The pumped two-phase cooling method is a practical way to dissipate heat from the battery module. The operating parameters of the cooling system should be investigated thoroughly to improve the performance of the battery thermal management system (BTMS). However, the previous BTMS designs only explored the thermal performance and ignored the electrical performance in the battery module. This study designed a pumped two-phase cooling BTMS with the refrigerant of R1233zd. An electrothermal coupled model was established for a series-connected battery module to predict thermal and electrical behavior. The results showed that the pumped two-phase cooling system could obtain excellent cooling performance with low system pressure under 2C discharging condition. The average temperature of the module and the temperature difference among cells could be maintained under 40 °C and 5 K under a 2C discharging rate. A lower saturation temperature, higher mass flux, and higher subcooling degree could... [more]

As the energy crisis intensifies, the global demand for natural gas is growing rapidly. Liquefied natural gas (LNG) technology is among the delivery solutions with flexible and reliable application prospects and is already a significant field of research in energy utilization. The performance of natural gas liquefaction process has a major influence on the production capacity, energy consumption, economics, and safety of the entire supply chain. Many scholars have conducted numerous studies on various LNG processes and designed many classical processes. This paper summarizes and discusses current research status and development level in the design and optimization of natural gas liquefaction processes in recent years, mainly focusing on cascade liquefaction process, expansion liquefaction process, and mixed refrigerant liquefaction process. The advantages and disadvantages of various liquefaction processes are compared and analyzed in terms of liquefaction capacity, energy consumption,... [more]

This paper proposes a novel T-type 7-level single-phase DC-AC inverter having a single input power source, self-balancing, and voltage gain of 3 along with low total harmonic distortion (THD). Since the structure of the proposed 7-level DC-AC inverter is symmetrical, the interchangeability of mass production can be easily achieved. In addition, because only one switch works for all time, the switch has quite low switching loss and voltage stress as well as the control being very easy. Furthermore, not only the proposed 7-level DC-AC inverter is analyzed in detail by the operating principle, but also the mathematical model for the adopted level-shift sinusoidal pulse width modulation (LS-SPWM) for this multilevel DC-AC inverter is successfully developed by using the well-known state averaging technique widely employed in the DC-DC converter. As a result, the required proportional-integral (PI) controller, used in the closed loop, can be designed systematically and easily. Eventually, th... [more]

The fuel cell is vital in electrical distribution networks as a distributed generation in today’s world. A precise model of a fuel cell is extensively required as it rigorously affects the simulation studies’ transient and dynamic analyses of the fuel cell. This appears in several microgrids and smart grid systems. This paper introduces a novel attempt to optimally determine all unknown factors of the polymer exchange membrane (PEM) fuel cell model using a meta-heuristic algorithm termed the Lightning search algorithm (LSA). In this model, the current−voltage relationship is heavily nonlinear, including several unknown factors because of the shortage of fuel cell data from the manufacturer’s side. This issue can be treated as an optimization problem, and LSA is applied to detect its ability to solve this problem accurately. The objective function is the sum of the squared error between the estimated output voltage and the measured output voltage of the fuel cell. The constraints of the... [more]

The aim of the present study was to investigate the effects of the application of hydrotreated vegetable oil (HVO) mixed with pure duck fat (F100) as fuel, replacing the conventional fossil diesel fuel (D100). The tests were performed using a four-stroke direct injection CI engine diesel engine. Six fuel samples were used: D100, HVO100, F100, as well as three HVO−fat mixtures F25, F50, and F75. To further study the main characteristics of fuel combustion, the AVL BOOST software (Burn program) was applied. The results of experimental studies showed that with the addition of pure fat to HVO, the ignition delay phase increased with an increase in the amount of heat released during the premix combustion phase and the pressure and temperature rise in the cylinder increased; however, the mentioned parameters were not higher as compared to diesel fuel. It was found that as the concentration of fat in the HVO−fat mixtures increases, the viscosity and density increases, while LHV was decreased,... [more]

Low salinity water injection (LSWI) is considered to be more cost-effective and has less environmental impacts over conventional chemical Enhanced Oil Recovery (EOR) methods. CO2 Water-Alternating-Gas (WAG) injection is also a leading EOR flooding process. The hybrid EOR method, CO2 low salinity (LS) WAG injection, which incorporates low salinity water into CO2 WAG injection, is potentially beneficial in terms of optimizing oil recovery and decreasing operational costs. Experimental and simulation studies reveal that CO2 LSWAG injection is influenced by CO2 solubility in brine, brine salinity and composition, rock composition, WAG parameters, and wettability. However, the mechanism for increased recovery using this hybrid method is still debatable and the conditions under which CO2 LSWAG injection is effective are still uncertain. Hence, a comprehensive review of the existing literature investigating LSWI and CO2 WAG injection, and laboratory and simulation studies of CO2 LSWAG injecti... [more]

In this study, an algae biomass gasification process using a dual fluidized bed with combined power and methanol cogeneration was developed. The gasification process was modeled using Aspen Plus and validated using experimental data of two microalgae species (Nannochloropsis oculata and Dunaliella salina) commonly found on the western coast of Saudi Arabia. The impacts of different operating conditions, including the gasifier temperature, steam-to-biomass ratio, and algae-char split ratio, on the compositions of four main gases (CO, CO2, CH4, and H2) were investigated. The results of the parametric studies indicated that the gasification temperature has a significant effect on the composition of the synthesis gas, where 700−850 °C was the ideal operating range for gasification. Altering the ratio of biomass to steam showed a slightly smaller effect on the synthesis gas composition. The char split ratio should be kept below 75% to ensure an adequate heat supply to the process. The propo... [more]

Carbonated water has proven advantages over conventional CO2 injection in terms of arresting free CO2 mobility, low-pressure injection, lower volume requirement, and higher efficiency. The term “engineered water” is designated to selective ion-spiked injection water with the advantage of the ion-exchange reactions with the rock minerals and releasing trapped oil. This article investigated the synergic effect of dissolved CO2 and engineered water for oil recovery and understanding inner mechanisms. Recovery efficiencies were evaluated through coreflood studies, which revealed that the hybrid water could recover 6−10% more oil than engineered water and about 3% more than carbonated water. HP-HT pendant-drop studies show the insignificance of IFT reduction. Wettability change from oil wet to near-water wet is attributed as a significant factor. The dissolution of Ca2+ and Mg2+ and deposition of SO42− observed in coreflooding may have a significant contribution to oil recovery. Pore enlarg... [more]

This paper presents the high contact resistance (HCR) and rotor bar faults by an extraction method for an induction motor using Discrete Wavelet Transform (DWT) and Artificial Neural Network (ANN). The root mean square (RMS) and mean features are obtained using DWT, and ANN is used for classification using activation functions. Activation provides output by assigning the specific input with respect to the transfer function according to the nature and type of the activation function. Method: The faulty conditions are induced using MATLAB by adopting the motor current signature analysis (MCSA) method to achieve current signature signals of the healthy and faulty motors. Results: The DWT technique has been applied to obtain fault-specific features of the average continuously varying signal (RMS) and an average of the data points (mean) at levels 5, 7, 8, and 9, followed by ANN to classify the faults for condition monitoring. Utility: The utility of the results is to reduce unscheduled dow... [more]

One of the primary difficulties we have recently is environmental degradation. The deterioration of the environment was visible in the rise in carbon dioxide emissions, which has a detrimental impact on various life matters. A variety of factors caused this growth. Inappropriate human behaviors caused the majority of them. This study aimed to ascertain how energy consumption and economic growth with its components in the Czech Republic, affected CO2 emissions. The relationship between CO2 emissions, economic growth, agriculture, and energy consumption was studied using econometric analysis, specifically the Johansen, Vector Error Correction (VEC) Model, and granger causality. The findings revealed that all variables are cointegrated. Economic growth, agricultural, and energy consumption output are all positively correlated with CO2 emissions. There is a unidirectional Granger Causality between economic growth, and Agriculture towards carbon dioxide emissions. A unidirectional Granger C... [more]

Emissions from the road transport sector are a major contributor to the climate change. Commonly used heavy vehicles powered by diesel engines emit toxic and harmful compounds that adversely affect the environment. For this reason, increasingly newer Euro emission standards are being introduced. Therefore, the emission performance of heavy-duty vehicles used in the transportation processes of diverse loads was investigated. The first research object was a set of vehicles equipped with a crane used for loading and unloading timber. The measurements were carried out in a specially designed research test reflecting the way the vehicle is used. It consisted of the drive to the loading site, the transport of timber to the destination and the processes of loading and unloading timber. The test route included driving on both unpaved forest roads and asphalt roads. The second research object was a set of vehicles used in long-distance road transport. The research route characterizing the traff... [more]

Half Heusler materials are promising thermoelectric materials with potential application in generators at medium range temperatures. Solid solutions are typically prepared by arc melting, presenting interesting properties. In this work, the effect of Hf incorporation and the formation of solid solutions is discussed. More specifically, Ti1−xHfxNiSn and (Ti0.4Zr0.6)1−yHfyNiSn half Heusler materials were synthesized via mechanical alloying and consolidated via hot press sintering. Hf incorportation in the lattice strongly affected the lattice thermal conductivity due to the large mass fluctuation. The power factor and thermoelectric figure of merit was optimized via Sb doping the values of 34 μW/cmK2 and 38 μW/cmK2; 0.72 and 0.76 at 762 K for Ti0.4Hf0.6NiSn0.985Sb0.015 and (Ti0.4Zr0.6)0.7Hf0.3NiSn0.98Sb0.02, respectively, were reached.

The large-scale numerical simulation of complex flows has been an important research area in scientific and engineering computing. The lattice Boltzmann method (LBM) as a mesoscopic method for solving flow field problems has become a relatively new research direction in computational fluid dynamics. The multi-layer grid-refinement strategy deals with different-level of computing complexity through multi-scale grids, which can be used to solve the complex flow field of the non-uniform grid LBM without destroying the parallelism of the standard LBM. It also avoids the inefficiencies and waste of computational resources associated with standard LBMs using uniform and homogeneous Cartesian grids. This paper proposed a multi-layer grid-refinement strategy for LBM and implemented the corresponding parallel algorithm with load balancing. Taking a parallel scheme for two-dimensional non-uniform meshes as an example, this method presented the implementation details of the proposed parallel algo... [more]

Distribution network planners are facing a strong shift in the way they plan and analyze the network. With their intermittent nature, the introduction of distributed energy resources (DER) calls for yearly or at least seasonal analysis, which is in contrast to the current practice of analyzing only the highest demand point of the year. It requires not only a large number of simulations but long-term simulations as well. These simulations require significant computational and human resources that not all utilities have available. This article proposes a nonlinear clustering methodology to find a handful of representative medium voltage (MV) distribution feeders for DER penetration studies. It is shown that the proposed methodology is capable of uncovering nonlinear relations between features, resulting in more consistent clusters. Obtained results are compared to the most common linear clustering algorithms.

In low-latitude areas less than 10° in latitude angle, the solar radiation that goes into the solar still increases as the cover slope approaches the latitude angle. However, the amount of water that is condensed and then falls toward the solar-still basin is also increased in this case. Consequently, the solar yield still is significantly decreased, and the accuracy of the prediction method is affected. This reduction in the yield and the accuracy of the prediction method is inversely proportional to the time in which the condensed water stays on the inner side of the condensing cover without collection because more drops will fall down into the basin of the solar-still. Different numbers of scraper motions per hour (NSM), that is, 1, 2, 3, 4, 5, 6, and 7, are implemented to increase the hourly yield of solar still (HYSS) of the double-slope solar still hybrid with rubber scrapers (DSSSHS) in areas at low latitudes and develop an accurate model for forecasting the HYSS. The proposed m... [more]

With the rapid development of smart grids, the number of various types of power IoT terminal devices has grown by leaps and bounds. An attack on either of the difficult-to-protect end devices or any node in a large and complex network can put the grid at risk. The traffic generated by Distributed Denial of Service (DDoS) attacks is characterised by short bursts of time, making it difficult to apply existing centralised detection methods that rely on manual setting of attack characteristics to changing attack scenarios. In this paper, a DDoS attack detection model based on Bidirectional Long Short-Term Memory (BiLSTM) is proposed by constructing an edge detection framework, which achieves bi-directional contextual information extraction of the network environment using the BiLSTM network and automatically learns the temporal characteristics of the attack traffic in the original data traffic. This paper takes the DDoS attack in the power Internet of Things as the research object. Simulat... [more]

The limited availability of fossil fuels such as coal and increasing air pollution levels due to the burning of coal have pushed the trend of generating electricity from fossil fuels to generating it from locally available renewable resources. It is expected that the cost of electricity will decrease when locally available renewable resources are used. In this paper, it was proposed to commission a solar PV system in a part of an academic building of SRM IST University. The present study is an effort in-line with many initiatives taken up by the Indian Government. The performance index of solar PV system was analyzed. Supporting data were obtained from the NASA PDAV tool and then techno-economical analysis was carried out on HOMER. The average performance ratio and capacity factor of the solar PV system were obtained as 64.49% and 14.90%, respectively. For the optimal configuration, the net present cost and the levelized cost of electricity are $639,981 and $0.34 per kWh, respectively.... [more]

This paper proposes a buffered microgrid with a modular grid interface consisting of a modular back-to-back converter. The proposed method provides a flexible strategy that enables both the load and generation expansion of the microgrid, with no sizing constraints on the initial stage. The method maintains the physical separation of the buffered microgrid from the grid by using back-to-back converters, which ensures a safe, secure and seamless operation in both islanded and grid-connected operation modes. The proposed modular structure allows an energy exchange prioritization either between the energy storage systems and the grid or between the energy storage units themselves, depending on the recommended/desired operational strategy. The prioritizations are achieved by using sets of dead zones in the control of the interfacing converters. In order to control the voltage and frequency, an inverse-droop-based dq-frame current control method was implemented in PSCAD/EMTDC to substantiate... [more]

Biodiesel is a clean-burning, alternative diesel replacement fuel that may be used in existing diesel engines in either pure or blended form without or with modest modifications. In some countries, biodiesel is recommended as a potential alternative to diesel fuel since it is a renewable energy source that is environmentally benign. The main problems with the widespread commercialization of biodiesel are its high viscosity and its limited feedstock, due to which complete replacement of diesel fuel is not possible and the use of blends of biodiesel and petrodiesel are being used increasingly worldwide. The paper presents a behavioral study of the petro-based diesel, and their blend (B20, B40, B60, B80) with Pongamia and Jatropha biodiesel. The results reveal a considerable viscosity lowering due to the dilution effect of increasing diesel concentration in both the cases. In addition, improvements in oxidation stability in both cases have also been observed. The research shows that as th... [more]

This paper analyzes the digital signal processing techniques and estimates induction motor (IM) rotational speed operating in stationary or non-stationary conditions. Rotor slot harmonics present in the stator current waveform are used to estimate the induction motor speed with a given or identified rotor slot numbers. This paper’s contribution is the following: First, zoom improved short-time Chirp-Z transform is used to find supply frequency and the rotor slot harmonic frequency to improve the estimation accuracy without increasing computing complexity. Second, a technique is described that can be used to determine whether or not a motor can generate principal slot harmonics (PSH). Finally, an algorithm is designed to figure out the perfect window length and estimate the motors’ speed. This proposed technique was investigated when the motor was fed by an inverter-fed supply driving a variable load and operating in non-stationary conditions. Experimental test results on 5.5 kW and 22... [more]

The deep integration of power grids and communication networks is the basis for realizing the complete observability and controllability of power grids. The communication node or link is always built according to the physical nodes. This step is alternatively known as “designing with the same power tower”. However, the communication networks do not form a “one-to-one correspondence” relationship with the power physical network. The existing theory cannot be applied to guide the practical power grid planning. In this paper, a local evolution model of a communication network based on the physical power grid topology is proposed in terms of reconnection probabilities. Firstly, the construction and upgrading of information nodes and links are modeled by the reconnection probabilities. Then, the power flow entropy is employed to identify whether the power cyber-physical system (CPS) is at the self-organized state, indicating the high probability of cascading failures. In addition, on the ba... [more]

The development of solid oxide fuel cells (SOFCs) for powering vehicles requires high power densities. The radial flows generated by the insert structures in SOFC fuel channels could improve the power density by facilitating the fuel to enter the porous anode for electrochemical reactions. In this paper, we developed a 2D axisymmetric numerical model to examine the influence of a convergent conical ring insert on the flow and mass transfer characteristics in a tubular SOFC. The mass transfer conductance of fuel was analyzed and proposed to quantify the performance of different insert designs. The effects of the radius and offset angle of the convergent conical ring insert were examined and analyzed. We demonstrate that increasing the insert radius could increase the fuel mass transfer conductance and effectively improve the net output power of the tubular SOFC by 12% while the offset angle of the inserts exhibits a negligible impact on the fuel mass transfer conductance. Increasing the... [more]

In this paper, we present an approach for multi-level parallel-in-time (PinT) electromagnetic transient (EMT) simulation. We evaluate the approach in the context of power electronics system-level simulation. While PinT approaches to power electronics simulations based on two-level algorithms have been thoroughly explored in the past, multi-level PinT approaches have not yet been investigated. We use the multigrid-reduction-in-time (MGRIT) method to parallelize a dedicated EMT simulation tool which is capable of switching between different converter models as it operates. The presented approach yields a time-parallel speed-up of up to 10 times compared to the sequential-in-time implementation. We also show that special care has to be taken to synchronize the time grids with the electronic components’ switching periods, indicating that further research into the usage of different models from adequate model hierarchies is necessary.

This study comprehensively examines the effects of the COVID-19 pandemic on energy consumption in the United States. The purpose of the study is to quantify the effects of lockdowns and pandemic disruptions on energy consumption trends in order to inform policymakers and utilities on how to prepare for such events in the future. The study focuses on 2020 data collected by the Federal government. The effects are quantified using descriptive statistics. State-wise and sector-wise data have been presented using plots and heat maps. Related metrics like COVID case data, GDP, emissions, and expenditures were also presented. The total energy consumption fell by 7.5% in 2020. Besides Alaska, every state saw a decrease in energy, with some as high as 26%. The residential sector had the most states that saw an increase in energy, stemming from lockdowns and working from home. Similarly, petroleum consumption saw a decrease of 11.4% as a result of a decrease in travel. Biomass-related renewable... [more]

This study aims to evaluate the trade-off between using cheaper and contaminated energy versus cleaner and more expensive energy and ultimately assess their combined effect on social externalities. We estimate the impact of air pollution and income level—mechanisms of energy consumption—on violent crimes and mortality rates. We propose an integrated causal analysis to address an endogeneity concern caused by the energy selection process by employing a difference-in-differences method (DiD) for the mechanism approach using policy changes. We explore the energy variations in neighboring counties caused by the implementation of green act policies to measure violent crimes and mortality rates using air pollution and income as the mechanisms. The results reveal that reducing fossil fuel by one terawatt hour can save 23 lives. Further, lowering nonrenewable energy use reduces 53 rapes yearly by lowering the maximum temperature, whereas decreasing fossil fuel does not negatively impact produc... [more]