Resistance due to structure of the device

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 

for each experimental run, the pressure drop across the impingement zone, -Apim, can be obtained from the average value of measured -ApBc and -ApB c and the value of -Apds calculated with Eq. (4.22) as its indirectly measured value  

By way of illustration, two sets of indirectly measured data for the pressure drop across the impingement zone are listed in Table 4.2. 

As can be seen from the table, the mass flow rate ratio m m, has no effect on -Apim, and the equivalent local resistance coefficient jm calculated with Eq. (4.13) is essentially kept constant. This implies that the pressure drop across the impingement zone is independent of the presence of particles. The value for averaged over a total of 490 sets of data is equal to 0.096. So, the pressure drop across the impingement zone can be calculated with the relationship below  

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