Oily aerosols have emerged as a concerning pollutant in modern built environments, and their associated health risks necessitate attention. Thus, effective reduction of indoor oily aerosols concentrations is necessary. As a primary method for air purification, porous media filtration encounters significant challenges in treating oily aerosols. The aerosols tend to coalesce into liquid films that progressively bridge and block pore throats, causing rapid flow resistance and a sharp rise in pressure drop with increased energy consumption. Moreover, the high viscosity of oily aerosols hinders effective removal during cleaning, further complicating filter regeneration and raising life cycle costs. This review systematically summarizes recent advances in oily aerosol filtration research. It begins by examining how the physical properties of oily aerosols—including particle size, surface tension, and viscosity—affect their dynamic behavior within filter media. The analysis then reviews strategies for reducing pressure drop through filter media optimization, focusing particularly on surface wettability regulation and structural design. Advances in regenerative filter media are also discussed. Based on the synthesized review of existing studies, this work identifies key unresolved challenges in current oily aerosol filtration research and points to the development of sustainable and practically applicable filter media as a critical direction for future investigation.

Long-term exposure to high concentrations of metal welding fumes is a major cause of occupational respiratory diseases such as occupational asthma and pneumoconiosis. To comprehensively assess the health effects of welding dust on workers, this study conducted field measurements in a welding workshop of a mechanical and electrical processing plant in Shaanxi Province. The multi-dimensional characteristics and oxidative potential of metal welding dust were analyzed. By using a breathing thermal manikin equipped with an idealized respiratory tract model, internal respiratory tract exposure data were obtained, revealing the relationship between external exposure in the breathing zone and internal respiratory tract exposure.The results suggest that oxidative potential is related to mass concentration, particle size and chemical composition. Internal respiratory tract exposure demonstrates higher oxidative potential and a stronger correlation with oxidative potential than external exposure. Different chemical components contribute differently to oxidative potential; zinc (Zn), barium (Ba), sodium (Na) and sulphur (S) show the strongest correlations.Environmental control measures in metal welding workplaces should consider the multi-dimensional effects of dust. Incorporating dust oxidative potential is recommended to better reflect the health risks to workers, thereby achieving truly health-oriented and precise prevention and control.

Efficient gas-liquid atomization is crucial for dust control and occupational health protection in building and industrial environments. However, the complex coupling effects of ambient airflow parameters (temperature, velocity, and angle) often cause spray characteristics to deviate from design expectations, thereby reducing dust suppression efficiency. To address this, this study innovatively employs experiments, numerical simulation, and explainable machine learning (ML) to clarify the atomization differences between two typical nozzles, reveal the influence mechanisms of nozzle geometry and ambient parameters on atomization, and validate the feasibility of the data-driven approach for dust control. Results indicate that under identical pressure, a cap-assisted nozzle yields droplet size, axial velocity, and spray angle 1.58, 3, and 7.64 times greater, respectively, than a straight-through nozzle, demonstrating enhanced adjustability. For this nozzle, the LightGBM algorithm optimally predicted droplet size, achieving R-2 >= 0.818 on the test set. Airflow temperature (T), liquid-injection orifice diameter (Dl), and exit diameter (D-e) are identified as the dominant factors affecting the Sauter mean diameter (D-32). The effect of T on D-32 follows three stages: from breakup-dominated to evaporation-dominated, then to dynamic equilibrium. At high temperatures (>800 K), the optimal D(l )range narrows by approximately 50% compared to room/moderate conditions (<600 K). A configuration with Dl < 1.40 mm and D-e < 3.25 mm effectively balances anti-clogging performance and atomization quality, achieving a dust suppression efficiency of 85.24% in experimental validation. This work provides theoretical and methodological insights for designing high-performance nozzles in complex built-environment flow fields.

Metallurgical industrial processes often generate intermittent high-temperature buoyant jet laden with particulate matter, whose flow rates vary in a pulsating manner, posing considerable challenges to the control of ventilation systems. The use of an expanded volume exhaust hood (EVEH) enables the storage of excess airflow during peak stage, thereby alleviating the exhaust load on ventilation systems. Nevertheless, the parametric design and performance evaluation indicators for EVEH have not yet been clearly defined. Based on the evaluation index of dynamic capture efficiency and transient CFD, this study systematically investigates the effects of flow ratio, source intensity, and hood size on the performance of EVEH in controlling intermittent high-temperature buoyant jet, and proposes specific design parameters for the EVEH. The results show that when controlling process, vortices conducive to airflow storage form inside the EVEH, whose evolution can be divided into three stages: generation, splitting and growth, and attenuation. Reducing the flow ratio and decreasing the hood size both enhance the storage effect of vortices. In addition, an increase in source temperature further improves the storage performance. When flow ratio ε ≤ 1.8 and hood size 0.75 ≤ L ≤ 1.0, the EVEH can play a positive storage role at lower drag. Based on the optimal flow ratio, a prediction formula for the maximum storage efficiency is fitted, with a maximum storage efficiency of about 12%~15% and a total capture efficiency greater than 99%. These findings provide theoretical guidance for the optimal design of EVEH in industrial building environment control.

Low pressure loss and uniform airflow distribution are essential for improving the energy efficiency and indoor air quality of ventilation systems. However, traditional tee flow equalizers are prone to flow separation, recirculation, and strong shear effects in the convergence zone, leading to increased energy dissipation, elevated pressure drop, and uneven velocity distributions at the outlet. To address these issues, this paper presents a three-dimensional topology optimization method based on the level set method combined with discrete adjoint sensitivity analysis for the structural design of tee flow equalizers. This approach aims to synergistically reduce the pressure drop while increasing the outlet flow uniformity. A multi-objective optimization function balancing pressure drop and outlet velocity deviation is constructed, and the effects of turbulence models and weighting factors on the optimization results are analyzed. The results demonstrate that a continuous, smooth primary flow channel gradually forms during topology evolution, effectively suppressing flow separation and recirculation. Under various flow ratios, the optimized flow equalizer consistently exhibits excellent performance: the maximum improvement rates of resistance in the straight-through and branch directions are 107.6% and 155.7%, respectively. When the flow ratio is 0.7, the maximum improvement in uniformity index is 23.5%. Analysis of the flow field and entropy production reveals that performance improvement stems from the reduction of velocity and pressure gradient. The experimental results are in good agreement with the numerical simulations, validating the effectiveness and engineering applicability of the proposed method. The proposed approach offers insights for the design of low-pressure-loss flow equalizer devices.

With external pollution controlled, internal nutrient released from the sediment has become the driving factor to eutrophication, which also turned urban shallow waters from greenhouse gas (GHG) sinks into sources. Calcium peroxide (CP) and sponge iron (SI) are green materials for water and sediment remediation, but their synergistic mechanisms in concurrent abatement of endogenous pollution and GHG emissions via different co-dosing modes remain unclear. This study applied CP-SI composite via covering and suspending to investigate effects on water quality, sediment properties, microbial community structure, and GHG emissions. Results indicated that the dosing mode decisively regulated sediment redox conditions, iron-sulfur cycling and microbial functions. Both modes effectively removed total phosphorus (TP) from overlying water (coverage: 82.55 %; suspension: 71.52 %), COD and GHG emissions control. Its core mechanism is the synergistic effect of the iron-sulfur cycle and Fenton-like reactions, promoting sustained release, increasing Desulfatiglans abundance by 1.6-fold and maintaining high activities of catalase (CAT) and dehydrogenase (DHA), to mitigate NH+4 -N concentration and GHG emissions. In contrast, coverage mode weakened iron-sulfur cycling, raising NH+4 -N (12.25 mg/L) and COD (23.01 mg/L) in the overlying water, generating excessive center dot OH to degrade organic matter and induce a 6.67-fold increase in sediment volatile fatty acids, which consequently promotes GHG emissions. In conclusion, the suspension mode performs more comprehensively in controlling internal nutrient release and GHG reduction, and this study thereby provides a theoretical basis and technical reference for the simultaneous regulation of these two processes in water bodies.

In cold regions, winter operation of local exhaust ventilation (LEV) in industrial buildings must balance effective pollutant capture against the high heating penalty caused by exhaust-induced negative pressure and outdoor cold-air infiltration. This study compares outdoor-air circulation (OAC), indoor-air circulation (IAC), and conventional exhaust-only ventilation (EOV) for an industrial workshop in a severe cold region. Validated CFD simulations, supported by experiments, were used to assess indoor thermal environment and energy performance under the constraints of a local exhaust hood capture efficiency of at least 98% and a workplace H2S concentration below 10 mg/m & sup3;. Two IAC cases with purification efficiencies of 96% and 100%, denoted as IAC (96) and IAC (100), were considered. For OAC, an orthogonal screening design combined with flow-field and pollutant-distribution analyses was used to assess key make-up air parameters. Within the investigated outdoor-temperature range of -19 degrees C to -5 degrees C, total energy consumption follows the order of IAC (100) < OAC < IAC (96) < EOV, and the energy-saving advantages of IAC and OAC over EOV increase as outdoor temperature decreases. The make-up air ratio was the most influential OAC parameter. At a make-up air ratio of 80%, OAC reduced heating-energy demand by 26%-28% relative to EOV under the same capture-efficiency requirement.

Asymmetric heat sources common in metal rolling lines generate complex thermal plumes that hinder efficiently capturing oil mist emissions. Matching the local ventilation system to the specific heat source characteristics is critical for efficient pollutant capture and reduced energy consumption. This study employs a numerical method to clarify plume behavior and to optimize local exhaust hood design for a representative cylindrical coil and flat strip configuration commonly found in industrial rolling production lines. The results indicate that owing to the asymmetrical heat source configuration, the plume over the sources exhibits a bimodal asymmetric distribution on the constrained side and a triple-peak symmetric distribution on the unconstrained side. A power-law correlation relates capture efficiency eta to exhaust airflow rate Q and the source-to-ambient temperature difference Delta T, enabling rapid sizing of exhaust systems. Guided by these insights, an annular hood was modified by adding slots and redistributing flow (Q1 : Q2 = 0.95 : 1.05) to match with plume peaks. Performance and economic analyses of the exhaust hood indicate that an optimal airflow distribution ratio can reduce oil mist particle escape rates by 26-50 % and achieve lower fan energy consumption by up to 42.7 %. The findings provide a quantitative basis for designing energy-efficient ventilation systems that address the unique plume structures produced by asymmetrical heat sources, and they are transferable to similar rolling and heat-processing operations.

Under calm and stable weather, an urban heat island circulation (UHIC) is formed driven by the thermal pressure of the urban heat island, which is vital for air change and pollutant transport between the urban canopy layer and the background air. In this paper, the evolution of the UHIC for the flat city is investigated using a city-scale computational fluid dynamics (CSCFD) model. The CSCFD model can consider the atmospheric compressibility and thermal stratification in the basic equations. The simulation results show that the evolution can be divided into the transient and quasi-steady stages. During the transient stage the flow pattern of the UHIC is mainly in the form of the thermal convection, while the flow pattern of the UHIC during the quasi-steady stage is the city-scale closed circulation. The nondimensional start time of the city-scale closed circulation shows an inversely proportional function to Fr (tN = 2.172/Fr), and the nondimensional mixing height of the UHIC shows a positively proportional function to Fr (zic/D = 2.80Fr). The sensitivity analysis reveals that the factors influencing the start time of the city-scale closed circulation include, in order of significance, urban diameter > urban heat flux > potential temperature lapse rate, while the factors influencing the mixing height in the quasi-steady stage include, in order of significance, potential temperature lapse rate > urban diameter > urban heat flux. This study provides theoretical bases for the control of industrial activities during critical meteorological periods, and the operation of water tank experiments.

This experiment aimed to investigate the effects of different moisture content on the nutritional components, fermentation quality, and amino acid content of corn straw silage under consistent harvest conditions. Corn straw was adjusted to moisture contents of 60% (group W1), 65% (group W2), 70% (group W3), and 75% (group W4), then ensiled. Each group had six replicates and was ensiled for 30 days. The results showed that in terms of sensory evaluation, group W2 performed the best, while group W4 performed the worst. Regarding nutritional components, as the moisture content increased, the temperature showed an upward trend but the difference was not significant (P>0.05). The concentrations of crude protein and starch significantly decreased (P<0.05), the content of neutral detergent fiber significantly increased (P<0.05). The content of acidic detergent fiber increased, and the group W2 was significantly lower than the group W4 (P<0.05). In terms of fermentation quality, the pH value of groups W3 and W4 was significantly higher than those of groups W1 and W2 (P<0.05). The lactic acid content of group W2 was significantly higher than that of the other groups (P<0.05). The acetic acid content of groups W3 and W4 was significantly higher than that of groups W1 and W2 (P<0.05). The propionic acid content of groups W1 and W4 was significantly higher than that of groups W2 and W3 (P<0.05). The butyric acid content of group W4 was significantly higher than that of the other groups (P<0.05). The ammonium nitrogen content of group W4 was significantly higher than that of group W2 (P<0.05). The histamine content of group W3 was significantly higher than that of the other groups (P<0.05). Regarding amino acid content, the essential amino acid to total amino acid ratio (EAA/TAA) of group W2 was significantly lower than that of groups W3 and W4 (P<0.05). Lysine (Lys), isoleucine (Ile), valine (Val), phenylalanine (Phe), leucine (Leu), and tryptophan (Try) showed a trend of first increasing and then decreasing, with group W2 had the highest content, significantly higher than those of group W4 (P<0.05). The study shows that excessively high moisture content can easily lead to abnormal fermentation, while excessively low moisture content results in insufficient fermentation. An appropriate moisture content (65%) is conducive to promoting the proliferation of lactic acid bacteria, improving fermentation quality, and enhancing the nutritional value of the silage.

In practical vortex ventilation systems for large-space industrial buildings, vertical spatial constraints often force supply inlets to be installed near the ground, far from roof exhaust outlets. This prevents the angular momentum of the supply jets from effectively reaching the exhaust zone, thus hindering the formation of a stable vortex. To address this, a fan-shaped air-supply vortex ventilation system (FAVV) is proposed to optimize the spatial distribution and transfer path of angular momentum. The influence of key parameters-supply angle (theta), horizontal deflection angle (alpha), and supply airflow rate (Q(s))-on capture efficiency (eta) is investigated using orthogonal experiments and computational fluid dynamics (CFD) simulations. Further analysis of flow field characteristics is conducted based on the significant parameters identified. The results indicate that theta, alpha, and Q(s) significantly affect eta, in the order of theta> alpha > Q(s). The capture efficiency increases with theta until reaching a plateau, while it shows a peak trend with increasing alpha and Q(s). Notably, excessively high Q(s) can reduce eta even at optimal theta and alpha. Compared to the traditional circular air-supply vortex ventilation (CAVV), FAVV enhances the vortex's pressure gradient and velocity components, improving airflow convergence and pollutant transport. On average, FAVV increases capture efficiency by 4.76%, with the most significant improvement (5.83%) observed for 25 mu m particles.

Total petroleum hydrocarbon (TPH) pollution in the sediments of urban landscape water (ULW) threatens the health of aquatic ecosystem, but the effective in-situ remediation remains limited. To address this gap, this paper systematically studied calcium peroxide (CaO2) by comparing two delivery modes (covering and injection) and two dosage levels (0.3 and 0.4 kg/m2), as the interplay between oxygen distribution and dosage critically determines the field applicability. Injection of 0.4 kg/m2 achieved the optimal performance, reducing sediment TPH from 56.0 to 11.3 g/kg (79.8% removal) with extensive high-molecular-weight alkane degradation. Mechanistically, injection surpassed covering by delivering oxygen directly into contaminated sediment strata, thereby circumventing the diffusion bottleneck inherent to surface amendment. Further investigations revealed that CaO2 injection mainly exerted remediation via microenvironmental modulation: elevating dissolved oxygen (DO), stabilizing pH within a biocompatible range via sediment buffering capacity, regulating volatile fatty acids (VFAs) and promoting sulfur oxidation while suppressing anaerobic fermentation. These physicochemical shifts induced directional microbial community succession, enriching aerobic hydrocarbon-degrading taxa (e.g., Silanimonas, Rubrivivax, and Comamonadaceae). FAPROTAX functional annotation indicated remarkable enhancement of aerobic chemoheterotrophic metabolism, which sustained continuous TPH biodegradation. Notably, CaO2 injection imposed minimal adverse impacts on overlying water, demonstrating great potential for practical engineering. Collectively, CaO2 injection as a promising strategy was proposed in this study for in-situ remediation of TPH-contaminated sediments in ULW, which could provide the theoretical frameworks and technical references for remediation of TPH-contaminated sediments in the analogous aquatic systems.

In industrial environments, the composite plate-cylinder heat source (CPCHS), characterized by multi-body geometries and moving boundaries, is ubiquitous in various high temperature processes like metal rolling and other processes involving rotating and translating components, and serves as the primary driving force for pollutant dispersion within workshops. Unlike classical regular sources, CPCHS exhibits significant geometric asymmetry and thermal interference, coupled with intense wall shear during processes, resulting in a complex plume evolution mechanism. This study employs steady RANS and unsteady LES to investigate the plume structure, entrainment, and flow evolution of CPCHS under both quiescent and sheared environments. Results indicate that the composite configurations significantly reshape flow behaviors. In a quiescent condition, compared to the rectangular plate, CPCHS-I (cylinder-below-plate) increases plume volume flow rate by 40% and spreading radius by 25%. Notably, CPCHS-II (cylinder-above-plate) shows a 92% flow rate surge and a 35% spreading radius increase due to a dual-core merging effect. Upon introducing wall shear effect, LES results reveal that shear forces disrupt the stable coherent structures observed in quiescent states, inducing fragmented and disordered vortex patterns. This instability not only deflects plume trajectories but also causes a substantial surge in plume flow rate by enhancing near-field turbulent mixing. Power-law scaling laws correlating the bulk Ri with plume flow rate at z/l* = 2.5 were established. These models quantify the shear enhancement effects, correcting limitations in traditional designs that neglect shear and providing a theoretical basis for optimized local ventilation in complex industrial settings.

Modern machining workshops commonly face two major challenges: VOCs and oil droplet pollution, and excessively high energy consumption for environmental control. Efficiently improving the workshop environment and reducing energy consumption for environmental control is crucial for achieving sustainable operation of industrial buildings. Using large eddy simulation, this study first reveals the influence of the Richardson number (Ri) on the flow development of intermittently airflow and the dispersion of two-phase pollutant. In low-Ri conditions, intense entrainment occurs at the flow edge with the surrounding air, promoting pollutant dispersion; when Ri ≤ 0.98, the horizontal dispersion range of both VOCs and oil droplets can reach 1.9 times the equivalent diameter of the pollution source (dp). In contrast, the interaction between high-Ri airflow (Ri ≥ 29.4) and the surrounding air manifests as mild shear, resulting in relatively limited diffusion ranges for VOCs and oil droplets, at 1.3 dp and 1.2 dp, respectively. Then, the study also found that when 0.16 ≤ Ri ≤ 117.6, significant gas-droplet separation of VOCs and oil droplets typically does not occur within a height range of 5 meters above the source, creating conditions for the synergistic control of two-phase pollutants. Finally, the study proposes a near-field environmental control method using VOCs-Oils Synergistic Purifiers (VOSP). Compared with increasing the air changes rate, using VOSP not only ensures that the air quality in the worker breathing zone meets NIOSH standards, but also saves 48% of energy consumption annually. The research findings contributes to improving industrial building environments and saving energy.

Urban ventilation is an effective means of improving air quality and promoting sustainable development of urban areas. For Loess Tableland valley towns dependent on heavy industry, the ventilation characteristics of the town area are poorly understood. Therefore, it is important to first explore wind field characteristics over the negative terrain. In this study, the wind field over the negative terrain under the stable background wind was investigated by orthogonal experiments. Simulation results show that airflow patterns in the valley space can be classified into five categories, which are the unstructured flow, combination of unstructured flow and circulation organization, circulation organization, combination of circulation organization and background wind and background wind. The airflow pattern can affect significantly the vertical distribution of the velocity, temperature and air age in the valley space, and thus affecting the ventilation performance of the valley towns. Ventilation performance of valley towns was worse under the unstructured flow conditions, while it was optimal under the background wind conditions. Additionally, sensitivities of terrain factors influencing ventilation evaluation indices at the pedestrian level were analysed. The present study has provided a scientific basis for town planning and industrial emissions in the valley towns.

Oil mist pollution generated in metal processing and rolling facilities poses significant risks to occupational health, equipment reliability, and workshop cleanliness. Rolling mills are typical high-emission environments, where oil mist is released in three distinct zones: the uncoiling, rolling, and recoiling areas. Efficient control of these emissions relies on precise airflow distribution among the three zones; however, this is difficult to achieve during system design because the resistance characteristics of the irregular annular and sealed exhaust hoods are not available. This study quantitatively determines the resistance characteristics of these hoods and reveals their sensitivity to geometrical parameters. Single-factor analyses show that the resistance coefficient of the annular exhaust hood decreases exponentially with the inlet-outlet area ratio, whereas that of the sealed hood increases as a cubic function of the inlet-to-outlet area ratio within the investigated range. Based on these findings, a Box-Behnken response surface model is developed to construct a continuous resistance surface for the annular hood, and a coupled quadratic model is further proposed to directly relate hood geometry to airflow distribution among the three zones. Model predictions agree with simulation results within a deviation of <= 5%, enabling an inverse design method for exhaust systems in rolling mills. Once the desired distribution ratios are specified, the required geometric dimensions of the hoods can be directly determined, avoiding iterative field balancing and improving design-stage accuracy.

Straight-through baghouse dust collectors are used for fine particulate control in industrial processes. However, flow instability inside the housing can trigger separation vortices that intensify local energy dissipation, accelerate premature filter bag wear, and degrade energy efficiency. To achieve flow equalization while retaining the low-resistance advantage of straight-through configurations, this study proposes a synergistic optimization of filter bag arrangement and shape guided by vortex-structure-based flow reconstruction. Two-dimensional simulations show that a stepped filter bag arrangement reduces vortex intensity by 70%, and replacing circular bags with elliptical bags further reduces vortex intensity by 74%. Three-dimensional simulations confirm that combining the stepped arrangement with elliptical filter bags substantially improves airflow distribution uniformity, decreasing the non-uniformity coefficient from 13% to 2%. Performance at four representative operating stages is evaluated in terms of airflow uniformity, dust distribution uniformity, pressure drop, and energy efficiency. The optimized configuration maintains airflow non-uniformity below 5% and dust distribution non-uniformity below 6.5% while reducing the pressure drop by 15% and improving energy efficiency by more than 10%. These results demonstrate that the proposed synergistic optimization strategy provides an effective and practical route for performance enhancement and structural refinement of straight-through baghouse dust collectors.

The air balancing performance of ventilation systems depends on the accuracy of resistance calculations and the regulation characteristics of dampers. The traditional Darcy-Weisbach framework does not account for Reynolds-number effects and coupling between adjacent fittings, making it inadequate for accurately representing actual flow resistance. In addition, the working flow characteristics of dampers may shift under varying operating conditions. To address these issues, this study proposes an intelligent air balancing method suitable for non-fully turbulent flow conditions and coupling between adjacent fittings. A pressure-balance model that accounts for Reynolds number effects and coupling between adjacent fittings is first established, and its parameters are subsequently identified using linear support vector machine (SVM). A random-forest-based prediction model is then employed to estimate the fan static pressure and damper adjustment angles required to achieve the target airflow distribution. Validation experiments were conducted on a full-scale four-branch platform. The proposed method achieved the desired airflow distribution, with an average relative error of 4.83% and a maximum absolute percentage error of 8.21%. The method therefore satisfies ASHRAE accuracy requirements for air balancing. This method provides a feasible approach for intelligent airflow regulation in ventilation and air-conditioning systems under complex operating conditions.

The aerodynamic performance of industrial flow components is crucial in fluid transport systems in buildings, such as Heating, Ventilation and Air Conditioning (HVAC) systems, as excessive flow resistance can lead to increased pressure loss. Most of the existing low-resistance design topology optimization (TO) methods for building fluid distribution systems are based on two-dimensional models, ignoring the resistance in the thickness direction, which limits the optimization accuracy. We propose a pseudo-3D TO method. The nonlinear turbulent friction source term is incorporated into the Navier–Stokes equations to account for friction from the top and bottom walls of the corresponding three-dimensional flow channel, thereby capturing out-of-plane wall-friction effects in the two-dimensional model. The pressure loss coefficient and energy dissipation are set as multi-objectives, comprehensively characterizing resistance through boundary pressure drop and internal viscous dissipation. Z-bend verification shows that the pseudo-3D objective value is 5% lower than the traditional model value and deviates by only 4.5% from the full 3D result. The optimal Z-bend maintained a resistance reduction of 78-81% at different Reynolds numbers and aspect ratios. This pseudo 3D TO method overcomes the limitations of 2D models and provides an approach for low resistance design of industrial flow components. Yan Tian and colleagues propose a pseudo-three-dimensional topology optimization framework for resistance reduction in Z-bend channels. The results show that considering the assumed channel thickness improves the transferability of two-dimensional optimized designs to three-dimensional flow structures.

Metalworking fluids (MWFs) comprise base oils, water, and additives and are widely used in machining. Oil mist generated during machining poses health risks, yet the transformations of MWFs components during inhalation exposure and component-related toxicity differences remain poorly understood. This study aims to identify key exposure components of oil mist and quantify component-related health risks using an evaporation model and oxidative potential (OP). The evaporation model showed that both water- and oil-based MWFs droplets rapidly (0.1-60 s) evolved into water-free oil droplets, indicating that base oils and additives dominated inhalation exposure. OP was measured for three MWFs containing different base oils or additives. OP was associated with both mass concentration and MWFs composition. Mineral oil-based MWFs exhibited relatively higher OP below 0.5 mg/m³ , whereas OP differences among the three MWFs narrowed at 2 mg/m³ . At approximately 5 mg/m³ , the additive-containing MWFs showed a sharp increase in OP, likely due to redox-active substances in additives. These findings demonstrate that MWFs composition significantly affects the oxidative stress-related health risks of oil mist, especially those associated with highly oxidizing additives. This study provides a basis for occupational exposure risk assessment of MWFs oil mist.