Search

• A novel side-aerated reactor for in-situ H 2 O 2 electrosynthesis was designed. • Side-aerated reactor coupled with a composite cathode greatly improved H 2 O 2 production. • Different aeration system and cathodes were evaluated for comparison. • Key factors for in-situ H 2 O 2 electrosynthesis were determined. The active graphite felt (GF) catalytic layer was effectively synthesized through a wet ultrasonic impregnation-calcination method, modified with CB and PTFE, and implemented in a pioneering side-aeration electrochemical in-situ H 2 O 2 reactor. The optimal mass ratio (CB: PTFE 1:4) for the modified cathode catalytic layer was determined using a single-factor method. Operating under optimum conditions of initial pH 5, 0.5 L/min air flow, and a current density of 9 mA/cm2, the system achieved a remarkable maximum H 2 O 2 accumulation of 560 mg/L, with the H 2 O 2 production capacity consistently exceeding 95 % over 6 usage cycles. The refined mesoporous structure and improved three-phase interface notably amplified oxygen transfer, utilization, and H 2 O 2 yield. Side aeration led to an oxygen concentration near the cathode reaching 20 mg/L, representing a five-fold increase compared to the 3.95 mg/L achieved with conventional bottom aeration. In the final application, the reaction system exhibited efficacy in the degradation of landfill leachate concentrate. After a 60-minute reaction, complete removal of chroma was attained, and the TOC degradation rate surpassed 60 %, marking a sixfold improvement over the conventional system. These results underscore the substantial potential of the system in H 2 O 2 synthesis and environmental remediation. [ABSTRACT FROM AUTHOR]

A number of bolt-microtubular anode supports (BMASs) are manufactured by winding the corresponding thin tapes on threaded rods of different thread pitches and depths, followed by co-lamination using isostatic press. Bolt-microtubular cells (BMCs) are also constructed on BMASs to investigate the effects of the created surface patterns on the cell performance and microstructure. The bolt-microtubular cell, whose anode support is patterned by using a threaded rod with 0.8 mm thread pitch and 0.4 mm thread depth, exhibits ∼92% higher maximum performance than that of the reference cell at 800 ºC under 0.3 NL/min hydrogen flow and stagnant air. The almost doubled performance is mainly due to the increase in anode-electrolyte and cathode-electrolyte interfacial areas by the surface patterns created. The cell is also subjected to a 200-h life test at 800 °C and 0.7 V and demonstrates a stable performance. [ABSTRACT FROM AUTHOR]

An experimental study to investigate the flow of liquid jet issued from a high aspect ratio nozzle slit into an incoming airflow by changing the orientation angle from the incoming free-stream was performed. A two-dimensional liquid sheet emerged from the narrow slit into the subsonic air crossflow. Different orientation angles between 0 and 90 degrees were studied. High-speed photography and shadowgraphy techniques were utilized to visualize the flow physics. The influence of the slit orientation angle on the flow morphology and the flow regimes of liquid sheets was investigated. Some fluid flow parameters were obtained by analyzing the images. The changes in breakup height of different orientations were measured. A model was offered for the breakup height of the liquid sheet based on the liquid-to-gas momentum ratio, gas Weber number, and a new non-dimensional parameter as a representation of the angle of slit orientation. Also, the defined sheet trajectory for each orientation angle was obtained, and the variations were examined. Empirical correlations for the defined trajectory of the sheet in terms of liquid to gas momentum ratio and gas Weber number for each orientation angle were proposed. [ABSTRACT FROM AUTHOR]

Respiratory–swallowing coordination (RSC) is well established as an essential airway‐protective mechanism. Previous studies have used nasal airflow and/or kinematic rib cage and abdominal measures to assess respiration surrounding swallowing, meaning that the direct influence of oral respiration on RSC remains unknown. This study used a partitioned oronasal facemask to compare respiratory phase patterns measured using isolated nasal airflow with those measured using combined oronasal airflow during non‐ingestive and ingestive swallowing tasks. Twenty‐four healthy individuals with no respiratory or swallowing disorders were assessed at rest and during cued dry, 10 mL water, continuous drinking and cracker swallowing tasks. Respiratory phase patterns were determined for discrete swallows using the nasal and combined oronasal channels separately. There was variable agreement between respiratory phase patterns according to the nasal and oronasal channels across swallowing conditions. The frequency of exhale–swallow–exhale, inhale–swallow–exhale and exhale–swallow–inhale patterns increased by 2%–3% each with the addition of oral flow data to nasal data, whereas the prevalence of inhale–swallow–inhale and ambiguous patterns decreased. This suggests that estimates of respiratory phase patterns are altered minimally by inclusion of oral respiratory estimates in a healthy sample. There were several additional findings of note, including lower within‐participant, within‐session trial consistency (test–retest reliability) than expected, suggesting high variability in respiratory phase patterns across trials. Additionally, data showed evidence of swallowing non‐respiratory flow at the beginning and end of the respiratory–swallowing pause, moving in both inward and outward directions, potentially expanding current understanding of swallowing non‐respiratory flow. Further in‐depth physiological investigations are required to improve understanding of these findings. [ABSTRACT FROM AUTHOR]

Abstract\nNOVELTY STATEMENTFloating treatment wetlands (FTWs) are natural solutions for purifying polluted water, providing a green surface area and improving city landscape. This study investigated if the efficiency of FTWs can be improved by aeration for treating contaminated canal water. The three used plant species were Canna generalis, Phragmites australis, and Cyperus alternifolius. The experiment was carried out in three FTWs with aeration and three without aeration to compare the removal for COD, NH4+-N, E. coli, PO43−-P, and Fe. In the aerated FTWs, air blowers were installed to run at two different air flow rates of 2.5 L min−1 (Batch 1) and 1.0 L min−1 (Batch 2). Aeration increased the dissolved oxygen concentrations in each tank, which came over 6.5 mg L−1 in both batches. This study sheds light on the positive impact of aeration has on COD and NH4+-N removal: these are nearly three-fold higher compared to non-aeration conditions and reached approximately 99% (1.7-log reduction) for E. coli removal. Additionally, the plant growth rate in the aerated FTWs was higher than in the non-aerated ones. The average shoot growth rate of Phragmites australis was 0.76 cm d−1 for the aerated FTW which was two-fold higher compared to the non-aerated one.This article investigates the treatment performance of Floating Treatment Wetlands (FTWs) coupled with aeration to reduce the diffuse pollution in canal water. The results showed that the aeration enhanced the treatment of organics and nutrients, and the plant growth of the aerated FTWs was two-fold higher than that of non-aerated FTWs, which has a phytoremediation potential for treating canal water in Ho Chi Minh city [ABSTRACT FROM AUTHOR]

ABSTRACT Background Objective Methods Results Conclusion The role of objective nasal airflow measures using peak nasal inspiratory flow (PNIF) and rhinospirometry in supporting clinical examination findings when offering patients septoplasty remain undefined.To explore the baseline relationships between clinical examination findings, subjective reported symptoms and objective nasal patency measures in nasal obstruction.This is a sub‐study of the NAIROS trial. Participants with nasal obstruction secondary to septal deviation were included in this NAIROS sub‐study. The side of septal deviation, enlargement of inferior turbinate (IT), the need for IT reduction if septoplasty was being performed, the area of septum deflecting into the airway and observer rated airway block (ORAB–arbitrarily divided by <50% and >50% blockage) were assessed by clinicians. The subjective score of nasal obstruction was assessed using the Double Ordinal Assessed Subjective Scale (DOASS). Objective nasal patency measures (e.g., nasal partitioning ratio, [NPR] and PNIF) were measured using PNIF and rhinospirometry.The mean NPR for left‐sided, both‐sided and right‐sided septal deviation was −0.35, −0.02 and 0.51, respectively (p < 0.001). There was very weak correlation between the requirement for IT reduction and PNIF change (0.13, p < 0.01). There was no difference in mean PNIF (94 L/min vs. 93 L/min) and mean DOASS (0.33 vs. 0.38) for participants with ORAB rated <50% and >50%. The mean NPR for participants with ORAB >50% was higher than for those with ORAB <50% (0.51 vs. 0.41, p = 0.002). There was strong correlation between the DOASS and NPR (+0.737, p < 0.001). The mean DOASS score for right‐sided, both‐sided and left‐sided septal deviation was 0.32, 0.05 and −0.29, respectively (p < 0.001).This study identified strong relationships between the clinician rated side of septal deflection, the patient reported DOASS and the objective NPR measurements. NPR and the clinician rated degree of airway blockage were concordant. [ABSTRACT FROM AUTHOR]

Highlights Environmental hazards caused by the ever‐increasing end‐of‐life (EoL) glass fiber reinforced polymer (GFRPs) composite waste is of major concern for the sustainable development of the industry. Compared to land filling or incineration, pyrolysis is one of the most promising environmentally friendly methods of disposal of EoL GFRPs. Pyrolysis not only results in recovery of clean glass fibers but other valuable products, such as oils. However, long processing time at elevated temperature leads to aggravation of already existed surface flaws along with the structural changes. Therefore, thermal conditioning of glass fibers results in severe deterioration of the strength in recovered fibers and hence limiting the use of recovered fibers to low end‐products. In this study, a new strategy was adopted where instead of complete cleaning of the fibers at pyrolysis stage, the fibers were partially oxidized and the complete removal of char from the surface of glass was done during hot alkaline etching. This strategy was opted to enhance the quality of the required fibers while reducing the processing time. The results showed ~200% increase in strength of fibers after the combined treatment of pyrolysis and post etching compared to the just pyrolyzed samples with etching time of just 1 min. End‐of‐life panels of GFRPs were pyrolyzed under inert environment of Argon. Residual char was partially removed through post oxidation under flowing air. Hot alkaline etching resulted in complete removal of char and surface defects. Partial oxidation and short etching cycles resulted in improved strength of recovered glass fibers. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) are employed in a range of devices due to their high energy and power density. However, the increased power density of LIBs raises concerns regarding their safety when subjected to external abuse. The thermal behavior is influenced by a number of factors, i.e., the state of charge (SoC), the cell chemistry and the abuse conditions. In this study, three distinct cylindrical Li-ion cells, i.e., lithium nickel cobalt aluminum oxide (NCA), lithium titanate oxide (LTO), and lithium iron phosphate (LFP), were subjected to thermal abuse (heating rate of 5 °C/min) in an air flow reactor, with 100% SoC. Venting and thermal runaway (TR) were recorded in terms of temperature and pressure, while the emitted products (gas, solid, and liquid) were subjected to analysis by FT-IR and ICP-OES. The concentrations of the toxic gases (HF, CO) are significantly in excess of the Immediate Danger to Life or Health Limit (IDLH). Furthermore, it is observed that the solid particles are the result of electrode degradation (metallic nature), whereas the liquid aerosol is derived from the electrolyte solvent. It is therefore evident that in the event of a LIB fire, in order to enhance the safety of the emergency responders, it is necessary to use appropriate personal protective equipment (PPE) in order to minimize exposure to toxic substances, i.e., particles and aerosol. [ABSTRACT FROM AUTHOR]

Clinical trials of hypothermia after pediatric cardiac arrest (CA) have not seen robust improvement in functional outcome, possibly because of the long delay in achieving target temperature. Previous work in infant piglets showed that high nasal airflow, which induces evaporative cooling in the nasal mucosa, reduced regional brain temperature uniformly in half the time needed to reduce body temperature. Here, we evaluated whether initiation of hypothermia with high transnasal airflow provides neuroprotection without adverse effects in the setting of asphyxic CA. Anesthetized piglets underwent sham-operated procedures (n = 7) or asphyxic CA with normothermic recovery (38.5°C; n = 9) or hypothermia initiated by surface cooling at 10 (n = 8) or 120 (n = 7) min or transnasal cooling initiated at 10 (n = 7) or 120 (n = 7) min after resuscitation. Hypothermia was sustained at 34°C with surface cooling until 20 h followed by 6 h of rewarming. At 4 days of recovery, significant neuronal loss occurred in putamen and sensorimotor cortex. Transnasal cooling initiated at 10 min significantly rescued the number of viable neurons in putamen, whereas levels in putamen in other hypothermic groups remained less than sham levels. In sensorimotor cortex, neuronal viability in the four hypothermic groups was not significantly different from the sham group. These results demonstrate that early initiation of high transnasal airflow in a pediatric CA model is effective in protecting vulnerable brain regions. Because of its simplicity, portability, and low cost, transnasal cooling potentially could be deployed in the field or emergency room for early initiation of brain cooling after pediatric CA. NEW & NOTEWORTHY: The onset of therapeutic hypothermia after cardiac resuscitation is often delayed, leading to incomplete neuroprotection. In an infant swine model of asphyxic cardiac arrest, initiation of high transnasal airflow to maximize nasal evaporative cooling produced hypothermia sufficient to provide neuroprotection that was not inferior to body surface cooling. Because of its simplicity and portability, this technique may be of use in the field or emergency room for rapid brain cooling in pediatric cardiac arrest victims. [ABSTRACT FROM AUTHOR]

Bats rely on their hand-wings to execute agile flight maneuvers, to grasp objects, and cradle young. Embedded in the dorsal and ventral membranes of bat wings are microscopic hairs. Past research findings implicate dorsal wing hairs in airflow sensing for flight control, but the function of ventral wing hairs has not been previously investigated. Here, we test the hypothesis that ventral wing hairs carry mechanosensory signals for flight control, prey capture, and handling. To test this hypothesis, we used synchronized high-speed stereo video and audio recordings to quantify flight and echolocation behaviors of big brown bats (Eptesicus fuscus) engaged in an aerial insect capture task. We analyzed prey-capture strategy and performance, along with flight kinematics, before and after depilation of microscopic hairs from the bat's ventral wing and tail membranes. We found that ventral wing hair depilation significantly impaired the bat's prey-capture performance. Interestingly, ventral wing hair depilation also produced increases in the bat's flight speed, an effect previously attributed exclusively to airflow sensing along the dorsal wing surface. These findings demonstrate that microscopic hairs embedded in the ventral wing and tail membranes of insectivorous bats provide mechanosensory feedback for prey handling and flight control. [ABSTRACT FROM AUTHOR]

A novel plasma reactor is being investigated for green NOx production, crucial for nitrate‐based fertilizer manufacturing. Various parameters, including air flow rates, gas ratios, ozone, and catalyst effects are explored for NO → NO2 conversion. NOx concentrations reach ~0.6 vol%, with a total production of ~9.7 gr/h and energy cost of ~3.0 mJ/mol, notably favorable for atmospheric gliding arc plasma. Selectivity (~75%) towards NO2 is achieved with ozone addition or catalytic treatment, pivotal for nitrate fertilizer and HNO3 production. [ABSTRACT FROM AUTHOR]

A numerical investigation for a solar air heater integrated with a multi-section solar distiller has been conducted with a novel design of solar distiller with interior sections. A mathematical description of the solar distiller is made and solved with a MATLAB code. The air flow in the solar air heater, the water height in the solar distiller, and the number of interior sections have all been studied. To validate the numerical system, an experimental system was built. The theoretical model and the experiment performed appear to be in satisfactory correlation. The best working conditions occur when the system is run with a lower air flow rate, a lower saline water height, and a greater number of interior sections with productivity reaching 1242.6 ml/m2 per day, a gain output ratio (GOR) about 0.622 and air heater efficiency about 35%. In the normal case of output salinity between 0 and 500 ppm, the cost was reduced by 96.7%, and by 96.3% in the case of four interior sections. Water cost reduction is also observable at the same output salinity, with 54.1% at 0 ppm and 62.4% at 200 ppm between number of interior sections = 0 and 4. [ABSTRACT FROM AUTHOR]

• Numerical modeling of an integrated refrigerated container. • Different cargo pallet arrangements and cargo packaging boxes are tested. • Airflow short-circuiting has both positive and negative effects on cargo cooling. • Improving vertical airflow in cargo pallets enhances cargo cooling than air gaps. Improving the performance of a refrigerated container is crucial in effectively preserving thermal-sensitive cargo. The combined effect of vertical airflow resistance and airflow short-circuiting in air gaps play a vital role in cargo cooling. This study numerically investigates the effects of cargo vertical airflow resistance and air gaps between cargo pallets using two commonly used apple packaging boxes, each stacked in six different cargo pallet arrangements. A heat transfer enhanced refrigerated container design and a numerical model developed from the present authors' previous studies are used. The numerical model uses the porous medium model to incorporate the refrigeration unit and cargo within the refrigerated container. Additionally, the numerical domain includes the T-bar floor in the refrigerated container. Initially, the airflow characteristics based on vertical airflow resistance and air gaps are discussed. Then, the corresponding effects on cargo cooling are addressed. Results show that the air gaps between the cargo pallets have positive and negative effects on cargo cooling. In cargos with lower vertical airflow resistance, an increase in air gaps leads to reduced cargo cooling and elevated temperature non-uniformity. Conversely, cargos with higher vertical airflow resistance experience increased cooling rates and reduced temperature non-uniformity with the increase in air gaps. However, avoiding airflow short-circuiting through the air gaps between the cargo pallets and improving the vertical airflow inside the cargo pallets can provide better cargo cooling, which outweighs the positive cooling effect of the air gap. [ABSTRACT FROM AUTHOR]

Coal is an essential primary energy for the national economy and people's livelihood. In recent years, with the rapid growth of the consumption of high-quality coal resources, Lignite with a low degree of metamorphism has been extensively exploited and utilized. In this paper, desulfurization and ash reduction treatment of 6–0 mm fine-grade low-grade high-sulfur Lignite was carried out using a FGX dry separation bed (FGX FGX compound dry separation bed). The migration and distribution of differentiated density particles in the bed under the action of cascade air flow were mainly studied, and the influence of vibration intensity (amplitude and frequency) on the separation effect of fine-grade low-grade high-sulfur Lignite was explored. At the same time, the material distribution characteristics of each section in the direction of the discharge edge of the bed were systematically analyzed, the material distribution area of the bed was determined, the optimal operating parameters (A = 2.8 mm, f = 26 Hz, V = 2.29 m/s) were obtained, and the sorting test was carried out under the optimal parameter conditions. The test results show that when the vibration frequency f = 26 Hz, the sulfur segregation degree of bedding materials reaches the maximum Ss = 0.36, and the sulfur content of materials in I, II, and III regions is 0.85%, 5.47%, and 18.78%, respectively. The stratification effect of bedding materials is the best. When A = 2.8 mm, the material sulfur segregation reaches the minimum value of Ss = 0.28, and the average sulfur content of materials in I, II, and III regions is 0.78%, 5.46% and 18.27%, the material is stratified according to density. When the airflow rate is 2.55 m/s. The stratification effect of bed material is best according to density. The clean coal yield is 69.87%, and the sulfur content is 0.98%. The gangue yield is 30.13%, and the sulfur content is 18.66%. The Ep value of energy deviation is 0.11 g/cm3, which realizes high precision dry desulfurization and upgrading fine-grade, low-grade, and high sulfur lignite. [ABSTRACT FROM AUTHOR]

To reveal the evolution characteristics and driving factors of net primary productivity (NPP) of vegetation in arid regions, with Kashi region as a representative case, this study utilized various remote sensing satellite data, including MOD13A1/Q1, MOD09A1, and MOD17A3, to estimate vegetation NPP in the study area from 2001 to 2020 using the CASA model. The study aimed to express the impact of external driving factors on vegetation NPP from the perspectives of climate change and land use change. The results indicated: (1) Over the past two decades, the overall trend of vegetation NPP in the study area exhibited an initial increase, followed by a subsequent decrease. Specifically, from 2001 to 2015, vegetation NPP increased at a rate of 0.303, while from 2016 to 2020, it decreased at a rate of -0.202. (2) Through trend analysis and significance testing using the Sen+MK method, it was found that 37% of the study area showed a significant increasing trend in NPP, while 73% exhibited a decreasing trend. (3) Precipitation in the Kashi region had a stronger correlation with NPP than temperature. In the southwest region, the Pamir Plateau and Karakoram Mountains showed positive correlations with both temperature and precipitation, with warm and moist airflows promoting NPP in high latitudes. (4) )During the period of 2001-2020, Grassland in the study area degraded at the fastest rate, with a change rate of -2.1%, and the largest increase was observed in farmland, with a change rate of 2.7%; the vegetation NPP decreased by a total of 2748.3 TgC, and the study area shows a decreasing trend in the value of vegetation NPP in the future period. [ABSTRACT FROM AUTHOR]

The application of turbulators to improve thermal performance and thermal enhancement in heat exchangers because of the significance of energy management and optimization is one of the interesting topics for researchers. Analysis of aerodynamic turbulator in internal flow has been less discussed in previous studies. Therefore, the present work focuses on the effect of a perforated sphere turbulator in a circular pipe with square, circular, oval, and hexagonal geometry holes on turbulent flow characteristics and thermal performance. These turbulators are placed with equal obstruction against the flow of air passing inside the pipe at Re = 6000–24000 in wall conditions of constant heat flux. Ansys Fluent software is used for numerical solutions, and the results are validated with an experimental paper. According to the results, the hexagonal geometry creates less pressure drop than other geometries. The thermal performance in the pipe with innovative aerodynamic turbulators is improved compared to the smooth pipe and the pipe equipped with conventional turbulators. The highest thermal performance of 1.256 is obtained for the turbulator with an oval hole. Also, the range of Nusselt number compared to the plain pipe for turbulator with circular, hexagonal, square, and oval holes increases by 1.97–2.46, 2.24–2.65, 1.58–1.89, and 2.48–2.81 times, respectively. The effect of the proposed new turbulators was compared with previous studies in this field, and the results are promising. [ABSTRACT FROM AUTHOR]

In recent years, the rehabilitation of spillways and design of new dam constructions have considered the combination of a stepped chute with a labyrinth weir crest, highlighting the need for hydraulic information for this specific spillway type. To address currently missing design guidance, a novel study was conducted on a 10.7° round-crested labyrinth weir with a 3H:1V sloped chute with multiple step heights. The results include guidance for estimating flow depths along the chute and selecting a chute wall height; the role of the labyrinth weir on aeration, streamwise and transverse flow uniformity, and general flow patterns; and energy dissipation by the labyrinth crest and by individual steps. It was found that stepped chutes with a labyrinth crest are aerated from the impact of the nappes in the labyrinth outlet cycles, which continued to the chute entrance where the maximum air concentrations and flow depths occurred. The labyrinth crest also generates nonuniform flow patterns and air-water flow properties that have a significant effect on energy dissipation as the nonuniformity and potential drag reduction (due to the stronger aeration) results in less energy dissipated compared with published literature of stepped spillways with linear crests. The present findings provide first guidance for practitioners to combine labyrinth weirs with stepped chutes. [ABSTRACT FROM AUTHOR]

[Display omitted] • We proposed an SPA based on a Kresling-like pattern with a rigid skeleton by observing the cloning and moving behaviors from salps. • An extensible inserting structure is innovatively designed to replace the creases in traditional Kresling patterns. • The SPA can perform an axial contraction motion without twisting and a controllable bending motion. • The number of layers of Kresling-like patterns is changeable by adding or reducing skeleton components. • The elongation can reach to above 162% and the output force can reach to above 6.36 N. Biomimetic soft pneumatic actuators (SPA) with Kresling origami patterns have unique advantages over conventional rigid robots, owing to their adaptability and safety. Inspired by cloning and moving behaviors observed from salps, we proposed an SPA based on a Kresling-like pattern with a rigid skeleton. The elongation and output force were tested, and the effectiveness of the applications with the SPA was evaluated. The proposed SPA consists of rigid skeletons and a soft skin. The rigid skeletons are constructed using layers of Kresling-like patterns, while a novel extensible inserting structure is devised to replace the folds found in conventional Kresling patterns. This innovative approach ensures that the SPA exhibits axial contraction/expansion motion without any twisting movement. To mimic the bionic characteristics of swimming and ingesting progress of salps, the proposed SPA can perform an axial contraction motion without twisting and a controllable bending motion based on multi-layered Kresling-like patterns; to mimic the cloning and releasing life phenomena of salps, the number of layers of Kresling-like patterns is changeable by adding or reducing skeleton components according to the practical needs. The experimental elongation results on the SPA with multiple layers of Kresling-like patterns show that the elongation can increase to above 162% by adding layers; the experimental output force results show that the three-layer SPA can provide 6.36 N output force at an air flow rate of 10 L/min, and the output force will continue to increase as the number of layers of Kresling-like pattern increases or the air flow rate increases. Further, we demonstrate the applications of the SPA in soft grippers, scissor grippers, claw grippers and pipe crawlers. Our proposed SPA can avoid twisting in the radial contraction motion with high elongation and output force, and provide the practical guidance for bio-inspired soft robotic applications. [ABSTRACT FROM AUTHOR]

Unsteady gas-dynamic phenomena in pipelines of complex configuration are widespread in heat exchange and power equipment. Therefore, studying the heat transfer level of pulsating air flows in round and triangular pipes with different turbulence intensities is a relevant and significant task for the development of science and technology. The studies were conducted on a laboratory stand based on the thermal anemometry method and an automated system for collecting and processing experimental data. Rectilinear round and triangular pipes with identical cross-sectional areas were used in the work. Flow pulsations from 3 to 15.8 Hz were generated by means of a rotating flap. The turbulence intensity (TI) of the pulsating flows varied from 0.03 to 0.15 by installing stationary flat turbulators. The working medium was air with a temperature of 22 ± 1 °C moving at a speed from 5 to 75 m/s. It was established that the presence of gas-dynamic unsteadiness leads to an increase in the TI by 47–72% in a round pipe and by 36–86% in a triangular pipe. The presence of gas-dynamic unsteadiness causes a heat transfer intensification in a round pipe by 26–35.5% and by 24–36% in a triangular pipe. It was shown that a significant increase in the TI of pulsating flows leads to an increase in the heat transfer coefficient by 11–16% in a round pipe and a decrease in the heat transfer coefficient by 7–24% in a triangular pipe. The obtained results can be used in the design of heat exchangers and gas exchange systems in power machines, as well as in the creation of devices and apparatuses of pulse action. [ABSTRACT FROM AUTHOR]

The objective of this study is to implement a more realistic integrated analysis model for micro gas turbines by incorporating secondary flow and combustion efficiency into the existing model, which includes main engine components such as the compressor and turbine, and to validate this model by comparing it with test results. The study was based on the JetCat P300-RX, which has a maximum thrust level of 300 N. Simulations were performed using ANSYS CFX, employing the κ-ω SST turbulence model and a mixing plane interface between individual components. The eddy dissipation model (EDM), with a combustion efficiency of 90%, was used as the combustion model. A user subroutine was also applied for the power matching of the compressor and turbine to calculate the fuel flow rate in each iteration. For secondary flow, it was assumed that 3% of the total air flow rate would flow through the secondary path and be applied to the compressor and turbine. Simulations were conducted over a range of 30,000 to 104,000 RPM, with ground conditions evaluated, including altitude-simulated conditions. To validate the analysis model, engine performance metrics such as pressure ratio, air flow rate, fuel flow rate, and exhaust gas temperature (EGT) were compared with test results. The results demonstrated that errors were less than 5% for most engine performance metrics, except for EGT and fuel flow. The discrepancy in EGT was attributed to differences in the sensing methods, while the variation in fuel flow was found to be due to the lubrication system and losses due to the secondary air flow. Consequently, this study confirmed that the integrated simulation model accurately predicts engine performance. The results indicate that the integrated simulation model provides a more realistic prediction of overall engine performance compared to previous studies. Therefore, it can evaluate detailed thermo-fluid properties without the need for component performance maps, enhancing performance evaluation and analysis. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Automotive Digest is the property of Automotive Digest Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The risk of coal spontaneous combustion in goaf is one of the disasters in coal mining, ventilation and extraction often aggravate air leakage from the goaf. Due to the unclear rule of expansion law and air leakage, the risk space for coal spontaneous combustion continues to occur. To investigate the influence of ventilation and extraction on the evolution of the risk space of coal spontaneous combustion (CSC) in goaf, further reveal the characteristics of air leakage and extraction in goaf and obtain the expansion law of CSC risk space. A three-dimensional model of goaf under surface drilling and gas extraction was developed. Using FLUENT numerical simulation software, taking a coal mine in Anhui Province, this study analyzes the influence factors, evolution law, and influence characteristics of CSC through field observations and numerical simulation. The research indicates that ventilation keeps the risk space of CSC expanding. The extraction of single drilling showed a local space expansion, while the extraction of double drilling shows the overall space expansion of the goaf. The air leakage flow path in goaf, air flow velocity vector in working face, gas concentration loss, and gas extraction characteristic parameters are determined. The loss of air leakage along the working surface meets four-stage: "strong in – flow - mixed flow – steady inflow – sudden outflow." It can be determined that the extraction intensity of single drilling should be greater than 34.8 m3/min, and the double drilling should be greater than 18.7 m3/min. The relationship between the coupling influence of ventilation and extraction and the expansion law of CSC risk space is determined, and the maximum risk space width of CSC can be predicted. The research results are of guiding significance for CSC prevention and gas efficient extraction. [ABSTRACT FROM AUTHOR]

Direct air capture (DAC) is a negative emission technology for removing CO2 from the atmosphere to maintain the CO2 level within a reasonable range so as to address greenhouse effects. In this study, the operational optimization of lab‐scale DAC has been investigated using a crossflow air‐liquid contactor loaded with a three dimensionally printed Gyroid packing structure and a potassium sarcosinate solvent. The effects of various parameters, including feed air flow rate, liquid solvent flow rate, contactor geometry, and ambient temperature, are examined. The results demonstrate that the Gyroid packing design achieves comparable CO2 capture performance to conventional packed beds but with a significantly lower pressure drop of up to 77.8%, suggesting its potential as an efficient and cost‐effective solution for gas–liquid contactors in DAC. Additionally, the study explores the climate impact on CO2 capture performance and finds that as the air temperature increases from 35 to 95°F at a fixed relative humidity of 80%, the CO2 capture rate increased from 23.2% to 46.8% with better stability. The research highlights the importance of optimizing contactor design and operational conditions to improve the CO2 capture rate and feasibility of DAC systems as a negative emission technology for addressing greenhouse effects. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos del Centro de Estudios de Diseño y Comunicación is the property of Cuadernos del Centro de Estudios de Diseno y Comunicacion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a comparative analysis of a finned heat exchanger fed with synthetic refrigerant R410a and environmentally friendly refrigerant R290. Analyses of the performance of the heat exchanger operating as an evaporator in a refrigeration system were carried out. Simulation studies were performed using SOLIDWORKS software with the Flow Simulation library. The analysis was conducted for various design parameters of the device. The performance of the exchanger was examined for different fin materials (aluminium alloys: alloy 1060, 1060-H12, alloy 2014, alloy 2024), number of fins (78 and 39), and fin spacings (2.5 mm and 5 mm). The studies were conducted under various operational parameters of the exchanger (varying volume flow of air and refrigerant mass flow). Based on the results obtained, it was found that the material of the exchanger does not significantly affect its performance. The next conclusion is that when the heat exchanger is fed with an environmentally friendly refrigerant, the heat transfer surface area can be reduced by 50%. As a result, the reduction in heat transfer surface area can be achieved by increasing the fin spacing, which will reduce the electricity consumed in the defrost process under operating conditions, or by reducing the size of the exchanger, which will positively translate into a reduction in the weight of the refrigerant in the system. The possibility of reducing the dimensions of the heat exchanger by up to 50% indicates that replacing R410a refrigerant with environmentally friendly R290 is a promising direction for development. It advocates for ongoing investigations to refine these systems and maximize the operational advantages presented by natural refrigerants. [ABSTRACT FROM AUTHOR]

Dryland expansion causes widespread water scarcity and biodiversity loss. Although the drying influence of global warming is well established, the role of existing drylands in their own expansion is relatively unknown. In this work, by tracking the air flowing over drylands, we show that the warming and drying of that air contributes to dryland expansion in the downwind direction. As they dry, drylands contribute less moisture and more heat to downwind humid regions, reducing precipitation and increasing atmospheric water demand, which ultimately causes their aridification. In ~40% of the land area that recently transitioned from a humid region into a dryland, self-expansion accounted for ’50% of the observed aridification. Our results corroborate the urgent need for climate change mitigation measures in drylands to decelerate their own expansion. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION The delayed drying of newly harvested tiger nuts can lead to mold and rancidity. Timely drying is therefore important. However, few studies have analyzed the impact of hot‐air drying on the quality of tiger‐nut oil and starch, making it essential to establish optimal drying conditions.The results showed that the drying temperature was the most important factor affecting the drying speed, followed by drying airflow rate and loading capacity. A logarithmic model can describe the hot‐air drying process of tiger nuts. The oil yield of tiger nut was highest after drying at 60 °C, reaching 22.40%. Meanwhile, the starch extracted from after drying at 60 °C had the highest solubility and expansion rate, 4.77% and 9.74%, respectively. Starch has the highest viscosity after drying at 70 °C, and it forms gel easily after aging.High‐quality tiger nuts should be produced under optimal conditions: a hot‐air drying temperature of 60 °C, an airflow rate of 1.0 m s−1, and a loading capacity of 100 g. The results of this study have practical implications for the effective drying of tiger nuts. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The projected speckle-based three-dimensional digital image correlation method (3D-DIC) is being increasingly used in the reliability measurement of microelectronic packaging structures because of its noninvasive nature, high precision, and low cost. However, during the measurement of the thermal reliability of packaging structures, the thermal airflow generated by heating introduces distortions in the images captured by the DIC measurement system, impacting the accuracy and reliability of noncontact measurements. To address this challenge, a thermal airflow distortion correction model based on the transformer attention mechanism is proposed specifically for the measurement of thermal warpage in microelectronic packaging structures. This model avoids the oversmoothing issue associated with convolutional neural networks and the lack of physical constraints in generative adversarial networks, ensuring the precision of grayscale gradient changes in speckle patterns and minimizing adverse effects on DIC calculation accuracy. By inputting the distorted images captured by the DIC measurement system into the network, corrected images are obtained for 3D-DIC calculations, thus allowing the thermal warpage measurement results of the sample to be acquired. Through experiments measuring topography with customized step block specimens, the effectiveness of the proposed method in improving warpage measurement accuracy is confirmed; this is particularly true when captured images are affected by thermal airflow at 140 °C and 160 °C, temperatures commonly encountered in thermal reliability testing of packaging structures. The method successfully reduces the standard deviation from 9.829 to 5.943 µm and from 12.318 to 6.418 µm, respectively. The results demonstrate the substantial practical value of this method for measuring thermal warpage in microelectronic packaging structures. [ABSTRACT FROM AUTHOR]

With buildings contributing significantly to electricity usage, enabling demand flexibility becomes a challenge, especially when accounting for occupant comfort. This study introduces an innovative co-simulation framework integrating multiple models: heating, ventilation, and air conditioning (HVAC) system, building zone load, indoor airflow, supervisory control, and occupant comfort and behavior. Uniquely, this framework allows for a comprehensive and dynamic analysis of building systems and occupant interactions in demand response events. Using this framework, we conducted a case study using a typical small office building model. Specifically, we focused on three areas: (1) the impact of indoor airflow modeling on energy use, occupant comfort, and behaviors forecasting, (2) the impact of occupant behaviors on demand flexibility, and (3) occupant comfort and behaviors under demand response events. Key performance indicators such as energy use, flexibility factor, durations of occupant discomfort and occupant behaviors were analyzed. Our findings indicated variations in energy usage and occupant comfort within demand flexibility events, marked by uncertainty boundaries, with variability in demand shedding up to 57.9%. We concluded that this framework is suitable for analyzing typical commercial buildings and their HVAC systems in terms of demand flexibility potential under the impact of occupant behaviors. [ABSTRACT FROM AUTHOR]

This study reports satellite evidence for the most northerly blown dust activity yet observed on Earth. A systematic inspection of high‐resolution satellite imagery identified active dust events and their sources >82°N in Peary Land, Greenland. In the absence of any local weather measurements, for all observed dust activity a focus period in April 2020 with multiple dust plumes, reanalysis climate data found the majority of dust events to be associated with wind speeds exceeding a typical threshold value for blowing sand and dust uplift. Wind direction variability points to dust‐raising by cold airflow down‐valley winds, likely from nearby ice masses. [ABSTRACT FROM AUTHOR]

As the important component to guide the airflow in the classifier, installation position of the guide vane determines the width of the classification annular region and influences the flow field distribution. The influence of the guide vane positioning on the flow field in the annular region is analyzed through numerical simulation. The simulation results show the tangential velocities near the inner edge of the guide vanes increase, and the tangential velocity gradient decreases with decrease of the width of the annular region. The increases of turbulent dissipation rate near the guide vanes are beneficial to powder dispersion. However, the increases of turbulent dissipation rate near the rotor cage aren′t conducive to uniformity of the flow field. In case of the narrow annular region, the cut size gradually increases when the width of the annular region increases. However, when the width of the annular region continues to increase, the particle′s residence time become long, and the solid concentration increases significantly to increase the probability of particle aggregation. The reasonable range of the installation diameter of the guide vane in the classifier is between 504 mm and 524 mm. [ABSTRACT FROM AUTHOR]

The unsteady airflow will cause the distortion and delay change of the signal propagation path, resulting in the delay and distortion of the received satellite signal. This will lead to increased ranging and direction finding errors in the positioning system, which will affect the precision and accuracy of the positioning results. Therefore, a new multi-satellite anti-interference hybrid positioning method under the influence of unstable airflow is studied. Preprocess the unstable turbulence data at high altitude, and verify the turbulence data authenticity quickly. The flow field description equation is constructed based on the momentum conservation theorem. The multi-satellite motion equation is established by using the carrier phase observations and satellite antenna phase center coordinates, and the anti-interference hybrid positioning model is constructed. Global Navigation Satellite System (GNSS) technology is introduced to solve the multi-satellite hybrid anti-interference model by using the signals of multiple satellites to calculate the receiver's position, speed and time. The experimental results show that, for static targets, the research method has a small deviation in the positioning of the target N, S and E. When using the mixed positioning of near-earth satellite, medium altitude satellite and geosynchronous satellite, the mean square value of positioning error is always lower than 0.002 cm. For the dynamic target, the method is not disturbed by clutter, and the target is stably located. Moreover, the proposed method has lower localization delay and higher localization efficiency. [ABSTRACT FROM AUTHOR]

uDALES is an open-source multi-physics microscale urban modelling tool, capable of performing large-eddy simulation (LES) of urban airflow, heat transfer, and pollutant dispersion. We present uDALES v2.0, which has two main new features: (1) an improved parallelisation that prepares the codebase for conducting exascale simulations and (2) a conservative immersed boundary method (IBM) suitable for an urban surface that does not need to be aligned with the underlying Cartesian grid. The urban geometry and local topography are incorporated via a triangulated surface with a resolution that is independent of the fluid grid. The IBM developed here includes the use of wall functions to apply surface fluxes, and the exchange of heat and moisture between the surface and the air is conservative by construction. We perform a number of validation simulations, ranging from neutral, coupled internal–external flows and non-neutral cases. We observe close agreement with the relevant literature, both in cases in which the buildings are aligned with the Cartesian grid and when they are at an angle. We introduce a validation case specifically for urban applications, for which we show that supporting non-grid-aligned geometries is crucial when solving surface energy balances, with errors of up to 20 % associated with using a grid-aligned geometry. [ABSTRACT FROM AUTHOR]

In this paper, we present a cost-effective system for monitoring and controlling alkaline electrolyzers, intending to improve hydrogen gas production on a laboratory scale. Our work includes two main innovations. Firstly, we suggest an approach to calibrate a standard air flow meter to accurately measure the flow of hydrogen-rich gas from electrolyzers, improving measurement accuracy while keeping costs low. Secondly, we introduce a unique cascade control method to manage hydrogen-rich gas production in the electrolyzer, ensuring precise control over gas flow rates. By combining affordable, energy-efficient devices with a PI control system, we achieve efficient gas production through electrolysis, replacing manual control approaches. Experimental results confirm the effectiveness of our cascade control method, demonstrating stable operation with minimal errors. These results provide a foundation for further research into control strategies to enhance the performance of electrolytic cells. [ABSTRACT FROM AUTHOR]

In this study, tubes filled with PCM as a thermal energy storage unit with an indirect air heater are used to store and recover solar thermal energy. Two different configurations of PCM-filled tubes (inline and staggered) in the unit are considered and compared with the PCM-filled plate unit. In all cases, the amount of the PCM is the same. The effects of airflow rate, diameter of tubes and inlet temperature on the charging and discharging rates are studied. Results showed that the PCM tube unit is more efficient than the PCM plate unit. The thermal performance is enhanced with the increase of the air mass flow rate. Results also revealed that the phase change rate in staggered configurations is between 7% and 36% (depending on the airflow rate) greater than that in the inline ones. By reducing the tube diameter, the melting and solidification processes are performed more quickly due to the rise of the overall heat transfer surface area. The influence of the temperature difference between the inlet air and PCM is more effective than the other considered effects where the 10 °C increase of the temperature difference enhances the charging rate by a factor of 2. [ABSTRACT FROM AUTHOR]

The oxidation kinetics and oxide scale morphology of the Si 2 BC 3 N/Ta 4 HfC 5 ceramics sintered by hot-pressing were explored at 1000 °C and 1500 °C in flowing air. Dense Si 2 BC 3 N/Ta 4 HfC 5 ceramic sintered at 1900 °C with fine grain sizes shows the optimal oxidation resistance both at 1000 °C and 1500 °C. When oxidized at 1000 °C, the formation of a porous oxide layer of Ta 2 O 5 , Hf 6 Ta 2 O 17 and HfO 2 containing amorphous SiO 2 are primarily responsible for the unsatisfying oxidation resistance of the composite. A highly oxidation resistance component like Si 2 BC 3 N can promote the oxidation resistance of Ta 4 HfC 5 at 1500 °C, thanks to the formation of a dense and continuous tantalum-hafnium silicate glass. The oxidation kinetic curve at 1500 °C can be described by a parabolic law whilst the oxidation process is controlled by the diffusion rate of oxygen through the oxide layer; however, the oxidation reaction rate governs the oxidation progress at 1000 °C via a linear oxidation kinetics. • Different oxide phases of Si 2 BC 3 N/Ta 4 HfC 5 ceramics form when oxidized at 1000 °C and 1500 °C, respectively. • Si 2 BC 3 N/Ta 4 HfC 5 ceramics has a better oxidation resistance than Ta 4 HfC 5 when oxidized at 1500 °C. • Si 2 BC 3 N/Ta 4 HfC 5 ceramic sintered at 1900 °C has the best oxidation resistance because of the fine grain size and good relative density. [ABSTRACT FROM AUTHOR]

Large-span arch greenhouse has gained widespread application in fruit and vegetable production in recent years, due to the convenient facility operation, high land use efficiency, suitability for multiple coverings, and external heat preservation. However, internal turbulence can often occur in the expansion of the span and height of the large-span arch greenhouse. The resulting uniformity of the greenhouse environment can then affect the efficient production of greenhouse crops. In this study, a multi-field coupled computational fluid dynamics (CFD) model was constructed to integrate the facility structure and tomato plant aerodynamics, according to agricultural industry demand. The research object was selected as the 20 m span large-span arch greenhouse in Laiwu district, Jinan City, Shandong province (36.14° N, 117.28° E), China. A systematic investigation was carried out to explore the influence of the height of the arch greenhouse on the spatial and temporal distribution and evolution of the turbulent structure inside the large-span arch greenhouse. An analysis was also made to clarify the relationship between the wind and the temperature distribution, turbulence intensity, summer ventilation, and cooling efficiency, and the height of the arch greenhouse. Seven kinds of large-span arch greenhouse were established with 4.5, 5.0, 5.5, 6.0, 6.5, 7.0 and 7.5 m heights. The results show that there was turbulent behavior in the large-span arch greenhouses, indicating the mostly double vortex in the section. The air-flow entered the greenhouse via the bottom vent on the windward side, then ascended along the lower side of the greenhouse film, and finally descended towards the roof area. There was a tendency for the stabilization in the position of the inflection point, as the ridge height increased beyond 6.0 m. Therefore, the better uniformity of air flow and temperature distribution were, the higher the uniformity of the greenhouse was. The large-span arch greenhouse with a height of 6.0 m shared the highest average flow velocity at the crop canopy, which was in the appropriate range and relatively high. The average temperatures were also relatively low, which were 0.404 ℃ and 0.026 ℃ lower than those of the arch greenhouse with a height of 5.5 and 6.5 m, respectively. The turbulence intensity of the large-span arch greenhouse with a height of 4.5-5.5 m was significantly higher than that with a height of more than 6.0 m. There was a small difference, after the ridge height exceeded 6.0 m. Once the height of the greenhouse was 4.5 m, the ventilation efficiency was 2.24. After that, the efficiency of ventilation decreased with the increase in the height of the greenhouse. There was a relatively high value when the ridge height reached 6.0 and 6.5 m. The ridge height of 7.0 m corresponded to the lowest ventilation efficiency of 1.60. The large span greenhouse with a 4.5 m ridge height exhibited the higher ventilation efficiency, but the lower air change rate. The large span greenhouse with a 7.5 m ridge height shared the lower air change rate and ventilation efficiency. The outstanding ventilation and cooling performance of the large-span arch greenhouse in summer was determined by many factors. In a 20 m long-span arch greenhouse with shoulder, a better structure was achieved with the ridge height of 6.0-6.5 m and the ridge height of 6.0 m, in order to better consider the factors of economy and safety. The finding can provide a strong reference to optimize a similar greenhouse configuration in the construction of the large-span arch greenhouse. [ABSTRACT FROM AUTHOR]

AbstractGarbage incineration power generation is utilized to dispose of multi-source organic solid waste. This work constructed a mathematical model for a 750 t/d garbage incinerator to reveal the coupled response between the boiler and furnace sides. Field experiments validated the model, exploring various operating conditions including different loads, fuel blending ratios, primary air, and internal flue gas recirculation (IGR) air flow rates. Increasing the load by 9.1% raised furnace heat exchange by 4.0% but reduced economizer heat exchange by 19.0%. Introducing waste cloth strips and paper mill waste enhanced furnace water-cooled wall heat transfer but reduced economizer heat exchange. A 10.8% rise in primary air flow increased superheater heat exchange by 7.8%. Similarly, a 21.3% rise in IGR air flow increased economizer heat exchange by 9.0%. The temperature rise and enthalpy rise in the superheater were higher when the low calorific value of the fuel was higher. Increasing primary air velocity enhanced heat transfer, raising the outlet temperature of the medium-temperature superheater, necessitating an increase in secondary water spray to adjust the outlet temperature of the high-temperature superheater. This work provides guidance for the design and practical operation of multi-source solid waste incinerators. [ABSTRACT FROM AUTHOR]

Background: At the time of the COVID-19 pandemic, devastating incidents increased due to frequent oxygen administration to patients. The dangers associated with the use of oxygen, especially through local enrichments and formation of "oxygen clouds", have been well understood for years. Nevertheless, dramatic incidents continue to occur, since fire hazard increases exponentially with oxygen concentrations above 23%. Rescue helicopters are at a particular high risk, because of technical reasons such as oxygen use in a very small space, surrounded by kerosene lines, electronic relays and extremely hot surfaces. Methods: In this study three different sized rescue helicopter models (Airbus H135, H145 and MD902) were examined. Oxygen enrichment in the cabin was measured with an oxymeter during a delivery rate of 15 l/min constant flow for 60 min. Furthermore, the clearance of the enriched atmosphere was tested in different situations and with different ventilation methods. To make the airflow visible, a fog machine was used to fill the helicopter cabin. Results: Oxygen accumulation above 21% was detected in every helicopter. After 10–15 min, the critical 23% threshold was exceeded in all three aircrafts. The highest concentration was detected in the smallest machine (MD902) after 60 min with 27.4%. Moreover, oxygen clouds persisted in the rear and the bottom of the aircrafts, even when the front doors were opened. This was most pronounced in the largest aircraft, the H145 from Airbus Helicopters. Complete and rapid removal of elevated oxygen concentrations was achieved only by cross-ventilation within 1 min. Conclusions: Oxygen should be handled with particular care in rescue helicopters. Adapted checklists and precautions can help to prevent oxygen accumulation, and thus, fatal incidents. To our knowledge, this is the first study, which analyzed oxygen concentrations in different settings in rescue helicopters. [ABSTRACT FROM AUTHOR]

The study analyzed available data series of the Sava River's water temperature measured at the Zagreb gauging station. Official data from the Croatian Meteorological and Hydrological Service (DHMZ) in Zagreb were utilized. Over the 73 years from 1948 to 2020, there are only 53 years with complete measurement records. Despite this limiting fact, it was considered important to analyze the behavior of the Sava River's water temperatures in Zagreb over the past 70 years, during which a significant increase in air temperatures has been observed in the region, particularly in the city of Zagreb. Analyses were conducted on the characteristic (minimum, mean, and maximum) water temperatures over timescales of years, months, and days. The relationship between water temperatures (TW) and air temperatures (TA) measured at the Grič Observatory and the flows (Q) of the Sava River in Zagreb were investigated. A trend of rising water temperatures was observed throughout the entire period from 1948 to 2020, with the intensity significantly increasing in the recent period starting from 1988. The trend of rising air temperatures is the primary driver of the increase in the water temperatures of the Sava River in Zagreb. However, the impact of reduced water flow, especially during the warm season, should not be overlooked. This effect is amplified by the observed trend of decreasing minimum flows of the Sava during the warm season, from June to September. As a result, the most significant rise in water temperatures of the Sava River in Zagreb occurs during prolonged low-water summer periods, particularly in July. A strong trend has been observed in the increasing number of days per year with mean daily water temperatures of the Sava River exceeding 20 °C. This higher water temperature occurs increasingly earlier in the year, lasts longer, and ends later, often extending into September. [ABSTRACT FROM AUTHOR]