Fluid electrical conductivity

The fluid electrical conductivity a is assumed to be linearly dependent on temperature in all fluid zones and in the membrane as well. The linear law coefficients were fitted on impedance spectroscopy measurements performed over a wide range of temperatures and H2S04 concentrations. The catholyte conductivity is also dependent on the gas volume fraction a2 following the Brugge man relation ... 

Although the fluid electrical conductivity (Aq) depends on the electrolyte concentration and the surface charge density [2, 10] and the surface conductivity (2 ) may vary with the channel size... 

An fuel-air mixture explosion can be initiated by a sudden discharge of static electricity. Yet, while flowing in systems, a fluid develops an electrical charge which will take as long to dissipate as the fluid is a poor conductor. The natural electrical conductivity of jet fuel is very low, on the order of a few picosiemens per meter, and it decreases further at low temperature. 

Hydrocarbons generally have very low electrical conductivities and manipulation of these fluids creates electrostatic charges that can result in fire or explosions. This problem is encountered with gasoline and kerosene. 

Nearly all reservoirs are water bearing prior to hydrocarbon charge. As hydrocarbons migrate into a trap they displace the water from the reservoir, but not completely. Water remains trapped in small pore throats and pore spaces. In 1942 Arch/ e developed an equation describing the relationship between the electrical conductivity of reservoir rock and the properties of its pore system and pore fluids. 

Measurement by Electromagnetic Effects. The magnetic flow meter is a device that measures the potential developed when an electrically conductive flow moves through an imposed magnetic field. The voltage developed is proportional to the volumetric flow rate of the fluid and the magnetic field strength. The process fluid sees only an empty pipe so that the device has a very low pressure drop. The device is useful for the measurement of slurries and other fluid systems where an accumulation of another phase could interfere with flow measurement by other devices. The meter must be installed in a section of pipe that is much less conductive than the fluid. This limits its appHcabiHty in many industrial situations. 

For central station power generation the open cycle system using electrically conducting coal combustion products as the working fluid is employed. The fuel typically is pulverized coal burned directly in the MHD combustor, although in some plant designs cleaner fuels made from coal by gasification or by beneficiation have been considered (8—10) (see Fuels, synthetic). 

Electrical Conductivity. In order to conduct electricity, the working fluid must contain charged particles, ie, it must be partially ionised. 

Magnetic flow meters are sometimes utilized in corrosive Hquid streams or slurries where a low unrecoverable pressure drop and high rangeabiHty is required. The fluid is required to be electrically conductive. Magnetic flow meters, which use Faraday s law to measure the velocity of the electrically conductive Hquid, are relatively expensive. Their use is therefore reserved for special situations where less expensive meters are not appropriate. Installation recommendations usually specify an upstream straight mn of five pipe diameters, keeping the electrodes in continuous contact with the Hquid. 

PCBs and PCTs are particularly troublesome liquids because of their toxicity and persistence in the environment. They are defined as polychlorinated biphenyls, polychlorinated terphenyls, monomethyl-dibromo-diphenyl metliane, monomethyl-dichloro-diphenyl metliane or monomethyl-tetrachlorodiphenyl methane. With low electrical conductivity and heat resistance they found wide use as dielectric fluids and were formerly used as hydraulic fluids. PCBs have not been made in the UK since 1977 and whilst most new uses for the substance are banned in most countries, around two-thirds of the 1.5 million tonnes manufactured in Europe and the US prior to 1985 still remain in equipment such as transformers. PCTs have been used in the past in a restricted range of specialist industrial applications. 

Overbeek and Booth [284] have extended the Henry model to include the effects of double-layer distortion by the relaxation effect. Since the double-layer charge is opposite to the particle charge, the fluid in the layer tends to move in the direction opposite to the particle. This distorts the symmetry of the flow and concentration profiles around the particle. Diffusion and electrical conductance tend to restore this symmetry however, it takes time for this to occur. This is known as the relaxation effect. The relaxation effect is not significant for zeta-potentials of less than 25 mV i.e., the Overbeek and Booth equations reduce to the Henry equation for zeta-potentials less than 25 mV [284]. For an electrophoretic mobility of approximately 10 X 10 " cm A -sec, the corresponding zeta potential is 20 mV at 25°C. Mobilities of up to 20 X 10 " cmW-s, i.e., zeta-potentials of 40 mV, are not uncommon for proteins at temperatures of 20-30°C, and thus relaxation may be important for some proteins. 

While electrical conductivity, diffusion coefficients, and shear viscosity are determined by weak perturbations of the fundamental diffu-sional motions, thermal conductivity is dominated by the vibrational motions of ions. Heat can be transmitted through material substances without any bulk flow or long-range diffusion occurring, simply by the exchange of momentum via collisions of particles. It is for this reason that in liquids in which the rate constants for viscous flow and electrical conductivity are highly temperature dependent, the thermal conductivity remains essentially the same at lower as at much higher temperatures and more fluid conditions. 

A wellbore fluid has been developed that has a nonaqueous continuous liquid phase that exhibits an electrical conductivity increased by a factor of 10 to 10 compared with conventional invert emulsion. 0.2% to 10% by volume of carbon black particles and emulsifying surfactants are used as additives. Information from electrical logging tools, including measurement while drilling and logging while drilling, can be obtained [1563]. 

C. Sawdon, M. Tehrani, and P. Craddock. Electrically conductive non-aqueous wellbore fluids. Patent GB 2345706,2000. 

Other Applications. Thus far the phosphazene fluoroelastomers (PNF) and aryloxyphosphazene elastomers (APN) have moved to the commercial stage. In addition to elastomers, phosphazenes are being investigated as fluids, resins and plastics. Other areas which hold promise include fire resistant paints (55), fiber blends and additives, agrichemicals and herbicides, drug release agents and electrically conducting polymers (6). 

The sensor head is lowered into a monitoring well. Upon contact with any fluid, the float ball is raised and a continuous tone emitted from an audible alarm. When the sensor head contacts the interface between LNAPL and groundwater, the change in conductive properties is detected by the electrical conductivity sensor and a beeping tone is emitted. The distances along the tape at which the two changes in the audible alarm occur are recorded as referenced from a presurveyed point on the lip of the monitoring well. The resultant distance is equivalent to the apparent thickness of the LNAPL in the well. 

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