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.

Multi-stage countercurrent process for extracting protein from Antarctic Krill (Euphausia superba).

Abstract: To systematically study multi-stage countercurrent process for Antarctic krill protein extracting and to optimize the multi-stage countercurrent technology, the solubility of Antarctic krill proteins after multi-step dissolution was explored firstly; multi-step extraction was investigated; and then multi-stage countercurrent system for protein extraction was carried out In single step extraction, krill-to-water ratio and pH were chosen as 1:10 and 125 respectively, in order to extract more protein In the multi-step dissolution process, the protein solubility of aqueous solution at pH 125 was 330 ± 08 mg/mL Multi-step cross-flow processing testified the feasibility of multi-stage countercurrent assumption Three-stage countercurrent method using krill-to-water ratio 1:10 extracted, 951 ± 06% protein from krill, where almost the same water as previous works The total recovery yield of 679 ± 16% was achieved after precipitation at pH 45

Hydrotreating process for light hydrocarbons

Abstract: The invention discloses a lightweight hydrocarbon hydrogenising method, which adopts a first stage countercurrent hydrogenising reactor and a conventional co-current hydrogenising reactor connected in series. The raw material enters into a flash evaporation area of the countercurrent hydrogenising reactor at a lower temperature, gas-phase hydrocarbon flows upwards and performs a reaction of diene and mercaptan producing sulfide and a diene hydrogenising reaction at the upper part of the countercurrent hydrogenising reactor, high boiling sulfide generated by the upper part reaction and liquid-phase hydrocarbon after the raw material flash evaporation flow downwards together, and an alkylation reaction of thiophene sulfur and olefin is generated; Hydrogen enters at the bottom of the countercurrent hydrogenising reactor and flows upwards. Liquid phase discharged at the bottom of the countercurrent hydrogenising reactor and new hydrogen are mixed and enter into the co-current hydrogenising reactor to perform the reactions, such as deep hydrodesulfurization, selective cracking or isomerization and the like after being heated. The method has the advantages that the technological process is simple, the desulphurization effect is good, the octane value loss is low, the product yield is high, and the required equipment is few. The method is mainly used for the secondary processing the poor-quality gasoline, namely, the upgrading process of catalytic cracking gasoline, coking gasoline or thermal cracking gasoline.

Conditions for Equivalency of Countercurrent Vessel Heat Transfer Formulations

Abstract: Previous models of countercurrent blood vessel heat transfer have used one of two, different, equally valid but previously unreconciled formulations, based either on: (1) the difference between the arterial and venous vessels' average wall temperatures, or (2) the difference between those vessels' blood bulk fluid temperatures. This paper shows that these two formulations are only equivalent when the four, previously undefined, "convective heat transfer coefficients" that are used in the bulk temperature difference formulation (two coefficients each for the artery and vein) have very specific, problem-dependent relationships to the standard convective heat transfer coefficients. (The average wall temperature formulation uses those standard coefficients correctly.) The correct values of these bulk temperature difference formulation "convective heat transfer coefficients" are shown to be either: (1) specific functions of (a) the tissue conduction resistances, (b) the standard convective heat transfer coefficients, and (c) the independently specified bulk arterial, bulk venous and tissue temperatures, or (2) arbitrary, user defined values. Thus, they are generally not equivalent to the standard convective heat transfer coefficients that are regularly used, and must change values depending on the blood and tissue temperatures. This dependence can significantly limit the convenience and usefulness of the bulk temperature difference formulations.

An Analytical Study of Critical Heat Flux of a Two-Phase Thermosyphon.

Abstract: An analytical study has been made of critical heat flux of a two-phase thermosyphon, in which a liquid film and a vapor flow in a manner of countercurrent annular flow. An equation governing the flow of the liquid film and other equations for mass and energy balance in the thermosyphon are solved together under two conditions ; first, the critical heat flux takes place when liquid supply to the thermosyphon is just equal to the evaporation of the liquid due to the heat input into it, and second, thickness of the liquid flow is determined such that interface of the annular flow is kept stable. Thereby, two correlations are derived for both limiting conditions of 2/(C2ik2Nk) and then one of them for 2/(C2ik2Nk)»1 is in good agreement with the existing CHF data in a closed two-phase thermosyphon as well as a generalized correlation derived from dimensional analysis.