Continuous Water Spray Research Articles

Experimental study of the strategy of C6F12O and water mist intermittent spray to suppress lithium-ion batteries thermal runaway propagation

Extinguished lithium-ion battery fires can experience temperature rebound and re-ignition, necessitating proper fire extinguishing and cooling measures for battery safety. This study introduces a novel approach that integrates C6F12O and water mist as a strategy to prevent the spread of thermal runaway in lithium-ion batteries, evaluating the fire-suppression and cooling ability under various intermittent spray modes. The findings demonstrate that the strategy has a stronger suppression effect compared to continuous water spray and could prevent the spread of thermal runaway. C6F12O can extinguish fires in just 1 s. During the cooling phase, the cooling capacity generally decreases with increasing cycle period and duty cycle. Among different cycle periods, C6F12O combined with intermittent water mist spray (DC = 0.5, Pt = 2 s) exhibited the most effective cooling, significantly reducing peak temperature and providing the highest heat suppression. In terms of duty cycles, C6F12O combined with intermittent water mist spray (DC = 0.1, Pt = 20 s) achieved the longest cooling duration, lowering the temperature of Cell #3 to below 50 °C. The combination of C6F12O and intermittent water mist spray rapidly extinguishes flames, maximizes the cooling impact of water mist, and ultimately hinders the propagation of thermal runaway.

Degradation of superhydrophobic aluminium overhead line conductor surfaces

AbstractIt has been shown that noise emissions from HV overhead line conductors can be reduced under rain conditions by making their surfaces superhydrophobic. The working environment makes ensuring the longevity of any treatment a major challenge. The degradation of various superhydrophobic surfaces generated by applying a superhydrophobic coating and patterning microscale channels is assessed under an AC electric field (18 kV/cm) with continuous water spray. By examining the droplet distribution on the surfaces during the degradation and the surface roughness before and after degradation, the authors demonstrate that no water droplets were found on the microscale patterned surface, but droplets were formed on the coated surface after degradation. The surface roughness reduction of the coated surface and microscale patterned surface was 29.8% and 11.3%, respectively, indicating that the microscale patterned surface has better durability than the superhydrophobic coating under the AC electric stress.

Comparative Evaluation of the Effectiveness of Three Commercially Available Desensitizing Mouthwash on Dentinal Tubule Occlusion: An In Vitro Scanning Electron Microscopic Study.

To compare and evaluate the effectiveness of three commercially available desensitizing mouthwashes on dentinal tubule occlusion in vitro using a scanning electron microscope (SEM). Twenty-seven premolar maxillary teeth were collected and cleaned to remove debris and tissue using an ultrasonic scaler. Enamel was removed with the help of a high-speed plain cut tungsten carbide fissure bur under continuous water spray. Dentinal discs measuring 5 mm × 5 mm × 3 mm were prepared from the coronal region of the extracted teeth using a double-sided carborundum disc and straight micromotor handpiece. Using carborundum paper, the discs were polished and washed with distilled water. The discs were etched using 37% phosphoric acid to remove any smear layer that was caused by the grinding process and to simulate dentinal hypersensitivity by opening the dentinal tubules. The specimens were again washed and stored in distilled water until use. Samples were then randomly allocated into Group A: calcium sodium phosphosilicate mouthwash, Group B: potassium nitrate mouthwash, and Group C: dipotassium oxalate monohydrate mouthwash. The specimens were immersed in a test tube filled with the respective mouthwash and vigorously shaken for 60 s for simulating the natural mouth rinsing action. This procedure was repeated for 7 days, twice daily. To compare and assess the proportion of dentinal tubule occlusion, all the samples were processed and examined under an SEM. The efficacy of the mouthwash on the obliteration of dentinal tubules was compared using the Kruskal-Walis analysis of variance test followed by the post hoc Mann-Whitney U test for pairwise comparison. Group A showed completely occluded tubules in 5 (55.6) and mostly occluded tubules in 4 (44.4). Group B showed mostly occluded in 4 samples (44.4) and partially occluded in 5 samples (55.6) and Group C showed completely occluded tubules in 3 samples (33.3) and mostly occluded tubules in 6 samples (66.7). A P value of 0.05 or less is regarded as statistically significant. *P ≤ 0.05 is statistically significant. Between Group A and Group B as well as between Group B and Group C, there was a statistically significant difference. However, a statistically significant difference between Group A and Group C does not exist. The calcium sodium phosphosilicate group was shown to have the most occlusion of the dentinal tubule, followed by dipotassium oxalate monohydrate and potassium nitrate group.

Experimentally evaluating the performance of single slope solar still with glass cover cooling and square cross-section hollow fins

Although water is the source of life, most water resources are salty or undrinkable. Treating the salty water to produce fresh water is typically a cost-intensive process. As a more effective solution, solar energy evaporates the salty water and condensates the vapor as freshwater by solar stills. This article encompasses an experimental evaluation of the performance of single slope solar still with a square cross-section (SSSS) hollow fin attached to an absorber plate. The article also experimentally estimates the potential of cooling the glass cover. The squared hollow fins have dimensions of (25 mm in width, 25 mm in height and 2 mm in thickness). The cooling mechanisms under consideration were of two types: continuous water spray and pulsed glass cooling (30 s/30 min), (30 s/20 min), (30 s/10 min), and (30 s/5 min). According to the results, there was an enhancement in productivity of 40% as the SSSS integrated with fins, in contrast to conventional solar still. Furthermore, enhancement of 13.3%, 17.8%, 36.7%, 24.2%, and 10%, respectively were achieved by the integration of SSSS with glass cooling by spraying at different rates (30 s/30 min), (30 s/20 min), (30 s/10 min), (30 s/5 min), and continuous water spray system. This highlights that pulse water cooling yields better outcomes than continuing with the timing of (30 s/10 min). The combination of both mechanism upgrades has induced a further enhancement of 61.3% in contrast to that of a conventional single slop solar still (CSS).

Efficiency increase of photovoltaic systems by means of evaporative cooling in a back-mounted chimney-like channel

An increased cell temperature due to solar irradiance causes a decrease in conversion efficiency of a solar cell, i.e., a loss in electrical output. In this study, we present a cooling method for a cell temperature decrease by means of water droplet evaporation in a chimney-like channel attached to the back side of a photovoltaic module. The system design process starts with shadowgraph imaging of various atomizer nozzles. The optimal atomizer nozzle is then integrated into a laboratory test setup for parameter studies of the cooling performance and of the water usage. A cooling approach with two pin-jet nozzles positioned at the inlet and outlet of the cooling channel facing each other yields the best result in terms of water usage per efficiency increase. The efficiency of the solar cell is increased by 8.7% consuming 9.2 l of water per hour and square meter of the photovoltaic module. The evaporation rate limits the amount of moisture absorbed by the air in the channel to only 10% of the water needed for effective atomization. The excess water settles as a water film in the channel and on the back side of the photovoltaic module, causing an additional film cooling effect. A comparison of the optimized cooling system with results from the literature for continuous water spray cooling shows six times less water usage per percent efficiency increase. With the use of the chimney-like channel, deposits such as moss or calcium do not occur on the front side of the photovoltaic module. Moreover, the risk of stress cracks in the glass surface due to temperature gradients is avoided. The current data give a strong indication that ongoing optimization with custom designed atomizer nozzles will further reduce the water usage towards a profitable system operation.

Experimental verification of the potential of superhydrophobic surfaces in reducing audible noise on HVAC overhead line conductors

Overhead line conductors can generate audible noise across a wide frequency spectrum as a result of elevated electric fields at the conductor surface. Such fields are enhanced by the presence of surface defects, insects, water drops and pollution. Within this paper, the impact of a superhydrophobic coating on the audible noise produced by an overhead line conductor is examined. Noise levels from a conductor coated with a superhydrophobic coating were compared to those from a bare conductor in a semi-anechoic chamber. The conductors were energised at voltages to provide surface electric fields ranging from 6 kV/cm to 21 kV/cm (rms). With a continuous water spray system depositing droplets on the conductor surface, the frequency domain sound pressure level, overall sound pressure levels and corona discharge magnitude were measured. It is demonstrated that the use of a superhydrophobic coating reduced audible noise levels and corona discharge magnitude, especially at electric fields above 14 kV/cm. The image analysis suggests that the water drop size distribution and the position of surface droplets on the conductor circumference play an important role in the magnitude of audible noise.

The effect of the NiTi alloy modification and the taper of endodontic instruments on the cyclic fatigue resistance

Background/Aim: The fracture of engine-driven instruments during root canal treatment has been tried to be eliminated by developing the manufacturing process of the files. The aim of this study was to assess cyclic fatigue resistance (CFR) of the two different rotary filesEdgeSequel™ Sapphire (ES) and Race® Evo (RE)which are produced by two different manufacturing technologies. Material and Methods: While RE is manufactured from heat-treated NiTi alloy with the electropolished surface, ES undergoes a non-disclosed thermal treatment called FireWire heat treatment. The CFRs of ES and RE comprising of similar tip size and taper (15/.04 and 25/.04) were compared on a cyclic fatigue device with an artificial stainless-steel canal (60° curvature, 5 mm radius, 1.5 mm width, and 3.0 mm depth). The continuous water spray with a syringe at 35.5°C was used to decrease the friction and to simulate in vivo conditions. All procedures were performed at recommended speed and torque for both files until fracture occurred. The time to failure (TF) was recorded and the number of cycles to failure (NCF) was calculated. The Weibull calculations (Weibull modulus, R2, predicted cycles, and time for 99 % survival) for NCF and TF were also done. The data were statistically analyzed with the independent two-sample t-test and the paired two-sample t-test. The significance level was set at p < 0.05. Results: Both ES and RE showed a better CFR in 15/.04 tip size than 25/.04 (P < 0.05). The TF of the ES were higher than the RE (P < 0.05). The highest and lowest Weibull modulus values were obtained with RE 15/.04 and RE 25/.04, respectively. Conclusions: Both the tip diameter and alloy modification of the instruments affected the CFR. FireWire heat treatment was associated with longer TF. The bigger the tip diameter, the lower the CFR for both tested products.

Waxing the soot: Practical fabrication of all-organic superhydrophobic coatings from candle soot and carnauba wax

Commercial application of superhydrophobic coatings is hindered by insufficient durability and use of materials with high costs and limited availability. In this study, we report a robust water impact resistant all-organic superhydrophobic coating that is prepared from low-cost colloidal dispersion composed of carnauba wax and candle soot. The colloidal dispersion is stable and can be spray-coated onto virtually any surfaces. The coated surfaces exhibit superhydrophobicity with a water contact angle of 172° and sliding angle of 3°, and retain superhydrophobicity even after 400 cycles of continuous water spray with an impact pressure of 7.4 kPa. The synergetic combination of candle soot and carnauba wax, together with the deposition method, solvent used to disperse materials, and spray-coating distance are critically important for the superhydrophobicity and mechanical durability. The robustness of the coatings emerges from the two-tier hierarchical structure of the dried particles which is formed by evaporation induced self-assembly of wax molecules and candle soot nanoparticles. Applications in self-cleaning and oil/water separation are demonstrated, where a coated membrane can be continuously operated, solely driven by gravity, and can separate common organic liquids such as hexane and toluene from water with a separation efficiency of more than 90 % at a high flux of 1061 L / (m2 h).

Absence of a continuous water spray system does not influence the microbiological contamination of the conveyor belts in chicken slaughterhouses

The objective was to evaluate whether the absence of a water spray affects the microbial contamination on chicken conveyor belts in slaughterhouse. A total of 1280 samples from modular and smooth conveyor belts, with and without water spray, were evaluated in four slaughterhouses in Brazil. Superficial swabs of conveyor belts were performed at the indicated time periods (T0 - 5:00 a.m; T1 - 9:00 a.m; T2 - 5:00 p.m.; and T3 - 10:00 p.m.) and submitted to counting of mesophiles, Enterobacteriaceae, coliforms, and E. coli. The data were evaluated by measuring the increment (positive or negative) in contamination between the periods and comparing the means of the conveyor belts with and without water spray. On the modular conveyor belts, the absence of water spray allowed for a significant increase in the counts only in the T2–T3 interval for coliforms and E. coli. On the smooth conveyor belts, the absence of water spray allowed for a significant increase in Enterobacteriaceae counts only in the T2–T3 interval. At the other intervals, absence in the water had no influence on the indicator counts. These results demonstrated that the use of a water spray system on conveyor belts does not influence the contamination count.

Effect of super short pulse Er:YAG laser on human dentin--Scanning electron microscopy analysis.

This study evaluated the effect of different pulse widths in the morphological characteristics of human dentin irradiated with Er:YAG in cavity preparation protocols and dentin pretreatment. Dentin discs with 2 mm thickness were obtained from 18 human molars. The experimental groups were composed from two variables: (1) clinical protocol-cavity preparation (E = 200 mJ/20 Hz)-and pretreatment (E = 80 mJ/2 Hz); and (2) pulse duration-50, 300, and 600 μs. This formed six experimental groups (n = 3): G1 (E = 200 mJ/20 Hz/50 μs); G2 (E = 200 mJ/20 Hz/300 μs); G3 (E = 200 mJ/20 Hz/600 μs); G4 (E = 80 mJ/2 Hz/50 μs); G5 (E = 80 mJ/2 Hz/300 μs); G6 (E = 80 mJ/2 Hz/600 μs). The samples were irradiated with the Er:YAG laser by noncontact mode at a focal distance of 7 mm from the target point under continuous water spray (60% water and 40% air). After the irradiation, they were processed for scanning electron microscopy (SEM). Morphological analysis showed an irregular dentin surface, absence of smear layer with opening of the exposure of dentinal tubules and protruding peritubular dentin-without indications of changes for all protocols used. Regardless of the analyzed experimental group, the dentin surface showed a microretentive morphology characteristic of ablation. The G1 and G4 showed a rougher surface when compared to other groups. Finally, we concluded that the pulse width can influence the morphological characteristics of the irradiated dentin tested in different clinical indications. The larger surface irregularity caused by regulation with less pulse width (50 µs) seems more appropriate to get a microretentive pattern necessary for successful adhesives restoration procedures.

The freezing process of continuously sprayed water droplets on the superhydrophobic silicone acrylate resin coating surface

This study conducted experiments on freezing process of water droplets on glass slides covered with superhydrophobic coatings under the continuous water spray condition in the artificial climatic chamber which could simulate low temperature and high humidity environments. The freezing mechanism and freezing time of water droplets under the condition of continuous spray were observed by the microscope and were compared with those of the single static droplet. Then, differences of freezing process between continuously sprayed droplets and single static droplet were analyzed. Furthermore, the effects of static contact angle (CA), contact angle hysteresis (CAH) and roughness of the superhydrophobic coating surface on the freezing time of continuously sprayed droplets were explored. Results show that the freezing process of the continuously sprayed droplets on the superhydrophobic coating started with the homogeneous nucleation at gas–liquid interfaces. In addition, the temperature difference between the location near the solid–liquid interface and the location near the gas–liquid interface was the key factor that influenced the ice crystallization mechanism of water droplets. Moreover, with the larger CA, the smaller CAH and the greater roughness of the surface, droplets were more likely to roll down the surface and the freezing duration on the surface was delayed. Based on the findings, continuous water spray is suggested in the anti-icing superhydrophobic coatings research.

Measurements of erbium laser-ablation efficiency in hard dental tissues under different water cooling conditions

Laser triangulation measurements of Er:YAG and Er,Cr:YSGG laser-ablated volumes in hard dental tissues are made, in order to verify the possible existence of a "hydrokinetic" effect that has been proposed as an alternative to the "subsurface water expansion" mechanism for hard-tissue laser ablation. No evidence of the hydrokinetic effect could be observed under a broad range of tested laser parameters and water cooling conditions. On the contrary, the application of water spray during laser exposure of hard dental material is observed to diminish the laser-ablation efficiency (AE) in comparison with laser exposure under the absence of water spray. Our findings are in agreement with the generally accepted principle of action for erbium laser ablation, which is based on fast subsurface expansion of laser-heated water trapped within the interstitial structure of hard dental tissues. Our measurements also show that the well-known phenomenon of ablation stalling, during a series of consecutive laser pulses, can primarily be attributed to the blocking of laser light by the loosely bound and recondensed desiccated minerals that collect on the tooth surface during and following laser ablation. In addition to the prevention of tooth bulk temperature buildup, a positive function of the water spray that is typically used with erbium dental lasers is to rehydrate these minerals, and thus sustaining the subsurface expansion ablation process. A negative side effect of using a continuous water spray is that the AE gets reduced due to the laser light being partially absorbed in the water-spray particles above the tooth and in the collected water pool on the tooth surface. Finally, no evidence of the influence of the water absorption shift on the hypothesized increase in the AE of the Er,Cr:YSGG wavelength is observed.

Removal effects of the Nd:YAG laser and Carisolv on carious dentin.

The purpose of this study was to investigate the removal effect of the Nd:YAG laser irradiation and Carisolv on carious dentin. Many previous studies have reported several simple and alternative techniques, such as lasers and chemicals, for caries removal. Carisolv was applied on the surface of 20 extracted human anterior and molar teeth for 1 min and then the Nd:YAG laser was irradiated with a continuous water spray for another 1 min. The energy densities were varied from 2 to 6W with a repetition rate of 20 pps. As caries removal progressed, the cavity was carefully assessed by DIAGNOdent. Each lesion was photographed before and after treatment, and the treated cavity was observed microscopically using a stereoscope and with scanning electron microscope (SEM). Thermal change at the time of laser irradiation was measured by thermovision. Our results revealed that application of Carisolv followed by Nd:YAG laser irradiation at 4-6W pulse energy effectively removed dentin caries. The total procedure was usually repeated once or twice for complete caries removal. From the SEM study, it was found that the cavity surface treated with the laser revealed various patterns of microirregularity, often accompanied by microfissure propagation. There was also no smear layer. It was revealed that Nd:YAG laser and Carisolv could provide an alternative technique for caries removal instead of the conventional mechanical drilling and cutting.

Reliable fiber optics for the adverse nuclear environment

Optical fiber system applications have progressed beyond massive production for long-haul telecommunications systems to special systems for military use. The environmental requirements for military systems are extreme. Aircraft systems must endure extreme shock during takeoff and landing on aircraft carriers and thermal shock during a rapid climb from the desert floor to 50,000 ft. Ship systems must weather continuous salt water spray, and space systems must survive the natural space radiation environment. All these systems as well as fixed and mobile ground-based installations may be required to endure the potential threat from nuclear weapons. Research efforts have improved the reliability and survivability of fiber optic systems under these adverse conditions. Radiation test results over extreme temperature ranges have verified that optical fibers have been developed to meet the most adverse of conditions. The establishment of proper test procedures and appropriate evaluation techniques will provide reliable fiber optic components for the adverse nuclear environment.

A preliminary study of the disintegration of dental cements by continuous water spray.

A preliminary study of the disintegration of dental cements by continuous water spray.