BACKGROUND This case of gestational gingival tumor is huge and extremely rare in clinical practice.As the growth location of this gingival tumor is in the upper anterior tooth area,it seriously affects the pregnant wo...BACKGROUND This case of gestational gingival tumor is huge and extremely rare in clinical practice.As the growth location of this gingival tumor is in the upper anterior tooth area,it seriously affects the pregnant woman's speech and food,causing great pain to the patient.The use of Nd:YGA water mist laser to remove the gingival tumor resulted in minimal intraoperative bleeding,minimal adverse reactions,and good postoperative healing,which is worthy of clinical promotion and application.CASE SUMMARY The patient,a pregnant woman,reported a large lump in her mouth on the first day of postpartum treatment.Based on medical history and clinical examination,the diagnosis was diagnosed as gestational gingival tumor.Postoperative pathological biopsy also confirmed this diagnosis.The use of Nd:YAG water mist laser to remove the tumor resulted in minimal intraoperative bleeding,clear surgical field of view,short surgical time,and good postoperative healing.CONCLUSION In comparison to traditional surgery,Nd:YAG water mist laser surgery is minimally invasive,minimizes cell damage,reduces bleeding,ensures a clear field of vision,and virtually eliminates postoperative edema,carbonization,and the risk of cross infection.It has unique advantages in oral soft tissue surgery for pregnant patients.Therefore,the clinical application of Nd:YAG water mist laser for the treatment of gestational gingival tumors is an ideal choice.展开更多
To thoroughly study the extinguishing effect of a high-pressure water mist fire extinguishing system when a transformer fire occurs,a 3D experimental model of a transformer is established in this work by employing Fir...To thoroughly study the extinguishing effect of a high-pressure water mist fire extinguishing system when a transformer fire occurs,a 3D experimental model of a transformer is established in this work by employing Fire Dynamics Simulator(FDS)software.More specifically,by setting different parameters,the process of the highpressure water mist fire extinguishing system with the presence of both diverse ambient temperatures and water mist sprinkler laying conditions is simulated.In addition,the fire extinguishing effect of the employed high-pressure water mist system with the implementation of different strategies is systematically analyzed.The extracted results show that a fire source farther away fromthe centerline leads to a lower local temperature distribution.In addition,as the ambient temperature increases,the temperature above the fire source decreases,while the temperature and the concentrationof theupperflue gas layer bothdecrease.Interestingly,after thehigh-pressurewatermist sprinkler begins to operate,both the temperature distribution above the fire source and the concentration of the flue gas decrease,which indicates that the high-pressure water mist system plays the role of cooling and dust removal.By comparing various sprinkler laying methods,it is found that the lower sprinkler height has a better effect on the temperature above the fire source,the temperature of the upper flue gas layer,and the concentration of the flue gas.Moreover,when the sprinkler is spread over thewhole transformer,the cooling effect on both the temperature above the fire source and the temperature of the upper flue gas layer is good,whereas the change in the concentration of the flue gas above the fire source is not obvious compared to the case where the sprinkler is not fully spread.展开更多
Combined effects of obstacles and fine water mist on a methane-air explosion of a semi-closed pipe were investigated experimentally.In this study,the diameter of the water mist,the location,and the number of obstacles...Combined effects of obstacles and fine water mist on a methane-air explosion of a semi-closed pipe were investigated experimentally.In this study,the diameter of the water mist,the location,and the number of obstacles was considered.The results demonstrated that 5 μm water mist present a significant suppression affected while 45 μm shows a slight promotion effected on a gas explosion of the condition without obstacles.In the presence of an obstacle,however,the inhibitory effect of 5 μm water veils of mist dropped significantly during flame propagation,and the effect of 45 μm water veils of mist changed from the enhancement of inhibition,and its inhibitory effect was significant.The inhibitory effect of 45 μm water veils of mist on gas explosion weakened firstly and then enhanced with the increasing distance between obstacle location from the ignition location as well as in several obstacles.展开更多
In order to study the extinguishing performance of high-pressure-water-mist-based systems on the fires originating from power transformers the PyroSim software is used.Different particle velocities and flow rates are ...In order to study the extinguishing performance of high-pressure-water-mist-based systems on the fires originating from power transformers the PyroSim software is used.Different particle velocities and flow rates are considered.The evolution laws of temperature around transformer,flue gas concentration and upper layer temperature of flue gas are analyzed under different boundary conditions.It is shown that the higher the particle velocity is,the lower the smoke concentration is,the better the cooling effect on the upper layer temperature of flue gas layer is,the larger the flow rate is and the better the cooling effect is.展开更多
The effects of a fine water mist environment in a semi-confined blast chamber on the chemical and thermodynamic processes following detonation of a 20 g PE4 explosive charge have been investigated.The effects were qua...The effects of a fine water mist environment in a semi-confined blast chamber on the chemical and thermodynamic processes following detonation of a 20 g PE4 explosive charge have been investigated.The effects were quantified by the analysis of pressure profiles recorded where several parameters including arrival time of the shock at the sensors, peak overpressures, specific impulse of the positive phase, period of the negative phase and the specific impulse of the multiple reflections were quantified.The effect of the fine water mist on the arrival time, peak pressures and the specific impulse of the positive phase agrees with previous findings in literature. In this paper, the focus is on the implications of the fine water mist on the negative phase and the impulse of multiple pressure reflections. The period of the negative phase was found to have increased by 40% and with higher negative peak pressure in the mist condition compared to the atmospheric condition. The activities of the multiple pressure reflections were found to have decreased considerably, both in number and in amplitude leading to lower impulses(by about 60%) for the water mist conditions.展开更多
The main objective of the present study was introduced water mist suppressiontechnology to prevent and control gas burning which occurred during drilling at Wu20160working-face in No.10 coal mine of Pingdingshan Ltd.....The main objective of the present study was introduced water mist suppressiontechnology to prevent and control gas burning which occurred during drilling at Wu20160working-face in No.10 coal mine of Pingdingshan Ltd..Based on the self-developed ex-periment platform,a series of fire suppression tests to evaluate the performance of a watermist system were conducted.The detailed measurements of the spray characteristics,i.e.,the Sauter Mean Diameter(SMD),the velocity and spray angle which are the main pa-rameters considered in the Study,were obtained by using LS-2000 Sizer.The amount ofwater consumed and the water flux density distribution over the cross section downstreamthe nozzle exit were measured by cup collector method.The operating pressure of thewater mist nozzle is set to 0.5 MPa,the droplet SMD of 104 pm,the water flux density dis-tribution from 0.71 to 8.47 L/(m^2.min),the average velocity of 2.14 m/s.The experimentalresults show that the averaged time required for extinguishment is 3.14 s,and the corre-sponding amount of water used during fire test is about 0.11 kg.The gas fire suppressionsystem reduces the temperature in combustion chamber of the experimental apparatusbelow the ignition point of the gas,which can effectively avoid the occurrence of the gasfire in coal mine.展开更多
To enhance the explosion suppression effects of water mist, various potassium halide additives were tested in a confined vessel filled with a 10% mixture of methane/air. Air and CO2(0.7 MPa) were used as driver gases....To enhance the explosion suppression effects of water mist, various potassium halide additives were tested in a confined vessel filled with a 10% mixture of methane/air. Air and CO2(0.7 MPa) were used as driver gases. The results revealed that halide additives exhibit considerable suppression effects on explosion overpressure. A30% KI mist decreased the explosion overpressure by 27.46% compared with the suppression by pure water mist under the same conditions. When CO2 is used as the driver gas, it will dissolve in water under high pressure.The synergistic effect of a CO2 solution with an effective additive afforded significant suppression. Under the same conditions, the overpressures suppressed by a mist of 30% KI + 0.7 MPa CO2 solution decreased by 33.53% compared with those suppressed by pure water mist driven by air. The synergistic suppression effect is much better than that of a 0.7 MPa CO2 solution mist or 30% KI mist alone. The multicomponent additives can be considered when suppressing methane/air explosions with pressure-formed water mist.展开更多
In order to apply ultra-fine water mist technology on spontaneous coal combustion in the goaf of a coal mine, we built a small scale compartment with ultra-fine water mist for restraining coal combustion in a confined...In order to apply ultra-fine water mist technology on spontaneous coal combustion in the goaf of a coal mine, we built a small scale compartment with ultra-fine water mist for restraining coal combustion in a confined space and then investigated the restraining efficiency and related factors. The study obtained the following results: a descending rate of heat release, an increase in O2, the production of CO2 decreased gradually, while the production of CO increased dramatically and quickly and then decreased; ultimately it tended to become stable after the discharge of an ultra-fine water mist. The technology showed that the ultra-fine water mist can effectively reduce the heat release rate of coal and the rate to generate components. We found that the restraining effect relied on the mist flux, the discharge time and other factors. A sufficient amount of mist has a better effect compared to an insufficient amount of mist. To combat coal combustion, the greater the discharge time, the better coal flames are extinguished.展开更多
Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives...Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives are used to compare the firefighting performance of diesel and heptane fire in open space. By adjusting the concentration of substance in the additives and conducting the experiment under the pressure of 0.3 MPa,0.5 MPa and 0.7 MPa,extinguish time and temperature are measured in the experiment. Through the experiments using different fuels,it can be found when the fuel is heptane that has a lower ignition point and a higher evaporation rate, the water mist additive can still significantly improve the firefighting performance. According to the data based on different concentrations of fluorinated surfactants,we find that fluorinated surfactants are the main substance to improve the performances by changing physical property of water mist. Optimal proportion of the additives for firefighting performance is found by experiment results.展开更多
Okinawa in the subtropical islands enclosed in the ocean has a problem that corrosion of structures progresses quickly because of high temperature, high humidity and adhesion of sea-water mists flying from sea. Author...Okinawa in the subtropical islands enclosed in the ocean has a problem that corrosion of structures progresses quickly because of high temperature, high humidity and adhesion of sea-water mists flying from sea. Author is interested in corrosion of bridge made of weatherability steel. Therefore, it needs to investigate the flow structure around bridge beams and behavior of sea-water mist (droplet). In this paper, flow visualization and PIV are attempted to understand the flow structures around bridge beams and, furthermore, numerical approach of motion of droplets is attempted to understand the collision of sea-water mists on the bridge wall.展开更多
Interaction between water mist and fire smoke is studied by experiments in an ISO 9705 room, The variation of 02, CO and CO2 concentration is disclosed, and the mathematical models of smoke component con- centration w...Interaction between water mist and fire smoke is studied by experiments in an ISO 9705 room, The variation of 02, CO and CO2 concentration is disclosed, and the mathematical models of smoke component con- centration with water mist pressure and ventilation speed are established according to the experimental results. It is found in the experiment that the smoke component concentration will break when ventilation speed exceeds 1.5 kg/s. This paper provides necessary theory for water mist technology using in smoke restraining.展开更多
The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, s...The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, several operating factors were adjusted with the results of each adjustment subsequently measured. The operating factors studied included： operating pressures, foam concentrations, cabin opening issues, and obstacles. Each of the factors was compared with the others so as to find out which combinations would be most suitable for a water mist spray system installed inside a wind turbine cabin. The presence of obstructions hinders the direct impact of the mist spray on the fire source and in average an additional 2 to 3 minutes is required to put out the fire. This study found that the effect of the foam-water ratio is linear. Regardless of the scenario, the optimum mixture ratio is 3%. The line graph shows that the most unsuitable aqueous film-forming mixture ratio is 6%. This experiment found that the main fire extinguishing mechanism of water mist spray is the cooling of a large area via water droplets. This system is very effective in bringing down the temperature. The addition of foam in water mist spray, however, impaired the effectiveness of the cooling effect although the fire control mechanism via emulsification markedly reduced the time required to put out the fire. The increase in foam magnification will considerably enhance the fire extinguishing efficiency.展开更多
Located south of the West Bank, Wadi Al-Samen is considered one of the most important sources of groundwater recharge for the eastern aquifer in Hebron. It is polluted by sewage originating from domestic and industria...Located south of the West Bank, Wadi Al-Samen is considered one of the most important sources of groundwater recharge for the eastern aquifer in Hebron. It is polluted by sewage originating from domestic and industrial consumption in the Hebron area. Water quality assessment is an important criterion for achieving sustainable development. To evaluate water quality, twenty samples were collected from groundwater sources for two seasons and were analyzed for Physical properties (Total dissolved solids (TDS), Electrical conductivity (EC), potential hydrogen (pH), Temperature (T)), Four major cations (Mg<sup>2+</sup>, Ca<sup>2+</sup>, Na<sup>+</sup> and K<sup>+</sup>), and the Major anions (HCO<sup>-</sup>3</sub>, Cl<sup>-</sup>, and SO<sup>2-</sup>4</sub>);geochemical methods such as Piper scheme were used for the sample result analysis. To characterize wastewater components, six samples were collected from the Wadi discharge for two seasons and were analyzed (potential hydrogen (pH), Electrical Conductivity (EC), Total Dissolved Solid (TDS), Total Suspended Solids (TDS), Total Suspended Solids (TSS), Biological Oxygen Demand (BOD<sub>5</sub>), and Chemical Oxygen Demand (COD). The results of nitrate levels showed that 20% of the ground water samples exceeded the standard limit of the World Health Organization (WHO). The quality of drinking water was assessed using the Water Quality Index (WQI), which suggests that 10% of samples are classified from poor to very poor. The abundance of cations from highest to lowest was found to be: Ca;Mg;Na, and for the anions it is HCO<sub>3</sub>;Cl;SO<sub>4</sub>. The dominant hydrochemical facies of 35% of collected aquifer samples reveal that Ca-Mg-Na-Cl-HCO<sub>3</sub> are in the domain. Evaluation of irrigation suitability was performed using parameters of Sodium adsorption ratio (SAR), electric conductivity (EC), and Salinity. The results in both rounds for EC showed that all water sources are suitable for irrigation according to Todd’s classification. SAR was not suitable in three water resources samples. Wilcox analysis for the two seasons revealed that 85% of samples are not appropriate for irrigation uses.展开更多
Geological explorations have revealed plentiful Neogene formation waters in anticlines in the central Qaidam Basin(QB).However,the hydrochemistry and origin of these waters are obscure.In this study,the hydrochemistry...Geological explorations have revealed plentiful Neogene formation waters in anticlines in the central Qaidam Basin(QB).However,the hydrochemistry and origin of these waters are obscure.In this study,the hydrochemistry and DO-S-Sr isotopes of these formation waters were determined to study their origin and evolution.The formation waters are enriched in Na-Ca-Cl,and depleted in Mg-K-SO4-HCO3ions with elevated Li-B-Br-Sr elements.The D-O isotopes prove that the formation waters originated from weak-evaporated meteoric waters,and experienced water-rock interactions.Ion comparisons and Caexcess-Nadeficitdiagrams suggest that solute sources of these waters include evaporite dissolution,waterrock interaction,and minor residual lake brines.Bacterial sulfate reduction and water-rock interactions are supported by the high S-Sr isotopes.The enriched Li-B-Br-Sr concentrations of these waters are in accord with the high geochemical background values of the QB.Regarding the genesis of the formation waters,it can be concluded that meteoric waters from the southern Kunlun Mountains were discharged into the basin,weakly evaporated,and then infiltrated into the Neogene strata through faults leaching the soluble ions and mixing with residual lake brines,and all experienced water-rock interactions and a sulphate reduction process.展开更多
Oil and gas industries generate a significant amount of water during the production. The composition of this water varies with the geologic age, depth, and geochemistry of the region along with the chemicals added dur...Oil and gas industries generate a significant amount of water during the production. The composition of this water varies with the geologic age, depth, and geochemistry of the region along with the chemicals added during the process. Geochemistry of formation water is used for aquifer identification, pollution problems, water compatibility studies, corrosion monitoring, water-quality control, water flooding, exploration, and to diagnose wellbore integrity issues. The current study investigates the spatial and temporal variation of produced water geochemistry from one of the largest conventional oil field, Ghawar field, Saudi Arabia. Produced water from different wellheads were collected and analyzed for different geochemical characteristics. Sixteen wells from ABQQ, nineteen wells from ANDR and twenty wells from SDGM area were selected for the current study. Sampling and analysis were performed as per the standard procedures. Results indicated that the pH of the sample varied from 6.0 to 7.4, and Electrical conductivity from 94200 to 102690 μS/cm. The spatial variation of major cations and anions were also recorded and represented by graphical plots. Metal analysis indicated the highest concentration for boron, which is 20.5 mg/L at ABQQ area, whereas all other metals are very low in concentration. Temporal variation of a single well at SDGM area indicated drastic change in the ionic concentration, whereas the geochemistry remains same as indicated by Tickler plot. The water type of the respective area was studied by tickler plots, which indicated same source of formation water in different wells at ABQQ, ANDR and SDGM areas. The ionic concentration is also used to predict corrosion and scaling issues. By Langelier Saturation Index (LSI) and Ryznar Stability Index (RSI), the sample from all the wells showed higher scaling potential. The study concludes that the water type in different areas under Ghawar field remains same regardless of drastic changes in the ionic concentration, which can be used to diagnose wellbore integrity issues.展开更多
A multi-faceted Case Area Targeted Intervention (CATI) approach emphasizing the integration of Water, Sanitation and Hygiene (WASH) interventions and Oral Cholera Vaccine (OCV) campaign was employed to respond to the ...A multi-faceted Case Area Targeted Intervention (CATI) approach emphasizing the integration of Water, Sanitation and Hygiene (WASH) interventions and Oral Cholera Vaccine (OCV) campaign was employed to respond to the outbreak of cholera in Garissa County. Drinking water sources in areas heavily impacted by cholera were systematically mapped and tested for microbiological quality. The quality assessment was carried out in April 2023 during an ongoing cholera outbreak in the county. A total of 109 samples were collected and tested for thermotolerant coliforms and other in situ parameters. The finding revealed that more than 87% of the samples did not meet the World Health Organization (WHO) standard for thermotolerant coliforms;and 30% had turbidity values above the recommended threshold values. None of the 109 samples had any traceable residual chlorine. Following these findings, the county government implemented the targeted interventions which resulted in a positive impact in the fight against cholera. The WHO supported key interventions which included capacity building in water quality monitoring and prepositioning of critical WASH commodities to the cholera affected areas.展开更多
The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the coll...The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the collection of wastewater samples. Their analysis revealed specific pollutant loads, including loads of BOD5 3.6966 kgO<sub>2</sub>/day and COD of 12.8775 kgO<sub>2</sub>/day, which were central to the design phase. Following a rigorous assessment of the existing sanitation infrastructure, constructed wetland (CWs) emerged as the most appropriate ecological solution. This system, valued for its ability to effectively remove contaminants, was tailored to the specific needs of the site. Consequently, the final design of the filter extends over 217.16 m<sup>2</sup>, divided into two cells of 108.58 m<sup>2</sup> each, with dimensions of 12.77 m in length and 8.5 m in width. The depth of the filtering medium is approximately 0.60 m, meeting the standards while ensuring maximized purification. Typha, an indigenous and prolific plant known for its purification abilities, was selected as the filtering agent. Concurrently, non-crushed gravel was chosen for its proven filtration capacity. This study is the result of a combination of scientific rigor and design expertise. It provides a holistic view of sanitation for Ndiebene Gandiol. The technical specifications and dimensions of the constructed wetland filter embody an approach that marries indepth analysis and practical application, all aimed at delivering an effective and long-lasting solution to the local sanitation challenges. By integrating precise scientific data with sanitation design expertise, this study delivers a holistic solution for Ndiebene Gandiol. The detailed dimensions and specifications of the constructed wetland filter reflect a methodology that combines meticulous analysis with practical adaptation, aiming to provide an effective and sustainable response to the challenges of rural and school sanitation in the northern region of Senegal.展开更多
Hydraulic fracturing facilitates the development and exploitation of unconventional reservoirs.In this study,the injected hydraulic fracturing fluid(HFF)and flowback and produced water(FPW)in tight oil reservoirs of t...Hydraulic fracturing facilitates the development and exploitation of unconventional reservoirs.In this study,the injected hydraulic fracturing fluid(HFF)and flowback and produced water(FPW)in tight oil reservoirs of the Lucaogou Formation in the Junggar Basin are temporally sampled from day 1 to day 64.Freshwater is used for fracturing,and HFF is obtained.The chemical and isotopic parameters(including the water type,total salinity,total dissolved solids(TDS),pH,concentrations of Na^(+),Cl^(-),Ba^(+),K^(+),Fe^(2+)+Fe^(3+),and CO_(3)^(2-),dD,and δ^(18)O)are experimentally obtained,and their variations with time are systematically analyzed based on the flowback water.The results show that the water type,Na/Cl ratio,total salinity,and TDS of the FPW change periodically primarily due to the HFF mixing with formation water,thus causing δD and δ^(18)O to deviate from the meteoric water line of Xinjiang.Because of watererock interaction(WRI),the concentrations of Fe^(2+)+Fe^(3+)and CO_(3)^(2-)of the FPW increase over time,with the solution pH becoming more alkaline.Furthermore,based on the significant changes observed in the geochemistry of the FPW,three separate time intervals of flowback time are identified:Stage Ⅰ(<10 days),where the FPW is dominated by the HFF and the changes in ions and isotopes are mainly caused by the WRI;Stage Ⅱ(10-37 days),where the FPW is dominated by the addition of formation water to the HFF and the WRI is weakened;and finally,Stage Ⅲ(>37 days),where the FPW is dominated by the chemistry of the formation water.The methodology implemented in this study can provide critical support for the source identification of formation water.展开更多
The knowledge of the residence time of formation water is fundamental to understanding the subsurface flow and hydrological setting.To better identify the origin and evolution of coal seam water and its impact on gas ...The knowledge of the residence time of formation water is fundamental to understanding the subsurface flow and hydrological setting.To better identify the origin and evolution of coal seam water and its impact on gas storage and production,this study collected coalbed methane co-produced water in the southeast Qinshui Basin and detected chemical and isotopic compositions,especially 36Cl and 129I concentrations.The calculated tracer ages of 129I(5.2–50.6 Ma)and 36Cl(0.13–0.76 Ma)are significantly younger than the age of coal-bearing formation(Pennsylvanian-Cisuralian),indicating freshwater recharge after coal deposition.The model that utilises 129I/I and 36Cl/Cl ratios to constrain the timing of recharge and the proportion of recharge water reveals that over 60%of pre-anthropogenic meteoric water entered coal seams since 10 Ma and mixed with residue initial deposition water,corresponding to the basin inversion in Cenozoic.The spatial distribution of major ion concentrations reveals the primary recharge pathway for meteoric water from coal outcrops at the eastern margin to the basin center.This study demonstrates the occurrence of higher gas production rates from wells that accept water recharge in recent times and suggests the possible potential of the non-stagnant zones for high gas production.展开更多
文摘BACKGROUND This case of gestational gingival tumor is huge and extremely rare in clinical practice.As the growth location of this gingival tumor is in the upper anterior tooth area,it seriously affects the pregnant woman's speech and food,causing great pain to the patient.The use of Nd:YGA water mist laser to remove the gingival tumor resulted in minimal intraoperative bleeding,minimal adverse reactions,and good postoperative healing,which is worthy of clinical promotion and application.CASE SUMMARY The patient,a pregnant woman,reported a large lump in her mouth on the first day of postpartum treatment.Based on medical history and clinical examination,the diagnosis was diagnosed as gestational gingival tumor.Postoperative pathological biopsy also confirmed this diagnosis.The use of Nd:YAG water mist laser to remove the tumor resulted in minimal intraoperative bleeding,clear surgical field of view,short surgical time,and good postoperative healing.CONCLUSION In comparison to traditional surgery,Nd:YAG water mist laser surgery is minimally invasive,minimizes cell damage,reduces bleeding,ensures a clear field of vision,and virtually eliminates postoperative edema,carbonization,and the risk of cross infection.It has unique advantages in oral soft tissue surgery for pregnant patients.Therefore,the clinical application of Nd:YAG water mist laser for the treatment of gestational gingival tumors is an ideal choice.
基金supported by Science and Technology Projects Funded by State Grid Corporation of China (5200202024105A0000).
文摘To thoroughly study the extinguishing effect of a high-pressure water mist fire extinguishing system when a transformer fire occurs,a 3D experimental model of a transformer is established in this work by employing Fire Dynamics Simulator(FDS)software.More specifically,by setting different parameters,the process of the highpressure water mist fire extinguishing system with the presence of both diverse ambient temperatures and water mist sprinkler laying conditions is simulated.In addition,the fire extinguishing effect of the employed high-pressure water mist system with the implementation of different strategies is systematically analyzed.The extracted results show that a fire source farther away fromthe centerline leads to a lower local temperature distribution.In addition,as the ambient temperature increases,the temperature above the fire source decreases,while the temperature and the concentrationof theupperflue gas layer bothdecrease.Interestingly,after thehigh-pressurewatermist sprinkler begins to operate,both the temperature distribution above the fire source and the concentration of the flue gas decrease,which indicates that the high-pressure water mist system plays the role of cooling and dust removal.By comparing various sprinkler laying methods,it is found that the lower sprinkler height has a better effect on the temperature above the fire source,the temperature of the upper flue gas layer,and the concentration of the flue gas.Moreover,when the sprinkler is spread over thewhole transformer,the cooling effect on both the temperature above the fire source and the temperature of the upper flue gas layer is good,whereas the change in the concentration of the flue gas above the fire source is not obvious compared to the case where the sprinkler is not fully spread.
基金financial supports of the National Key Research and Development Program of China(2018YFC0808103)the National Natural Science Foundation of China (51774115, 51604095)。
文摘Combined effects of obstacles and fine water mist on a methane-air explosion of a semi-closed pipe were investigated experimentally.In this study,the diameter of the water mist,the location,and the number of obstacles was considered.The results demonstrated that 5 μm water mist present a significant suppression affected while 45 μm shows a slight promotion effected on a gas explosion of the condition without obstacles.In the presence of an obstacle,however,the inhibitory effect of 5 μm water veils of mist dropped significantly during flame propagation,and the effect of 45 μm water veils of mist changed from the enhancement of inhibition,and its inhibitory effect was significant.The inhibitory effect of 45 μm water veils of mist on gas explosion weakened firstly and then enhanced with the increasing distance between obstacle location from the ignition location as well as in several obstacles.
基金This work was supported by Science and Technology Project Funded by State Grid Henan Electric Power Company(521702200004)Henan Province Key R&D and Promotion Special(Technology Research)Project(212102210016)Opening Fund of State Key Laboratory of Fire Science(SKLFS)under Grant No.HZ2021-KF11.
文摘In order to study the extinguishing performance of high-pressure-water-mist-based systems on the fires originating from power transformers the PyroSim software is used.Different particle velocities and flow rates are considered.The evolution laws of temperature around transformer,flue gas concentration and upper layer temperature of flue gas are analyzed under different boundary conditions.It is shown that the higher the particle velocity is,the lower the smoke concentration is,the better the cooling effect on the upper layer temperature of flue gas layer is,the larger the flow rate is and the better the cooling effect is.
文摘The effects of a fine water mist environment in a semi-confined blast chamber on the chemical and thermodynamic processes following detonation of a 20 g PE4 explosive charge have been investigated.The effects were quantified by the analysis of pressure profiles recorded where several parameters including arrival time of the shock at the sensors, peak overpressures, specific impulse of the positive phase, period of the negative phase and the specific impulse of the multiple reflections were quantified.The effect of the fine water mist on the arrival time, peak pressures and the specific impulse of the positive phase agrees with previous findings in literature. In this paper, the focus is on the implications of the fine water mist on the negative phase and the impulse of multiple pressure reflections. The period of the negative phase was found to have increased by 40% and with higher negative peak pressure in the mist condition compared to the atmospheric condition. The activities of the multiple pressure reflections were found to have decreased considerably, both in number and in amplitude leading to lower impulses(by about 60%) for the water mist conditions.
基金Supported by the Natural Science Foundation of China(50274061,50476033)The Outstanding Talents Innovative Foundation of Henan Province of China(421000800)the Natural Science Foundation of HPU(646102)
文摘The main objective of the present study was introduced water mist suppressiontechnology to prevent and control gas burning which occurred during drilling at Wu20160working-face in No.10 coal mine of Pingdingshan Ltd..Based on the self-developed ex-periment platform,a series of fire suppression tests to evaluate the performance of a watermist system were conducted.The detailed measurements of the spray characteristics,i.e.,the Sauter Mean Diameter(SMD),the velocity and spray angle which are the main pa-rameters considered in the Study,were obtained by using LS-2000 Sizer.The amount ofwater consumed and the water flux density distribution over the cross section downstreamthe nozzle exit were measured by cup collector method.The operating pressure of thewater mist nozzle is set to 0.5 MPa,the droplet SMD of 104 pm,the water flux density dis-tribution from 0.71 to 8.47 L/(m^2.min),the average velocity of 2.14 m/s.The experimentalresults show that the averaged time required for extinguishment is 3.14 s,and the corre-sponding amount of water used during fire test is about 0.11 kg.The gas fire suppressionsystem reduces the temperature in combustion chamber of the experimental apparatusbelow the ignition point of the gas,which can effectively avoid the occurrence of the gasfire in coal mine.
基金Supported by the Key Technologies R&D Program of Tianjin(15ZCZDSF00550)the“Strengthen Police Force by Science and Technology” Special Foundation on Basic Research of Ministry of Public Security(2015GABJC28)the Key Technical Research Plan of Ministry of Public Security(2017JSYJA13).
文摘To enhance the explosion suppression effects of water mist, various potassium halide additives were tested in a confined vessel filled with a 10% mixture of methane/air. Air and CO2(0.7 MPa) were used as driver gases. The results revealed that halide additives exhibit considerable suppression effects on explosion overpressure. A30% KI mist decreased the explosion overpressure by 27.46% compared with the suppression by pure water mist under the same conditions. When CO2 is used as the driver gas, it will dissolve in water under high pressure.The synergistic effect of a CO2 solution with an effective additive afforded significant suppression. Under the same conditions, the overpressures suppressed by a mist of 30% KI + 0.7 MPa CO2 solution decreased by 33.53% compared with those suppressed by pure water mist driven by air. The synergistic suppression effect is much better than that of a 0.7 MPa CO2 solution mist or 30% KI mist alone. The multicomponent additives can be considered when suppressing methane/air explosions with pressure-formed water mist.
基金Project 50274061 supported by the National Natural Science Foundation of Chinaprovided by the NSFC (50274061)+3 种基金the Program for Changjiang Scholars and Innovative Research Team in University (IRT0618)the Henan Province Basic and Lead-ing-edge Technology Research Program (082300 463205 and 072300420180)the Program for New Century Excellent Talents in University of Henan Province (2005HANCET-05) the Henan Poly-technic University Innovation Funds of Graduate Student Scientific Dissertation (M-20) is gratefully acknowledged
文摘In order to apply ultra-fine water mist technology on spontaneous coal combustion in the goaf of a coal mine, we built a small scale compartment with ultra-fine water mist for restraining coal combustion in a confined space and then investigated the restraining efficiency and related factors. The study obtained the following results: a descending rate of heat release, an increase in O2, the production of CO2 decreased gradually, while the production of CO increased dramatically and quickly and then decreased; ultimately it tended to become stable after the discharge of an ultra-fine water mist. The technology showed that the ultra-fine water mist can effectively reduce the heat release rate of coal and the rate to generate components. We found that the restraining effect relied on the mist flux, the discharge time and other factors. A sufficient amount of mist has a better effect compared to an insufficient amount of mist. To combat coal combustion, the greater the discharge time, the better coal flames are extinguished.
基金Opening Fund of State Key Laboratory of Fire Science,University of Science and Technology of China(No.HZ2011-KF04)
文摘Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives are used to compare the firefighting performance of diesel and heptane fire in open space. By adjusting the concentration of substance in the additives and conducting the experiment under the pressure of 0.3 MPa,0.5 MPa and 0.7 MPa,extinguish time and temperature are measured in the experiment. Through the experiments using different fuels,it can be found when the fuel is heptane that has a lower ignition point and a higher evaporation rate, the water mist additive can still significantly improve the firefighting performance. According to the data based on different concentrations of fluorinated surfactants,we find that fluorinated surfactants are the main substance to improve the performances by changing physical property of water mist. Optimal proportion of the additives for firefighting performance is found by experiment results.
文摘Okinawa in the subtropical islands enclosed in the ocean has a problem that corrosion of structures progresses quickly because of high temperature, high humidity and adhesion of sea-water mists flying from sea. Author is interested in corrosion of bridge made of weatherability steel. Therefore, it needs to investigate the flow structure around bridge beams and behavior of sea-water mist (droplet). In this paper, flow visualization and PIV are attempted to understand the flow structures around bridge beams and, furthermore, numerical approach of motion of droplets is attempted to understand the collision of sea-water mists on the bridge wall.
基金National Natural Science Foundation Youth Science Foundation (No.50904041)China Postdoctoral Science Foundation (No.20070410067)
文摘Interaction between water mist and fire smoke is studied by experiments in an ISO 9705 room, The variation of 02, CO and CO2 concentration is disclosed, and the mathematical models of smoke component con- centration with water mist pressure and ventilation speed are established according to the experimental results. It is found in the experiment that the smoke component concentration will break when ventilation speed exceeds 1.5 kg/s. This paper provides necessary theory for water mist technology using in smoke restraining.
文摘The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, several operating factors were adjusted with the results of each adjustment subsequently measured. The operating factors studied included： operating pressures, foam concentrations, cabin opening issues, and obstacles. Each of the factors was compared with the others so as to find out which combinations would be most suitable for a water mist spray system installed inside a wind turbine cabin. The presence of obstructions hinders the direct impact of the mist spray on the fire source and in average an additional 2 to 3 minutes is required to put out the fire. This study found that the effect of the foam-water ratio is linear. Regardless of the scenario, the optimum mixture ratio is 3%. The line graph shows that the most unsuitable aqueous film-forming mixture ratio is 6%. This experiment found that the main fire extinguishing mechanism of water mist spray is the cooling of a large area via water droplets. This system is very effective in bringing down the temperature. The addition of foam in water mist spray, however, impaired the effectiveness of the cooling effect although the fire control mechanism via emulsification markedly reduced the time required to put out the fire. The increase in foam magnification will considerably enhance the fire extinguishing efficiency.
文摘Located south of the West Bank, Wadi Al-Samen is considered one of the most important sources of groundwater recharge for the eastern aquifer in Hebron. It is polluted by sewage originating from domestic and industrial consumption in the Hebron area. Water quality assessment is an important criterion for achieving sustainable development. To evaluate water quality, twenty samples were collected from groundwater sources for two seasons and were analyzed for Physical properties (Total dissolved solids (TDS), Electrical conductivity (EC), potential hydrogen (pH), Temperature (T)), Four major cations (Mg<sup>2+</sup>, Ca<sup>2+</sup>, Na<sup>+</sup> and K<sup>+</sup>), and the Major anions (HCO<sup>-</sup>3</sub>, Cl<sup>-</sup>, and SO<sup>2-</sup>4</sub>);geochemical methods such as Piper scheme were used for the sample result analysis. To characterize wastewater components, six samples were collected from the Wadi discharge for two seasons and were analyzed (potential hydrogen (pH), Electrical Conductivity (EC), Total Dissolved Solid (TDS), Total Suspended Solids (TDS), Total Suspended Solids (TSS), Biological Oxygen Demand (BOD<sub>5</sub>), and Chemical Oxygen Demand (COD). The results of nitrate levels showed that 20% of the ground water samples exceeded the standard limit of the World Health Organization (WHO). The quality of drinking water was assessed using the Water Quality Index (WQI), which suggests that 10% of samples are classified from poor to very poor. The abundance of cations from highest to lowest was found to be: Ca;Mg;Na, and for the anions it is HCO<sub>3</sub>;Cl;SO<sub>4</sub>. The dominant hydrochemical facies of 35% of collected aquifer samples reveal that Ca-Mg-Na-Cl-HCO<sub>3</sub> are in the domain. Evaluation of irrigation suitability was performed using parameters of Sodium adsorption ratio (SAR), electric conductivity (EC), and Salinity. The results in both rounds for EC showed that all water sources are suitable for irrigation according to Todd’s classification. SAR was not suitable in three water resources samples. Wilcox analysis for the two seasons revealed that 85% of samples are not appropriate for irrigation uses.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,Grant No.2019QZKK0805)the Special Project of Qinghai Scholars(Grant No.QHS201802)+1 种基金National Natural Science Foundation of China(NSFC,Grant Nos.41872093,U21A2018)Foundation of Qinghai Science&Technology Department(Grant No.2021-ZJ-932)。
文摘Geological explorations have revealed plentiful Neogene formation waters in anticlines in the central Qaidam Basin(QB).However,the hydrochemistry and origin of these waters are obscure.In this study,the hydrochemistry and DO-S-Sr isotopes of these formation waters were determined to study their origin and evolution.The formation waters are enriched in Na-Ca-Cl,and depleted in Mg-K-SO4-HCO3ions with elevated Li-B-Br-Sr elements.The D-O isotopes prove that the formation waters originated from weak-evaporated meteoric waters,and experienced water-rock interactions.Ion comparisons and Caexcess-Nadeficitdiagrams suggest that solute sources of these waters include evaporite dissolution,waterrock interaction,and minor residual lake brines.Bacterial sulfate reduction and water-rock interactions are supported by the high S-Sr isotopes.The enriched Li-B-Br-Sr concentrations of these waters are in accord with the high geochemical background values of the QB.Regarding the genesis of the formation waters,it can be concluded that meteoric waters from the southern Kunlun Mountains were discharged into the basin,weakly evaporated,and then infiltrated into the Neogene strata through faults leaching the soluble ions and mixing with residual lake brines,and all experienced water-rock interactions and a sulphate reduction process.
文摘Oil and gas industries generate a significant amount of water during the production. The composition of this water varies with the geologic age, depth, and geochemistry of the region along with the chemicals added during the process. Geochemistry of formation water is used for aquifer identification, pollution problems, water compatibility studies, corrosion monitoring, water-quality control, water flooding, exploration, and to diagnose wellbore integrity issues. The current study investigates the spatial and temporal variation of produced water geochemistry from one of the largest conventional oil field, Ghawar field, Saudi Arabia. Produced water from different wellheads were collected and analyzed for different geochemical characteristics. Sixteen wells from ABQQ, nineteen wells from ANDR and twenty wells from SDGM area were selected for the current study. Sampling and analysis were performed as per the standard procedures. Results indicated that the pH of the sample varied from 6.0 to 7.4, and Electrical conductivity from 94200 to 102690 μS/cm. The spatial variation of major cations and anions were also recorded and represented by graphical plots. Metal analysis indicated the highest concentration for boron, which is 20.5 mg/L at ABQQ area, whereas all other metals are very low in concentration. Temporal variation of a single well at SDGM area indicated drastic change in the ionic concentration, whereas the geochemistry remains same as indicated by Tickler plot. The water type of the respective area was studied by tickler plots, which indicated same source of formation water in different wells at ABQQ, ANDR and SDGM areas. The ionic concentration is also used to predict corrosion and scaling issues. By Langelier Saturation Index (LSI) and Ryznar Stability Index (RSI), the sample from all the wells showed higher scaling potential. The study concludes that the water type in different areas under Ghawar field remains same regardless of drastic changes in the ionic concentration, which can be used to diagnose wellbore integrity issues.
文摘A multi-faceted Case Area Targeted Intervention (CATI) approach emphasizing the integration of Water, Sanitation and Hygiene (WASH) interventions and Oral Cholera Vaccine (OCV) campaign was employed to respond to the outbreak of cholera in Garissa County. Drinking water sources in areas heavily impacted by cholera were systematically mapped and tested for microbiological quality. The quality assessment was carried out in April 2023 during an ongoing cholera outbreak in the county. A total of 109 samples were collected and tested for thermotolerant coliforms and other in situ parameters. The finding revealed that more than 87% of the samples did not meet the World Health Organization (WHO) standard for thermotolerant coliforms;and 30% had turbidity values above the recommended threshold values. None of the 109 samples had any traceable residual chlorine. Following these findings, the county government implemented the targeted interventions which resulted in a positive impact in the fight against cholera. The WHO supported key interventions which included capacity building in water quality monitoring and prepositioning of critical WASH commodities to the cholera affected areas.
文摘The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the collection of wastewater samples. Their analysis revealed specific pollutant loads, including loads of BOD5 3.6966 kgO<sub>2</sub>/day and COD of 12.8775 kgO<sub>2</sub>/day, which were central to the design phase. Following a rigorous assessment of the existing sanitation infrastructure, constructed wetland (CWs) emerged as the most appropriate ecological solution. This system, valued for its ability to effectively remove contaminants, was tailored to the specific needs of the site. Consequently, the final design of the filter extends over 217.16 m<sup>2</sup>, divided into two cells of 108.58 m<sup>2</sup> each, with dimensions of 12.77 m in length and 8.5 m in width. The depth of the filtering medium is approximately 0.60 m, meeting the standards while ensuring maximized purification. Typha, an indigenous and prolific plant known for its purification abilities, was selected as the filtering agent. Concurrently, non-crushed gravel was chosen for its proven filtration capacity. This study is the result of a combination of scientific rigor and design expertise. It provides a holistic view of sanitation for Ndiebene Gandiol. The technical specifications and dimensions of the constructed wetland filter embody an approach that marries indepth analysis and practical application, all aimed at delivering an effective and long-lasting solution to the local sanitation challenges. By integrating precise scientific data with sanitation design expertise, this study delivers a holistic solution for Ndiebene Gandiol. The detailed dimensions and specifications of the constructed wetland filter reflect a methodology that combines meticulous analysis with practical adaptation, aiming to provide an effective and sustainable response to the challenges of rural and school sanitation in the northern region of Senegal.
基金supported by the National Natural Science Foundation of China(No.U2003102).
文摘Hydraulic fracturing facilitates the development and exploitation of unconventional reservoirs.In this study,the injected hydraulic fracturing fluid(HFF)and flowback and produced water(FPW)in tight oil reservoirs of the Lucaogou Formation in the Junggar Basin are temporally sampled from day 1 to day 64.Freshwater is used for fracturing,and HFF is obtained.The chemical and isotopic parameters(including the water type,total salinity,total dissolved solids(TDS),pH,concentrations of Na^(+),Cl^(-),Ba^(+),K^(+),Fe^(2+)+Fe^(3+),and CO_(3)^(2-),dD,and δ^(18)O)are experimentally obtained,and their variations with time are systematically analyzed based on the flowback water.The results show that the water type,Na/Cl ratio,total salinity,and TDS of the FPW change periodically primarily due to the HFF mixing with formation water,thus causing δD and δ^(18)O to deviate from the meteoric water line of Xinjiang.Because of watererock interaction(WRI),the concentrations of Fe^(2+)+Fe^(3+)and CO_(3)^(2-)of the FPW increase over time,with the solution pH becoming more alkaline.Furthermore,based on the significant changes observed in the geochemistry of the FPW,three separate time intervals of flowback time are identified:Stage Ⅰ(<10 days),where the FPW is dominated by the HFF and the changes in ions and isotopes are mainly caused by the WRI;Stage Ⅱ(10-37 days),where the FPW is dominated by the addition of formation water to the HFF and the WRI is weakened;and finally,Stage Ⅲ(>37 days),where the FPW is dominated by the chemistry of the formation water.The methodology implemented in this study can provide critical support for the source identification of formation water.
基金supported by the National Natural Science Foundation of China(Grant Nos.42150710532 and 42103048).
文摘The knowledge of the residence time of formation water is fundamental to understanding the subsurface flow and hydrological setting.To better identify the origin and evolution of coal seam water and its impact on gas storage and production,this study collected coalbed methane co-produced water in the southeast Qinshui Basin and detected chemical and isotopic compositions,especially 36Cl and 129I concentrations.The calculated tracer ages of 129I(5.2–50.6 Ma)and 36Cl(0.13–0.76 Ma)are significantly younger than the age of coal-bearing formation(Pennsylvanian-Cisuralian),indicating freshwater recharge after coal deposition.The model that utilises 129I/I and 36Cl/Cl ratios to constrain the timing of recharge and the proportion of recharge water reveals that over 60%of pre-anthropogenic meteoric water entered coal seams since 10 Ma and mixed with residue initial deposition water,corresponding to the basin inversion in Cenozoic.The spatial distribution of major ion concentrations reveals the primary recharge pathway for meteoric water from coal outcrops at the eastern margin to the basin center.This study demonstrates the occurrence of higher gas production rates from wells that accept water recharge in recent times and suggests the possible potential of the non-stagnant zones for high gas production.
