Airflow Rate

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Peter Demeyer - One of the best experts on this subject based on the ideXlab platform.

  • Effect of sampling density on the reliability of Airflow Rate measurements in a naturally ventilated animal mock-up building
    Energy and Buildings, 2017
    Co-Authors: Gerlinde De Vogeleer, Jan Pieters, Philippe Van Overbeke, Peter Demeyer
    Abstract:

    Abstract Measuring natural ventilation Rates in buildings with large vents with high accuracy and precision is not straight forward due to high spatial and temporal variabilities in the velocity distribution. Simplification of Airflow Rate measurements are mostly effectuated by lowering sampling density. Different sampling densities were investigated for both direct and tracer gas methods and compared with a detailed direct measurement method were in a naturally ventilated animal mock-up building. The results obtained by the reference method indicated that using only sampling locations in the middle of the side openings overestimated the Airflow Rate. In view of wind variations, better accuracy, precision and lower coefficients of variation were obtained with a higher number of sampling locations. The coefficients of variation varied between 5% for the reference and 29% using only one sampling location in the side outlet. In the ridge opening, only one middle sampling location was sufficient for an accuracy of 2% and a precision of 3%. The indirect tracer gas method gave varying concentrations with high confidence intervals resulting in non-significantly different measurement results between the different sampling stRategies. The pattern of sampling locations was found to be very important resulting in different accuracies for a given sampling density.

  • Methodology for Airflow Rate measurements in a naturally ventilated mock-up animal building with side and ridge vents
    Building and Environment, 2016
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Eva Brusselman, Peter Demeyer, Luciano Barreto Mendes, J.g. Pieters
    Abstract:

    Currently there exists no generally accepted reference technique to measure the ventilation Rate through naturally ventilated (NV) vents. This has an impact on the reliability of Airflow Rate control techniques and emission Rate measurements in NV animal houses. As an attempt to address this issue a NV test facility was built to develop new Airflow Rate measurement techniques for both side wall and ridge vents. Three set-ups were used that differed in vent configuration, i.e. one cross ventilated set-up and two ridge ventilated set-ups with different vent sizes. The Airflow through the side vents was measured with a technique based on an automatic traverse movement of a 3D ultrasonic anemometer. In the ridge, 7 static 2D ultrasonic anemometers were installed. The methods were validated by applying the air mass conservation principle, i.e. the inflow Rates must equal the outflow Rates. The calculated in - and outflow Rates agreed within (5 +/- 8)%, (8 +/- 5)% and (-9 +/- 7)% for the three different set-ups respectively, over a large range of wind incidence angles. It was found that the side vent configuration was of large importance for the distribution of the Airflow Rates through the vents. The ridge proved to be a constant outlet, whilst side vents could change from outlet to inlet depending on the wind incidence angle. The range of wind incidence angles in which this transition occurred could be clearly visualized.

  • Assessing Airflow Rates of a naturally ventilated test facility using a fast and simple algorithm supported by local air velocity measurements
    Building and Environment, 2016
    Co-Authors: G. De Vogeleer, P. Van Overbeke, Eva Brusselman, Jan Pieters, Luciano Barreto Mendes, Peter Demeyer
    Abstract:

    Abstract The high spatial and temporal variations of Airflow patterns in ventilation openings of naturally ventilated animal houses make it difficult to accuRately measure the Airflow Rate. This paper focusses on the development of a fast assessment technique for the Airflow Rate of a naturally ventilated test facility through the combination of a linear algorithm and local air velocity measurements. This assessment technique was validated against detailed measurement results obtained by the measuring method of Van Overbeke et al. (2015) as a reference. The total air velocity | U ¯ | , the normal | Y ¯ | and tangential velocity component | X ¯ | and the velocity vector U ¯ measured at the meteomast were chosen as input variables for the linear algorithms. The Airflow Rates were split in a group where only uni-directional flows occurred at vent level (no opposite directions of | Y ¯ | present in the Airflow pattern of the opening), and a group where bi-directional flows occurred (the air goes simultaneously in and out of the opening). For Airflow Rates with uni-directional flows the input variables U ¯ and | Y ¯ | yielded the most accuRate results. For this reason, it was suggested to use the | Y ¯ | instead of | U ¯ | in ASHRAE’s formula of Q = E × A × | U ¯ | . For bi-directional flows a multiple linear model was suggested where input variable U ¯ gave the best results to assess the Airflow Rate.

  • Development of a reference method for Airflow Rate measurements through rectangular vents towards application in naturally ventilated animal houses
    Computers and Electronics in Agriculture, 2015
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Eva Brusselman, Jan Pieters, Peter Demeyer
    Abstract:

    A naturally ventilated test facility was built.An Airflow Rate measuring method using 3D ultrasonic anemometers was developed.The method was successfully validated through the law of mass conservation.The effect of the wind incidence angle and speed on the Airflow Rate was studied.The necessity of measuring the 3D in-/outflow pattern was proven. In order to measure the Airflow Rate and emission Rate of a naturally ventilated livestock building correctly, more reliable measuring techniques need to be developed. A test facility with a cross ventilated room was built at the Institute for Agricultural and Fisheries Research (Belgium) to study a new Airflow Rate measuring method. This method is based on an automated traverse movement of a 3D ultrasonic anemometer across 2 vents of 0.5mi?1.0m. To cope with the fluctuating wind velocity profile, a velocity measurement of 10s in 16 equally distributed measuring points is needed. Moreover, 10 traverse replicates are needed to obtain a representative average flow Rate. Based on the law of mass conservation, the accuracy of the method was determined by calculating the relative deviation between the simultaneously measured Airflow Rates through both vents. A relative error of -1?11% was found, averaged over all wind incidence angles. However, wind angles parallel to the vent resulted in larger relative errors. A 3D velocity measurement in the in- or outlet opening of the test facility is necessary to obtain a correct flow Rate. This was especially true in the outlet where up to 30% of the Airflow Rate was delivered by velocity components other than normal to the vent. The test facility and the developed ventilation Rate measuring method can serve as a reference to study and validate new and existing ventilation Rate measuring methods.

  • Development of a reference method for Airflow Rate measurements through rectangular vents towards application in naturally ventilated animal houses: Part 2: Automated 3D approach
    Computers and Electronics in Agriculture, 2014
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Jan Pieters, Peter Demeyer
    Abstract:

    An accuRate measurement of the Airflow Rate in a naturally ventilated animal house is still an issue due to the large uncertainties of the available techniques. These uncertainties are mainly related to the variability of the velocity profile in a naturally ventilated opening caused by, among others, fluctuations in wind direction and speed. An experimental set-up was built to develop Airflow Rate measurement methods which can cope with these different profiles and can be further developed for future use in naturally ventilated openings. The methods were compared to a reference technique for mechanical ventilation (VDI2041) as no such reference exists for natural Airflows. A relative measurement error from this reference of max. 10% was deemed acceptable. The methods were based on a fully automated traverse movement of respectively a 2D and a 3D ultrasonic anemometer behind the outlet of two different rectangular ducts (respectively 1m and 3m wide). Several Airflow Rates were imposed, combined with disturbances of the Airflow to obtain different velocity profiles. Measurements performed with a 2D ultrasonic anemometer gave rise to relatively high measurement errors (up to -18%) related to the 3D character of the outflow jet. Two methods were developed with a 3D ultrasonic sensor in order to capture the outflow characteristics more adequately. The Basic method concentRated on the area in front of the outlet, while an Extended method paid more attention to the Airflow around the edges of the outlet. Both methods succeeded in keeping the relative measurement error below the 10% limit, and even below 5% error for the 3m wide duct. For future use in naturally ventilated openings, more research is necessary to further adapt the methods to continuously changing conditions of wind speed and direction.

M. Ben Amor - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Airflow Rate and substRate nature on heterogeneous struvite precipitation
    Environmental technology, 2009
    Co-Authors: Hassidou Saidou, S. Ben Moussa, M. Ben Amor
    Abstract:

    In wastewater treatment plants a hard scale consisting of struvite crystals can be formed, in pipes and recirculation pumps, during anaerobic digestion of wastewater. This study was conducted to evaluate the effect of Airflow Rate and substRate nature on nucleation type, induction period and supersaturation coefficient during struvite precipitation. A crystallization reactor similar to that designed for calcium carbonate precipitation was used. The pH of synthetic wastewater solution was increased by air bubbling. Experimental results indicated that the Airflow increased heterogeneous precipitation of struvite. The susceptibility to scale formation was more important on polyamide and polyvinyl chloride than on stainless steel. In all cases, X‐ray diffraction and infrared spectroscopy showed that the precipitated solid phase was solely struvite. No difference in crystal morphology was observed. However, at similar experimental conditions, the particle size of struvite was higher for stainless‐steel materia...

  • Struvite precipitation by the dissolved CO2 degasification technique: impact of the Airflow Rate and pH.
    Chemosphere, 2008
    Co-Authors: Hassidou Saidou, Atef Korchef, S. Ben Moussa, M. Ben Amor
    Abstract:

    Abstract In the present work, struvite precipitation was provoked by the dissolved CO2 degasification technique where precipitation occurred following the degassing of the CO2 by atmospheric air. The impact of the Airflow Rate and initial solution pH on struvite precipitation were assessed. For initial solution pH   6.5, the phosphorus removal through struvite precipitation could be improved by increasing the Airflow Rate up to 25 L min−1, or by increasing the initial pH for higher Airflow Rates. Compared to traditional techniques of struvite precipitation such as stirring and aeration, the dissolved CO2 degasification technique is promising since a high amount of phosphorus (∼78%) could be removed at relatively short experiment time.

P. Van Overbeke - One of the best experts on this subject based on the ideXlab platform.

  • Methodology for Airflow Rate measurements in a naturally ventilated mock-up animal building with side and ridge vents
    Building and Environment, 2016
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Eva Brusselman, Peter Demeyer, Luciano Barreto Mendes, J.g. Pieters
    Abstract:

    Currently there exists no generally accepted reference technique to measure the ventilation Rate through naturally ventilated (NV) vents. This has an impact on the reliability of Airflow Rate control techniques and emission Rate measurements in NV animal houses. As an attempt to address this issue a NV test facility was built to develop new Airflow Rate measurement techniques for both side wall and ridge vents. Three set-ups were used that differed in vent configuration, i.e. one cross ventilated set-up and two ridge ventilated set-ups with different vent sizes. The Airflow through the side vents was measured with a technique based on an automatic traverse movement of a 3D ultrasonic anemometer. In the ridge, 7 static 2D ultrasonic anemometers were installed. The methods were validated by applying the air mass conservation principle, i.e. the inflow Rates must equal the outflow Rates. The calculated in - and outflow Rates agreed within (5 +/- 8)%, (8 +/- 5)% and (-9 +/- 7)% for the three different set-ups respectively, over a large range of wind incidence angles. It was found that the side vent configuration was of large importance for the distribution of the Airflow Rates through the vents. The ridge proved to be a constant outlet, whilst side vents could change from outlet to inlet depending on the wind incidence angle. The range of wind incidence angles in which this transition occurred could be clearly visualized.

  • Assessing Airflow Rates of a naturally ventilated test facility using a fast and simple algorithm supported by local air velocity measurements
    Building and Environment, 2016
    Co-Authors: G. De Vogeleer, P. Van Overbeke, Eva Brusselman, Jan Pieters, Luciano Barreto Mendes, Peter Demeyer
    Abstract:

    Abstract The high spatial and temporal variations of Airflow patterns in ventilation openings of naturally ventilated animal houses make it difficult to accuRately measure the Airflow Rate. This paper focusses on the development of a fast assessment technique for the Airflow Rate of a naturally ventilated test facility through the combination of a linear algorithm and local air velocity measurements. This assessment technique was validated against detailed measurement results obtained by the measuring method of Van Overbeke et al. (2015) as a reference. The total air velocity | U ¯ | , the normal | Y ¯ | and tangential velocity component | X ¯ | and the velocity vector U ¯ measured at the meteomast were chosen as input variables for the linear algorithms. The Airflow Rates were split in a group where only uni-directional flows occurred at vent level (no opposite directions of | Y ¯ | present in the Airflow pattern of the opening), and a group where bi-directional flows occurred (the air goes simultaneously in and out of the opening). For Airflow Rates with uni-directional flows the input variables U ¯ and | Y ¯ | yielded the most accuRate results. For this reason, it was suggested to use the | Y ¯ | instead of | U ¯ | in ASHRAE’s formula of Q = E × A × | U ¯ | . For bi-directional flows a multiple linear model was suggested where input variable U ¯ gave the best results to assess the Airflow Rate.

  • Development of a reference method for Airflow Rate measurements through rectangular vents towards application in naturally ventilated animal houses
    Computers and Electronics in Agriculture, 2015
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Eva Brusselman, Jan Pieters, Peter Demeyer
    Abstract:

    A naturally ventilated test facility was built.An Airflow Rate measuring method using 3D ultrasonic anemometers was developed.The method was successfully validated through the law of mass conservation.The effect of the wind incidence angle and speed on the Airflow Rate was studied.The necessity of measuring the 3D in-/outflow pattern was proven. In order to measure the Airflow Rate and emission Rate of a naturally ventilated livestock building correctly, more reliable measuring techniques need to be developed. A test facility with a cross ventilated room was built at the Institute for Agricultural and Fisheries Research (Belgium) to study a new Airflow Rate measuring method. This method is based on an automated traverse movement of a 3D ultrasonic anemometer across 2 vents of 0.5mi?1.0m. To cope with the fluctuating wind velocity profile, a velocity measurement of 10s in 16 equally distributed measuring points is needed. Moreover, 10 traverse replicates are needed to obtain a representative average flow Rate. Based on the law of mass conservation, the accuracy of the method was determined by calculating the relative deviation between the simultaneously measured Airflow Rates through both vents. A relative error of -1?11% was found, averaged over all wind incidence angles. However, wind angles parallel to the vent resulted in larger relative errors. A 3D velocity measurement in the in- or outlet opening of the test facility is necessary to obtain a correct flow Rate. This was especially true in the outlet where up to 30% of the Airflow Rate was delivered by velocity components other than normal to the vent. The test facility and the developed ventilation Rate measuring method can serve as a reference to study and validate new and existing ventilation Rate measuring methods.

  • Development of a reference method for Airflow Rate measurements through rectangular vents towards application in naturally ventilated animal houses: Part 2: Automated 3D approach
    Computers and Electronics in Agriculture, 2014
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Jan Pieters, Peter Demeyer
    Abstract:

    An accuRate measurement of the Airflow Rate in a naturally ventilated animal house is still an issue due to the large uncertainties of the available techniques. These uncertainties are mainly related to the variability of the velocity profile in a naturally ventilated opening caused by, among others, fluctuations in wind direction and speed. An experimental set-up was built to develop Airflow Rate measurement methods which can cope with these different profiles and can be further developed for future use in naturally ventilated openings. The methods were compared to a reference technique for mechanical ventilation (VDI2041) as no such reference exists for natural Airflows. A relative measurement error from this reference of max. 10% was deemed acceptable. The methods were based on a fully automated traverse movement of respectively a 2D and a 3D ultrasonic anemometer behind the outlet of two different rectangular ducts (respectively 1m and 3m wide). Several Airflow Rates were imposed, combined with disturbances of the Airflow to obtain different velocity profiles. Measurements performed with a 2D ultrasonic anemometer gave rise to relatively high measurement errors (up to -18%) related to the 3D character of the outflow jet. Two methods were developed with a 3D ultrasonic sensor in order to capture the outflow characteristics more adequately. The Basic method concentRated on the area in front of the outlet, while an Extended method paid more attention to the Airflow around the edges of the outlet. Both methods succeeded in keeping the relative measurement error below the 10% limit, and even below 5% error for the 3m wide duct. For future use in naturally ventilated openings, more research is necessary to further adapt the methods to continuously changing conditions of wind speed and direction.

G. De Vogeleer - One of the best experts on this subject based on the ideXlab platform.

  • Methodology for Airflow Rate measurements in a naturally ventilated mock-up animal building with side and ridge vents
    Building and Environment, 2016
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Eva Brusselman, Peter Demeyer, Luciano Barreto Mendes, J.g. Pieters
    Abstract:

    Currently there exists no generally accepted reference technique to measure the ventilation Rate through naturally ventilated (NV) vents. This has an impact on the reliability of Airflow Rate control techniques and emission Rate measurements in NV animal houses. As an attempt to address this issue a NV test facility was built to develop new Airflow Rate measurement techniques for both side wall and ridge vents. Three set-ups were used that differed in vent configuration, i.e. one cross ventilated set-up and two ridge ventilated set-ups with different vent sizes. The Airflow through the side vents was measured with a technique based on an automatic traverse movement of a 3D ultrasonic anemometer. In the ridge, 7 static 2D ultrasonic anemometers were installed. The methods were validated by applying the air mass conservation principle, i.e. the inflow Rates must equal the outflow Rates. The calculated in - and outflow Rates agreed within (5 +/- 8)%, (8 +/- 5)% and (-9 +/- 7)% for the three different set-ups respectively, over a large range of wind incidence angles. It was found that the side vent configuration was of large importance for the distribution of the Airflow Rates through the vents. The ridge proved to be a constant outlet, whilst side vents could change from outlet to inlet depending on the wind incidence angle. The range of wind incidence angles in which this transition occurred could be clearly visualized.

  • Assessing Airflow Rates of a naturally ventilated test facility using a fast and simple algorithm supported by local air velocity measurements
    Building and Environment, 2016
    Co-Authors: G. De Vogeleer, P. Van Overbeke, Eva Brusselman, Jan Pieters, Luciano Barreto Mendes, Peter Demeyer
    Abstract:

    Abstract The high spatial and temporal variations of Airflow patterns in ventilation openings of naturally ventilated animal houses make it difficult to accuRately measure the Airflow Rate. This paper focusses on the development of a fast assessment technique for the Airflow Rate of a naturally ventilated test facility through the combination of a linear algorithm and local air velocity measurements. This assessment technique was validated against detailed measurement results obtained by the measuring method of Van Overbeke et al. (2015) as a reference. The total air velocity | U ¯ | , the normal | Y ¯ | and tangential velocity component | X ¯ | and the velocity vector U ¯ measured at the meteomast were chosen as input variables for the linear algorithms. The Airflow Rates were split in a group where only uni-directional flows occurred at vent level (no opposite directions of | Y ¯ | present in the Airflow pattern of the opening), and a group where bi-directional flows occurred (the air goes simultaneously in and out of the opening). For Airflow Rates with uni-directional flows the input variables U ¯ and | Y ¯ | yielded the most accuRate results. For this reason, it was suggested to use the | Y ¯ | instead of | U ¯ | in ASHRAE’s formula of Q = E × A × | U ¯ | . For bi-directional flows a multiple linear model was suggested where input variable U ¯ gave the best results to assess the Airflow Rate.

  • Development of a reference method for Airflow Rate measurements through rectangular vents towards application in naturally ventilated animal houses
    Computers and Electronics in Agriculture, 2015
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Eva Brusselman, Jan Pieters, Peter Demeyer
    Abstract:

    A naturally ventilated test facility was built.An Airflow Rate measuring method using 3D ultrasonic anemometers was developed.The method was successfully validated through the law of mass conservation.The effect of the wind incidence angle and speed on the Airflow Rate was studied.The necessity of measuring the 3D in-/outflow pattern was proven. In order to measure the Airflow Rate and emission Rate of a naturally ventilated livestock building correctly, more reliable measuring techniques need to be developed. A test facility with a cross ventilated room was built at the Institute for Agricultural and Fisheries Research (Belgium) to study a new Airflow Rate measuring method. This method is based on an automated traverse movement of a 3D ultrasonic anemometer across 2 vents of 0.5mi?1.0m. To cope with the fluctuating wind velocity profile, a velocity measurement of 10s in 16 equally distributed measuring points is needed. Moreover, 10 traverse replicates are needed to obtain a representative average flow Rate. Based on the law of mass conservation, the accuracy of the method was determined by calculating the relative deviation between the simultaneously measured Airflow Rates through both vents. A relative error of -1?11% was found, averaged over all wind incidence angles. However, wind angles parallel to the vent resulted in larger relative errors. A 3D velocity measurement in the in- or outlet opening of the test facility is necessary to obtain a correct flow Rate. This was especially true in the outlet where up to 30% of the Airflow Rate was delivered by velocity components other than normal to the vent. The test facility and the developed ventilation Rate measuring method can serve as a reference to study and validate new and existing ventilation Rate measuring methods.

  • Development of a reference method for Airflow Rate measurements through rectangular vents towards application in naturally ventilated animal houses: Part 2: Automated 3D approach
    Computers and Electronics in Agriculture, 2014
    Co-Authors: P. Van Overbeke, G. De Vogeleer, Jan Pieters, Peter Demeyer
    Abstract:

    An accuRate measurement of the Airflow Rate in a naturally ventilated animal house is still an issue due to the large uncertainties of the available techniques. These uncertainties are mainly related to the variability of the velocity profile in a naturally ventilated opening caused by, among others, fluctuations in wind direction and speed. An experimental set-up was built to develop Airflow Rate measurement methods which can cope with these different profiles and can be further developed for future use in naturally ventilated openings. The methods were compared to a reference technique for mechanical ventilation (VDI2041) as no such reference exists for natural Airflows. A relative measurement error from this reference of max. 10% was deemed acceptable. The methods were based on a fully automated traverse movement of respectively a 2D and a 3D ultrasonic anemometer behind the outlet of two different rectangular ducts (respectively 1m and 3m wide). Several Airflow Rates were imposed, combined with disturbances of the Airflow to obtain different velocity profiles. Measurements performed with a 2D ultrasonic anemometer gave rise to relatively high measurement errors (up to -18%) related to the 3D character of the outflow jet. Two methods were developed with a 3D ultrasonic sensor in order to capture the outflow characteristics more adequately. The Basic method concentRated on the area in front of the outlet, while an Extended method paid more attention to the Airflow around the edges of the outlet. Both methods succeeded in keeping the relative measurement error below the 10% limit, and even below 5% error for the 3m wide duct. For future use in naturally ventilated openings, more research is necessary to further adapt the methods to continuously changing conditions of wind speed and direction.

Manuel Mota - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Airflow Rate on yields of Steinernema carpocapse Az 20 in liquid culture in an external-loop airlift bioreactor.
    Biotechnology and bioengineering, 2001
    Co-Authors: José Manuel Neves, José A. Teixeira, Nelson Simões, Manuel Mota
    Abstract:

    Maximization of the contact between males and females is a key factor in the production of the nematode Steinernema carpocapsae in a bioreactor.%The influence of the Airflow Rate in male and female distribution and mass production in an external-loop bioreactor with a deceleration zone was studied. When operating at an Airflow Rate of 0.05 vvm, a high retention of females in the deceleration zone of the bioreactor was observed and a larger nematode productivity was obtained. At this aeration Rate there was a higher proportion of males in that zone, which together with the lower circulation Rate, increases the probability of encounters, thereby explaining the increase in productivity. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 72: 369–373, 2001.

  • COMMUNICATION TO THE EDITOR Effect of Airflow Rate on Yields of Steinernema carpocapse Az 20 in Liquid Culture in an External-Loop Airlift Bioreactor
    2001
    Co-Authors: Manuel Mota
    Abstract:

    Maximization of the contact between males and females is a key factor in the production of the nem- atode Steinernema carpocapsae in a bioreactor. The influence of the Airflow Rate in male and female distribution and mass production in an external-loop bio- reactor with a deceleration zone was studied. When op- erating at an Airflow Rate of 0.05 vvm, a high retention of females in the deceleration zone of the bioreactor was observed and a larger nematode productivity was ob- tained. At this aeration Rate there was a higher propor- tion of males in that zone, which together with the lower circulation Rate, increases the probability of encounters, thereby explaining the increase in productivity. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 72: 369-373, 2001.