J. Krabicka

University of Kent, Cantorbery, England, United Kingdom

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Publications (16)4.07 Total impact

  • Xinli Li, Duo Sun, Gang Lu, Jan Krabicka, Yong Yan
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    ABSTRACT: The characteristics of reacting radicals in a flame are crucial for an in-depth understanding of the formation process of combustion emissions. This paper presents an algorithm for the prediction of NOx (NO and NO2) emissions in flue gas through flame radical imaging, flame temperature monitoring and application of Neural Network techniques. Radiation images of flame radicals OH*, CN*, CH* and C2* are captured using an intensified multi-wavelength imaging system. Flame temperature is determined using a spectrometer and two-color pyrometry. Based on these images, the characteristic values of the flame radicals are extracted. These characteristic values, together with the flame temperature, are then used to predict NOx emissions. Experimental results from a laboratory-scale gas-fired combustion rig have shown the effectiveness of the proposed method for the prediction of NOx emissions.
    IEEE International Conference on Imaging Systems and Techniques, Manchester, UK; 07/2012
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    J. Krabicka, Gang Lu, Yong Yan
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    ABSTRACT: This paper presents the development of an instrumentation system for visualizing and characterizing free radicals in combustion flames. The system combines optical splitting, filtering, intensified imaging and image processing techniques for simultaneous and continuous monitoring of specific flame radicals ( OH*, CN*, CH*, and C<sub>2</sub>*). Computing algorithms are developed to analyze the images and quantify the radiative characteristics of the radicals. Experimental results are obtained from a gas-fired combustion rig to demonstrate the effectiveness of the system. The information obtained by the system is used to establish relationships between radical characteristics and air-to-fuel ratios of combustion gases, helping to obtain an in-depth understanding of burn characteristics.
    IEEE Transactions on Instrumentation and Measurement 06/2011; · 1.36 Impact Factor
  • J. Krabicka, Gang Lu, Yong Yan
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    ABSTRACT: This paper presents the development of an instrumentation system for visualizing and characterizing free radicals in combustion flames. The system combines optical splitting and filtering, intensified imaging and image processing techniques, providing a solution for the monitoring of flame radicals (OH*, CN*, CH*, and C<sub>2</sub>*) simultaneously and continuously. Computing algorithms are developed to analyze the images and quantify the radiative characteristics of the radicals. Experimental results are obtained from a gas-fired combustion rig to demonstrate the effectiveness of the system. The information obtained by the system can be used to establish the relationships between radical characteristics and the chemical and physical properties of the fuels and combustion products, helping to obtain an in-depth understanding of pollutant formation processes, and leading to an optimized combustion process.
    Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE; 06/2010
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    ABSTRACT: Accurate strip speed measurement is desirable in certain manufacturing industries. This paper presents the recent development in the non-contact measurement of strip speed using electrostatic sensors in conjunction with correlation signal processing techniques. A pair of narrow strip electrodes is used to derive signals from a moving solid surface. The speed of the solid surface is then determined from the known spacing between the electrodes and the time delay between the two signals. Experimental tests were conducted on a motorized cable speed test rig under a range of conditions. An optical tachometer was used as a reference instrument to assess the accuracy of the new strip speed measurement system. Basic sensor design considerations and the advantages and limitations of the method are addressed. Results demonstrate that the technique is capable of measuring strip speed with a relative error no greater than ±1.5% and a repeatability of better than 2%.
    Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE; 06/2010
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    Jiaqing Shao, Jan Krabicka, Yong Yan
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    ABSTRACT: This paper reports recent developments of electrostatic sensors for the continuous velocity measurement of particles in pneumatic conveying pipelines. The optimization of intrusive electrostatic sensors is investigated through finite-element modeling and experimental evaluation. The effects of electrode dimensions and intrusion depth on sensor signals and correlation-based velocity measurement are addressed. The modeling results were validated for a range of velocity profiles using a dedicated belt rig, which produces idealized particle flow. A series of online experimental tests using circular and rod electrodes was conducted on an industrial-scale pneumatic conveyor injecting pulverized coal and biomass particles. The results demonstrate that electrostatic sensors are capable of providing reliable velocity measurement of pneumatically conveyed particles with excellent repeatability and fast dynamic response in an industrial environment.
    IEEE Transactions on Instrumentation and Measurement 01/2010; 59:1477-1484. · 1.36 Impact Factor
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    J Krabicka, G Lu
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    ABSTRACT: Combustion flames contain strong emissions from excited radical species produced by the combustion process. The monitoring and characterisation of such emissions is important for an in-depth understanding of fuel energy conversion and pollutant formation processes. In this paper, an approach combining emission spectroscopy with intensified digital imaging techniques is proposed for visualising and quantifying the radiative characteristics of free radicals of combustion flames. Recent advances in CCD technology, especially in EM image intensification, have made it possible to obtain high resolution emission images of isolated spectral emissions from particular flame radicals. These can be used to study emission intensity and distribution, with the aim of correlating combustion emission products with flame spectral emission patterns.
    Journal of Physics Conference Series 07/2009; 178(1):012041.
  • J. Krabicka, Yong Yan
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    ABSTRACT: This paper reports recent advances in the optimisation of intrusive electrostatic sensors for the continuous velocity measurement of particles in pneumatic conveying pipelines. The effects of electrode dimensions and intrusion depth on sensor signals and correlation based velocity measurement have been investigated. Different cross sectional shapes of the electrodes have been compared. The optimum intrusion depth for a velocity measurement closest to the true mean velocity in a pipeline with a given velocity profile is established.
    Instrumentation and Measurement Technology Conference, 2009. I2MTC '09. IEEE; 06/2009
  • Jiaqing Shao, Yong Yan, J. Krabicka
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    ABSTRACT: This paper presents the latest development in the velocity measurement of pulverized coal and biomass fuels in pneumatic pipelines using electrostatic sensors in combination with correlation signal processing techniques. A comparative study of electrostatic sensors with circular and rod electrodes was conducted on a 94mm bore horizontal pipeline feeding a 4 MW industrial scale furnace. Experimental tests were conducted under coal/biomass co-firing conditions for different proportions between the two fuels. The advantages and limitations of the two different sensor electrodes are addressed. Experimental results demonstrate that both sensors are capable of providing pulverized fuel velocity measurement with excellent repeatability and fast dynamic response under an industrial environment.
    Instrumentation and Measurement Technology Conference, 2009. I2MTC '09. IEEE; 06/2009
  • R.M. Carter, J. Krabicka, Y. Yan, S. Cornwell
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    ABSTRACT: The instrumentation technologies required to achieve optimized combustion in pulverized fuel power plants represent an important challenge under increasing economical and environmental pressures. The present paper reports on the final results of a British government funded project to bring together various new and emerging sensing technologies aimed at achieving this goal. Both fuel flow and burner conditions are monitored. The former are studied here through electrostatic velocity metering and non-invasive imaging based particle sizing. For the latter flame stability monitoring and on-line fuel tracking are achieved by analyzing optical signals received from the flames. Details of individual technologies employed are introduced and power plant trials and some results are presented. In general the integrated instrumentation system has performed well during plant trials. The unique combination of novel technologies employed represents an important step forward in this area.
    Instrumentation and Measurement Technology Conference, 2009. I2MTC '09. IEEE; 06/2009
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    Y Yan, RM Carter, J Krabicka, S Cornwell
    British-French Flame Days, Lille,; 01/2009
  • Jan Krabicka, Yong Yan
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    ABSTRACT: Electrostatic sensors are used in certain industries for the flow measurement of pneumatically conveyed solids. However, despite various advances that have been made in recent years, relatively little information is known about the exact nature of the electrostatic charge induced onto the sensor electrode due to moving particles, which is dependent on electrode geometry, particle distribution, and particle velocity. This paper presents a novel approach to the study of the charge induced onto electrostatic sensors based on fitting a Lorentzian curve to the results of a finite-element model of the electrostatic sensor and pipeline. The modeling method is validated by comparing the modeling results of a nonintrusive circular electrode with an established analytical solution. The modeling results are used for in-depth analysis and informed design of a particular sensor configuration.
    IEEE Transactions on Instrumentation and Measurement 01/2009; 58:2730-2736. · 1.36 Impact Factor
  • J. Krabicka, Yong Yan
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    ABSTRACT: Electrostatic sensors are used in the power generation industry to measure the velocity and other parameters of pulverized fuel. However, relatively little is known about the exact nature of the signal induced onto the sensor electrode, which is dependent on sensor geometry, particle size distribution, and particle velocity. This paper presents a novel approach to the study of signals induced onto intrusive electrostatic sensors, based on fitting a Lorentzian curve to the results of a finite element model of the sensor and pipeline.
    Instrumentation and Measurement Technology Conference Proceedings, 2007. IMTC 2007. IEEE; 06/2007
  • Jiaqing Shao, Jan Krabicka, Yong Yan
    仪器仪表学报. 01/2007;
  • International Conference on Coal Combustion Science and Technology; 01/2007
  • J Krabicka, Y Yan, RM Carter
    01/2006;
  • J Krabicka, RM Carter, Y Yan
    01/2006;