High Temperature Heat Research Articles

Fluorobenzene as new working fluid for high-temperature heat pumps and organic Rankine cycles: Energy analysis and thermal stability test

Industrial high-temperature heat pumps and Organic Rankine Cycles play a pivotal role in reducing CO2 emissions of the industrial sector. While several eco-friendly refrigerants have been explored for subcritical heat pumps below 150 °C, above this threshold only a few fluids can be adopted.In this article, fluorobenzene (C6H5F) is proposed for the first time as a versatile working fluid suitable for both HTHP and ORC systems. Notably, it possesses a near-zero Global Warming Potential, null Ozone Depletion Potential, low cost, and low toxicity. The thermo-chemical stability of fluorobenzene is experimentally investigated with an advanced procedure, simulating the presence of the non-condensable-gases removal system in real plant operating conditions. The yearly rate of unimolecular decomposition is estimated less than 4 % at 350 °C, and even after 400 h of thermal stress no decomposition products have been detected in the liquid phase through Fourier Transform Infrared Spectroscopy.In a direct heat exchange case study, coupled with exhaust gases at 390 °C, fluorobenzene achieves a net power production higher than other commercial fluids adopted in high-temperature units. In subcritical two-stage throttling heat pump condensing at 180 °C fluorobenzene shows a good Coefficient of Performance of 3.25 at 100 °C temperature lift.

Investigation on the microstructure, mechanical properties and chlorine resistance of fine aluminum alloy wires

Wire bonding is a fundamental and mature technology in semiconductor packaging process, primarily using materials such as gold, silver, aluminum, and copper for the wires. To address application limitations of aluminum wires, such as low electromigration resistance and limited ductility, techniques including to enhance alloying (with Zn and Si), heat treatment, and surface treatment are employed to enhance the performance of aluminum alloy wires and broaden their application value. This study selects Al-3Zn-0.3Si (AZS303) and Al-7Zn-0.3Si (AZS703), with AZS303 undergoing gold plating to produce AC-AZS303 wires. Various high-temperature heat treatments are applied, verifying that under 400 °C conditions, the AZS series aluminum alloy wires exhibit grain growth and form single-crystal equiaxed grain structures, resulting in stable mechanical properties and excellent electrical performance. Additionally, the AC-AZS303 wires optimize resistance values through gold layer diffusion induced by the electrothermal effect.Chlorine experiments indicates that the gold plating on AC-AZS303 can't enhance the aluminum wire's resistance to chlorine corrosion. However, the alloying effect of zine and silicon elements imparts excellent chlorine corrosion resistance to the Al-Zn-Si wires. This study of bonding properties examines the bond strength and observes the bonded area of Al-Zn-Si wires after bonding. It is noted that the H400-AZS303 wire exhibits the best bond strength and bonding area, demonstrating good bonding with the substrate.

Research on the microstructure and mechanical properties of functional gradient materials of TC4/TC11 titanium alloys for wire arc additive manufacturing with different transitional forms

Functional gradient materials (FGMs) have garnered increasing interest for their potential in material and structural design. Additive manufacturing, as a kind of free manufacturing and near-net shaping technology with in-situ controllability of materials, is the dominant technology for fabricating FGMs. While numerous studies have been conducted on titanium alloy FGMs, there is still a lack of research on the structure and properties of the material with the number of transitional layers. This study employs double-wire arc additive manufacturing to fabricate FGMs composed of TC4 and TC11 alloys. The study examines the utilization of direct and continuous transition forms in conjunction with stress relieving and solution aging heat treatment processes. The composition, grain morphology, microstructure, and mechanical properties of FGMs are analyzed. Results indicate that in samples employing direct transition, higher heat treatment temperatures and durations lead to a more uniform composition and microstructure. Additionally, the interface morphology becomes increasingly indistinct, and transversal elongation at the interface is enhanced by the strain compensation of the two materials. In continuous transitional samples, an increase in the number of transitional layers results in a more uniform microstructure near the interface, leading to a reduction in interface morphology and an enhancement of mechanical properties. The fracture position tends to shift closer to the TC4 side, with both process forms exhibiting ductile fractures. The plasticity of the TC4 part is superior, and the ductile fracture morphology is more pronounced. This study offers a valuable experimental foundation for investigating the direct and continuous transition of titanium alloy FGMs.

Exergy analysis of hybrid air-conditioning systems with different evaporative-cooling condensers under hot-humid climates

Evaporative cooling (EC) technology can effectively improve the energy efficiency of the mechanical vapor compression (MVC) system by enhancing the heat exchange capacity of its condenser. However, the current evaporative-cooling condenser system is usually only equipped with a single-stage evaporative cooler as the precooling unit, and these designs are mainly suitable for hot-dry conditions. In this study, three hybrid air-conditioning systems with different two-stage evaporative-cooling condenser configurations were proposed, one is single-condenser type and the other two are dual-condenser type, which are used to improve the exergy performance and adaptability of the evaporative condenser system under hot-humid climates. Then, the all systems were modeled via the distributed parametric method and analyzed comparatively based on the exergy method. A suitable exergy reference temperature at air saturation was discussed. Finally, the effect of four key parameters (ambient temperature and relative humidity, outdoor airflow rate and room heat load) was studied. The results showed that under the high temperature, relative humidity or room heat load conditions, the hybrid systems have a low exergy efficiency ratio (EXR) and high exergy efficiency (ηx,OEC). Among them, the newly countercurrent dual-condenser configuration (MVC-TSEC(C)) exhibits the best exergy performance under most hot-humid conditions. Compared to the conventional MVC system, the EXR and ηx,OEC of MVC-TSEC(C) increased by at most 35.0 % and 78.2 %, respectively. Moreover, its components like compressor, condenser and expansion valve have the maximum reduction rates of exergy destruction of 43.5 %, 17.2 % and 55.3 %, respectively.

Heat Supply to Industrial Processes via Molten Salt Solar Concentrators

About one-third of world energy production is destined to the industrial sector, with process heat accounting for about 70% of this demand; almost half of this quota is required by endothermic processes operating at temperatures above 400 °C. Concentrated solar thermal technology, thanks to cost-effective high-temperature thermal energy storage solutions, can respond to the renewable thermal energy needs of the industrial sector, thus supporting the decarbonization of hard-to-abate processes. Particularly, parabolic trough technology using binary molten salts as heat transfer fluid and storage medium, operating up to 550 °C, could potentially supply a large part of the high-temperature process heat required by the industry. In this work, four industrial processes, representative of the Italian industrial context, that are well suited for integration with molten salt concentrators are presented and discussed, conceiving for each considered process a specific coupling solution with the solar plant, sizing the solar field and the thermal storage unit, and computing the cost of the process heat and its variation with the storage capacity. Considering cost data from the literature associated with the pre-COVID-19 era, an LCOH comprising the range 5–10 c€/kWhth was obtained for all the cases studied, while taking into account more updated cost data, the calculated LCOH varies from 7 to 13 c€/kWhth.

Economic and environmental considerations for the deployment of industrial very high temperature heat pumps in European markets

Very high temperature heat pumps (VHTHP) have begun to emerge on the market during the past decade, providing an alternative to fuel-fire boilers for generating industrial process heat up to 200 °C. Large temperature lifts are common for VHTHPs, resulting in a reduced coefficient of performance (COP) compared to traditional heat pumps. Thus, the economic feasibility of operating VHTHPs becomes more dependent on local price conditions, and the environmental impact is affected by increased electricity usage. Both the economics and the environmental impact of operating industrial VHTHPs in place of fossil fuel-fired boilers in Europe are studied in this article. Discounted payback periods are estimated for the varying price conditions in Europe, and life cycle assessment tools are used to quantify the environmental impact of operating VHTHPs. Finland, Sweden, and Denmark were found to be ideal countries for VHTHP deployment, as they showcase both favorable economic conditions as well as generally small environmental impacts in the endpoint categories Human health, Climate change, and Resource usage, if local grid electricity is used. The effect on the endpoint category Ecosystem impacts was generally larger for most countries, including the aforementioned three, mostly due to the use of biomass in the electricity grid.

An Innovative Azobenzene-Based Photothermal Fabric with Excellent Heat Release Performance for Wearable Thermal Management Device.

Azobenzene (azo)-based photothermal energy storage systems have garnered great interest for their potential in solar energy conversion and storage but suffer from limitations including rely on solvents and specific wavelengths for charging process, short storage lifetime, low heat release temperature during discharging, strong rigidity and poor wearability. To address these issues, an azo-based fabric composed of tetra-ortho-fluorinated photo-liquefiable azobenzene monomer and polyacrylonitrile fabric template is fabricated using electrospinning. This fabric excels in efficient photo-charging (green light) and discharging (blue light) under visible light range, solvent-free operation, long-term energy storage (706 days), and good capacity of releasing high-temperature heat (80-95 °C) at room temperature and cold environments. In addition, the fabric maintains high flexibility without evident loss of energy-storage performance upon 1500 bending cycles, 18-h washing or 6-h soaking. The generated heat from charged fabric is facilitated by the Z-to-E isomerization energy, phase transition latent heat, and the photothermal effect of 420nm light irradiation. Meanwhile, the temperature of heat release can be personalized for thermal management by adjusting the light intensity. It is applicable for room-temperature thermal therapy and can provide heat to the body in cold environments, that presenting a promising candidate for wearable personal thermal management.

N, S Co-Doped Carbon Nanotubes Loaded With Cu Nanoclusters For Efficient Oxygen Reduction Reaction.

Developing highly superior precious-metal-free electrocatalysts for oxygen reduction reaction (ORR) are challenging and great significance. In this study, it is reported that an efficient ORR catalysts with N and S co-doped carbon nanotubes anchored to copper (Cu) nanoclusters by mechanical grinding and high temperature heat treatment. The obtained Cu-S1-N-C electrocatalysts exhibited a high ORR performance with an onset potential (Eonest) of 0.989 V and a half-wave potential (E1/2) of 0.905 V (vs. RHE) in alkaline electrolyte, which was superior to that of commercial Pt/C catalyst. In contrast to N doping alone, the defect structures and active species of the catalysts were optimized by precise modulation of S-atom doping, and moreover, the introduction of S-atoms provided more thiophene-sulfur active sites. This study provides an innovative idea for designing excellent ORR catalysts.

Experimental Study on Startup Performance of a High-temperature Liquid Metal Heat Pipe with Fins

Experimental Study on Startup Performance of a High-temperature Liquid Metal Heat Pipe with Fins

Numerical method research and characteristics analysis on frozen start-up process of high-temperature heat pipe

Future space exploration technology requires a long-life and reliable power source that is not reliant on solar energy. Space micro-reactors are able to meet this need, with Heat Pipe Cooled Reactors (HPR) emerging as a notable type of space micro-reactor that has attracted widespread attention in recent years. The HPR utilizes high-temperature alkali metal heat pipes for heat transfer, which presents certain complexities due to the solid state of the alkali metals working medium at room temperature. This results in a three-phase transition during the high-temperature heat pipes start-up process, which significantly impacts the heat transfer characteristics and dynamic behavior of the HPR start-up process. Consequently, thorough research is necessary in this area. Numerical simulation is a crucial tool that can effectively analyze, predict, and guide experiments. This article utilizes the Finite Volume Method (FVM) to develop a simulation code for high-temperature heat pipe frozen start-up. Various physical models are integrated to describe different components of the heat pipe: the container is represented by a two-dimensional axisymmetric heat conduction equation, the wick region utilizes a Fixed Grid Method (FGM) to depict the melting process of the medium, and the vapor channel is described through a two-dimensional axisymmetric compressible laminar flow. The wick region and vapor channel are coupled through the evaporation and condensation of the medium. For the vapor channel, numerical methods such as SIMPLE and PISO are used for solving. Adaptive time step and OpenMP acceleration are employed in the code to enhance computational efficiency. Finally, by comparing the calculated results with experimental data, the feasibility and accuracy of the code are assessed, highlighting special phenomena during the start-up process. The findings confirm that the developed code accurately predicts parameter changes during start-up, and can serve as a heat pipe analysis module for multi-physics coupling analysis of HPR.

Experimental study on the thermal performance of a high-temperature finned latent heat storage system

The primary objective of this study is to develop and evaluate the performance of a latent heat storage (LHS) system. A tube-in-tube heat exchanger configuration was used to design the LHS system. Sodium nitrate and air were employed as the phase change material (PCM) and heat transfer fluid (HTF), respectively. To mitigate the low thermal conductivity of the PCM, six circular fins were integrated on the HTF tube surface and experiments were conducted in an in-house experimental facility. Temperature plots from the charging-discharging experiments revealed that the HTF flow direction governs the heat transfer along the axis of the system. The sensible heat gain by the PCM in the range of 270–330 °C, led to an additional ⁓0.4 MJ of heat storage beyond the storage capacity of 1 MJ. Furthermore, increasing the inlet temperature from 400 °C to 440 °C reduced the charging time by 39.6 %, while reducing the inlet temperature from 210 °C to 170 °C decreased the discharging time by 18.2 %. Despite improved heat transfer, higher inlet temperatures adversely affected the thermal uniformity whereas, the increase in inlet air velocity enhanced both the dynamics of heat transfer and the thermal uniformity within the storage system.

Hesperidin Helps Improve the Intestinal Structure, Maintain Barrier Function, and Reduce Inflammation in Yellow-Feathered Broilers Exposed to High Temperatures.

To investigate the possible protective effect of hesperidin on intestinal damage caused by high-temperature heat stress in yellow-feathered broilers, 960 broilers aged 21 days were randomly divided into four groups: HT, HT300, HT450, and HT600, with each group receiving different amounts of hesperidin supplementation (0, 300, 450, and 600 mg/kg). The dietary supplementation of hesperidin could mitigate the elevation of corticosterone (CORT) and adrenocorticotropic hormone (ATCH) levels in serum from yellow-feathered broilers induced by heat stress. The supplementation of 300 mg/kg and 450 mg/kg of hesperidin reduced crypt depth and increased the V/C ratio in the small intestine compared to the HT group. The dietary supplementation of hesperidin decreased endotoxin and D-lactic acid levels in the blood, and dietary supplementation of 300 mg/kg of hesperidin increased the expression of claudin-1 and ZO-1 mRNA in the jejunum compared with the HT group. Furthermore, the dietary supplementation of 300 mg/kg of hesperidin decreased serum IL-1β and IL-6 levels. In comparison, supplementation with 300 mg/kg and 450 mg/kg of hesperidin decreased serum TNF-α levels in yellow-feathered broilers compared to the HT group. Moreover, the dietary supplementation of hesperidin decreased NF-κB mRNA levels. Overall, these data suggest that dietary supplementation with hesperidin potentially improves intestinal injury caused by heat stress in yellow-feathered broilers.

Numerical simulation of thermal-flow-magnetic coupling dynamics during P-type monocrystalline silicon removal in electrical discharge machining

To investigate the mechanisms underlying material removal and crater formation on semiconductor silicon in electrical discharge machining (EDM), this study presents a comprehensive thermal-flow-magnetic coupling simulation model, taking into account the synergistic effects of temperature, fluid dynamics and electromagnetic fields. Utilizing the model, the removal dynamics of P-type monocrystalline silicon within a monopulse discharge interval were meticulously simulated. Subsequently, the crater formation mechanism, as well as variations in the temperature and velocity fields, were thoroughly examined. The simulation model’s validity is experimentally confirmed. Findings indicate that an augmentation in pulse duration and thermal energy input precipitates a progressive expansion of the heat-affected zone in silicon. Concurrently, the temperature field’s expanse and the melting-vaporization frontier extend accordingly. The material undergoes instantaneous vaporization upon exposure to the high-temperature heat source. The volumetric expansion of the vapor is substantial, engendering a thermal explosive force that has a significant impact on the molten material. Ejection of material is attributed to the interplay between thermal explosive forces and electromagnetic influences. Experimental observations show that the morphology and dimensions of the simulated crater closely match those of the experimental crater, affirming the model’s capability to elucidate the crater formation mechanism in EDM processes.

Study of the physical properties of the half-heusler XBrH with (X= sr, Ca and mg) compounds

Half-Heusler alloys are among the most promising thermoelectric materials for medium- and high-temperature waste heat recovery applications. This study investigates the physical properties of Half-Heusler compounds XBrH, with X = Sr, Ca, and Mg. We explored the structural, electronic, optical, and thermoelectric properties of these compounds using density functional theory (DFT) as implemented in the Wien2k package. The Generalized Gradient Approximation (GGA) as proposed by Perdew-Burke-Ernzerhof (PBE) and the modified Becke-Johnson (mBJ) functional were employed to calculate the exchange-correlation interactions. After doing structural optimization for a range of parameters, we discovered that the SrBrH compound is more stable than the CaBrH and MgBrH compounds. Our results show that the density of state calculations indicate semiconductor behavior for the XBrH with (X = Sr, Ca, and Mg) compounds. We also evaluated the real and imaginary parts of the dielectric tensor, the refractive index, the absorption coefficient, the electron energy loss, and the real and imaginary components of the optical conductivity, among other optical parameters. Additionally, we investigated the figure of merit (ZT), electronic and lattice thermal conductivity, Seebeck coefficient, and electrical conductivity. The MgBrH, CaBrH and SrBrH compounds showed p-type behavior, with positive values for the Seebeck coefficient and the greatest value of ≈180 μV/K, according to the thermoelectric data. At 1000 K, the ZT reach their highest values for CaBrH, SrBrH, and MgBrH, respectively, at 2.9, 2.8, and 0.9. The physical properties of the XBrH with (X = Sr, Ca, and Mg) compounds have been studied in detail.

Experimental study on thermal–hydraulic performance of a nature-inspired mini-channel heat exchanger manufactured by 3D printing

Zigzag-channel printed circuit heat exchangers (PCHEs) are widely used in nuclear energy, solar energy, and aerospace due to their good heat transfer performance. However, the high flow resistance of zigzag channels leads to large pumping power consumption and thus limits the overall performance. Although previous modified channels could reduce the flow resistance of PCHEs, they also bring a decrease in the heat transfer efficiency. Inspired by river islands, this study proposes a novel nature-inspired channel. The nature-inspired channel heat exchanger, along with a traditional zigzag-channel heat exchanger, were manufactured by 3D printing. The high-temperature air-air flow and heat transfer experiments show that the nature-inspired channel heat exchanger increases the average heat transfer rate by 1.5% and significantly reduces the pressure drop by 34.85%. The addition of airfoil fins at the corners effectively alleviates the flow resistance caused by flow separation, reattachment, and collision, leading to a higher Nusselt number and a lower Fanning friction factor. The Nusselt number of nature-inspired channel is 59% higher than that of the zigzag channel with a 15° inclined angle. This work demonstrates that the nature-inspired channel could significantly reduce the flow resistance while maintaining high heat transfer efficiency compared with the traditional zigzag channel.

Advantageous Effects of Phase Transition-Modulated Electric Polarization of Hollow CuSx for Enhanced Electromagnetic Wave Absorption.

Scrutinizing the electromagnetic wave absorption mechanism of sulfides remains a challenge due to the variability of the modulation of the crystal structure of the sulfides. To take advantage of this variability, nanosheet-assembled Cu9S5/CN composites with sulfur vacancies were prepared in this study by self-assembly synthesis and subsequent high-temperature heat treatment. Systematic studies show the phase transition-dependent induced decrease in the conductivity, the defect site-induced difference in the charge density, the weakened vacancy formation of defect polarization loss, and the influence of valence state on electric dipole polarization loss and interfacial polarization loss, making the optimization of the dielectric constant a significant positive effect on the improvement of impedance matching. This work provides a reliable example and theoretical guidance for the crystal structure design for the preparation of a new generation of efficient sulfide-based wave-absorbing materials.

Performance and Economic Analysis of Two Types of High-Temperature Heat Pump Based on New Refrigerants

This paper proposes, for the first time, the research concept of comparing energy and economy between transcritical cycle high-temperature heat pumps and subcritical cycle high-temperature heat pumps with new refrigerants. Experiments and simulations are conducted to compare the system performance and economy of two heat pumps, and the effects of different factors on the performance of two heat pumps are analyzed. The results show that R744/R1234yf (90/10) and R515-1 are the preferred refrigerants for transcritical cycle heat pumps and subcritical cycle heat pumps, respectively. The COP of the R744/R1234yf (90/10) transcritical heat pump is generally higher than that of the R515B-1 subcritical heat pump, and compared to the R515B-1 subcritical heat pump, the cost recovery period of the R744/R1234yf (90/10) transcritical heat pump is about 9–15 years. Therefore, it is recommended that users who use heat pumps for a long time choose transcritical cycle heat pumps. Meanwhile, with the change of evaporation temperature, the system COP of the R515B-1 subcritical heat pump and R744/R1234yf (90/10) transcritical heat pump increases by 61.11% and 65.91%, respectively. In addition, the optimal charge amount for the R515B-1 subcritical heat pump is 81.8% of that of the R744/R1234yf (90/10) transcritical heat pump.

Gradient coating increases the temperature resistance of ceramic fiber fabric

Ceramic fiber fabric embrittlement at 1200 °C, resulting in poor tensile strength. In order to improve the tensile strength of ceramic fiber fabric after high temperature heat treatment. In this study, gradient coating is sprayed on the surface of ceramic fiber fabric by adjusting the composition of two kinds of slurry. The structure and property of ceramic fiber fabric with different coating are thoroughly investigated. The pore size of Al2O3-SiC porous transition layer is less than 1 μm, which limits the infiltration of the high-emission coating into the ceramic fiber fabric. A weak bond is formed between the ceramic fiber fabric and the porous transition layer, which induces the crack deflection. The flexibility of ceramic fiber fabric after heat treatment is significantly improved. After being heated by butane flame at 1200 °C for 20 min, the tensile strength of fiber fabric with gradient coating is double that of raw ceramic fiber fabric. The silicone cross-links to form a network, which improves the bonding strength of the gradient coating. Due to the high emissivity and low thermal conductivity of the gradient coating, the temperature of the ceramic fiber fabric is below 900 °C when heated by the butane flame.

Comprehensive lipidomics and flavoromics analysis reveals the formation mechanism of the unique flavor in quail egg yolks during thermal treatment

After thermal treatment, quail eggs pruduce an attractive flavor that is favored by consumers. In this study, the key aroma volatiles and their lipid precursors during thermal treatment were investigated by the electronic nose, GC-MS, GC-O-MS and UPLC-Q-Exactive HF-X. The results exhibited that the raw and fresh flavor of raw egg yolks came from 1-Octen-3-ol, 2-Ethyl-1-hexanol, 1-Decene, and 1-Undecene. 2-Methyl-3-octanone, Toluene, and some aromatic compounds worked synergistically to contribute to the aroma profile of boiled eggs. (+)-2-Bornanone, Octanal, 2-Methyl-butanal, Nonanal, (.+Dihydro-3-hydroxy-4,4-dimethyl-2(3 H)-furanone, 6,7-Dihydro-2,5-dimethyl-5 H-cyclopentapyrazine, (E)-2-methyl-6-(1-propenyl)-pyrazine, 2-Ethyl-3,5-dimethyl-pyrazine, 3,5-Diethyl-2-methyl-pyrazine, 2,5-Dimethyl-pyrazine were the key flavor compounds in the fried egg and gave it the popcorn and roasted flavors. The statistical analysis of the lipid profile revealed that brief, high-temperature heating (100 or 200 °C for 10 min) in typical boiled and fried quail eggs had minor effects on the lipid nutritional value. PE-related lipids, particularly those containing 18-carbon fatty acids, contributed to the aroma formation of fried quail eggs.Graphical

Corrosion of 316 SS in chloride molten salt for thermal energy storage: Inhibitory effects of Al powder

Abstract MgCl2-KCl-NaCl is regarded as one of the most prospective high-temperature thermal energy storage mediums and heat transfer fluids (HTF) for 3rd generation concentrated solar power (CSP) systems. However, high corrosion to alloys limits its application. In this paper, corrosion tests were conducted on 316 SS, in MgCl2-KCl-NaCl at 800°C with different content (0 wt.%,1 wt.%, and 10 wt.%) of Al powder addition as a corrosion inhibitor. The impact of Al powder was assessed through electrochemical methods, specifically impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). Following corrosion tests, the morphologies and phase compositions of 316 SS were determined by using scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD). The addition of Al powder can significantly reduce the corrosion current density of 316 SS in MgCl2-KCl-NaCl at 800°C, which was 183.29 times higher than that with 10 wt.% without Al addition. Al and the degree increased with increasing content of Al. With the addition of 1 wt.% Al, the thickness of the diffusion layer is significantly reduced, which was 54.6 μm (100 h), 275.1 μm (200 h), 370.4 μm (300 h), and 500 μm (400 h), respectively. When the addition of Al reaches up to 10 wt.%, the inwards diffusion of Al caused the formation of Al enriched layer, which was identified as the FeAl phase, on the surface of 316 SS during the high-temperature corrosion processes. The thickness of the Al enriched layer was associated with the diffusion time of Al, and its depth was 40.4 μm (100 h), 45.3 μm (200 h), 103.5 μm (300 h), and 139.5 μm (400 h).