Countercurrent exchange

About: Countercurrent exchange is a research topic. Over the lifetime, 2255 publications have been published within this topic receiving 28687 citations. The topic is also known as: Countercurrent exchange.

Theoretical analysis of interfacial instability in countercurrent annular two-phase flow

Abstract: The instability of a liquid-gas interface in countercurrent annular two-phase flow is studied with a small disturbance analysis; the curvature of the interface and the viscosity and velocity distributions in liquid and gas phases are necessarily taken into account. This analysis indicates that the average velocity, velocity distribution, and viscosity of liquid film affect the instability criterion significantly. Comparison of the present analysis with analyses by Hewitt and Imura, in which the viscous effect was neglected, indicates that viscosity produces two critical boundaries that indicate stable and unstable regions instead of the one boundary predicted in existing analyses.

Improved countercurrent hydroprocessing method

Abstract: A process for upgrading a liquid petroleum or chemical stream wherein said feedstream flows countercurrent to the flow of a treat gas, such as a hydrogen-containing gas, in at least one reaction zone. The feedstream treated so that it is substantially free of particulate matter and foulant precursors.

Alternate double-frequency countercurrent ultrasonic-assisted simultaneous extraction method for seaweed protein and polysaccharide mixed product

Abstract: The invention provides an alternate double-frequency countercurrent ultrasonic-assisted simultaneous extraction method for a seaweed protein and polysaccharide mixed product and relates to the field of development and utilization of marine products. The alternate double-frequency countercurrent ultrasonic-assisted simultaneous extraction method comprises the following steps of: crushing dried seaweed into 40 meshes, and adding running water which is 10 to 20 times that of the weight of the seaweed powder into the seaweed powder for dissolving; regulating the temperature to be 60 to 100 DEG C, and regulating the pH value to be 8.0 to 10.0; extracting under the reference conditions of ultrasonic power of 200W in volume per liter by employing an alternate double-frequency countercurrent ultrasonic-assisted water extraction method, performing double-frequency alternate operation at the specific parameters of 15kHz and 20kHz, wherein the ultrasonic alternate working time is 1 to 5 seconds, and the extraction time is 30 to 80 minutes, and the feed liquid passes through an ultrasonic probe in a countercurrent cycle mode; and centrifugally extracting the supernatant, concentrating the supernatant, spraying and drying to obtain the product when the extraction is ended. Compared with the conventional extraction method, the alternate double-frequency countercurrent ultrasonic-assisted simultaneous extraction method provided by the invention is high in exaction efficiency; and compared with a single-frequency ultrasonic-assisted extraction method, the alternate double-frequency countercurrent ultrasonic-assisted simultaneous extraction method provided by the invention has the advantages of good wall-breaking and mass transfer effects and high energy utilization rate.

Estimation of the Maximum Efficiency of a Heat Recovery Burner

Abstract: Estimates are obtained for the maximum efficiency of a system consisting of a heat recovery burner connected to an ideal Carnot heat engine. The burner serves as a heater of the ideal heat engine, and the cold side is at the ambient temperature. Combustion products heat the hot wall of the ideal engine and then transfer heat to the combustible mixture supplied to the combustion chamber. Recovery of the heat of the combustible mixture occurs through the heat-conducting wall of a countercurrent heat exchanger, in which the combustion products and the combustible mixture move toward each other in the channels connected by a heat-conducting partition. An estimate is obtained for the total efficiency of the system, which is defined as the ratio of the net power of the ideal engine to the chemical energy flux reaching the burner device. It is shown that the total efficiency of the system can approach the Carnot-cycle efficiency with the maximum possible temperature of the hot side of the ideal heat engine.

A Novel Cross-Flow Cascade Packed Column Design and Simulation

Abstract: This paper develops a novel cross-flow cascade packed column. The column has a smaller width of packing in the direction of the gas flow and a bigger area for gas flow compared with a conventional cross-flow device with identical column diameter, stage height, and cross-sectional area for the irrigating liquid flows. The performance comparisons of the novel cross-flow cascade packed column with a countercurrent packed column for stripping ethanol from water indicate that the gas-phase pressure drop per theoretical stage in the novel cross-flow column is significantly lower than that in a countercurrent packed column operation under identical conditions. A methodology is developed for modeling the novel nine-stage cross-flow cascade packed column by using the number of transfer unit technique. This method is demonstrated by experimental data on ethanol-water.