Mass transfer from a solid sphere to water in highly turbulent flow

Abstract

Mass transfer coefficients from +-in. spheres of benzoic and cinnamic acids and 2-napthol to water were measured in the high Reynolds number region of 600 to 140,000. Previous data for liquids extended only to a Reynolds number of 11,000. Three separate and approximately parallel lines of JD vs. Reynolds number were found for the different solutes, and the shape of the curves was found to be similar to the total-drag-coefficient correlation for spheres.Experiments with benzoic acid and 2-napthol showed an effect of driving force and hence dux on the JD values. Mass transfer did occur in saturated solutions having zero driving force. When one subtracted the amount of mass transfer at zero driving force from the values at other driving forces, the corrected JD values at different driving forces were the same for a given solute. Possible explanations may be the effect of extreme turbulence on crystallization or physical attrition. In the present experimental work, %-in. spheres of benzoic and cinnamic acids and 2-naphthol were used, and mass transfer coefficients were measured a t a Reynolds number between 600 and 140,000. The effects of mass flux and Schmidt number were also investigated. LITERATURE REVIEW AND THEORYIn mass transfer from dissolving solids t o flowing liquids the driving force is assumed to be the saturation solubility Linton and Sherwood ( 7 ) determined JD values for individual benzoic acid spheres for a Reynolds number range of 1,500 to 11,000. The spheres were mounted in the center of the pipe and supported by a metal wire normal to the flow. Data were also obtained for transverse cylinders with rinnamic and benzoic acids, with the JD for benzoic acid being approximately 20% higher than for cinnamic acid.McCune and Wilhelm (8) used a 2-naphtho1 pellet which was resting on a wire screen, up through which the liquid flowed. Data were obtained for a Reynolds number range of 30 to 500, in which the pellet was essentially immobile on the screen.Garner and Suckling ( 5 ) determined JD values for single spheres of adipic and benzoic acids for a Reynolds number range of 30 to 700. The spheres were supported by an axial rod on the downstream side. They correlated their data and those of Garner and Grafton ( 4 ) and found that for Reynolds niimbers greater than 100 above the natural-convection regionDryden, Strang, and U'ithrow ( 3 ) found that at Reynolds numbers below 10 in packed beds values of J D for benzoic acid were greater than for 2-naphthol.Goldstein (6) discussed the drag on a sphere and stated that spheres supported Fig. 1. Cinnamic acid sphere after a run. by a cross wire will disturb the flow continuity over the sphere surface and give a total drag up t o double that when the sphere is held a t the back by an axial spindle. He gives a plot of total drag vs. Reynolds number values up to 4,000,000.At low Reynolds numbers the drag coefficient decreases with increasing Reynolds numbers and levels off in the Reynolds number region of 5,000 to 250,000. Then the drag coefficient suddenly drops over...

Molecular Diffusion Coefficients of Organic Compounds in Water at Different Temperatures

“…In all cases, diffusion coefficients increase with increasing temperature, as expected. Ghosh et al [7] Sahay et al [9] Dunker [6] Steele and Geankoplis [11] Wilke and Chang [18] Seidell [10] c* (kg/m 3 ) = 1. [12][13][14][15][16][17] at different temperatures, and this is an indication of the accuracy of the proposed method.…”

Low Reynolds Number Mass Transfer in Packed Beds of Cylindrical Particles

“…The relevant physical properties at the average temperature of a run were evaluated from the respective graphs prepared on the basis of the reported values. Solubility data for benzoic acid for this purpose were those reported by Seidel (1941), Seidel and Linke (1952), Steele and Geankoplis (1959), and Stephen and Stephen (1963). Molecular diffusivities were calculated by Wilke-Chang's (1955) relation and are listed in Table II.…”

Laminar Flow Dissolution and Diffusion in Non-Newtonian Fluid

“…The saturation solubilities of benzoic acid in aqueous CMC solution were those reported earlier (51). Solubility and viscosity data for water were taken from the literature (51)(52)(53)(54)(55)(56). The physical properties for the systems are listed in Table I.…”