However, they require more study before implementation. Pi capacitive position sensor electronics incorporate a proprietary design providing superior linearity, low sensitivity to cable capacitance, low background noise and low drift. Capacitive sensor phasing and ungrounded targets lion. Tomographic imaging of twophase flow using capacitance. The rules of 12electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance and sensitivity map the basis of airwater two phase flow permittivity. A static twophase pipe flow model made of perspex was used to characterise the sensor. Capacitance sensor for void fraction measurement in twophase flow. 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. As a typical flow regime in a micropipe twophase flow system, slug flow is chosen for this investigation. Development of a capacitance based void fraction sensor.
Capacitive sensors are suitable for many applications and its success is. If modelled accurately, the approximation model can be used to calibrate the capacitance sensor to acquire the actual holdup for twophase stratified flow. Pdf horizontal twophase flow characterization for small. Flow pattern mapping of horizontal evaporating refrigerant. This experimental study uses electrical capacitance tomography ect technique for measuring the void fraction in two phase bubble flow regime. Measurement of gasliquid twophase flow in micropipes by. Pdf design of helical capacitance sensor for holdup. Twophase flow modelling is strongly dependent on flow patterns. Finite element simulations were made for optimizing the design. One of the most common observations in twophase flow is the complete separation between the two phases at moderately low velocities, where such a. A capacitance sensor is formed by two electrodes of various shapes, usually a fragment of a cylinder. In laboratory experiments, highspeed images were recorded for human classification of liquid.
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. The first ecp qualification step is the characterization of the sensor for singlephase conditions. A capacitance sensor configuration has been designed to characterize horizontal two. Local void fractions and bubble velocity in vertical air. We introduce a gasliquid twophase flow meter which combines a capacitive sensor and a venturi tube. A new capacitance type void fraction sensor was designed, produced, and tested. 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. Research of gassolid twophase flow capacitance cross. Electrical capacitance probe characterization in vertical. Microcontroller based capacitance meter for a two phase.
Evaluating the two phase flow parameters across tube bundles is crucial to the analysis of vibration excitation mechanisms. Schematic representation of the measurement system. However, it is difficult for a single method mentioned above to cover all the flow patterns of the twophase flow to. Development of a fastresponse capacitive sensor for two and threephase annularduct flow marlon mauricio hernandez cely supervisor. Conclusions 15 quickfield was used to optimize and calibrate a capacitance void fraction sensor. A sensor has been developed with a number of requirements with regard to speed and accuracy in mind. One of its most promising applications is the visualization of gasoil flows. Electrical capacitance tomography twophase oilgas pipe. Study of void fraction measurement in a two phase flow by. Understanding these two phase parameters is essential to evaluating the stability threshold of tube bundle configurations.
A sinusoidal function approach article pdf available in sensors 167. Horizontal twophase flow characterization for small diameter tubes with a capacitance sensor. The threeplate sensor can be used for either spacingvariation or areavariation sensors. To optimize these devices, the prediction of twophase flow heat transfer of evaporating refrigerants has to be improved. For the purpose of objective flow pattern identification, a capacitance sensor was developed for horizontal two phase flow in small diameter tubes. Another important issue on capacitance sensors response influence is the guard electrode. Capacitive measuring system for twophase flow monitoring 2 fig. 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.
A capacitance sensor for twophase liquid film thickness. 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. Simple and fast serial analysis using quickfield along with matlab. C capacitance in picofarads k dielectric constant of material a area of plates in square inches d distance between the plates. Capacitance sensors are frequently applied for void fraction measurements in two phase flow. Pdf different configurations of capacitance sensor for. Technical report,01 jan 2015,30 apr 2017 corporate author. Sensors free fulltext a new capacitance sensor for. A capacitance sensor has been developed for measuring timeaveraged void fractions in twophase pipe flow. Void fraction measurement a va a capacitance measurement b optical characterization 2. Two phase or multiphase flows are presented in many process industries such as in our target application, the oil and gas industry. These parameters include the temporal and local variation of void fraction and phase redistribution. 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. A capacitive sensor has the benefit of being fast and noninvasive.
In this thesis, a novel design of a twophase characterization sensor that measures multiphase flow component fractions is described. For the purpose of objective flow pattern identification, a capacitance sensor was developed for horizontal twophase flow in small diameter tubes. This sensor applies the difference between the relative permittivity. Evaluating the twophase flow parameters across tube bundles is crucial to the analysis of vibration excitation mechanisms. An online adaptive estimation method for water holdup. The numerical results agree well with experimental data of airdistilled water towphase flow. Using this model, different sensor concepts could be tested and the. 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. 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. These issues are discussed, and the design of a 12. Two phase flow modelling is strongly dependent on flow patterns. The design methodology of capacitance sensors for voidfraction measurement in adiabatic twophase flow systems is presented in this paper. Twophase, void fraction, capacitance sensor, flow pattern identification. Article simulation analysis of capacitance method in two.
The capacitance relationship is illustrated with the following equation. The aim of this paper was to develop a capacitance based sensor capable of measuring void fraction in a continuous twophase flow field. Twophase flow rate measurement using a capacitive sensor and a. Experimental studies based on airwater and oilwater twophase stratified flows are carried out to validate the sinusoidal model. With broad application prospects, the purpose of this technique is to identify each phases composition of twophasemultiphase flow system in a closed pipe. For the typical flow conditions used in this study, the void fractions of the bubbly flow, slug flow, and churn flow were 7. Continuous and precise measurement required for a two phase flow sensor is obtained using the pc connected via rs232 interface. This study examines the velocities of twophase liquidvapor flows with the use of high speed visualization.
Highresolution gasoil twophase flow visualization with. 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. 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. Improving the current twophase flow models should therfore focus on incorporating more flow phenomena into the models. Horizontal twophase flow occurs widely in the petroleum, nuclear, and chemical industries. Design of helical capacitance sensor for holdup measurement in two phase stratified flow. The exhaust gas composition was assessed by a sickmaihak s. University of dayton research institute dayton united states personal authors. The effect of design parameters on the capacitance output has been theoretically and experimentally investigated for two types of sensor configurations. Pdf different configurations of capacitance sensor for gasoil two.
The most common type is the liquidgas twophase flow which is found many. The thickness of the dielectric layer separating the two. In daily life, airconditioning devices are all around us. Many current sensors are dependent on the flow regime of the multiphase stream. A concave electrode design with active guarding was chosen. The design methodology and operation of the capacitance based void fraction sensor is discussed. 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. Study of sensor of electrical capacitance tomography ect. The value of the capacitance is shown using a led interface. 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. Phaseshift detection for capacitance sensor measuring. Using a composite material analysis and an effective permittivity ratio, predictive relations for capacitance as a function of liquid film thickness. A capacitance sensor for twophase void fraction measurement and. By measuring the height at various locations in the channel, the mass flow rate can be calculated.
Different configurations of capacitance sensor for gasoil two phase flow measurement. Intel 8051 microcontroller based capacitance meter has been developed based on the time lag involved in charging and discharging the capacitor. By using montecarlo method, the gassolid twophase flow model is established. Following the sensor verification test using light diesel oil and air, a cryogenic experiment using liquid nitrogen was conducted. Two laminar twophase flow meter systems were designed and tested. Each single pcb is fabricated thought standard fabrication process.
Pipeline transportation of natural gas in the presence of a liquid phase or mixture of crude oil and water are examples of twophase flow. Preliminary results obtained with a 12electrode system are displayed. A static two phase pipe flow model made of perspex was used to characterise the sensor. A new method comsol was used to analysis the electrical capacitance tomography of reconstruction image and simulation research. This is implemented by measuring the capacitance of the medium inside the acrylic pipeline at two different positions. Electronic circuit diagram a wave generation circuit, b current generation. The integrated linearization system ils compensates for influences caused by errors, such as nonparallelism of the plates.
Capacitive measurement technique for void fraction. A 360 twisted helical capacitance sensor was developed for holdup measurement in horizontal twophase stratified flow. If the targetground capacitance is considerably larger than the probetarget capacitance 100 times, the total change in resistance to the current flow is negligible and. Optical techniques laser doppler single phase flows two phase flows 1. Capacitance sensors are frequently applied for void fraction measurements in twophase flow. Capacitance sensors for voidfraction measurements and. 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. Exploring capabilities of electrical capacitance tomography sensor and velocity analysis of twophase r4a flow through a sudden expansion descriptive note. This concept of design had been implemented and verified in both software and hardware. The concept involves vaporliquid twophase flow through narrow, parallel channels which results in a laminar, stratified flow with a slope at the liquidvapor interface. A capacitive sensor system for the analysis of twophase. Understanding these twophase parameters is essential to evaluating the stability threshold of tube bundle configurations.
Electrical capacitance tomography technique is a new technique for multiphase flow measurement. The working principles and the configurations of instruments for void fraction measurements, flow visualization and velocity measurements are presented. A capacitance measurement system is developed for the measurement of gasliquid twophase flow in glass micropipes with inner diameters of 3. Void fraction measurement of cryogenic two phase flow. Any circuit which measures this capacitance will produce a ratio of the sensor capacitance to a discrete circuit element, a fixed capacitor or resistor. Void fracti study of void fraction measurement in a two phase flow by using differential pressure and electrical capacitance tomography. Pdf an electrostatic shielding was implemented on capacitance sensor in order to mitigateeliminate external interference. A concave parallel plate capacitance sensor has been developed to measure the twophase flow void fraction for the purpose of objectively identifying flow regimes. This heat transfer is strongly related to the twophase flow patterns. Multielectrode capacitance sensors for the visualization of transient twophase flows multielectrode capacitance sensors for the visualization of transient twophase flows reinecke, n mewes, d.
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. With a twoplate sensor, the sensor capacitance is the measured variable. Gas volumetric flow rate is estimated by crosscorrel. Development of a twophase flow coupled capacitance. Pdf capacitance sensor for void fraction measurement in.1649 1653 500 450 689 32 1289 404 1654 550 1359 372 427 1186 549 1178 1102 208 634 1601 1626 1417 1556 256 1202 953 1143 1224 13 1053 1396 709