In order to study the problems of unreasonable airflow distribution and serious dust pollution in a heading surface,an experimental platform for forced ventilation and dust removal was built based on the similar princ...In order to study the problems of unreasonable airflow distribution and serious dust pollution in a heading surface,an experimental platform for forced ventilation and dust removal was built based on the similar principles.Through the similar experiment and numerical simulation,the distribution of airflow field in the roadway and the spatial and temporal evolution of dust pollution under the conditions of forced ventilation were determined.The airflow field in the roadway can be divided into three zones:jet zone,vortex zone and reflux zone.The dust concentration gradually decreases from the head to the rear of the roadway.Under the forced ventilation conditions,there is a unilateral accumulation of dust,with higher dust concentrations away from the ducts.The position of the equipment has an interception effect on the dust.The maximum error between the test value and the simulation result is 12.9%,which verifies the accuracy of the experimental results.The research results can provide theoretical guidance for the application of dust removal technology in coal mine.展开更多
Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, mo...Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index （GI）, were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.展开更多
In order to reveal the influence of forced ventilation on the dispersion of droplets ejected from roadheader-mounted external sprayer,the paper studies the air-flowing field and the droplet distribution under the cond...In order to reveal the influence of forced ventilation on the dispersion of droplets ejected from roadheader-mounted external sprayer,the paper studies the air-flowing field and the droplet distribution under the condition of gentle breeze and normal forced ventilation in heading face using the particle tracking technology of computational fluid dynamics(CFD).The results show that air-flowing tendency in the same section presents great comparability in the period of gentle breeze and forced ventilation,and the difference mainly embodies in the different wind velocity.The influence of ventilation on the dispersion of droplets is faint under the gentle breeze condition.The droplet can be evenly distributed around the cutting head.However,under the normal forced ventilation,a large number of droplets will drift to the return air side.At the same time,droplet clusters are predominantly presented in the lower part of windward side and the middle of the leeward side around the cutting head.In contrast,the droplet concentration in other parts around cutting head decreases a lot and the droplets are unable to form close-grained mist curtain.So the dust escape channel is formed.In addition,the simulation results also reveal that the disturbance of air flow on the droplet distribution can be effectively relieved when using ventilation duct with Coanda effect(VDCE).Field experiment results show that the dust suppression efficiency of total dust and respirable dust increases respectively by 10.5%and 9.3%when using VDCE,which proves that it can weaken the influence of airflow on droplet dispersion.展开更多
Forced ventilation is typically used in the construction of tunnels since it is an economical method to provide high amounts of fresh air.Air velocity and pollutant concentration near the work face are determined by t...Forced ventilation is typically used in the construction of tunnels since it is an economical method to provide high amounts of fresh air.Air velocity and pollutant concentration near the work face are determined by the ventilation arrangement.In the study,field measurement of air velocity was performed,and computational fluid dynamics(CFD)models were constructed to investigate airflow near the work face and predict the gas distribution in a gas tunnel construction.The effects of the distance between the air duct exit and the work face(L_(1))were evaluated by analyzing the flow field and pollutant concentration.The evaluation shows that the ventilation efficiency improves if L_(1) does not exceed 15 m in a road tunnel with full-face excavation.With respect to a road tunnel with benching excavation,the effects of bench length(L_(2))are analyzed,and the results of the analysis indicate that ventilation efficiency is optimal when L_(2)=5 m and L_(2)=10 m and the air-duct diameter corresponds to 1.6 m.The CFD results fit the field measurement significantly well,and the current ventilation system in the construction exhibits a relatively high efficiency.The findings of the study aid practitioners in optimizing ventilation efficiency.展开更多
Pigs are subjected to intensive environment control and management for higher productivity due to their sensitivity to climatic variation, which affects their growth. The aim of the current work is to numerically mode...Pigs are subjected to intensive environment control and management for higher productivity due to their sensitivity to climatic variation, which affects their growth. The aim of the current work is to numerically model the air speed and temperature in a forced ventilation piggery to achieve optimum environmental control. This work can also help to identify problems in the design of piggeries and offer suggestions for improvements. A steady two-dimensional numerical model including the effect of buoyancy, turbulence and heat generated by the pigs was solved using the computational fluid dynamics software Fluent, using the integral volume method. Air speed and temperature inside the piggery and at the pigs level were predicted for three different locations of ventilation opening, inlet velocities in the range (0.3 - 7 m/s), insulation or no insulation in the external walls, and for 5 ℃ and 32℃ ambient temperatures.展开更多
Pigs are subjected to intensive environment control and management in order to achieve higher productivity.This is due to their sensitivity to climatic variation,which strongly affects their growth.This paper reports ...Pigs are subjected to intensive environment control and management in order to achieve higher productivity.This is due to their sensitivity to climatic variation,which strongly affects their growth.This paper reports the design optimization of a forced ventilation piggery using computational fl uid dynamics.This numerical investigation determined the effect of varying the number of ventilation openings and their location on the air fl ow pattern,speed,temperature,power needed,ability to remove heat and residence time.The effect of varying the ventilation rate in a range(0.05–0.8 m3/s),and ambient temperatures of 5°C and 32°C was also investigated.The modeled piggery has dimensions 40 m×15 m×2.6 m,with central walkway and gable roof with the apex at 3.9 m and is a common design in Australia.A steady-state two-dimensional numerical model based on the integral volume method,including the effects of buoyancy and heat generated by the pigs,was solved using the computational fl uid dynamics software“Fluent.”Four designs were investigated and an optimum design,which facilitates better ventilation of the majority of the room,has been identifi ed.In summer,an inlet velocity has been recommended which achieves optimum environment inside the piggery meeting the pigs’thermal comfort criteria with minimum power usage.During winter it became obvious that heating has to be used in all designs to be able to meet the pigs’thermal comfort criteria.展开更多
Extraction of a coal seam which lies not far below a heating goafcan be a major safety challenge. A force auxiliary ventilation system was adopted as a control method in successful extraction and recovery of the panel...Extraction of a coal seam which lies not far below a heating goafcan be a major safety challenge. A force auxiliary ventilation system was adopted as a control method in successful extraction and recovery of the panel 30110 of the #3-1 coal seam, which is about 30-40 rn below the heating goaf of the #2-2 seam at Longhua underground coal mine, Shanxi Province, China. Booster fans and ventilation control devices such as doors and regulators were used in the system. The results show that, provided that a force auxiliary ventilation system is properly designed to achieve a pressure balance between a panel and its overlying goat＇, the system can be used to extract a coal seam overlain by a heating goal. This paper describes the design, installation and performance of the ventilation system during the extraction and recovery phases of the oanel 30110.展开更多
Performance of Photovoltaic-double skin façade(Photovoltaic-DSF)system in summer has been critical.Owing to high solar ingress,cooling requirement of a building significantly increases.Photovoltaic-DSF system pro...Performance of Photovoltaic-double skin façade(Photovoltaic-DSF)system in summer has been critical.Owing to high solar ingress,cooling requirement of a building significantly increases.Photovoltaic-DSF system provides a shield and controls the heat gain through fenestration in the interior spaces.In the present article,mathematical correlations are developed for energy characterization of forced-ventilated Photovoltaic-DSF system in India’s hot summer zone i.e.Jaipur.The Photovoltaic-DSF system has been installed and monitored for Jaipur’s summer months(May to July).L25 Orthogonal array of design parameters(air cavity thickness,air velocity,and PV panel’s transparency)and their respective levels have been developed using Taguchi design to perform experiments.Based on experimental results,multiple linear regression has been used to forecast solar heat gain coefficient,PVs electrical power and daylighting illuminance indoors as function of design factors.The statistical significance of mathematical relationships is sorted by variance analysis,which is found to be in good accord with field measurements(R2>0.90).The proposed correlations are pragmatic in designing Photovoltaic-DSF systems for hot summer conditions.The Photovoltaic-DSF system with 30%transmittance and air velocity of 5 metres per second in 200 mm air cavity thickness achieved maximum energy performance in hot summers.展开更多
In industrial scenarios,nanoparticles are incidentally generated in high concentrations during diverse material transformation processes,presenting potential health hazards for exposed workers.Consequently,as an indoo...In industrial scenarios,nanoparticles are incidentally generated in high concentrations during diverse material transformation processes,presenting potential health hazards for exposed workers.Consequently,as an indoor air quality management measure,their concentration is commonly reduced through localized forced ventilation.However,the control of these systems usually relies on traditional rule-based algorithms,which cannot deploy efficient control strategies such as model predictive control.To solve this issue,we propose a novel grey-box reduced order model method,never used before for industrial indoor nanoparticles.This approach can be deployed in model predictive control algorithms in buildings and does not present the data-reliance and transferability issues of black-box modeling.To test this model,a data collection campaign was conducted under real-world operating conditions in an industrial-scale thermal spraying booth,aiming to test the method’s viability for model calibration and validation of indoor total nanoparticle concentration through the maximum likelihood method,statistical validation tests,and physical viability assessment.Results for three different lumped sum models illustrate the effectiveness of grey-box modeling in industrial scenarios with confined processes and forced ventilation systems,handling observations’noise and background concentration fluctuations,and allowing a performance comparison between models.Further research could be conducted to study the viability of indoor total nanoparticle concentration reduced order models with higher spatial resolution,non-confined sources,and natural airflows.展开更多
Metro systems play a crucial role in enhancing the urban economy,but the serious dust pollution during its construction poses a significant threat to the health of workers.Widely used for dust control in metro systems...Metro systems play a crucial role in enhancing the urban economy,but the serious dust pollution during its construction poses a significant threat to the health of workers.Widely used for dust control in metro systems,the current forced ventilation technology is characterized by low dust control efficiency.In this study,an innovative arc device with efficient dust control and convenient application was proposed based on the forced ventilation.Subsequently,the orthogonal experimental method was adopted to explore the effects of air supply outlet position(L),air supply volume(Q),and air supply mode(M)on the airflow-dust distribution characteristics.The results indicated that compared with the traditional forced ventilation,the application of arc device can shorten the safe entry time after blasting operations by 9.9%–32.1%within the air supply volume of 804–1876 m3/min,effectively improving the construction efficiency and reducing the construction costs.In other words,the arc device can achieve the same dust control requirements with a smaller air supply volume,which improves the engineering applicability of forced ventilation in long-distance tunnel excavation while reducing ventilation energy consumption.Furthermore,the theoretical optimal combination scheme(L=35 m,Q=1876 m3/min,M=arc device)composed of the optimal levels of three factors achieved a 13%improvement in dust control compared to the experimental optimal combination scheme determined by the minimum safe entry time.This study can provide new strategies for improving the dust control performance of forced ventilation used in metro system construction.展开更多
基金National Key R&D Program of China(2022YFC2503200,2022YFC2503201)National Natural Science Foundation of China(52074012,52204191)+5 种基金Anhui Provincial Natural Science Foundation(2308085J19)University Distinguished Youth Foundation of Anhui Province(2022AH020057)Anhui Province University Discipline(Major)Top Talent Academic Support Project(gxbjZD2022017)Funding for academic research activities of reserve candidates for academic and technological leaders in Anhui Province(2022H301)Independent Research fund of Key Laboratory of Industrial Dust Prevention and Control&Occupational Health and Safety,Ministry of Education(Anhui University of Science and Technology)(EK20211004)Graduate Innovation Fund of Anhui University of Science and Technology(2023CX1003).
文摘In order to study the problems of unreasonable airflow distribution and serious dust pollution in a heading surface,an experimental platform for forced ventilation and dust removal was built based on the similar principles.Through the similar experiment and numerical simulation,the distribution of airflow field in the roadway and the spatial and temporal evolution of dust pollution under the conditions of forced ventilation were determined.The airflow field in the roadway can be divided into three zones:jet zone,vortex zone and reflux zone.The dust concentration gradually decreases from the head to the rear of the roadway.Under the forced ventilation conditions,there is a unilateral accumulation of dust,with higher dust concentrations away from the ducts.The position of the equipment has an interception effect on the dust.The maximum error between the test value and the simulation result is 12.9%,which verifies the accuracy of the experimental results.The research results can provide theoretical guidance for the application of dust removal technology in coal mine.
基金Projects(50978087,50908081)supported by the National Natural Science Foundation of China
文摘Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index （GI）, were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.
基金supported by the Program for Postgraduates Research Innovation in University of Jiangsu Province of China (No.CXLX13_955)the National Natural Science Foundation of China (No.51104153)
文摘In order to reveal the influence of forced ventilation on the dispersion of droplets ejected from roadheader-mounted external sprayer,the paper studies the air-flowing field and the droplet distribution under the condition of gentle breeze and normal forced ventilation in heading face using the particle tracking technology of computational fluid dynamics(CFD).The results show that air-flowing tendency in the same section presents great comparability in the period of gentle breeze and forced ventilation,and the difference mainly embodies in the different wind velocity.The influence of ventilation on the dispersion of droplets is faint under the gentle breeze condition.The droplet can be evenly distributed around the cutting head.However,under the normal forced ventilation,a large number of droplets will drift to the return air side.At the same time,droplet clusters are predominantly presented in the lower part of windward side and the middle of the leeward side around the cutting head.In contrast,the droplet concentration in other parts around cutting head decreases a lot and the droplets are unable to form close-grained mist curtain.So the dust escape channel is formed.In addition,the simulation results also reveal that the disturbance of air flow on the droplet distribution can be effectively relieved when using ventilation duct with Coanda effect(VDCE).Field experiment results show that the dust suppression efficiency of total dust and respirable dust increases respectively by 10.5%and 9.3%when using VDCE,which proves that it can weaken the influence of airflow on droplet dispersion.
基金supported by the National Key Research and Development Program(2016YFC0802205),Chinathe National Natural Science Foundation of China(No:64051578460),Chinathe National Key Research and Development Program of China(2016YFC0802200),China.
文摘Forced ventilation is typically used in the construction of tunnels since it is an economical method to provide high amounts of fresh air.Air velocity and pollutant concentration near the work face are determined by the ventilation arrangement.In the study,field measurement of air velocity was performed,and computational fluid dynamics(CFD)models were constructed to investigate airflow near the work face and predict the gas distribution in a gas tunnel construction.The effects of the distance between the air duct exit and the work face(L_(1))were evaluated by analyzing the flow field and pollutant concentration.The evaluation shows that the ventilation efficiency improves if L_(1) does not exceed 15 m in a road tunnel with full-face excavation.With respect to a road tunnel with benching excavation,the effects of bench length(L_(2))are analyzed,and the results of the analysis indicate that ventilation efficiency is optimal when L_(2)=5 m and L_(2)=10 m and the air-duct diameter corresponds to 1.6 m.The CFD results fit the field measurement significantly well,and the current ventilation system in the construction exhibits a relatively high efficiency.The findings of the study aid practitioners in optimizing ventilation efficiency.
文摘Pigs are subjected to intensive environment control and management for higher productivity due to their sensitivity to climatic variation, which affects their growth. The aim of the current work is to numerically model the air speed and temperature in a forced ventilation piggery to achieve optimum environmental control. This work can also help to identify problems in the design of piggeries and offer suggestions for improvements. A steady two-dimensional numerical model including the effect of buoyancy, turbulence and heat generated by the pigs was solved using the computational fluid dynamics software Fluent, using the integral volume method. Air speed and temperature inside the piggery and at the pigs level were predicted for three different locations of ventilation opening, inlet velocities in the range (0.3 - 7 m/s), insulation or no insulation in the external walls, and for 5 ℃ and 32℃ ambient temperatures.
文摘Pigs are subjected to intensive environment control and management in order to achieve higher productivity.This is due to their sensitivity to climatic variation,which strongly affects their growth.This paper reports the design optimization of a forced ventilation piggery using computational fl uid dynamics.This numerical investigation determined the effect of varying the number of ventilation openings and their location on the air fl ow pattern,speed,temperature,power needed,ability to remove heat and residence time.The effect of varying the ventilation rate in a range(0.05–0.8 m3/s),and ambient temperatures of 5°C and 32°C was also investigated.The modeled piggery has dimensions 40 m×15 m×2.6 m,with central walkway and gable roof with the apex at 3.9 m and is a common design in Australia.A steady-state two-dimensional numerical model based on the integral volume method,including the effects of buoyancy and heat generated by the pigs,was solved using the computational fl uid dynamics software“Fluent.”Four designs were investigated and an optimum design,which facilitates better ventilation of the majority of the room,has been identifi ed.In summer,an inlet velocity has been recommended which achieves optimum environment inside the piggery meeting the pigs’thermal comfort criteria with minimum power usage.During winter it became obvious that heating has to be used in all designs to be able to meet the pigs’thermal comfort criteria.
基金supported by the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents and Science Research Innovative Group of Resources and Environment Engineering College of Shandong University of Science and Technology (No. 2012ZHTD06)the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents (No. 2013RCJJ049)+1 种基金the China Postdoctoral Science Foundation (No. 2013M541942)the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20133718120013)
文摘Extraction of a coal seam which lies not far below a heating goafcan be a major safety challenge. A force auxiliary ventilation system was adopted as a control method in successful extraction and recovery of the panel 30110 of the #3-1 coal seam, which is about 30-40 rn below the heating goaf of the #2-2 seam at Longhua underground coal mine, Shanxi Province, China. Booster fans and ventilation control devices such as doors and regulators were used in the system. The results show that, provided that a force auxiliary ventilation system is properly designed to achieve a pressure balance between a panel and its overlying goat＇, the system can be used to extract a coal seam overlain by a heating goal. This paper describes the design, installation and performance of the ventilation system during the extraction and recovery phases of the oanel 30110.
基金supported by a DST project named“Development and performance analysis of Semi-Transparent Solar Photovoltaic double pane Window/Facade system”funded by the Department of Science and Technology,Government of India (TMD/CERI/BEE/2016/070(G)).
文摘Performance of Photovoltaic-double skin façade(Photovoltaic-DSF)system in summer has been critical.Owing to high solar ingress,cooling requirement of a building significantly increases.Photovoltaic-DSF system provides a shield and controls the heat gain through fenestration in the interior spaces.In the present article,mathematical correlations are developed for energy characterization of forced-ventilated Photovoltaic-DSF system in India’s hot summer zone i.e.Jaipur.The Photovoltaic-DSF system has been installed and monitored for Jaipur’s summer months(May to July).L25 Orthogonal array of design parameters(air cavity thickness,air velocity,and PV panel’s transparency)and their respective levels have been developed using Taguchi design to perform experiments.Based on experimental results,multiple linear regression has been used to forecast solar heat gain coefficient,PVs electrical power and daylighting illuminance indoors as function of design factors.The statistical significance of mathematical relationships is sorted by variance analysis,which is found to be in good accord with field measurements(R2>0.90).The proposed correlations are pragmatic in designing Photovoltaic-DSF systems for hot summer conditions.The Photovoltaic-DSF system with 30%transmittance and air velocity of 5 metres per second in 200 mm air cavity thickness achieved maximum energy performance in hot summers.
基金LIFE-funded project(LIFE20 ENV/ES/000187)It was also supported by the Spanish Ministry of Science and Innovation(Project CEX2018000794-S)and by AGAUR(project 2021 SGR 00341).
文摘In industrial scenarios,nanoparticles are incidentally generated in high concentrations during diverse material transformation processes,presenting potential health hazards for exposed workers.Consequently,as an indoor air quality management measure,their concentration is commonly reduced through localized forced ventilation.However,the control of these systems usually relies on traditional rule-based algorithms,which cannot deploy efficient control strategies such as model predictive control.To solve this issue,we propose a novel grey-box reduced order model method,never used before for industrial indoor nanoparticles.This approach can be deployed in model predictive control algorithms in buildings and does not present the data-reliance and transferability issues of black-box modeling.To test this model,a data collection campaign was conducted under real-world operating conditions in an industrial-scale thermal spraying booth,aiming to test the method’s viability for model calibration and validation of indoor total nanoparticle concentration through the maximum likelihood method,statistical validation tests,and physical viability assessment.Results for three different lumped sum models illustrate the effectiveness of grey-box modeling in industrial scenarios with confined processes and forced ventilation systems,handling observations’noise and background concentration fluctuations,and allowing a performance comparison between models.Further research could be conducted to study the viability of indoor total nanoparticle concentration reduced order models with higher spatial resolution,non-confined sources,and natural airflows.
基金financially supported by National Natural Science Foundation of China(52408106).
文摘Metro systems play a crucial role in enhancing the urban economy,but the serious dust pollution during its construction poses a significant threat to the health of workers.Widely used for dust control in metro systems,the current forced ventilation technology is characterized by low dust control efficiency.In this study,an innovative arc device with efficient dust control and convenient application was proposed based on the forced ventilation.Subsequently,the orthogonal experimental method was adopted to explore the effects of air supply outlet position(L),air supply volume(Q),and air supply mode(M)on the airflow-dust distribution characteristics.The results indicated that compared with the traditional forced ventilation,the application of arc device can shorten the safe entry time after blasting operations by 9.9%–32.1%within the air supply volume of 804–1876 m3/min,effectively improving the construction efficiency and reducing the construction costs.In other words,the arc device can achieve the same dust control requirements with a smaller air supply volume,which improves the engineering applicability of forced ventilation in long-distance tunnel excavation while reducing ventilation energy consumption.Furthermore,the theoretical optimal combination scheme(L=35 m,Q=1876 m3/min,M=arc device)composed of the optimal levels of three factors achieved a 13%improvement in dust control compared to the experimental optimal combination scheme determined by the minimum safe entry time.This study can provide new strategies for improving the dust control performance of forced ventilation used in metro system construction.
