Peak Temperature Research Articles

Crustal Thermal Architecture, Structural Reconstructions, Field Relationships, and Geophysical Data Rule Out Deep Structural Burial of the Footwall of the Northern Snake Range Metamorphic Core Complex (Nevada, USA)

AbstractThermobarometry in the Northern Snake Range metamorphic core complex (Nevada, USA) implies pre‐extensional burial of footwall rocks to 21–30 km depths, while geologic field relationships support 7–13 km pre‐extensional depths. This has fueled a 40‐year‐long debate, which has far‐reaching implications for how pressure data are interpreted in orogenic settings. Here, we test published models for deep burial by integrating regional cross‐section reconstructions with new (n = 95) and published (n = 132) peak temperature measurements, field relationships and published geophysical data. Burial of Neoproterozoic‐Cambrian metasedimentary footwall rocks to 21–30 km depths is incompatible with a regional seismic reflection cross‐section that interprets the top of Precambrian crystalline basement at 17–20 km depths. Two reconstructed cross‐sections define 42 km and 50–65 km of displacement on the master detachment fault and demonstrate that the higher displacement ranges (>66–94 km and >76–102 km, respectively) necessary to exhume rocks from 21 to 30 km depths are not possible without spatially overlapping Cambrian rocks preserved in its footwall and hanging wall. The 22°C/km average Late Cretaceous thermal gradient predicted by thermobarometry is incompatible with the 46 ± 10°C/km Late Cretaceous peak thermal gradient that we calculate down to 15–20 km pre‐extensional depths. Field relationships that rule out large‐magnitude shortening invalidate models for deep footwall burial via thrust or reverse faulting. We conclude that there is no scenario for deep burial that is compatible with structural/geophysical constraints, crustal thermal architecture, and field relationships. This necessitates a non‐lithostatic interpretation for pressures from the Northern Snake Range, similar to recent interpretations for other Cordilleran metamorphic core complexes.

Probing pyrolysis conversion of separator from spent lithium-ion batteries: Thermal behavior, kinetics, evolved gas analysis and aspen plus modeling

The exponential growth in the consumption of lithium-ion batteries (LIBs) has resulted in a concomitant increase in the spent LIBs. Multi-component recycling is a highly desirable and beneficial process, yet the separator component remains overlooked. This study examined the thermal behavior, kinetics, thermodynamics, and evolved products of separator pyrolysis in N2 and CO2 atmospheres. Furthermore, the conversion was modeled using Aspen Plus and a sensitivity analysis was conducted to investigate the impact of varying operating conditions. The findings indicated that the whole degradation process could be divided into three stages: below 200 °C, 200–550 °C and 550–900 °C. The evolved products at peak temperatures of 485 °C in N2 and 500 °C in CO2 were composed of olefins and alkanes. The average apparent activation energy values were determined to be 222.78 kJ mol−1 and 159.36 kJ mol−1 in the N2 and CO2 atmospheres, respectively. Thermodynamic analysis indicated that the separator decomposition was an endothermic and non-spontaneous process. Aspen Plus modeling results were in agreement with the experimental data. The sensitivity analysis revealed that an increase in temperature lead to an increased content of lighter compounds (≤C9) and a decrease in the proportion of heavier compounds (>C10) in the pyrolysis products.

Heat transfer performance of regenerative cooling in the presence of supersonic combustion based on two-way decoupling method

As a promising active cooling method for aero engines, regenerative cooling with endothermic hydrocarbon fuel plays an important role in thermal protection systems. However, simply assuming the thermal boundary conditions for the numerical simulation of regenerative cooling as either Dirichlet or Neumann boundary conditions is often unsuitable, as the combustion process exhibits complex three-dimensional (3D) characteristics. We propose a novel multi-step iterative calculation method in this work to simulate the coupled flow and heat transfer between supersonic combustion in the combustor and regenerative cooling outside. The method captures the main features of the supersonic combustion including different shockwave structures, and generates a realistic 3D distribution of heat flux as the boundary condition for the regenerative cooling study. With improved simulation, the result shows that regenerative cooling significantly reduces the peak temperature of the combustor by 58.5% with a mass flow rate of 1 g/s. A local high-temperature region is observed on the coupled wall inside the combustor near the injector, where the flame is primarily concentrated. Increasing the mass flow rate by 100%, from 1 g/s to 2 g/s, leads to a reduction in the maximum wall temperature by up to 15.7%.

Thermal Behaviour, Chemical Composition and Morphological analysis ofCotton Stalk for Efficient Biochar Production

The escalating concern over air pollution from crop stubble burning necessitates responsible biomass disposal or utilisation. In this study, characterisation of cotton stalk was carried out to assess its feasibility for biochar production. The proximate analysis revealed that cotton stalk had moisture content of 8.65%, bulk density of 215.8 kg m-3, volatile matter of 71.65%, and fixed carbon content of 16.03%. The ultimate analysis showed that cotton stalks were predominantly composed of carbon (64.88%), hydrogen (6.58%) , and oxygen (2.55%), with a low (0.66%) nitrogen content . Thermo-gravimetric analysis (TGA) highlighted the pyrolysis process, identifying a peak temperature of approximately 500°C and distinct stages of thermal degradation: moisture loss up to 150°C, hemicellulose decomposition between 200°C and 300°C, cellulose decomposition from 300°C to 400°C, and lignin decomposition from 400°C to 500°C. X-ray diffraction (XRD) analysis confirmed the presence of crystalline cellulose with a diffraction peak at 2θ = 22.5°, indicating significant structural stability during pyrolysis for biochar production. Fourier-transform infrared (FTIR) spectroscopy revealed characteristic peaks associated with cellulose and lignin, underscoring the retention of essential structural components in biochar during biomass conversion. These analyses demonstrated the potential of cotton stalks as a viable feedstock for biochar production, providing a sustainable method for agricultural waste management and soil health improvement.

Observation of Standing Slow Magneto-acoustic Waves in a Flaring Active Region Corona Loop

Intensity fluctuations are frequently observed in different regions and structures of the solar corona. These fluctuations may be caused by magneto-hydrodynamic (MHD) waves in coronal plasma. MHD waves are prime candidates for the dynamics, energy transfer, and anomalous temperature of the solar corona. In this paper, analysis is conducted on intensity and temperature fluctuations along the active region coronal loop (NOAA AR 13599) near solar flares. The intensity and temperature as functions of time and distance along the loop are extracted using images captured by the Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO) space telescope. To observe and comprehend the causes of intensity and temperature fluctuations, after conducting initial processing, and applying spatial and temporal frequency filters to data, enhanced distance-time maps of these variables are drawn. The space-time maps of intensities show standing oscillations at wavelengths of 171, 193, and 211 Å with greater precision and clarity than earlier findings. The amplitude of these standing oscillations (waves) decreases and increases over time. The average values of the oscillation period, damping time, damping quality, projected wavelength, and projected phase speed of standing intensity oscillations are in the range of 15–18 minutes, 24–31 minutes, 1.46″–2″, 132″–134″, and 81–100 km s−1, respectively. Also, the differential emission measure peak temperature values along the loop are found in the range of 0.51–3.98 MK, using six AIA passbands, including 94, 131, 171, 193, 211, and 335 Å. Based on the values of oscillation periods, phase speeds, damping time, and damping quality, it is inferred that the fluctuations in intensity are related to standing slow magneto-acoustic waves with weak damping.

Thermal characteristics of cementitious building materials with carbon and PCM for improved heat storage performance

The thermal properties of cementitious building materials were analyzed by integrating phase change materials (PCMs) and carbon materials to improve their heat storage performance. Four types of carbon materials, namely activated carbon (AC), carbon nanotubes (CNT), exfoliated graphite nanoplatelets (xGnPs), and graphene, were dispersed in PCMs and impregnated into artificial lightweight aggregates via vacuum impregnation to create cement building materials. Various parameters including compressive strength, differential scanning calorimetry (DSC), hydration heat, thermal conductivity, and dynamic heat transfer were evaluated According to the results, the thermal conductivity of PCM was significantly improved by incorporating carbon materials, and the specimen with CNT showed a result of 0.8386 W/m∙K, which is about 20 % higher than that of the specimen without carbon materials. Although the compressive strength decreased with the addition of PCMs, it remained above 20 MPa, thereby ensuring structural integrity. In the dynamic heat transfer test, the carbon/PCM specimen maintained a higher temperature during heat dissipation. It showed a high peak temperature and a time delay of about 2.5 hours during free cooling. The results showed that integrating PCMs and carbon materials into cementitious building materials could effectively improve their thermal performance, potentially saving building energy.

Study the impact of spacer at thermal degradation process of MLI-based insulation in fire condition

To reduce CO2 emissions, energy carriers such as hydrogen are considered to be a solution. Consumption of hydrogen as a fuel meets several limitations such as its low volumetric energy density in gas phase. To tackle this problem, storage as well as transportation in liquified phase is recommended. To be able to handle this component in liquid phase, an efficient thermal insulation e.g., MLI insulation is required. Different studies have been addressed the vulnerability of such insulation against high thermal loads e.g., in an accident engaging fire. Some of research works have highlighted the importance of considering the MLI thermal degradation focusing on its reflective layer. However, limited number of studies addressed the thermal degradation of spacer material and its effect on the overall heat flux.In this study, through systematic experimental measurements, the effect of thermal loads on glass fleece, glass paper as well as polyester spacers are investigated. The results are reported in various temperature and heat flux profiles. Interpreting the temperature profiles revealed that, as the number of spacers in the medium increases, the peak temperature detectable by the temperature sensor on the measurement plate decreases. Each individual spacer contributes to mitigating the radiative energy received by the measurement plate. Stacks of 20–50 spacers (this is the number of layers in commercial MLI systems applied for liquid hydrogen applications) can potentially reduce the thermal radiation by 1–2 orders of magnitude.An empirical correlation to predict a heat flux attenuation factor is proposed, which is useful for further numerical and analytical studies in the temperature range from ambient to 300 °C.

Thermoluminescence and Apollo 17 ANGSA Lunar Samples: NASA's Fifty‐Year Experiment and Prospecting for Cold Traps

AbstractBy placing Apollo 17 regolith samples in a freezer, and storing an equivalent set at room temperature, NASA effectively performed a 50‐year experiment in the kinetics of natural thermoluminescence (TL) of the lunar regolith. We have performed a detailed analysis of the TL characteristics of four regolith samples: a sunlit sample near the landing site (70180), a sample 3 m deep near the landing site (70001), a sample partially shaded by a boulder (72320), and a sample completely shaded by a boulder (76240). We find evidence for a total of eight discrete TL peaks, five apparent in curves for samples in the natural state and seven in samples irradiated in the laboratory at room temperature. For each peak, we suggest values for peak temperatures and the kinetic parameters E (activation energy, i.e. “trap depth,” eV) and s (Arrhenius factor, s−1). The lowest natural TL peak in the continuously shaded sample 76240 dropped in intensity by 60 ± 10% (1976 vs. present room temperature samples) and 43 ± 8% (freezer vs. room temperature samples) over the 50‐year storage period, while sunlit and partially shaded samples (70001, 70180, 72321, 72320) showed no change. These results are consistent with the E and s parameters we determined. The large number of peaks, and the appearance of additional peaks after irradiation at room temperature, and literature data, suggest that glow curve peaks are present in lunar regolith at ∼100 K and their intensity can be used to determine temperature and storage time. Thus, a TL instrument on the Moon could be used to prospect for micro‐cold traps capable of the storage of water and other volatiles.

Photo-thermal and temperature-regulated sodium alginate-g-mPEG/carbon nanotube hybrid fibers with improved tensile strength

Despite the remarkable potential of phase change fibers for energy storage, their practical deployment has been hindered by two crucial challenges: inadequate external thermal stimulation to induce phase transition and leakage of the phase-change material. In this study, we successfully incorporated carbon nanotubes (CNTs) into a solution of sodium alginate grafted polyethylene glycol monomethyl ether (SA-g-mPEG) and utilized wet spinning processing to fabricate CNTs/SA-g-mPEG hybrid fibers with enhanced photo-thermal conversion and robust solid-solid phase change capabilities. Upon exposure to sunlight for merely 60 s, the hybrid fibers achieved a remarkable peak temperature of 40 °C. Upon cessation of sunlight exposure, these fibers demonstrated a gradual release of thermal energy, thereby underlining their exceptional photothermal conversion and temperature regulation capabilities. Furthermore, DSC analysis revealed that, at an optimal grafting ratio of 36.6 %, the hybrid fibers exhibited ΔHc and ΔHm values of 48.23 J/g and 50.83 J/g, respectively. Notably, hybrid fibers with a grafting ratio of 20.2 % demonstrated substantial enhancements in tensile properties, achieving a maximum breaking strength of approximately 2.02 cN/dtex—an impressive 11.3 % increase compared to SA-g-mPEG composite fibers. Our findings suggest that CNTs/SA-g-mPEG hybrid fibers hold immense promise for applications in body heat storage, fabric temperature regulation, and related fields.

Beyond the g-Value: A comparative study of solar control coated glass and spectrally selective glass in terms of building energy efficiency

The thermal efficiency of transparent envelopes is a key factor in building energy consumption and indoor thermal comfort, with the g-value being a critical metric for evaluating these effects. Solar control film glass and low-emissivity (Low-E) glass, recognized for their distinct advantages, are extensively used in construction. However, comprehensive research on their photothermal properties, especially regarding spectral and angular dependencies, remains limited. In this study, a meticulous field experiment was conducted under six distinct conditions during both winter and summer to examine the thermal performance between solar control coated glass (SCCG) and spectrally selective glass (SSG). The results show that, despite having similar heat transfer and solar heat gain coefficients, their indoor peak temperatures can differ by 1.2 °C to 5.6 °C under typical sunny conditions, and variations in cooling and heating energy consumption range from 6.9 % to 14.4 %. Further analysis reveals that the standard g-value overestimates the solar heat gain of SSG by approximately 10 %, with significant discrepancies in the direct transmission heat and secondary heat transfer of 17.8 % and 37.4 %, respectively. In contrast, the standard g-value is more suitable for SCCG, with a measured g-value that is only 1.2 % higher than the standard g-value. The spectral and angular dependencies of both glasses were also compared in this study, and SSG was found to have a strong spectral dependence and a higher angular dependence than SCCG. These findings indicate that SCCG is more beneficial for energy conservation in cold climates when the thermal parameters are identical. Moreover, the research underscores the limitations of current standards and calculation methods for evaluating solar heat gain in transparent envelopes, particularly for glasses with spectral selectivity.

Electrical transport properties of topographically demorphed films of La1-xBaxMnO3 grown on (00l)-oriented LaAlO3 substrate via spin-coating method

Herein, the crystal structure, valence, and electrical transport properties of La1-xBaxMnO3 films were examined by preparing La1-xBaxMnO3 films with varying Ba content (x = 0.22, 0.24, 0.26, 0.28) on LaAlO3 substrates using the sol-gel spin coating technique. The La1-xBaxMnO3 films prepared in the study exhibit topographically demorphed and non-dense characteristics in the microstructure, which is mainly caused by the Volmer-Weber growth mode of the films and the volatilization of organic matter during the sol-gel sintering process for films preparation. The increase of Ba doping leads to MnO6 deformation, decrease in grain boundary scattering, increase in Mn4+ ion content, and enhancement of both the double exchange mechanism and the Jahn-Teller effect. The four-probe results showed that the peak resistivity of the films decreased significantly with the increase in Ba2+ doping, and the metal-insulator transition temperature (Tp) shifted to higher temperatures. Peak temperature coefficient of resistivity (TCR) corresponding temperature (Tk) increased from 283.05 K (x = 0.22) to 309.31 K (x = 0.28), which was consistent with the trend of Tp; the peak value of TCR decreased with the increase of Ba doping. When x = 0.24, the Tk of the La1-xBaxMnO3 films reach room temperature (294.25 K) with TCR = 9.01 % K−1. In conclusion, the electrical properties of La1-xBaxMnO3 can be optimized by varying the amount of Ba doping to obtain La1-xBaxMnO3 films with room-temperature Tk and higher TCR values, providing reasonable data support and theoretical explanation for the Ba doping mechanism.

Synthesis, curing kinetics and processability of a low melting point aliphatic silicon-containing bismaleimide

An aliphatic silicon-containing maleimide monomer 1,1'-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(1H-pyrrole-2,5-dione) (TBB) with low melting point (56 °C) was successfully synthesized based on maleic anhydride (MA) and 3,3'-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (BAT). The structure of TBB monomer was determined by FTIR, 1H NMR and 13C NMR. Meanwhile, the 3,3'-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (BAT) and 4,4’-Bismaleimidodiphenylmethane (BDM) monomers were respectively prepared from diallyl bisphenol A (DBA), following a 1:0.87 molar ratio, and named TD resins and BD resins. The curing kinetics, thermal stability and processability of TD resins and BD resins were discussed and compared. The activation energy (E) value of TD resins was 26.2% higher than BD resins, resulting in exothermic peak temperature (TP) of TD resins was higher than BD resins at different heating rates. Compared with BD resins, the crosslinking density (ve) of TD resins was reduced by 93.5%, which effectively destroyed the thermal stability of TD resins. However, TD resins exhibited outstanding processing window of 195.6 °C. The processing window of TD resins was 110.1% wider than that of the BD resins, indicating that the former had excellent processability. Overall, this study has enriched the discussion on the curing kinetics of aliphatic bismaleimide resins and has a positive influence on the design of resins monomer with low melting point.

Numerical study on heat transfer and flow characteristics of symmetric Tesla-type microchannel heat sinks

This study numerically investigates the thermal performance of multi-stage Tesla valve microchannels (TVM) and a symmetric variant (SYMTVM) using single-phase deionized water, with mass flow rates ranging from 0.5459 to 1.6377 g/s. Both designs, particularly under reverse flow, exhibit lower peak temperatures and reduced temperature gradients compared to forward flow. The SYMTVM, characterized by its increased vortices and bifurcations, periodically disrupts and redevelops the thermal boundary layer, enhancing heat transfer efficiency. The TVM exhibits a significantly higher pressure drop than the SYMTVM across all flow conditions, with the reverse flow in TVM reaching up to 2.48 times that of forward flow and exceeding SYMTVM, especially at a peak flow rate of 1.6377 g/s. The performance evaluation criteria (PEC) and thermal resistance criteria (PECTR) demonstrate the superior performance of SYMTVM, with a reduced connection angle between the trunk and helix regions enhancing thermal efficiency. Furthermore, the SYMTVM-Reverse structure with a 30° interconnection angle demonstrates superior performance compared to the conventional rectangular microchannel (RM), achieving a Nusselt number (Nu) that is five times higher than that of the RM and an overall performance up to 2.59 times greater. These results indicate the SYMTVM-Reverse’s high heat transfer efficiency and its capacity to effectively balance thermo-hydraulic performance, even with increased power dissipation.

Lignocellulose degradation and temperature adaptation mechanisms during composting of mushroom residue and wood chips at low temperature with inoculation of psychrotolerant microbial agent

Low ambient temperature become the limiting factor of composting in cold regions, thus hindering the recycle of agricultural and forestry wastes. In this study, the composting of mushroom residue and wood chips (MRWC) under low temperature was successfully implemented with inoculation of psychrotolerant cellulolytic microbial agent. Composting entered thermophilic stage on third day and the peak temperature reached to 66.25°C. After 84 days of composting, the degradation rate of cellulose and hemicellulose was 40.85% and 100%, respectively and the compost product was completely mature and met the requirements of organic fertilizer. Metagenomic and transcriptome sequencing were applied to reveal the microbial composition and their substrates conversion functions and adaptation mechanisms through low to high temperatures. Streptomyces, Mesorhizobium, Devosia, Aspergillus and Mucor were dominant genera in the microbial community that were rich in genes of lignocellulose degradation. Various genes related to low temperature adaptation (fatty acid, trehalose, mannitol, betaine metabolism and cold shock mechanism) and high temperature tolerance (heat shock and antioxidant) were detected during MRWC composting. These results indicated that microbes during composting constituted a high-efficiency lignocellulosic ultilization system in cold conditions. Besides, the microbes of microbial agent, especially Streptomyces and Aspergillus, possessed numerous genes involving in lignocellulose degradation and temperature adaptation and quite different temperature response patterns were found to perform in bacteria and fungi. The transcription levels of most these genes in Aspergillus exhibited significant differences under different substrates and temperature conditions, suggesting that the inoculum was crucial to the composting process and beneficial to maintain the temperature of piles. This study demonstrated that the application of psychrotolerant microbes was a promising strategy to increase the efficiency of composting in cold regions and these results could also provided the guidance for optimizing microbial agent.

The influence of pulse cell wall structure and cellular protein matrix on the in vitro digestion kinetics of starch: A dual encapsulation mechanism

The intrinsic characteristics and extrinsic processing of whole-pulse food modulate the starch digestion rate and extent. This study investigated the dual encapsulation mechanism of cell wall structure and protein matrix on the in vitro digestion properties of intracellular starch, using an isolated whole-pulse food model of intact pea cotyledon cells subjected to alkaline buffer and enzymatic treatments. Results showed that intact cells with the maximum protein matrix content (18.9 %) exhibited the lowest peak temperature (71.4 °C, uncooked and 58.1 °C, cooked), enthalpy change (3.4 J/g, uncooked and 2.0 J/g, cooked), relative crystallinity (11.6 %), and starch digestion rate (0.0248 min−1) and extent (11.9 %) compared to alkaline buffer and enzymatic treatments. Even after enzymatic treatment, cells with minimal protein matrix content (1.8 %) exhibited a starch digestion rate (0.0387 min−1) and extent (39.7 %), which were still lower than those of isolated starch (0.0480 min−1 and 56.8 %). These findings indicate that the protein matrix and cell walls act as a dual encapsulation system to slow starch hydrolysis. This provides a theoretical basis and technical guidance for developing low-glycemic whole-pulse foods.

Effects of temperature and stress evolution on microstructural change and mechanical properties during friction element welding

Dissimilar material joining is essential for improving the strength-to-weight ratio of materials for various applications. Friction element welding (FEW) is a promising solution for joining highly dissimilar materials that vary in strength and thickness. However, the influence of the process parameters on the material’s resultant microstructure and mechanical properties remains unclear. In this study, the relationship between microstructure and microhardness distribution of the welded specimen is experimentally studied, and the effects of temperature and stress evolution are revealed by a thermal–mechanical finite element model. It is found that the microhardness can be improved by over 50% in the central region due to microstructural change and grain refinement. The beneficial microstructural change can be achieved by inducing either a high peak temperature (over the austenitization temperature) or a high peak stress (over the hardening factor) during the FEW process, which can be obtained by controlling the endload and rotational speed of the friction element. The size of the region with improved hardness is observed to vary with the depth of deformation in the steel layer. For the transverse shear strength (TSS), it is observed that irrespective of the temperature levels reached, TSS increases with increasing stress in the steel layer. Temperature plays a crucial role when the steel layer’s temperature is higher than the austenitization start temperature wherein TSS increases with the temperature.

Experimental Investigation of Two-Pass Solar Dryer with V-Corrugated Absorber for Potato Slice Drying

Reducing the moisture level of food items can help prevent bacterial development and deterioration, extend shelf life, reduce packaging, and improve storage for convenient transportation. In this paper, a two-pass solar dryer with V-Corrugated absorber plate is developed. Its experimental performance evaluation in forced convection is carried out for potato chip drying. Various parameters like Hourly Variation of Solar Radiation Intensity, Temperature Distribution Curves inside Solar Dryer, Collector Efficiency Curve, Hourly Mass Loss of Potato Slices and Moisture Removal Comparison with Conventional Open Sun Drying Method are calculated and presented graphically. The peak temperature of the absorber plate reached 69.30C, and the air temperature at the collector outlet recorded the highest value at 57.50C. The average temperature difference of 28.580C is obtained for heat transfer by convection between the modified corrugated absorber plate and the air. An important finding in this experimental investigation was that there is an average 6.50C difference in temperature between the hot air exiting the collector and the air available at the bottom of the lower tray of the drying chamber, which should be reduced by applying means of avoiding heat loss. The highest collector efficiency is calculated as 88.9 % at 2 PM. The lowest efficiency is calculated at 9 AM as 66.8 %. The thermal inertia of the system adds to the collector efficiency in the last 2 hours of the experimentation and hence collector performs better than in the morning hours, though the insolation is nearly the same for the first and last two hours of sunshine. The percentage reduction in drying time was found to be 38.9 % for 50 % moisture removal from potato slices as compared to open sun drying.

An experimental and numerical investigation of the thermal performance of phase change materials in different triple-glazed window configurations

Phase Change Materials (PCM) may be excellent thermal insulation due to their poor conductivity and high heat capacity. Researchers are adding PCM to windows. This integration modifies internal surface temperatures and delays peak temperatures to improve indoor thermal comfort. This work investigates experimentally and numerically the impact of the different filling materials in four Triple Glazed Windows (TGW) configurations in an Iraqi environment: the first window filled two cavities with air (standard); the second window has one cavity filled with a PCM and the other with air; the third window has blinders with various tilt angles in one cavity and PCM in the other cavity; and in the fourth window, both cavities are filled with PCM. Numerically utilizing Computational Fluid Dynamics to evaluate the thermal performance of TGW. In August, when the solar radiation was at its maximum (623 W/m2), the results showed that the peak interior surface temperature dropped by 4.51, 13.28 and 11.53 % in the TGW configurations (PCM-air), (blinder-PCM), and (PCM-PCM), compared to the standard TGW. The fourth window increased the time lag by 2 h, effectively shifting the load and in the third window, the best tilt angle blinder is 45°

Thermal performance investigation of microencapsulated phase change material enhanced with graphene nanoplatelets in double-glazing applications

Effective heat energy storage is crucial for thermal energy management. The utilization of latent heat storage methods is widely prevalent across various engineering applications for enhancing energy efficiency. In this study, the energy storage performances of Phase Change Materials (PCMs) achieved by incorporating graphene nanoplatelets into a microencapsulated PCM were experimentally analyzed for double-glazing applications. Changes in thermal energy storage and heat transfer performance by incorporating graphene nanoplatelets into the PCM at two different mass ratios (1 % and 0.1 %) were investigated. The results obtained from light intensity and temperature measurements, as well as thermal camera imaging, were evaluated together. The results support the contribution of graphene nanoplatelets addition to microencapsulated PCMs in enhancing thermal performance during both heating and cooling periods. Among the investigated cases, the highest mass ratio of 1 % graphene nanoplatelets addition led to a major 10 °C increase in peak temperature compared to the reference condition. In contrast, this increase in peak temperature was accompanied by a mere 14 % decrease in average light levels. This research underlines the potential of graphene-enhanced microencapsulated PCMs in optimizing thermal management systems for double-glazing applications, offering a promising pathway towards enhancing energy efficiency and thermal comfort in building environments.

Study on the Influence of Laser Power on the Heat–Flow Multi-Field Coupling of Laser Cladding Incoloy 926 on Stainless Steel Surface

In order to explore the influence of laser power on the evolution of molten pool and convective heat transfer of laser cladding Incoloy 926 on stainless steel surface, a three-dimensional thermal fluid multi-field coupled laser cladding numerical model was established in this paper. The variation of latent heat during solid-liquid phase transformation was treated by apparent heat capacity method. The change in the gas–liquid interface was tracked using the mesh growth method in real time. The instantaneous evolution of temperature field and velocity flow field of laser cladding Incoloy 926 on a stainless steel surface under different laser power was discussed. The solidification characteristic parameters of the cladding layer were calculated based on the temperature-time variation curves at different nodes. The mechanism of the impact of laser power on the microstructure of the cladding layer was revealed. The experiment of laser cladding Incoloy 926 on 316L surface was carried out under different laser power. Combined with the numerical simulation results, the effects of laser power on the geometrical morphology, microstructure and element distribution of the cladding layer were compared and analyzed. The results show that with the increase in laser power, the peak temperature and flow velocity of the molten pool surface both increase significantly. The thermal influence of the molten pool center on the edge is enhanced. The temperature gradient, solidification rate, and cooling rate increased gradually. The microstructure parameters (G/R) are relatively small when the laser power is 1000 W. In the experimental range, the dilution rate and wetting angle of the cladding layer both increase with the increase in laser power. When the laser power is 1000 W, the alloying elements of the cladding layer are more evenly distributed and the microstructure is finer. The experimental results are in good agreement with the simulation results.