Schematic representation of the measurement system. Design of helical capacitance sensor for holdup measurement in two phase stratified flow. These parameters include the temporal and local variation of void fraction and phase redistribution. A capacitance sensor for twophase void fraction measurement and. Instead of suppressing nonlinear response, the sensor was optimized in such a way that a sinelike function was displayed on top of the linear function.
For the purpose of objective flow pattern identification, a capacitance sensor was developed for horizontal twophase flow in small diameter tubes. The capacitance relationship is illustrated with the following equation. To overcome this limitation, we develop a twophase flow coupled crm model that couples the pressure equation fluid continuity equation and the saturation equation oil mass balance. Preliminary results obtained with a 12electrode system are displayed. The first ecp qualification step is the characterization of the sensor for singlephase conditions. Measurement of gasliquid twophase flow in micropipes by. The exhaust gas composition was assessed by a sickmaihak s. Twophase flow denotes the simultaneous flow of two distinct and immiscible substances and it can be commonly encountered in a wide spectrum of industrial applications, for instance in the transport of oil and gas in pipelines or in the chemical processing industry, where twophase flows occur in reactors, bubble columns and plant components. Electrical capacitance tomography ect is a novel technology that can deal with the complexity of two phase gasoil flow measurement by explicitly deriving the component distributions on two adjacent planes along a pipeline. In this thesis, a novel design of a twophase characterization sensor that measures multiphase flow component fractions is described. Conclusions 15 quickfield was used to optimize and calibrate a capacitance void fraction sensor. A capacitance sensor for twophase liquid film thickness. Two phase flow modelling is strongly dependent on flow patterns. A capacitance sensor is formed by two electrodes of various shapes, usually a fragment of a cylinder, mounted at the outside of the wall of a dielectric pipeline through which a twophase medium flows.
The aim of this paper was to develop a capacitance based sensor capable of measuring void fraction in a continuous twophase flow field. Study of sensor of electrical capacitance tomography ect. Using a composite material analysis and an effective permittivity ratio, predictive relations for capacitance as a function of liquid film thickness. The value of the capacitance is shown using a led interface. In this work, electrical capacitance tomography ect and neural networks were used to automatically identify twophase flow patterns for refrigerant r4a flowing in a horizontal tube. Electrical capacitance tomography twophase oilgas pipe. A capacitance sensor configuration has been designed to characterize horizontal two. However, they require more study before implementation. Void fracti study of void fraction measurement in a two phase flow by using differential pressure and electrical capacitance tomography.
Horizontal twophase flow characterization for small diameter tubes with a capacitance sensor. Capacitive measuring system for twophase flow monitoring 2 fig. A capacitance sensor is formed by two electrodes of various shapes, usually a fragment of a cylinder. As a typical flow regime in a micropipe twophase flow system, slug flow is chosen for this investigation. Twophase, void fraction, capacitance sensor, flow pattern identification. A static twophase pipe flow model made of perspex was used to characterise the sensor. Each single pcb is fabricated thought standard fabrication process. Sensors free fulltext a new capacitance sensor for. In daily life, airconditioning devices are all around us. University of dayton research institute dayton united states personal authors. Capacitance sensors are frequently applied for void fraction measurements in two phase flow. This study examines the velocities of twophase liquidvapor flows with the use of high speed visualization. Gas volumetric flow rate is estimated by crosscorrel. Article simulation analysis of capacitance method in two.
Using this model, different sensor concepts could be tested and the. Void fraction measurement of cryogenic two phase flow. Two laminar twophase flow meter systems were designed and tested. A concave parallel plate capacitance sensor has been developed to measure the twophase flow void fraction for the purpose of objectively identifying flow regimes. A sensor has been developed with a number of requirements with regard to speed and accuracy in mind. By measuring the height at various locations in the channel, the mass flow rate can be calculated. In laboratory experiments, highspeed images were recorded for human classification of liquid.
The design methodology and operation of the capacitance based void fraction sensor is discussed. With a twoplate sensor, the sensor capacitance is the measured variable. This heat transfer is strongly related to the twophase flow patterns. Continuous and precise measurement required for a two phase flow sensor is obtained using the pc connected via rs232 interface. Capacitive sensors are suitable for many applications and its success is. A capacitive sensor has the benefit of being fast and noninvasive. The design methodology of capacitance sensors for voidfraction measurement in adiabatic twophase flow systems is presented in this paper. Then, a horizontal oilwater two phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid. The integrated linearization system ils compensates for influences caused by errors, such as nonparallelism of the plates. Evaluating the two phase flow parameters across tube bundles is crucial to the analysis of vibration excitation mechanisms. Understanding these two phase parameters is essential to evaluating the stability threshold of tube bundle configurations. Any circuit which measures this capacitance will produce a ratio of the sensor capacitance to a discrete circuit element, a fixed capacitor or resistor.
The most common type is the liquidgas twophase flow which is found many. A 360 twisted helical capacitance sensor was developed for holdup measurement in horizontal twophase stratified flow. A concave electrode design with active guarding was chosen. Different configurations of capacitance sensor for gasoil two phase flow measurement. A new capacitance type void fraction sensor was designed, produced, and tested. Many current sensors are dependent on the flow regime of the multiphase stream. Through this coupling, the model parameters such as the connectivity, the time constant, temporal oil saturation, etc.
Exploring capabilities of electrical capacitance tomography sensor and velocity analysis of twophase r4a flow through a sudden expansion descriptive note. Intel 8051 microcontroller based capacitance meter has been developed based on the time lag involved in charging and discharging the capacitor. Horizontal twophase flow occurs widely in the petroleum, nuclear, and chemical industries. Pdf horizontal twophase flow characterization for small. Another important issue on capacitance sensors response influence is the guard electrode. A new method comsol was used to analysis the electrical capacitance tomography of reconstruction image and simulation research. Development of a capacitance based void fraction sensor. Optical techniques laser doppler single phase flows two phase flows 1. By using montecarlo method, the gassolid twophase flow model is established.
Capacitive sensor phasing and ungrounded targets lion. The thickness of the dielectric layer separating the two. This is implemented by measuring the capacitance of the medium inside the acrylic pipeline at two different positions. However, it is difficult for a single method mentioned above to cover all the flow patterns of the twophase flow to. Research of gassolid twophase flow capacitance cross. Evaluating the twophase flow parameters across tube bundles is crucial to the analysis of vibration excitation mechanisms. One of the most common observations in twophase flow is the complete separation between the two phases at moderately low velocities, where such a. Pdf different configurations of capacitance sensor for. Development of a twophase flow coupled capacitance. A sinusoidal function approach article pdf available in sensors 167. Phaseshift detection for capacitance sensor measuring. Capacitance sensors are frequently applied for void fraction measurements in twophase flow. Basics of capacitive sensing and applications davidwang abstract capacitive sensing is becoming a popular technology to replace optical detection methods and mechanical designs for applications like proximitygesture detection, material analysis, and liquid level sensing. Capacitance sensors for voidfraction measurements and.
Technical report,01 jan 2015,30 apr 2017 corporate author. Pi capacitive position sensor electronics incorporate a proprietary design providing superior linearity, low sensitivity to cable capacitance, low background noise and low drift. An online adaptive estimation method for water holdup. Electronic circuit diagram a wave generation circuit, b current generation. Improving the current twophase flow models should therfore focus on incorporating more flow phenomena into the models. Tomographic imaging of twophase flow using capacitance. Two phase or multiphase flows are presented in many process industries such as in our target application, the oil and gas industry. In flow channels where high speed visualization cannot be used, there are other noninvasive techniques for analyzing flow the flow, such as electrical capacitance tomography ect.
Twophase flows experiments in plug, slug, and churn twophase flows show that the probe output signals are consistent with the corresponding flow patterns for plug flow, slug flow, and churn flow. The paper takes gassolid twophase flow crosscorrelation measurement system as the research object, adopts the method of computer simulation to research the measuring mechanism of crosscorrelation velocity. This concept of design had been implemented and verified in both software and hardware. The threeplate sensor can be used for either spacingvariation or areavariation sensors. Twophase flow modelling is strongly dependent on flow patterns. Flow pattern mapping of horizontal evaporating refrigerant. Void fraction measurement a va a capacitance measurement b optical characterization 2. The numerical results agree well with experimental data of airdistilled water towphase flow. A static two phase pipe flow model made of perspex was used to characterise the sensor. Capacitance sensor for void fraction measurement in twophase flow. Understanding these twophase parameters is essential to evaluating the stability threshold of tube bundle configurations.
Highresolution gasoil twophase flow visualization with. Electrical capacitance probe characterization in vertical. With broad application prospects, the purpose of this technique is to identify each phases composition of twophasemultiphase flow system in a closed pipe. Capacitive measurement technique for void fraction. Development of a fastresponse capacitive sensor for two and threephase annularduct flow marlon mauricio hernandez cely supervisor. C capacitance in picofarads k dielectric constant of material a area of plates in square inches d distance between the plates. These issues are discussed, and the design of a 12. To optimize these devices, the prediction of twophase flow heat transfer of evaporating refrigerants has to be improved. Pdf an electrostatic shielding was implemented on capacitance sensor in order to mitigateeliminate external interference.
Pipeline transportation of natural gas in the presence of a liquid phase or mixture of crude oil and water are examples of twophase flow. Study of void fraction measurement in a two phase flow by. For the purpose of objective flow pattern identification, a capacitance sensor was developed for horizontal two phase flow in small diameter tubes. Simple and fast serial analysis using quickfield along with matlab. Local void fractions and bubble velocity in vertical air. Following the sensor verification test using light diesel oil and air, a cryogenic experiment using liquid nitrogen was conducted. Pdf different configurations of capacitance sensor for gasoil two. Pdf design of helical capacitance sensor for holdup.
This sensor applies the difference between the relative permittivity. A capacitance sensor has been developed for measuring timeaveraged void fractions in twophase pipe flow. Pdf capacitance sensor for void fraction measurement in. Electrical capacitance tomography technique is a new technique for multiphase flow measurement. For the typical flow conditions used in this study, the void fractions of the bubbly flow, slug flow, and churn flow were 7. If modelled accurately, the approximation model can be used to calibrate the capacitance sensor to acquire the actual holdup for twophase stratified flow. A capacitive sensor system for the analysis of twophase.
Twophase flow rate measurement using a capacitive sensor and a. Compared with the static numerical simulation, this realtime dynamic 3d simulation method can research on a designed capacitance sensor combining the dynamic characteristics of the twophase flows for. We introduce a gasliquid twophase flow meter which combines a capacitive sensor and a venturi tube. A concave parallel plate capacitance sensor has been developed to measure the two phase flow void fraction for the purpose of objectively identifying flow regimes. A capacitive sensor system for the analysis of twophase flows of oil and conductive water a capacitive sensor system for the analysis of twophase flows of oil and conductive water demori, marco. Experimental studies based on airwater and oilwater twophase stratified flows are carried out to validate the sinusoidal model. Capacitive array sensor for twophase liquid characterization. One of its most promising applications is the visualization of gasoil flows.
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