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The power battery configuration of an extended-range electric vehicle directly affects the overall performance of the vehicle. Optimization of the output voltage of the power battery can improve the overall power and economy of the vehicle to ensure its safe operation. Factors affecting the output voltage of power batteries under different operating conditions, such as nominal voltage and the number of series and parallel connections of the battery cells, have been studied. This study uses AVL Cruise to establish an overall model of an extended-range electric vehicle to simulate the output voltage characteristics under the different operating conditions of the NEDC (New European Driving Cycle), WLTC (World Light Vehicle Test Cycle) and CLTC (China Light Duty Vehicle Test Cycle). The influence of the output voltage of the power battery under different operating conditions is studied to ensure that the power battery can output energy with high efficiency. The operating conditions have an impact on the output voltage with an idle voltage fluctuation of the operating conditions. The nominal voltage variation and the number of series and parallel connections of the battery cells affect the frequency and time of breakdown. [ABSTRACT FROM AUTHOR]

Due to high greenhouse gas emissions, countries worldwide are stepping up their emission reduction efforts, and the global demand for new, carbon-free fuels is growing. Ammonia (NH3) fuels are popular due to their high production volume, high energy efficiency, ease of storage and transportation, and increased application in power equipment. However, their physical characteristics (e.g., unstable combustion, slow flame speed, and difficult ignition) limit their use in power equipment. Based on the structural properties of the power equipment, NH3 fuel application and emissions characteristics were analyzed in detail. Combustion of NH3 fuels and reduction measures for NOx emissions (spark plug ignition, compression ignition, and gas turbines) were analyzed from various aspects of operating conditions (e.g., mixed fuel, fuel-to-exhaust ratio, and equivalence ratio), structure and strategy (e.g., number of spark plugs, compression ratio (CR), fuel injection, and ignition mode), and auxiliary combustion techniques (e.g., preheating, humidification, exhaust gas recirculation, and secondary air supply). The performance of various NH3 fuel cell (FC) types was analyzed, with a focus on the maximum power achievable for different electrolyte systems. Additionally, the application and NOx emissions of indirect NH3 FCs were evaluated under flame and catalytic combustion conditions. The system efficiency of providing heat sources by burning pure NH3, anode tail gas, and NH3 decomposition gas was also compared. Based on a comprehensive literature review, the key factors influencing the performance and emissions of NH3-powered equipment were identified. The challenges and limitations of NH3-powered equipment were summarized, and potential strategies for improving efficiency and reducing emissions were proposed. These findings provide valuable insights for the future development and application of NH3 FCs. [ABSTRACT FROM AUTHOR]

The reliability of a car engine is ensured by the combination of oil properties that are laid in the oil production process. The properties of engine oil change with the mileage of the car compared to the initial state. When the rejection parameters of the oil reach the limit level, then it is necessary to replace the old oil with a new one. The rate of change intensity in the properties of particular oil depends on both the make of the vehicle and the operating its conditions. In difficult conditions of operation of the car, it is necessary to reduce the run period of between oil changes. But if the car is operated in light or gentle conditions, then the normative oil change may not realize its full potential. In this case, extending the oil change intervals beyond the norm leads to an increase in the efficiency of its use, which reduces the overall operating costs. It will be optimal when the service life of the oil will be determined by the actual state of the basic properties. The paper presents the results of experimental studies on changes in the concentration and rate of iron entry into motor oil. In addition, other indicators of oil in samples were determined: the viscosity, the flash point in an open crucible, the dielectric constant, the acidity and alkali numbers. The study involved motor oils of the same group, but from different manufacturers, for various brands of trucks and cars at different stages of the life cycle. The energy loading on the engine can be estimated by fuel consumption, which depends on the operating speed or operating conditions of the vehicle. An analysis of the results experiment was carried out, which established a relationship between the concentration of iron in oil and fuel consumption or car mileage. In conclusion, recommendations are given on the values of indicators at which further operation of oils is not recommended. [ABSTRACT FROM AUTHOR]

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The current study is basically focused on investigating the possible ways to enhance the lubricating oil film performance and hence ship energy efficiency of marine journal bearings in general terms. For the intended purpose, a novel numerical Circumferential Grooved Bearing (CGB) model was developed to assess journal bearing operating conditions based on versatile simulation analyses. Prior to all conducted test trials, the model validation has been confirmed based on the conformity between numerical outcomes and those derived from experimental procedures depending on Universal Journal Bearing Test Rig. CGB performance was evaluated at slow speed variations from 25 rpm up to 125 rpm and different applied loads utilizing the two lubricant oil grades of 5W40 and 0W30. Reducing shaft rotational speed by 80% was found to incur a reduction in the maximum oil film pressure value by 1.17 bar and 0.97 bar for the two aforementioned lubricants respectively. Further, the increase of applied loads from 1079 N up to 1471 N at a constant speed of 75 rpm reduces the maximum oil film pressure ratio by 0.14 and 0.18 for the two oil grades subsequently. [ABSTRACT FROM AUTHOR]

Currently, energy generation based on fossil fuels is producing negative environmental impacts; two of the main symptoms of these impacts are water pollution and climate change. Consequently, the search for new technologies to satisfy the energy demand must have the goal to minimise possible impacts to the environment. There are alternatives with biofuels and, among them, biodiesel. The cheapest reaction pathway for biodiesel production is the transesterification of triglycerides by methanol in the presence of sodium hydroxide; however, this option can contaminate large volumes of water used in the final leach of the biodiesel product. Therefore, a feasible way of producing this biofuel while simultaneously minimising leaching water will be environmentally friendly and will improve economical savings. The present study developed an experimental design in order to minimise the addition of NaOH during biodiesel production by the basic homogeneous pathway. The best operating conditions were 46 °C, methanol in situ 7.5% v/v and NaOH 0.035 M. These conditions allowed to reduce the leaching water amount by 25% compared to techniques reported in the literature; however, the yield to biodiesel decreased from 98 wt.% to 87 wt.% when a model waste oil was used instead of virgin oil. [ABSTRACT FROM AUTHOR]

Optimizing traffic signals to improve traffic progression relies on minimizing mobility performance measures (e.g., delays and stops). However, delay and stop minimizations do not necessarily lead to minimal sustainability measures (e.g., fuel consumption and emissions). For that reason, researchers have focused, for decades, on integrating traffic models, signal optimization models, and fuel consumption and emissions models to minimize sustainability metrics while keeping acceptable levels of mobility metrics. Therefore, this paper reviews, classifies, and analyzes studies found in the literature regarding optimizing sustainable traffic signals. This paper provides researchers with a good starting point to further develop solutions which can address sustainable traffic control. To achieve that, this study details the most notable sustainable signal timing optimization studies from six perspectives: traffic models, fuel consumption and emissions models, optimization methods, objective functions, operating conditions, and reported sustainability savings. Outcomes of this research show that the previous studies deployed many combinations of elements from the six-perspective mentioned above, leading to a wide range of fuel consumption and emissions savings. The study also concludes that the available fuel consumption and emissions models are relatively old. Hence, future research is needed to develop new fuel consumption and emissions models based on recently collected data. [ABSTRACT FROM AUTHOR]

• Optimal operating conditions of microbial electrosynthesis were potential 3.0 V and pH 6.0. • The utilization of substances can be controlled by controlling the potential and pH. • In response to changes in conditions, low internal resistance and electrochemical active biofilm formed, and acetic acid-forming genera were enriched. Microbial electrosynthesis (MES) is facing a series of problems including low energy utilization and production efficiency of high value-added products, which seriously hinder its practical application. In this study, a more practical direct current power source was used and the anaerobic activated sludge from wastewater treatment plants was inoculated to construct the acetic acid-producing MES. The operating conditions of acetic acid production were further optimized and the specific mechanisms involving the substance utilization and microbial response were revealed. The optimum conditions were the potential of 3.0 V and pH 6.0. Under these conditions, highly electroactive biofilms formed and all kinds of substances were effectively utilized. In addition, dominant bacteria (Acetobacterium , Desulfovibrio , Sulfuricurvum , Sulfurospirillum , and Fusibacter) had high abundances. Under optimal conditions, acetic acid-forming characteristic genera (Acetobacterium) had the highest relative abundance (Biocathode-25.82 % and Suspension-17.24 %). This study provided references for the optimal operating conditions of MES and revealed the corresponding mechanisms. [ABSTRACT FROM AUTHOR]

The proposed formula derived considering the physical phenomena which occur during truck operation makes it possible to calculate fuel cost during the operation more accurately. The results of comparison of calculations by the proposed formula with test results tractors parties "TransEuroTest" are presented. The results of the calculation with the help of new formula differ from the experimentally obtained values of the fuel consumption of vehicles for not more than 1%. The average fuel consumption of tractors at an average speed is shown. The proposed formula for calculating the cost makes it easy to compare the fuel consumption of different vehicle options. The formula can also be used when evaluating the effect of vehicle weight on fuel consumption, which is impossible according to the well-known formulas. [ABSTRACT FROM AUTHOR]

In this paper, a mathematical model is developed to study the performance of a polymer membrane electrolyser (PEM) and the effect of different parameters including operating temperature, cathode pressure, membrane thickness, the width and height of channel and current density on the performance and energy and exergy efficiency of PEM electrolyser are investigated. In addition to the resistance overvoltage of components, the concentration overvoltage is modeled using an accurate equation. The model is validated against experimental data. The results indicate that by increasing current density, the voltage of the electrolyser increases, and energy and exergy efficiencies reduce. Increase of temperature from 313 K to 353 K, and decrease of cathode pressure from 40 bar to 1 bar lead to decrease of voltage of the PEM electrolyser by 8.3% and 4.8%, respectively. Moreover, energy and exergy efficiencies increase between 2% and 6% in the range of working temperature and pressure. It is concluded that decrease of membrane thickness, height and width of channel, and increase of exchange current density of the anode and cathode electrodes lead to decrease of voltage of the electrolyser and increase of energy and exergy efficiencies. However, the effect of temperature and cathode pressure and the exchange current densities is greater than the effect of geometric parameters. • The performance of a PEMEC is investigated using a mathematical model. • The effect of different operating conditions and geometric parameters are analyzed. • Working temperature has greater effect on exergy efficiency than other parameters. [ABSTRACT FROM AUTHOR]

Abstract Anodic fuel recirculation system has a significant role on the parasitic power of proton exchange membrane fuel cell (PEMFC). In this paper, different fuel supply systems for a PEMFC including a mechanical compressor, an ejector and an electrochemical pump are evaluated. Furthermore, the performances of ejector and electrochemical pump are studied at different operating conditions including operating temperature of 333 K–353 K, operating pressure of 2 bar–4 bar, relative humidity of 20%–100%, stack cells number from 150 to 400 and PEMFC active area of 0.03 m2–0.1 m2. The results reveal that higher temperature of PEMFC leads to lower power consumption of the electrochemical pump, because activation over-potential of electrochemical pump decreases at higher temperatures. Moreover, higher operating temperature and pressure of PEMFC leads to higher stoichiometric ratio and hydrogen recirculation ratio because the motive flow energy in ejector enhances. In addition, the recirculation ratio and hydrogen stoichiometric ratio increase, almost linearly, with increase of anodic relative humidity. Utilization of mechanical compressor leads to lower system efficiency than other fuel recirculating devices due to more power consumption. Utilization of electrochemical pump in anodic recirculation system is a promising alternative to ejector due to lower noise level, better controllability and wide range of operating conditions. Highlights • The performance of PEMFC with different anodic recirculation device are investigated. • Utilization of electrochemical pump in anodic recirculation system is advantageous. • Electrochemical pump is compared with ejector and mechanical compressor. • The effects of operating and geometric conditions of PEMFC are considered. [ABSTRACT FROM AUTHOR]

Abstract Low energy consumption and less fouling propensity of forward osmosis (FO) processes have been attractive as a promising water filtration technology. The performance of this process is however significantly influenced by its operating conditions. Moreover, these operating parameters have both favourable and adverse effects on its performance. Therefore, it is very important to optimize its performance for efficient and economic operation. This study aims to develop a software to analyze a full-scale FO system for optimum performance. A comprehensive theoretical framework was developed to estimate the performance of FO system. Analysis results were compared with the experimental results to validate the models. About 5% deviation of simulation results and the experimental findings shows a very good agreement between them. A novel optimization algorithm was then developed to estimate the minimum required draw solution (DS) inlet flowrate and the number of elements in a pressure vessel to attain the design objectives (i.e. desired final DS concentration and recovery rate at a specific feed solution (FS) flowrate). A detailed parametric study was also conducted to determine the optimum operating conditions for different objectives. It showed that for a specific design objective, higher recovery rate can be achieved by increasing the DS flowrate and number of elements in a pressure vessel. In contrast, lower final concentration can be obtained by lowering the DS flowrate and increasing the number of elements. Finally, a MATLAB based software with graphical user interface was developed to make the analysis process easier and efficient. Graphical abstract Image 1 Highlights • Full scale numerical simulation of FO process was investigated. • A novel optimization algorithm was developed by overall performance of the system. • Four elements was found to be optimum for 50% recovery rate. • MATLAB based graphical user interface was developed for efficient full scale FO system analysis. [ABSTRACT FROM AUTHOR]

In the present study a comprehensive thermodynamic model and degradation based optimization framework for energy management of anode supported solid oxide fuel cell (SOFC) stacks are carried out. The optimization framework determines optimum operating conditions to maximize system productivity (energy generation over system lifetime) considering degradation mechanisms. The main degradation mechanisms in anode supported SOFCs are nickel coarsening and oxidation. In this study, the optimum operating conditions regarding these degradation mechanisms to achieve maximum productivity at different target lifetimes are derived. The results show that target lifetime has a significant impact on system productivity and optimum operating temperature and current density. Furthermore, SOFC optimum operating conditions as a function of target lifetime are derived. To show the effectiveness of the developed framework, model outputs are compared with two other operating strategies; a base case strategy that optimizes system operating conditions without considering degradation mechanisms and a strategy based on Department of Energy’s (DOE) 2016 fuel cell report. Results illustrated that degradation based optimization is more beneficial for improving the entire performance in long-term operation. For instance, system productivity is 7.4% higher in comparison with DOE strategy during 40,000 h operating lifetime. It is expected that the proposed methodology will lead to more rapid commercialization of SOFC technology. [ABSTRACT FROM AUTHOR]

The performance of multistage air gap membrane distillation (MS-AGMD) system is experimentally investigated. The effects of feed temperature and flow rate, coolant temperature and flow rate, air gap width, and feed concentration on the system performance are studied. Parallel and series flow stage connections for the feed stream and coolant stream are tested. Energy analysis is performed for the MS-AGMD and compared with the single stage system. Parallel stage connection shows better performance than series connections in terms of permeate flux and energy consumption. The distillate volume of MS-AGMD module is measured to be 2.6 and 3 times the distillate volume of single stage AGMD module, for series and parallel stage connections; respectively. However, the specific energy consumption of multistage system is only 1.5 times the single stage system. The gain output ratio of the parallel stage MS-AGMD system is higher than the series stage MS-AGMD system, and it reached 0.6 for parallel MS-AGMD system and 0.45 for the series MS-AGMD system, at 90 °C. [ABSTRACT FROM AUTHOR]

This paper provides an energy consumption model and explains how the operating conditions and structural parameters of a crushing chamber affect energy consumption. Energy consumption is closely related to compressive pressure and displacement. The relationship between pressure, displacement and structural parameters is discussed. The influence of operating parameters on pressure and displacement based on the law of motion of material is examined. Energy consumption can be obtained by the product of pressure and displacement. In consideration of the pressure on the liner surface, which varies according to both height and circumference, an infinitesimal method was used to solve the issue of energy consumption. We validated the predicted energy consumption during breakage with experimental data from a PYGB1821 cone crusher which was consistent with the measured results. Finally, we provide an explanation of the influence of operating parameters and structural parameters on compressive pressure and displacement as well as energy consumption.

Depletion of fossil fuels has increased the pressure on energy systems to operate in the most efficient and economical mode. This tendency promotes energy systems to operate at optimum operating conditions, which maximizes the system profit over lifetime. Recently, there have been many attempts to maximize lifetime profit. Most of them concentrate on the power generation aspect without incorporating further aspects such as system degradation and profitability through lifetime. However, the main intention of the system operators is to optimize the profitability of system at the moment of operation and not the total profitability through the system lifetime. In this study a novel approach is developed which considers degradation mechanisms in optimization procedure. A DBO (degradation based optimization) framework maximizes system profit through its lifetime. The proposed framework can be applied to energy systems and the optimum operating conditions and replacement intervals can be determined. Solid oxide fuel cell is considered as the case study to validate the developed framework. The results show the value and effectiveness of DBO framework to improve the lifetime profit during system operation. Using DBO, the system lifetime profit for proposed case study is increased up to 10.45%. [ABSTRACT FROM AUTHOR]

A simulation model of a small-scale solid oxide iron–air battery system was developed to clarify its fundamental characteristics and feasibility from the view point of energy efficiency. The energy flow in one cycle of charge/discharge operations was evaluated under a quasi-state assumption with 0-dimensional models of the system components, i.e., a solid oxide electrochemical cell, an iron (Fe) box and heat exchangers. Special care was taken when considering thermal aspects; not only a simple system but also a more complicated system with thermal recirculation by three heat exchangers was investigated. It was found that the system round-trip efficiency reaches 61% under the base conditions in this study. The results also show that several limitations exist for the operation parameters and conditions in view of practical applications. In particular, higher and lower limits exist for the fuel and air utilization factors under which the system operates effectively because of constraints such as the maximum allowable fuel-blower temperature and no heat input during the discharge operation. [ABSTRACT FROM AUTHOR]

This work presents a systematic evaluation of the membrane and process characteristics of a scaled-up pressure retarded osmosis (PRO). In order to meet pre-defined membrane economic viability (≥ 5 W/m 2 ), different operating conditions and design parameters are studied with respect to the increase of the process scale, including the initial flow rates of the draw and feed solution, operating pressure, membrane permeability-selectivity, structural parameter, and the efficiency of the high-pressure pump (HP), energy recovery device (ERD) and hydro-turbine (HT). The numerical results indicate that the performance of the scaled-up PRO process is significantly dependent on the dimensionless flow rate. Furthermore, with the increase of the specific membrane scale, the accumulated solute leakage becomes important. The membrane to achieve the optimal performance moves to the low permeability in order to mitigate the reverse solute permeation. Additionally, the counter-current flow scheme is capable to increase the process performance with a higher permeable and less selectable membrane compared to the co-current flow scheme. Finally, the inefficiencies of the process components move the optimal APD occurring at a higher dimensionless flow rate to reduce the energy losses in the pressurization and at a higher specific membrane scale to increase energy generation. [ABSTRACT FROM AUTHOR]

The present paper aims at analysing the performances of organic Rankine cycles adopted for the exploitation of the biomass resulting from the pruning residues in a 3000 hectares district in Southern Italy. A parametric energy analysis has been carried out to define the influence of the main plant operating conditions. To this purpose, both subcritical and transcritical power plants have been examined and saturated and superheated conditions at the turbine inlet have been imposed. Moreover, the effect of the working fluid, condensation temperature, and internal regeneration on system performances has been investigated. The results show that the organic Rankine cycle plants represent an interesting and sustainable solution for decentralised and small-scale power production. Furthermore, the analysis highlights the significant impact of the maximum temperature and the noticeable effect of internal regeneration on the performances of the biomass power plants. [ABSTRACT FROM AUTHOR]

Supercritical water gasification (SCWG) of coal is a clean coal utilization technology that has gradually developed in recent years. It has great application prospect because of low pollution, good economy and high energy efficiency. Due to the complexity of coal molecular structure, it is difficult to directly study SCWG mechanism of coal at molecular level. Based on the Wiser molecular structure model of coal, diphenyl ether and diphenylmethane were selected as model compounds to study the bond breaking characteristics and gasification law of characteristic bridge bonds. The effects of catalyst, temperature, concentration and other factors on model compounds gasification were discussed. The results showed that temperature had the most significant influence on gasification effect. The effect order of catalyst on promoting gasification from high to low was: K 2 CO 3 > Na 2 CO 3 > Ca(OH) 2. The increase of catalyst amount and residence time had a certain promotion effect on gasification reaction. Under the same condition, the gasification effect of diphenyl ether was better than that of diphenylmethane. At the same time, the kinetic model of coal-like structure model compound gasification in SCW was established, and the key parameters were solved. The activation energy of diphenyl ether and diphenylmethane was 82.96 kJ/mol and 99.92 kJ/mol, respectively. [Display omitted] • The SCWG characteristics of coal-like model compounds are discussed. • Co-catalysis of K 2 CO 3 and Ca(OH) 2 increases the hydrogen yield by nearly 50%. • Temperature has the most significant effect on gasification effect. • The gasification kinetics of coal-like model compounds are studied. [ABSTRACT FROM AUTHOR]

Abstract: Fuel cells have unique technological attributes: efficiency, minimization of moving parts and low emissions. The Direct Methanol Fuel Cell (DMFC) has attracted much attention due to its potential applications as a power source for transportation and portable electronic devices. With the advance of micromachining technologies, miniaturization of power sources became one of the trends of evolution of research in this area. Based on the advantages of the scaling laws, miniaturization promises higher efficiency and performance of power generating devices, so, MicroDMFC is an emergent technology. There has been a growing interest in the development of this type of micro cells in the last years, resulting both in experimental studies (operating conditions, cell design and new materials) and in modeling studies. Despite the increase in the knowledge acquired, many challenges are still to be reached. This paper provides a detailed comprehensive review both on fundamental and technological aspects of micro-direct methanol fuel cells. Special attention is devoted to systematization of published results on experimental area since to date and also to a special section dedicated to modeling studies. [Copyright &y& Elsevier]

Abstract: CO2 emission from combustion flue gases has become the primary factor in global warming. Chemical methods of absorbing CO2 from combustion flue gases have been widely used in engineering, because of its simple and convenient operation, high absorption efficiency and economic value. This paper analyses the domestic and foreign researches on chemical methods of absorbing CO2 from combustion flue gases, and summaries the effect of the reactors structure, absorbent type and operating conditions on absorption efficiency. This article also forecasts present developmental directions, and expects to have a certain reference to later research and development. [Copyright &y& Elsevier]

Abstract: This paper was presented to determine the methanol crossover and efficiency of a direct methanol fuel cell (DMFC) under various operating conditions such as cell temperature, methanol concentration, methanol flow rate, cathode flow rate, and cathode backpressure. The methanol crossover measurements were performed by measuring crossover current density at an open circuit using humidified nitrogen instead of air at the cathode and applied voltage with a power supply. The membrane electrode assembly (MEA) with an active area of 5cm2 was composed of a Nafion 117 membrane, a Pt–Ru (4mg/cm2) anode catalyst, and a Pt (4mg/cm2) cathode catalyst. It was shown that methanol crossover increased by increasing cell temperature, methanol concentration, methanol flow rate, cathode flow rate and decreasing cathode backpressure. Also, it was revealed that the efficiency of the DMFC was closely related with methanol crossover, and significantly improved as the cell temperature and cathode backpressure increased and methanol concentration decreased. [Copyright &y& Elsevier]

With the deployment of battery electric buses (BEB) increasing worldwide, proper battery sizing becomes more critical for operators as it dictates bus driving range and costs. In this paper, we present a battery sizing framework based on comprehensive energy needs assessment for BEB. The bus operating conditions are first defined for different types of bus service (City, intercity, shuttle, regional, rapid-transit). Then, BEB energy consumption is evaluated using a comprehensive energy model developed by the authors. Finally, the required battery size is estimated for different types of charging infrastructure. Modeling results show that BEB energy consumption is sensitive to bus service type, ranging widely between 2 and 4.6 kWh/km, and that intercity buses require the largest battery size (320–680 kWh). A practical finding for operators from our Paris case study is that city bus batteries are unnecessarily oversized to accommodate a typically small fraction of trips in rare extreme cold weather conditions. • Study proposes a battery sizing framework for electric buses. • Evaluates energy consumption and battery sizing for different types of bus service. • Tool to estimate the required battery size and charging infrastructures. • Bus energy consumption and battery size are sensitive to its transit service type. • City bus Batteries oversized to accommodate small number of trips during the year. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) in urban China generally face operational difficulties. To comprehensively analyze the current operation status and determine the factors that caused difficulties in urban domestic WWTPs, we conducted a questionnaire survey, and 18 operating conditions of scale-level WWTPs in seven regions in China were investigated. The research results showed that, of the 467-urban domestic WWTPs surveyed in China, approximately 63.17% of the WWTPs' hydraulic loading rates (HLRs) are greater than 80%, 67.02% of the WWTPs have mixed liquor suspended solids (MLSS) concentrations greater than 4000 mg/L, and 95.93% of the WWTPs' mixed liquor volatile suspended solids to mixed liquor suspended solids (MLVSS/MLSS) ratios are lower than 0.7. The WWTP energy consumption accounts for approximately 1% of the national electricity consumption, and approximately 100,000 tons of various chemicals are consumed every year. A high HLR, a high activated sludge concentration and low sludge activity, design value mismatches with actual values, high energy and material consumption, etc. have become the main operational difficulties of urban domestic WWTPs. In this study, the main barriers that hinder improving the operating efficiency of WWTPs were investigated, the causes of operational dilemmas were analyzed, and pathways were jointly explored to solve them. This study may provide valuable implications for industry practitioners with a comprehensive grasp of the industry's current status and related policy formulation. • Current operation state of WWTPs in urban China was evaluated. • High HLR, Low MLVSS/MLSS, mismatch in design and actual, high energy consumption are main operation dilemmas. • Undeveloped sewers, inefficient treatment facilities, etc. were responsible for low efficiency of WWTPs. • The optimization of WWTP needs to start from the management of facilities and operation, establishment of supervision system. [ABSTRACT FROM AUTHOR]

Innovations in advanced materials in recent years have produced great improvements in the permeance of reverse osmosis (RO) membranes for desalination. This work presents a simplified techno-economic analysis for a representative advanced spacer and a high-permeance RO membrane under typical feed and operating conditions. The results agree with common trends for specific energy consumption (SEC). For high-permeance membranes, advanced spacers are more effective than conventional spacers in improving flux in the region close to the inlet, due to a fast decrease in Reynolds number along the channel. The total cost for seawater RO (SWRO) and brackish water RO (BWRO) could be reduced by 7.5% and 32%, respectively by increasing the membrane permeance to 10 L/m2.h.bar regardless of the spacer type used. However, as feed velocity has negligible effects on total cost for high-permeance membrane systems, further cost reductions with larger membrane permeances are limited due to significant concentration polarisation and lower mass transfer. Nevertheless, when operating SWRO at constant recovery, those levels of cost reduction can be achieved with an advanced spacer at half of that membrane permeance value. This highlights that more cost-effectiveness can be gained by improving the spacer efficacy than by increasing membrane permeance. • Case for using advanced spacers with high permeance RO membranes is presented. • Data from techno-economic analysis agrees with SEC reported in the literature. • Desalination cost reduction is limited at higher permeance due to high CP & low k mt. • Advanced spacers enable larger flux for high-permeance membranes toward the inlet. • Improving spacer design is more crucial than increasing permeance at same recovery. [ABSTRACT FROM AUTHOR]

• Real-time dynamic scenarios are investigated in the context of indoor environment. • The necessity of implementing CO 2 mass balance Equation has been established. • A demand-controlled ventilation (DCV) resetting strategy is proposed. • The proposed approach demonstrates significant energy savings potential. The ventilation component is one of the critical parts in an heating, ventilation and air-conditioning systems (HVAC) system and holds prime importance in ensuring operational efficacy and efficiency in terms of energy consumption and indoor environmental conditions. A true demand-based ventilation system with an economy air cycle not only offers reduced amounts of energy consumption but also can take part in a healthy indoor environment. This study provides true insight into the performance of a typical variable-air-volume air handling unit system under different operating conditions through a rigorous case study analysis in a real commercial building. To highlight pragmatic solutions to existing complexity within demand control ventilation strategies of the case building this study sets up real-time dynamic scenarios and investigates those scenarios in the context of indoor environment where both carbon dioxide (CO 2) and volatile organic compound (VOC) concentrations are linked. To predict and monitor the indoor air CO 2 concentration for the stated real time scenarios this study uses the mass balance equation for CO 2 concentration. This study demonstrates that integrating the CO 2 mass balance equation along with CO 2 sensor data into the building management control system not only assists in reducing energy consumption but also takes part in a healthy indoor environment. This study suggests including the mass balance equation for CO 2 concentration into the Australian ventilation standard AS 1668.2. [ABSTRACT FROM AUTHOR]

A large-scale seawater reverse osmosis (SWRO) plant was designed with a capacity of 10 million imperial gallon per day (MIGD) and to optimize design factors and operating conditions of the plant, various evaluations were undertaken. These involved pretreatment investigations, split partial simulations, evaluation of the final water quality with respect to production capacity, and a performance comparison with other SWRO plants using the normalized specific energy consumption (SEC). As a result, the turbidity and silt density index values of the pretreatment permeates were not affected by the productivity of the plant during the operation period. Additionally, the optimum split partial ratio of the RO membranes was determined to be 4.5:5.5 which satisfied the final produced water quality and energy consumption requirements. Based on the split partial ratio, the total dissolved solids (61–280 mg/L) and boron (0.1–0.9 mg/L) concentrations of the final permeate satisfied the Korean standards at all capacities (5.7, 8.0, 10 MIGD). In particular, the total SEC of the 10 MIGD train was estimated as 3.66 kWh/m3, which is greatly lower compared to that of other SWRO plants with similar capacities. Thus, these specific performance evaluations will be useful in determining the optimal design factors and operating conditions for other large-scale SWRO plants. Image 10571 • A large-scale seawater reverse osmosis (SWRO) plant was evaluated for desalination. • RO simulations, water qualities, and energy consumptions of the plant were compared. • Optimal design factors and operating conditions of the SWRO plant were determined. [ABSTRACT FROM AUTHOR]

Most purification systems work correctly from the point of view of water quality; purification, like any industrial process, must also be carried out efficiently with a minimization of costs. The overall project examined the potential benefits of using a recommended methodology for process evaluation and energy optimization in the aeration stage of activated sludge in the biological reactor at wastewater treatment plants (WWTP), which accounts for more than 44% of total operating costs. This energy control methodology encompasses the process, the installation and the control system. These three phases are examined in separate articles to make it easier to guide the user in the arduous task of optimizing energy efficiency of the WWTP from start to finish. This article focuses on Phase I of the methodology, the stage in charge of selecting the correct variables to control the best process conditions in the activated sludge system of the WWTP. Operating conditions that are a function of the recommended sludge age are influenced by exogenous factors such as temperature. The implementation of a real-time control system of the selected process variables, adapted to the needs, achieves reductions in the overall energy consumption of the installation, in this phase alone, of more than 15%, by reducing the oxygen requirements of the system and the recirculation ratios. [ABSTRACT FROM AUTHOR]

This paper provides an energy consumption model and explains how the operating conditions and structural parameters of a crushing chamber affect energy consumption. Energy consumption is closely related to compressive pressure and displacement. The relationship between pressure, displacement and structural parameters is discussed. The influence of operating parameters on pressure and displacement based on the law of motion of material is examined. Energy consumption can be obtained by the product of pressure and displacement. In consideration of the pressure on the liner surface, which varies according to both height and circumference, an infinitesimal method was used to solve the issue of energy consumption. We validated the predicted energy consumption during breakage with experimental data from a PYGB1821 cone crusher which was consistent with the measured results. Finally, we provide an explanation of the influence of operating parameters and structural parameters on compressive pressure and displacement as well as energy consumption. [ABSTRACT FROM AUTHOR]