14 



Film alone 



X, Film Height 

 _D, Diffusivity of Dissolved Gas 



g, Acceleration of Grovity 



V, Kinematic Viscosity 

 -C, Film Widtti 



Q, Flowrote 



I I I \ i 



at which dissolved gas is conveyed past the 



section at x is the width C multiplied by the 



integral in Equation [7]. 



Equation [6] may be integrated by 



methods too detailed to be included here. With 



the aid of Equations [4], [5], and [7], the 



essential result is shown in the form of the 



graph of Figure 6 which allows the estimated 



0.1 0.2 0.3 0.4 0.5 0.6 07 0.8 mixing efficiency to be determined directly 



X a(-V^^ i-Y^^ from the flow rate, chamber dimensions, and 



properties of the fluids. Conversely, the film 

 Figure 6 - Comparison of Observed Mixing ,.,,., ,,, 



„.„" . .,, ... . rpf- :^ „., i?„t;.v,of«^ height which would be necessary to result in 



Efficiency with Mixing Efficiency Estimated & j 



for Vertical Film Alone a given mixing efficiency by exposure in the 

 The solid line indicates the estimated mixing efficien- film alone may be determined. The observed 

 cy for an arrangement in which the exposure of the sam- n^jxing efficiencies for three representative 

 pie water is confined to that provided by the vertical , , i , i 

 ,^ , . conditions are plotted and may be compared 



film which runs down the inside wall of the meter cham- "^ .; i- 



ber. The circles indicate observed mixing efficiencies. with the mixing efficiencies which WOUld have 



This comparison indicates that the exposure provided by jjggjj obtained for the same flow rate and film 



the vertical film is insignificant in the design tested. ,.,..., • i i i ^i /.-i i i 



height if the exposure provided by the film had 

 been the only means of mixing. It is apparent that an insignificant part of the observed ex- 

 posure is attributable to the film. 



A significant difference in mixing efficiency appears between comparable tests with a 

 relatively fine nozzle (Runs 3, 4, and 5) and with a coarse nozzle (Kuns 6, 7, and 8). The 

 difference is in the opposite direction from that which is to be expected if the mixing process 

 depends primarily upon the fineness of the spray. It is believed that the difference in favor 

 of the coarser nozzle is due to the fact that, for a given flow rate, the vertex angle of the 

 conical spray pattern is smaller for the coarser nozzle and that, consequently, a more exten- 

 sive area of emulsion is formed. 



The results of Runs 9, 10, and 11, for which the spray baffle had been installed, show 

 a significant decrease in the mixing efficiency from the values obtained for the three runs 

 immediately previous. The reason for this was apparent: a considerable portion of the flow 

 drained from the top of the chamber down the support of the spray baffle, thus reducing the 

 volume of water supported and agitated by the spray in the form of an emulsion. 



DESCRIPTION OF FINAL DESIGN 



In accordance with observations made during the experiments and with conclusions 

 indicated above, the version of the meter chamber illustrated in Figure 4c was designed. 



As a measure for reducing the response time, provision of a large wall area was aban- 

 doned in favor of minimizing the gas-space volume. This choice follows the conclusion 



