Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for applic... more Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for application as hot aerosol filtering membrane. The procedure for establishment of membrane features required to maintain a desired flow condition was theoretically described and experimental work was designed to prepare ceramic membranes to meet the predicted criteria. Two best membranes, thus prepared, were selected for permeability tests up to 700 degrees C and their total and fractional collection efficiencies were experimentally evaluated. Reasonably good performance was achieved at room temperature, while at 700 degrees C, increased permeability was obtained with significant reduction in collection efficiency, which was explained by a combination of thermal expansion of the structure and changes in the gas properties.
The aim of the present work was to investigate the influence of operational variables in the nano... more The aim of the present work was to investigate the influence of operational variables in the nanoparticle loss to the duct walls, for nanoparticle laden aerosols. Several tests were carried out changing the aerosol flow rate, the tube diameter and the tube length. The effect of these variable in the total number of particles and in the median particle diameter after the tube was measured using the SMPS (Scanning Mobility Particle Sizer) particle analyzer. The results showed considerable loss of wall for particles smaller than 100 nm. Also, disagreement between theory and experiment occurs in this size range, indicating that the understanding of the mechanism of particle deposition needs further investigation.
Estruturas fibrosas são especialmente indicadas para filtração a temperaturas elevadas, pela alta... more Estruturas fibrosas são especialmente indicadas para filtração a temperaturas elevadas, pela alta permeabilidade aliada à alta capacidade de retenção. Mantas refratárias silico-aluminosas comerciais foram prensadas uniaxialmente, utilizando-se 10% em massa de acetato de polivinila como ligante. Após a prensagem, as amostras foram submetidas a um tratamento térmico a 750°C durante 1 hora, para oxidação do polímero. Subseqüentemente, as amostras foram sinterizadas a temperaturas de 900°C e 1200°C durante 1 hora, resultando em uma estrutura fibrilar porosa com densidades relativas entre 0,28 e 0,43, que correspondem a porosidades na faixa de 53% a 71%, respectivamente. A microestrutura das amostras foi caracterizada por microscopia eletrônica de varredura. Em razão da temperatura, ensaios de permeabilidade foram efetuados e os resultados comparados aos filtros existentes. Os valores obtidos para a permeabilidade darciana, k1, estão na ordem de grandeza esperada para filtros de gases, a...
International Journal of Environment and Pollution, 2010
ABSTRACT The temporal trends of PM<sub align="right">2.5 and PM&a... more ABSTRACT The temporal trends of PM<sub align="right">2.5 and PM<sub align="right">10−2.5 fractions of the atmospheric Particulate Matter (PM) concentrations in the city centre of Sao Carlos were studied. The mass concentrations were measured using a dichotomous sampler. The samples were obtained weekly using a 24-hour sampling time, and the period of study covers the years 2001 to 2006. The SARIMA model from the R statistical package was used for modelling. The SARIMA obtained for each series of PM were compared to results obtained with the Holt–Winters method. Both models provided satisfactory results and were sensitive to seasonal and local events. They can, therefore, be successfully used as an analytical tool for similar atmospheric studies elsewhere. The SARIMA results showed better prediction performance, with smaller values of RMSE and RMSE percentage (values of 4.67 and 0.92% for the PM<sub align="right">2.5 and 4.55 and 2.73% for PM<sub align="right">10−2.5, respectively) than the Holt–Winters models.
The aim of the present work was to investigate the particle loss to walls during the flow of the ... more The aim of the present work was to investigate the particle loss to walls during the flow of the nanoparticles through ducts. Operational conditions to investigate this loss during the flow through circular tubes were determined with nine parameters under consideration: aerosol flow rate, the tube diameter and the tube length. The influence of these three variables was studied using a 2 3 full factorial design and axial points with a total of 18 experiments. Response surface methodology was adopted and an empirical linear polynomial model constructed. The results showed that total number of particles depend on the tube length and diameter, whilst the particle median diameter was strongly dependent on the tube diameter. INTRODUCTION The sizing of nanoparticles present in aerosols, inevitably, involves sampling and transport of the solid suspension, usually through tubing. In the last years, there is an increasing advance in the technological applications of nanoparticles. This intere...
The Venturi scrubber is used for removing particulate matter from gaseous effluents and finds a l... more The Venturi scrubber is used for removing particulate matter from gaseous effluents and finds a large application in industry. The size of the droplet is of fundamental importance to the performance of the equipment. This work aims at studying the effect of some design parameters, namely liquid flow rate and liquid injection system in the droplet size and to correlate this with collection efficiency. A laser diffraction technique was used in order to measure droplet size in situ in a rectangular Venturi scrubber, with liquid injected through 1mm diameter orifices on the throat walls. Liquid flow rates of 600 and 900 ml/min and number of orifices varying from 1 to 5 were used in the experiments. The throat gas velocity was kept at 69.3 m/s. It was found that all these variables significantly affected droplet size. The results of droplet size were compared with the particle capture (collection) efficiency measured in the same experimental conditions. It was observed that the collectio...
A Pease-Anthony Venturi scrubber is a relatively simple and very efficient device used for gas cl... more A Pease-Anthony Venturi scrubber is a relatively simple and very efficient device used for gas cleaning. This paper presents photographic images of the atomization of a liquid jet in the throat of a Pease-Anthony Venturi scrubber, obtained through the development and use of an electronic flash of short duration. This new evidence was used to improve the parameters of the model of Gonçalves et al. (2000) [1]. The experimental conditions used were: throat gas velocities between 59 and 74m/s, jet velocities between 3.18 and 19.10m/s and liquid injected into the throat through different orifices.
Venturi scrubbers are widely utilized in gas cleaning. The cleansing elements in these scrubbers ... more Venturi scrubbers are widely utilized in gas cleaning. The cleansing elements in these scrubbers are droplets formed from the atomization of a liquid into a dust-laden gas. In industrial scrubbers, this liquid is injected through several orifices so that the cloud of droplets can be evenly distributed throughout the duct. The interaction between droplets when injected through many orifices, where opposite clouds of atomized liquid can reach each other, is to be expected. This work presents experimental measurements of droplet size measured in situ and the evidence of cloud interaction within a Venturi scrubber operating with multi-orifice jet injection. The influence of gas velocity, liquid flow rate and droplet size variation in the axial position after the point of the injection of the liquid were also evaluated for the different injection configurations. The experimental results showed that an increase in the liquid flow rate generated greater interaction between jets. The number of orifices had a significant influence on droplet size. In general, the increase in the velocity of the liquid jet and in the gas velocity favored the atomization process by reducing the size of the droplets.
International Journal of Environment and Pollution, 2002
ABSTRACT A survey on the concentration of particulate matter in the urban atmosphere was carried ... more ABSTRACT A survey on the concentration of particulate matter in the urban atmosphere was carried out in the city of Sao Carlos, Brazil. Five sites were selected for data collection one in the city centre (high concentration of people and automotive vehicles), three in industrial areas, and one at the interface with the countryside. The particle size distribution and mass concentration, temperature, humidity and wind velocity were measured at each site. In the city centre, the concentration of the particles smaller than 10 µm (PM<sub align="right"> 10 ) was also measured. The particle size distribution was obtained with a laser scattering particle counter. The total and PM<sub align="right"> 10 concentrations were obtained with high volume samplers. The tests were performed for 75 consecutive weeks. The results show that the particle concentration is sensitive to seasonal conditions. During autumn and winter, which is the drier and windy period of the year, larger particles were dispersed, leading to higher concentrations, both total and PM<sub align="right"> 10 . The relative humidity varied with the schedule of sampling and with the season the autumn and winter weeks were much drier than the other periods. Higher rainfall levels coincided with lower particle concentrations. All these results are statistically significant.
The centrifuge technique was used to investigate the influence of particle size, applied compress... more The centrifuge technique was used to investigate the influence of particle size, applied compression, and substrate material (stainless steel, glass, Teflon, and poly (vinyl chloride)) on particle− surface adhesion force. For this purpose, phosphatic rock (ρp= 3090 kg/m3) ...
Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for applic... more Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for application as hot aerosol filtering membrane. The procedure for establishment of membrane features required to maintain a desired flow condition was theoretically described and experimental work was designed to prepare ceramic membranes to meet the predicted criteria. Two best membranes, thus prepared, were selected for permeability tests up to 700 degrees C and their total and fractional collection efficiencies were experimentally evaluated. Reasonably good performance was achieved at room temperature, while at 700 degrees C, increased permeability was obtained with significant reduction in collection efficiency, which was explained by a combination of thermal expansion of the structure and changes in the gas properties.
The aim of the present work was to investigate the influence of operational variables in the nano... more The aim of the present work was to investigate the influence of operational variables in the nanoparticle loss to the duct walls, for nanoparticle laden aerosols. Several tests were carried out changing the aerosol flow rate, the tube diameter and the tube length. The effect of these variable in the total number of particles and in the median particle diameter after the tube was measured using the SMPS (Scanning Mobility Particle Sizer) particle analyzer. The results showed considerable loss of wall for particles smaller than 100 nm. Also, disagreement between theory and experiment occurs in this size range, indicating that the understanding of the mechanism of particle deposition needs further investigation.
Estruturas fibrosas são especialmente indicadas para filtração a temperaturas elevadas, pela alta... more Estruturas fibrosas são especialmente indicadas para filtração a temperaturas elevadas, pela alta permeabilidade aliada à alta capacidade de retenção. Mantas refratárias silico-aluminosas comerciais foram prensadas uniaxialmente, utilizando-se 10% em massa de acetato de polivinila como ligante. Após a prensagem, as amostras foram submetidas a um tratamento térmico a 750°C durante 1 hora, para oxidação do polímero. Subseqüentemente, as amostras foram sinterizadas a temperaturas de 900°C e 1200°C durante 1 hora, resultando em uma estrutura fibrilar porosa com densidades relativas entre 0,28 e 0,43, que correspondem a porosidades na faixa de 53% a 71%, respectivamente. A microestrutura das amostras foi caracterizada por microscopia eletrônica de varredura. Em razão da temperatura, ensaios de permeabilidade foram efetuados e os resultados comparados aos filtros existentes. Os valores obtidos para a permeabilidade darciana, k1, estão na ordem de grandeza esperada para filtros de gases, a...
International Journal of Environment and Pollution, 2010
ABSTRACT The temporal trends of PM<sub align="right">2.5 and PM&a... more ABSTRACT The temporal trends of PM<sub align="right">2.5 and PM<sub align="right">10−2.5 fractions of the atmospheric Particulate Matter (PM) concentrations in the city centre of Sao Carlos were studied. The mass concentrations were measured using a dichotomous sampler. The samples were obtained weekly using a 24-hour sampling time, and the period of study covers the years 2001 to 2006. The SARIMA model from the R statistical package was used for modelling. The SARIMA obtained for each series of PM were compared to results obtained with the Holt–Winters method. Both models provided satisfactory results and were sensitive to seasonal and local events. They can, therefore, be successfully used as an analytical tool for similar atmospheric studies elsewhere. The SARIMA results showed better prediction performance, with smaller values of RMSE and RMSE percentage (values of 4.67 and 0.92% for the PM<sub align="right">2.5 and 4.55 and 2.73% for PM<sub align="right">10−2.5, respectively) than the Holt–Winters models.
The aim of the present work was to investigate the particle loss to walls during the flow of the ... more The aim of the present work was to investigate the particle loss to walls during the flow of the nanoparticles through ducts. Operational conditions to investigate this loss during the flow through circular tubes were determined with nine parameters under consideration: aerosol flow rate, the tube diameter and the tube length. The influence of these three variables was studied using a 2 3 full factorial design and axial points with a total of 18 experiments. Response surface methodology was adopted and an empirical linear polynomial model constructed. The results showed that total number of particles depend on the tube length and diameter, whilst the particle median diameter was strongly dependent on the tube diameter. INTRODUCTION The sizing of nanoparticles present in aerosols, inevitably, involves sampling and transport of the solid suspension, usually through tubing. In the last years, there is an increasing advance in the technological applications of nanoparticles. This intere...
The Venturi scrubber is used for removing particulate matter from gaseous effluents and finds a l... more The Venturi scrubber is used for removing particulate matter from gaseous effluents and finds a large application in industry. The size of the droplet is of fundamental importance to the performance of the equipment. This work aims at studying the effect of some design parameters, namely liquid flow rate and liquid injection system in the droplet size and to correlate this with collection efficiency. A laser diffraction technique was used in order to measure droplet size in situ in a rectangular Venturi scrubber, with liquid injected through 1mm diameter orifices on the throat walls. Liquid flow rates of 600 and 900 ml/min and number of orifices varying from 1 to 5 were used in the experiments. The throat gas velocity was kept at 69.3 m/s. It was found that all these variables significantly affected droplet size. The results of droplet size were compared with the particle capture (collection) efficiency measured in the same experimental conditions. It was observed that the collectio...
A Pease-Anthony Venturi scrubber is a relatively simple and very efficient device used for gas cl... more A Pease-Anthony Venturi scrubber is a relatively simple and very efficient device used for gas cleaning. This paper presents photographic images of the atomization of a liquid jet in the throat of a Pease-Anthony Venturi scrubber, obtained through the development and use of an electronic flash of short duration. This new evidence was used to improve the parameters of the model of Gonçalves et al. (2000) [1]. The experimental conditions used were: throat gas velocities between 59 and 74m/s, jet velocities between 3.18 and 19.10m/s and liquid injected into the throat through different orifices.
Venturi scrubbers are widely utilized in gas cleaning. The cleansing elements in these scrubbers ... more Venturi scrubbers are widely utilized in gas cleaning. The cleansing elements in these scrubbers are droplets formed from the atomization of a liquid into a dust-laden gas. In industrial scrubbers, this liquid is injected through several orifices so that the cloud of droplets can be evenly distributed throughout the duct. The interaction between droplets when injected through many orifices, where opposite clouds of atomized liquid can reach each other, is to be expected. This work presents experimental measurements of droplet size measured in situ and the evidence of cloud interaction within a Venturi scrubber operating with multi-orifice jet injection. The influence of gas velocity, liquid flow rate and droplet size variation in the axial position after the point of the injection of the liquid were also evaluated for the different injection configurations. The experimental results showed that an increase in the liquid flow rate generated greater interaction between jets. The number of orifices had a significant influence on droplet size. In general, the increase in the velocity of the liquid jet and in the gas velocity favored the atomization process by reducing the size of the droplets.
International Journal of Environment and Pollution, 2002
ABSTRACT A survey on the concentration of particulate matter in the urban atmosphere was carried ... more ABSTRACT A survey on the concentration of particulate matter in the urban atmosphere was carried out in the city of Sao Carlos, Brazil. Five sites were selected for data collection one in the city centre (high concentration of people and automotive vehicles), three in industrial areas, and one at the interface with the countryside. The particle size distribution and mass concentration, temperature, humidity and wind velocity were measured at each site. In the city centre, the concentration of the particles smaller than 10 µm (PM<sub align="right"> 10 ) was also measured. The particle size distribution was obtained with a laser scattering particle counter. The total and PM<sub align="right"> 10 concentrations were obtained with high volume samplers. The tests were performed for 75 consecutive weeks. The results show that the particle concentration is sensitive to seasonal conditions. During autumn and winter, which is the drier and windy period of the year, larger particles were dispersed, leading to higher concentrations, both total and PM<sub align="right"> 10 . The relative humidity varied with the schedule of sampling and with the season the autumn and winter weeks were much drier than the other periods. Higher rainfall levels coincided with lower particle concentrations. All these results are statistically significant.
The centrifuge technique was used to investigate the influence of particle size, applied compress... more The centrifuge technique was used to investigate the influence of particle size, applied compression, and substrate material (stainless steel, glass, Teflon, and poly (vinyl chloride)) on particle− surface adhesion force. For this purpose, phosphatic rock (ρp= 3090 kg/m3) ...
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Papers by Jose Coury