Distance between nozzles, influence

The influences of the liquid and gas flow rates, the diameter of the absorption chamber, the distance between nozzles, and the flow configuration on absorption rate were studied by the researchers mentioned above. These will not be discussed in detail here because of the length limitation of the chapter for the details, the reader may refer to the original references as cited in the text above. It should be noted, however, that in all the investigations above, the data for mass transfer coefficients are always correlated with the gas and/or liquid flow rates, but not with the impinging velocity, m0, although the latter is the operation parameter extremely important in every impinging stream device. 

The distance between the nozzle and collector has a direct influence on both the flight time and electric field strength. During the electrospinning of polymer... 

Nozzle-Collector Distance—The distance between the nozzle and collector has a direct influence on the flight time of the liquid jet. When a solution is used as the spinning fluid, a minimum nozzle-collector distance is required so the liquid jet can have sufficient time for most of the solvent to be evaporated before reaching the collector. In addition, when the nozzle-collector distance increases, the liquid jet will have a longer distance to travel and this favors the fiber diameter reduction (This applied to both solution and melt). However, when the nozzle-collector distance is too large, the liquid jet may not be able to reach the collector due to the insufficient centrifugal force. 

Various correlations for mean droplet size generated by plain-jet, prefilming, and miscellaneous air-blast atomizers using air as atomization gas are listed in Tables 4.7, 4.8, 4.9, and 4.10, respectively. In these correlations, ALR is the mass flow rate ratio of air to liquid, ALR = mAlmL, Dp is the prefilmer diameter, Dh is the hydraulic mean diameter of air exit duct, vr is the kinematic viscosity ratio relative to water, a is the radial distance from cup lip, DL is the diameter of cup at lip, Up is the cup peripheral velocity, Ur is the air to liquid velocity ratio defined as U=UAIUp, Lw is the diameter of wetted periphery between air and liquid streams, Aa is the flow area of atomizing air stream, m is a power index, PA is the pressure of air, and B is a composite numerical factor. The important parameters influencing the mean droplet size include relative velocity between atomization air/gas and liquid, mass flow rate ratio of air to liquid, physical properties of liquid (viscosity, density, surface tension) and air (density), and atomizer geometry as described by nozzle diameter, prefilmer diameter, etc. 

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