Effective particle concentration

The collection efficiency of the wire-plate-type of electrostatic precipitator can be estimated by the widely used Deutsch theory [Deutsch, 1922]. To obtain the Deutsch equation, the following assumptions are made (1) because of the turbulent mixing effect, particle concentration at any cross section of the precipitator is uniformly distributed ... 

Compared to conventional microsized filler particles used in the foaming processes, nanoparticles offer unique advantages for enhanced nucleation. The extronely fine dimensions and large surface area of nanoparticles provide much more mtimate contact between the fillers, polymer matrix, and gas. Furthermore, a significantly higher effective particle concentration can be achieved at a low nominal particle concentration. Both could lead to improved nucleation efficiency. 

The effect of nanoparticle dispersion on the foam cell morphology is readily understood by the nucleation theories described above (Equation 1.1). As nanoparticles were better dispersed, higher effective particle concentration would have been achieved at the same nominal concentration. However, dispersion is critically important in obtaining good foam morphology. If the nanoparticle dispersion is not sufficient, nonuniform cellular structure may result (Manninen et al., 2005). 

This effect of concentration is particularly pronounced with irregularly shaped particles. A possible explanation of the variation in the specific resistance is in terms of the time available for the particles to orient themselves in the growing cake. At higher concentrations, but with the same approach velocities, less time, referred to as particle relaxation time, is available for a stable cake to form and a low resistance results. 

Doppler Flow Meters. Doppler flow meters sense the shift in apparent frequency of an ultrasonic beam as it is reflected from air bubbles or other acoustically reflective particles that ate moving in a Hquid flow. It is essential for operation that at least some particles ate present, but the concentration can be low and the particles as small as ca 40 p.m. CaUbration tends to be influenced by particle concentration because higher concentrations result in mote reflections taking place neat the wall, in the low velocity portion of the flow profile. One method used to minimize this effect is to have separate transmitting and receiving transducers focused to receive reflections from an intercept zone neat the center of the pipe. 

Hindered Settling When particle concentration increases, particle settling velocities decrease oecause of hydrodynamic interaction between particles and the upward motion of displaced liquid. The suspension viscosity increases. Hindered setthng is normally encountered in sedimentation and transport of concentrated slurries. Below 0.1 percent volumetric particle concentration, there is less than a 1 percent reduction in settling velocity. Several expressions have been given to estimate the effect of particle volume fraction on settling velocity. Maude and Whitmore Br. J. Appl. Fhys., 9, 477—482 [1958]) give, for uniformly sized spheres,... 

This, in turn, reduced the number of polymer particles (the loci of reaction) and hence the reaction rate fell. However, this explanation is at variance with the results reported in Figure 12 where the molecular weight (weight-average) clearly increases with increasing Reynolds number. It seems more likely that the turbulent flow results could be explained by a decrease in the effective initiator concentration. This low concentration would also explain why there is no further reaction after a period of about one hour as contrasted with the batch reactions where the reaction is still proceeding after two to three hours. The current absence of corroborating evidence makes this explanation very tentative. 

It can be seen from Fig. 35(c) that MRR increases continuously with the solid concentration, which is consentaneous with the former results [41,106]. This may be due to the stronger mechanical grinding effect at the high particle concentration at which particles impact and grind the surfaces. 

As indicated above, there is a relationship between particle concentration, equilibrium factor and the amount of highly mobile radioactive particles. Removal of the accumulation mode particles may decrease the decay product exposure, but increase the dose because of the high effectiveness of the "unattached activity in dose deposition. Thus, air cleaning may not succeed in lower risk unless both factors are taken into account. Jonassen explores electrostatic filtration in this context. Finally, design considerations are presented for a possible alternative control system using activated carbon in an alternating bed system. 

Here we have only discussed the concentration of the radon gas. This is because the measurements have been made of this nuclide. However, the health effects are referred to the short-lived decay products. The equilibrium factor depends on the ventilation rate and the particle concentrations. 

Comparison of our theory with experimental data shows excellent agreement, both with respect to the molecular weight dependency and to the effect of particle radius and particle concentration. 

The next problem is to find an expression for Asg. This entropy difference is a function of the particle volume fractions in the dispersion ( ) and in the floe (<(> ). As a first approximation, we assume that Ass is independent of the concentration and chain length of free polymer. This assumption is not necessarily true the floe structure, and thus < >f, may depend on the latter parameters because also the solvent chemical potential in the solution (affected by the presence of polymer) should be the same as that in the floe phase (determined by the high particle concentration). However, we assume that these effects will be small, and we take as a constant. 

The added mass force accounts for the resistance of the fluid mass that is moving at the same acceleration as the particle. Neglecting the effect of the particle concentration on the virtual-mass coefficient, for a spherical particle, the volume of the added mass is equal to one-half of the particle volume, so that... 

On the reverse, how does the presence of particles affect local and global flow features in the vessel such as the vortex structure in the vicinity of the impeller, power consumption, circulation and mixing times, and the spatial distribution of turbulence quantities more specifically colliding particles have an impact on the liquid s turbulence (Ten Cate et al., 2004) while local particle concentrations affect the effective (slurry) viscosity which may be useful in the macroflow simulations ... 

This additional Eq. (18) was discretized at the same resolution as the flow equations, typical grids comprising 1203 and 1803 nodes. At every time step, the local particle concentration is transported within the resolved flow field. Furthermore, the local flow conditions yield an effective 3-D shear rate that can be used for estimating the local agglomeration rate constant /10. Fig. 10 (from Hollander et al., 2003) presents both instantaneous and time-averaged spatial distributions of /i0 in vessels agitated by two different impellers color versions of these plots can be found in Hollander (2002) and in Hollander et al. (2003). 

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