This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe （PWCP）, for two-phase flow measurement. Using finite element method （FEM）, the sensitivity field of the PWCP is investigated and ...This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe （PWCP）, for two-phase flow measurement. Using finite element method （FEM）, the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters. Then, the response of PWCP for the oil-water stratified flow is calculated, and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness, and is almost independant of the angle between the oil-water interface and the sensor electrode. Finally, the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.展开更多
A new capacitance probe is developed for measuring local moisture content in wet porous media. The measurement principle, sensor structure of the probe, dynamic response characteristics and calibration procedure are d...A new capacitance probe is developed for measuring local moisture content in wet porous media. The measurement principle, sensor structure of the probe, dynamic response characteristics and calibration procedure are discussed in detail. The experimental results show that the probe can be used to measure the local moisture content in wet porous media.展开更多
In this letter,the streamer propagation in the atmospheric pressure helium plasma jet with afloating electrode nozzle driven by the kHz AC power supply is investigated.The current signal induced by the space charges a...In this letter,the streamer propagation in the atmospheric pressure helium plasma jet with afloating electrode nozzle driven by the kHz AC power supply is investigated.The current signal induced by the space charges and the mean propagation velocity of the guided ionization waves are measured by the capacitive probe method in the discharge region.The space charges in the guided ionization waves are found to increase with the applied voltage,which enhances both the electric field near the streamer head and the propagation velocity.The applicability of the streamer mechanism to the propagation of the guided ionization waves is validated by this electrical diagnostic method.展开更多
A surface charge measuring system using the capacitive probe method is analysed. The present study shows that the measuring system cannot have a steady-state output and that the error resulting from the finite leakage...A surface charge measuring system using the capacitive probe method is analysed. The present study shows that the measuring system cannot have a steady-state output and that the error resulting from the finite leakage resistance of the measuring system will be accumulated during the measuring process. Based on the theoretical analysis a new type probe with a low charge leakage and high resolution is designed. The surface charge accumulated on the Teflon insulator under a DC voltage is measured using this new probe and some phenomena of the surface charging are reported.展开更多
Supercritical water(SCW)fluidized bed reactors convert biomass to fuels without pollutants emission.In this work,experimental studies were carried out to investigate voidage distribution in an SCW fu-idized bed by cap...Supercritical water(SCW)fluidized bed reactors convert biomass to fuels without pollutants emission.In this work,experimental studies were carried out to investigate voidage distribution in an SCW fu-idized bed by capacitance probes.Quartz sands with different particle sizes were fluidized by SCW under system pressure of 20-27 MPa and temperature of 410-570℃.The effect of operation conditions on voidage distributions of the emulsion phase(e.g.averaged voidage and probability density)is discussed.A predicting correlation between voidage and superficial velocity in emulsion phase is proposed.The relative error of the correlation is within+25%.These research results provide useful guidance for the optimization of supercritical water gasification technology.展开更多
基金Supported by the National Natural Science Foundation of China （50974095, 41174109, 61104148）, and the National Science and Technology Mai or Projects （2011ZX05020-006）.
文摘This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe （PWCP）, for two-phase flow measurement. Using finite element method （FEM）, the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters. Then, the response of PWCP for the oil-water stratified flow is calculated, and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness, and is almost independant of the angle between the oil-water interface and the sensor electrode. Finally, the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.
文摘A new capacitance probe is developed for measuring local moisture content in wet porous media. The measurement principle, sensor structure of the probe, dynamic response characteristics and calibration procedure are discussed in detail. The experimental results show that the probe can be used to measure the local moisture content in wet porous media.
基金supported by National Natural Science Foundation of China(Nos.10775087 and51907190)the State Key Laboratory of NBC Protection for Civilian(SKLNBC 2019–16)。
文摘In this letter,the streamer propagation in the atmospheric pressure helium plasma jet with afloating electrode nozzle driven by the kHz AC power supply is investigated.The current signal induced by the space charges and the mean propagation velocity of the guided ionization waves are measured by the capacitive probe method in the discharge region.The space charges in the guided ionization waves are found to increase with the applied voltage,which enhances both the electric field near the streamer head and the propagation velocity.The applicability of the streamer mechanism to the propagation of the guided ionization waves is validated by this electrical diagnostic method.
基金supported by Science Foundation of Hunan University
文摘A surface charge measuring system using the capacitive probe method is analysed. The present study shows that the measuring system cannot have a steady-state output and that the error resulting from the finite leakage resistance of the measuring system will be accumulated during the measuring process. Based on the theoretical analysis a new type probe with a low charge leakage and high resolution is designed. The surface charge accumulated on the Teflon insulator under a DC voltage is measured using this new probe and some phenomena of the surface charging are reported.
基金This work was financially supported by the National Key R&D Program of China(No.2020YFA0714400)the China National Funds for Distinguished Young Scientists(No.51925602).
文摘Supercritical water(SCW)fluidized bed reactors convert biomass to fuels without pollutants emission.In this work,experimental studies were carried out to investigate voidage distribution in an SCW fu-idized bed by capacitance probes.Quartz sands with different particle sizes were fluidized by SCW under system pressure of 20-27 MPa and temperature of 410-570℃.The effect of operation conditions on voidage distributions of the emulsion phase(e.g.averaged voidage and probability density)is discussed.A predicting correlation between voidage and superficial velocity in emulsion phase is proposed.The relative error of the correlation is within+25%.These research results provide useful guidance for the optimization of supercritical water gasification technology.
