Air Diffusion Research Articles

Underground compressed air energy storage (CAES) in naturally fractured depleted oil reservoir: Influence of Fracture

In the last decade, the sources of clean energy supply to meet human needs have been given much attention by researchers worldwide. Compressed air storage in underground formations is an excellent way to balance energy production and consumption. During off-peak hours, with the consumption of excess electrical energy, the air is temporarily stored at high pressure in the desired environment. The stored compressed air produces recovered electrical power during the needed hours and peak energy consumption. Compressed air energy storage in underground structures, including depleted hydrocarbon reservoirs, due to having a suitable storage capacity for air and because their geological characteristics have already been well identified, is one of the storage methods. In order to underground storage of compressed air in aquifers and salt caverns, research have been carried out, but so far, studies have yet to be carried out regarding the storage of compressed air in depleted natural fractured oil reservoirs. This study simulated the storage of compressed air in a naturally fractured depleted oil reservoir, the effect of fracture on the rate of oxidation reactions, air dissolution and air diffusion in the oil and water phases. Also, for the first time, an examination of the fracture properties, including porosity, permeability, and fracture spacing on the amount of air recovery during CAES, was numerically simulated. Significantly Increasing the fracture porosity and permeability improves the air recovery and leads to a 19% and 16% respectively increase in the air recovery factor. In the fractured reservoir, increasing the fracture porosity has the most significant effect on reducing the air recovery factor and reducing the fracture spacing has the most negligible effect on the air recovery. Finally, the results of this study showed that due to the consumption and loss of air in the fractured reservoir compared to the conventional reservoir, the air recovery factor in the fractured reservoirs is less than the conventional reservoirs.

Fabrication of boron modified bi-functional air diffusion electrode for ciprofloxacin degradation: In-situ H2O2 generation and self-activation

In order to improve H2O2 in-situ generation in electrochemical system, a boron (B) modified air diffusion electrode (B@ADE) was fabricated in the present study. Carbon black (CB) doped by B was deposited on ADE surface as catalytic layer. Performance of B@ADE with different B/C mass ratios has been investigated and 0.3 was identified as the optimal one·H2O2 yield can be achieved 204.85 mg L-1 within 45 min at 0.3-B@ADE, which was 1.51 times for that of ADE. Meanwhile, H2O2 self-activation on B@ADE surface was observed and effects of different operating parameters on •OH formation have been analyzed. XPS analyzation demonstrated that BC2O, BC2O and C=O/O-C=O were related to H2O2 generation. DFT calculation revealed that BCO2 was benefit for O2 adsorption, while BC2O promoted *OOH desorption with lower free energy barriers for H2O2 and •OH generation. Quenching experiments for ciprofloxacin (CIP) demonstrated that •OH, O2•- and 1O2 were co-existed in the system with their contribution quantified. Four possible degradation pathways were proposed through active sites identification by DFT calculation and intermediates detection by HPLC-MS/MS. Bio-toxicity analyzation results showed that the toxicity of most intermediates was lowered than CIP. These results proved that electrochemical oxidation system with B@ADE enhanced in-situ H2O2 generation and self-activation, with great potential for practical application.

Horizontal Distribution of Liquid in an Over-Row Sprayer with a Secondary Air Blower

The aim of this study was to determine the influence of boom height above a crop stand and the spacing between nozzles and diffusers in an over-row sprayer on the uniformity of the horizontal spray distribution and the uniformity of the air velocity distribution. The experimental setup involved a prototype over-row sprayer equipped with a boom with a working width of 8 m and ten air diffusers with spray nozzles. Air diffusers were connected to one or two nozzles each, and they were installed on the boom at intervals of 60, 80, and 90 cm. Terminal airflow velocity at a canopy is determined by the height of a sprayer boom and the diffuser spacing, ranging from around 2 m s–1 to around 27 m s–1. The sprayer boom should be positioned at a height of 50 cm above a crop stand due to the difference between the minimum and maximum airflow velocities. The horizontal spray distribution was more uniform when the sprayer was equipped with hollow-cone nozzles instead of flat-fan nozzles; hollow-cone nozzles should be applied if the distance between nozzles needs to be adjusted to the row width and row spacing. The analyzed coefficients did not exceed 10% when the boom was positioned 50 cm above the crop stand and when the nozzles were spaced 80 cm apart, which suggests that, in this configuration, sprayers equipped with hollow-cone nozzles can also be applied to close-grown crops.

Enhancing Resistance to Wetting Transition through the Concave Structures.

Water-repellent superhydrophobic surfaces are ubiquitous in nature. The fundamental understanding of bio/bio-inspired structures facilitates practical applications surmounting metastable superhydrophobicity. Typically, the hierarchical structure and/or reentrant morphology have been employed hitherto to suppress the Cassie-Baxter to Wenzel transition (CWT). Herein, a new design concept is reported, an effect of concave structure, which is vital for the stable superhydrophobic surface. The thermodynamic and kinetic stabilities of the concave pillars are evaluated by continuous exposure to various hydrostatic pressures and sudden impacts of water droplets with various Weber numbers (We), comparing them to the standard superhydrophobic normal pillars. Specifically, the concave pillar exhibits reinforced impact resistance preventing CWT below a critical We of ≈27.6, which is ≈1.6 times higher than that of the normal pillar (≈17.0). Subsequently, the stability of underwater air film (plastron) is investigated at various hydrostatic pressures. The results show that convex air caps formed at the concave cavities generate downward Laplace pressure opposing the exerted hydrostatic pressure between the pillars, thus impeding the hydrostatic pressure-dependent underwater air diffusion. Hence, the effects of trapped air caps contributing to the stable Cassie-Baxter state can offer a pioneering strategy for the exploration and utilization of superhydrophobic surfaces.

Highly efficient electrosynthesis of hydrogen peroxide through reversible transformation between catechol and o-benzoquinone on polydopamine modified carbon black

Carbon-based materials are more promising catalysts for H2O2 electrochemical production. However, the common method for modifying carbon-based materials is surface functionalization with harsh and uncontrollable reaction conditions, hindering the precise regulation of the active sites. Herein, we proposed a carbon-based material modified by polydopamine (CB-PDA) that was easily prepared and used in air diffusion electrode system for H2O2 production. The rapid and reversible transformation between catechol and o-benzoquinone on PDA could improve the H2O2 selectivity from 75.5 % to 97.0 % during the electrocatalytic process. The detection of adsorbed *HOOH and *OOH in oxygen reduction reaction proved the preference of CB-PDA for the two-electron pathway. The H2O2 formation rate constant of CB-PDA increased significantly from 25.85 to 60.82 mM h−1. The highest cumulative H2O2 concentration could reach 10200 mg L−1 in 9 h. Long-term operation tests proved the good operational stability. Furthermore, this system was cost-effective without additional aeration energy consumption and could achieve rapid disinfection in 10 min, which would have great potential to be used in environmental remediation.

The potential of local exhaust combined with mixing and displacement ventilation systems to mitigate COVID-19 transmission risks

The performance of two types of air diffusers, a perforated duct and a low-velocity unit coupled with local exhausts, on airborne transmission and cross-infection was investigated in a meeting room. The effect of air diffusers’ locations on airborne transmission was investigated. Six local exhausts were installed above six workstations at 2.0 m height. Respiratory-generated airborne pathogens were simulated using SF6 in the exhaled air of the manikin acting as an infected person. The SF6 concentration in the inhaled air of five susceptible persons remained steady with perforated duct located on the ceiling and at 1.7 m height attached to the corridor wall, but fluctuated greatly when perforated duct were located on the floor, although with a much lower concentration level. The perforated duct under the warm window showed the best potential for mitigating airborne transmission. The concentration in the inhaled air was varied with horizontally supplied low-velocity unit, but much steadier with low-velocity unit at 1.7 m attached to the wall. With an adjusted airflow pattern from low-velocity unit, the inhaled concentration was much lower and uniform among the five susceptible persons. The contaminant removal effectiveness (CRE) was 4.3 with perforated duct under a warm window on the floor. With an adjusted airflow pattern from low-velocity unit, the CRE was much more consistent and increased from 2.1 to 3.9 with an airflow rate from 61 l/s to 116 l/s. The infection probability was the lowest with the perforated duct on the floor and adjusted low-velocity unit.

Investigation into the Computational Analysis of High–Speed Microjet Hydrogen–Air Diffusion Flames

High-speed microjet hydrogen–air diffusion flames are investigated computationally. The focus is on the prediction of the so-called bottleneck phenomenon. The latter has been previously observed as a specific feature of the present flame class and has not yet been investigated computationally. In the configuration under consideration, the nozzle diameter is 0.5 mm and six cases with mean nozzle injection velocities (U) between 306 m/s and 561 m/s are considered. The flow in the nozzle lance is analyzed separately to obtain detailed inlet boundary conditions for the flame calculations. It is confirmed by calculation that the phenomenon is mainly determined by the transition to turbulence in the initial parts of the free jet. The transitional turbulence proves to be the biggest challenge in predicting this class of flames, as the generally available turbulence and turbulent combustion models reach the limits of their validity in transitional flows. In a Reynolds-Averaged Numerical Simulation framework, the Shear Stress Transport model is found to perform better than alternative two-equation models and is used as the turbulence model. By neglecting the interactions between the turbulence and chemistry (no-model approach), it is possible to predict the morphology of the bottleneck flame and its dependence on U qualitatively. However, the position of the bottleneck is overpredicted for U < 561 m/s. The experimental flames in the considered U range are all attached to the nozzle. This is also predicted by the no-model approach. The Eddy Dissipation Concept (EDC) used as the turbulence combustion model predicts, however, lifted flames (with increasing lift-off height as U decreases). With the EDC, no bottleneck morphology is observed for U = 561 m/s. For lower U, the EDC results for the bottleneck position are generally closer to the measurements. It is demonstrated that accuracy in predicting the bottleneck position can be improved by ad hoc modifications of the turbulent viscosity.

Enhancing energy and nitrogen removal efficiency through automatic split injection and innovative aeration device: A study of low C/N ratio environments

A new aeration device based on Bernoulli's principle, Jetventrumixer (JVM), was introduced into an aeration tank in denitrification process, which involved an automatic split injection system (ASIS) into two denitrification tanks every 10 minutes. Real-time monitoring of influent water allowed the calculation of the C/N ratio, enhancing the utilization efficiency of internal carbon sources while reducing the need for external carbon. The comparison of the JVM with the conventional air diffuser for 100 days operation showed that the removal efficiency for NH4+-N in both systems was approximately 98 %, but the nitrification efficiencies were 84 % and 80 %, respectively. This indicates that the JVM achieves an high enough removal efficiency and nitrification efficiency compared with conventional air diffuser system with dramatic reduction in energy consumption by 52.1 %. When the influent wastewater was split and injected into duplicate denitrification tanks at ratios of 3:7, 5:5, and 7:3, the total nitrogen (TN) removal efficiencies were 77 %, 73 %, and 72 %, respectively. In contrast, with the implementation of the ASIS, the TN removal efficiency increased up to 82 %. The increase in TN removal indicates that real-time monitoring could stably track changes chemical composition in wastewater influent over 24 h and introducing ASIS facilitate the efficient utilization of internal carbon sources, thereby enhancing denitrification efficiency and improving TN removal efficiency. Finally, the greenhouse gas (GHG) emissions from the JVM and air diffuser were 9.39401 and 19.60488 tCO2eq year-1, respectively, representing a 52% reduction. Therefore, JVM and ASIS successfully reduced energy consumption and enhanced both nitrification and denitrification efficiencies.

A concept for non-uniform thermal irradiation emulation in an immersive virtual environment

This study addresses the challenge of emulating human thermal environments without the need to build physical mock-ups. The aim is to complement the established technology of emulating visual environments with head-mounted displays. For the user, the virtual environment (VE) emulates an arbitrary indoor environment including visual and thermal aspects. In contrast to conventional climate chambers, we describe a concept to emulate arbitrary non-uniform environments and room geometries without the need to construct or modify separate physical mock-ups for each scenario being tested. By fully emulating air temperatures as well as the thermal irradiation, a user can experience the same thermal sensation as in the actual environment. An air conditioning system and nine supply air diffusers are used for the air temperature and humidity control. For thermal radiation, 45 temperature-controlled surfaces are arranged in a hemicube around the user. An arbitrary environment’s thermal irradiation is emulated by a projection of temperatures on the hemicube surface elements. This study compares two methods for setting the surface temperatures in the VE to emulate thermal irradiation. Finally, it presents the results of computational fluid dynamic simulations that benchmark the capability of the VE to emulate a non-uniform indoor thermal environment. For the non-uniform thermal environment benchmark scenario, the assumption of a uniform enclosure (using the surface average radiant temperature) resulted in a surface root mean square error of 2.2 K (local deviation of up to 4.6 K) of radiant temperature on the person dummy surface. The projection method was implemented for the VE, utilising temperature-controlled surfaces. Depending on the projection method used to determine the surface temperatures, it was possible to decrease the root mean square error of the radiant temperature in the emulated environment to a range of 0.4 K to 0.7 K.

FUNDAMENTAL APPROACH TO PREDICT TIRE AIR PRESSURE LOSS OVER TIME

ABSTRACT Rubber material used in consumer products is vulcanized to improve its strength, viscoelasticity, and long and short-term durability. During the cure process, the morphology of the material evolves to form a highly crosslinked chain network, leading to a product that is less porous and less susceptible to air diffusivity. However, the formulation of the rubber compounds always create micropores or voids within them. Several laboratory tests are used to measure the material’s ability to resist the flow of air through it and to assess its porosity, especially under pressure. Residual-based integrated surface flux calculations are used to determine the evolution of air pressure as a function of time in an enclosed volume such as the cavity of an inflated tire. A finite element formulation was established for complex applications such as tires to predict the intracarcass pressure distribution. The capability of this simulation methodology was demonstrated for a tire with different inner liner compositions.

Mitigating thermal stratification in lakes/reservoirs through wind-powered air diffusers.

Thermal stratification can cause various water quality issues in large water bodies. To address this, a new wind-powered artificial mixing system is designed and experimentally tested for various Savonius rotor combinations (three-stage and four-stage rotors). These turbines directly utilize wind energy to draw air into the water column for aeration, bypassing the need for electrical conversion. The rotor performances were tested in terms of power and torque coefficients. Additionally, these rotors were tested for artificial mixing efficiencies in a specially designed water tank that can mimic thermal stratification typically observed in an actual water supply reservoir. Among the rotors, the three-stage rotor with a 60° phase shift was found to exhibit superior power and torque coefficients, achieving a power efficiency value of 0.14. As for the mixing efficiency, the four-stage rotor with a 45° phase shift excelled in mixing efficiency, reaching 95%. PRACTITIONER POINTS: A new wind-powered artificial mixing system is designed and tested for various Savonius rotor combinations. While keeping the total rotor height constant, the three-stage Savonius rotor class shows superior performance against the four-stage Savonius rotor class in terms of power and torque efficiency. Apart from the rotor performance results, the four-stage Savonius rotors show greater artificial mixing efficiency than the three-stage Savonius rotors. Single-pump/diffuser artificial destratification system exhibits better mixing efficiency than multiple-pump/diffuser systems.

Effect of biomass concentration in membrane bioreactor design on alpha factor for two large pilot systems: Case study of mechanical surface aeration and air insufflation system

In the literature, the studies on wastewater treatment process have shown a great interest in aeration system, most of them were performed on small pilot lab-scale. However, it still an important need to provide useful information aiming at reducing the operating costs and providing decision support to choose aeration devices. Considering that membrane bioreactors operating with high biomass concentrations up to 20–30 g of suspended solids (SS) per liter, the present study was carried out on a larger pilot lab-scale ( ± 500 l) of insufflation system and mechanical surface aeration on the same fresh sludge with concentration varying between 4.6 and 19.8 g/l. The comparison with literature data shows good correspondence with values obtained with our insufflation system but a great difference from values obtained in a mechanical system. In addition, this research provides a better insight on the calculation method that can be used to estimate the critical parameters of the oxygen transfer, and analyses the feasibility of air diffusion substitution by surface aeration system of Louvain La Neuve wastewater treatment plant of 13000 population equivalent. This extrapolation proved that a saving of ± 50,000 € per year can be achieved by choosing surface aeration rather than aeration by air insufflation.

Spatial Temperature Measurements in a Swirl-Stabilized Hydrogen–Air Diffusion Flame at Elevated Pressure Using Laser-Induced Grating Spectroscopy

Spatial Temperature Measurements in a Swirl-Stabilized Hydrogen–Air Diffusion Flame at Elevated Pressure Using Laser-Induced Grating Spectroscopy

Pengaruh Store Atmosphere terhadap Revisit Intention Konsumen di Deja Coffee & Pastry Kelapa Gading

Factors that influence someone to visit a café are not only influenced by taste but also pay attention to the store atmosphere, where consumers can feel comfortable in the café. Deja Coffee & Pastry is a business operating in the food & beverages sector which is located in Kelapa Gading. The issue experienced by Deja Espresso and Baked good is that there are numerous purchaser protests in regards to comfort connected with the store environment and the store air itself can impact the event of return to expectation in light of the customer's insight during their visit. The motivation behind this examination is to figure out how the store air impacts return to aim at Deja Espresso and Baked good Kelapa Gading connected with the issues experienced. This examination utilizes an elucidating sort of quantitative exploration. The populace in this study are buyers who have visited Deja Espresso and Baked good Kelapa Gading without removing. The inspecting procedure utilized purposive examining of 100 individuals. The information investigation procedure utilized is instrument trying which incorporates legitimacy testing and unwavering quality testing, then, at that point, old style presumption testing, speculation testing, then coefficient of assurance, The examination results show that there is a synchronous impact applied by the store environment on return to aim at Deja Espresso and Baked good Kelapa Gading, yet to some degree the inside show aspects don't impact return to aim. Ideas for Deja Espresso and Cake Kelapa Gading are to add an air diffuser to eliminate terrible fragrances, fix the hindrance between the smoking region and the non-smoking region which upsets the solace of guests.

Strategic ventilation design for reducing airborne infection transmission in a two-story building: A numerical approach

This study employs Computational Fluid Dynamics (CFD) to assess the impact of various ventilation configurations on respiratory droplet dispersion in a two-story restaurant building, aiming to reduce airborne infection transmission. A total of 24 scenarios, involving three ventilation configurations and eight individuals as potential droplet sources, are studied. The configurations—Case A, Case B, and Case C—are analyzed for their effectiveness in controlling droplet dispersion and improving air exchange effectiveness (AEE). Case B, with an outlet near occupants and an inlet above the zone separation, proved most effective in minimizing the droplet transmission between floors, reducing suspended airborne droplets on each floor, and preventing surface contamination, thereby enhancing indoor air quality. Despite the positioning inlet and outlet vents near crowded areas, Case A falls short in effectively removing droplets due to the intricate airflow patterns caused by air diffusers. Case C showed larger AEE but was less effective in droplet dispersion control, indicating a crucial balance between optimizing air circulation and limiting pathogen dispersion is needed. The findings underscore the importance of strategic ventilation design in mitigating airborne infection transmission in multi-level buildings. An optimal configuration, as demonstrated by Case B, combines efficient air distribution with strategic placement of ventilation components to create barriers against interzonal droplet transmission. This study highlights the potential of targeted ventilation strategies to significantly reduce the risk of airborne infection in enclosed, populated spaces.

Sustainable H2O2 production in a floating dual-cathode electro-Fenton system for efficient decontamination of organic pollutants

Electrochemical advanced oxidation processes (EAOPs) based on natural air diffusion electrode (NADE) promise efficient and affordable advanced oxidation water purification, but the sustainable operation of such reaction systems remains challenging due to severe cathode electrowetting. Herein, a novel floating cathode (FC) composed of a stable hydrophobic three-phase interface was established by designing a flexible catalytic layer of FC. This innovative electrode configuration could effectively prolong the service life of the cathode by mitigating the interference of H2 bubbles from the hydrogen evolution reaction (HER), and the H2O2 production rate reached 37.59 mg h−1·cm−2 and realize a long-term stable operation for 10 h. Additionally, an FC/carbon felt (CF) dual-cathode electro-Fenton system was constructed for in situ sulfamethoxazole (SMX) degradation. Efficient H2O2 production on FC and Fe(III) reduction on CF were synchronously achieved, attaining excellent degradation efficiency for both SMX (ca. 100%) with 2.5 mg L−1 of Fe(Ⅱ) injection. For real wastewater, the COD removal of the FC/CF dual-cathode electro-Fenton system was stabilized at exceeding 75%. The practical application potential of the FC/CF dual-cathode electro-Fenton system was also demonstrated for the treatment of actual landfill leachate in continuous flow mode. This work provides a valuable path for constructing a sustainable dual-cathode electro-Fenton system for actual wastewater treatment.

Innovative High-Induction Air Diffuser for Enhanced Air Mixing in Vehicles and Personalized Ventilation Applications

Innovative High-Induction Air Diffuser for Enhanced Air Mixing in Vehicles and Personalized Ventilation Applications

Efficient H2O2 Production and Activation by Air Diffusion Cathode Combined with Ultraviolet for Lake Water Treatment: A Long-Term Evaluation

This study utilizes a natural air diffusion cathode (ADC) and an ultraviolet lamp to construct a UV/H2O2 reactor for the in situ synthesis and activation of H2O2 and evaluates its potential application in practical lake water treatment. The results indicate that the reactor exhibits stable treatment performance during a continuous flow experiment of 80 h. The air diffusion cathode maintains an H2O2 concentration of above 350 mg·L−1 in sodium sulfate electrolyte and shows no decreasing trend. Under the condition of approximately 59% H2O2 utilization, the removal rates of COD and TOC are 37.6% and 40.0%, respectively; the rate of reduction of A254 is 64.3%; while the total bacterial count removal rate reaches 100%. Large organic molecules in surface water are degraded to small organic molecules and mineralized to inorganic minor molecules. It effectively ameliorates the problem of organic pollution of surface water and effectively kills bacteria and improves the microbiological safety of the water body. Therefore, the UV/H2O2 system developed in this study, based on electrochemically produced H2O2, is an effective method for treating micro-polluted surface water.

Self aeration and energy dissipation on a steep stepped chute: how does physical modelling compare to prototype observations?

For the last five decades, a number of overflow stepped chutes were built because the staircase shape is conducive to reduced construction costs and increased rate of energy dissipation. The stepped chute operations are characterised by air‐water flows that are highly turbulent flows with a large rate of energy dissipation, in comparison to smooth chutes. Herein, physical measurements were performed in a large‐size 1 V: 0.80H stepped chute model, with a steep slope typical of modern concrete gravity dams. The results are compared to visual observations of prototype spillway operation under Froude similar conditions. The detailed two‐phase flow measurements were conducted to characterise finely the self‐aeration and air diffusion process downstream of the inception region of free‐surface aeration. The bubble count rate profiles scaled with the instantaneous void fraction variance, and the relationship was biased close to the stepped invert under the influence of large‐scale vortical structures. The rate of energy dissipation was carefully estimated based upon the two‐phase flow measurements and the results are compared to earlier results on similar steep invert slopes and prototype data estimates. At the downstream end of the stepped chute, the rate of energy dissipation ranged from 43 to 46%, i.e. more than twice that on a smooth-invert chute for a similar chute length and discharge range.Graphical abstractCharacteristics of self-aerated stepped chute flows for dc/h = 1.3—(I) Prototype flow at Hinze Dam (Re = 4.0 × 107); (II) Air-water flow properties in the large-size laboratory model (1:15) stepped spillway (Re = 6.1 × 105)

Hierarchical Fe-Bi/Bi7O9I3/OVs microspheres coupled with natural air diffusion electrode to achieve efficient heterogeneous visible-light-driven photoelectro-Fenton degradation of tetracycline without aeration

Hierarchical Fe-Bi/Bi7O9I3/OVs microspheres coupled with natural air diffusion electrode to achieve efficient heterogeneous visible-light-driven photoelectro-Fenton degradation of tetracycline without aeration