Increase In Discharge Rate Research Articles

Experimental study of dynamic melting process in an ice-on-coil storage system

Ice storage air conditioners in the field of refrigeration and air conditioning have the ability to effectively regulate the power load curve by mitigating the occurrence of high peaks and filling in the low troughs in power consumption. In order to enhance the applicability of the ice-storage air conditioner, a method of experimental analysis was utilized to incorporate a dynamic circulation system into the specially designed ice-melting ice storage tank. The system consists predominantly of circulation pumps, transportation tubes, and sprinkler nozzles. The study examined the effects of several parameters, including the arrangement of sprinkler nozzles, the flow rate of the sprinkler nozzles, the temperature of the brine at the inlet, and the flow rate of the brine, on the performance of the system. The assessment of the performance was conducted by considering the average discharge rate, total discharge capacity, duration of melting, discharge rate, and the distribution of temperature within the phase change material (PCM) tank. Based on the empirical findings, the dynamic ice melting system exhibited a notable increase in the average discharge rate, ranging from 60.7 % to 89.2 %, as compared to the static ice melting system. The duration of ice melting experienced a decrease ranging from 45.3 % to 54.3 %, while the distribution of temperature in the tank containing PCM exhibited a greater level of uniformity in comparison to the process of static ice melting. The staggered arrangement of nozzles has demonstrated superior effectiveness in terms of parameter impacts. The study revealed a positive correlation between the rate at which ice melts and the flow rate of the sprinkler, the temperature at which brine enters the system, and the rate at which brine flows.

Simulation Study on Stress-Strain and Deformation of Separator Under Battery Temperature Field

Understanding the thermal stress, thermal strain, and deformation law of separators under a battery temperature field significantly improves battery safety. This article analyzes the temperature field distribution characteristics of an NCM523 soft pack lithium-ion battery under different discharge rates, and the thermal stress, strain, and deformation laws of the separator in the battery temperature field are evaluated through numerical simulation. The results show that the tabs have the lowest temperature in the battery, and the highest temperature is observed in the middle lower part of the center section of the cell. At a constant external temperature of 300 K and a discharge rate of 0.5 C, the maximum temperature of the battery at the end of discharge is 302.402 K. As the discharge rate increases, the maximum temperature of the battery gradually increases. The distribution of the thermal stress and thermal strain of the separator is related to the distribution of the battery temperature field; where the battery temperature is high, the thermal stress and thermal strain of the separator are large. The largest deformation of the separator occurs in the corner region. Moreover, with increasing discharge rate, the expansion of the separator increases.

Thermal and stoichiometry inhomogeneity investigation of large-format lithium-ion batteries via a three-dimensional electrochemical-thermal coupling model

Large-format lithium-ion batteries (LIBs) have attracted extensive concern due to the advantages of increasing energy density and reducing manufacturing costs. However, inhomogeneity is widely present in large-format LIBs, which may lead to local degradation or edge lithium plating, thereby reducing the battery durability and safety. In this study, an electrochemical-thermal (ECT) coupling model for large-format LIBs is developed to quantitatively investigate the battery inhomogeneity during charging and discharging. First, two different sizes of batteries with the same electrode material are disassembled and tested to obtain the battery model parameters. Second, a novel method for determining the parameters of the ECT coupling model for large-format LIBs is proposed to solve the technical challenge of difficult model parameter calibration. Specifically, the ECT coupling model parameters of large-format batteries are determined using those of small-format batteries. The experimental results show that the three-dimensional ECT coupling model exhibits high accuracy, with the root mean square error of voltage and temperature within 17.8 mV and 1.27 ˚C, respectively, at 1C discharge rate and SOC greater than 2.5 %. Finally, the temperature and stoichiometry coefficient inhomogeneity of large-format LIBs during charging and discharging under different conditions are analyzed quantitatively. The results show that the inhomogeneity of large-format LIBs increases significantly with increasing discharge rate and battery length. A large-format battery with a length of 900 mm achieves a balance between inhomogeneity and length. This study contributes to a quantitative understanding of the inhomogeneity of large-format LIBs and provides a model-based perspective for designing and optimizing large-format LIBs.

Deficits in neuromuscular control of increasing force in patients with chronic lateral epicondylitis.

Objective: This study investigated the neuromuscular control of increasing and releasing force in patients with chronic lateral epicondylitis (CLE). Methods: Fifteen patients with CLE (10 males, 5 females, 46.5 ± 6.3years) and fifteen healthy participants (9 males, 6 females, 45.3 ± 2.5years) participated in this study. In addition to power grip and maximal voluntary contraction (MVC) of wrist extension, force fluctuation dynamics and characteristics of inter-spike intervals (ISI) of motor units (MUs) with various recruitment thresholds in the extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL) during a designated force-tracking task with a trapezoidal target (0%-75%-0% MVC) were assessed. Results: Besides a smaller MVC of wrist extension, the patients exhibited significantly greater task errors (p = 0.007) and force fluctuations (p = 0.001) during force increment than the healthy counterparts. Nevertheless, no force variables significantly differed between groups during force release (p > 0.05). During force increment, the amplitudes of the motor unit action potential of the ECRB and ECRL muscles of the patients were smaller than those of the heathy counterparts (p < 0.001). The patient group also exhibited a higher percentage of motor units (MU) with lower recruitment threshold (<5% MVC) in the ECRL/ECRB muscles and a lower percentage of MU with higher recruitment threshold (>40% MVC) in the ECRB muscle, compared to the healthy group. During force increment, the patient group exhibited a higher rate of decrease in inter-spike intervals (ISIs) of motor units with lower recruitment thresholds (<10% MVC) in the ECRB and ECRL muscles, compared to the control group (p < 0.005). Conclusion: The patients with CLE exhibited more pronounced impairment in increasing force than in releasing force. This impairment in increasing force is attributed to deficits in tendon structure and degenerative changes in the larger motor units of the wrist extensors. To compensate for the neuromuscular deficits, the rate of progressive increase in discharge rate of the remaining smaller motor units (MUs) is enhanced to generate force. Significance: The deficits in neuromuscular control observed in CLE with degenerative changes cannot be fully explained by the experimental pain model, which predicts pain-related inhibition on low-threshold motor units.

Experimental Study on the Effect of Sub-Flash Point Fuel Temperature on the Spread Characteristics of Spill Fire

The spill fires caused by liquid fuel leaks greatly threaten the safety of fuel transportation and storage. In this work, the effect of fuel temperature on the spread characteristics of flowing flames was investigated through n-butanol spilling fire experiments. The spill fire spread can be divided into three stages at different temperatures and leakage rates (I) full spread, (II) gradually extinguished spread, and (III) unable to spread. The oscillation of the flame is related to the fuel thickness and the discharge rate. As the discharge rate or temperature increases, the spread mode changes from pulsation to uniform. With an increase in temperature, the surface flow of the flame is reduced, leading to a decrease in both the preheating time and pulsation amplitude. However, the rate of liquid surface detachment from the flame increases with increasing temperature. The view factor of flame spread can be calculated by the solid flame model, and the flame influences the heat radiation spread state with stable phases or peaks. The research findings presented in this paper hold significant implications for the development of fire safety regulations pertaining to fuel leakage fires.

Adjustments in the motor unit discharge behavior following neuromuscular electrical stimulation compared to voluntary contractions.

Introduction: The application of neuromuscular electrical stimulation superimposed on voluntary muscle contractions (NMES+) has demonstrated a considerable potential to enhance or restore muscle function in both healthy and individuals with neurological or orthopedic disorders. Improvements in muscle strength and power have been commonly associated with specific neural adaptations. In this study, we investigated changes in the discharge characteristics of the tibialis anterior motor units, following three acute exercises consisting of NMES+, passive NMES and voluntary isometric contractions alone. Methods: Seventeen young participants participated in the study. High-density surface electromyography was used to record myoelectric activity in the tibialis anterior muscle during trapezoidal force trajectories involving isometric contractions of ankle dorsi flexors with target forces set at 35, 50% and 70% of maximal voluntary isometric contraction (MVIC). From decomposition of the electromyographic signal, motor unit discharge rate, recruitment and derecruitment thresholds were extracted and the input-output gain of the motoneuron pool was estimated. Results: Global discharge rate increased following the isometric condition compared to baseline at 35% MVIC while it increased after all experimental conditions at 50% MVIC target force. Interestingly, at 70% MVIC target force, only NMES + led to greater discharge rate compared to baseline. Recruitment threshold decreased after the isometric condition, although only at 50% MVIC. Input-output gain of the motoneurons of the tibialis anterior muscle was unaltered after the experimental conditions. Discussion: These results indicated that acute exercise involving NMES + induces an increase in motor unit discharge rate, particularly when higher forces are required. This reflects an enhanced neural drive to the muscle and might be strongly related to the distinctive motor fiber recruitment characterizing NMES+.

In-situ measurement of the heat generation of LiFePO4 and Li(Ni1/3Co1/3Mn1/3)O2 batteries

The heat flow behavior of lithium-ion batteries during normal operation is an important consideration for safety. Yet, there are few studies on this subject. In current work, the heat flow of Li(Ni1/3Co1/3Mn1/3)O2 (NCM) and LiFePO4 (LFP) batteries during a discharge and charge cycle at different ambient temperatures and discharge rates has been tested for the first time using a high precision isothermal microcalorimeter (TAM IV). The agreement of the measured heat flow over several repeated cycles is excellent, with a spike in heat flow occurring at the end of discharge. Low temperatures have a greater effect on the heat flow of the battery than high temperatures. NCM batteries have greater thermal stability than LFP batteries during heating and cooling, as well as when the discharge rate increases. Meanwhile, the heat flow spike of NCM batteries has a good exponential dependence on temperature and discharge rate. At a certain temperature, a model of the heat flow eigenvalue function, which is only dependent on the discharge rate, is developed. There is a strong correlation between the heat flow behavior and the electrical behavior of LFP and NCM batteries. The research provides a practical basis for the application, monitoring, and optimization of lithium-ion batteries.

Thermal characteristics of pouch lithium–ion battery capacitors based on activated carbon and LiNi1/3Co1/3Mn1/3O2

Lithium–ion battery capacitors (LIBCs) are internal hybrid energy storage devices that incorporate structural characteristics of lithium–ion batteries (LIBs) and lithium–ion capacitors (LICs) for extensive applications in electric vehicles and energy storage systems. But, most of the existing researches have concentrated on the electrochemical performance of LIBC cells, with less research on thermal behaviors of them. Therefore, this work systematically investigates the thermal characteristics of LIBC cells during discharge from 1C to 160C. The discharge capacity is reduced along with an increase in discharge rate, with the highest temperature occurring at 80C discharge rate, where it reaches 51.74 °C. The share of irreversible heat generation, reversible heat generation and other heat generation with respect to total heat generation are quantified. With the discharge rate increasing to 160C, the share of irreversible heat generation is nearly 89.2 % of the total heat generation. Meanwhile, it obtains 263.21 W heat generation rate. Moreover, the LIBC cell's internal resistance is obtained by intermittent current method and electrochemical impedance spectroscopy (EIS) method, while the heat generation is calculated to estimate cell's temperature rise. The intermittent current method makes possible the selection of various timescales for calculating the polarization internal resistance with more accurate calculation of the temperature rise.

Intrinsic motor neuron excitability is increased after resistance training in older adults.

This study investigated the effects of high-intensity resistance training on estimates of the motor neuron persistent inward current (PIC) in older adults. Seventeen participants (68.5 ± 2.8 yr) completed a 2-wk nonexercise control period followed by 6 wk of resistance training. Surface electromyographic signals were collected with two 32-channel electrodes placed over soleus to investigate motor unit discharge rates. Paired motor unit analysis was used to calculate delta frequency (ΔF) as an estimate of PIC amplitudes during 1) triangular-shaped contractions to 20% of maximum torque capacity and 2) trapezoidal- and triangular-shaped contractions to 20% and 40% of maximum torque capacity, respectively, to understand their ability to modulate PICs as contraction intensity increases. Maximal strength and functional capacity tests were also assessed. For the 20% triangular-shaped contractions, ΔF [0.58-0.87 peaks per second (pps); P ≤ 0.015] and peak discharge rates (0.78-0.99 pps; P ≤ 0.005) increased after training, indicating increased PIC amplitude. PIC modulation also improved after training. During the control period, mean ΔF differences between 20% trapezoidal-shaped and 40% triangular-shaped contractions were 0.09-0.18 pps (P = 0.448 and 0.109, respectively), which increased to 0.44 pps (P < 0.001) after training. Also, changes in ΔF showed moderate to very large correlations (r = 0.39-0.82) with changes in peak discharge rates and broad measures of motor function. Our findings indicate that increased motor neuron excitability is a potential mechanism underpinning training-induced improvements in motor neuron discharge rate, strength, and motor function in older adults. This increased excitability is likely mediated by enhanced PIC amplitudes, which are larger at higher contraction intensities.NEW & NOTEWORTHY Resistance training elicited important alterations in soleus intrinsic motor neuronal excitability, likely mediated by enhanced persistent inward current (PIC) amplitude, in older adults. Estimates of PICs increased after the training period, accompanied by an enhanced ability to increase PIC amplitudes at higher contraction intensities. Our data also suggest that changes in PIC contribution to self-sustained discharging may contribute to increases in motor neuron discharge rates, maximal strength, and functional capacity in older adults after resistance training.

Flexor hallucis brevis motor unit behavior in response to moderate increases in rate of force development.

Studies on motor unit behaviour with varying rates of force development have focussed predominantly on comparisons between slow and ballistic (i.e., very fast) contractions. It remains unclear how motor units respond to less extreme changes in rates of force development. Here, we studied a small intrinsic foot muscle, flexor hallucis brevis (FHB) where the aim was to compare motor unit discharge rates and recruitment thresholds at two rates of force development. We specifically chose to investigate relatively slow to moderate rates of force development, not ballistic, as the chosen rates are more akin to those that presumably occur during daily activity. We decomposed electromyographic signals to identify motor unit action potentials obtained from indwelling fine-wire electrodes in FHB, from ten male participants. Participants performed isometric ramp-and-hold contractions from relaxed to 50% of a maximal voluntary contraction. This was done for two rates of force development; one with the ramp performed over 5 s (slow condition) and one over 2.5 s (fast condition). Recruitment thresholds and discharge rates were calculated over the ascending limb of the ramp and compared between the two ramp conditions for matched motor units. A repeated measures nested linear mixed model was used to compare these parameters statistically. A linear repeated measures correlation was used to assess any relationship between changes in recruitment threshold and mean discharge rate between the two conditions. A significant increase in the initial discharge rate (i.e., at recruitment) in the fast (mean: 8.6 ± 2.4 Hz) compared to the slow (mean: 7.8 ±2.3 Hz) condition (P = 0.027), with no changes in recruitment threshold (P = 0.588), mean discharge rate (P = 0.549) or final discharge rate (P = 0.763) was observed. However, we found substantial variability in motor unit responses within and between conditions. A small but significant negative correlation (R2 = 0.33, P = 0.003) was found between the difference in recruitment threshold and the difference in mean discharge rate between the two conditions. These findings suggest that as force increases for contractions with slower force development, increasing the initial discharge rate of recruited motor units produces the increase in rate of force development, without a change in their recruitment thresholds, mean or final discharge rate. However, an important finding was that for only moderate changes in rate of force development, as studied here, not all units respond similarly. This is different from what has been described in the literature for ballistic contractions in other muscle groups, where all motor units respond similarly to the increase in neural drive. Changing the discharge behaviour of a small group of motor units may be sufficient in developing force at the required rate rather than having the discharge behaviour of the entire motor unit pool change equally.

Experimental study on the effect of ambient temperature and discharge rate on the temperature field of prismatic batteries

Lithium-ion battery surface temperature is too high or too low and poor uniformity, not only affects the performance of the battery but is also prone to thermal runaway due to local overheating of the battery. In this work, by changing the discharge rate (0.5 C, 1 C, 1.5 C, and 2 C) and the ambient temperature (−20 °C, −10 °C, 0 °C, 15 °C, 25 °C, and 35 °C), the temperature change and distribution of large capacity and large size square lithium-ion power batteries under different experimental conditions were studied. The results show that the change in battery temperature is divided into three phases. I slow rise period, II fallback period, and III rapid rise period, and with the increase of discharge rate and the decrease of ambient temperature II stage will disappear, the battery temperature change gradually shows a linear increase. As the discharge rate increases and the ambient temperature decreases, both the cell temperature rise (ΔT) and temperature difference (Δt) will become larger. In addition, whether it is the increase of the discharge rate or the decrease of the ambient temperature, a large temperature difference is easily generated in the longitudinal axis direction of the lithium-ion battery during discharge, but the temperature difference generated in the lateral axis direction is just obvious in the lower ambient temperature.

The role of entrained air from the top of the aerated bin in the discharge of cohesive powder

The effect of aeration was investigated as strong wheat flour is discharged from the orifice of open bins. If the orifice diameter is small, part of the aeration air will escape from the top of the bin, and there will be no further increase in powder discharge rate. If the orifice size is large, the additional air is entrained from the top of the bin by accompanied aeration air, and then the discharge rate will increase. The airflow at the top of the bin was estimated by two models. Two aeration methods were investigated: from the conical hopper wall and from the flat bottom. The aeration air was varied in the range up to 30L ∙ min −1 . The diameter of the cylindrical bin was 284 mm, the diameter of the orifice varied from 10 mm to 50 mm, and the flour was not discharged without aeration when the diameter was below 50 mm. • The air entrainment is estimated by two models and confirmed their correspondence. • Two aeration methods were investigated from the conical hopper and the flat bottom. • A part of the aeration air will escape from the top of the bin. • The additional air is entrained from the top of the bin by accompanied aeration air. • The driving force to the particles at the orifice collapses the static arch formation.

Improved hospital discharge and cost savings with esophageal cooling during left atrial ablation

BackgroundLeft atrial ablation to obtain pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF) is a technologically intensive procedure utilizing innovative and continually improving technology. Changes in the technology utilized for PVI can in turn lead to changes in procedure costs. Because of the proximity of the esophagus to the posterior wall of the left atrium, various technologies have been utilized to protect against thermal injury during ablation. The impact on hospital costs during PVI ablation from utilization of different technologies for esophageal protection during ablation has not previously been evaluated.ObjectiveTo compare the costs of active esophageal cooling to luminal esophageal temperature (LET) monitoring during left atrial ablation.MethodsWe performed a time-driven activity-based costing (TDABC) analysis to determine costs for PVI procedures. Published data and literature review were utilized to determine differences in procedure time and same-day discharge rates using different esophageal protection technologies and to determine the cost impacts of same-day discharge versus overnight hospitalization after PVI procedures. The total costs were then compared between cases using active esophageal cooling to those using LET monitoring.ResultsThe effect of implementing active esophageal cooling was associated with up to a 24.7% reduction in mean total procedure time, and an 18% increase in same-day discharge rate. TDABC analysis identified a $681 reduction in procedure costs associated with the use of active esophageal cooling after including the cost of the esophageal cooling device. Factoring in the 18% increase in same-day discharge resulted in an increased cost savings of $2,135 per procedure.ConclusionsThe use of active esophageal cooling is associated with significant cost-savings when compared to traditional LET monitoring, even after accounting for the additional cost of the cooling device. These savings originate from a per-patient procedural time savings and a per-population improvement in same-day discharge rate.

Comparative Study on the Outcome of Trauma Patients Transferred by Doctor Helicopters and Ground Ambulance in South Korea.

The purpose of this study was to analyze the cost-effectiveness of helicopter emergency medical services (HEMS) for its economic operations in South Korea. This study targeted trauma patients that were transported by either HEMS or ground emergency medical services (GEMS) from the scene of an accident to a regional emergency medical center. From this patient population, severe trauma patients (injury severity score ISS ≥ 16 points) with a distance travelled from the scene of the injury to the hospital that was 30 km or longer and with analyzable outcome data were extracted and included in this study. Cost-effectiveness was analyzed from survival and efficiency based on medical costs incurred from the pre-hospital setting to hospital discharge. This study included a total of 34 HEMS and 105 GEMS patients with an Injury Severity Score (ISS) ≥ 16 points from a pool of 357 potential patients. The survival-to-discharge rate of HEMS was 29 of 34 patients (85.3%) and was significantly higher than that of GEMS, where only 66 of 105 patients (62.8%) survived to discharge (P = 0.024). The expected and the actual mortality was higher in HEMS than it was in GEMS. Statistical significant difference in cost was found between the 2 groups (P = 0.002). The results of the present study indicate the increased discharge rate, survival rate and reduced in hospital mortality of HEMS with reduced admission time. This result association leads to reasonable cost effectiveness and efficient estimates overall.

Characterization of powder apparent viscosity: A reapplication of the Poiseuille equation to silo discharges

In the present work, a new method to characterize powder apparent viscosity was proposed by applying the Poiseuille equation to silo discharges. Flow properties of powders were first identified in terms of angle of repose and Hausner ratio, based on which experimental materials were classified as free-flowing and cohesive powders. These powders were further discharged from the pressurized silo, and an exponential increase in the powder discharge rate on the pressure difference was obtained. A model to predict the apparent viscosity was further developed grounded on the Poiseuille equation. The apparent viscosity of both free-flowing and cohesive powders decreases with an increasing flow rate within a specific range, showing the characteristic of shear-thinning. There was a reasonable agreement of powder apparent viscosity characterization between results from the silo discharge and those obtained from the FT4 rheometer, thus, confirming the method's reliability. The new method presented reliable values and had a wide testing range, providing an alternative way to measure powder rheological parameters.

Li4Ti5O12 Coated by Biomass-Derived Carbon Quantum Dots as Anode Material with Enhanced Electrochemical Performance for Lithium-Ion Batteries

Li4Ti5O12 (LTO) is a promising anode material for lithium-ion batteries (LIBs) due to its stable reversibility, high-rate cyclability, and high operational potential. On the other hand, it suffers from poor electronic conductivity and low capacitance. To overcome these disadvantages, modification of the LTO surface is frequently undertaken. Considering this idea, the production of a biomass-derived carbon-coated LTO material (LTO/C) and its application as an anode in LIBs is described in this work. The carbon precursor was obtained from commercial carrot juice, which was degraded using microwaves. According to the UV studies, the carbon precursor revealed similar properties to carbon quantum dots. Then, it was deposited on LTO synthetized through a sol-gel method. The LTO/C electrode exhibited a high specific capacity of 211 mAhg−1 at 0.1 C. Capacity retention equal to 53% of the initial value was found for the charge–discharge rate increase from 0.1 C to 20 C. The excellent electrochemical performance of LTO/C was caused by the carbon coating, which provided (i) short diffusion pathways for the Li+ ions into the LTO structure and (ii) enhanced electronic conductivity. The obtained results indicated that biomass-derived carbon quantum dot-coated LTO can be considered as a promising anode for LIBs.

Computational studies of hydraulic stressors for biological performance assessment in a hydropower plant with Kaplan turbine

Hydropower is currently one of the preeminent sources of renewable energy in the United States and globally. Hydropower plants also have detrimental impacts on the environment and ecology, including direct impacts to anadromous fish populations. The computational fluid dynamics (CFD) – based Biological Performance Assessment (BioPA) toolset is used for biological evaluations of fish passage through hydropower plants. The hydraulic environment of a hydropower plant was evaluated using CFD coupled with discrete element method (DEM) simulations. The predicted flow field and particle collision rate were validated against the experimental data in a water flume that has an idealized hydroturbine distributor geometry. Flow simulations were conducted to evaluate the hydraulic stressors, such as nadir pressure, fluid shear, runner collision, in a physical scale in a hydropower plant with Kaplan turbine which are responsible for injury and mortality of fish in a downstream migration. The cumulative exposure probability for the nadir pressure and collision with turbine runner was found to decrease with increased discharge rate. The lowest discharge rate shows the higher value of cumulative shear exposure probability. The maximum value of collision velocity increases with increased discharge rate. We offer the conclusions that will help in understanding various hydraulic stressors for biological assessment for environmentally sustainable hydroturbine passage.

A Coupled SWAT-AEM Modelling Framework for a Comprehensive Hydrologic Assessment

This study attempts to integrate a Surface Water (SW) model Soil and Water Assessment Tool (SWAT) with an existing steady-state, single layer, unconfined heterogeneous aquifer Analytic Element Method (AEM) based Ground Water (GW) model, named Bluebird AEM engine, for a comprehensive assessment of SW and GW resources and its management. The main reason for integrating SWAT with the GW model is that the SWAT model does not simulate the distribution and dynamics of GW levels and recharge rates. To overcome this issue, often the SWAT model is coupled with the numerical GW model (either using MODFLOW or FEFLOW), wherein the spatial and temporal patterns of the interactions are better captured and assessed. However, the major drawback in integrating the two models (SWAT with—MODFLOW/FEM) is its conversion from Hydrological Response Unit’s (HRU)/sub-basins to grid/elements. To couple them, a spatial translation system is necessary to move the inputs and outputs back and forth between the two models due to the difference in discretization. Hence, for effective coupling of SW and GW models, it may be desirable to have both models with a similar spatial discretization and reduce the need for rigorous numerical techniques for solving the PDEs. The objective of this paper is to test the proof of concept of integrating a distributed hydrologic model with an AEM model at the same spatial units, primarily focused on surface water and groundwater interaction with a shallow unconfined aquifer. Analytic Element Method (AEM) based GW models seem to be ideal for coupling with SWAT due to their innate character to consider the HRU, sub-basin, River, and lake boundaries as individual analytic elements directly without the need for any further discretization or modeling units. This study explores the spatio-temporal patterns of groundwater (GW) discharge rates to a river system in a moist-sub humid region with SWAT-AEM applied to the San Jacinto River basin (SJRB) in Texas. The SW-GW interactions are explored throughout the watershed from 2000–2017 using the integrated SWAT-AEM model, which is tested against stream flow and GW levels. The integrated SWAT-AEM model results show good improvement in predicting the stream flow (R2 = 0.65–0.80) and GW levels as compared to the standalone SWAT model. Further, the integrated model predicted the low flows better compared to the standalone SWAT model, thus accounting for the SW-GW interactions. Almost 80% of the stream network experiences an increase in groundwater discharge rate between 2000 and 2017 with an annual average GW discharge rate of 1853 Mm3/year. The result from the study seems promising for potential applications of SWAT-AEM coupling in regions with considerable SW-GW interactions.

Hydrogen charging and discharging studies on embedded cooling tube metal hydride reactor designed for fuel cell applications

In the present study, an embedded cooling tube (ECT) type metal hydride (MH) reactor has been designed, manufactured, and tested for possible integration with a low-temperature Polymer Electrolyte Membrane Fuel Cell (LT-PEMFC) at 40–60 °C. The MH reactor filled with 21.5 kg La0.9Ce0.1Ni5 has been subjected to a series of parametric tests. At 20 bar, 25 °C, the MH reactor absorbed 276.08 g hydrogen in 1129 s, accounting for 1.28 wt.% charged capacity. At 40 °C, the reactor desorbed 282.8 g hydrogen within 4860 s, which, if discharged through a mass flow controller (MFC) at a steady rate, could feed a 3.5 kW LT-PEMFC for the same duration maintaining the reactor pressure above 1 bar. An increase in discharging temperature to 60 °C showed about 54% increase in average hydrogen discharge rate. Influence of variation in heat transfer fluid (HTF) flow rate was discovered to be insignificant for both charging and discharging.

Thermal behavior analysis of lithium-ion capacitors at transient high discharge rates

As one of the prospective high-rate energy storage devices, lithium-ion capacitors (LICs) typically incorporate non-Faradaic cathodes with Faradaic pre-lithiated anodes. LICs that deliver power density at high-rate discharging process can be accompanied by overheating problems which result in capacity deterioration and lifetime reduction. Therefore, it is essential to conduct a comprehensive analysis of the heat generation of LICs. The thermal behavior of pouch lithium-ion capacitors in this work is systematically investigated at transient high-rates from 1C to 550C. The heat transfer mechanisms of each part in the overall thermal behavior are quantified in detail during discharging processes. As the discharge rate increases, the temperature curve shows an upward parabolic trend at the end of discharge, with a maximum temperature of 33.68 °C at 200C.The proportion of irreversible heat to total heat generation is close to 80 % at 550C, but the temperature at the end of discharge decreases owing to the reduced discharge time. The actually measured temperature rise is compared with the one calculated using the intermittent current method, the voltage-current (VI) characteristic method and the alternating current impedance method. It can be found that the intermittent current method calculated temperature trends are in good agreement with the measured values better than other methods, because the polarization internal resistance is significantly related to the discharge time interval. These results would provide the basis for further development of a thermal model of the cell, in order to rationally design the cooling system to avoid overheating and degradation of the cells.