Equivalent circulating density

More rapid drilling (slim holes, optimised bit choice, good hydraulics and mud design) reduces shale exposure time. Since all of the diffusive processes are time-dependent, instability is less commonly observed, and slim holes are inherently easier to drill. However, the hydraulic system must be studies to insure adequate hole cleaning without excessive flow pressure effects (called equivalent circulating density effects in the oil industry). 

DDBSA dodecyl benzene sulfonic acid ECD equivalent circulating density... 

The scaling law proposed by Horio for circulating fluidized beds can be shown to be equivalent to the simplified set of parameters. Horio also discussed reductions to his list of scaling parameters in which the solid/gas density ratio is omitted. He claimed that this reduced scaling law... 

Sodium orthoarsenate is also obtained electrolytically by the method described under calcium arsenate (p. 198). Yields up to 100 per cent, may be obtained 9 by employing a cell with a diaphragm between iron electrodes. The anolyte should contain sodium arsenite, or sodium hydroxide and arsenious oxide (equivalent to 150 g. As2Os per litre), and the catholyte sodium hydroxide (150 g. per litre). With a current density of 3 amps, per sq. dm. the current efficiency is 100 per cent. A solid crust of sodium arsenate forms around the anode. The process may be rendered continuous by circulating the anolyte and removing the precipitated arsenate. Iron or nickel electrodes are... 

Gas Bubbles Fluid particles, unlike rigid solid particles, may undergo deformation and internal circulation. Figure 6-59 shows rise velocity data for air bubbles in stagnant water. In the figure, Eo = Eotvos number, g(pL - pG)dJa, where pL = liquid density pG = gas density, de = bubble diameter, a = surface tension, and the equivalent diameter de is the diameter of a sphere with volume equal to that of... 

For BH3 the single p-electron defines the special z direction. For paired spins this direction must coincide with a B-H bond. The three H atoms can therefore not be equivalent and the most likely H(s)(sp)B(sp)(s)H linear array has an unpaired s electron on B that interacts with the third H atom which is smeared out along an equatorial annulus that defines the overlap of the circulating H(ls) density with the B(2s) shell. 

If the rate of desorption of surfactants is very much greater than the rate at which the drop traverses through a distance equivalent to its diameter (about 0.02 sec), one may expect (D6) no accumulation of surfactants at the rear end. A quantitative semiempirical expression for the degree of drop circulation as a function of the viscous forces, drop diameter, densities and the compressional modulus of the surface film (surface-tension gradient), as well as the empirical fraction of liquid circulating, has been suggested by Davies (D6). 

Equation E21.1.5 for the current density for the reaction is the electrochemical equivalent of the rate equation for a conventional reaction. We now solve this equation simultaneously with the reactor equation for the selected reactor, for example. Equation 21.46 for a conventional BR with circulation operated as a PFR, or Equation 21.51 for a BR with circulation operated as a CSTR. Thus the electrode area A. can be estimated as a function of conversion Af, [/4]f, current density a, and reaction time t, t- All electrochemical parameters of the equations can be experimentally determined from polarization studies, The reactor efficiency can then be obtained from ( a and i. ... 

The power density of the reactor core is typically lower in a natural circulation reactor than in a forced circulation reactor, but the lower power density allows a longer continuous operation. The short heated length of the fuel and the low power density provide good thermal-hydraulic characteristics. With the 8 x g type fuel assembly selected, the power density is 34.2 kW/L the number of fuel assemblies is 708, and the equivalent core diameter is 4.65 m. The uranium enrichment of the refuelling batch, at equilibrium, is 3.6%, and the average fuel burn-up is 39 GWd/t for operation cycles of 23 months. 

Boundary conditions were set as follows room temperature of 293 K (20°C) in each part of the facility and atmospheric pressure of 1 bar. The level in the pools is at the elevation of 10 m, which is the equivalent of 2.85 m measured from the bottom of the pool. The initial velocity of the fluid is 0 m/s everywhere in the facility. The input heating power was 99 kW in equal radial distribution in the 3 heated channels of the core. Upper plenum was filled with water totally. Table II shows the performed scenarios and status of the isolation valves. The initial condition of the experiments did not fully correspond the condition of the reference reactor in a LOCA situation after the depressurization period. The initial temperature is close to room temperature when density differences, which create the natural circulation, doesn t exist yet. 

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