperature localized heating furnace was used for the experimental testing. The findings demonstrated that for spans of 250 mm and 500 mm, the central area of the beams was essential, and the load-carrying capacity was six times less than that of heating at the extremities of the beams. Similar to the beams, columns exhibited less fluctuation than the beams and were weaker in the bottom area when exposed to high temperature. When compared to other places, the capacity was reduced by 1.1 times, and in Case 1, the capacity reduction with regard to loading was 1.68 times greater. Doi: 10.28991/CEJ-2024-010-03-014 Full Text: PDF

Effect of Weight Percent Mg and Heat Treatment on the Mechanical Properties of Al10Si Aluminum Alloy Casting Products Car Chassis Materials

Innovation in the automotive field is now growing rapidly. New materials are considered to be incorporated in automotive design if they have economic and vehicle performance benefits. This research investigates the change of the Magnesium (Mg) addition and heat treatment to the mechanical properties and microstructure of the car chassis prototype with Al10Si Aluminum alloy base material. The process of casting using the High-Pressure Die Casting method. Variation of Mg (3, 4, 5 wt%) to increase the strength of mechanical properties of Al10Si aluminum alloy material. In the casting process, the first Al10Si heated up to 690°C. Mg is incorporated into the heating furnace, then stirred by a mechanical stirrer. Stirring speed of 90 rpm and stirring time of 120 seconds. After it has poured into the mold, the casting temperature is 740°C. Then cools the room to room temperature 39°C. Then performed, heat treatment, using the method of age hardening and artificial aging. The test results prove that the hardening heat treatment makes the grain size smaller. Small grain size, then increase the strength of the material with the addition of Mg elements.

Polymer Metallization by Cold Spray Deposition of Polyamide-Copper Composite Coatings

Cold spray metallization of polymers is a promising surface engineering technique that enables the deposition of metal coatings onto polymer substrates at low process temperatures, resulting in improved surface properties, thus enhanced functionality of the polymeric material. However, deposition of well-adhering metallic coatings without causing surface damage to the polymer substrate is still a challenge. In this work, copper-polyamide composite coatings with different copper concentrations between 30 and 75 vol.% in the starting powders were deposited on polyamide substrates using a low-pressure cold spray system with two nozzle geometries of short and long diverging sections. The spray parameters were first developed for the deposition of polyamide powder (at gas temperature of 260 °C and gas pressures ranging from 0.41 to 1.37 MPa), and then used to spray the composite powder mixtures where the polyamide particles were acting as a binder for copper particles. Inflight and impact particle characteristics (velocity and temperature) of the polyamide powder were simulated to better understand the deposition properties. Considering that the selected conditions were suboptimal for the deposition of copper particles, no surface damage was caused as no penetration of the copper particles into the polymer substrate occurred. The results show that increasing the copper content in the powder mixtures significantly improved the resulting coating uniformity and the retained copper content. In addition, the coating deposited by spraying the powder mixture with a higher copper content of 75 vol.% and using the longer nozzle yielded the highest cohesion strength. To further improve coatings cohesion, two post-spray processing methods of furnace heating and hot pressing were used, and the effect of each process on coatings properties was investigated.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Given name: [Kintak Raymond] Last name [Yu]. Also, kindly confirm the details in the metadata are correct.The author names are now correct: Kintak Raymond given name and Yu last nameAll other details are corrects

Enabling Heteroatom Doping of Flexible MXene Film in Seconds: A Microwave‐Induced Targeted Thermal‐Shock Method

AbstractHeteroatom doping can efficiently tailor the physicochemical properties of 2D MXene materials for enhancing the energy storage performance. However, in mostly applied doping strategies, the wet chemistry method typically suffers tedious separation and abstersion process while the solid‐phase thermal strategy (traditional furnace heating) employed long‐time （several hours） high‐temperature treatment may cause degradation of MXene. In this work, a universal, energy efficient and environmental‐friendly strategy is reported to realize the heteroatom doping of MXene within seconds by microwave‐induced targeted thermal shock. The MXene film can self‐heat to &gt;800 °C within seconds followed by generating dazzling plasma under microwave field. The high temperature combined with plasma create a localized ultrahigh‐energy environment in MXenes, which promotes the rapid decomposition of preloaded dopant precursors and lattice/surface functional group substitutions between dopant atoms and MXene. The resulted nitrogen (N) and sulfur (S) co‐doped MXene showed significantly improved capacity and performance stability under deformations. Compared with the traditional furnace heating, the targeted heating strategy have significantly higher energy and time efficiencies and reduced carbon footprint. In addition, this method can be readily extended to various element doping of MXene. The microwave‐induced targeted thermal‐shock represents a general and efficient strategy for the fast heteroatom doping of MXene.

Kinetic modeling of a Claus reaction furnace and waste heat boiler: Effects of H2S/CO2 and H2S/H2O ratio on the production of hazardous gases in an industrial sulfur recovery unit

In this study, the reaction furnace (RF) and waste heat boiler (WHB) were modeled using a kinetic model developed from key reactions to determine how the input feed in the various acid gas scenarios affects the Sulfur Recovery Unit's (SRU's) thermal stage for industrial application. The modeling results showed that, while keeping other parameters constant, a decrease in the H2S/CO2 and H2S/H2O ratios leads to an increase in the production of hazardous gases such as CO, SO2, and COS in the Waste Heat Boiler (WHB). Consequently, this leads to a decrease in the efficiency of the Sulfur Recovery Unit (SRU). When the temperature profile is altered, the Claus reaction pathway changes unfavorably, consequently affecting the overall efficiency of the Claus process. The accuracy of the kinetic model decreases as the acid gas becomes more dilute, significantly impacting the temperature profile. The accuracy of these results was confirmed through industrial data spanning from typical acid gas to sweet gas, with a Mean Absolute Percentage Error (MAPE) ranging from 26.18 to 47.37.

Coherent Evaluation of Energy Efficiency for Microwave Catalytic Reactors Based on Reaction Equilibrium

AbstractMicrowave‐driven catalytic processes have attracted the attention of many researchers and industries as these processes are powerful strategies for use in industrial electrification. However, undetectable hot spots inside the catalyst bed can be misleading in terms of the deceptive effects of microwaves on acceleration of catalytic reactions because of the lack of physicochemical knowledge about these processes. In this paper, the hot spots temperatures were estimated based on catalytic ammonia (NH3) synthesis/decomposition equilibrium. The reaction temperature estimated from the chemical equilibrium was more than 100 °C higher than the catalyst bed surface temperature measured with an infrared thermometer under microwave irradiation. Assuming a formation of very steep local high temperature fields, rigorous kinetic analysis led to an estimate that the active site fraction which reaches the high temperature was only about 10 % of total sites. Compared with a resistivity heating furnace, the energy input was reduced by more than 85 % under microwave irradiation. The temperature estimated by the chemical equilibrium was almost corresponding to the temperature estimated by an oscillation of extended X‐ray absorption fine structure recorded under microwave irradiation. This paper presents a proposal for a method to estimate hot spots based on thermodynamic equilibrium, yielding a quantitative evaluation of energy consumption reduction caused by microwaves.

Influence of state of charge inconsistency on electrical performance and thermal runaway characteristics in 2 serials 1 parallel lithium‐ion battery pack

AbstractLithium‐ion batteries (LIBs) are connected in series during use. State of charge (SOC) difference between two batteries will exist after charging/discharging owing to the capacity or resistance difference between them. This is also seen as SOC inconsistency. SOC inconsistency may cause battery electrical abuse. In this manuscript, a battery testing system, scanning electron microscope, heat furnace, and so on were employed to investigate the influence of SOC inconsistency on electrical performance and thermal runaway (TR) characteristics in 2 serials 1 parallel (2S1P) LIB pack after cycling. The results indicated that the cell with higher SOC in an inconsistent 2S1P pack was overcharged to 4.63 V during first charging, and the cell with lower SOC was over‐discharged to 1.90 V during first discharging. The cell with higher SOC became both overcharged and over‐discharged gradually with cycles. The cell with lower SOC became neither overcharged nor over‐discharged gradually. The electrical performance and TR characteristics of the cell with higher SOC became worse, while that of the cell with lower SOC did not change obviously. The state of health for cells with higher SOC decreased from 100% to 58% after 80 cycles. The time interval between current interrupt device activation and onset temperature of TR for cells with higher SOC was reduced by 183 s, and the maximum surface temperature increased by 34°C.

Development of Manufacturing Process for High-Chromium Steel Large Welding Roll

Due to the operating conditions of weld and calibrating rolls used in the production processes of large electric-welded pipes, their material is subject to stringent wear and abrasion resistance requirements at high temperatures. The limited capabilities of conventional Cr-Mn-Ni tool steels and open die forging technologies with heat treatment processes do not provide the required performance properties for large welded rolls. Therefore, the material of the product was replaced with Cr12MoV high-chromium steel. This required identifying the formation patterns of the fine grain structure of high-chromium steel in order to adjust the production technology with adaptation to the unique conditions and equipment (12.5 MN hydraulic forging press, heating and thermal furnaces) of the forging shop. The technology was offered, which included the development of modes from heating to heat treatment with intermediate two-stage forging from Cr12MoV steel ingots in two sets of combined dies. At the first stage, deformation with a low reduction ratio ε = 5% and a relative feed rate of 0.4 per pass was provided to break and refine the carbide mesh, and at the second stage, intense deformation with a reduction ratio ε = 15% was performed. Further practical application has shown that the durability of weld rolls made from the new material increases by 20–30%.