Study of flow over piano key weir of different plan shapes with free and partially submerged outlet conditions

Piano key weirs are being increasingly used for better flood passage downstream, both as a new structure or on top of hydraulic structures like a dam, to increase their discharging capacity as well as reservoir storage. Much research has been done on rectangular plan-form while other plan-forms warrants attention. The present study focuses on two different plan geometries of PKW, i.e., rectangular (RPKW) and trapezoidal with angle α equal to 9 degrees (TPKW9) for their head discharge relation in a wide channel of 0.984 m width under free-flow condition. Since the role of CFD is increasingly becoming prominent in present times, a numerical study using ANSYS-FLUENT was also carried out to ascertain its relevance in predicting flows around complex structures like PKW. Further, the tailgate was closed to render the PKW's outlet from partial to fully submerged conditions. The effect of these submerged outlets was studied for any changes in the discharging capacity of the PKW. The study shows RPKW to be hydraulically efficient than TPKW9 for the model geometry. Furthur the study finds that under partial to full submergence of PKW outlets, both PKW units' discharging capability remains unchanged.

FABRICATION AND ELECTROCHEMICAL PERFORMANCE OF LiFePO4/Ga-LLZO/Li ALL-SOLID-STATE LITHIUM BUTTON CELL

An all-solid-state Lithium button cell with Ga-doped Li7La3Zr2O12 (Ga-LLZO) as solid electrolyte, LiFePO4-based as cathode, and Li metal as anode has been successfully fabricated and characterized. The solid electrolyte was first optimized to obtain a high total conductivity. Different compositions of Li7-3xGaxLa3Zr2O12, where x =0, 0.1, 0.2, and 0.3. Li7La3Zr2O12 (LLZO) were synthesized using solid-state reaction and were characterized for its structural, morphological, electrical conductivity properties. XRD patterns of all sintered samples showed that all of the major peaks can be indexed to a cubic-phased garnet LLZO. SEM images revealed a densified sintered samples with relative densities of about 90% for all samples. Among the different studied compositions, the Ga-doped LLZO with x = 0.1 achieved the highest total conductivity of about 2.03 x 10-4 Scm-1 at 25oC, with an activation energy of 0.31 eV. From this solid electrolyte, an all-solid-state Lithium battery, 2032 button cell, was fabricated using LiFePO4-based cathode and Lithium metal as the anode. Charging and discharging characteristics were performed at 1C, 0.5C, and 0.2C rates. The results showed a good retention of coloumbic efficiency even after 50 cycles of charge and discharge. The capacity retention is about 15-20% after 50 cycles. The best performance of the coin cell battery revealed an initial specific discharging capacity of about 140 mAh/g using C/5 rate.

Studi Kelajuan Elektrolit Terhadap Kapasitas Baterai Dinamis Asam Timbal Sel Tunggal

<p class="AbstractEnglish"><strong>Abstract:</strong> Electrolyte flow rate is one of the important parameters on Redox Flow Battery (RFB) performance. A single cell lead acid battery has been made with the RFB system by giving 4 variations in flow speed (45 mL/min, 77 mL/min, 90 mL/min and 105 mL/min), two electrolyte concentrations (30% and 40%) and applied 1 A of charging-discharging current with the aim of an88ukmalyzing the relationship of the electrolyte flow rate of the battery to the RFB system capacity. The results showed that the flow of electrolytes from tanks outside the cell battery was able to increase battery capacity by increasing the number of spontaneous redox reactions during charging and discharging. The cycle time and battery capacity increase at the beginning of the filling-emptying cycle but have a downward trend with the increasing number of cycles. Batteries with an electrolyte concentration of 30% and speeds of 90 mL/mnt have the best performance in terms of discharging capacity compared to other batteries.</p><p class="AbstrakIndonesia"><strong>Abstrak:</strong> Laju aliran elektrolit adalah salah satu parameter penting pada kinerja Redox Flow Battery (RFB). Baterai asam timbal sel tunggal telah dibuat dengan sistem RFB dengan memberikan 4 variasi kelajuan aliran (45 mL/mnt, 77 mL/mnt, 90 mL/mnt dan 105 mL/mnt), dua konsentrasi elektrolit (30% dan 40 %) dan diterapkan 1 A arus pengisian-pemakaian dengan tujuan menganalisis hubungan laju aliran elektrolit baterai dengan kapasitas sistem RFB. Hasil penelitian menunjukkan bahwa aliran elektrolit dari tangki di luar baterai sel mampu meningkatkan kapasitas baterai dengan meningkatkan jumlah reaksi redoks spontan selama pengisian dan pemakaian. Waktu siklus dan kapasitas baterai meningkat pada awal siklus pengisian-pengosongan tetapi memiliki tren menurun dengan meningkatnya jumlah siklus. Baterai dengan konsentrasi elektrolit 30% dan kelajuan 90 mL/mnt memiliki kinerja terbaik dalam hal kapasitas pemakaian dibandingkan baterai lainnya.</p>

Experimental and Numerical Study on Energy Piles with Phase Change Materials

Phase change materials (PCM) utilization in energy storage systems represents a point of interest and attraction for the researchers to reduce greenhouse gas emissions. PCM have been used widely on the interior or exterior walls of the building application to optimize the energy consumption during heating and cooling periods. Meanwhile, ground source heat pump (GSHP) gained its popularity because of the high coefficient of performance (COP) and low running cost of the system. However, GSHP system requires a stand-by heat pump during peak loads. This study will present a new concept of energy piles that used PCM in the form of enclosed tube containers. A lab-scaled foundation pile was developed to examine the performance of the present energy pile, where three layers of insulation replaced the underground soil to focus on the effect of PCM. The investigation was conducted experimentally and numerically on two identical piles with and without PCM. Moreover, a flow rate parametric study was conducted to study the effect of the working fluid flow rate on the amount of energy stored and released at each model. Finally, a comprehensive Computational fluid dynamic (CFD) model was developed and compared with the experimental results. There was a good agreement between the experimental measurements and the numerical predictions. The results revealed that the presence of PCM inside the piles increased not only the charging and discharging capacity but also the storage efficiency of the piles. It was found that PCM enhances the thermal response of the concrete during cooling and heating processes. Although increasing the flow rate increased charging and discharging capacity, the percentage of energy stored/released was insignificant compared to the flow rate increasing percentage.

2D hybrid nanostructures of MoSe2⊥sisal fiber activated carbon for enhanced Li storage performance

An originality hibrid nanostructure of MoSe2 nanosheets developed in the vertical direction in two-dimensional (2D) mesoporous nanosheets surface of sisal fiber activated carbon (MoSe2⊥SFAC) was obtained through hydrothermal and annealed processes. The microscopic size is about 10 nm and 1-nm-thick MoSe2 nanosheets. The novel nanostructure of MoSe2⊥SFAC shows a high specific surface area and mesoporous feature, which displays great application prospects in lithium ion batteries (LIBs). The MoSe2⊥SFAC electrode remains a detailed discharging capacity reaching 501.3 mAh g-1 at 0.1 A g-1 after 50 cycles, and 224.6 mAh g-1 at 1 A g-1 over 500 cycles, with corresponding coulombic efficiency closing to 100%. In contrast to the pure sisal fiber activated carbon, MoSe2⊥SFAC has a higher lithium ion diffusion coefficient, thus ensuring the rapid transmission of lithium ions.

A Review of Pulsed Current Technique for Lithium-ion Batteries

Lithium-ion (Li-ion) batteries have been competitive in Electric Vehicles (EVs) due to their high energy density and long lifetime. However, there are still issues, which have to be solved, related to the fast-charging capability of EVs. The pulsed current charging technique is expected to improve the lifetime, charging speed, charging/discharging capacity, and the temperature rising of Li-ion batteries. However, the impact of the pulsed current parameters (i.e., frequency, duty cycle, and magnitude) on characteristics of Li-ion batteries has not been fully understood yet. This paper summarizes the existing pulsed current modes, which are positive Pulsed Current Mode (PPC) and its five extended modes, and Negative Pulsed Current (NPC) mode and its three extended modes. An overview of the impact of pulsed current techniques on the performance of Li-ion batteries is presented. Then the main impact factors of the PPC strategy and the NPC strategy are analyzed and discussed. The weight of these impact factors on lifetime, charging speed, charging/discharging capacity, and the temperature rising of batteries is presented, which provides guidance to design advanced charging/discharging strategies as well as to determine future research gaps.

Overcoming Practical Barriers in Reconditioning Li-Polymer Batteries

In this paper, two case studies regarding the application of a reconditioning procedure of aged lithium-polymer batteries used to power a notebook and a tablet are presented. The parameters measured in the evaluating the performance of the reconditioned rechargeable batteries are the charging/discharging capacity and the internal resistance. The results obtained indicate a high degree of reconditioning of the investigated batteries, expressed as a reconditioning coefficient, calculated on the basis of the measured nominal capacities after applying the reconditioning procedure with respect to the initial one.

Flow Over Side Weirs with Experimental & CFD Results

In irrigation, sewer systems and drainage engineering side weirs are used to as a hydraulic control structure from many decades. Labyrinth side weir is a side weir with increased crest length due to folding in plan view as it provides additional length for a given opening. As a flow diversion structure in irrigation, land drainage, urban sewage systems and in intake structures. Labyrinth side weirs can be used more efficiently than conventional side weirs. In this review paper some investigations of researchers with different parameter affecting coefficient of discharge and discharging capacity of side weirs are presented. In review it seems that different parameters are affecting on discharge of side weir has been considered in empirical equations given by researcher but few parameters are left for consideration. In this paper effect of additional parameters like side weir thickness and submergence condition is evaluated by CFD mo

Accelerated Microbial Reduction of Azo Dye by Using Biochar from Iron-Rich-Biomass Pyrolysis

Biochar is widely used in the environmental-protection field. This study presents the first investigation of the mechanism of biochar prepared using iron (Fe)-rich biomass and its impact on the reductive removals of Orange G dye by Shewanella oneidensis MR-1. The results show that biochars significantly accelerated electron transfer from cells to Orange G and thus stimulated reductive removal rate to 72–97%. Both the conductive domains and the charging and discharging of surface functional groups in biochars played crucial roles in the microbial reduction of Orange G to aniline. A high Fe content of the precursor significantly enhanced the conductor performance of the produced biochar and thus enabled the biochar to have a higher reductive removal rate of Orange G (97%) compared to the biochar prepared using low-Fe precursor (75%), but did not promote the charging and discharging capacity of the produced biochar. This study can prompt the search for natural biomass with high Fe content to confer the produced biochar with wide-ranging applications in stimulating the microbial reduction of redox-active pollutants.

A Coupled Mechanical–Electrochemical Study of Li-Ion Battery Based on Genetic Programming and Experimental Validation

Lithium-ion batteries (LIBs) are the heart of electric vehicle because they are the main source of its power transmission. The current scientific challenges include the accurate and robust evaluation of battery state such as the discharging capacity so that the occurrence of unforeseen dire events can be reduced. State-of-the-art technologies focused extensively on evaluating the battery states based on the models, whose measurements rely on determination of parameters such as the voltage, current, and temperature. Experts have well argued that these models have poor accuracy, computationally expensive, and best suited for laboratory conditions. This forms the strong basis of conducting research on identifying and investigating the parameters that can quantify the battery state accurately. The unwanted, irreversible chemical and physical changes in the battery result in loss of active metals (lithium ions). This shall consequently result in decrease of capacity of the battery. Therefore, measuring the stack stress along with temperature of the battery can be related to its discharging capacity. This study proposes the evaluation of battery state of health (SOH) based on the mechanical parameter such as stack stress. The objective of this study will be to establish the fundamentals and the relationship between the battery state, the stack stress, and the temperature. The experiments were designed to validate the fundamentals, and the robust models are formulated using an evolutionary approach of genetic programming (GP). The findings from this study can pave the way for the design of new battery that incorporates the sensors to estimate its state accurately.