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.

Holdup, flooding, and pressure drop in packed columns during countercurrent flow of mercury and water

Abstract: The hydrodynamics of countercurrent flow of liquids with a high density difference cannot be predicted reliably from correlations developed with data on fluids having low densities (usually water and organic solvents). Dispersed-phase holdup, flooding rates, and pressure drop during countercurrent flow of mercury and water were studied with several packing materials. Results show that, for a given packing, flooding rates and holdup can be correlated in terms of a single parameter, the superficial slip velocity. For the mercury-water system, this parameter is shown to be proportional to the packing diameter and packing void fraction for Raschig rings and solid cylindrical packing.

Single-layer flat-pipe full-isolation sewage pipe shell heat exchange device

Abstract: The utility model discloses a single-layer flat-pipe full-isolation sewage pipe shell heat exchange device which relates to a sewage heat exchange apparatus, in particular to an apparatus for directly conducting heat exchange to unfiltered sewage. The utility model aims at solving the problem that an existing passageway type sewage heat exchange device cannot realize full countercurrent heat exchange. Various flow layers are crossed and communicated. Inner cavities on heat exchange pipes of various layers are crossed and communicated. A sewage inlet is communicated with a heat exchange pipe adjacent to a shell. A medium shell pass cavity is formed between the inner wall of the shell and the outer wall of the adjacent heat exchange pipe. A medium water inlet is communicated with the medium shell pass cavity. The heat exchange pipes are flat pipes. Two passageway isolating plates are vertically arranged on an end pipe plate between each two heat exchange pipes. The upper and the lower ends of each isolating plate are respectively connected with an adjacent transverse clapboard. The end parts of two passageway isolating plates which are positioned at the sewage inlet and the sewage outlet are both provided with arc-shaped swirling plates. The heat exchange device effectively prevents the accumulation of contaminants, causes the contaminants to easily pass through the inner cavities of the heat exchange pipes and causes the direct sewage heat exchange to be conducted to the unfiltered water.

Dehydration of pumpkin using salt as osmotic agent: evaluation of water and salt coefficients of diffusion

Abstract: The objective of this work is to obtain experimental data on kinetics of osmotic dehydration of pumpkin and modeling such dehydration kinetics evaluating the effective diffusion coefficients corresponding to both salt and water at countercurrent mass transfer fluxes. Dehydration process was performed using sodium chloride as osmotic agent. Pumpkin cylinders (diameter: 1.5 cm) with ratio length/diameter of 5/3 were used in the dehydration experiments. Different experimental conditions were tested, varying the concentration of the osmotic solution (5-25 % w/w) and temperature (10-40 oC). Effective coefficients of diffusion for salt and water were obtained using only the first term of the analytical solution of Fick’s Law for infinite cylinders (for short and long periods). Both salt and water diffusivities increased with temperature, and no dependence on osmotic solution concentration was observed.

Waste heat recovery system

Abstract: The invention provides a waste heat recovery system. The waste heat recovery system comprises a high-temperature water tank, a low-temperature water tank and a working medium, and further comprises a first heat exchanger, a second heat exchanger, a third heat exchanger and a working medium pump which are connected in the flowing direction of the working medium in sequence, wherein the second heat exchanger is installed in the high-temperature water tank, and the third heat exchanger is installed in the low-temperature water tank. According to the waste heat recovery system, hot water is produced firstly, and the waste heat produced after the hot water is produced is used for producing low-temperature water. The utilization rate of waste heat is improved, and differentiated demands for different water temperatures of users are met. The first heat exchanger comprises a shell, a heat exchanging pipe and baffle plates arranged inside the shell, wherein the heat exchanging pipe penetrates through the shell and the baffle plates. The flowing direction of fluid outside the heat exchanging pipe is changed through the baffle plates, the turbulence of the fluid outside the pipe is enhanced, and the heat exchanging effect is improved. Countercurrent flow heat exchanging is formed, and the heat exchanging effect is further improved.

Method and apparatus for compressing a natural gas stream

Abstract: A method and apparatus for compressing a natural gas stream is disclosed. The natural gas stream to be compressed is liquefied and then compressed by means of at least one cryogenic pump. Liquefaction of the natural gas stream to be compressed preferably takes place using the energy from a low-temperature process, specifically in the exchange of heat countercurrent to at least one medium to be heated, preferably countercurrent to a cryogenic medium.