Extraction Coil Research Articles

Performance evaluation of serpentine tube coupled with modified twisted tapes utilized as heat extraction coil in solar ponds

The thermal energy collected and stored by solar ponds is usually extracted by using some heat exchangers, where curved tubes form their core. The present study aims to appraise the performance of a serpentine tube under varied mass flow rates and inlet temperatures of the working fluid. Three different types of twisted tapes nominated as uniform twist pitches (U), low to high twist pitches (LH), and high to low twist pitches (HL) are employed to enhance the heat extraction rate. This article is the first report addressing the application of non-uniform twisted tapes as turbulators in a serpentine tube. In this regard, a solar pond simulator containing salt water is designed and fabricated. Numerical simulations are also carried out to display the transport phenomena inside the models. The numerical results are compared with the experimental data, and a close agreement is found. From the thermal point of view, the sequence of twisted tapes is LH > HL > U, while it follows the order of U > LH > HL according to the frictional loss. The findings demonstrate that depending on operating conditions, the heat extracted by the modified cases is 4 to 70% more than the base model. It is also found that employing non-uniform twisted tapes results in lower flow resistance compared to the uniform case. The pressure drop augmentations produced by U, LH, and HL TTs are 26.5%, 17.5%, and 10.4%. Further, the overall performance index is higher than unity for all the enhanced cases. The best case is the twisted tape having low to high twist pitches (LH) which has an average performance index from 2.03 to 2.71.

Lab-On-A-Chip Extraction of Phenolic Compounds from Extra Virgin Olive Oil

A novel liquid–liquid extraction method of phenolic compounds from extra virgin olive using microfluidic technique was developed. The microdevice of polydimethylsiloxane (PDMS) was designed in two parts; the first one to carry out the extraction of polyphenols using only an alkaline aqueous solution and the second one to develop the reaction product using Folin–Ciocalteu reagent, which was measured at 730 nm at the microchip exit. Hydrodynamic and chemical parameters, such as flowrates of extraction and reaction, length of microchannels, extraction pH, extraction buffer concentration, and concentration of Folin–Ciocalteu reagent, were evaluated. Although all parameters were important, the results showed that pH, carbonate buffer concentration, and the Folin–Ciocalteu reagent concentration were significant factors and that the increase in the length of the extraction coil enhanced the extraction percentage. The results showed higher extraction efficiency by the microfluidic method, between 46 and 67%, than for the other two batch extraction methods.

Micro-Solvent Extraction with Sequential Injection Lab-at-Valve for Successive Determination of Cationic and Nonionic Surfactants

A successive determination of cationic and nonionic surfactants using sequential injection lab-at-valve (SI-LAV) micro solvent extraction has been developed. The method is based on ion association formation between cationic and/or K-nonionic surfactant with tetrabromophenolphthalein ethyl ester (TBPE•H). The blue associate is extracted quickly into 1,2-dichloroethane (DCE) in an extraction coil which is set in a SI-LAV manifold. The segments are dispensed to a pipette tip (like a miniature separation funnel) fitted onto a port of a multi-position valve. This leads to the separation of the aqueous and organic phases. Absorbance of the DCE phase (the bottom part in the pipette tip) can be measured at 610 nm via optic fibers. Without the addition of KCl, absorbance of cationic surfactant can be obtained, while with adding KCl, absorbance of nonionic surfactants can be obtained. The proposed method provides an automated, novel, simple and economical strategy for simultaneous determination of cationic and nonionic surfactants without a membrane separator.

Sequential injection analysis with lab-at-valve (SI-LAV) for the determination of solasodine in Solanum species

The development of sequential injection analysis with lab-at-valve (LAV) semi-automated system on-line liquid-liquid extraction is demonstrated for spectrophotometric determination of solasodine in various Solanum species fruits. The main proposed is semi-automated extractive determination of solasodine using methyl orange as colorimetric reagent. After optimization of the system, sample, reagent and organic solvent were sequentially aspirated into an extraction coil connected to the center of a selection valve, where extraction took place by flow reversal. The aqueous and organic phases were separated in a lab-at-valve unit attracted to one of the ports of the selection valve. The absorption of ion-pair solasodine-methyl orange complex in the organic phase was measured spectrophotometrically at 420 nm. The method performances, including reproducibility, linearity, sensitivity and accuracy, were also evaluated. The proposed method is simple, reproducible and accurate. It was successfully applied to the determination of solasodine in Solanum aculeatissimum Jacq., Solanum violaceum Ortega., Solanum melongena Linn. and Solanum indicum Linn. fruits in Solanaceae family. Results obtained were in good agreement with those obtained by batch wise spectrophotometric method. It is also suitable and useful for determination of solasodine in other medicinal plants.

Continuous-Flow System for Separation of Lead(II) from Zinc(II) by Forward- and Back-Extraction Processes

A continuous-flow system for the separation of lead(II) (Pb II ) from zinc(II) (Zn II ) was developed. The system consists of two extraction coils—one for forward-extraction and the other for back-extraction—connected in series through a phase separator. Firstly, in the forward-extraction process, most Pb II and a small amount of Zn II are extracted into chloroform phase with dithizone (H2dz). Subsequently, in the back-extraction process, Pb II is back-extracted into the aqueous phase with nitric acid while the Zn II is retained in the organic phase. The experimental conditions were optimized based on the kinetic constants of Zn II and Pb II in forward- and back-extraction. The optimal flow system can quantitatively separate Pb II from Zn II by a single injection of a sample solution. This method is also applicable to a sample solution containing a much higher concentration of Zn II (4.89 × 10 –3 mol dm –3 ) than that of Pb II (5.14 × 10 –6 mol dm –3 ).

Recent Developments in Flow Injection/Sequential Injection Liquid-Liquid Extraction for Atomic Spectrometric Determination of Metals and Metalloids

This review aims to provide a critical overview of automated flow injection and sequential injection liquid-liquid extraction for preconcentration and/or separation of ultra-trace metal and metalloid species hyphenated with atomic spectrometric detection systems, including some new trends and applications in the subbranches of cloud point extraction (CPE), wetting film extraction (WFE), supported liquid membrane extraction (SLME), extraction chromatography (EChr), and liquid-phase microextraction (LPME) techniques. The analytical performance of flow-injection/sequential injection liquid-liquid extraction methods is markedly affected by the components of the flow network such as segmentor, extraction coil, and phase separator. Thus, an overall presentation of system components along with some novel strategies for interface with atomic spectrometers is discussed and exemplified with selected applications.

Spectrophotometric Determination of Anionic Surfactant Based on Ion-pair Formation with Methylene Blue in Reversed Flow Injection Mode

A simple reversed flow injection system with minimal consumption of organic solvent has been developed for the spectrophotometric determination of anionic surfactant (AS) in water samples. The method is based on the ion-pair formation between anionic surfactant and Methylene Blue (MB) and its extraction to chloroform. Sodium dodecyl sulfate (SDS) is used as a model anionic surfactant. The sample and MB solutions are each delivered by two peristaltic pumps and merged to form the ion-pair of AS and MB. Small amounts of chloroform (50 mm 3 ) are injected every 15 s to the merged solution. The ion-pair is extracted to the chloroform phase while the solution is passing through an extraction coil. The absorbance of both phases (aqueous and organic phases) is measured sequentially at 652 nm without phase separation. Analytical parameters such as extraction coil length and MB concentration have been optimized. The dynamic ranges of calibration curves (0.1 ~ 1 and 2 ~ 8 μmol dm -3 ) are selected depending on the analyte concentration by changing MB concentration. Calibration curves are linear (r 2 > 0.997) over the ranges; LOD (3.3 σ) is 0.054 μmol dm -3 . Relative standard deviations of repeated measurements are 2.44% (n = 8, CSDS = 1 μmol dm -3 ) and 1.46% (n = 7, CSDS = 8 μmol dm -3 ). The throughput rate of the measurement is 4 samples per minutes. The proposed method can be applied to the determination of anionic surfactant in river, pond and house sewage water samples.

Flow injection wetting-film extraction system for flame atomic absorption spectrometric determination of cadmium in environmental waters

A newly simple flow injection wetting-film extraction system coupled to flame atomic absorption spectrometry (FAAS) has been developed for trace amount of cadmium determination. The sample was mixed on-line with sodium diethyl dithiocarbamate and the produced non-charged Cd(II)–diethyl dithiocarbamate (DDTC) chelate complex was extracted on the thin film of diisobutyl ketone (DIBK) on the inner wall of the PTFE extraction coil. The wetting-film with the extracted analyte was then eluted by a segment of the cover solvent, and transported directly to the FAAS for evaluation. All the important chemical and flow parameters were optimized. Under the optimized conditions an enhancement factor of 35, a sample frequency of 22 h −1 and a detection limit of c L = 0.7 μg l −1 Cd(II) were obtained for 60 s preconcentration time. The calibration curve was linear over the concentration range 1.5–45.0 μg l −1 Cd(II) and the relative standard deviation, R.S.D. ( n = 10) was 3.9%, at 10.0 μg l −1 concentration level. The developed method was successfully applied to cadmium determination in a variety of environmental water samples as well as waste-water sample.

Automatic sequential injection liquid–liquid micro-extraction system for on-line flame atomic absorption spectrometric determination of trace metal in water samples

An automatic sequential injection (SI) liquid–liquid micro-extraction system incorporating a dual-conical micro-gravitational phase separator is proposed as versatile approach for on-line metal preconcentration and/or separation. Coupled to flame atomic absorption spectrometry (FAAS) the potentials of this novel schema are demonstrated for lead determination in water samples at the μg l −1 level. The non-charged lead complex with ammonium pyrrolidine dithiocarbamate (APDC) was extracted on-line into 300 μl isobutyl methyl ketone (IBMK) through the extraction coil. The organic phase containing the extracted metal complex is collected in the upper cavity of the phase separator and then forwarded to the nebulizer. All the critical parameters were optimized and offered good performance characteristics and high preconcentration ratios. A sample consumption of 10.5 ml enabled the determination of Pb(II) in the range of 3.0–250.0 μg l −1 with an enhancement factor of 120 and a sampling frequency of 25 h −1. The detection limit and the precision were 1.4 μg l −1 and 2.9% (at 50.0 μg l −1 concentration level), respectively. The proposed method was evaluated by analyzing certified reference material and was applied successfully to the analysis of natural water samples.

Production of a Positron Microprobe Using a Transmission Remoderator

A production method for a positron microprobe using a beta+-decay radioisotope (22Na) source has been investigated. When a magnetically guided positron beam was extracted from the magnetic field, the combination of an extraction coil and a magnetic lens enabled us to focus the positron beam by a factor of 10 and to achieve a high transport efficiency (71%). A 150-nm-thick Ni(100) thin film was mounted at the focal point of the magnetic lens and was used as a remoderator for brightness enhancement in a transmission geometry. The remoderated positrons were accelerated by an electrostatic lens and focused on the target by an objective magnetic lens. As a result, a 4-mm-diameter positron beam could be transformed into a microprobe of 60 microm or less with 4.2% total efficiency. The S parameter profile obtained by a single-line scan of a test specimen coincided well with the defect distribution. This technique for a positron microprobe is available to an accelerator-based high-intensity positron source and allows 3-dimensional vacancy-type defect analysis and a positron source for a transmission positron microscope.

ET-AAS determination of aluminium in dialysis concentrates after continuous flow solvent extraction

Conditions of a continuous flow extraction (CFE) of aluminium acetylacetonate in acetylacetone and aluminium 8-hydroxyquinolinate into methylisobutylketone (lengths of reaction and extraction coils, flow rates of aqueous and organic phases and their flow rate ratio, pH of aqueous phase, lengths of coils for transport of aqueous and organic phases and effect of salts) were studied. The analytical signal of the aluminium chelates present in the organic phase was measured at 309.3 nm using atomic absorption spectrometry with electrothermal atomization (ET-AAS) at the flow rate ratio F aq/ F org = 3 for aqueous and organic phases. The five points calibration curves were linear ( R 2 0.9973 and 0.9987) up to 21 μg l −1 Al with the limits of detection of 0.3 μg l −1 and the recovery 100 ± 2% and precision of 3% at 2–10-fold dilution of the dialysis concentrates. The acetylacetonate method was applied to the determination of aluminium in real dialysis concentrates. Aluminium in concentrations 5–6 μg l −1 (R.S.D.s 5–10% in real samples) were found and the results were in the very good agreement with those obtained by an ET-AAS using preconcentration of Al(III) on a Spheron-Salicyl chelating sorbent (absolute and relative differences were under 0.4 μg l −1 and 8.2%, respectively).

Development of Sequential Injection-Lab-at-Valve (SI-LAV) Micro-Extraction Instrumentation for the Spectrophotometric Determination of an Anionic Surfactant

The development of instrumentation for sequential injection analysis with a "lab-at-valve" (SIA-LAV) micro-extraction system is presented. The extractive determination of an anionic surfactant using methylene blue was selected as a model. Sample, reagents and organic solvent were sequentially aspirated into an extraction coil connected to the center of a selection valve, where extraction took place by flow reversal. The aqueous and organic phases were separated in a LAV unit attached to one port of the valve. The LAV unit situated a fiber-optic spectrophotometer to monitor the absorbance change of the extract product in the organic phase. The developed SIA-LAV system offers an alternative micro-total analysis system for automated micro-extraction.

Application of a Stepwise Flow Ratiometry without Phase Separation to the Determination of the Chloroform/Water Distribution Coefficients of Volatile Diazines

The chloroform/water distribution coefficients (K(D)) of sixteen diazine compounds were determined by a stepwise flow ratiometry. An aqueous solution of analyte was delivered and merged with chloroform. The flow rate ratio of both the phases was varied stepwise under a constant total (chloroform+aqueous) flow rate. The analyte was extracted to chloroform while both the phases, which were segmented by each other, were passing through an extraction coil. The segmented stream was then led to a UV/Vis detector directly without phase-separation. The absorbance of the chloroform and aqueous phases (A(o) and A(a), respectively) was each measured at the maximum absorption wavelength of the analyte. The plots of A(-1) against R(f), (AR(f))(-1) against R(f)(-1), and AR(f) against A gave straight lines, where A was A(o), A(a) or the sum of them (A(S)). The K(D) of the analyte was calculated from the slopes and intercepts of the plots. The log K(D) values obtained for the analytes (-0.5-1.4) were agreed well with the values measured by a shake-flask method. The present method is simple, rapid (5 min/determination) and applicable to the volatile compounds with reasonable precision (standard deviation of log K(D)<0.07).

Flow injection system with in-line Winkler?s procedure using 16-way valve and spectrofluorimetric determination of dissolved oxygen in environmental waters

Flow injection spectrofluorimetry with in-line Winklers procedure was developed for the dissolved oxygen (DO) determination. 2-Thionaphthol reacted with iodine produced by Winkler’s method to form fluorescence inactive disulfide compound. To automate the process completely, a 5-channel flow system with a newly designed 16-way valve was assembled. The system consisted of a dispersion coil (DC), a precipitate formation coil (PFC), a precipitate dissolving coil (PDC), and extraction coil (EC). A calibration can be constructed by using a standard iodine solution for dissolved oxygen. The calibration graph was linear over the range 1.2×10−4∼6.0×10−4 mol l−1 iodine (1.96∼9.80 mg O l−1)). The relative standard deviation (n=6) was below 0.3% for the 4×10−4 mol l−1 iodine (6.27 mg O l−1) determination. The sample throughput was 12/h.

INTEGRATED COMBINED H EAT AND P OWER AND G AS C OOLING

Fully dedicated on-site combined heat and power (CHP) systemspresent both challenges and opportunities for large multi-buildingprojects; particularly when employing a combined cycle approach in the3-20 MW range 1 . While some distributed power generation systemshedge their bets through reliance on both the sale and export of power(e.g., paralleling with a serving utility to achieve favorable economics),disappointing de-regulation benefits and the failure of energy trading tosmooth out power supply vs. demand cost uncertainty has been a sober-ing experience for many California customers.Recent rethinking by concerned CHP designers has focused onexploring smaller footprint alternatives to use of higher cost heat-recov-ery-steam-generators (HRSGs). One such approach involves the use ofprefabricated and fully integrated steam generators, complete with asso-ciated heat exchangers, controls and pumping systems, employing lowpressure, non-volatile, recirculating heat transfer fluids (HTF) capable ofdirect heat extraction of turbine exhaust gas waste heat to generate steamand allow cascading the remaining captured waste heat to drive absorp-tion chiller(s), and space and domestic hot water heating systems en-abling greater utilization of available heat reclamation potentials in sat-isfying highly variable annual building power, heating and cooling loaddemands. This is achieved through maintaining favorable log-mean-tem-perature-differentials (LMTDs) at the turbine gas extraction coil also re-sulting in a lower exhaust gas temperature discharge to ambient. Variousexamples of such alternative HRSG cycles will be presented for gas turbine driven chiller and/or generator application, as well as gas turbinecombined cycle operation to demonstrate the operational versatility andlife cycle benefits of this approach for the above referenced range ofcommercially available gas turbines.

Flow injection system with in-line Winkler’s procedure using 16-way valve and spectrofluorimetric determination of dissolved oxygen in environmental waters

Flow injection spectrofluorimetry with in-line Winklers procedure was developed for the dissolved oxygen (DO) determination. 2-Thionaphthol reacted with iodine produced by Winkler’s method to form fluorescence inactive disulfide compound. To automate the process completely, a 5-channel flow system with a newly designed 16-way valve was assembled. The system consisted of a dispersion coil (DC), a precipitate formation coil (PFC), a precipitate dissolving coil (PDC), and extraction coil (EC). A calibration can be constructed by using a standard iodine solution for dissolved oxygen. The calibration graph was linear over the range 1.2×10−4∼6.0×10−4moll−1 iodine (1.96∼9.80mgOl−1)). The relative standard deviation (n=6) was below 0.3% for the 4×10−4moll−1 iodine (6.27mgOl−1) determination. The sample throughput was 12/h.

Determination of distribution coefficients by stepwise flow ratiometry/spectrophotometric detection without phase separation

A new system of flow ratiometry having UV detection without a phase separator was developed and applied to the determination of the chloroform/water distribution coefficients (KD) of phenol and its derivatives. An aqueous solution of analyte and chloroform was delivered independently and merged at various flow ratios (Rf). The ratio was changed stepwise. Both phases, segmented each other, passed through an extraction coil and were directly led to a flow cell, where the absorbance of each phase was monitored. A wide-bore tubing (2 mm, i.d., 20 cm long) was inserted between the extraction coil and the flow cell in order to coalesce the chloroform segments and/or aqueous segments. Thus formed bigger segments were easily measured. The KD was calculated from the slopes and the intersections of linear plots of A−1 vs. Rf, (ARf)−1 vs. Rf−1, and ARf vs. A, where A is Ao (absorbance of chloroform phase), Aa (absorbance of aqueous phase), ΔA (= Ao−Aa) or ΣA (= Ao + Aa). Among them, the plots using ΣA as A gave the best results, probably due to a cancellation of the intrinsic errors in the Ao and Aa measurements. The method was simple and efficient (< 5 min/determination) with satisfactory precision.

Extraction Electrons from a Helical Device for Utilization as an Electron Source

For the purpose of making use a torus type magnetic confinement device as a high current electron source by extracting runaway electrons, we investigated magnetic fields’ configuration and calculated electron orbits by numerical simulation. Extraction coils which generate field to lead electrons to outside of the device, also strongly disturbed magnetic field in partly installed case. We propose new cancellation coil setups. The numerical calculation shows influence of extraction coils are reduced, and as a results, the maximum radius of magnetic surface is almost the same as the case of setting up extraction coils all around device.We also traced the electron acceleration and extraction orbits from low energy in confinement area. Through that, we estimated the extraction ratio of the runaway electrons and their averaged energy. The results show that 70% of the runaway electrons can be extracted and the averaged energy of those electrons is 4 keV in case of all direction extraction.

Solvent Extraction with Electrokinetic Multicommutation Analysis System

The feasibility of solvent extraction with an electrokinetic flow analysis (EKFA) system should be investigated further because of its non‐aqueous condition. As an example, the pre‐concentration and determination of copper, including on‐line color reaction, solvent extraction, and spectrometric determination were carried out by an electrokinetic multicommutation analysis system in this work. The proposed system consisted of one electroosmotic pump, four solenoid valves which were controlled by a personal computer, and a spectrometric detector. With the electroosmotic pump, sample and reagent solutions were aspirated into the system's color reaction section in small plugs, alternately, and were reacted sufficiently. Then, a plug of chloroform was inserted into the colored zone. The proposed system carried out solvent extraction by moving the sandwiched zone back and forth along its short extraction coil. After phase separation with a T‐shape separator, organic phase was determined in a flow detection cell of the spectrophotometer. The electroosmotic pump is a liquid delivery device with the merits of non‐pulsed and stable flow rate, simple pump structure, high driving efficiency, and facile flow control. Ethanol solution, a relatively high permittivity and innocuous solvent, was adopted as the pump carrier. In this paper, carrier additives were investigated further in order to improve the pump stability and efficiency (3.9 mL min−1 mA−1). The detection limit for copper was 0.03 mg L−1 (K = 3, n = 11) and its recoveries were in the range of 92–96% with a relative standard deviation of 5.2% (n = 3). The proposed method can provide a throughput of 20 samples per hour.

Modified electron cyclotron resonance source design for He3 accelerator mass spectroscopy (abstract)

The 10 GHz ECR-I ion source at ATLAS is being modified to create a small inner volume within the main plasma chamber to reduce the residual helium background gas load. This effort is part of an experiment to measure the residual concentration of He3 in highly isotopically enriched He3 samples. The modification consists of a new extractor electrode on which is integrally mounted a 2.5-cm-diam quartz tube of approximately 8 cm length. Energizing just the extraction coil produces an ECR only inside the quartz volume. The quartz tube is pumped only through the 1-mm-diam extraction hole. rf power is provided by propagation through the main plasma tank acting as a multimode waveguide. The source must operate in the pressure regime of 10–200 mTorr in order to achieve sufficient sensitivity to measure a He3/4He ratio of approximately 1×10−15. Results of these tests and the operation of the source in this highly unusual mode will be presented.