IMPINGING STREAMS measurement

Kostiuk et al. [40] measured experimentally the flow field of the vertical co-axial turbulent impinging streams with a two-component Laser Doppler velocity meter. The opposing gas streams were ejected from two burner nozzles, which were designed to produce a uniform axial velocity profile at their exits. The turbulence in the flow was generated by a perforated plate located at the end of the contraction section in each nozzle. The air velocity at the exit of the nozzle was varied from 4.1 to 11.4 m s and... 

In the investigation by Enyakin the maximum distance of penetration was measured by photographing the trajectories of various kinds of particles in impinging streams and the results obtained are shown in Fig. 2.4 as the plots of the relative penetration depth xmax/

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Using the procedure described above, input a step change of the tracer to the hopper and then measure the response of the screw feeder to the step change as a known function of time, which is used as the input signal to the following impinging stream device for the measurement of RTD. 

A set of typical data calibrated is shown in Fig. 3.7. It demonstrates that there is good regularity and reproducibility of the data, suggesting the calibrated curves can be used as the input signals to the impinging stream device for RTD measurement to yield sufficiently accurate results. 

In the derivation above, the input signal C (t) is an arbitrary function of time, without any restraint condition, but, of course, it should be known CAo is the response of the impinging stream device to CAi(r) that can be measured by sampling at the outlet of the device. 

The pressure drops between Points A and C, between Points A and C, between Points A and B, and between Points A and B , denoted by -ApAC, -ApA C, -ApAB, and -A/Evb, respectively, are measured with inclined U-shape tubes filled with colored kerosene. The average of -ApAB and -ApA B- is taken as the pressure drop through the accelerating pipes, while that of -Ap v and -ApA c as the overall pressure drop across the impinging stream contactor, -ApT. Consequently, there should be... 

As described in Section 4.2, the sub-pressure drop measured between Points B and C or between Points B and C, -ApBC or -APb o is the sum of the pressure drop across the impingement zone, —Apim, and the structural resistance -A/ ds, but not any individual one of them. Such a measuring arrangement is not only because the pressure fluctuation frequently occurs round the impingement zone, making accurate measurement difficult, but also because both sub-pressure drops are too small (< 10 Pa) to be measured separately. To obtain the values for these sub-pressure drops, Eq. (4.17) can be specified for the impinging stream contactor studied here as... 

A comparison between the data measured for the overall pressure drop across the impinging stream contactor and the corresponding values calculated with Eq. (4.25) is illustrated in Fig. 4.6. Good agreement between the results measured and calculated can be observed clearly, suggesting that the total pressure drop model established is reasonable and feasible for application. In addition, it has the advantages of universal applicability and convenience in calculation. 

Figure 5.1 Impinging stream device for the measurement of droplet size distribution. 1 critical nozzle 2, 3 rotameter 4 frame 5 guider 6 apron A-A impingement plane.

It is actually very difficult to obtain representative and reproducible data for the size distribution of sprayed droplets, no matter what kind of method is employed for measurement, because the dispersion of liquid by atomization, including re-atomization in impinging streams, is highly random. In the study the following factors are considered carefully in the arrangement of sampling for representative samples and thus statistically trustworthy results ... 

Obviously, mass transfer coefficient is a topic of general interest. Tamir, Herskowits et at. [59, 106, 107, 109] studied experimentally the absorption of C02 and acetone into water in a two impinging stream absorber operated in various modes with various atomizers. The data they measured for the volumetric mass transfer coefficient are listed in Table 7.2, which are representative among earlier investigations. 

With the impinging velocity u0 ranging from 5.53 to 16.62 m s 1, the measured volumetric mass transfer coefficient kGa is in the range 0.577 to 1.037 s 1 and kG from 0.00641 to 0.0416 m-s 1, showing clearly the effect of gas-continuous impinging streams enhancing mass transfer ... 

For comparison, the experiments for measuring the overall crystal-growth rate coefficient are carried out in an impinging stream crystallizer (ISC) and a fluidized bed crystallizer (FBC). 

Except for a few questionable data, the values for the observed active energy measured in the two crystallizers of different types, EiS and EFB, show little difference and can be considered to be more or less identical. On the other hand, the values measured in the impinging stream crystallizer for the overall crystal-growth rate coefficient, KIS, are obviously and systematically larger than those in the fluidized bed crystallizer, A pe. Therefore it can be affirmed without the need for further analysis that, with the observed frequency factors, there must... 

Once they have left the separation system the ions will meet the ion trap or detector which, in the simplest instance, will be in the form of a Faraday cage (Faraday cup). In any case the ions which impinge on the detector will be neutralized by electrons from the ion trap. Shown, after electrical amplification, as the measurement signal itself is the corresponding ion emission stream . To achieve greater sensitivity, a secondary electron multiplier pickup (SEMP) can be employed in place of the Faraday cup. 

It is found from experimental measurements that the pressure drop caused by the impingement between the opposing streams is independent of the presence of particles. 

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