A novel technique for determining mass transfer coefficients in agitated solid‐liquid systems

Abstract

This paper presents the results of an experimental investigation in which boiling heat transfer data for Freon 1 1 and Freon 113 refrigerants were obtained. The experimental apparatus used for the investigation i s described. Forced convection boiling heat fluxes, heat transfer coefficients, and pressure drops were determined. The effects of mass flow rate, evaporation pressure, liquid film superheat, and exit vapor Reynolds number are presented. The coefficient CSF, appearing in Rohsenow's correlation for nucleate boiling, i s determined for both fluids in stainless steel and copper tubes. Two-phase flow pressure drops ore presented for both refrigerants as a function of mass flow rate and exit quality. l I ~ ~ ~ ~ Abstract: The mixing characteristics for combinations of plates ond downcomers for Glitsch V-1 ballast trays were determined with a three-plate column that was 27 in. in diameter. The mixing could be described by an eddy diffusion model. Far combinations of plates and downcomers, the eddy diffusivity was found to be a function of the mean-linear velocity of the liquid and independent of the physical properties of the liquid as well as the gas flow rate throughout the range of liquid and gas flow rates employed in the investigation. A variety of liquids were used and the Peclet numbers ranged from 4.4 to 27. Enthalpy values for hypothetical fluids from vapor-liquid equilibrium data, Welker, A c = concentration of dichromate = total solids area, sq. cm.ion, g. moles/cc.Abstract: Graphite oxidation studies have been carried out in oxygen and in air between 400" and 530°C. An analytical system capable of detecting product carbon dioxide and carbon monoxide at concentrations less than 10 parts/million was developed and used during the work. Kinetic results are compared with literature data obtained under similar conditions. The effect of bulk and surface properties of the graphite on oxidation rate and product distribution is considered. A reaction mechanism is proposed which reconciles much of the published data and the results reported herein.The roles of capillary wicking and surface deposits in the attainment of high pool boiling burnout heat fluxes, Costello, C. P., and W.

Mass Transfer Characteristics during the Removal of Dissolved Heavy Metals from Waste Solutions in Gas Sparged Fluidized Beds of Ion Exchange Resins

“…For the batch gas-sparged reactor used in the present work, the rate of diffusion-controlled reaction at the surface of the resin particles can be expressed in terms of the disappearance of cupric ions from the solution by the equation [28] The observed increase in the mass transfer coefficient with increasing superficial gas velocity may be attributed to the following effects:…”

Effect of surfactants on the rate of diffusion‐controlled Cementation of copper from dilute solutions on a stationary zinc disc in stirred vessels

“…The rate of diffusion-controlled cementation of copper on zinc can be expressed in terms of the disappearance of cupric ions from the solution by the equation [21] which upon integration yields Figure 1 shows a typical In C,/C versus t plot. The mass transfer coefficient, K, of the cementation process was determined under different conditions from the slope In CJC versus t lines.…”

Liquid–solid mass transfer behaviour of a fixed bed airlift reactor

“…Abdel-Aziz et al [1] using electrochemical technique studied the mass transfer behaviour of the wall of the downcomer of a concentric tube airlift reactor with the aim of using airlift reactors for conducting diffusion controlled gas-liquid-solid electrochemical reactions and developing a heat transfer equation (by analogy) which predicts the rate of heat transfer to a cooling jacket surrounding the reactor. The present study was conducted using a technique which involves the diffusion controlled dissolution of copper in acidified dichromate [29,30], the technique has been used widely to study liquid-solid mass transfer in view of its simplicity and accuracy [31][32][33][34][35]. The technique does not suffer from the drawback of the benzoic acid technique which produces exaggerated mass transfer coefficient owing to particle attrition, the present (1) Air-lift reactor, (2) nitrogen gas cylinder, (3) pressure regulator with screwdown valve, (4) calibrated rotameter, (5) 8 mm PVC tubing, (6) non-return valve, (7) G2 sintered glass gas sparger, (8) liquid level in the air-lift reactor, (9) riser, (10) downcomer, (11) insulated stainless steel support, (12) Raschig rings fixed bed, (13) insulated stainless steel strainer, (14) baffle, (15) drain valve.…”