Effects Of Operating Parameters Research Articles

Results in Engineering Experimental investigation of drag loss and plate separation behavior of wet clutches under external forces

Understanding the drag loss behavior of wet clutches is crucial for the development of low-loss clutch systems. For non-horizontal installation positions and non-stationary applications, external forces caused by the inclination or vehicle dynamics act on the plates. It has yet to be investigated how external forces influence the plate separation process and distribution and, subsequently, the drag loss behavior. Therefore, this study aimed to fundamentally investigate wet clutches' drag loss and plate separation behavior under the effect of external forces. The investigations were conducted in three steps. First, fundamental knowledge of the plate separation and drag loss behavior was gained. The effects of relevant design and operating parameters on the drag loss behavior were determined then. Separation springs were finally tested to avoid the influence of external forces. The drag loss and plate separation behavior were investigated on a drag torque test rig based on different clutch systems. The external forces were applied by inclining the test rig. The plate separation behavior was determined through image-based measurement of the plate movements. It was found that the plates separate under external forces and that the drag torque curve shows characteristics similar to wet clutches operated without external forces applied. The utilization of the set total clearance depends on the inclination angle. Hence, increasing the set total clearance does not generally imply lower drag losses, but increasing the inclination angle leads to higher drag losses. It was confirmed that the drag loss behavior is not influenced by external forces when using spacing elements. The findings of this study extend the existing body of literature and may support the development process of brake and clutch systems.

The peculiar role of iodides and formation of iodinated oligomer byproducts upon phenol mineralization with boron-doped diamond anode

Formation of halogenated aromatic byproducts upon electrochemical advanced oxidation processes (EAOPs) had attracted increasing concerns in recent years. However, previous correlative works mainly focused on the generation of chlorinated and brominated byproducts, and the works concerning iodinated byproducts were still missing. Herein, this research was designed to investigate the generation of iodinated aromatic byproducts (IABs) during phenol electrochemical degradation with boron-doped diamond (BDD) anode. Firstly, response surface methodology was employed to compare the effects of major operating parameters on the mineralization efficiency, and the peculiar role of iodide ions was thus identified. Next, LC/MS analysis was conducted to identify the iodinated organic byproducts. Twenty-six major IABs were identified with NaI as electrolyte, including p-iodinated phenol, 2,4-diiodophenol, and iodinated dimers and trimers with complex ether structures. These findings confirmed the critical role of active iodine species during the electrolytic oxidations, as well as the overlooked coupling reactions between iodinated phenoxy radicals. Lastly, the structural characteristics of iodinated oligomers had been compared with those of chlorinated and brominated ones. Since IABs were more genotoxic than their chlorinated and brominated analogues, their formations should be carefully treated when EAOPs were applied in environmental matrices containing free iodide ions.

An efficient low-grade thermal energy dual-driven elastocaloric cooling system: Thermodynamic cycle analysis, economic and sustainability assessment

Elastocaloric cooling is regarded as the most promising emerging refrigeration technology, with heat driven elastocaloric cycles at the forefront of research. However, existing systems often have actuators with a mass of 4–20 times that of the refrigerant, resulting in bulky structures and low thermodynamic efficiency. Enhancing system compactness and efficiency has thus become a critical research challenge. This study proposes an innovative low-grade thermal energy dual-driven elastocaloric cooling system, achieving a 1:1 mass ratio (mActuator/mRefrigerant) between the actuator and refrigerant, significantly improving system compactness and coefficient of performance while effectively reducing costs. A three-dimensional numerical and geometric model was developed to analyze the thermodynamic cycle, examining the effects of material, operational, and geometric parameters on cooling performance, and a “category-wise optimization” strategy was employed to determine optimal parameter combinations. The cost and environmental impacts of the new system were evaluated and compared with vapor-compression air conditioning. Results show that the difference in transformation temperatures between austenite and martensite phases significantly impacts cooling performance. Optimal flow rates and cycling frequencies are essential to avoid performance loss. Considering the coefficient of performance and heat transfer, a 1:1 mass ratio is optimal for geometric parameters. The system achieves a maximum coefficient of performance of 0.158, exceeding the existing two schemes by more than 2 times and 7 times, with a maximum temperature rise of 13.1 K. The proposed system is economically feasible and environmentally friendly, providing valuable theoretical foundations and technical solutions for developing sustainable alternative refrigeration technologies.

Electro-osmotic flow-based microfluidic biosensor: effect of design and operating parameters

Electro-osmotic flow-based microfluidic biosensor: effect of design and operating parameters

Nanoparticle deagglomeration driven by a high shear mixer and intensification of low-speed stirring in a viscous system

High shear mixers (HSMs), with their unique advantages of high shear forces and a wide operational range, are commonly used in nanoparticle deagglomeration. This study explores a novel approach to intensifying nanoparticle deagglomeration in a 100 mPa‧s viscous system using HSMs combined with low-speed stirring. The effects of main operating and structural parameters were experimentally investigated. The results show that the teethed HSM outperforms the blade-screen HSM, achieving a smaller attainable size (114 nm vs. 210 nm) and a higher fine particle generation fraction (46.08% vs. 18.77%). Increasing HSM size directly affects the energy input (from 6.478 MJ/kg to 31.879 MJ/kg), which influences the deagglomeration mechanism and kinetics but does not affect the smallest attainable size (117 nm). Higher solid contents improve energy efficiency, while low-speed stirring, though not altering the deagglomeration mechanism, enhances its kinetics. The process intensification factor (S) and energy efficiency factor (εm) were defined to evaluate the intensification of low-speed stirring. Increasing the impeller speed enhances this effect. The PBT impeller with a diameter ratio of 0.35 is identified as the ideal structure in this study, improving deagglomeration performance by 8.26% while reducing energy consumption by 8.3%. These results provide guidance for optimizing processes and improving deagglomeration performance through the combination of low-speed stirring in viscous systems for process industries.

An emerging route for efficient conversion of monopotassium phosphate via a pilot-scale electrodialysis metathesis

This study explores energy-efficient KH₂PO₄ (KDP) preparation, examining its implications for sustainability, and offers insights on enhancement and benefits. For the first time, electrodialysis metathesis (EDM) process was considered as a potential technique for efficient conversion and cleaner production of KDP in this study. The effects of key operational parameters including applied voltage, initial feed concentration, concentration ratio, and volume ratio on the conversion performance of EDM were systematically investigated. The promising conditions were established with an applied voltage of 2.3 V per repeating unit, a concentration ratio of 0.5 M NH4Cl to 0.6 M KCl, and a critical 1.43-fold volume ratio, yielding a high-purity KDP solution of 96.65 % at 78.52 g/L with an energy consumption rate of 0.52 KWh/kg. An economic evaluation indicates a 15.4 % cost reduction compared to the market price, presenting the EDM process as a viable and leading technology for the production of high-purity KDP.

Parameter Analysis of Anion Exchange Membrane Water Electrolysis System by Numerical Simulation

Anion exchange membrane electrolysis, which combines the advantages of both alkaline electrolysis and proton-exchange membrane electrolysis, is a promising technology to reduce the cost of hydrogen production. The present work focused on the study of the electrochemical phenomena of AEM electrolysis and the investigation of the key factors of the AEM hydrogen production system. The numerical model is established according to electrochemical reactions, polarization phenomena, and the power consumption of the balance of plant components of the system. The effects of operation parameters, including the temperature and hydrogen pressure of the electrolyzer, electrolyte concentration, and hydrogen supply pressure on the energy efficiency are studied. The basic electrochemical phenomena of AEM water electrolysis cells are analyzed by simulations of reversible potential and activation, and ohmic and concentration polarizations. The results reveal that increasing the operating temperature and hydrogen production pressure of the AEM electrolyzer has positive effects on the system’s efficiency. By conducting an optimization analysis of the electrolyzer temperature—which uses the heat energy generated by the electrochemical reaction of the electrolyzer to minimize the power consumption of the electrolyte pump and heater—the AEM system with an electrolyzer operating at 328 K and 30 bar can deliver hydrogen of pressure up to 200 bar under an energy efficiency of 56.4%.

Optimization of a cold thermal energy storage system with micro heat pipe arrays by statistical approach: Taguchi method and response surface method

Cold thermal energy storage (CTES) technology is one of effective ways to utilize renewable energy and shift peak power load. In this paper, a novel CTES device using micro heat pipe arrays is numerically studied and optimized. Firstly, the Taguchi method is adopted to quantitatively analyze the contribution ratio (CR) of fin parameters to solidification and melting time, as well as compactness factor. Fin height has the highest CR of approximately 70 % for solidification and melting time, while fin thickness with the highest CR of 58.88 % for the compactness factor. Then, the response surface method is used to uncover the interactive effects of fin parameters and operation parameters. Next, multi-criteria optimization is performed by minimizing solidification time and heat exchange temperature difference, and maximizing the compactness factor. Compared with the original structure, the solidification time of optimized structure is reduced by 26.59 % with small heat exchange temperature difference of 4 °C and great compactness factor of 0.8219. Additionally, the phase change front of the original and the optimized CTES device are compared and analyzed to further reveal the reason for the performance improvement of the device. The research results provide inspiration and data support for the practical application of CTES.

Effect of Operating Parameters and Anode Configuration on Plasma Generated by a Modular Cascaded Torch

Effect of Operating Parameters and Anode Configuration on Plasma Generated by a Modular Cascaded Torch

Exergy Optimization of a Hybrid Multi Evaporative Desalination Plant powered by Solar and Geothermal Energy

Abstract An energy and exergy analysis has been conducted on a hybrid desalination system powered by solar energy using vacuum collectors and geothermal energy. This system is specifically designed to operate under the environmental conditions of southern Tunisia. The desalination plant is mainly constituted by a solar collector field, a thermal energy storage system, a Multiple Effect Distillationunit (MED) system, an evaporative condenser, and a geothermal energy recovery system. The analysis is performed using computational code established with EES software. A parametric study is conducted to examine the effects of key operating parameters on plant performances. The operating mode is determined for winter and summer seasons. Obtained results show that thermal storage system provides thermal power permitting continuous operation for about 8 hours during the nighttime period. The storage tank is the most contributor in exergy destruction with approximately 4.3 kW in winter and 5.5 kW in summer followed by the solar collector field of about 3.6 kW in winter and 3.8 kW in summer. The exergy efficiency of the desalination effects reaches 70 % in winter and 75 % in summer. The daily production of drinking water is about 12 m3/day in winter and 14 m3/day in summer. This meets the daily drinking water needs of around 3000 persons.

Effects of multiple operational parameters on recovery efficiency of underground hydrogen storage in aquifer

Due to its unique gravimetric energy density and zero carbon emissions, hydrogen is a top priority for the development of future clean and sustainable energy systems. To satisfy energy demand, underground hydrogen storage (UHS) is being adopted. Among underground hydrogen storage sources, aquifers may be one of the best places for large-scale storage of hydrogen (H2). However, there is still lacking to understand the operational parameters of UHS, which is essential to achieve better UHS performance. In this study, operational parameters such as hydrogen production time, hydrogen injection rate, hydrogen production rate, frequency and length of cycles, shut-in period, number of wells, and spacing of wells are the focus of numerical simulations. Form the results, some insights are obtained as follows: (1) At higher hydrogen injection rates, H2 recovery performance declined due to the short contact time between hydrogen and water, as well as lateral expansion of the gas. (2) Optimizing the hydrogen production rate and ensuring sufficient production time were crucial for enhancing hydrogen production performance. (3) Shorter lengths and higher frequencies of storage cycles contributed to an increase in the cumulative hydrogen production volume. Moreover, introducing a shut-in period between the injection and production periods exhibited a detrimental effect on the performance of UHS. (4) In the dual-well configuration, cumulative hydrogen production volume and cumulative recovery efficiency experienced increases of at least 0.51 × 107 m3 and 9.27%, respectively. Concerning well spacing, its impact on the performance of UHS was slight. The effectiveness of UHS in aquifers was confirmed by these results. These understandings provide a certain basis for the optimization of operating parameters.

System-Level Dynamic Model of Redox Flow Batteries (RFBs) for Energy Losses Analysis

This paper presents a zero-dimensional dynamic model of redox flow batteries (RFBs) for the system-level analysis of energy loss. The model is used to simulate multi-cell systems considering the effect of design and operational parameters on energy loss and overall performance. The effect and contribution of stack losses (e.g., overpotential and crossover losses) and system losses (e.g., shunt currents and pumps) to total energy loss are examined. The model is tested by using literature data from a vanadium RFB energy storage. The results show that four parameters mainly affect RFB system performance: manifold diameter, stack current, cell standard potential, and internal resistance. A reduction in manifold diameter from 60 mm to 20 mm reduced shunt current loss by a factor of four without significantly increasing pumping loss, thus boosting round-trip efficiency (RTE) by 10%. The increase in stack current at a low flow rate increases power, while the cell standard potential and internal resistance play a crucial role in influencing both power and energy output. In summary, the modeling activities enabled the understanding of critical aspects of RFB systems, thereby serving as tools for system design and operation awareness.

Effect of engine parameters on the mixture distribution, performance and emission characteristics of a gasoline direct injection engine with baffles – A numerical analysis

Baffles inside the combustion chamber of internal combustion (IC) engines improve in-cylinder mixture distribution, performance, and emission characteristics. However, the effect of engine operating parameters on these aspects of the engine with baffles (EWB) remains underexplored. In this study, using computational fluid dynamics (CFD), the effects of fuel injection pressure (FIP), engine speed and load in a spray-guided, gasoline direct injection engine (GDI) are analysed and compared with the conventional engine. For the analysis, injection pressures of 30, 50, 80, and 120 bar; engine speeds of 1000, 2000, and 3000 rev/min.; and overall equivalence ratios of 0.7, 0.9, and 1.2 are considered, keeping the fuel injection timing constant. Results show that, EWB outperforms the conventional engine under various conditions considered. Also, it is found that the performance of EWB at an FIP of 30 bar is comparable to that of the base engine at an FIP of 80 bar. Additionally, the EWB exhibits better thermal efficiency across all the engine speeds and load conditions. Moreover, the HC and CO emissions of the EWB are found to be lower in most engine operating conditions. However, NOx emissions are marginally higher than those of the base engine.

Experimental Analysis of the Supercritical CO2-Based Circulation Type for the Remediation of Kilogram-Scale Soil Samples from Metal Ions

Supercritical carbon dioxide (sCO2) has been proposed as one new alternative separation medium for soil remediation due to its preferrable dissolution properties and environmentally friendly nature. This study is focused on the effects of operation parameters, such as separation pressure, temperature and processing time, on the extraction efficiency of inorganic contaminants (chromium; arsenic) from soil samples by using the newly established kilogram-scale prototype. The prototype system was operated with Cyanex 302 as a chelating agent and methanol as a co-solvent. The extraction efficiency (EE) of chromium (Cr) is experimentally identified to be 97.98% at 35 MPa and 75 °C (with 60 min processing time), while it is found to drop quickly at low temperature and pressure (only 40% under 20 MPa and 35 °C). The EE of arsenic (As) has been identified generally with high efficiency, over 95% for most cases. For chromium (Cr), 30 MPa and 55 °C or higher parameter ranges are recommended to maintain an efficiency over 90%.

Thermodynamic evaluation of a Ca-Cu looping post-combustion CO2 capture system integrated with thermochemical recuperation based on steam methane reforming

The calcium looping integrated with the chemical looping combustion (CaL-CLC) process is an efficient and cost-effective CO2 capture technology that avoids the energy-intensive air separation unit in the calcium looping (CaL) process. However, in these CaL-CLC and CaL system integration schemes, the carbonation heat is utilized for steam generation, resulting a significant temperature difference and considerable irreversible loss. To prevent temperature mismatch, this paper proposes a novel Ca-Cu looping post-combustion CO2 capture method with thermochemical recuperation based on steam methane reforming. Additionally, a novel system integrated with turbine exhaust heat recovery is introduced to effectively reduce carbon emissions from flue gas. Results show that the proposed system has superior performance compared to the reference system based on the Ca-Cu looping method. The specific primary energy consumption for CO2 avoidance decreased from 2.40 MJLHV/kg CO2 in the reference system to 2.02 MJLHV/kg CO2. Exergy analysis indicates that a total of 3.0 % reduction in exergy destruction can be achieved in chemical reaction processes and heat recovery processes, contributing to the superior performance of the proposed system. Furthermore, the effects of key operating parameters indicate that cascaded turbine exhaust recovery is essential for improving the thermodynamic efficiency of the proposed system. Overall, recovering the mid-temperature carbonation heat via thermochemical regeneration and integrating with exhaust heat recovery contribute to reducing SPECCA, thus providing a promising low-energy-consumption alternative for CO2 capture.

Effects of operational parameters on fuel gas production from DC-transferred arc plasma processing of sewage sludge

ABSTRACT In this work, a DC-transferred arc plasma reactor was used to investigate the influence of operating parameters on the process of gas production from sewage sludge treatment. By varying the operating temperature, feedstock feed rate and exhaust gas flow, the study aims to elucidate the physicochemical mechanisms during plasma treatment. The sewage sludge from the municipal wastewater treatment plant has an ash content of 40.5%, consisting mainly of Si, Al, Fe and Ca (>75%), and a complex organic fraction containing carbonyls, amines and amides. At a constant mass of feedstock (without feed rate), the gas produced by the plasma treatment was obtained with a maximum syngas fraction of 86% and a heating value of 10,000 kJ/m3, while the process operated at a constant sludge feed rate of 300 g/min increased the volumetric fraction of the syngas to 95% and the heating value to 12,000 kJ/m3.

An energy-environment coupled simulation framework for multi-scale and multi-facet evaluation of data center

This paper focuses on analyzing the thermal environment and optimizing energy consumption in data centers, which has largely omitted from previous studies. The thermal environmental of data centers is simulated and analyzed by utilizing the established “server-rack-room” multi-scale heat transfer numerical model. Based on this, the coupling simulation model of thermal environment and energy consumption in data centers is proposed to explore the relationship between them, and the corresponding optimization strategy is put forward. The energy consumption simulated by energy-environment coupled model and non-coupled model can reach a discrepancy of over 30 %, which indicates that the thermal environment impacts the power consumption of the data center significantly. Besides, the effect of several operational parameters of air conditioning system on the thermal environment and energy consumption of data center is analyzed. Through the particle swarm optimization algorithm, the optimal system parameters, which meet the requirements of thermal environment and lead to the lowest energy consumption, are found for typical cities in different climatic regions. The recommended settings include the supply air temperature of about 24 ∼ 26 ℃, the air supply volume of 8 m3/s, and the temperature difference of about 3.5 ℃ between the supply air temperature and the supply chilled water temperature. Under the optimized parameter setting, the highest temperature of server decreases to below 71 ℃, and the energy saving rate is more than 6 %.

Fabrication of boron modified bi-functional air diffusion electrode for ciprofloxacin degradation: In-situ H2O2 generation and self-activation

In order to improve H2O2 in-situ generation in electrochemical system, a boron (B) modified air diffusion electrode (B@ADE) was fabricated in the present study. Carbon black (CB) doped by B was deposited on ADE surface as catalytic layer. Performance of B@ADE with different B/C mass ratios has been investigated and 0.3 was identified as the optimal one·H2O2 yield can be achieved 204.85 mg L-1 within 45 min at 0.3-B@ADE, which was 1.51 times for that of ADE. Meanwhile, H2O2 self-activation on B@ADE surface was observed and effects of different operating parameters on •OH formation have been analyzed. XPS analyzation demonstrated that BC2O, BC2O and C=O/O-C=O were related to H2O2 generation. DFT calculation revealed that BCO2 was benefit for O2 adsorption, while BC2O promoted *OOH desorption with lower free energy barriers for H2O2 and •OH generation. Quenching experiments for ciprofloxacin (CIP) demonstrated that •OH, O2•- and 1O2 were co-existed in the system with their contribution quantified. Four possible degradation pathways were proposed through active sites identification by DFT calculation and intermediates detection by HPLC-MS/MS. Bio-toxicity analyzation results showed that the toxicity of most intermediates was lowered than CIP. These results proved that electrochemical oxidation system with B@ADE enhanced in-situ H2O2 generation and self-activation, with great potential for practical application.

CO2 absorption with polyethyleneimine solution intensified by a rotating packed bed with liquid detention

This study explored the absorption of CO2 by the polyethyleneimine (PEI) solution in a rotating packed bed (RPB). In order to boost the CO2 absorption effect, the liquid detention phenomenon in the RPB was utilized to overcome the short residence time of liquid. The effects of different operating parameters on CO2 absorption efficiency (η) and gas-phase volumetric mass transfer coefficient (KGav) in the RPB were investigated. The experimental results indicated that the RPB can greatly intensify the absorption of CO2. η and KGav increased from 3.3 % and 0.041 kmol·m−3·h−1·kPa−1 to 76.0 % and 1.634 kmol·m−3·h−1·kPa−1, respectively, as the rotational speed of the RPB rose from zero to 700 rpm with 250 mL detained liquid. It was also found that the liquid detention phenomenon can significantly elevate η and KGav as a result of extended liquid residence time and increased liquid holdup in the RPB. When the detained liquid volume increased from zero to 250 mL, η and KGav increased by 55.6 % and 113.1 %, respetively. In addition, it was observed that CO2 load in the rich PEI solution increased from 9.650 to 11.189 molCO2/kg PEI while η remained around 85 % after five cycles of absorption–desorption, suggesting an excellent cyclic stability of PEI. This work contributes to the development of viable CO2 capture technologies by intensifying the CO2 absorption process in the RPB with an efficient absorbent.

Recovery of Whey Protein by Using Microfiltration: Artificial Neural Network–Based Modeling and Effects of Different Operating Parameters

ABSTRACTMicrofiltration is one of the most suitable processes for protein recovery from whey due to its low energy consumption and lack of use of heat and chemicals. However, membrane fouling is one of the limiting factors in the microfiltration process, preventing its commercial use. In this study, an artificial neural network (ANN) based model was employed to study the effects of different operating parameters on membrane fouling in whey concentration. Trans‐membrane pressure, Reynolds number, and feed temperature were selected as the input parameters. Experimental data from the available studies were used to train the ANN. The ANN with 23 neurons gave a minimum mean squared error (MSE) for trans‐membrane pressure and Reynolds number. The ANN with seven neurons gave the minimum MSE for feed temperature. The predicted values from both ANNs well fitted with the experimental results with R2 < 0.99. Simulations showed that membrane fouling increased as flux reduction increased from 36.3% to 76.39% when trans‐membrane pressure increased from 0.5 to 2 bar. In contrast, a 19.96% reduction in flux was observed by increasing the Reynolds number from 750 to 2500. An increment of 77.37% of flux reduction was observed with increasing feed temperature from 30°C to 40°C. Simulations confirmed that transmembrane pressure, Reynolds number, and feed temperature strongly influence membrane fouling. An ANN‐based approach was the most accurate method to model membrane fouling for whey protein separation.