Showing papers on "Countercurrent exchange published in 2013"

Continuous Countercurrent Tangential Chromatography for Monoclonal Antibody Purification

Abstract: Recent increases in antibody titers have generated renewed interest in lower-cost continuous chromatographic processes for antibody purification. The objective of this study was to design, build, and test a continuous countercurrent tangential chromatography system in which the resin (in the form of a slurry) flows sequentially through a series of static mixers and hollow fiber membrane modules to accomplish the binding, washing, elution, stripping, and equilibration steps in continuous operation with true countercurrent staging. Experimental studies were performed for the purification of an IgG4 monoclonal antibody from a model feed containing bovine serum albumin and myoglobin using a protein A affinity resin. Batch uptake / desorption experiments were used in combination with critical flux filtration data to design the continuous countercurrent tangential chromatography system. The process was stable during continuous operation, providing the IgG4 at 94% yield with greater than 97% purity. The antibody...

Co2 capture processes using rotary wheel configurations

Abstract: The disclosure relates to a continuous or semi-continuous, cyclic, countercurrent sorption-desorption method for enhanced control, separation, and/or purification of CO2 gas from one or more sources of a mixture of gases through integrated use of solid monolithic sorbents having a sorption selectivity for the CO2 gas, wherein liquid phase water is added to increase the heat capacity of the mixed gas source(s) in order to achieve a thermal wave moving through the thickness of the sorbent material faster than the CO2 sorption wave.

Relation between oil–water flow and extraction performance in liquid–liquid countercurrent centrifugal extractors with Taylor vortices

Abstract: A countercurrent centrifugal extractor with an inner rotor and a stationary outer wall has been developed in which aqueous and organic phases flow countercurrently between two walls. The formation of stable Taylor vortices in the gap makes multistage extraction possible. Understanding the relation between flow state and percent extraction is important for achieving a greater number of theoretical stages in a single extractor. Hence, oil–water countercurrent flow is measured by ultrasonic velocity profiling, without disturbing the flow, under different feed rates of solutions and rotating speeds of the inner rotor. In continuous extraction tests, Zn2+ in nitric acid and di-(2-ethylhexyl)-phosphoric acid diluted by n-dodecane are used. Measurement results are verified by numerical simulation. Finally, a correlation chart of flow patterns and operating conditions is prepared.

High-performance extraction operation using emulsion flow protected by surfactants in a liquid-liquid countercurrent centrifugal extractor

Abstract: A small-size countercurrent centrifugal extractor with Taylor vortices in a narrow fluid region between an inner rotor and a stationary outer wall has been developed for high-performance liquid–liquid extraction. The extractor enables fast multistage extraction, and control of the emulsion flow is important for achieving superior extraction performance. To achieve a higher number of theoretical stages, rotation speed is initially increased to 1500 rpm to form an emulsion flow and subsequently decreased to the required level. The addition of (1) two types of surface-activating agents (sodium di(2-ethylhexyl) sulfosuccinate and sodium dodecyl sulfate) and (2) polymer protective agents (polyethylene glycol) was tested for maintaining a stable emulsion flow without sacrificing effective oil–water contact at lower rotation speeds. It was found that addition of a small amount of such agents allows for multistage extraction with a higher number of theoretical stages.

Multi-staging for extraction of cesium from nitric acid by a single liquid–liquid countercurrent centrifugal extractor with Taylor vortices

Abstract: Fission products that emit considerable decay heat and radioactivity, such as 137Cs, have a large impact on waste management. Small and high-performance extractor is desirable for separating such nuclei. In this study, we implemented the continuous extraction of Cs from nitric acid in a single liquid–liquid countercurrent centrifugal extractor with Taylor Vortices by calix[4]arene-bis(t-octylbenzo-crown-6)(BOBCalixC6) as an extractant with trioctylamine(TOA) as a suppressant and with 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) as a phase modifier. Because of slow extraction kinetics of this process, extraction with multiple theoretical stages by just replacing conventional extractors into the single centrifugal extractor is difficult. Hence, we improved the dispersion of organic phase by an inner rotor made of lipophilic epoxy resin and elevating the solution temperature to lower the viscosity. Higher temperature was not appropriate from the aspect of chemical equilibrium in ...

MathModelica in Modeling of Countercurrent Heat Exchangers

Abstract: The countercurrent heat exchangers can be modeled using analogies from electrical circuits composed of resistors R and capacitators C. Electrical RC analog of the heat exchangers is built and tested. Program MathModelica Lite (MML) in environment OpenModelica (OM) have been used. These are free for academic use.

Analytical Study on Thermal and Mechanical Design of Printed Circuit Heat Exchanger

Abstract: The analytical methodologies for the thermal design, mechanical design and cost estimation of printed circuit heat exchanger are presented in this study. In this study, three flow arrangements of parallel flow, countercurrent flow and crossflow are taken into account. For each flow arrangement, the analytical solution of temperature profile of heat exchanger is introduced. The size and cost of printed circuit heat exchangers for advanced small modular reactors, which employ various coolants such as sodium, molten salts, helium, and water, are also presented.

Comparison of Two Different Heat-Integrated Exhaust Purification Devices for Monovalent CNG Engines

Abstract: In this paper, two different heat-integrated reactor concepts for the exhaust aftertreatment of natural gas powered vehicles are presented. While one concept is based on previously published fully integrated systems, in the second one, an efficient metallic countercurrent heat exchanger is closely combined with a separate, catalytically coated ceramic honeycomb. For rapid cold start and for backpressure-reduced operation under high load conditions, both devices are equipped with an electric heater and a bypass system. The characteristic differences between both approaches will be demonstrated by drive cycle simulations.

Liquid–liquid flow in an impeller–stator spinning disc reactor

Abstract: Liquid–liquid flow patterns in an impeller–stator spinning disc reactor are qualitatively described. The liquid–liquid flow is studied by contacting water and n-heptane at rotational speeds up to 900 RPM, an axial disc spacing of 1.0 × 10 −3 m, and aqueous volume fractions between 0 and 1 m AQ 3 m L − 3 . The liquid–liquid flow is characterized by six different flow regimes. Each regime is characterized by its continuous liquid phase and the degree of dispersion of the dispersed liquid phase. Regime transitions depend on the formation of boundary layers on the impeller and the stator, the shear stress intensity and the aqueous volume fraction. The impeller is able to selectively pump n-heptane through the reactor, whilst it is intensively mixed with water that remains in the reactor. Combining mixing and separation in one compact reactor is an important step toward a countercurrent operated impeller-based centrifugal extractor.

Analyzing and modeling the dynamic thermal behaviors of direct contact condensers packed with PCM spheres

Abstract: Condensers serve as important components for humidification–dehumidification (HDH) desalination plants. Based on the interpenetration continua approach with volume averaging technique, a mathematical dynamic model for analyzing the heat and mass transfer within direct contact condensers with co-current or countercurrent flow arrangement was developed. It was validated against the experimental data from a small scale HDH desalination system. Comparisons including the productivities and the temperature profiles of gas, liquid, and solid phases show good agreement with the measurements. Phase change material (PCM) melting processes have little effect on water production rate for co-current flow arrangement, but the condenser packed with PCM capsules have higher water production rates than that packed with air capsules packed under given conditions. The relative humidity profile of the bulk gas shows contrary trend with the gas temperature profile. The direct contact condenser with countercurrent flow arrangement can provide much better heat and mass transfer between gas and water and produce about 16.3% more fresh water than the same condenser with co-current flow arrangement in 4 h under given conditions.

On the Construction of an Experimentally Based Set of Equations to Describe Cocurrent and Countercurrent, Two-Phase Flow of Immiscible Fluids Through Porous Media

Abstract: Generalized flow equations developed for two-phase flow through porous media contain a second term that enables proper account to be taken of capillary coupling between the two flowing phases. In this study, a partition concept, together with a novel capillary pressure equation for countercurrent flow, have been introduced into Kalaydjian’s generalized flow equations to construct modified flow equations which enable a better understanding of the role of capillary coupling in horizontal, two-phase flow. With the help of these equations it is demonstrated that the reduced flux observed in countercurrent flow, as compared to cocurrent flow, can be explained by the reduction in the driving force per unit volume which comes about because of capillary coupling. Also, it is shown experimentally that, because fluids flow through a void space reduced in magnitude due to the presence of immobile irreducible and residual saturations, the capillary coupling parameter should be defined in terms of a reduced porosity, rather than in terms of porosity. Moreover, it is shown statistically that the countercurrent relative permeability curve is proportional to the cocurrent relative permeability curve, the constant of proportionality being the capillary coupling parameter. Finally it is suggested that one can eliminate the need to determine experimentally countercurrent relative permeability curves by making use of an equation constructed for predicting the magnitude of the capillary coupling parameter.

Countercurrent detection method, anti-countercurrent control method and device and anti-countercurrent system

Abstract: The invention particularly relates to a countercurrent detection method, an anti-countercurrent control device and an anti-countercurrent system. Whether a countercurrent happens or not is detected by calculating of time difference between a voltage zero crossing point and a current zero crossing point of a power grid access point, detection speed is high, the countercurrent can be detected in 1-5 periods, so that adjustment speed is accelerated, the occurrence that a power grid device is protected through outage, time is won for flexible adjustment, and the probability of forced outrage on a grid power source is reduced.

Mathematical Modeling and Simulation of Drying Using Two Industrial Concurrent and Countercurrent Rotary Dryers for Ammonium Nitrate

Abstract: Drying of ammonium nitrate (AN) is accomplished in the Shiraz Petrochemical Complex (SPC) using a concurrent rotary dryer following a countercurrent rotary dryer. A mathematical model for these rotary dryers including heat and mass transfer was developed. The model was checked against industrial-scale data, which showed a good agreement. The average absolute deviation of the simulation results compared to the industrial data for the concurrent dryer was 4.0% for solids moisture, 1.3% for solids temperature, and 1.8% for air temperature and for the countercurrent dryer it was 9.0% for the solids moisture, 2.0% for solids temperature, and 4.6% for air temperature. These simulation results reveal that for outlet solid moisture, inlet AN moisture, and air temperature as well as the outlet temperature of product, the inlet solid and air temperature have major effects for both concurrent and countercurrent flow.

Countercurrent enhances acceleration sensation in galvanic vestibular stimulation

Abstract: This study reports that the effect of galvanic vestibular stimulation (GVS) can be enhanced by giving a countercurrent before the normal current stimulation in the forward direction In order to investigate the effect of the countercurrent on GVS, we applied various kinds of amplitudes and durations of the countercurrent before the normal stimulation The strength of the effect was measured by the subjective response and body sway As a result, the enhancing effect by the countercurrent does not only appear in the objective response but also in the subjective reports and we found that the effect of the countercurrent was enhanced in response to the amount of charges of the countercurrent before normal stimulations Our result implies that there is a capacitor on the current path that enhances the GVS effect by the countercurrent

Performance improvement of countercurrent-flow direct contact membrane distillation in seawater desalination systems

Abstract: The modeling equations for the temperature distribution and pure water productivity in a parallel-plate direct contact membrane distillation module under countercurrent-flow were derived theoretically with the use of the mass balance on each subchannel. The analytical solution is obtained by using the separated variables method with an orthogonal expansion technique extended in power series. The pure water productivity, average Nusselt number, and temperature distributions of both hot and cold feed streams are represented graphically with the feed velocity and the inlet saline temperature as parameters. The improvements of device performance were achieved under the countercurrent-flow operation. The influences of operation and design parameters on the pure water productivity are also discussed.

An Experimental Investigation of the Reynolds Analogy and its Modifications Applied to Annular Condensation Laminar Flow of R134a in a Vertical Tube

Abstract: The Reynolds analogy and its modifications are applied to forced convection laminar in-tube condensation to predict the heat transfer coefficient of R134a by means of well-known two-phase friction factors and agreed void fraction models and correlations explained in the authors’ previous works. The vertical test section is a 0.5 m long countercurrent flow double tube heat exchanger with refrigerant flowing in the inner smooth copper tube (8.1 mm i.d.) and cooling water flowing in the annulus (26 mm i.d.). The test runs are performed at average saturated condensing temperatures of 40 °C (Pr = 0.92) and 50 °C (Pr = 0.97). The heat fluxes are between 10.16 and 66.61 kW m−2 while the mass fluxes are between 260 and 515 kg m−2 s−1 for the vertical test sections. The Reynolds’ model is modified by various two-phase flow models and correlations to account for the partial condensation inside the tube. The refrigerant side heat transfer coefficients are determined within ±30% using the two-phase friction factors of Wallis, Moeck, Fore et al., while all the proposed friction factor correlations for the Reynolds analogy, Prandtl and Taylor analogy, and Colburn analogy predict the experimental friction factor within a ±20% deviation band. The importance of altering the Prandtl number to the Reynolds analogy (Pr = 1) is also shown in the paper.

Solution desiccant air handling device circularly driven by multiple stages of heat pumps

Abstract: The invention relates to a solution desiccant air handling device circularly driven by multiple stages of heat pumps. The solution desiccant air handling device comprises a countercurrent packing tower dehumidifier, a countercurrent packing tower regenerator, two solution pumps, a solution heat exchanger and more than two stages of heat pump circulating systems, wherein the heat pump circulating systems are arranged between the dehumidifier and the regenerator; each heat pump circulating system comprises a throttle valve, a compressor, a condenser and an evaporator which are connected in sequence through refrigerant pipes; the casings of the condensers are connected in series in sequence; the casings of the evaporators are connected in series in sequence; and solution at the bottom of the dehumidifier is connected with one solution pump, one heat exchange pipe of the solution heat exchanger and the serially connected condensers in sequence through pipes to reach the inlet at the upper part of the regenerator, performs heat transfer and mass transfer with regenerated air in the regenerator, then reaches the outlet at the bottom of the regenerator to be connected with the other solution pump, the other heat exchange pipe of the solution heat exchanger and the serially connected evaporators in sequence through pipes to return to the inlet at the upper part of the dehumidifier, performs heat transfer and mass transfer with treated air in the dehumidifier and then returns to the outlet at the bottom of the dehumidifier.