Isolated ultrasonic vibrations were used to treat feed water from a 20 bar steam-producing water tube boiler. Physical treatments such as ultrasounds and reverse osmosis (RO) are recommended as the most eco-friendly for this purpose. A novel bench-scale prototype delivering 6 L/h of treated water was designed and built. The ultrasonic atomization of raw water with 1.7 MHz piezoelectric transducers and subsequent humidification and dehumidification of drag airflow was the innovating sequence of operations used as a treatment technique. To ensure greater humidification capacity to the drag air, the energy available from the thermal inertia of the liquid column (raw water) in the prototype vaporization chamber was used to heat this air flow. After a single pass of raw water through the bench-scale prototype, a 98.0% reduction in conductivity and a 99.0% decrease in the content of total dissolved solids were obtained at a drag air temperature of 70 °C. Compared to RO, two of the main advan... [more]

In the U.S., approximately 47% of the total electricity use comes from residential buildings. Most of the residential buildings use HVAC system to ventilate, cool, or heat the indoor environmental spaces mechanically, rather than using natural outdoor air in transition seasons, even though the outdoor environmental conditions are favorable for indoor thermal comfort. In this case, an HVAC system using mixed-mode ventilation with an appropriate ratio of using indoor air and outdoor air could decrease the energy use in residential buildings. This research uses high-granular HVAC electricity use data with indoor thermostat data and outdoor weather data from residential buildings in Austin, Texas, to evaluate the benefits of energy and economics when using HVAC mixed-mode ventilation in spring and fall transition seasons. The results demonstrate that the household owners could save approximately 150.79 kWh of total HVAC energy use and 24.41% of HVAC cost in spring transition months (April/... [more]

In recent years, machine learning, especially deep learning, has developed rapidly and has shown remarkable performance in many tasks of the smart grid field. The representation ability of machine learning algorithms is greatly improved, but with the increase of model complexity, the interpretability of machine learning algorithms is worse. The smart grid is a critical infrastructure area, so machine learning models involving it must be interpretable in order to increase user trust and improve system reliability. Unfortunately, the black-box nature of most machine learning models remains unresolved, and many decisions of intelligent systems still lack explanation. In this paper, we elaborate on the definition, motivations, properties, and classification of interpretability. In addition, we review the relevant literature addressing interpretability for smart grid applications. Finally, we discuss the future research directions of interpretable machine learning in the smart grid.

For commercial buildings, liquid desiccant air conditioners (LDACs) could provide up to 80% energy savings compared to high-efficiency vapor compression AC, but commonly utilized liquid desiccants are highly corrosive. This precludes the use of metallic components, necessitating specialized plastics and thereby driving up cost, weight, and limiting operational temperature and pressure ranges. Less corrosive alternatives are sought. Here, potassium acetate solutions are investigated as less-corrosive alternatives to the chloride salt solutions that are typically used in LDAC systems. Corrosion evaluations for a Cu alloy (C12200) and two Al alloys (Al3003 and Al1100) in both potassium acetate and chloride salt solutions are presented. We show that yearly corrosion rates are lower in potassium acetate solutions by up to three orders of magnitude. Active corrosion behavior is largely absent in potassium acetate solutions but is present in chloride salt solutions. Furthermore, solid corrosi... [more]

The stringent regulations set by the International Maritime Organization on pollutant emissions combined with the rise in fuel prices have stimulated research on cleaner fuels and new propulsion systems. This study describes a new method for evaluating alternative technologies and cleaner fuels that can be utilised in the marine sector to replace heavy fuel oil and diesel engines, and thus improve their performance while lowering carbon dioxide and nitrogen oxide emissions. The proposed techno-environmental technique allows consistent evaluation of simple intercooler/reheat gas and steam combined cycles fuelled by marine diesel fuel and liquefied natural gas, instead of a two-stroke diesel engine fuelled by marine diesel fuel, as a propulsion system of a large container ship. The implementation of the enhanced combined gas and steam cycles, and combined gas and steam cycles, fuelled by liquefied natural gas, increases the engine’s efficiency by 11% as compared with that of two-stroke d... [more]

The notion of thermophoretic particle deposition is used in a number of applications, including thermal exchanger walls. It is important to identify the transport processes in action in systems such as thermal precipitators, exhaust devices, optical transmission fabrication processes, and so on. Based on these application points of view, the present work studies the performance of nanoparticle aggregation stagnation point flow over a rotating sphere during the occurrence of thermophoretic particle deposition. The nonlinear governing equations are transformed into the ordinary differential equation by utilizing suitable similarity variables. The numerical outcomes of the reduced equations along with boundary conditions are solved by the Runge−Kutta−Fehlberg 45 (RKF-45) order method with shooting procedure. The numerical results are shown with the assistance of graphs. The impacts of various dimensionless constraints on velocity, thermal, and concentration profiles are studied under the... [more]

As a vital market mechanism to mitigate global warming, the emissions trading system (ETS) has critical research and practice value. According to articles from Web of Science’s core collection, quantitative statistics are used to analyze the ETS, including statistics on the number of articles, distributions of time and geography, journals and subjects, productive authors and institutions, academic collation, article citations, and hot topics. Moreover, this paper presents a qualitative analysis of research on the ETS, exploring hot issues, including its origin, allowance allocation, the impact of allowance allocation, and the ETS in the power sector. The results show that it is necessary to launch ETS to mitigate climate change effectively and reduce emissions at a low cost. Allowance allocation as its critical component has also caused heated discussion among scholars. In allowance allocation, exploring a desire to assign the future allowable carbon emissions reasonably and efficientl... [more]

A design methodology for minimum volume of LCL filters applied to grid connected converters is proposed. It combines the determination of filter parameter values (inductances and capacitances) to hardware design (component technology and inductor construction). Using the proposed strategy, different combinations of L-C-L that meet standard restrictions are determined. The influence of the harmonic content that results from filter design is considered in order to estimate component losses, and filter and bus capacitor lifetimes. Results are presented for filters that lead to the smallest volume, highest capacitor lifetime, or a compromise between both. A case study with three different magnetic material technologies and two types of capacitors is done. The design methodology is experimentally validated for a 1 kW converter. Step-by-step procedures for the determination of filter parameters and inductor hardware design are provided.

Underground coal gasification (UCG) can be considered as one of the clean coal technologies. During the process, the gas of industrial value is produced, which can be used to produce heat and electricity, liquid fuels or can replace natural gas in chemistry. However, UCG does carry some environmental risks, mainly related to potential negative impacts on surface and groundwater. Wastewater and sludge from UCG contain significant amounts of aliphatic and aromatic hydrocarbons, phenols, ammonia, cyanides and hazardous metals such as arsenic. This complicated matrix containing high concentrations of hazardous pollutants is similar to wastewater from the coke industry and, similarly to them, requires complex mechanical, chemical and biological treatment. The focus of the review is to explain how the wetlands systems, described as one of bioremediation methods, work and whether these systems are suitable for removing organic and inorganic contaminants from heavily contaminated industrial wa... [more]

The Medium Voltage DC (MVDC) architecture for All Electric Ships (AES) has the potential to provide superior features compared to traditional 60-HZ AC distribution systems in terms of power density, power quality, and system stability. The MVDC system introduces extensive use of power electronics equipment into the shipboard power system (SPS) design that brings complexity to the system design. These power electronics equipment connect the power sources and load centers to the MVDC bus and play a major role in handling system faults. This paper focuses on developing a framework to determine the volume and failure rate of a Modular Multilevel Converter (MMC) for early stage ship design. Two different methodologies (Taguchi method and a genetic algorithm) were used to determine the best design from a robust set of design options. Once the design parameters have been identified, the Taguchi method forms orthogonal array to explore and evaluate designs. At the end of the design cycle, it i... [more]

The present work mainly developed a mathematical model based on the plug flow model and coarse fly ash particles’ fragmentation model to describe the behavior and evolution of ash formation and the influence of the biomass feeding rate and flue gas cooling rate on ash properties, which is validated by literature data. The model considers homogeneous nucleation of alkali vapors, heterogeneous condensation of vapors on newly formed particles and fly ash particles, and collision-coagulation between aerosol particles, which is also applied to numerically study and analyze the ash formation characteristics in the cases of practical boiler pulverized fuel combustion and SO2 sulfation. The results show that the mathematical model can reasonably describe the ash formation and the influence of the biomass feeding rate and the flue gas cooling rate on the mass PSDs of PM10 and its elements. The initial nucleation temperature and initial nucleation particle size increase with the biomass feeding... [more]

Background: Specialist literature indicates a large share of the human factor among the causes of failure of technical systems at the level of 70 to 90%, which depends on the sector studied. The collective water supply system is an anthropotechnical system, i.e., it is a complex connection between man and the technical system resulting from the deliberate influence of man on the technical system. Methods: The work presents an assessment of operator reliability of a selected water treatment process based on the fault tree analysis (FTA). Elementary events are determined by the operator’s error probability. Results: A failure tree was prepared for the peak event of the filter station failure, resulting from an operator’s error during the filter washing procedure. The probability of a peak event occurring is 0.0580. Conclusions: The developed fault tree allows for the identification of elementary events leading to an emergency event. The operator fulfills its task of maintaining the conti... [more]

The present study investigates the effects of upstream ramps on a backward-injection film cooling over a flat surface. Two ramp structures, referred to as a straight-wedge-shaped ramp (SWR) and sand-dune-shaped ramp (SDR), are considered under a series of blowing ratios ranging from M = 0.5 to M = 1.5. Regarding the backward injection, the key mechanism of upstream ramps on film cooling enhancement is suggested to be the enlargement of the horizontal scale of the separate wake vortices and the reduction of their normal dimension. When compared to the SDR, the SWR modifies the backward coolant injection well, such that a larger volume of coolant is suctioned and concentrated in the near-field region at the film-hole trailing edge. As a consequence, the SWR demonstrates a more pronounced enhancement in film cooling than the SDR in the backward-injection process, which is the opposite of the result for the forward-injection scheme. For the SWR, the backward injection provides a better fil... [more]

Anaerobic digestion of animal manure is a potential bioenergy resource that avoids greenhouse gas emissions. However, the conventional approach is to use continuously stirred tank reactors (CSTRs) with hydraulic retention times (HRTs) of greater than 30 d. Reactors with biomass retention were investigated in this study in order to increase the efficiency of the digestion process. Filtered pig slurry was used as a substrate in an expanded granular sludge bed (EGSB) reactor and fixed-bed (FB) reactor. The highest degradation efficiency (ηCOD) and methane yield (MY) relative to the chemical oxygen demand (COD) were observed at the minimum loading rates, with MY = 262 L/kgCOD and ηCOD = 73% for the FB reactor and MY = 292 L/kgCOD and ηCOD = 76% for the EGSB reactor. The highest daily methane production rate (MPR) was observed at the maximum loading rate, with MPR = 3.00 m3/m3/d at HRT = 2 d for the FB reactor and MPR = 2.16 m3/m3/d at HRT = 3 d for the EGSB reactor. For both reactors, a re... [more]

The urgent need to meet climate goals provides unique opportunities to promote small-scale farm anaerobic digesters that valorize on-site wastes for producing renewable electricity and heat, thereby cushioning agribusinesses against energy perturbations. This study explored the economic viability of mono-digestion of cow manure (CWM) and piglet manure (PM) in small manured-based 99 kWel plants using three treatment schemes (TS): (1) typical agricultural biogas plant, (2) a single-stage expanded granular sludge bed (EGSB) reactor, and (3) a multistage EGSB with a continuous stirred tank reactor. The economic evaluation attempted to take advantage of the financial incentives provided by The Renewable Energy Sources Act in Germany. To evaluate these systems, batch tests on raw and solid substrate fractions were conducted. For the liquid fraction, data of continuous tests obtained in a laboratory was employed. The economical evaluation was based on the dynamic indicators of net present val... [more]

Space charge accumulation in polypropylene (PP) affect the dielectric properties and breakdown strength of the material. The pre-injected charge in PP under the action of different polarity voltage is quantitatively characterized, and the effects of the pre-injected charge inside the dielectric on the dielectric properties and breakdown strength are measured and analyzed. Based on the molecular simulations, the influence mechanism of the temperature on dielectric properties and breakdown are discussed. The experimental results show that the injected charges in PP under the negative polarity voltage is significantly larger than that of the positive polarity. These charges have a great influence on the dielectric constant and breakdown performance of PP, and the effect is different for different charge polarity. The effect of negative polarity pre-voltage conditions on the dielectric constant is much greater than that of positive polarity, and the dielectric constant of PP decreases from... [more]

In the north of China, during winter, a large number of activities (such as leisure, work, sightseeing and sports) are engaged in. This paper mainly focuses on human thermal perceptions of outdoor activities in a winter climate, especially the change in thermal perceptions when humans enter a temporary rest space with a shelter effect. A climate chamber was applied in our experiments, and temperature up-steps of 4, 8 and 12 °C were set, respectively. Twenty four college students were invited to engage in activities of different intensities, such as standing, walking (slowly) and biking. Through questionnaire survey and field measurement, the subjects’ thermal sensation, thermal comfort and skin temperature were obtained. Hypothesis testing and non-linear regression methods were introduced to analyze experiment data. Major results were as follows. After temperature up-step changes, thermal sensation and skin temperature reach steady state within 30 min. However, the change in skin tempe... [more]

The RF-driven negative ion source has a steady state characteristic and will be a promising ion source for neutral beam injection (NBI) in the future. Cesium (Cs) injection is an efficient method to enhance the yield of negative ions during plasma discharge. In order to support the engineering and physical research in this field, the Cs oven prototype has been developed for negative ion source based neutral beam injector at ASIPP. This article presents the design details of a Cs oven system, including the constant temperature control system, the mechanical structure of Cs oven, and the surface ionization detector (SID). SID is a measurement method for the cesium flux in the nozzle. The experiment results of constant temperature control system show that the control accuracy and function meet the requirements of device operation. Meanwhile, the simulation analysis of Cs vapor concentration has been carried out in this paper. According to the simulation results, the graph of total Cs flux... [more]

The water−energy nexus has become a key factor in the implementation of low-carbon green development, which has led to the need for exploring effective management within the coupled integrated system with multi-energy flow supplies. In this study, the coupled relationship between water resources and energy in the integrated energy system was systematically analyzed, and a system operation optimization model was proposed through comprehensively considering cold, heat and electricity load, and nine kinds of energy conversion and supply equipment/technology from the perspective of a water resources and energy nexus in a typical industry park. The system operation scheme, energy supply mode, net benefit and water resource consumption under different water resource control scenarios were obtained. The results show that water resource control would directly bring about a directly positive influence on renewable energy utilization and energy storage reduction, and that a system’s external dep... [more]

The decreasing cost of renewable energy resources and the developments in storage system technologies over recent years have increased the penetration of photovoltaic systems to face the high rise in the electricity load. Likewise, there has also been an increase in the demand for tools that make this integration process in the current power systems profitable. This paper proposes a mathematical model based on the DC optimal power flow equations to find the optimal capacity of the PV panels and batteries for a standalone system or a system supported by the grid, while the investment and the energy required by the grid are minimized. In this regard, five different locations have been used as case studies to measure the influence of the irradiance level on the PV-Battery capacity installed and on the economic indicators such as CAPEX, OPEX, NPV, IRR, and the payback period. Thus, a modified 14-bus system has been used to replicate the grid technical limitations and show that a PV-Battery... [more]

Three-phase motors are commonly adopted in several industrial contexts and their failures can result in costly downtime causing undesired service outages; therefore, motor diagnostics is an issue that assumes great importance. To prevent their failures and face the considered service outages in a timely manner, a non-invasive method to identify electrical and mechanical faults in three-phase asynchronous electric motors is proposed in the paper. In particular, a measurement strategy along with a machine learning algorithm based on an artificial neural network is exploited to properly classify failures. In particular, digitized current samples of each motor phase are first processed by means of FFT and PSD in order to estimate the associated spectrum. Suitable features (in terms of frequency and amplitude of the spectral components) are then singled out to either train or feed a neural network acting as a classifier. The method is preliminarily validated on a set of 28 electric motors,... [more]

Under the background of renewable-dominated electric power system construction, the penetration rate of low-carbon and renewable distributed generation (DG) in distribution network is increasing, which has changed the form and operation mode of the distribution network. To deal with the output fluctuation of high penetration DG in the distribution network operations, it is necessary to evaluate the acceptance capacity of DG. The correct evaluation can realize the secure, economic and low-carbon configuration of DG. In this paper, an evaluation method of acceptance capacity of DG in the distribution network considering the carbon emission is proposed. Firstly, a multi-objective evaluation model of acceptance capacity of DG is constructed with the objectives of minimizing carbon emission in the full life cycle, minimizing node voltage deviation and maximizing line capacity margin. Secondly, the improved non-dominated sorting genetic algorithm II (NSGA-II) is employed to solve the model t... [more]

Decarbonizing heating in buildings is a key part of climate change mitigation policies, but deep retrofit is progressing slowly, e.g., at a pace of 0.2%/y of the building stock in Europe. By means of tests in two flats of a multiapartment housing complex recently renovated to very low values of energy needs, this paper explores the role of deep retrofitted buildings in providing energy flexibility services for the occupants/owners/managers and for the energy system. Key to this flexibility increase and capacity savings is the large reduction of energy needs for heating via a high level of external insulation, which allows the thermal capacity of the building mass to act as an energy storage, without the large energy losses presently affecting a large part of the building stock. Due to the limited number of case studies reporting experimental applications in real buildings, this research aims to offer an analysis based on a series of tests and detailed monitoring which show a significan... [more]

The detonation properties of nonideal explosives are highly dependent on charge diameter and existence and properties of confinement. In this study, the effect of different confinements on the detonation velocity of ANFO explosives was experimentally determined along with the results of the plate dent test. ANFO explosive was selected as one of the most commonly used nonideal explosives. Following the measurement results, we found that the detonation velocity increased with increasing wall thickness, and the velocity increase was different for different confinement materials. A strong correlation existed between the ratio of the mass of confiner and explosive (M/C) and the detonation velocity (R = 0.995), and between (M/C) and the depth of the dent (δ) (R = 0.975). The data presented in this paper represent preliminary findings in developing a confinement model required for reliable numerical modeling of nonideal explosives.

Poor heat dissipation and thermal runaway are most common in batteries subjected to fast charge or discharge and forced to work in hot or subzero ambient temperatures. For the safe operation of lithium-ion batteries throughout their lifecycle, a reliable battery thermal management system (BTMS) is required. A novel hybrid BTMS with a nickel-titanium (NiTi) shape memory alloy (SMA) actuated smart wire and phase change material (PCM) with expanded graphite (EG) is proposed in this study. A lumped electrochemical-thermal battery model is developed to analyze the efficiency of the proposed hybrid BTMS. The multiphysics BTMS is investigated by discharging at various electrical currents in both off-modes (inactivated SMA) and on-modes (activated SMA). Under on-mode BTMS operation, temperature elevation is reduced by 4.63 °C and 6.102 °C during 3 C and 5 C discharge, respectively. The proposed hybrid BTMS can be considered a competitive alternative for use in electrical vehicles due to its sm... [more]