Air Conditions Research Articles

Corrosion fatigue crack propagation behaviour in different micro-regions of steel/aluminum laser-MIG hybrid fusion-brazed joints

Evaluating corrosion fatigue crack propagation (CFCP) behaviour in different micro-regions of steel/aluminium welded joints is crucial for ensuring the safety and reliability of these joints in service environments. However, the CFCP behaviour of steel/aluminum welded joints has rarely been studied. This study explores the CFCP behaviour of steel/aluminium laser-metal inert gas hybrid fusion-brazed joints in different micro-regions under a simulated corrosive environment (3.5wt.% NaCl solution) at room temperature. A self-made 5 KN electronic servo testing machine was used to apply a sinusoidal wave load (stress ratio R = 0.1, frequency = 0.5Hz) to single-edge notched tensile specimens. The notches were located at the weld, heat-affected zone (HAZ) and steel/aluminium interface (abbreviated as interface). The fatigue crack propagation rate (da/dN) of different micro-regions in steel/aluminium welded joints followed the order of interface > weld > HAZ under corrosive environment and air conditions. Compared with air, the corrosive environment triggered a markedly higher da/dN, irrespective of notch location at the weld, HAZ or interface. This accelerated da/dN resulted from the combined effects of anodic dissolution, chloride ions and galvanic corrosion. The electron backscatter diffraction results indicated that compared with the weld and HAZ specimens, the HAZ specimen exhibited lower da/dN, attributed to its small grains, higher proportion of high-angle grain boundaries and increased geometrically necessary dislocation density. Fatigue striations were clearly observed on the weld and HAZ fracture surfaces, while a brittle fracture pattern was observed on the corrosion fatigue fracture surface for the interface.

The effect of temperature and humidity of air on the concentration of particulate matter - PM2.5 and PM10

Particulate matters accepted as air quality markers are also indicators of the health risk of the population, especially children, because of their increased susceptibility to the quality of the air they breathe. Understanding the correlations between the concentration of particulate matter in the outdoor air and meteorological conditions will help to take steps to reduce pollution and reduce the risk of threats to health and life. For many years, scientists from all over the world have been looking for relationship between the impact of meteorological conditions on the concentration of particulate matter. Despite this, it is still not known whether the relationships will be similar in all locations. Furthermore, there is no agreement among scientists on the direction and strength of the correlation between temperature, humidity, and particulate matter concentrations. The article presents an attempt to link the impact of meteorological conditions on particulate matter concentrations depending on the classification of the area into air quality index in the particulate matter (AQIPM) category. Three locations with a specific air quality index were included: extremely poor, moderate & fair and good. The research was carried out at nine locations near educational facilities. Four measurement series were carried out for each location. Spearman's correlation coefficient was used to assess the relationship with an assumed significance level of 0.05. A research hypothesis was adopted: The correlation between particulate matter and meteorological conditions is different in locations with different AQIPM. The results obtained clearly show that the relationships between meteorological conditions and the concentration of particulate matter depend on the classification of the area into a specific category of the air quality index. The strongest correlation occurs in the fair & moderate AQIPM area. In relation to temperature, there is a negative correlation, and in relation to humidity, positive. In the extremely poor AQIPM area, no relationship was observed between humidity and particulate matter concentration. In the good AQIPM area, the correlation in relation to temperature was very weak, in relation to humidity, weak.

Combustion behavior of solid waste fuels in the vertical tube reactor under different oxy-fuel environments

Oxy-fuel combustion technology has been recognized as one of the promising ways for cost-effective CO2 capture. The co-combustion characteristics of flax straw biomass/bituminous coal mixture (FS/BC) and flax straw biomass/sewage sludge mixture (FS/SS) under air, oxy-fuel (21%/79% O2/CO2) and oxygen-enriched oxy-fuel (30%/70% and 40%/60% O2/CO2) conditions were investigated in the vertical tube reactor. In particular, the study focused on the burning characteristics, the effect of blending ratio, and flue gas emissions. The findings indicated that flax straw biomass exhibited superior ignition performance compared to its blends with sewage sludge and bituminous coal. A higher O2 concentration from 21% to 40 led to a reduction in ignition delay time by 4s at 850 ℃ and by up to 10s at 950 ℃. Moreover, char combustion time was reduced by 50% for FS/SS blends due to the lower fixed carbon content compared to FS/BC blends. Additionally, increasing the O2 concentration resulted in lower emissions of CO by ∽40% and N2O by ∽45% for both blends. However, this also led to a slight increase in SO2 and NO emissions by ∽15% and ∽26%, respectively. The optimal conditions for the tested samples in oxy-fuel environment were found to be 30% O2/70 CO2, which enhanced combustion performance while lowering flue gas emissions.

Aromatic carboxyl acid regulated nanoparticle deposition and passivation of tin oxide for high performance perovskite solar cells

The composition and nano particle agglomeration of hydrolyzed species in chemical bath deposition (CBD) plays a key role in obtaining efficient SnO2 film for high performance perovskite solar cells (PSCs). In this work, the aromatic acids with varied carboxyl groups were investigated to regulate the nano particle deposition and passivate the buried SnO2/perovskite interface. The quasi in-situ dynamic light scattering and Zeta potential results indicated that the nano particle agglomeration with trimesic acid (TMA) was significantly refined throughout the whole deposition process. The TMA-SnO2 achieved an ideal energy band alignment with perovskite and released the internal residual strain, promoting the growth and crystallization of the perovskite film due to the corrdination of carboxyl groups. As a result, the interface defects were effectively passivated with enhanced efficiency and stability. The small area device based on TMA-SnO2 obtained an efficiency of 25.07 %. The devices with an enlarged area of 1.4 cm2 and the 5x5 cm2 mini-module (active area 10.054 cm2) showed impressive PCEs of 23.93 % and 22.40 %, respectively. Furthermore, the unencapsulated devices exhibit enhanced long-term stability, maintaining 80 % and 90 % of the initial efficiencies under 80 ± 5°C thermal annealing in nitrogen for 1176 h and in air condition for 3224 h, respectively.

Enhancing indoor thermal comfort prediction in tropical regions: A transfer learning strategy in West Bengal

Ensuring energy-efficient building management and sustainability necessitates precise thermal comfort prediction, a task particularly critical in tropical regions with significant energy-saving potential. This study confronts the complexities introduced by humid air conditions and escalating internal and external heat levels. The objective is to devise a sophisticated strategy for predicting indoor personal thermal comfort that enhances prediction accuracy. The proposed method extends beyond previous techniques by incorporating a comprehensive array of thermal comfort factors and their potential interdependencies, while also leveraging a transductive transfer learning strategy to circumvent data sparsity in the target domain. The experimental results indicate the presence of localized feature coupling within thermal comfort datasets, which the proposed CNN-ConvTrans model effectively processes, thereby enhancing predictive efficacy. The primary innovation of this work lies in the development of a novel transfer learning strategy that considers localized feature coupling, integrated with a deep learning model, effectively addressing issues such as class imbalance and data scarcity. This study furnishes an innovative and valuable framework for thermal comfort prediction across diverse environmental settings.

Catalytic degradation of stable benzene molecules under room temperature conditions over Pt-loaded boron-carbon-nitride (Pt/BCN) catalysts

The catalytic degradation of volatile organic compounds (VOCs) such as benzene via ring-opening at room temperature is challenging due to the presence of π-bonds in the ring-forming carbon atoms. This study involved the preparation of a novel Pt-loaded boron-carbon-nitride (Pt/BCN) catalyst containing single-atom active sites for efficient catalysis of benzene degradation at room temperature in air. The micromorphology, surface structure, and coordination environment of the catalyst were analyzed using characterization techniques including aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC–HAADF–STEM) and X-ray absorption fine structure (XAFS). The degradation mechanism was investigated using electron paramagnetic resonance (EPR) and in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). The experimental results demonstrate that Pt/BCN contains many Pt-N4 single-atom active sites that can generate hydroxyl radicals under room-temperature air conditions, leading to the oxidation of benzene to CO2 and H2O. Containing atomically dispersed active-site catalysts developed in this study offer a theoretical foundation for designing catalyst active centers in related fields and advancing the industrial application of room-temperature, low-carbon VOCs treatment technologies.

Unprecedented synthesis of indole-linked tetra-substituted alkenes by catalyst-free domino reaction

Herein, we report a simple, efficient catalyst-free green domino reaction of indole, arylglyoxal, and cyclic 1,3-dicarbonyls such as barbituric acid derivatives/dimedone at 100oC in dimethylformamide medium in open air condition. In this reaction, one C-C and one C=C bonds have been formed in one-pot without using any additive or metal based reagent. Considering the presence of indole, benzoyl and cyclic 1,3-dicarbonyl moieties in the products, it is expected that they will exhibit interesting medicinal properties. All the synthesized products were characterized by recording FTIR, 1H NMR, 13C NMR, and HRMS. Moreover, a single crystal XRD of compound 4i was recorded to confirm the structure of the product. Operational simplicity, gram-scale synthesis, mild reaction conditions, good yields, and wide substrate scope are the salient features of this methodology.

Implementation of An Application-Based Motor Vehicle Exhaust Emission Level Detection System

Currently, air conditions on earth are getting worse over time due to the impact of air pollution. One example of air pollution is motor vehicle exhaust emissions. Exhaust gas emissions are the result of combustion residue in motor vehicle engines that use fuel. Motor vehicle exhaust emissions contain carbon monoxide (CO), hydrocarbons (HC), carbon dioxide gas (CO2) which have a negative impact on the environment and living creatures. This research will create a motor vehicle exhaust emission detection device. In this design, an Arduino microcontroller was used and the manufacture of this tool used an MQ-7 gas sensor to detect carbon monoxide (CO) gas, an MQ-2 sensor to detect hydrocarbon gas (HC), and an MQ-135 to detect carbon dioxide (CO2) gas. The emission test results will be sent to the application, this data includes plate number, vehicle type, vehicle brand, vehicle year and emission test results. The results of the carbon monoxide (CO) gas sensor calibration test taken from 5 data showed an error of 5.51%. The results of the hydrocarbon (HC) gas sensor calibration test taken from 5 data showed an error of 4.23%. The results of the carbon dioxide (CO2) gas sensor calibration test taken from 5 data showed an error of 1.06%. In the implementation of the tool and application, the test results were obtained for 15 vehicles. Where the highest hydrocarbon (HC) gas content value was 412 ppm, the highest carbon monoxide (CO) gas content value was 1.48%, and the highest carbon dioxide (CO2) gas content value was 21.4%.

Antisolvent‐Mediated Air Quench for High‐Efficiency Air‐Processed Carbon‐Based Planar Perovskite Solar Cells

Perovskite solar cells (PSCs) have emerged as a leading low‐cost photovoltaic technology, achieving power conversion efficiencies (PCEs) of up to 26.1%. However, their commercialization is hindered by stability issues and the need for controlled processing environments. Carbon‐electrode‐based PSCs (C‐PSCs) offer enhanced stability and cost‐effectiveness compared to traditional metal‐electrode PSCs, i.e., Au and Ag. However, processing challenges persist, particularly in air conditions where moisture sensitivity poses a significant hurdle. Herein, a novel air processing technique is presented for planar C‐PSCs that incorporates antisolvent vapors, such as chlorobenzene, into a controlled air‐quenching process. This method effectively mitigates moisture‐induced instability, resulting in champion PCEs exceeding 20% and robust stability under ambient conditions. The approach retains 80% of initial efficiency after 30 h of operation at maximum power point without encapsulation. This antisolvent‐mediated air‐quenching technique represents a significant advancement in the scalable production of C‐PSCs, paving the way for future large‐scale deployment.

Transient behavior of ablation and swelling for C/C composite and HfC-coated C/C composite in an arc-heated wind tunnel

This study investigated and modeled the transient behavior of surface recession, defined as the difference between ablative length and swelling length, for thermal protection materials within a high-enthalpy flow. Needle punch carbon-carbon (NPCC) and hafnium carbide coated carbon-carbon (HfC-coated NPCC) were exposed to high-enthalpy flow with a heat flux of 7.67 MW/m2 generated by an arc-heated facility. The NPCC and the HfC-coated NPCC represent an ablative surface and a non-ablative surface, respectively. Surface recession histories were estimated through an image analysis and visualizations monitored by a high-speed camera. Moreover, measured data including surface temperature histories, mass loss, and total length were presented. We proposed the models for the transient recession on the ablative surface and the non-ablative surface considering the ablation and the swelling. The ablative length was calculated using non-dimensional parameter B′, which computes ablation rates under equilibrium air conditions. While B’ modeling accurately predicted the ablation rates, it could not reflect the swelling phenomenon during an initial heating phase. The swelling was modeled with consideration of the thermal expansion. Specifically, the effect of increased porosity near the ablative surface was incorporated into the thermal expansion coefficient. The model developed in this study well agreed with the experimental data.

Numerical study on parametric correlations and regional applicability of a cross-flow indirect evaporative cooler

The indirect Evaporative Cooler (IEC) utilizes exhaust air from air-conditioned spaces to precondition outdoor air, offering a low-carbon and efficient solution for cooling the air and expanding its application scope. This study developed a mathematical model of IEC, considering the effects of primary air condensation and channel wettability. The correlations of eight parameters on evaluation indexes were analyzed to rank their influence for IEC, revealing that outdoor climate, indoor air conditions, geometric shape, and channel wettability are the main factors affecting cooling efficiency and energy recovery capacity. Subsequently, a comparison of the temperature and humidity distribution inside the IEC under high and low wettability showed that under high-wettability, the cooling effect of the IEC for primary air increased by 23.7 %, and the dehumidification capacity improved by 52.9 %. The performance study of the IEC across seven geographical regions in China indicates that cities with a wet-bulb efficiency greater than 45 % are predominantly located in Northwest China and North China. East China, Central China, and South China exhibit significantly higher average condensation coefficients and cooling capacities compared to other areas, with values of 2.36, 2.26, and 2.56 for the condensation coefficients, and 14.2 kW, 14.7 kW, and 14.9 kW for the cooling capacities, respectively.

Enhancing lubrication of electrified interfaces by inert gas atmosphere

Abstract Considering the growing interest in increasing performance and efficiency of driveline components of modern electric vehicles, this work aims to analyze and report the wear mechanisms and notable enhancement of the lubrication of electrified contact interfaces by inert gas atmospheres. Systematic tribological studies were conducted on AISI 52100 steel test pairs using driveline lubricants under unelectrified and electrified conditions in ambient air and dry N2. Test results showed that in ambient air and electrification, the formation of iron oxides (in particular hematite) was most dominant and gave rise to severe abrasive wear regardless of the lubricant type being used. In dry N2, however, the tribo-oxidation was suppressed but the formation of a carbon-rich tribofilm was favored (especially under electrified conditions). Such a shift from surface oxidation to carbonaceous film formation resulted in dramatic reductions (by factors of 8 to 10) in the wear of test pairs.

Enhanced protonic and oxygen-ionic conductivity in Ga-doped Nd2Ce2O7 electrolytes for intermediate-temperature solid oxide fuel cell

Developing mixed oxygen-ion and proton conductors with high ionic conductivity is crucial for advancing intermediate temperature-solid oxide fuel cell (IT-SOFC). In this study, a novel Nd2-xGaxCe2O7 (NGCO, x = 0, 0.05, 0.075, 0.10 and 0.15) ceramic is synthesized by the citric acid-nitrate sol-gel combustion process. The influence of Ga doping on crystal structure, oxygen vacancy, morphology, proton transport characteristic and electrochemical performance of this materials is systematically investigated. It is found that the NGCO exhibits the fluorite-type structure and belongs to space group Fm3¯m. NGCO shows remarkable chemical stability, resisting harmful effects from CO2, water, and wet hydrogen exposure. Adding a small amount of Ga results in high-density ceramics with enlarged grain size and reduced grain boundary density. Nd1.925Ga0.075Ce2O7 (7.5NGCO) displays outstanding conductivities, exceeding Nd2Ce2O7 (NCO) by 271.4% and 248.6% in dry air and wet hydrogen conditions. Further, an anode-supported structure fuel cell with 7.5NGCO electrolyte is constructed and evaluated. The peak power density (PPD) at 700 °C reaches 702 mW/cm2, a 96% enhancement over the fuel cells with NCO electrolyte. These findings indicate that Ga-doped NCO electrolyte holds promise as a proton-conducting electrolyte suitable for IT-SOFC.

Direct patterning of electrical wiring on three-dimensional plastic substrate under ambient air conditions

Direct patterning of electrical wiring on three-dimensional plastic substrate under ambient air conditions

Dust Pollution in Construction Sites in Point-Pattern Housing Development

Construction in cities and agglomerations is one of the main sources of air pollution in most countries in the world. Fine dust particles, PM0.5–PM10, which form as a result of construction processes, are among the most dangerous pollutants. With the increase in the volume of point-pattern housing development in cities, the task of maintaining clean air and environmental conditions becomes important. This requires research, the monitoring of dust emissions throughout the entire construction period and the development of design solutions based on the results obtained. The study examines the determination of the dispersed composition of dust generated on a construction site. A graphical representation of the dispersed composition is given by constructing integral curves on a logarithmic grid and approximating them using two-link and three-link splines. The gravimetric measurement method was used to analyze the concentration of dust in the air released during construction work near residential areas. Dust analysis at the construction site revealed significant differences in particle size that cannot be explained by statistical errors alone. The reasons for this are both working conditions and climatic factors, including humidity and wind intensity. In this regard, it is preferable to use models that take into account random processes instead of traditional deterministic methods to study the dust that shapes during construction.

Improving the air condition of vehicle cabins

Improving the air condition of vehicle cabins

Effect of feeding amount on tail gas and waste salt obtained from molten salt oxidation process of cation exchange resins

ABSTRACT The effective treatment of spent radioactive ion exchange resins generated during the operation of nuclear facilities is of great significance to reduce its potential hazards to the environment. This work innovatively provides a simple and low-cost molten salt oxidation (MSO) system includes air intake, feeding, waste salt discharge and exhaust gas treatment and analysis system for disposal of spent cation exchange resins (CERs). By studying three feeding amounts that injection of 25 g, 125 g and 1250 g CERs in 10 times under air conditions, the oxidation efficiency of CERs in MSO system was further evaluated. The scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) results indicated the sulfur can be trapped in the melt. Sulfur in functional group can be converted to Na2S and KLi(SO4) via Li2CO3-Na2CO3-K2CO3, which is proved by XRD patterns. The experimental results presented that degradation rates of CERs are 99.31%, 99.80%, and 99.91% in different feeding amounts, respectively. Furthermore, the volume reduction of residue gathered by feeding 1250 g CERs in 10 times was the highest, which can reach 9.19. Therefore, the bench-scale MSO system is a potential and promising treatment for spent CERs volume reduction.

Evaluation of the influence of climatic changes on the degradation of the historic buildings

While climatic change has been a widely studied topic, its impact on cultural heritage degradation remains a gap to overcome. The environment can contribute to the degradation of historic buildings and materials decay, especially temperature and humidity. So, characterizing the micro-climates of a landmark zone and understanding the influence of the recovery layers, building disposition, and street characteristics on environmental parameters are the first steps to investigating resilience strategies for heritage conservation and micro-climates. Thus, this paper presents a new approach to assess the influence of climatic warming on historic building degradation, combining multiscale experimental data and numerical modeling. The environmental parameters of the historic center of Aracati downtown, such as concentration of CO2, relative humidity, temperature, and air condition, were characterized and used together with urban volumetry to discuss the influence of on the urban microclimate and relate the data to the physical degradation of cultural heritage. An uncrewed aerial vehicle was used to register the volumetry of the historic center, and the data was used to simulate the wind conditions. Following this, numerical analysis was used to investigate the rising damp and thermal tension distributions under temperature variation over the years (from 2023 to 2100). The methodology’s applicability was demonstrated in recurrence with the Nosso Senhor do Bonfim Church, one of the most representative heritage constructions from Aracati downtown. Finally, the new methodology contributed to understanding how urban volumetry contributes to the climatic conditions of a historic area and demonstrates that the increase of the temperature can significantly affect the rising damps and the development of stress tension.

Electrooxidative Ni-catalyzed Decarboxylation of Arylacetic Acids towards the Synthesis of carbonyls under Air Conditions.

After systematic realization of decarboxylative functionalization of carboxylic acids under heating conditions in our group, we herein reported an electrochemical method for Ni-catalyzed decarboxylative oxygenation of arylacetic acids under open air conditions. The protocol provided corresponding carbonyls including aldehydes and ketones in moderate to satisfactory yields with good functional group tolerance, furthermore, the practicability and advantage of the method was highlighted through Ni-catalyzed oxidative decarboxylation of carboxylic acid-containing drugs and preformation of scalable transformation. Mechanistic studies demonstrated that the possible involvement of free radical intermediate in the conversion.

Isostructural Oxamate Complexes with Visible Luminescence (Eu3+) and Field-Induced Single-Molecule Magnet (Nd3+).

The search for new metal-organic compounds as candidates for quantum information processing technologies is in the spotlight. Several metal ions and organic linkers have been used to obtain such compounds. Herein, we describe the synthesis, crystal structures, and cryomagnetic properties of two air-stable isostructural neodymium(III) and europium(III) one-dimensional (1D) coordination polymers of formula [Nd(Hmpa)3(DMSO)2]n (1) and [Eu(Hmpa)3(DMSO)2]n (2) [Hmpa = N-(4-methylphenyl)oxamate, and DMSO = dimethylsulfoxide]. These complexes were prepared by reacting n-Bu4N(Hmpa) proligand [n-Bu4N+ = tetra-n-butylammonium] and the correspondent LnCl3·6H2O salt (Ln = Nd or Eu) in the open air and mild conditions. The crystal structures of 1 and 2 reveal the Ln3+ ion surrounded by two DMSO molecules and three oxamate ligands, one of them connecting to adjacent mononuclear entities through carboxylate bridges featuring a 1D coordination polymer, while the other two establishing double N-H···O hydrogen bonds among adjacent polymers to give a resultant supramolecular 2D network. Cryomagnetic measurements in the static (dc) and dynamic current (ac) regimes reveal that 1 behaves as a field-induced single-molecule magnet below 8.8 K. A photoluminescence study shows that Hmpa ligands efficiently sensitize the luminescence of Eu3+ complex in the visible region in the solid state at room temperature.