Arrhenius Equation Research Articles

Effect mechanism of Nb addition on grain refinement and inhibition of discontinuous precipitation of Cu–15Ni–8Sn alloy

Cu–15Ni–8Sn-xNb alloys (x = 0, 0.2, 0.6 wt%) were prepared using a medium-frequency induction melting furnace. The effect of Nb addition on grain refinement and inhibition of discontinuous precipitation (DP) in Cu–15Ni–8Sn alloys was systematically studied to elucidate the mechanism by which microstructural characteristics contribute to strength improvement. The results indicate that the increase the Nb content from 0 to 0.6 wt% reduces the average grain size of the as-cast alloy from approximately 524.8 μm to approximately 81.3 μm, and significantly decreases the lamellar transition structure region (α+γ). During solution treatment, dispersed needle-like NbNi3 phases were observed in the Cu–15Ni–8Sn-0.2Nb alloy. After aging, the DP growth rate in the Cu–15Ni–8Sn-0.2Nb alloy was notably slower than those of the other alloys. This was attributed to NbNi3 phases at the grain boundaries hindering DP nucleation, with intragranular NbNi3 phases inhibiting DP growth. The phase transformation order of the solid solution Cu–15Ni–8Sn-0.2Nb at 673 K aging is: spinodal structure → D022 ordered phase → L12 ordered phase → DP. The hardness and tensile strength of the Cu–15Ni–8Sn-0.2Nb alloy peaked at 338.3 HV and 725.42 MPa, respectively, after aging for 120 min. Using the Johnson–Mehl–Avrami–Kolmogorov (JMAK) and Arrhenius equations, the activation energies of DP in Cu–15Ni–8Sn-xNb (x = 0, 0.2, 0.6 wt%) alloys were calculated to be 93.19, 148.64, and 98.33 kJ/mol, respectively. These values suggest that the diffusion of DP atoms in the Nb-containing alloys is hindered, which effectively inhibits DP formation.

Lifetime prediction of EPDM sealing materials with thermal aging under constant compression

Abstract EPDM (Ethylene Propylene Diene Monomer) is an important engineering sealing material. Thermal aging leads to a decline in its service life. In this study, the static sealing lifetime of EPDM sealing materials is investigated by thermal aging experiments under constant compression. Based on the variation pattern of compression set over aging time at different aging temperatures (80 °C, 100 °C, and 120 °C), a lifetime prediction model for EPDM sealing materials is derived using chemical reaction kinetics and the Arrhenius equation. The model is compared with the experimental results. The results show that the prediction model is highly reliable. The theoretical life of EPDM after thermal aging at 25 °C is 30.6 years, 53.1 years, and 89.1 years, respectively, when the compression set is 40%, 45%, and 50 %.

Evaluation method of accelerated aging life of internal pressure seal layer of flexible composite hose

Abstract Aiming at the lack of evaluation methods for the life prediction of the inner pressure seal layer of in-service flexible composite hoses, the accelerated aging test method, which is the same as the transport medium and environmental conditions, and the Arrhenius equation principle are adopted to fit the life curve at different temperatures, so as to solve the problem that the life prediction of in-service flexible composite hoses is not possible at present. It provides the basis for the integrity management of flexible composite hose. The results show that the established aging life prediction model can meet the actual application requirements. The crosslinked polyethylene (XLPE) of internal pressure seal can be used for 76 years.

Kinetic analysis of dehydration/dehydroxylation from carbonaceous chondrites by in situ heating experiments under an infrared microscope

AbstractCI, CM, and CR carbonaceous chondrites contain hydrous minerals, indicating that their parent bodies underwent aqueous alteration at low temperatures. Some of these chondrites, such as heated CM, CI, and CY chondrites, experienced thermal dehydration by impacts or solar radiation after aqueous alteration. This study conducted heating experiments on carbonaceous chondrites and evaluated their dehydration/dehydroxylation kinetics in an effort to explain the thermal history of the parent asteroids of heated carbonaceous chondrites using their degrees of dehydration/dehydroxylation of hydrous minerals. Murchison (CM2.5) and Ivuna (CI1), relatively primitive (having not undergone thermal alteration) carbonaceous chondrites, were used as starting materials. Weakening in the OH band at ~3680 cm−1 (2.72 μm) with isothermal heating at 350–500°C (Murchison) and 450–525°C (Ivuna) were observed under in situ infrared spectroscopy (FT‐IR) equipped with a heating stage. To determine the rate constants, the decrease in the OH band was fitted using kinetic models such as first‐order reactions, two‐dimensional diffusion, and three‐dimensional diffusion. The apparent activation energies and frequency factors were determined using the Arrhenius equation. Time–temperature transformation diagrams were drawn to represent the decrease in the OH‐band intensity as a function of temperature and heating duration. Such kinetic approaches can provide constraints on the temperature and time of the dehydration/dehydroxylation processes and enable us to estimate long‐term effects from experiments in the laboratory within a short time.

Long-term memory induced correction to Arrhenius law

The Kramers escape problem is a paradigmatic model for the kinetics of rare events, which are usually characterized by Arrhenius law. So far, analytical approaches have failed to capture the kinetics of rare events in the important case of non-Markovian processes with long-term memory, as occurs in the context of reactions involving proteins, long polymers, or strongly viscoelastic fluids. Here, based on a minimal model of non-Markovian Gaussian process with long-term memory, we determine quantitatively the mean FPT to a rare configuration and provide its asymptotics in the limit of a large energy barrier E. Our analysis unveils a correction to Arrhenius law, induced by long-term memory, which we determine analytically. This correction, which we show can be quantitatively significant, takes the form of a second effective energy barrier E′<E\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E^{\\prime} \\, < \\, E$$\\end{document} and captures the dependence of rare event kinetics on initial conditions, which is a hallmark of long-term memory. Altogether, our results quantify the impact of long-term memory on rare event kinetics, beyond Arrhenius law.

A hybrid battery degradation model combining arrhenius equation and neural network for capacity prediction under time-varying operating conditions

Capacity degradation modeling and remaining useful life (RUL) prediction play a pivotal role in enhancing the safety of battery energy storage systems. Lithium-ion batteries utilized in the systems are subjected to intricate and variable operating conditions, including temperature, charging/discharging rates and depth, which result in time-varying degradation rates. However, most existing models for battery capacity prediction have the limitation of ignoring the quantitative effects of time-varying operating conditions on degradation. Therefore, a hybrid battery capacity degradation model combining Arrhenius equation and lightweight Transformer is constructed. The effects of operating conditions on capacity degradation rates are introduced by an improved Arrhenius degradation equation. The coordinate ascent method embedded with Newton descent is used for estimating the model parameters. Then, the unknown mapping relationships between the degradation statistical features extracted from monitoring data and the degradation factors are captured by the light-weight Transformer. Finally, a novel framework consisting of future capacity and RUL predicting is constructed based on sequential importance resampling (SIR). For the purpose of verification, the cyclic charge-discharge experiments of eight battery cells under two distinct operating profiles are designed and conducted. Compared with other models, the proposed model achieves the best prognostics performance on the tested cells.

Microstructure and hydrogenation/dehydrogenation properties of ball-milled PrMg12/Ni alloy powders

Amorphous and nanocrystalline PrMg12 is ball-milled with 30 wt% Ni powder. The impact of ball milling time on the thermodynamics and kinetics of hydrogen storage in this alloy is systematically studied. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) were employed to characterize the phase composition and microstructure. The result shows that the microstructure of PrMg12+30 wt%Ni alloy is predominantly amorphous and nanocrystalline. Prior to hydrogen absorption, the primary phases were identified as PrMg12, Ni and Mg2Ni. Following hydrogenation, these phases transform into MgH2 and Mg2NiH4. Pressure-composition-temperature (PCT) curves and kinetic data were acquired using a Sieverts apparatus. The thermodynamic and kinetic parameters are calculated by combining Van't Hoff equation, JMAK model and Arrhenius equation. The effect of ball milling time on the enthalpy and entropy changes of hydrogen desorption was found to be negligible. Notably, the activation energy for dehydrogenation reached a minimum value of 79.86 kJ/mol after 10 h of ball milling.

Hot deformation behavior and microstructural evolution of a new type of 7xxx Al alloy

Optimizing the thermal deformation parameters of Al alloys is beneficial for achieving grain refinement, avoiding microscopic defects in materials, and significantly enhancing the mechanical properties of Al alloys. In this study, the hot deformation behavior of a new type of 7xxx Al alloy was investigated through hot compression tests at strain rates of 10−3-1 s−1 and temperatures of 250–420 °C. The constitutive equation was successfully established using the hyperbolic sine form of the Arrhenius equation, accurately describing the flow stress. The hot processing map was obtained by overlaying the power dissipation map and the instability map, determining the optimal hot working parameters to be in the range of 325–373 °C, 0.45–1 s−1. In the safe region, dynamic recovery (DRV) and dynamic recrystallization (DRX) were predominant. The instability in the low-temperature region was attributed to the grain boundary pinning effect caused by grain boundary precipitation, while the instability in the high-temperature region was associated with local shear bands induced by uneven plastic strain. The hot processing map establishes a good connection with the microstructural evolution of the new type of 7xxx Al alloy under different hot deformation parameters.

Influence of temperature and dry density coupled effects on HTO, 36Cl, 85Sr and 133Ba diffusion through compacted bentonite

This study investigated the combined impact of temperature (from 25 to 80 °C) and dry density of bentonite (from 1.2 to 1.65 g·cm−3) on the apparent diffusion coefficient, Da, of four radionuclides (HTO, 36Cl, 85Sr and 133Ba) in a Ca-Mg bentonite. In this study, the different porewater chemistry, present under the specific experimental conditions -- a factor often overlooked in diffusion studies -- was explicitly considered. As a support to diffusion studies, batch sorption tests were carried out at different temperatures (25, 40, 60, and 80 °C) with the sorbing elements (85Sr and 133Ba).The planar source method was used for the determination of apparent diffusion coefficients, Da, which demonstrated its efficacy for both conservative (HTO and Cl) and sorbing elements. For all the investigated radionuclides, Da values decreased with increasing the clay dry density and increased with increasing temperature. Notably, the highest Da value (1·10−9 m2 s−1) was attained for HTO diffusion in the clay at 1.2 g cm−3 and 80 °C, while the lowest Da (3.6·10−12 m2 s−1) value was determined for Ba diffusion at 1.65 g cm−3 and 25 °C.The experimental Da values were analysed employing the Arrhenius law and the Stokes-Einstein equations. Results revealed that diffusion data are in a reasonable agreement with Arrhenius behaviour, but deviations from the Stokes-Einstein equation were observed for compaction densities higher than 1.4 g cm−3.

Experimental investigation of the multi-layer wetting behavior of electrode-separator-composites in lithium-ion batteries

The success of lithium-ion batteries and their application in electromobility is highly dependent on their scalable and cost-efficient manufacturing. Herein, electrolyte filling and wetting are time-consuming and quality-critical process steps, which have been, on the material level, primarily researched on an intra-material level for single-cell components while lacking overarching investigations for inter-material effects during wetting. This study demonstrates for the first time an experimental methodology designed to systematically quantify the interaction effects between different electrode-separator-composites during wetting by varying product components and process parameters. The investigation reveals a quantifiable interaction within a two- or three-layer material combination of anode, separator, and cathode, which can be discerned into distinct anode and cathode interaction effects, maintaining consistency across the product and parameter variations. Through the analysis of activation energy using the Arrhenius equation, the study observe a combinatorial relationship for modeling multi-layer wetting. Multi-layer wetting rates increase by 215 % compared to single material rates. Higher temperatures boost penetration rates due to lower viscosity, but reduce the interaction effect. These insights contribute to an application-orientated understanding of electrode-separator-composite wetting behavior and open up more possibilities for an optimized manufacturing process through expanding methodical exploration of strategies for counterbalancing poor wettability.

Diffusion of iron in zinc selenide during hot isostatic pressing

The diffusion of iron impurities in zinc selenide (ZnSe) during hot isostatic pressing (HIP) in the temperature range T = 1000–1300 °C and pressures P = 100–190 MPa has been investigated. The iron concentration and its distribution over the sample volume with a step from 20 to 50 μm was determined by IR spectroscopy in combination with an IR microscope. The diffusion coefficients of Fe in ZnSe at various temperatures and pressures were determined. The diffusion coefficients of Fe in ZnSe at P = 100 MPa and T = 1000 °C were (5.3 ± 0.6)x10−10 cm2/s, T = 1300 °C were (9.4 ± 0.9)x10−9 cm2/s. It is shown that the temperature dependences are described by the Arrhenius equation, and the isostatic pressure does not affect the value of the diffusion coefficients.

Microstructure, hydrogen storage properties, and thermodynamic characterization of ball-milled Mg90Ni5Y5 alloy

The hydrogen storage properties of the Mg90Ni5Y5 alloy were studied, which was prepared by vacuum electromagnetic induction melting and ball milling. The microstructure and phase evolution of the ball-milled alloys during the process of hydrogen absorption and desorption were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The alloys hydrogen storage properties were measured by semi-automatic Sievert instrument. Results show that the hydrogenated sample was composed of MgH2, Mg2NiH4 and YH3 phases. After dehydrogenation, Mg2NiH4 and MgH2 phases were completely decomposed, and YH3 could only be decomposed into YH2. After 2 cycles of adsorption dehydrogenation, the alloy was completely activated, and the maximum hydrogen desorption capacity was about 5.1 wt %. According to the Arrhenius equation, the ball-milled alloy activation energy of the dehydrogenation reaction of is only 75.7 kJ/mol.

A shelf life prediction model of Actinidia arguta ‘Chang Jiang No.1’ based on postharvest quality evaluation combined with fuzzy mathematics

Actinidia arguta has good taste and nutritional value. It is a climacteric fruit that is not durable during storage and has a short shelf life. To investigate the effects of storage and transportation on the quality of the early maturing variety Chang Jiang No. 1 (CJ No. 1), shelf life models were developed applicable at different temperatures. Fuzzy mathematics was used to evaluate the sensory senses of different storage stages at 2, 5, 15 and 25 °C, and the storage end-time was determined to be 35, 25, 15 and 10 days, respectively. All indices followed zero-order reaction kinetics (ΣR02 > ΣR12) and kinetic parameters k, A and Ea were calculated. Combined with the Arrhenius equation, a kinetic model was established based on key indices. The mean relative errors (MRE) of the key indices and shelf-lifeAll (SLAll) were less than 10% when comparing predicted and measured values. The weight of each index was determined using the Analytic Hierarchy Process (AHP), and a consistency test was conducted. Samples at 20 °C were selected to verify the model. The shelf life of CJ No.1 from 2 to 25 °C can be predicted according to the weighted model. The results of this study can help distributors and consumers determine the best time to eat A. arguta and the appropriate storage time. The ideas and methods of this study can also be promoted and applied to other fruit and vegetables to achieve a wider temperature range and a method of prediction of their shelf lives.

Flow Activation Energy of High-Concentration Monoclonal Antibody Solutions and Protein-Protein Interactions Influenced by NaCl and Sucrose.

The solution viscosity and protein-protein interactions (PPIs) as a function of temperature (4-40 °C) were measured at a series of protein concentrations for a monoclonal antibody (mAb) with different formulation conditions, which include NaCl and sucrose. The flow activation energy (Eη) was extracted from the temperature dependence of solution viscosity using the Arrhenius equation. PPIs were quantified via the protein diffusion interaction parameter (kD) measured by dynamic light scattering, together with the osmotic second virial coefficient and the structure factor obtained through small-angle X-ray scattering. Both viscosity and PPIs were found to vary with the formulation conditions. Adding NaCl introduces an attractive interaction but leads to a significant reduction in the viscosity. However, adding sucrose enhances an overall repulsive effect and leads to a slight decrease in viscosity. Thus, the averaged (attractive or repulsive) PPI information is not a good indicator of viscosity at high protein concentrations for the mAb studied here. Instead, a correlation based on the temperature dependence of viscosity (i.e., Eη) and the temperature sensitivity in PPIs was observed for this specific mAb. When kD is more sensitive to the temperature variation, it corresponds to a larger value of Eη and thus a higher viscosity in concentrated protein solutions. When kD is less sensitive to temperature change, it corresponds to a smaller value of Eη and thus a lower viscosity at high protein concentrations. Rather than the absolute value of PPIs at a given temperature, our results show that the temperature sensitivity of PPIs may be a more useful metric for predicting issues with high viscosity of concentrated solutions. In addition, we also demonstrate that caution is required in choosing a proper protein concentration range to extract kD. In some excipient conditions studied here, the appropriate protein concentration range needs to be less than 4 mg/mL, remarkably lower than the typical concentration range used in the literature.

Misidentified subglacial lake beneath the Devon Ice Cap, Canadian Arctic: a new interpretation from seismic and electromagnetic data

Abstract. In 2018 the first subglacial lake in the Canadian Arctic was proposed to exist beneath the Devon Ice Cap, based on the analysis of airborne radar data. Here, we report a new interpretation of the subglacial material beneath the Devon Ice Cap, supported by data acquired from multiple surface-based geophysical methods in 2022. The geophysical data recorded included 9 km of active-source seismic-reflection profiles, seven transient electromagnetic (TEM) soundings, and 17 magnetotellurics (MT) stations. These surface-based geophysical datasets were collected above the inferred locations of the subglacial lakes and show no evidence for the presence of subglacial water. The acoustic impedance of the subglacial material, estimated from the seismic data, is 9.49 ± 1.92 × 106 kg m−2 s−1, comparable to consolidated or frozen sediment. The resistivity models obtained by inversion of both the TEM and MT measurements show the presence of highly resistive rock layers (1000–100 000 Ω m) directly beneath the ice. Re-evaluation of the airborne reflectivity data shows that the radar attenuation rates were likely overestimated, leading to an overestimation of the basal reflectivity in the original radar studies. Here, we derive new radar attenuation rates using the temperature- and chemistry-dependent Arrhenius equation, and when applied to correct the returned bed power, the bed power does not meet the basal reflectivity threshold expected over subglacial water. Thus, the radar interpretation is now consistent with the seismic and electromagnetic observations of dry or frozen, non-conductive basal material.

Vertical channel‐structured cyanoethylated bacterial cellulose/polyethylene oxide composite solid electrolyte for all‐solid‐state lithium batteries

AbstractSolid polymer electrolytes (SPEs) have gained remarkable development within the realm of new energy resources. With its improved electrochemical stability and environmental‐friendly sustainability, bacterial cellulose (BC) has emerged as a promising candidate for applications in SPEs. Herein, bacterial cellulose was chemically cyanoethylated and integrated with lithium bis(trifluoromethanesulphonyl)imide/polyethylene oxide (PEO) based SPE. Some vertical channels are formed when trace amounts (0.5 wt%) of cyanoethylated bacterial cellulose (BC‐CN) are added to PEO‐based SPE, as revealed by SEM. This formula's corresponding PEO‐based SPE presents the highest ion conductivity of 5.7 × 10−4 S cm−1 at 60°C. The ion migration activation (Ea) deduced from the Arrhenius equation is 0.48 eV, lower than the value of 0.82 eV for the pristine PEO SPE. Besides, the Li+ migration number of this modified PEO‐based solid electrolyte is calculated to be a relatively high value of 0.33, while that of its counterpart, the pristine PEO SPE, is as low as 0.06. The all‐solid‐state lithium battery with PEO/0.5%BC‐CN SPE can operate stably for 115 cycles, which is longer than the 80 cycles achieved with the pristine PEO SPE. This study introduces a novel strategy for creating modified BC composites PEO‐based SPE.Highlights Bacterial cellulose was chemically cyanoethylated. Cyanoethylated bacterial cellulose composite polyethylene oxide (PEO)‐based solid polymer electrolytes (SPEs) are prepared in DMF. Opening pores penetrate the surface of the PEO/0.5% cyanoethylated bacterial cellulose (BC‐CN) SPE membrane. PEO/0.5% BC‐CN shows ionic conductivity of 5.7 × 10−4 S cm−1 at 60°C. Full cell with PEO/0.5% BC‐CN performs stably for 115 cycles.

Influence of temperature and heating duration on the thermal stability and flow characteristics of oil extracted from undersized crawfish (Procambarus clarkii) using non‐solvent method

AbstractUndersized crawfish (UC) have less economic value for sale in live or processed tail meat markets. Therefore, this study's objectives were to extract crawfish oil (CO) from UC and determine the impact of temperature and heating duration on CO's thermal stability and flow properties. However, extracting oil from these undersized specimens could potentially add value to the crawfish industry. Crawfish minced meat (CMM) was obtained by passing cooked and chilled UC through a pilot scale deboning machine. CO was extracted by agitating CMM at 70°C for 30 min, followed by centrifugation at 10,000×g. CO was analyzed for inherent physicochemical characteristics, heating time (0–8 h), temperature (45–85°C) effects on peroxide value (PV) and astaxanthin (ASX) content, and flow properties at 5–35°C. ASX content, PV, water activity, bulk density, specific gravity, and free fatty acid values in CO were found to be 1.52 ± 0.06 mg/g oil, 0.22 ± 0.07 meq/kg, 0.56 ± 0.02, 0.88 ± 0.00, 0.90 ± 0.00 g/mL, and 0.11 ± 0.04%, respectively. ASX content in CO showed no significant change within or between same‐temperature and different‐temperature heated samples after 8 h. PV increased significantly from 0 to 8 h of heating at all tested temperatures (45, 65, and 85°C; Δ = 0.31, 0.51, and 10.76 meq/kg, respectively). CO had pseudoplastic characteristics below 30°C and Newtonian flow from 30 to 35°C. The Arrhenius equation suitably described the relationship between temperature and apparent viscosity of CO. This study characterized a seldom‐researched oil (CO containing ASX) and provided insight into its ability to resist thermal degradation.

Cyclohexane dehydrogenation: Critical evaluation of parameter estimation procedures for kinetic modeling

In the present paper a comparison between different parameter estimation procedures commonly used for the kinetic modeling of chemical reaction is performed, based on experimental measurements of the cyclohexane dehydrogenation to benzene. The obtained results show that, when the Arrhenius equation parameters are estimated from estimates of the rate constant taken at different temperatures, larger parameter uncertainties and correlations are obtained, particularly when the variances of the experimental measurements are not considered during the estimation process. It is also observed that an apparent kinetic compensation effect occurs when the experimental data are separated according to the inlet partial pressure and catalyst mass in the reactor, mainly due to the existing and unavoidable experimental uncertainties and parameter correlations. Additionally, it is shown that larger uncertainties and correlations are obtained when the parameter estimates are computed through the differential method, which can also lead to poorer model predictions of the experimental data. Finally, it is shown that the simultaneous one-step estimation of all model parameters through the integral method and considering the available experimental uncertainties can provide the most accurate parameter estimates, making use of mathematical expressions that describe how variances of the experimental measurements depend on the experimental conditions.

Hydrogen diffusion and hydrogen embrittlement in iron (steel)

This article examines the diffusion of hydrogen (H-diffusion) and the temperature dependences of the diffusion coefficient of hydrogen (DH) in the metal (M)-hydrogen system. The metal used was iron and low-alloy steel. Taking into account experimental data on hydrogen diffusion in the Fe-H and steel-H systems, the main diffusion parameters were calculated and compared. It is shown that the temperature dependences of the hydrogen diffusion coefficient in metal samples in a one-stage reaction under isothermal conditions are described by the Arrhenius equation. For some M-H systems, experimental data show a deviation of the diffusion coefficient from the ideal one calculated using the Arrhenius equation. This discrepancy can be eliminated using the statistical theory of absolute reaction rates. For the temperature range 25–1250 oС, the pre-exponential coefficient and activation energy of hydrogen diffusion in a body-centered cubic (bcc) lattice of iron (α–Fe) were calculated using the Arrhenius equation. These parameters make it possible to describe the dependence of the rate of hydrogen diffusion in a metal on temperature and to predict the behavior of hydrogen diffusion when changing the conditions of the kinetic process (concentration of substances, pressure, structure, composition, etc.). Tabular values of the calculated pre-exponential factor and activation energy of hydrogen diffusion in previously studied iron-based samples are presented. The temperature dependences of the hydrogen diffusion coefficient in a lattice of iron α–Fe can be divided into low-temperature and high-temperature regions. The calculated diffusion parameters of hydrogen in the metal lattice for the low-temperature 25– 800 oC and high-temperature 800–1250 oC regions differ markedly from each other. In addition, these calculated values are significantly influenced by the structure and composition of the metal. We also studied the diffusion of hydrogen in α-iron using ab initio density functional calculations. Molecular dynamics calculations using transition state theory were used. The calculated diffusion coefficient of hydrogen in α-Fe is consistent with previously obtained experimental data. Hydrogen embrittlement (HE) is considered using internal pressure, hydrogen enhanced localized plasticity (HELP) and hydrogen enhanced decohesion embrittlement (HEDE) theories.

Performance analysis of a novel air filtration and sterilization PV-Trombe wall

Bioaerosols have received widespread attention since the outbreak of Coronavirus Disease 2019 owing to their harmful effect on public health. To deal with indoor bioaerosols in an energy-saving method, an air filtration and sterilization PV-Trombe wall was proposed in this study. An experiment rig concerning thermal sterilization of aerosolized Klebsiella pneumoniae was set up to test its feasibility and effectiveness at different exposure temperature and residence time. With the experimental data, an inactivation model was derived based on the first kinetic model and Arrhenius equation. Besides, a mathematic model concerning heat and mass transfer was established for simulating the system performance at different conditions. The results reveal that: (1) The survival ratio of bioaerosols was 0.848, 0.689, 0.493 and 0.257 for the exposure temperature of 45 °C, 60 °C, 73 °C and 85 °C at the residence time of 6.5 s (2) the survival ratio predicted by the inactivation model corresponded well with the experimental results and the root mean square error was 0.041. (3) The electrical and thermal efficiencies were 0.134 and 0.218 while the indoor bacterial concentration was reduced by over 60 % with bacterial quantity of filter maintained at a low level. (4) The increase of air velocity could significantly improve the purification performance.