Polyaluminum chloride (PAC) was used as coagulant and suspended particles in kaolin water. Online instruments including turbidimeter and particle counter were used to monitor the flocculation process. An evaluation ...Polyaluminum chloride (PAC) was used as coagulant and suspended particles in kaolin water. Online instruments including turbidimeter and particle counter were used to monitor the flocculation process. An evaluation model for demonstrating the impact on the flocculation effect was established based on the multiple linear regression analysis method. The parameter of the index weight of channels quantitatively described how the variation of floc particle population in different size ranges cause the decrement of turbidity. The study showed that the floc particles in different size ranges contributed differently to the decrease of turbidity and that the index weight of channel could excellently indicate the impact degree of floc particles dynamic distribution on flocculation effect. Therefore, the parameter may significantly benefit the development of coagulation and sedimentation techniques as well as the optimal coagulant selection.展开更多
The JC-CA300 handheld Aerosol particle counter is designed and developed based on light scattering principle. The JC-CA300 counter is composed of optical sensor, DSP component and microprocessor unit. The hardware arc...The JC-CA300 handheld Aerosol particle counter is designed and developed based on light scattering principle. The JC-CA300 counter is composed of optical sensor, DSP component and microprocessor unit. The hardware architecture is designed in compact style by SMT IC chips. The whole counter weight is less than 2 pounds. With 32K RAM space, the JC-CA300 can store 500 sampling records and support standard printer and communicate with a computer through RS232 interface. Based on experimental results, the main performance of JC-CA300 is better than that of the ARTI'S HHPC-6 instrument.展开更多
This review covers the progress of light scattering applications in the field of particle characterization in the past decade. The review addresses static light scattering (the measurement of scattering intensities d...This review covers the progress of light scattering applications in the field of particle characterization in the past decade. The review addresses static light scattering (the measurement of scattering intensities due to light-particle interaction at various spatial locations), dynamic light scattering (the measurement of scattering due to light-particle interaction as a function of time), and scattering tracking analysis (the tracking of particle movement through scattering measurement).展开更多
A model for measuring aerosol mass concentration by an optical particle counter is presented using the conception of the average mass. In this model, to understand the meaning of the pulse height distribution of parti...A model for measuring aerosol mass concentration by an optical particle counter is presented using the conception of the average mass. In this model, to understand the meaning of the pulse height distribution of particles which is used to inverse mass concentration, the relationship among intensity distribution in the optical sensing volume, particle shape, and the pulse height distribution is discussed. To solve the instability of the equivalent factor, a novel two-step calibration method is proposed. The experimental results demonstrate that mass concentrations calculated by the model are in good agreement with those measured by a norm-referenced instrument. For samples of soot and air, the slopes of fitting lines of data points are 0.9582 and 0.9220, and the correlation coefficients are 0.9991 and 0.9965, respectively.展开更多
This study selected polyaluminum chloride(PAC) coagulant to remove suspended particles in Kaolin suspension solution and used a turbidimeter and particle counter to monitor the flocculation process online and collec...This study selected polyaluminum chloride(PAC) coagulant to remove suspended particles in Kaolin suspension solution and used a turbidimeter and particle counter to monitor the flocculation process online and collected the experiment data. The experiments were conducted to study the dynamic distribution characteristics of suspended particles under different hydrodynamic conditions. The results show the self-similarity and scale invariance of particle size distribution. The study further proposed the concept of fractal dimension of particle size distribution and found out that fractal dimension changed in a similar way as residual turbidity did and could excellently indicate the variation of coagulation effect. Therefore, fractal dimension could be adopted to optimize the addition of coagulants and the quality of outflow could be further improved to reduce production costs.展开更多
This study presents the development of a medium flow, multiple slit based PM2.5 (particle aerodynamic diameter 〈2.5 μm) inertial impactor. Its performance was compared with that of a light scattering based optical...This study presents the development of a medium flow, multiple slit based PM2.5 (particle aerodynamic diameter 〈2.5 μm) inertial impactor. Its performance was compared with that of a light scattering based optical particle sizer in a field study and in controlled lab based experiments using polydisperse dolomite powder as test aerosol. The impactor's optimum nozzle configuration had a cutoff size of 2.51 μm (aero- dynamic diameter) at an operating flow rate of 215 L/rain with a pressure drop of 0.35 kPa across the impactor stage. Because the apparent particle density of an ambient aerosol depends on the physical properties and the chemical composition of the particles, the PM2.5 mass concentration was measured with an optical particle sizer and an inertial impactor over a weekday and a weekend day in a field study during which the effective particle shape factor and density were in tandem modified in order to com- pare the results from the two sampling techniques. The correlation of the two instrument results tended towards 1:1 with increasing values of shape factor (irregular shaped) and effective particle density. This observation was supported through chemical investigations of the collected mass, which showed a higher percentage contribution from elements which are mostly of crustal nature (namely, Ca, Fe, and Mg).展开更多
Particulate mass concentration (PM10, PM2.5), aerosol number concentration (NOPC), aerosol size distribu-tion and atmospheric visibility were simultaneously measured in Beijing in the summer and winter of 2001. From t...Particulate mass concentration (PM10, PM2.5), aerosol number concentration (NOPC), aerosol size distribu-tion and atmospheric visibility were simultaneously measured in Beijing in the summer and winter of 2001. From the profuse data collected, the following conclusions can be drown: (1) there are two peaks for the average diurnal variations of PM10 and NOPC in the summer, an obvious valley can be seen between 12:30 and 15:00 for their average diurnal variation in the winter; (2) there is one single peak for the average diurnal variation of atmospheric visibility in the summer, while there are two peaks in the winter; (3) PM10 and NOPC are usually smaller in the summer than those in the winter; (4) the average visibility is much lower during 00:00~09:00 in the summer than that in the winter, because of the very high relative humidity and higher concentration of the large particles (r>1.25 mm) in the summer during the period; (5) aerosol size distributions usually depend closely on season and relative humidity at the same place.展开更多
基金supported by the National Natural Science Foundation of China (No. 50678047)the National High Technology Research and Development Program of China (No. 2006AA06Z305)the National Science and Technology Project of Eleventh Five Years (No.2006BAJ08B05-2)
文摘Polyaluminum chloride (PAC) was used as coagulant and suspended particles in kaolin water. Online instruments including turbidimeter and particle counter were used to monitor the flocculation process. An evaluation model for demonstrating the impact on the flocculation effect was established based on the multiple linear regression analysis method. The parameter of the index weight of channels quantitatively described how the variation of floc particle population in different size ranges cause the decrement of turbidity. The study showed that the floc particles in different size ranges contributed differently to the decrease of turbidity and that the index weight of channel could excellently indicate the impact degree of floc particles dynamic distribution on flocculation effect. Therefore, the parameter may significantly benefit the development of coagulation and sedimentation techniques as well as the optimal coagulant selection.
文摘The JC-CA300 handheld Aerosol particle counter is designed and developed based on light scattering principle. The JC-CA300 counter is composed of optical sensor, DSP component and microprocessor unit. The hardware architecture is designed in compact style by SMT IC chips. The whole counter weight is less than 2 pounds. With 32K RAM space, the JC-CA300 can store 500 sampling records and support standard printer and communicate with a computer through RS232 interface. Based on experimental results, the main performance of JC-CA300 is better than that of the ARTI'S HHPC-6 instrument.
文摘This review covers the progress of light scattering applications in the field of particle characterization in the past decade. The review addresses static light scattering (the measurement of scattering intensities due to light-particle interaction at various spatial locations), dynamic light scattering (the measurement of scattering due to light-particle interaction as a function of time), and scattering tracking analysis (the tracking of particle movement through scattering measurement).
基金the Doctor Creation Foundation of Nanjing University of Science and Technology
文摘A model for measuring aerosol mass concentration by an optical particle counter is presented using the conception of the average mass. In this model, to understand the meaning of the pulse height distribution of particles which is used to inverse mass concentration, the relationship among intensity distribution in the optical sensing volume, particle shape, and the pulse height distribution is discussed. To solve the instability of the equivalent factor, a novel two-step calibration method is proposed. The experimental results demonstrate that mass concentrations calculated by the model are in good agreement with those measured by a norm-referenced instrument. For samples of soot and air, the slopes of fitting lines of data points are 0.9582 and 0.9220, and the correlation coefficients are 0.9991 and 0.9965, respectively.
基金The National High Technology Research and Development Program of China(863 Program) (2006AA06Z305)the National Science and Technology Project of Eleventh Five Years(2006BAJ08B05-2)Supported by the National Natural Science Foundation of China(50678047)
文摘This study selected polyaluminum chloride(PAC) coagulant to remove suspended particles in Kaolin suspension solution and used a turbidimeter and particle counter to monitor the flocculation process online and collected the experiment data. The experiments were conducted to study the dynamic distribution characteristics of suspended particles under different hydrodynamic conditions. The results show the self-similarity and scale invariance of particle size distribution. The study further proposed the concept of fractal dimension of particle size distribution and found out that fractal dimension changed in a similar way as residual turbidity did and could excellently indicate the variation of coagulation effect. Therefore, fractal dimension could be adopted to optimize the addition of coagulants and the quality of outflow could be further improved to reduce production costs.
文摘This study presents the development of a medium flow, multiple slit based PM2.5 (particle aerodynamic diameter 〈2.5 μm) inertial impactor. Its performance was compared with that of a light scattering based optical particle sizer in a field study and in controlled lab based experiments using polydisperse dolomite powder as test aerosol. The impactor's optimum nozzle configuration had a cutoff size of 2.51 μm (aero- dynamic diameter) at an operating flow rate of 215 L/rain with a pressure drop of 0.35 kPa across the impactor stage. Because the apparent particle density of an ambient aerosol depends on the physical properties and the chemical composition of the particles, the PM2.5 mass concentration was measured with an optical particle sizer and an inertial impactor over a weekday and a weekend day in a field study during which the effective particle shape factor and density were in tandem modified in order to com- pare the results from the two sampling techniques. The correlation of the two instrument results tended towards 1:1 with increasing values of shape factor (irregular shaped) and effective particle density. This observation was supported through chemical investigations of the collected mass, which showed a higher percentage contribution from elements which are mostly of crustal nature (namely, Ca, Fe, and Mg).
文摘Particulate mass concentration (PM10, PM2.5), aerosol number concentration (NOPC), aerosol size distribu-tion and atmospheric visibility were simultaneously measured in Beijing in the summer and winter of 2001. From the profuse data collected, the following conclusions can be drown: (1) there are two peaks for the average diurnal variations of PM10 and NOPC in the summer, an obvious valley can be seen between 12:30 and 15:00 for their average diurnal variation in the winter; (2) there is one single peak for the average diurnal variation of atmospheric visibility in the summer, while there are two peaks in the winter; (3) PM10 and NOPC are usually smaller in the summer than those in the winter; (4) the average visibility is much lower during 00:00~09:00 in the summer than that in the winter, because of the very high relative humidity and higher concentration of the large particles (r>1.25 mm) in the summer during the period; (5) aerosol size distributions usually depend closely on season and relative humidity at the same place.