Two-dimensional Flow Cell Research Articles

Interfacial turbulence during the physical absorption of carbon dioxide into non-aqueous solvents.

Interfacial turbulence during the physical absorption of CO2 into non-aqueous solvents such as methanol and toluene was investigated experimentally from the point of view of the mass transfer rates. Liquid-phase mass transfer coefficients were measured in the range of gas-liquid contact time t = 0.1-1000 s, using a wetted-wall column, a two-dimensional source flow cell and a quiescent liquid cell, and were compared with calculated values from the penetration theory. The gas-liquid interface during absorption was observed by schlieren photography. It was found that interfacial turbulence owing to the Marangoni effect occurs around t = 0.1 s and succeedingly a density driven convection is superimposed on the turbulence after t = 5-50 s when CO2 is absorbed into non-aqueous (organic) solvents. It is also found that Marangoni-type turbulence occurs in the condition of negative Marangoni number.

Measurement of a Recirculating, Two-Dimensional, Turbulent Flow and Comparison to Turbulence Model Predictions. I: Steady State Case

Turbulent flow measurements have been performed in a two-dimensional flow cell which is a 1/15-scale model of the Fast Flux Test Facility nuclear reactor outlet plenum. In a steady water flow, maps of the mean velocity field, turbulence kinetic energy, and Reynolds stress have been obtained using a laser doppler anemometer. The measurements are compared to numerical simulations using both the K–ε and K–σ two-equation turbulence models. A relationship between K–σ and K–ε turbulence models is derived, and the two models are found to be nearly equivalent. The steady-state mean velocity data are predicted well through-out most of the test cell. Calculated spatial distributions of the scalar turbulence quantities are qualitatively similar for both models; however, the predicted distributions do not match the data over major portions of the flow area. The K–σ model provides better estimates of the turbulence quantity magnitudes. The predicted results are highly sensitive to small changes in the turbulence model constants and depend heavily on the levels of inlet turbulence. However, important differences between prediction and measurement cannot be significantly reduced by simple changes to the model’s constants.