Heating Tests Research Articles

Analysis of Temperature and Stress Distribution on the Bond Properties of Hybrid Tailored Formed Components

Processing of hybrid materials is particularly challenging due to the different physical properties and requires extensive knowledge to produce defect‐free components. When serially combining steel and aluminum through rotary friction welding and subsequent cup backward extrusion in Tailored Forming, the strongly different yield stresses are a decisive factor. The following study analyzes the temperature and stress distribution after the compensatory heating step with additional cooling and during cup backward extrusion within a preform of a hybrid hollow shaft using experimental heating tests and finite element simulations. The influence on the bond strength is quantified by uniaxial tensile tests along the interface. Compared to uncooled samples, local cooled samples exhibit higher compressive stresses in the joining zone and hence higher forming resistance due to higher temperature gradients. Therefore, delamination and cracks can be prevented. While areas at the edge or in the center indicate reduced strengths overall, areas with high surface enlargement do not fail in the joining zone, but in the base material of the aluminum. To further enhance process stability and process control measures, a preliminary concept for the implicit determination of component temperatures using integrated sensor systems on the handling system is presented.

Damp‐Heat–Induced Degradation of Lightweight Silicon Heterojunction Solar Modules With Different Transparent Conductive Oxide Layers

ABSTRACTLightweight photovoltaic applications are essential for diversifying the solar energy supply. This opens up vast new scenarios for solar modules and significantly boosts the capacity of renewable energy. To ensure high efficiency and stability of the solar modules, several challenges need to be overcome. Degradation due to elevated temperature and/or humidity is a critical concern for silicon heterojunction (SHJ) solar modules. Here, we investigated the stability and degradation mechanism of encapsulated cells with lightweight configurations where the cells are based on three different types of transparent‐conductive oxide (TCO): indium tin oxide (ITO), aluminum‐doped zinc oxide (AZO), and a combination of ITO/AZO/ITO under humid and thermal environmental conditions. A damp heat (DH) test at a temperature of 85°C and relative humidity (RH) of 85% was performed on lightweight modules for 1000 h. Our results show that AZO is the most susceptible to DH degradation. The AZO film was damaged by the combined effects of moisture ingress and delamination of the interconnection foil, resulting in a decrease in the conductivity of the AZO film, leading to a dramatic increase in Rs and a decrease in FF of the modules. Consequently, moisture has a greater chance of percolating through the damaged AZO layer into the a‐Si:H passivation layer, causing passivation degradation, which leads to an increase in recombination, resulting in a decrease in Voc of the modules. In particular, after capping the AZO film with an ITO film, the efficiency loss of the ITO/AZO/ITO module was significantly reduced. This suggests that the ITO film could be a promising protective capping layer for the AZO‐based solar cells.

Experimental Study on a Solar Energy–Multi-Energy Complementary Heating System for Independent Dwellings in Southern Xinjiang

This study proposes a multi-energy complementary heating system that uses solar energy combined with biomass energy as the main heat source, with electricity as an auxiliary heat source. The system aims to tackle the low efficiency, high energy consumption, and pollution associated with traditional heating methods in rural southern Xinjiang, enhancing performance and productivity. It is designed to operate in five modes based on the region’s climate and building heat load requirements. An experimental platform was set up in eight rural households in Tumushuk City, Xinjiang, where winter heating tests were conducted. The goal of this study was to analyze the economic and environmental benefits of the system. The results showed that the energy utilization efficiencies of the five modes were 56.84%, 74.34%, 70.1%, 63.13%, and 59.68%. The corresponding CO2 emissions were 3.56 kg/d, 45.09 kg/d, 105.75 kg/d, 30.97 kg/d, and 76.79 kg/d. The environmental and economic costs for each mode were 0.0493 USD/d, 0.6398 USD/d, 1.5029 USD/d, 0.4384 USD/d, and 1.0905 USD/d. It is clear that as an auxiliary heat source, biomass energy is more beneficial than electricity. All five modes maintained indoor temperatures of 18 °C or higher, meeting winter heating needs in cold regions. The results of this study provide important data support for the promotion and application of solar and biomass heating systems in the rural areas of southern Xinjiang and also provide valuable references for solving the problem of decentralized heating in rural areas.

Interface Mechanism of Promoting Low-Rank Coal Flotation by Characteristic Groups in Hydrophilic Moieties of Cationic-Anionic Surfactants.

Flotation is an interfacial process involving gas, liquid, and solid phases, where polar ionic promoters significantly influence both gas-liquid and solid-liquid interfaces during low-rank coal (LRC) flotation. This study examines how the structures of hydrophilic groups in cation-anion mixed promoters affect the interfacial flotation performance of LRC pulp using flotation tests, surface tension tests, wetting heat tests, and molecular dynamics simulations. Results indicate that cation-anion mixed promoters enhance the LRC floatability to varying degrees. When the cationic hydrophilic head contains a benzyl group and the anionic head contains an ethoxy group, both the floatability and selectivity improve. These mixed promoters exhibit superior surface activity compared to single ionic solutions, particularly with ethoxy-containing anions, which demonstrate an increased density and viscoelasticity at the gas-liquid interface. The combination of a benzyl cation and an ethoxy anion results in dense adsorption at the solid-liquid interface, maximizing wettability differences between organic matter and mineral surfaces. This is attributed to hydrogen bonds and π-π interactions between the promoter and the coal surface, enhancing adsorption selectivity. Hydrophobic chains shield polar sites on the LRC surface, promoting water molecule diffusion and providing sites for nonpolar oil molecule adsorption, thereby improving LRC flotation performance.

Source Material Design for Realizing >50% Indium-Saving Transparent Electrode toward Sustainable Development of Silicon Heterojunction Solar Cells.

Indium (In) reduction is a hot topic in transparent conductive oxide (TCO) research. So far, most strategies have been focused on reducing the layer thickness of In-based TCO films and exploring In-free TCOs. However, no promising industrial solution has been obtained yet. In our work, we adopt the emerging reactive plasma deposition (RPD) approach and provide our In-reduced solution by directly reducing the In content from the source material. We designed the indium zinc oxide (IZO) target with a composition of Zn3In2O6 (i.e., (ZnO)3·In2O3). Density functional theory (DFT) calculation shows that the introduction of a large amount of ZnO significantly perturbs the conduction band of the In2O3 host, resulting in a limitation of exploring high-mobility IZO films. For TCOs used in solar cell application, low resistivity with high carrier mobility is required. Via RPD process optimization, we obtained the minimal resistivity value of 6.08 × 10-4 Ω·cm, which is comparable to our lab-standard tin-doped indium oxide (ITO) film. The corresponding electron mobility and carrier concentration are 31 cm2 V-1 s-1 and 3.37 × 1020 cm-3, respectively. Our IZO film is in an amorphous state. The optical band gap is ∼3.6 eV. X-ray photoelectron spectroscopy (XPS) data show that the film composition is In:Zn:O = 21.60:28.75:49.65 (at. %). Damp heat tests show strong stability of our IZO film, and no aging effects have been observed. Furthermore, we demonstrated wafer-scale silicon heterojunction (SHJ) solar cells with IZO films. As compared with our reference hydrogenated cerium-doped indium oxide (ICO)-based solar cells, the IZO-based devices show even higher fill factor parameters. Our amorphous state stable In-reduced IZO film could find versatile application in the sustainable development of temperature-sensitive devices such as SHJ and perovskite/silicon tandem solar cells, as well as flexible OLEDs.

Study on Reliability of Field-Aged Photovoltaic Connectors

The paper presents the reliability study on field-aged photovoltaic connectors of different makes characterized by diverse climatic conditions with 2 to 10 years of operational life. A series of tests conforming to IEC 62852 conducted on field-aged connectors and control samples. The objective is to elucidate the mechanisms of aging and evaluate reliability of connectors, identify failure modes, potential hazards, changes in electrical and mechanical performance because of longstanding exposure to environmental and operational stresses. Field survey and testing reveal lack of awareness of workmanship and maintenance. Laboratory testing reveals connector less than 6 years of life shows low contact resistance and remain stable or have marginal linear increase after thermal and damp heat testing. Samples with life of 6 years or more from extreme climatic regions show high contact resistance with nonlinear pattern increasing to 300% in the thermal cycle and up to 600% in damp heat test. In SEM fretting was observed with high contact resistance with marginal polymer deterioration

Fracture Surface Morphology of the Impact-Loaded Tempered Spring Steels

The objective of this study is to evaluate the surface morphology of 51CrV4 and 55Cr3 spring steels after undergoing tempering and testing at various temperatures, with a focus on dynamic fracture behavior. For this purpose, 51CrV4 and 55Cr3 spring steel samples were normalized at 870°C for 30 minutes for the same initial microstructure. Then, samples were austenitized at 870°C for 30 minutes and rapidly quenched in oil following tempering at 300°C-525°C range for 2 hours. Tensile tests at room temperature were performed to identify tensile properties, especially percent elongation values. CharpyV notched impact tests were carried out at -40, 0, room temperature, and +80°C testing temperatures to examine the fracture surface morphology of steels according to heat treatment procedures and testing (environmental) temperature. The fracture surfaces were examined by micro and macro analysis, respectively achieved by a digital camera and a scanning electron microscope (SEM). Mix mode (ductile and brittle) fracture (quasi-cleavage type) was detected for all quenched and tempered steels. Increasing tempering and testing temperatures resulted in more ductile fractures with many dimple formations and fewer secondary cracks.

Application of Active Heating Tests with the Distributed Temperature Sensing to Characterize Flow Dynamics in a Tidal-Influenced Coastal Aquifer

Aquifer storage and recovery have gained attention as a solution that utilizes submarine groundwater discharge (SGD) as a surrogate water resource to alleviate water scarcity and fill the demand gap. Characterizing SGD is crucial for using coastal groundwater and improving understanding of the interaction between continental water and seawater. This study employs fiber-optical distributed temperature sensing (FODTS) and the heat tracer to quantify the groundwater flux in a coastal aquifer in northern Taiwan. The fluxes in different sections along the borehole were estimated from the temperature response caused by the active heating tests and campier groundwater flux under different tidal conditions, providing information on potential water resources for water resource planning and management. According to the active heating tests, the material of the sections with high-temperature response mainly consists of a gravel–sand mixture. Based on the estimations of groundwater fluxes along the well, the sections with low sensitivity of temperature response have low hydraulic conductivity and low groundwater flux. The estimated thermal parameters at the site are consistent with those obtained from the borehole samples in the laboratory tests. The groundwater fluxes in different sections are calculated based on the temperature response observed from the FODTS. The groundwater fluxes along the well vary between 0.02 and 1.77 m/day. There are considerable differences between the estimated fluxes during the tidal cycle in a heterogeneous coastal aquifer, indicating the high uncertainty of estimated SGD along coastlines.

Heterogeneous Amine with Polycyclic‐Aromatics‐Modified Hole Transport Material for Efficient and Operationally Durable Perovskite Solar Cells

AbstractAchieving efficient perovskite solar cells (PSCs) with high operational durability is a challenging task. Here, by exploiting the heterogeneous amine strategy at the molecular level, a novel spirobifluorene derivative bearing methoxynaphthalene and 9,9‐dimethylfluorene heterogeneous amine peripheral groups (N2,N2′,N7,N7′‐tetrakis(9,9‐dimethyl‐9H‐fluoren‐2‐yl)‐N2,N2′,N7,N7′‐tetrakis(6‐methoxynaphthalen‐2‐yl)‐9,9′‐spirobi[fluorene]‐2,2′,7,7′‐tetraamine, denoted as Spiro‐NADF) as a hole transport material (HTM) is developed to address the efficiency and durability issues of PSCs. Compared with 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl)‐amine‐9,9′‐spirobifluorene, Spiro‐NADF exhibits not only favorable energy level alignment but also a higher glass transition temperature and strong adhesion to perovskite. Moreover, Spiro‐NADF‐based transport layer shows excellent morphological stability in devices against damp heat stress. These advantages reduce voltage loss and suppress perovskite decomposition and ion migration. Consequently, PSCs based on Spiro‐NADF exhibit a champion efficiency of 24.66% with an open‐circuit voltage of 1.19 V. The corresponding cells show greatly enhanced operational durability against harsh environments, retaining over 92% of the initial efficiencies for 500 h aging under a damp heat test (85 °C and 70–90% relative humidity) and illumination under the maximum power point tracking, respectively. This work demonstrates that molecular engineering of HTMs using heterogeneous amines with polycyclic aromatics leaves considerable room for developing efficient and stable PSCs.

Indium Reduction Above 70% in SHJ Solar Cells: Study of the Module Stability

This work focuses on reducing In-based TCO thicknesses to their minimum in SHJ solar cells with the goal to demonstrate the possibility of a drastic reduction of indium consumption in the fabrication process. On the front side, the reduction of the ITO thickness down to 15 nm implies to deposit an additional anti-reflective layer. Three anti-reflective dielectric layers have been studied (SiNx, SiOx and a bilayer SiNx/SiOx) in solar cell and module configurations to maximize the performances and evaluate the module stability under UV exposure. Lower Jsc losses after 120 kWh of UV exposure are measured with the use of thinner ITO layers, in agreement with a lower EQE deterioration in the IR range. The use of SiNx dielectric results in the highest stability under UV and to the best performances after 120 kWh. Following further optimizations of the dielectrics and TCO, the 15 nm of ITO/SiNx option was combined with a thin IMO:H TCO on the rear side. TCO thicknesses down to 30 nm were studied on the rear side resulting in overall indium reduction of 77.2% with very limited efficiency loss at the cell level (below 0.1% absolute after light-soaking). Module reliability of these very low indium content solar cells was studied under UV and damp heat treatments highlighting lower degradations than reference cells for UV and promising results after damp heat test.

Superelastic behavior of novel Ni–Ti–Co shape memory alloys for seismic applications

Abstract Ni–Ti–Co is a new shape memory alloy (SMA) composition that has a higher strength and a lower superelastic temperature range than the traditional binary Ni–Ti SMA composition. In this paper, the superelastic properties of Ni–Ti–Co bars that are important for seismic applications were studied and compared with those of Ni–Ti bars. The superelastic behavior, strength, strain recovery, low-cycle fatigue characteristics, and fracture strains of Ni–Ti–Co and Ni–Ti SMA with different heat treatment strategies and testing temperatures from −40 °C to 50 °C were investigated with seismic applications in mind. The effect of low-cycle fatigue loading and temperature variations on the superelasticity degradation of Ni–Ti–Co SMA were evaluated. The results showed that the yield stress of Ni–Ti–Co SMA at room temperature was 1.41–1.74 times that of the Ni–Ti SMA. Ni–Ti–Co SMA exhibited 100% strain recovery when unloaded from 5% strain in a temperature range from −40 °C to room temperature; while at 50 °C, a residual strain of 0.6% was observed when unloaded from 5% strain. For comparison, the Ni–Ti SMA lost superelasticity when the temperature was reduced to 0 °C. When subjected to low-cycle fatigue loading, the stability of the superelastic behavior (maintaining yield stress, energy dissipation and strain recovery) of Ni–Ti–Co SMA at −40 °C was better than that at room temperature and 50 °C. In particular, the superelasticity of Ni–Ti–Co SMA at −40 °C was superior to that of the Ni–Ti SMA at 0 °C. At −40 °C, the Ni–Ti–Co SMA showed almost no loss in yield stress, damping ratio and recovery strain during the first 100 cycles of fatigue loading. Moreover, from 100th to 471st cycle, at which the fracture occurred, the strain recovery of Ni–Ti–Co SMA showed almost no degradation.

Failure analysis of semiconductor bridge component in humid and hot environment

Abstract In order to solve the problem of failure during the storage of semiconductor bridge initiating explosive devices, the alternating humid and heat test of semiconductor bridge component was carried out according to GJB5309.30-2004 test method for initiating explosive devices -part 30: Humid and heat test. The semiconductor bridge component was characterized by means of resistance measurement, microscopic characterization, energy spectrum test, roughness test, etc. The resistance at the wires showed that the failure rate of Sample 1 and Sample 2 were 11% and 88%, respectively after 28 days of alternating humid and heat test, and the resistance of the failed sample at the solder pads did not change. The scanning electron microscope and energy spectrum test results show that there is significant corrosion at the wires end, and the component such as Fe, Co, Ni appeared at the wire end after the humid and heat test. The roughness test results show that the surface roughness of sample 1’s wire is smaller than that of sample 2. These indicate that the failure mode of semiconductor bridge components in humid and heat environments is atmospheric corrosion, and the surface state of the wire affects their failure efficiency.

Mechanical properties of hybrid fibers and nano-silica reinforced concrete during exposure to elevated temperatures

The increasing risk of fire poses a significant threat to the safety of structural concrete. While the mechanical properties of concrete after exposure to elevated temperatures are well-documented, its properties during exposure remain insufficiently understood, posing challenges for effective fire-resistant design of concrete structures. This study aims to address this knowledge gap by investigating the mechanical properties of hybrid fiber and nano-silica (NS)-reinforced concrete (HFNRC) during elevated temperature exposure. Using a novel multi-functional testing apparatus designed for simultaneous heating and mechanical testing, the effects of varying steel fiber volume ratio (SFs, 0-1.5% by volume) and NS dosages (0-1.5% by weight) were examined at temperatures of 200°C (473.15K), 400°C (673.15K), 600°C (873.15K), and 800°C (1073.15K). The experimental results indicate that compressive and flexural strengths initially decreased, then increased, and subsequently decreased again as temperatures rose from 200°C to 800°C, while splitting tensile strength consistently declined. At 800°C, the compressive, splitting tensile and flexural strengths decreased by 63%, 82% and 76%, respectively. Notably, the addition of 1.5% by volume SFs increased the splitting tensile strength by up to 119% at 400°C, providing the greatest improvement among all tested properties. Empirical equations were established to predict the compressive, splitting tensile, and flexural strengths of HFNRC during elevated temperatures. Microstructural analyses using scanning electron microscopy (SEM) and X-ray diffraction (XRD) demonstrated that NS enhances the compactness of HFNRC’s matrix and promotes the formation of calcium silicate hydrate (C-S-H) gel, contributing to improved performance under fire exposure. These findings are relevant to international research focused on enhancing the fire resistance of structural materials and improving the safety of concrete structures globally.

Effect of CO2 wet mineralized steel slag-granulated blast furnace slag composite admixture on mechanical properties and chloride corrosion resistance of mortar

Given the global emphasis on environmental issues, addressing the substantial quantities of steel slag and greenhouse gases produced by the steel industry has garnered significant attention from researchers worldwide. This research investigates the application of wet CO2 mineralization for the treatment of steel slag. The microstructure and phase composition of steel slag are analyzed and compared before and after the mineralization process using SEM, XRD, TG-DTA, and particle size analysis. Composite mineral admixtures were prepared by mixing steel slag and granulated blast furnace slag to replace 50% cement. The study examined the influence of varying quantities of mineralized steel slag in the admixture on the mechanical properties, chloride permeability and autoclaved stability of mortar. The effects were elucidated through the application of SEM, XRD, TG-DTA, FTIR and early hydration heat testing. The results show that a layer of mineralized shell is formed on the surface of steel slag following wet mineralization treatment, which strengthens the mechanical adhesion between cementitious materials. The calcite produced by the mineralization reaction acts as a nucleation agent and micro-aggregate in the cement hydration process, leading to a significant enhancement in the early strength of mortar. When the mineralized steel slag content is below 30%, it positively impacts the strength of mortar. When the content is below 20%, it has little effect on the chloride ion permeability of mortar.

Managing Solvent Complexes to Amplify Ripening Process by Covalent Interaction Driving Force Under External Field for Perovskite Photovoltaic

AbstractUp to now, post‐annealing is most commonly used to post treat the perovskite film to accelerate the ripening process. Nonetheless, the top‐down crystallization mechanism impedes the efficient desolvation of solvent complexes. Thus, residual solvent complexes tend to accumulate at the bottom of the film during the ripening process and deteriorate the device. Here, a new strategy with unique concept is promoted to amplify ripening process of perovskite film, in which a nematic thermotropic liquid crystal (LC) molecular is introduced to facilitate the conversion of solvent complexes by utilizing the liquid crystalline behavior under external field. Upon the concurrent application of thermal and force fields, the covalent interaction between LC and solvent complexes generates a driving force, which promotes upward migration of solvent complexes, thereby facilitating their engagement in the ripening process. In addition, the driving force under external fields assists the flattening of grain boundary grooves. Therefore, film quality is improved efficiently with amplified ripening process and adequately handled buried interface. Based on the positive effects, the devices achieve a champion efficiency of 25.24%, and sustained ≈75% of its initial efficiency level even after undergoing a damp heat test (85 °C/85% RH) for 1400 h.

Improving Resistive Heating, Electrical and Thermal Properties of Graphene-Based Poly(Vinylidene Fluoride) Nanocomposites by Controlled 3D Printing.

This study developed a novel 3D-printable poly(vinylidene fluoride) (PVDF)-based nanocomposite incorporating 6 wt% graphene nanoplatelets (GNPs) with programmable characteristics for resistive heating applications. The results highlighted the significant effect of a controlled printing direction (longitudinal, diagonal, and transverse) on the electrical, thermal, Joule heating, and thermo-resistive properties of the printed structures. The 6 wt% GNP/PVDF nanocomposite exhibited a high electrical conductivity of 112 S·m-1 when printed in a longitudinal direction, which decreased significantly in other directions. The Joule heating tests confirmed the material's efficiency in resistive heating, with the maximum temperature reaching up to 65 °C under an applied low voltage of 2 V at a raster angle of printing of 0°, while the heating Tmax decreased stepwise with 10 °C at the 45° and the 90° printing directions. The repeatability of the Joule heating performance was verified through multiple heating and cooling cycles, demonstrating consistent maximum temperatures across several tests. The effect of sample thickness, controlled by the number of printed layers, was investigated, and the results underscore the advantages of programmable 3D printing orientation in thin layers for enhanced thermal stability, tailored electrical conductivity, and efficient Joule heating capabilities of 6 wt% GNP/PVDF composites, positioning them as promising candidates for next-generation 3D-printed electronic devices and self-heating applications.

Comparative study of the stabilizing behavior of organoclays in Pickering emulsion

Pickering Emulsions are commonly applied in the pharmaceutical, food, and chemical industries. The use of natural particles as stabilizers provides access to surfactant-free dispersions with reduced toxicity and environmental impact. This work investigates the use of three commercial organoclays (C15A, C10A, and C30B) and hydrophilic sodium montmorillonite (Mt) as stabilizers for Pickering emulsions. Emulsion stability was evaluated through macroscopic and microscopic morphological observations and the emulsion microstructure was characterized by optical microscopy and DLS measurements to assess creaming and coalescence. The influence of different experimental parameters on emulsion stability was evaluated, including organoclay content, emulsification time, emulsification speed, and oil–water ratio. The results showed that emulsions based on C15A exhibit better stability against coalescence as compared to emulsions prepared with the other clays. This was attributed to the wettability of the particles and solution viscosity. Droplet size decreased as emulsification time and stabilizer content increased and reached a minimum value at 1 wt.% of C15A and for emulsification time of 5 min and oil–water ratio O/W (v/v: 50/50). The experimental parameters also impacted emulsion viscosity, increasing it for high clay content and as the stirring speed and emulsification time increased. The results of the heat and cold resistance stability tests indicated that 25 °C represents the optimal storage temperature for the prepared emulsions.

Low sintering shrinkage and high strength of porous mullite–zirconia ceramics: Effect of AlF3 and ZrSi2 contents

AbstractLow‐shrinkage porous mullite–zirconia ceramics were prepared using Al and ZrSi2 as raw materials and AlF3 as the whisker catalyst through foam‐gelcasting and freeze‐drying methods. The oxidation of Al and ZrSi2 combined with the Kirkendall effect and volume expansion was employed to reduce the sintering shrinkage, while the mullitization was promoted by the reaction between AlF3 and extra ZrSi2, and ZrO2 were generated to enhance the compressive strength as the reinforcing phase. The effect of AlF3 and ZrSi2 content on the microstructure and properties of porous mullite‐zirconia were explored. These ceramics exhibited high porosity (73.75%–85.02%) and compressive strength (2.98–17.71 MPa), low shrinkage (0.47%–10.89%) and thermal conductivity (0.228–0.462 W/(m·K)). In particular, the porous mullite–zirconia ceramics with great compressive strength (4.01 MPa) companied with near‐zero shrinkage (0.47%) at the AlF3 content of 15 wt% and extra ZrSi2 content of 20 wt% by introducing the reinforcing phase (ZrO2). Additionally, the temperature difference around 950°C of the porous ceramics during the heating test proved the exceptional application on thermal insulation.

Utilization of hydrogen fuel in reheating furnace and its effect on oxide scale formation of low-carbon steels

The transition from fossil-based fuel to hydrogen combustion in steel reheating furnaces is a possible way to decrease the process-originated CO2 emissions significantly. This potential change alters the furnace gas atmosphere’s composition, impacting the oxide scale formation of the slab surface. Dynamic heating tests are performed for three low-carbon steels using different simulated combustion atmospheres, including natural gas, coke oven gas, and hydrogen combustion in air, and hydrogen combustion in oxygen. Significant differences are found in the oxidation behavior of steel grades in the simulated hydrogen reheating scenario. A steel grade with low Mn content only has an 18% increase in oxidation between methane-air to hydrogen-oxygen methods, while it is 41% for a high Mn and Si steel grade and 65% for a high-Mn steel grade. Thus, in terms of material loss increase by oxidation, the transition of the heating method causes the least problems for the low-Mn steel grade.

Performance Evaluation of a Building Integrated Solar Cooker with Asymmetric Compound Parabolic Concentrator for Indoor Cooking Application

Nigeria faces an acute shortage of conventional energy sources, relying heavily on fossil fuels for cooking, which poses significant health and environmental risks. Solar cookers have emerged as a promising alternative. However, existing solar cookers have limitations, including exposure of users to direct sunlight, low utilization efficiency, and they are predominantly designed for rural and community environments, making them less suitable for urban settlement. This study evaluates the performance of a building-integrated solar cooker (BIS) with an asymmetric compound parabolic concentrator (CPC) for indoor cooking. Experimental tests achieved maximum stagnation temperatures of 126.9°C and 124.8°C on two consecutive days. Water heating tests showed a boiling times of 1 hour 40 minutes and 2 hours for 1.5kg and 2kg of water, respectively. The cooker's figures of merit (F1 and F2) values meet recommended standards, confirming its functionality. Successful cooking of eggs, noodles, and rice demonstrates its potential for sustainable indoor cooking. From the regression analysis, standardized cooking power of 513 W at a temperature difference of 50 OC were estimated using the regression equation and coefficient of determination (R²) were found to be 0.98, exceeding the minimum requirement of 0.75. This indicates a well-fitting regression model for the system. This study addresses the limitations of existing solar cookers highlighting its potential as a viable alternative to conventional energy sources for sustainable indoor cooking and advances solar-thermal technology for urban contexts, aligning with the United Nations Sustainable Development Goals.