1、Flow electrification by cavity QED,T. V. Prevenslik11F, Greenburg CourtDiscovery Bay, Hong Kong,Contents,Historical backgroundContact electrification PurposeQED Theory Flow analysisConclusions,Historical background,1950 Streaming current Zeta potential induced by impurity ions1980 Electrification de
2、nsity ionic charges as double layer at the wall interface2019 Physiochemical corrosion-oxidation . No evidence of corrosion products Streaming currents shear stress Source never identified,Contact electrification,Contact and Balancing of Fermi levels thermodynamic equilibriumOnly one contact necessa
3、ry for equilibrium - independent of materials.Experiment shows equilibrium is reached in a single contact only for metals - many contacts are necessary to achieve equilibrium between metals and insulators. Some mechanism - in addition to the balancing of Fermi levels - is at play,Cavity QED induced
4、photoelectric effect,Two-step model contact and separation Interface is a high frequency QED cavity that inhibits low frequency IR radiation from thermal kT energy inherent in atomic clusters. IR energy released concentrates to VUV levels in the surfaces of the metal and insulator Electrons are prod
5、uced by the photoelectric effect.,Purpose,Extend the cavity QED induced photoelectric effect in the Two-step model of contact electrification to flow electrification.,Theoretical background,Piping system and laminar flow QED cavities in hydraulic oilsComparison of contact and flow electrificationAva
6、ilable EM energyPhotoelectric effect,Piping system,Hydraulic fluid is pumped in laminar flow through small diameter - long pipe Loop is closed as the fluid falls into an open receiving tank and pumped back to the supply plenum. Air enters the fluid in falling into receiving tank - usually through th
7、e pump .,Air,Air,Laminar flow relations,Velocity,Frictional stress,Pressure,Poiseuille Eqn.,Laminar flow and QED Cavities,Light and electron emission occurs over dimensions from walls less than 100 mmLight emission precedes electron emission - similar to photoelectric effect,QED cavities in hydrauli
8、c oils,Air clusters in flowing hydrocarbon liquidsTearing of oil during flowTearing and QED electrificationSource of EM energy,Air clusters in hydraulic oil,Oil Vapor bubbles Px Pvap Air enters the system through the open tank Solubility of air in hydraulic oils is significant Ostwald coefficient 10
9、 by volume Large air bubbles not likely by surface tension Air dissolved throughout oil as nano- clusters of air ( N2 and O2 molecules ),Tearing of oil during flow,Maximum tension theory Joseph, J Fluid Mech 366 (2019) 367 Cavitation in laminar flow is explained as viscous shear stress produces tens
10、ile stress at 45 to wall Tearing of oil occurs if nominal tensile stress is raised above the rupture stress of oil because of the stress concentration of air clusters Tearing separates oil from itself or boundary wall leaving an evacuated space with oil clusters,Tearing and QED electrification,Teari
11、ng produces vacuum spaces with oil clusters Spaces are a high frequency QED cavities that briefly suppress low frequency IR radiation from oil clusters. Suppressed IR energy loss is conserved by a gain to VUV levels in adjacent oil and wall surfaces Electrons are produced by the photoelectric effect
12、.,Source of EM energy,Oil molecule has thermal kT energyMolecules are harmonic oscillatorsAt ambient temperature, thermal kT energy is equivalent to the molecule emitting IR radiation,Oscillator and IR radiation,At T 300 K, kT0.025 eV Saturation at l 100 mm Most of IR energy in oil molecule occurs:
13、l 20 mm If QED cavity confines IR radiation to l R0 Heptane R0 0.4 mm,IR energy in oil cluster,Spherical cluster energy,VUV energy emitted by cluster,Cavity QED momentarily suppresses IR radiation from clusterConservation of energy requires the prompt release of IR radiationMulti-IR photons combine
14、to VUV levels,Electrons and VIS photons produced,Photoelectric effect,Ndof = 6EVUV = 4.9 eV,Number of VUV photons,Number of electrons,Electron Yield,Flow electrification,Oil clusters and fragments in contact with wall separate at entrance IR radiation is suppressed and released as VUV Electrons are
15、freed from oilWall is charged negative and oil positive,Summary,Flow electrification occurs as oil ruptures in a tearing actionRupture takes place if the tensile stress at a point exceeds the pressure at which the air dissolved in oil, usually atmospheric pressureAir clusters uniformly distributed t
16、hroughout the volume of the oil act as local stress concentrators for ruptureElectron charge Number of oil clusters volumeElectrical current is proportional to volume flow rate Current = Charge density x volume flow rate Current not proportional to surface area of the wall,Flow Analysis,Streaming cu
17、rrent I Re x - flow experiment I A( Px - Patm ) - electrical analogy,NeQ replaces the flow Q Ne is the electron density Since Ne NOC Px-1 Nc Px-1,- Poiseiulle,Volumetric current density,Total current,Conclusions,Flow and contact electrification obey the same physics - Inhibited IR to VUV by cavity Q
18、ED QED cavity is an evacuated space containing oil clusters that briefly forms as the oil ruptures and tears under tensile stressTearing is governed by the tensile stress given by the maximum tension theory Cavity QED converts thermal kT energy to VUV The analytical I and I / Q relations derived are reasonable approximations of flow electrification data for a volume charge relation. An area charge relation does not correlate with the data,END,
