The lithium-ion battery (LIB) is widely used as an energy storage device for electric vehicles (EV) due to its advantages, such as high energy density and long lifespan. However, LIB for EV can be exposed to mechanical abuse such as vehicle collision, which causes thermal runaway due to extreme mechanical deformation. Therefore, it is necessary to predict the internal short circuit (ISC) of the LIB cell under mechanical loading conditions and to analyze the mechanical, electrical, and thermal responses after ISC. In this paper, the starting point of ISC is predicted using a two-way mechanical-electrical-thermal coupled analysis method. At the same time, mechanical responses, along with the effects of the ISC area on electrical and thermal responses of the LIB cell, were analyzed. ISC was defined as failure of the separator. The separator’s failure was calculated considering material nonlinearity. Considering the indentation test results, the finite element method (FEM) analysis could a... [more]

The present paper indicates that hydropower, including small hydropower plants (SHPs), may play a very important role in Poland’s energy transformation in the near future. The development of SHPs may also increase water resources in the steppe Poland. Additionally, the aim of the present research is to conduct the PEST analysis of SHPs in Poland, taking into account the SHP potential. For the first time, maps showing the power and location of potential SHPs on the existing dams in Poland are presented. SHPs should be an important element of energy transition in Poland, especially on a local scale—it is stable energy production. Our analysis shows that there are 16,185 such dams in Poland, while the total capacity of potential hydropower plants in Poland would be 523.6 MW, and the total number of new jobs is estimated at 524. It was calculated that the annual avoided carbon dioxide emissions will amount to 4.4 million tons, which will reduce Poland’s emissions by 1.4%. The construction... [more]

Space nuclear reactor power system (SNRPS) is a priority technical solution to meet the future space power requirement of high-power, low-mass, and long-life. The thermoelectric conversion subsystem is the key component of SNRPS, which greatly affects the performance, quality, and volume of SNRPS. Among all kinds of proposed thermoelectric conversion technologies, the free-piston Stirling power converter (FPSPC) has become a preferred conversion technology for small-scale advanced SNPRS due to its moderate waste heat emission temperature and high conversion efficiency, mainly composed of a linear alternator and free-piston Stirling engine (FPSE). For studying the performance of FPSPC, a quasi-steady flow thermodynamic cycle analysis model considering parasitic heat losses has been developed for FPSE. And then the performance analysis model for FPSPC has been established by coupling the thermodynamic cycle analysis model with the mechanical motion model of the piston and volt-ampere cha... [more]

Shale reservoir heterogeneity is strong, which seriously affects shale gas reservoir evaluation and reserves estimation. The Longmaxi Formation shale of the Luzhou block in southern Sichuan was taken as an example to characterize the pore distribution of shale over the full scale using micro-computed tomography (CT), focusing on ion beam scanning electron microscopy (FIB-SEM) and small-angle neutron scattering (SANS); further, the heterogeneity of the shale pore distribution over the full scale was explored quantitatively within different scales. The results show that shale micropores are dominated by microfractures that are mainly developed along the bedding direction and associated with organic matter, contributing 1.24% of porosity. Shale nanopores are more developed, contributing 3.57−4.72% porosity and have strong heterogeneity locally at the microscale, but the pore distribution characteristics show lateral homogeneity and vertical heterogeneity at the macroscale. In the same lay... [more]

Cooking conditions affect oil properties and consequently, the quality of the derived biodiesel. Nevertheless, little information regarding the impact of the cooking process on biodiesel properties is currently available, especially for palm biodiesel. Therefore, this study examined the effect of cooking temperature, time of use, and length of reuse, on selected properties of biodiesel produced from palm-based waste cooking oils (WCO). Several WCO collected from restaurants belonging to four categories, namely fried chicken restaurants, fast food restaurants, snack producers, and typical restaurants, were subjected to base-catalyzed transesterification. The biodiesel yield was calculated, and the produced biodiesel was characterized as to its kinematic viscosity, calorific value, and cetane number. As a result, palm-based WCO performed better than other WCO in terms of biodiesel yield regardless of the conditions that they experienced, achieving almost 95% in some cases. The yield decr... [more]

Xylose is the second most abundant monomeric sugar on earth. Nevertheless, metabolizing xylose into ethanol is a complex process due to several biochemical reactions. Some microorganisms of the genus Mucor are suitable for this bioprocess. Using metal ions, such as zinc and calcium, allows some fungal species to increase their ethanol yield. In this work, the wild strain Mucor spp. (C1502) was molecularly identified via internal transcribed spacer (ITS) sequencing. Secondly, an optimization using response surface methodology (RSM) with a central composite experimental design (CCD) was carried out. The independent variables (X) were ZnSO4·7H2O (X1, 0.0−1.5 g/L) and CaCl2 (X2, 0.0−2.5 g/L) concentration in the fermentation broth in order to demonstrate the effect of these ions, xylose was used as the only carbon source. The dependent variables (Y) measured were ethanol yield (Y1, g ethanol/g xylose) and xylitol yield (Y2, g xylitol/g xylose). The identified strain, Mucor circinelloides,... [more]

In the context of the great research pulse on clean energy transition, distributed energy systems have a key role, especially in the case of integration of both renewable and traditional energy sources. The stable interest in small-scale gas turbines can further increase owing to their flexibility in both operation and fuel supply. Since their not-excellent electrical efficiency, research activities on micro gas turbine (MGT) are focused on the performance improvements that are achievable in several ways, like modifying the Brayton cycle, integrating two or more plants, using cleaner fuels. Hence, during the last decades, the growing interest in MGT-based energy systems encouraged the development of many numerical approaches aimed to provide a reliable and effective prediction of the energy systems’ behavior. Indeed, numerical modeling can help to individuate potentialities and issues of each enhanced layout or hybrid energy system, and this review aims to discuss the various layout so... [more]

One of the main causes of damage to the elements of coal-fired boilers installations, leading to breakdowns and, consequently, a shutdown of the block, are erosive processes. Unfortunately, there is not much research conducted on dust erosion of the dust ducts supplying the air−dust mixture to the burners. The problem of erosion of the dust ducts supplying the pulverized coal−air mixture to the burners was presented in this paper. This study was performed for the preliminary feasibility design. The destruction of the material of the dust ducts results in a failure due to erosion, resulting in the mill being shut down from an operation, which in turn may lead to the shutdown of the power plant unit. Therefore, it is important to identify places exposed to pulverized coal erosion. In order to perform calculations, numerical modeling in the commercial program Ansys.Fluent (Ansys Fluent, Computational Fluid Dynamics, Ansys Inc., Pittsburgh, PA, USA) was used. The parameters obtained as a r... [more]

The study of the thermal safety of emulsion explosives mixed with waste engine oil is very important for the safety of these types of explosives used in mine blasting. In order to study the thermal safety of emulsion explosives mixed with waste engine oil, thermal safety tests were carried out using a Differential Scanning Calorimeter (DSC), non-isothermal kinetics, and the Flynn−Wall−Ozawa method. The results show that the minor particle impurities in the filtered waste engine oil are mainly combustibles; after adding different amounts of waste engine oil, the activation energy of the emulsion matrix decreases from 110.33 kJ/mol to 75.39 kJ/mol, 74.50 kJ/mol, and 82.23 kJ/mol, and the critical temperature for thermal explosion changes from 194.16 °C to 169.73 °C, 227.47 °C, and 208.78 °C. The addition of waste engine oil reduces the activation energy of emulsion explosives. The waste engine oil is negatively correlated with the activation energy and the thermal explosion reaction temp... [more]

The paper presents and discusses modern methods and technologies of CO2 capture (pre-combustion capture, post-combustion capture, and oxy-combustion capture) along with the principles of these methods and examples of existing and operating installations. The primary differences of the selected methods and technologies, with the possibility to apply them in new low-emission energy technologies, were presented. The following CO2 capture methods: pre-combustion, post-combustion based on chemical absorption, physical separation, membrane separation, chemical looping combustion, calcium looping process, and oxy-combustion are discussed in the paper. Large-scale carbon capture utilization and storage (CCUS) facilities operating and under development are summarized. In 2021, 27 commercial CCUS facilities are currently under operation with a capture capacity of up to 40 Mt of CO2 per year. If all projects are launched, the global CO2 capture potential can be more than ca. 130−150 Mt/year of ca... [more]

Modern-day buildings have become the third-largest consumer of energy, after industry and agriculture, and energy consumption in buildings contributes up to 40% of the total energy use in developed countries [...]

In this work, nickel silicide was applied to tandem solar cells as an interlayer. By the process of thermal evaporation, a layer of NiOx, hole transport layer (HTL) was deposited on n+ poly-Si layer directly. Nickel silicide was simultaneously formed by nickel diffusion from NiOx to n+ poly-Si layer during the deposition and annealing process. The I−V characteristics of NiOx/n+ poly-Si contact with nickel silicide showed ohmic contact and low contact resistivity. This structure is expected to be more advantageous for electrical connection between perovskite top cell and TOPCon bottom cell compared to the NiOx/TCO/n+ poly-Si structure showing Schottky contact. Furthermore, nickel silicide and Ni-deficient NiOx thin film formed by diffusion of nickel can improve the fill factor of the two sub cells. These results imply the potential of a NiOx/nickel silicide/n+ poly-Si structure as a perovskite/silicon tandem solar cell interlayer.

To investigate primary breakup close to an injector, this paper presents both experimental and numerical research on high-pressure common-rail diesel injection. We propose a new method named SD-ELSA model to realize automatically identifying droplet features for high-pressure diesel spray based on the classic ELSA (Eulerian Lagrangian Spray Atomization) model; this method is suitable for varied injection operation conditions. The SD-ELSA first identifies the liquid bulk due to breakup of the continuous phase in near field, and then converts the Eulerian liquid bulk into Lagrangian particles to complete the calculation of the total spray atomization. The SD-ELSA model adopts two key criteria, i.e., the sphericity (S) and the particle diameter (D); the qualified liquid mass is transformed into Lagrangian particle, realizing the coupling of the Eulerian−Lagrangian model. The SD-ELSA model illustrates the total diesel spray atomization process from the breakup liquid column to the droplets... [more]

The purpose of the research is to study the aerodynamics and heat transfer in the duct of a high-temperature recuperation system. The object of the research is a flat duct with a thickness-to-height ratio a:b = 1:10, length c = 400·a with one-sided heat input to the duct surface, complicated heat transfer and mixed air movement in the duct. The objectives of the research are to determine: (a) average temperatures on the duct surfaces; (b) air temperature distribution along the length of the duct; (c) local and average integral temperature values along the length of the duct; (d) local and average integral heat flow densities on the duct surfaces; (e) local and average integral heat exchange coefficients and Nusselt numbers on the duct surfaces; and (f) pressure distribution along the length and total pressure drop in the duct. The research method is based on conducting a mathematical numerical experiment in a stationary three-dimensional Cartesian formulation and physical modeling of p... [more]

This paper proposes the Compound Inverse Rayleigh distribution as a proper model for the characterization of the probability distribution of extreme values of wind-speed. This topic is gaining interest in the field of renewable generation, from the viewpoint of assessing both wind power production and wind-tower mechanical reliability and safety. The first part of the paper illustrates such model starting from its origin as a generalization of the Inverse Rayleigh model by means of a continuous mixture generated by a Gamma distribution on the scale parameter, which gives rise to its name. Moreover, its validity for interpreting different field data is illustrated resorting to real wind speed data. Then, a novel Bayes approach for the estimation of such extreme wind-speed model is proposed. The method relies upon the assessment of prior information in a practical way, that should be easily available to system engineers. The results of a large set of numerical simulations—using typical v... [more]

The article presents a numerical study of the large-amplitude, acoustically-driven streaming flow for different frequencies of the acoustic wave and different temperature gradients between hot and cold surfaces. The geometries studied were mainly two-dimensional rectangular resonators of different lengths, but also one three-dimensional rectangular resonator and one long and narrow channel, representative of a typical U-shaped resistance thermometer. The applied numerical model was based on the Navier−Stokes compressible equations, the ideal gas model, and finite volume discretization. The oscillating wall of the considered geometries was modeled as a dynamically moving boundary of the numerical mesh. The length of the resonators was adjusted to one period of the acoustic wave. The research confirmed that baroclinic acoustic streaming flow was largely independent of frequency, and its intensity increased with the temperature gradient between the hot and cold surface. Interestingly, a s... [more]

Nowadays, energy is becoming more electrical in each field of engineering application, thus power converters have assumed an increasingly relevant role for electrical machines, renewable energy and transportation systems [...]

In the Special Issue of Energies entitled Energy Efficiency in Buildings Both New and Rehabilitated that was published in 2019, a broad spectrum of research teams from around the world provided their latest findings on how to reduce energy consumption in the building sector [...]

This paper deals with a photovoltaic (PV) system containing a quasi-Z-source inverter (qZSI) and batteries connected in parallel with the qZSI’s lower-voltage capacitor. The control system design is based on knowledge of three transfer functions which are obtained from the novel small-signal model of the considered system. The transfer function from the d-axis grid current to the battery current has been identified for the first time in this study for the considered system configuration and has been utilized for the design of the battery current control loop for the grid-tied operation. The transfer function from the duty cycle to the PV source voltage has been utilized for the design of the PV source voltage control loop. The PV source voltage is controlled so as to ensure the desired power production of the PV source. For the maximum power point tracking, a perturb-and-observe algorithm is utilized that does not require the measurement of the PV source current, but it instead utilize... [more]

This article attempts to evaluate the My Electricity program concerning increasing renewable energy production in photovoltaic (PV) prosumer sources (PV micro-installations) in Poland. The assessment is made from the perspective of beneficiaries, business, and local community. One may also find an answer to the question of how this program should be modified so that it continues to support the development of PV systems in Poland. Moreover, how Poles assess the PV technology, in terms of the safety of its users and its impact on the environment, is studied. For this purpose, there was exploratory, qualitative, and quantitative research conducted. Twelve case studies were used as well as online questionnaires conducted on prosumers who used the My Electricity program to install PV micro-installations (57 respondents). By means of interviews, there was a confrontation of their point of view with the opinions of seven skeptics of such installations. Moreover, five experts from the energy i... [more]

Solar photovoltaic energy has experienced significant growth in the last decade, as well as the challenges related to the intermittency of power generation inherent to this process. In this paper we propose to perform short-term forecasting of solar PV generation using fuzzy time series (FTS). Two FTS methods are proposed and evaluated to obtain a global horizontal irradiance (GHI) value. The first is the weighted method and the second is the fuzzy information granular method. Using the direct proportionality of the power with the GHI, the spatial smoothing process was applied, obtaining spatial irradiance on which a first-order low pass filter was applied to simulated power photovoltaic system generation. Thus, this study proposed indirect and direct forecasting of solar photovoltaic generation which was statistically evaluated and the results showed that the indirect prediction showed better performance with GHI than the power simulation. Error statistics, such as RMSE and MBE, show... [more]

The wholesale electricity and capacity market constitute the backbone of the Russian power industry. It is in this market that large suppliers and buyers operate, and its entire turnover is consequently transmitted to the retail market. Our paper presents a theoretical overview of the main tools for forming the cost of electricity and capacity in the wholesale market in Russia (depending on the regional affiliation), the type of end users, and the degree of state participation. We consider the specifics of the formation of the cost of electricity and capacity in the price and non-price wholesale markets of Russia, which differ in territorial, climatic, and economic characteristics, as well as the established structure of generation. In the empirical part of the paper, we carry out a structural analysis of the volumes of trade in electricity and capacity in the price and non-price zones of the market. Furthermore, we explain the reasons for the current dynamics of prices in the wholesal... [more]

Single planar fuel cell elements consisting of metallic interconnectors that are bonded and sealed by a thin glass solder layer form the core of a solid oxide fuel cell. For reliable operation, the bonding layer has to adhere well and must be without voids or foreign material inclusions, which might cause gas leakage, electrical shorts or mechanical weakening and structural failure. Nondestructive testing (NDT) by the high-frequency ultrasound in immersion technique and by air-coupled ultrasound was optimized to find such defects. Another technique was flash light excited thermography for detection of voids. The NDT techniques used are complementary to each other, as they are based on different physical principles. Voids and small steel platelets of different sizes were prepared in the glass solder layer before the high-temperature bonding process and then monitored by the NDT techniques through the interconnector plates. Two selected NDT techniques were then validated in a probability... [more]

Gas accidents threaten the safety of underground coal mining, which are always accompanied by abnormal gas concentration trend. The purpose of this paper is to improve the prediction accuracy of gas concentration so as to prevent gas accidents and improve the level of coal mine safety management. Combining the LSTM model with the LightGBM model, the LSTM-LightGBM model is proposed with variable weight combination method based on residual assignment, which considers not only the time subsequence feature of data, but also the nonlinear characteristics of data. During the data preprocessing, the optimal parameters of gas concentration prediction are determined through the analysis of the Pearson correlation coefficients of different sensor data. The experimental results demonstrate that the mean absolute errors of LSTM-LighGBM, LSTM and LightGBM are 1.94%, 2.19% and 2.77%, respectively. The accuracy of LSTM-LightGBM variable weight combination model is better than that of the two above mo... [more]

The problem of rock mechanics and engineering is an old and new subject encountered by human beings in their struggle with nature for survival and development [...]