Particulate pollution is main kind of atmospheric pollution.The fine particles are seriously harmful to human health and environment.Acoustic agglomeration is considered as a promising pretreatment technology for fine...Particulate pollution is main kind of atmospheric pollution.The fine particles are seriously harmful to human health and environment.Acoustic agglomeration is considered as a promising pretreatment technology for fine particle agglomeration.The mechanisms of acoustic agglomeration are very complex and the agglomeration efficiency is affected by many factors.The most important and controversial factor is frequency.Comparative studies between high-frequency and low-frequency sound source to agglomerate coal- fired fly ash were carried out to investigate the influence of frequency on agglomeration efficiency.Acoustic agglomeration theoretical analysis,experimental particle size distributions （PSDs） and orthogonal design were examined.The results showed that the 20 kHz high-frequency sound source was not suitable to agglomerate coal-fired fly ash.Only within the size ranging from 0.2 to 0.25 μm the particles agglomerated to adhere together,and the agglomerated particles were smaller than 2.5 μm.The application of low-frequency （1000–1800 Hz） sound source was proved as an advisable pretreatment with the highest agglomeration efficiency of 75.3%,and all the number concentrations within the measuring range decreased.Orthogonal design L16 （4） 3 was introduced to determine the optimum frequency and optimize acoustic agglomeration condition.According to the results of orthogonal analysis,frequency was the dominant factor of coal-fired fly ash acoustic agglomeration and the optimum frequency was 1400 Hz.展开更多
The increasing complexity of urban buildings has significantly heightened fire risks,posing serious threats to public safety.In the event of a fire,smoke particles scatter and absorb light,drastically reducing visibil...The increasing complexity of urban buildings has significantly heightened fire risks,posing serious threats to public safety.In the event of a fire,smoke particles scatter and absorb light,drastically reducing visibility and greatly endangering trapped individuals.Existing smoke control methods face notable limitations.Natural ventilation is susceptible to environmental conditions.Solid obstructions such as firewalls can impede evacuation.Fine water mist may remain suspended in air and reduce visibility.Moreover,these approaches do not directly control smoke particles,so there is a need for innovative solutions.Acoustic agglomeration,which leverages high-intensity acoustic fields to induce relative motion among smoke particles and facilitate rapid agglomeration,is a promising technology for improving visibility in smoke-filled environments.It operates independently of ambient conditions,does not require solid barriers,and introduces no additional particles,which underscores its advantages for evacuation and rescue.This review synthesizes the development,mechanisms,operating parameters,sound sources,and hybrid strategies of acoustic agglomeration for fire smoke control,identifies remaining gaps,and assesses feasibility.The insights are intended to support researchers and decision-makers in advancing more effective smoke control strategies.展开更多
To test the particles solidity and to verify the separating efficiency at normal atmospheric temperature, the experimental research was made on the enhanced cyclone separation of acoustic agglomerated fly ash particl...To test the particles solidity and to verify the separating efficiency at normal atmospheric temperature, the experimental research was made on the enhanced cyclone separation of acoustic agglomerated fly ash particles. The separating efficiency has increased by 3%-4% in a sound field with 150 dB pressure level compared with that obtained without acoustic wave processing. The enhanced cyclone separation test study for acoustic agglomerated particles has provided a technical basis for pressurized fluid bed combustion(PFBC) application.展开更多
To explore the effectiveness of acoustic agglomeration technology in eliminating urban fire smoke, an experimental setup for eliminating continuous smoke is built. This study uses airborne ultrasonic transducers as th...To explore the effectiveness of acoustic agglomeration technology in eliminating urban fire smoke, an experimental setup for eliminating continuous smoke is built. This study uses airborne ultrasonic transducers as the sound source, with resonant frequencies are 13, 16, 18, and 20 kHz, respectively. Typical urban fire smoke is produced by the combustion of materials such as polystyrene (PS), polyvinyl chloride (PVC), carton, cotton, pine sawdust, and birch sawdust. The effects of ultrasonic frequency, sound pressure level, residence time and initial concentration on the elimination of both single material smoke and mixed material smoke types are investigated. Results indicate that the 16 kHz sound waves are most effective for PS, PVC, and carton smoke, whereas the optimum frequency for birch smoke is between 16 and 18 kHz. The optimal frequency of mixed smoke is significantly influenced by particle size and the ratio of large to small particles. When the sound pressure level is 142–154 dB, and the residence time is 4 s, the visibility of all types of smoke increased from 1 m to above the safe escape threshold (2.5 m). Furthermore, higher initial concentrations of smoke result in more effective elimination.展开更多
Acoustic agglomeration technology use high-intensity acoustic field to make aerosol particles collide and condense rapidly. Existing studies have shown that 70%–90% of fine particles can be eliminated within minutes ...Acoustic agglomeration technology use high-intensity acoustic field to make aerosol particles collide and condense rapidly. Existing studies have shown that 70%–90% of fine particles can be eliminated within minutes using compression drives and air-jet generators. Currently, there are limitations to the sound sources used. In this paper, an airborne ultrasonic transducer with a resonant frequency of 15 kHz is designed, followed by the corresponding numerical simulation and experiments for the evaluation of the vibration modal and sound pressure field. The sound pressure levels (SPL) of the open space and the agglomeration chamber can reach 150 dB and 156 dB, respectively. The agglomeration effect of water droplets, liquid phase smoke, solid phase smoke and mixed smoke is experimentally investigated, and the light transmittance rapidly increases from 8% to 60% within 4 s, 8 s, 5 s and 6 s, respectively. Agglomeration is also effective in the high-frequency range, and we infer that the acoustic wake effect is the predominant mechanism. The elimination effect is promoted with the increasing of SPL until the corresponding secondary acoustic effect is enhanced. Moreover, the agglomeration rate of higher concentration aerosol is significantly better than that of diluted aerosols in ultrasonic agglomeration process.展开更多
基金supported by the National Basic Re-search Program (973) of China(No.2010CB227001)the National Natural Science Foundation of China(No.50576083)+1 种基金the Program New Century Excellent Talents University(No.NCET-04-0533)the Zhejiang Provin-cial Natural Science Foundation of China(No.Y1100299)
文摘Particulate pollution is main kind of atmospheric pollution.The fine particles are seriously harmful to human health and environment.Acoustic agglomeration is considered as a promising pretreatment technology for fine particle agglomeration.The mechanisms of acoustic agglomeration are very complex and the agglomeration efficiency is affected by many factors.The most important and controversial factor is frequency.Comparative studies between high-frequency and low-frequency sound source to agglomerate coal- fired fly ash were carried out to investigate the influence of frequency on agglomeration efficiency.Acoustic agglomeration theoretical analysis,experimental particle size distributions （PSDs） and orthogonal design were examined.The results showed that the 20 kHz high-frequency sound source was not suitable to agglomerate coal-fired fly ash.Only within the size ranging from 0.2 to 0.25 μm the particles agglomerated to adhere together,and the agglomerated particles were smaller than 2.5 μm.The application of low-frequency （1000–1800 Hz） sound source was proved as an advisable pretreatment with the highest agglomeration efficiency of 75.3%,and all the number concentrations within the measuring range decreased.Orthogonal design L16 （4） 3 was introduced to determine the optimum frequency and optimize acoustic agglomeration condition.According to the results of orthogonal analysis,frequency was the dominant factor of coal-fired fly ash acoustic agglomeration and the optimum frequency was 1400 Hz.
基金supported by the National Natural Science Foundation of China(grant No.52276162).
文摘The increasing complexity of urban buildings has significantly heightened fire risks,posing serious threats to public safety.In the event of a fire,smoke particles scatter and absorb light,drastically reducing visibility and greatly endangering trapped individuals.Existing smoke control methods face notable limitations.Natural ventilation is susceptible to environmental conditions.Solid obstructions such as firewalls can impede evacuation.Fine water mist may remain suspended in air and reduce visibility.Moreover,these approaches do not directly control smoke particles,so there is a need for innovative solutions.Acoustic agglomeration,which leverages high-intensity acoustic fields to induce relative motion among smoke particles and facilitate rapid agglomeration,is a promising technology for improving visibility in smoke-filled environments.It operates independently of ambient conditions,does not require solid barriers,and introduces no additional particles,which underscores its advantages for evacuation and rescue.This review synthesizes the development,mechanisms,operating parameters,sound sources,and hybrid strategies of acoustic agglomeration for fire smoke control,identifies remaining gaps,and assesses feasibility.The insights are intended to support researchers and decision-makers in advancing more effective smoke control strategies.
文摘To test the particles solidity and to verify the separating efficiency at normal atmospheric temperature, the experimental research was made on the enhanced cyclone separation of acoustic agglomerated fly ash particles. The separating efficiency has increased by 3%-4% in a sound field with 150 dB pressure level compared with that obtained without acoustic wave processing. The enhanced cyclone separation test study for acoustic agglomerated particles has provided a technical basis for pressurized fluid bed combustion(PFBC) application.
基金supported by the National Natural Science Foundation of China(grant Nos.52276162 and 52306207).
文摘To explore the effectiveness of acoustic agglomeration technology in eliminating urban fire smoke, an experimental setup for eliminating continuous smoke is built. This study uses airborne ultrasonic transducers as the sound source, with resonant frequencies are 13, 16, 18, and 20 kHz, respectively. Typical urban fire smoke is produced by the combustion of materials such as polystyrene (PS), polyvinyl chloride (PVC), carton, cotton, pine sawdust, and birch sawdust. The effects of ultrasonic frequency, sound pressure level, residence time and initial concentration on the elimination of both single material smoke and mixed material smoke types are investigated. Results indicate that the 16 kHz sound waves are most effective for PS, PVC, and carton smoke, whereas the optimum frequency for birch smoke is between 16 and 18 kHz. The optimal frequency of mixed smoke is significantly influenced by particle size and the ratio of large to small particles. When the sound pressure level is 142–154 dB, and the residence time is 4 s, the visibility of all types of smoke increased from 1 m to above the safe escape threshold (2.5 m). Furthermore, higher initial concentrations of smoke result in more effective elimination.
基金supported by the National Natural Science Foundation of China(Grant No.52276162 and 51876197)the Fundamental Research Funds for the Provincial Universities of Zhejiang.
文摘Acoustic agglomeration technology use high-intensity acoustic field to make aerosol particles collide and condense rapidly. Existing studies have shown that 70%–90% of fine particles can be eliminated within minutes using compression drives and air-jet generators. Currently, there are limitations to the sound sources used. In this paper, an airborne ultrasonic transducer with a resonant frequency of 15 kHz is designed, followed by the corresponding numerical simulation and experiments for the evaluation of the vibration modal and sound pressure field. The sound pressure levels (SPL) of the open space and the agglomeration chamber can reach 150 dB and 156 dB, respectively. The agglomeration effect of water droplets, liquid phase smoke, solid phase smoke and mixed smoke is experimentally investigated, and the light transmittance rapidly increases from 8% to 60% within 4 s, 8 s, 5 s and 6 s, respectively. Agglomeration is also effective in the high-frequency range, and we infer that the acoustic wake effect is the predominant mechanism. The elimination effect is promoted with the increasing of SPL until the corresponding secondary acoustic effect is enhanced. Moreover, the agglomeration rate of higher concentration aerosol is significantly better than that of diluted aerosols in ultrasonic agglomeration process.
