Double Unit Research Articles

High gain and circularly polarised metasurface suspended twin port Al2O3 based antenna for mm-wave 5G communication system

Abstract This article discusses design and analysis of two-port alumina ceramic based aerial in mm-wave spectrum. Aperture coupling stimulate ceramic and produce dual fundamental orthogonal field i.e. HEM11δx and HEM11δy mode. Important features of structured aerial are: (i) designed antenna produces the circular wave within 32.65-33.25 GHz; (ii) double negative unit cell based metasurface suspension enhances the antenna’s broadsided gain to 9.0 dBi; and (iii) orthogonal arrangement of aerial ports improve the separation to over 25 dB. Experimental outcomes confirm the working spectrum of design aerial in between 32.21-33.55 GHz. Directional pattern and decent assessment of diversity parameters prepares the planned aerial appropriate for 5G communication in mm-wave regime.

A Novel Banana-Shaped Mixed-Metal Co/Fe Polyoxometalate Cluster.

The synthesis and characterization of a Co/Fe mixed-metal banana-shaped polyoxometalate with the formula [(Co2.5Fe0.5(H2O)PW9O34)2(PW6O26)]16- (Co5Fe) is reported. This transition-metal-substituted polyoxometalate readily assembles from its components in a one-pot reaction and crystallizes in the monoclinic space group P21/c. The structure of Co5Fe can be considered a double sandwich composed by two B-α-{Co2.5Fe0.5PW9O40} Keggin units, in which one coordinatively saturated octahedral metal position is equally occupied by Co(II) and Fe(III) ions with a 50 % of site occupancy. These Keggin units are linked via a hexalacunary Keggin unit {PW6O26}. Single crystal X-ray diffraction and magnetic measurements support the proposed atom arrangement within the crystal structure. Magnetic measurements of these double trimeric unit {Co2.5Fe0.5O13}2 show a combination of antiferromagnetic interactions, the presence of spin frustration, and the first-order spin-orbit coupling of Co(II) ions. Electrocatalytic water oxidation measurements show that Co5Fe displays low stability in both homogeneous and heterogeneous conditions. This is evidenced by the constant increase on the catalytic currents over time together with the appearance of polyoxometalate-derived electrode-bound species that can be responsible for the observed catalytic activity.

Experimental and numerical investigation of a double spiral tube heat exchanger in a novel composite phase change material

Phase change energy storage technology effectively harnesses energy, and phase change materials have been garnered significant attention due to their high latent heat capacity. The heat transfer capacity and phase transition of HCNT−CH3COONa·3H2O/Na2HPO4·12H2O composites in a double spiral tube heat storage unit were investigated. The effects of different flow rates and temperatures on the heat transfer characteristics of phase change materials were studied, and the thermal performance of the storage units was evaluated by calculating the power, energy and energy efficiency ratios. The phase change process of the composite during heat transfer was further revealed via simulation, and the heat storage and heat release of the composite were compared with those of other phase change materials. The results show that the effects of the flow velocity on the transformation time and power of the phase change material are negligible. However, an increase in flow rate can significantly increase the heat storage and heat release of the phase change unit. In particular, when the flow rate is 4 LPM, the energy efficiency ratio can reach 76.6 %. When the temperature increases from 80 °C to 90 °C, the melting time decreases by 30.23 %, indicating that increasing the temperature has a significant effect on the phase transition process. Through simulation calculations, the composite phase change material shows significant performance advantages under the same working conditions; its heat storage capacity is 108 % greater than that of the other materials, and the heat release capacity is 206 % greater, which indicates that it has greater energy storage and release efficiency and a better thermal energy conversion capacity. In addition, the experimental and simulation results also reveal the existence of a diagonal region of slow phase transition in the heat storage unit. In summary, this paper analyses the heat transfer performance of a double spiral tube heat storage device, provides a theoretical basis for practical application, and provides an important reference for improving the performance of a phase–change energy storage system.

Analysis of extremely low water hammer pressures of draft tubes for double units in pumped storage power stations under successive load rejection conditions

With large-scale integration of intermittent energy into power systems, the operating conditions of pumped storage power stations (PSPSs) change frequently, thereby intensifying the risk of load rejections. For multiple units sharing a water conveyance system, when one or more units reject the load, other units also reject the load after a few seconds; this is defined as successive load rejection (SLR). During SLR conditions, pumped storage units produce extreme water hammer pressures, jeopardizing the safe operation of PSPSs. This study reveals the generation mechanism of extremely low draft tube pressure (DTP) during SLR, and clarifies the generating unit and corresponding occurrence moment characteristics of the minimum DTP. The results indicated an extremely low DTP, attributed to the sharp decline in the discharge owing to increased rotational speed in unit's S-shape region and the hydraulic interference owing to the increased discharge of the other unit. When the guide vane closing time (GVCT) was short, the minimum DTP occurred in the subsequent load rejection unit (SLRU) near the first peak of its rotational speed, with the discharge of initial load rejection unit (ILRU) in the rising stage. Conversely, for a large GVCT, the minimum DTP occurred in the ILRU near the second peak of its rotational speed, with SLRU discharge in the rising stage. Finally, engineering measures to improve the extremely low DTP were proposed. Overall, the findings underscore crucial engineering insights for ensuring the safety of PSPSs under extreme conditions.

Cascade Effect of a Dimerized Thermally Activated Delayed Fluorescence Dendrimer.

Thermally activated delayed fluorescence (TADF) emitters with a high horizontal orientation are highly essential for improving the external quantum efficiency (EQE) of organic light-emitting diodes; however, pivotal molecular design strategies to improve the horizontal orientation of solution-processable TADF emitters are still scarce and challenging. Herein, a phenyl bridge is adopted to connect the double TADF units, and generate a dimerized TADF dendrimer, D4CzBNPh-SF. Compared to its counterpart with a single TADF unit, the proof-of-the-concept molecule not only exhibits an improved horizontal dipole ratio (78 %) due to the π-delocalization-induced extended molecular conjugation, but also displays a faster reversed intersystem crossing rate constant (6.08×106 s-1) and a high photoluminescence quantum yield of 95 % in neat film. Consequently, the non-doped solution-processed device with D4CzBNPh-SF as the emitter achieves an ultra-high maximum EQE of 32.6 %, which remains at 26.6 % under a luminance of 1000 cd/m2. Furthermore, when using D4CzBNPh-SF as a sensitizer, the TADF-sensitized fluorescence device exhibits a high maximum EQE of 30.7 % at a luminance of 575 cd/m2 and a full width at half maximum of 36 nm.

Cascade Effect of a Dimerized Thermally Activated Delayed Fluorescence Dendrimer

AbstractThermally activated delayed fluorescence (TADF) emitters with a high horizontal orientation are highly essential for improving the external quantum efficiency (EQE) of organic light‐emitting diodes; however, pivotal molecular design strategies to improve the horizontal orientation of solution‐processable TADF emitters are still scarce and challenging. Herein, a phenyl bridge is adopted to connect the double TADF units, and generate a dimerized TADF dendrimer, D4CzBNPh‐SF. Compared to its counterpart with a single TADF unit, the proof‐of‐the‐concept molecule not only exhibits an improved horizontal dipole ratio (78 %) due to the π‐delocalization‐induced extended molecular conjugation, but also displays a faster reversed intersystem crossing rate constant (6.08×106 s−1) and a high photoluminescence quantum yield of 95 % in neat film. Consequently, the non‐doped solution‐processed device with D4CzBNPh‐SF as the emitter achieves an ultra‐high maximum EQE of 32.6 %, which remains at 26.6 % under a luminance of 1000 cd/m2. Furthermore, when using D4CzBNPh‐SF as a sensitizer, the TADF‐sensitized fluorescence device exhibits a high maximum EQE of 30.7 % at a luminance of 575 cd/m2 and a full width at half maximum of 36 nm.

Switch Capacitor–Based High Step‐Up Three‐Port DC–DC Converter for Fuel Cell/Battery Integration

ABSTRACTAddressing issues of low input voltage in new energy generation systems such as fuel cells, a high step‐up three‐port DC–DC converter for fuel cell/battery hybrid power supply system is proposed. The proposed converter is evolved from Boost three‐port converter, and switch capacitor structure and diode capacitor voltage doubling unit are employed to achieve high voltage gain and low voltage stress. The three ports are connected to fuel cell, battery and load respectively, among which the flow of energy is realized. The steady state performance of this converter in various operating states and design of parameter are presented. Primary competitive advantages compared to similar converters include high voltage gain, continuous input current and its feature of common ground. Moreover, control strategy and compensators under three operating modes are designed to achieve stable output voltage and battery protection. Finally, a 100 W experimental prototype with 15 V input voltage and 24 V battery voltage is established to verify the stable and dynamic performance of the proposed converter.

Higher survival following transplantation with a mismatched unrelated donor with posttransplant cyclophosphamide-based graft-versus-host disease prophylaxis than with double unit umbilical cord blood in patients with acute myeloid leukemia in first complete remission: A study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

The best donor option for acute myeloid leukemia (AML) patients lacking an HLA-matched donor has remained intensively debated. We herein report the results of a large retrospective registry study comparing hematopoietic cell transplantation (HCT) outcomes between double-unit umbilical cord blood transplantation (dCBT, n = 209) versus 9/10 HLA-matched unrelated donor (UD) with posttransplant cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis (UD 9/10, n = 270) in patients with AML in first complete remission (CR1). Inclusion criteria consisted of adult patient, AML in CR1 at transplantation, either peripheral blood stem cells (PBSC) from UD 9/10 with PTCy as GVHD prophylaxis or dCBT without PTCy, transplantation between 2013 and 2021, and no in vivo T-cell depletion. The 180-day cumulative incidence of grade II-IV acute GVHD was 29% in UD 9/10 versus 44% in dCBT recipients (p = .001). After adjustment for covariates, dCBT recipients had a higher non-relapse mortality (HR = 2.35, 95% CI: 1.23-4.48; p = .01), comparable relapse incidence (HR = 1.12, 95% CI: 0.67-1.86; p = .66), lower leukemia-free survival (HR = 1.5, 95% CI: 1.01-2.23; p = .047), and lower overall survival (HR = 1.66, 95% CI: 1.08-2.55; p = .02) compared with patients receiving UD 9/10 HCT. In summary, our results suggest that transplantation outcomes are better with UD 9/10 with PTCy-based GVHD prophylaxis than with dCBT for AML patients in CR1. These data might support the use of UD 9/10 with PTCy-based GVHD prophylaxis over dCBT in AML patients lacking an HLA-matched donor.

Thermal energy storage, heat transfer, and thermodynamic behaviors of nano phase change material in a concentric double tube unit with triple tree fins

The contribution of this study is the proposal of a synergistic composite enhancement strategy involving tree fins and nanomaterials to improve the low thermal performance of phase change material (lauric acid) in a typical double tube latent heat thermal energy storage unit. The effects of nanoparticle concentrations and tree fin branching angles on the fluid dynamics, melting time, heat transfer, energy storage, and entropy generation characteristics were investigated. By employing tree fins, the melting time was respectively reduced by up to 60.20% and 36.05% compared to the finless case and the rectangular fins, while the energy storage power was respectively boosted by up to 143.36% and 37.45%. The increase of nanoparticle concentration was beneficial for melting heat transfer, and the dendritic fins with a bottom angle of 90° and a top angle of 30° yielded the highest energy storage performance. The total entropy generation of the melting process was mainly governed by the thermal entropy generation, and it showed a decreasing trend with the increase of time. In contrast to the finless configuration, the incorporation of fins diminished the integrated entropy generation value. Similarly, an elevation in nanoparticle concentration also led to a reduction of the integrated entropy generation value.

Prediction of residual life of rotating components based on adaptive dynamic weighting and gated double attention unit

Gears and bearings play vital roles as essential transmission components in mechanical drivetrains. Accurately predicting the remaining useful life (RUL) of these components is paramount to ensure optimal performance and prevent unexpected failures. To enhance the precision of RUL prediction, a novel method has been developed which involves constructing health indicators (HI) and implementing an adaptive dynamic weighting (ADW) on a gated dual attention unit (GDAU). The process commences by extracting multi-dimensional time-frequency domain features from vibration signals, which are then refined using an improved kernel principal component analysis (Adaptive Kernel Principal Component Analysis – AKPCA) to extract key components. Subsequently, the constructed HI is fine-tuned through an optimization process utilizing the exponentially weighted moving average method. Finally, the ADW strategy dynamically adjusts the input weights of the HI, and the GDAU model is employed to predict the RUL of gears and bearings. Experiment and comparison results have validated the effectiveness and advantages of the proposed method.

Structural Complexities in Sodium Ion Conductive Antiperovskite Revealed by Cryogenic Transmission Electron Microscopy.

We use low-dose cryogenic transmission electron microscopy (cryo-TEM) to investigate the atomic-scale structure of antiperovskite Na2NH2BH4 crystals by preserving the room-temperature cubic phase and carefully monitoring the electron dose. Via quantitative analysis of electron beam damage using selected area electron diffraction, we find cryogenic imaging provides 6-fold improvement in beam stability for this solid electrolyte. Cryo-TEM images obtained from flat crystals revealed the presence of a new, long-range-ordered supercell with a cubic phase. The supercell exhibits doubled unit cell dimensions of 9.4 Å × 9.4 Å as compared to the cubic lattice structure revealed by X-ray crystallography of 4.7 Å × 4.7 Å. The comparison between the experimental image and simulated potential map indicates the origin of the supercell is a vacancy ordering of sodium atoms. This work demonstrates the potential of using cryo-TEM imaging to study the atomic-scale structure of air- and electron-beam-sensitive antiperovskite-type solid electrolytes.

Strategically Developed Strong Red‐Emitting Oxyfluoride Nanophosphors for Next‐Generation Lighting Applications

AbstractRed‐emitting nanophosphors have a multirole in improvising the next‐generation bulk/micro/nano‐level lighting devices, particularly in refining white light quality and device performance. Nonetheless, it is difficult to synthesize nanosized phosphors with good yield and paralleled high absorption efficiency both in UV and blue regions, which is critical for modern lighting. Herein, new Mg14Ge4.99+σO24‐x+δFx: Mn4+ red nanoparticles with sizes below 100 nm are designed to improve not only the luminescence but also the blue light absorption. This approach has validated the applicability of red‐emitting nanophosphors into flexible UV and blue nitride nanowire light‐emitting‐diodes (LEDs), and commercial bulk LEDs, for the first time, with boosted intensity and color superiority for a variety of lighting utilizations. For these phosphor LEDs (pc‐LEDs), optimized red nanophosphor with an external quantum efficiency of ≈44.5%, color purity of ≈100%, and thermal stability of ≈72% at 150 °C is used. The optimized nanophosphor is combined with a flexible UV‐AlGaN/GaN nanowire LED and a blue‐InGaN/GaN‐LED. The resultant devices show promising red electroluminescence without any degradation at elevated currents. Finally, several unfamiliar LED packaging is designed with yellow and red phosphors implemented on 2 sets of double LED units to reach CRI > 85. The re‐premeditated LED packages are useful for high‐definition lighting.

Aerodynamic Performance and Coupling Gain Effect of Archimedes Spiral Wind Turbine Array

The Archimedes spiral wind turbine (ASWT), as a novel type of horizontal-axis wind turbine, is well suited for remote islands. To explore the aerodynamic performance and coupling gain effect of ASWT array, a three-dimensional numerical simulation was carried out using the computational fluid dynamics (CFD) method. The influence of arrangement, relative spacing, and rotation configuration on the performance of a double-unit array and triangular array is studied. The results demonstrate that, in parallel arrangements, the double unit achieve higher performance than an isolated ASWT within a specific range of parallel spacing. However, the effect of performance improvement gradually diminishes as the parallel spacing increases. In tandem arrangements, the upstream unit performance remains largely unaffected when tandem spacing exceeds 5 D, while the downstream unit’s performance declines notably with reducing tandem spacing. The downstream unit in reverse rotation configuration accrues more energy than its counterpart operating at the co-rotation configuration. In triangular arrangements, the reverse rotation configuration can achieve better performance due to the meshing effect between the wake of the upstream ASWT and the downstream ASWT. This configuration allows the array system to maintain a higher maximum power output within a smaller spacing. The research results can provide a basis and reference for designing the layout scheme of a multi-unit ASWT power station.

Evidence into practice: Changes in haploidentical versus double umbilical cord blood graft utilization for hematopoietic cell transplantation in the U.S. in relation to a pivotal randomized clinical trial.

e23306 Background: Randomized clinical trials are the “gold standard”, but expensive and not always practice changing. Umbilical cord blood (UCB) and haploidentical (haplo) are donor sources for hematopoietic cell transplant (HCT) patients who do not have a fully matched donor. The Blood and Marrow Transplant Clinical Trials Network (CTN) 1101 trial (2012-2018) compared outcomes of double UCB and haplo bone marrow (BM) transplantation. The trial showed a lower two-year overall survival after UCB compared to haplo (46% vs 57%, p = 0.04). Here, we quantified the change in graft selection in clinical practice in the U.S. after publication of the trial’s primary results. Methods: 11,190 U.S. HCT recipients 18-70 years of age who received either UCB (single or double units) or haplo transplants (BM or peripheral blood stem cells), for leukemias, lymphomas, myelodysplastic syndrome, myeloproliferative neoplasms, who reported to the Center for International Blood and Marrow Transplant Research database, were analyzed. Graft utilization was analyzed in 3 time periods: 2010-2012 (pre-study), 2013-2018 (during study), and 2019-2022 (post-study), using Chi-square test and multivariable logistic regression. Results: Over the 3 time periods, there was a practice change with an increasing proportion of haplo transplants vs UCB (32%, 68% and 91% of transplants, p < 0.001; odds ratio (OR) of 4.67 and 21.38 for during-study and post-study periods, respectively, both with p < 0.001, compared to pre-study period). Males and older patients were more likely to receive haplo (OR = 1.32, p < 0.001, and OR = 1.74, p < 0.001, respectively). Compared to White recipients, Black recipients were more likely to receive haplo (OR = 1.74, p < 0.001), whereas Asian recipients were less likely to receive haplo (OR = 0.75, p = 0.002). Hispanic recipients had a similar likelihood of receiving haplo to White patients (OR = 1.03, p = 0.665). Conclusions: Practice change toward haploidentical graft utilization had begun before the CTN 1101 trial’s publication and continued to increase over time. Black patients were more likely than White patients to receive haplo, and Asian patients were more likely than White patients to receive UCB. Availability of both UCB and haplo as alternative graft sources allowed for HCT for a diverse population. [Table: see text]

Kobellite homologues from the Boliden Au–Cu–(As) deposit, Sweden: jigsaw patterning via nanoscale intergrowths in chessboard structures

Abstract Sulfosalt assemblages in a specimen from the Boliden Au–Cu–(As) deposit in northern Sweden, comprise micrometre to nanometre scale intergrowths of Se-rich izoklakeite and tintinaite with average formulae and calculated homologue number (N) given as: (Cu1.88Fe0.18)2.06(Pb22.92Ag1.47Cd0.01Zn0.01)24.41(Sb13.12Bi8.69)21.8(S50.19Se6.43Te0.12)56.73,N = 3.83, and (Cu1.31Fe0.74)2.05(Pb10.58Ag0.18Cd0.05Zn0.02)10.83(Sb10.2Bi5.23)15.43(S32.22Se2.46)34.7, N = 2.05, respectively. Tintinaite coexists with (Bi, Se)-rich jamesonite. High-angle annular dark field scanning transmission electron microscopy (HAADF STEM) imaging reveals chessboard structures comprising PbS and SnS modules with the number of atoms in the octahedral (M) sites counted as: n1 = 18 and n2 = 8 for tintinaite and n1 = 30 and n2 = 16 for izoklakeite. The homologue number can be calculated using the formula: N = (n1/6)–1 and N = n2/4 for PbS and SnS modules giving NTti = 2 and NIz = 4. A new N = 3 homologue, defined by n = 12 and n = 24 SnS and PbS modules, respectively, is identified as single or double units within areas with intergrowths between kobellite and izoklakeite. HAADF STEM imaging also reveals features attributable to lone electron pair micelles within the Sb-rich kobellite homologues. Atomic-resolution EDS STEM chemical mapping of Pb–Bi–Sb-sulfosalts shows a correlation with crystal structural modularity. The maps also highlight sites in the SnS modules of tintinaite in which Sb > Bi. Coherent nanoscale intergrowths between tintinaite and izoklakeite define jigsaw patterns evolving from chessboard structures and are considered to have formed during co-crystallisation of the two phases. Displacement textures and crosscutting veinlets (a few nm in width) are interpreted as evidence for superimposed syn-metamorphic deformation and are associated with the redistribution of Bi and Se. Imaging and mapping using HAADF STEM techniques is well suited to characterisation of Pb–Sb–Bi-sulfosalt phases, offering largely untapped potential to unravel the evolution of chessboard structures with applications across mineralogy but also extending into allied fields.

Energy harvesting from vibrations of a beam under moving mass using auxetic cantilever beams: Theoretical and experimental investigations

Recent research aims to enhance piezoelectric energy harvesting for low-power electronic circuits like sensors and wireless systems using cantilever energy harvesters with piezoelectric substrates featuring auxetic structures such as reentrant, missing rib, and double arrowhead patterns. Employing the Wentzel–Kramers–Brillouin (WKB) method is a novel method to analyze these structures based on Euler–Bernoulli beam theory. The study comprises theoretical analysis, finite element simulations, and experimental tests. The highest power output is achieved when consecutive masses excite the bridge using the double arrowhead auxetic unit cell substrate, yielding power outputs of 1.152 μ W / N . The effect of increasing unit cells has also been investigated. Highlights Creating unique analytical methods for auxetic substrate use in energy harvesters. Analyzing three auxetic harvester substrates, emphasizing their unique performance. Auxetic harvesters were studied under various bridge simulator base excitations. The study examines three auxetic structures' effect on harvested power. Study of moving masses' influence on bridge simulator, weights, and velocities.

Single vs double umbilical cord blood transplantation in acute leukemia: Systematic review and meta-analysis

Background and aimsUmbilical cord blood transplantation (UCBT) has emerged as a promising treatment option for patients with acute leukemia needing hematopoietic stem cell transplantation. Both single (sUCBT) and double cord blood units (dUCBT) demonstrate potential benefits, but studies comparing their effectiveness have shown mixed results. This meta-analysis aimed to determine the comparative safety and efficacy of sUCBT versus dUCBT in acute leukemia patients. MethodsElectronic databases were systematically examined to identify relevant studies comparing single vs double UCBT published until November 2023. Nine studies involving 3864 acute leukemia patients undergoing UCBT were included. Outcomes analyzed were acute graft-versus-host disease (GVHD), chronic GVHD, relapse, non-relapse mortality, leukemia-free survival and overall survival. Pooled risk ratios (RR) with 95% confidence intervals (CI) were calculated using a random effects model. ResultsThe risk of Grade II-IV acute GVHD (RR 1.55, 95% CI 1.19–2.03) and Grade III-IV acute GVHD (RR 1.25, 95% CI 1.07–1.46) were significantly higher with dUCBT. Relapse risk was lower with dUCBT (RR 0.57, 95% CI 0.38–0.88) while overall survival favored sUCBT (RR 1.25, 95% CI 1.06–1.46). No significant differences were observed for chronic GVHD, non-relapse mortality or leukemia-free survival. ConclusionBoth single and double UCBT have potential as effective treatments for acute leukemia. The choice of treatment should consider various factors, including the risk of GVHD, relapse, and mortality. More research, especially randomized trials, is needed to provide definitive guidance on the optimal use of single and double unit UCBT in patients with acute leukemia.

High selectivity and anti-interference molecularly imprinted polymer based on spheroidal carbonized polymer dots for effective sulfadiazine sodium removal

Although several methods for enhancing the selectivity of molecularly imprinted polymers (MIPs) have been reported, their effects on complex substrates remain unsatisfactory. In this study, a customised 1-vinyl-3-hydroxyethylimidazolium tetrafluoroborate ionic liquid with a vinyl double bond polymerizable unit and an F-atom recognition unit was employed as a precursor carbon source to prepare unique spherical carbonised polymer dots (CPDs-F) through an incomplete carbonisation process using the one-step hydrothermal method. Then used it as a novel functional monomer, sulfadiazine sodium (SDS), as a template to synthesize the SDS-imprinted material CPDs-F@MIP in aqueous media. The results indicated that the obtained CPDs-F@MIP exhibited excellent selectivity for the template, with an imprinting factor of up to 6.39, surpassing that of the MIPs prepared with chain functional monomers 2.12–4.76 times. The selective adsorption of the template molecule, SDS (selectivity coefficient: approximately 2.615–43.149), was not significantly influenced by the coexistence of contaminants with various structural characteristics. The maximum adsorption capacity reached 61.06 mg g−1. After at least twenty applications, the adsorption capability of CPDs-F@MIP did not decrease significantly. Finally, the prepared CPDs-F@MIP were used as solid-phase extraction adsorbents in combination with high-performance liquid chromatography, and the anti-interference ability and selective adsorption performance of CPDs-F@MIP in six actual water samples were investigated. Additionally, an accurate, reliable method for detecting SDS in environmental water was established (limit of detection of 0.2 μg L−1, and the recoveries ranged from 91.79% to 111.32%). Imprinting materials prepared using spherical functional monomers significantly enhance their selective recognition ability in complex media and provide new ideas for the preparation and application of novelty imprinting materials with superior performance.

Numerical study of thermal performance of a PCM in a modifying tube-bundle latent heat thermal storage

The main aim of this study is to numerically investigate the thermal performance of a newly designed modifying tube-bundle Latent Heat Thermal Storage (LHTS). The new LHTS design proposed a half-cylindrical tube attached to the Heat Transfer Fluid tube, which implies making the PCM indirect contact with the HTF tube. This reduces the heat transfer resistance by eliminating the metal construction of the tubes. For this purpose, a 3D numerical model was developed based on mass, momentum and energy conservations using ANSYS Fluent software. After validating the model developed by comparing numerical results with those obtained experimentally by a published study, the PCM liquid fraction and amount of power stored during the melting and solidification were studied. Water and lauric acid as a working fluid and PCM were implemented in the model. In addition, three different Heat Transfer Fluid (HTF) inlet temperatures 15°C,20°Cand25°C, and HTF’s flow rates in terms of Reynolds number 1000,1500and2000 were tested. The thermal behaviour of the present LHSU design was compared with that of the same volume double pipe LHTS unit. Results showed that the melting and solidification processes of the proposed storage were very uniform, with convection and conduction heat dominating PCM melting and solidification, respectively. The increase in the heat transfer contact area between the HTF and the tube bundle contributed significantly to the PCM melting and solidification acceleration, making each tube bundle behave as a single storage unit. Therefore, the time required for complete melting and solidifying of the PCM was half (50%) of the time needed for the same amount in the double pipe LHTS. Similarly, the melting and solidification time in the preset storage was shortened by about 22% and 41.6%, respectively, compared with the regular tube LHTS unit.

Performance of a rotating latent heat thermal energy storage unit with heat transfer from different surfaces

Due to the rapid growth in the demand for fast and efficient latent heat thermal energy storage system, multiple heat transfer enhancement techniques have been proposed and widely investigated. Actively or passively, rotation of the energy storage unit affects the internal natural convection and the heat transfer performance. Hence, this study is conducted to evaluate the potential of the heat transfer enhancement by rotation. A two-dimensional model with the phase change material filled in the annular space of a double tube energy storage unit is developed. The numerical simulations for the heat transfer through the internal or external surfaces of the annular space are respectively conducted. Both solidification and melting of the phase change material are taken into account by the enthalpy-porosity method. According to different heat transfer surfaces and the occurrence of solidification or melting, four arrangements are formed. It is found that the rotation of the thermal energy storage unit can reduce the solidification time as high as 46 % compared to its still counterpart, but variation of the rotation speed only produces a minor influence. The effect of rotation on the melting depends on the heat transfer direction (or surface). When the heat is transferred into the solid phase change material through the internal wall, the melting time can be gradually reduced as the rotation speed increases with a maximum of 69 %. However, when the heat is transferred through the external wall, influence of the rotation results in adverse effect. This study can guide the design of innovative high performance latent heat thermal energy storage system containing rotation unit.