Efficient Collector Research Articles

Numerical analysis of a small sized water based solar photovoltaic-thermal collector

ABSTRACT Large-sized collectors suffer from heat loss from its top due to large aperture plane area. In this work, numerical investigation is performed on a small-sized solar-based photovoltaic thermal water collector using a channel type absorber to analyze its performance under different operating and ambient conditions. A 3D numerical model is developed using COMSOL multi-physics software and the thermal and hydraulic performances of the PV-T collector are carried out. The influence of Reynolds number on the Nusselt number is enumerated for a given operating temperature range and solar radiation level. The variations of PV cell temperature, channel water temperature, thermal and electrical efficiency, exergetic efficiency are studied under different mass flow rates, fluid inlet temperatures, and solar radiations, which majorly control the PV-T performance. It has been observed that with increase of Reynolds number heat transfer rate also increases, and as rate of flow increases from 0.004 kg/s to 0.08 kg/s, the electrical and thermal efficiencies also increase and achieve a maximum 89.96% and 11.47%, respectively. Moreover, uniform temperature distribution has been observed for varying mass flow rates under constant inlet temperature and solar radiation. In addition, a maximum total exergy efficiency of 14.68% is achieved at a mass flow rate of 0.02 kg/s, inlet temperature of 32°C and solar radiation of 900 W/m2. On the basis of the present investigation, a small-sized PV-T collector is recommended for future use as an efficient collector that can provide hot water and also electricity for small-scale domestic or industrial applications.

High peak settlement of Diadema antillarum on different artificial collectors in the Eastern Caribbean

The massive die-off of the herbivorous sea urchin Diadema antillarum in 1983 and 1984 resulted in phase shifts on Caribbean coral reefs, where macroalgae replaced coral as the most dominant benthic group. Since then, D. antillarum recovery has been slow to non-existent on most reefs. Studying settlement rates can provide insight into the mechanisms constraining the recovery of D. antillarum, while efficient settlement collectors can be used to identify locations with high settlement rates and to collect settlers for restoration practices. The aim of this study was to compare pre and post die-off settlement rates and to determine possible settlement peaks in the Eastern Caribbean island of St. Eustatius. Additionally, we aimed to determine the effectiveness and reproducibility of five different settlement collectors for D. antillarum. D. antillarum settlement around St. Eustatius was highest in May, June and August and low during the rest of the study. Before the die-off, settlement recorded for Curaçao was high throughout the year and was characterized by multiple settlement peaks. Even though peak settlement rates in this study were in the same order of magnitude as in Curaçao before the die-off, overall yearly settlement rates around St. Eustatius were still lower. As no juvenile or adult D. antillarum were observed on the reefs around the settlement collectors, it is likely that other factors are hindering the recovery of the island's D. antillarum populations. Of all five materials tested, bio ball collectors were the most effective and reproducible method to monitor D. antillarum settlement. Panels yielded the least numbers of settlers, which can partly be explained by their position close to the seabed. Settler collection was higher in mid-water layers compared to close to the bottom and maximized when strings of bio balls were used instead of clumps. We recommend research into the feasibility of aiding D. antillarum recovery by providing suitable settlement substrate during the peak of the settlement season and adequate shelter to increase post-settlement survival of settlers. The bio ball collectors could serve as a suitable settlement substrate for this new approach of assisted natural recovery.

A facile bottom-up strategy based on combustion-reduction toward monolithic micron/nanoporous nickel: An efficient electrode material for hydrogen evolution reaction and supercapacitor

Micron/nanoporous metals are of great importance in catalysis, sensor, and energy technologies. However, their practical application is limited because the existing fabrication approaches mainly depend on the top-down strategy, such as dealloying and template methods, which often require an introduction of sacrificial materials and an elaborate process. Herein, the Ni powders with a unique micron/nanoporous structure are achieved via a direct decomposition and reduction of NiNO3 precursor in the combustion flame. The prepared powders are applied to form monolithic micron/nanoporous nickel (MNPN) through a simple dry-press and heating treatment. The designed MNPN can serve as a robust self-supporting electrode for hydrogen evolution reaction, exhibiting a high catalytic activity with the current density of 10 mA cm−2 at overpotentials of 63 mV in 1.0 M KOH and 89 mV in 1.0 M phosphate buffer solution (PBS). Furthermore, the MNPN is also used as an efficient current collector for MNPN-MnO2 supercapacitor electrodes. The MNPN-MnO2 electrodes show a high specific capacitance of 970 F g−1 at 2 mV s−1 and outstanding electrochemical stability with retention of 103.6% after 10,000 cycles. Importantly, the work offers a reliable avenue to develop monolithic micron/nano-scale porous metals for a wide range of applications.

Environmentally Sustainable Electroplating of Selective Cobalt-Chromium Coating on Stainless Steel for Efficient Solar Collectors

Environmentally Sustainable Electroplating of Selective Cobalt-Chromium Coating on Stainless Steel for Efficient Solar Collectors

The energetic, exergetic, and mechanical comparison of two structurally optimized non-concentrating solar collectors for intermediate temperature applications

The highly efficient non-concentrating solar collector is a key component for increasing solar energy penetration at the district level, thereby achieving the “carbon neutrality” goal. The non-concentrating vacuum-type solar collector used for intermediate temperature (100–200 °C) applications is a promising technology that has not been sufficiently explored. In this paper, two structurally optimized non-concentrating solar collectors have been meticulously analyzed from the perspective of structure, energy, exergy, surface stress, etc. Firstly, an outdoor experiment is executed to exhibit their thermodynamic behavior. Thermal resistance networks before and after their structural optimization are formed and the results indicate the thermal resistance that impedes solar collector heat loss has been enhanced by 3.83 and 4.17-fold, respectively. Next, energy and exergy flow charts are established to explain the thermal performance difference and the solar energy conversion in their respective internal components. Finally, the potential room for performance enhancement is further studied via the advanced exergy analysis method which reveals that the exergy destruction can be reduced by 17.74% and 13.90%, respectively. The results are essential for the further development of non-concentrating solar collectors in intermediate temperature applications, and it is also instrumental to realizing the decarbonization in district energy supplements.

Thermal Analysis of the Solar Collector Cum Storage System Using a Hybrid-Nanofluids

The main problem in the solar energy field is the storage of thermal energy. To divert this problem, it was suggested to use a flat-plat solar collector which also serves as a storage system; this solution will reduce the size of a refrigerating machine that we are studying. A high stored energy density is only possible if we through use latent heat of phase change. Thermal analysis has been developed for this type of storage collector for near-steady state conditions using a nanofluid heat storage substance depended on KNO3–NaNO3binary salt mixture as PCM and a mix of Al2O3–SiO2as nanoparticle, from which the new Hottel-Whillier-Bliss equations have been used for efficient flat plate collector. Computations were achieved for a large variety of parameters to verify the significance of the created model.

Highly Efficient Multiscale Fog Collector Inspired by Sarracenia Trichome Hierarchical Structure (Global Challenges 12/2021)

In article 2100087, Huawei Chen and co-workers design a bionic Sarracenia trichome with an on-demand regular hierarchical microchannel to achieve excellent fog harvesting and transport properties. With the combination of a Janus membrane, a highly efficient multiscale fog collector is developed, in which a gradient high-pressure field is purposely formed to improve, by threefold, fog harvesting performance compared with a single-scale structure.

Ultrafast Nonvolatile Ionic Liquids-Based Supercapacitors with Al Foam-Enhanced Carbon Electrode.

The ultrafast frequency response supercapacitor is a promising candidate for alternating current line filtering. We report the fabrication of a special structured ionic liquid-based supercapacitor with an ultrafast response of only 1.5 ms. The three-dimensional aluminum (Al) foam in situ coated with carbon layer (∼500 nm) serves as the novel, highly efficient electrode-current collector. The high porosity (95%) of Al foam allows the rapid ion diffusion and the as-obtained Al/C interface with atomic-level mixing allows the fast electron transfer, two crucial factors for ultrafast response. Hence, it possesses an excellent specific mass capacitance of 68 mF g-1 at 120 Hz, as well as an ultrahigh rate of up to 3000 V s -1. The supercapacitors exhibit frequency modulation performance in the range of 20 kHz to 16 MHz. They exhibit the similar even better alternating current filtering performance, as compared to the commercial aluminum electrolytic capacitors, detected at 10 Hz, 60 Hz, 100 Hz and 1 M Hz. These results suggest that, although ILs have high viscosity and low ion mobility, the IL-based supercapacitor has a great potential to be used as a device for alternating current line filtering, as well as providing nonvolatile and nonflammability safety.

Niobium pentoxide nanoparticles decorated graphene as electrode material in aqueous-based supercapacitors: Accurate determination of the working voltage window and the analysis of the distributed capacitance in the time domain

This study report on the physicochemical behavior exhibited by the composite material based on niobium pentoxide nanoparticles (Nb2O5) decorated graphene (Gr) and their promising electrochemical properties in neutral aqueous supercapacitors (SCs). The Nb2O5@Gr composite showed outstanding properties where Gr contributes to electrochemical stability and ultra-fast electronic transport, while Nb2O5 offers fast and reversible solid-state surface redox reactions. Nb2O5 also works as a protective surface blocker for the carbon scaffold. A new methodology is proposed to verify the electrocatalytic activity for electrolyte decomposition in SCs. It was verified the electrocatalytic activity decreased by 7% for water splitting in the presence of Nb2O5, which boosted the overall device characteristics for the energy-storage properties. The Nb2O5@Gr composite electrode increased the energy and power densities from 4 to 18 µWh cm−3 and 0.5 to 2 µW cm−3, respectively. In addition, the cell voltage increased from 0.4 to 0.6 V, while the areal capacitance changed from 27.5 to 150 µF cm−2, and the equivalent series resistance (ESR) underwent a three-fold reduction. These promising findings are associated with synergism between the Nb2O5 nanoparticles, which conferred a pronounced pseudocapacitive contribution, while the Gr worked as an efficient nanosized and localized current collector at the active redox surface sites. These results encourage future works to explore the exciting properties of the Nb2O5@Gr composite electrode in aqueous-based SCs. The distributed capacitance in the time domain was calculated to discriminate the electrostatic and faradaic charge-storage mechanisms occurring in electrical double-layer capacitors and pseudocapacitor devices, respectively.

Study on the cell-collector-bubble interfacial interactions during microalgae harvesting using foam flotation

Foam flotation is an economical and efficient technology for microalgae harvesting. However, the mechanism of cell-collector-bubble interfacial interactions remains to be elucidated. There are two distinct hypotheses regarding the mechanism of microalgae foam flotation. In this study, the cationic surfactant N-cetyl-N-N-N-trimethylammonium bromide (CTAB), which acts as a partition between Chlorella sorokiniana cells and bubbles, is quantified and the zeta potential response of cells and bubbles after adsorption of CTAB is calculated to reveal the interfacial mechanism of the cells-collector-bubble interfacial interactions. The results indicated that more than 90% of CTAB was preferentially adsorbed on the bubbles, which reversed the surface charge of bubbles from negative (−20 mV) to positive (6.1 mV). However, only 0%–3% CTAB was observed on the microalgae cells, suggesting its limited influence on the negatively charged microalgae cells (from −22.3 to −18.6 mV). During microalgae foam flotation, the nonpolar tails of CTAB were first inserted into the bubble through hydrophobic interactions, leaving the positively charged polar heads outside; further, the CTAB-covered positively charged bubbles captured the negatively charged cells by electrostatic attraction. A feasible mechanism was proposed to understand the interfacial interaction of the microalgae cell-CTAB-bubble. By understanding the mechanism of foam flotation, efficient and cost-effective collectors and devices for microalgae harvesting using foam flotation can be developed.

Design of an efficient collector for the HIAF electron cooling system

Design of an efficient collector for the HIAF electron cooling system

Highly Efficient Multiscale Fog Collector Inspired by Sarracenia Trichome Hierarchical Structure.

Fog harvesting through bionic strategies to solve water shortage has drawn considerable attention. Recently, an ultrafast fog harvesting and transport mode was identified in Sarracenia trichome, which is mainly attributed to its superslippery capillary force induced by its unique hierarchical microchannel. However, the underlying effect of hierarchical microchannel‐induced ultrafast transport on fog harvesting and the multiscale structural coupling effect on highly efficient fog harvesting are still great challenges. Herein, a bionic Sarracenia trichome (BST) with an on‐demand regular hierarchical microchannel is designed using a one‐step thermoplastic stretching approach on a glass fiber bundle. The BST is engineered to harbor major channels confined by an inner gear pattern along with junior microchannels that are automatically assembled by the glass fiber monofilaments. The BST shows enhanced capillary condensation and fog harvesting performance, in part due to its coupling effect with a Janus membrane (JM). Hence, a highly efficient multiscale fog collector is developed, in which a gradient high‐pressure field is purposely formed to improve by threefold fog harvesting performance compared with a single‐scale structure. This easy manufacturing and low‐cost fog collector may represent a useful tool for harvesting fog water for production and living and pave the way for further investigations.

Selective collection performance of an efficient quartz collector and its response to flotation separation of malachite from quartz

In this study, laurylamine ethoxylate with fifteen ethoxylate units (LAEO-15) was employed as a quartz collector for the recovery of malachite from quartz via reverse flotation. Its collecting performance and adsorption mechanism were evaluated by flotation tests and surface analyses. The results of flotation tests suggested that LAEO-15 had an intense ability to collect quartz instead of malachite, and displayed a high flotation selectivity, which promoted the significant floatability differences of both minerals. XPS confirmed that quartz adsorbed a much larger quantity of LAEO-15 than malachite, resulting in the selective collection of quartz with LAEO-15. Zeta potential and FTIR characterization further uncovered that the strong adsorption of LAEO-15 was driven by hydrogen bonding and electrostatic attraction, while electrostatic repulsion hindered the LAEO-15 adsorption on the surface of malachite. As a result, the effective separation of malachite and quartz was realized with 20 mg/L LAEO-15 at pH 6.30 via reverse flotation, in which 92.54% of malachite was recovered and 92.72% of quartz was removed, coupled with a high SI value of 12.57 in concentrate. Therefore, compared with conventional collector dodecylamine, LAEO-15 exhibited high selectivity and purification effectiveness for the separation of malachite from quartz.

Role of decaethoxylated stearylamine in the selective flotation of hornblende and siderite: An experimental and molecular dynamics simulation study

This investigation focused on the collection performance and sorption mechanisms of decaethoxylated stearylamine (DSA) applied as a new high-selectivity hornblende collector, to further extend the use of DSA for efficiently recovering siderite from hornblende. The collecting ability of DSA to both minerals was explored via a series of flotation experiments. Flotation results illustrated that in comparison with DDA, DSA displayed an excellent collection performance for the hornblende flotation, whereas it hardly collected siderite. With 0.18 mM DSA, siderite could be efficiently separated from hornblende at pH 6.30 through reverse flotation. The selective collection mechanisms of DSA for hornblende were uncovered via surface wettability, X-ray photoelectron spectroscopy (XPS), surface electrical properties, infrared spectrum (IR) characterizations, and molecular dynamics (MD) simulations. Contact angle detection indicated that DSA strengthened the surface hydrophobicity of hornblende instead of siderite, which promoted the strong collection of hornblende. Besides, surface electrical detection and IR analyses suggested that the intense DSA sorption toward the hornblende was due to the combination of electrostatic adsorption and hydrogen bonding interaction. It was demonstrated by XPS results that larger amounts of DSA were adsorbed onto hornblende than siderite, and the O sites of hornblende were involved in electrostatic attraction and hydrogen bonding interaction. Furthermore, MD simulations further revealed that compared with siderite, the intense adsorption of DSA on the hornblende was due to the hydrogen bond and electrostatic interactions between its amino group and the hornblende surface, as evidenced by a much smaller interaction distance and very negative electrostatic energy. Therefore, DSA can be utilized as an efficient collector for collecting hornblende to achieve the desiliconization of the siderite flotation.

A self-assembly mixed collector system and the mechanism for the flotation separation of spodumene from feldspar and quartz

The mixture of dodecylamine (DDA) and α-bromododecanoic acid (α-BDDA) was used as a collector to separate spodumene from feldspar and quartz. It was found that at the condition of molar ratio of DDA: α-BDDA 1:19, the collector concentration 0.500 mmol/L, and pH 7.1, the recoveries of spodumene, feldspar, and quartz were 85.90%, 4.48%, and 3.92% respectively in single mineral micro-flotation experiments. A concentrate with a recovery of 80.00% and a Li2O grade of 6.40% was achieved at the condition of molar ratio of DDA: α-BDDA 1:19, collector concentration 0.430 mmol/L and pH 6.0 in the artificial-mixed-ore micro-flotation experiments. Meanwhile, different flotation behaviors caused by different adding sequence of flotation reagents indicated that DDA could form self-assembly structure with α-BDDA. The separation and adsorption mechanism was investigated by atomic force microscopy, contact angle, zeta potential, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy measurements and turbidity testing. The results revealed that the adsorption of the DDA/α-BDDA obviously increased the hydrophobicity of spodumene, thus led to higher recovery of spodumene. But the DDA/α-BDDA had no significant effect on the hydrophilicity of feldspar and quartz, nor on their contact angles. Thus, feldspar and quartz were sank as tailings. The DDA/α-BDDA was adsorbed on the surface of spodumene by chemisorption, and the main active sites on spodumene to react with the DDA/α-BDDA were Al. The DDA/α-BDDA was a potential selective and efficient collector to separate spodumene from feldspar and quartz at litmusless condition.

Improving Current Collection of Tubular Solid Oxide Fuel Cells

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices with solid electrolyte materials that convert chemical energy in fuels into electrical energy. Tubular SOFCs (T-SOFCs) is one of the major SOFC configurations which has the advantages of good thermal conductivity, easy to seal and shorter start-up time. However, challenges remain in effectively collecting the current inside the tubular cells. Developing an efficient, easily applicable and cost-effective collector is imperative. The properties of a desired current collector are to: reflect the fuel cell performance, be able to withstand the fuel cell’s high working temperature environment, protect the fuel cell from damage, simplify the current collector application procedure, expand the contact surface between the tube and the current collector, and save cost.We have designed a current collector and identified the materials for inside tube current collection with desired characteristics such as high temperature tolerance, low electrical resistance, and low cost. The research focused on the effectiveness of the current collector and its durability at various fuel cell operation conditions. The design achieved a peak power density at 0.7V of 0.21W/cm2 at the temperature of 700oC for a conventional tubular SOFC with material set of Ni+8YSZ‖YSZ‖LSM. Comparing to the general metal (nickel, silver) current collectors, the studied material can reduce the cost from hundreds of dollars per yard to $0.13/yard. The paper will discuss the design and the cost-effective material selection of the current collector which provides a potential path for the commercialization of tubular SOFC technology.

Improving Current Collection of Tubular Solid Oxide Fuel Cells

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices with solid electrolyte materials that convert chemical energy in fuels into electrical energy. Tubular SOFC is one of the major SOFC configurations which has the advantages of good thermal conductivity, easy to seal and shorter start-up time. However, challenges remain in effectively collecting the current inside the tubular cells. Developing an efficient, easily applicable, and cost-effective collector is imperative. The properties of a desired current collector are to: reflect the fuel cell performance, be able to withstand the fuel cell’s high working temperature environment, protect the fuel cell from damage, simplify the current collector application procedure, expand the contact surface between the tube and the current collector, and save cost. We have designed a current collector and identified the materials for inside tube current collection with desired characteristics such as high temperature tolerance, low electrical resistance, and low cost. The research focused on the effectiveness of the current collector and its durability at various fuel cell operation conditions. The design achieved a peak power density of 0.21 W/cm2 at 0.7V and 700oC for a conventional tubular SOFC with material set of Ni+8YSZ‖YSZ‖LSM. Comparing to the general metal (nickel, silver) current collectors, the material which is provided in the paper can reduce the cost from hundreds of dollars per yard to $0.13/yard. The paper will discuss the design and the cost-effective material selection of the current collector which provides a potential path for the commercialization of tubular SOFC technology.

Naturally Abundant Green Moss for Highly Efficient Solar Thermal Generation of Clean Water.

Water and energy scarcity are the challenges for humankind in the coming years. Sun is the largest source of energy available on the planet. Also, brackish seawater covers more than 70% of the surface of the planet. Therefore, combining these two valuable natural resources represents an appealing solution to overcome the problem of sweet water shortage. To achieve this goal, the missing link is to develop appropriate photothermal materials with efficient light-to-heat-to-vapor generation. In this work, green moss is introduced as a natural, eco-friendly, abundant, superhydrophilic, fast water transporter, salt rejector, and highly efficient solar collector material. Green moss, owing to its open-microgrooves, can supply adequate water to the evaporation surface, while its open capillary channels can reject the precipitated salt, allowing its reusability. The green moss solar steam generator demonstrated an outstanding solar evaporation rate of 2.61 kg m-2 h-1 under 1 sun illumination, which is much higher than other reported natural and chemically modified biomasses under otherwise similar conditions. Interestingly, upon chemical modification of the green moss surface, it is possible to increase its solar evaporation rate to >3 kg m-2 h-1. Using the moss to purify and desalinate brackish water, it was demonstrated that it has the ability to decrease salinity below the WHO standards for drinkable water.

Effect of Washing on the Electrochemical Performance of a Three-Dimensional Current Collector for Energy Storage Applications.

The development of efficient materials for energy storage applications has attracted considerable attention, especially for supercapacitors and batteries that are the most promising and important power sources in everyday life. For this purpose, a suitable and efficient current collector must be determined and its behavior with respect to various solvents when it is used as an electrode material for energy storage applications should be understood. In this work, we studied the effect of washing three-dimensional nickel foam using different concentrations of hydrochloric acid and ethanol on the surface characteristics, electrochemical behavior, and storage performance of the foam. Additionally, we observed the different types of acidic treatments that improved the electrochemical and storage performances of the three-dimensional nickel foam. The surface characterization results show that acidic conditions with a concentration of 3M changes the surface morphology from a flat/hill-like structure to a nanosheet/nanoflake-like structure without any further treatment. This structure provides a nano-channel and a large number of surface charges during the electrochemical reaction. The results of this study show that pretreatment of 3D-NF is highly important and recommended. The present work also contributes to the knowledgebase on pretreatment of 3D-NF and its optimization.

On the Kinetic Behavior of Recycling Precious Metals (Au, Ag, Pt, and Pd) Through Copper Smelting Process

The recycling and recovery of precious metals from secondary materials, such as waste-printed circuit boards, are an important area of circular economy research due to the limited existing resources and increasing amount of e-waste produced by the rapid development of technology. In this study, the kinetic behavior of precious metals Au, Ag, Pt, and Pd between copper matte and iron-silicate slag was investigated at a typical flash smelting temperature of 1300 °C in both air and argon atmospheres. SEM–EDS, EPMA, and LA-ICP-MS-advanced analysis methods were used for sample characterization. The results indicate that precious metals favor the matte phase over slag, and the deportment to matte occurred swiftly within a short time after the system had reached the experimental temperature. With increasing contact times, the precious metals were distributed increasingly into the sulfide matte. The distribution coefficients, based on experimentally measured element concentrations, followed the order of palladium > platinum > gold > silver in both air and argon, and the matte acted as an efficient collector of these precious metals. The obtained results can be applied to industrial copper matte smelting processes, and they also help in upgrading CFD models to simulate the flash smelting process more precisely.Graphical