Water extraction from air, based on reverse cycle systems, is becoming a technology more and more diffused and various models of air to water generators (AWG) are now available, all claiming the best efficiency. To date, there is not a standard indicator stating energy efficiency for AWGs, neither in the literature nor in technical practice. The only evaluation parameter, that can be found is a sort of specific energy consumption (SEC) without any clear indications about the involved calculation terms, definition of hypotheses, or environmental conditions. The current work is a first proposal of an indicator to standardise the AWG efficiency evaluation. The indicator is called WET (Water Energy Transformation); it states water production as a useful effect of an AWG machine and calculates its energy performance with an approach similar to COP (Coefficient of Performance) and EER (Energy Efficiency Ratio) evaluation. The indicator is meant to be a normalised tool that permits comparing... [more]

The percentage of heat pumps used in thermal power plants (TPPs) in the fuel and energy balance is extremely low in in most countries. One of the reasons for this is the lack of a systematic approach to selecting and justifying the circuit solutions and equipment capacity. This article aims to develop a new method of calculating the maximum capacity of heat pumps. The method proposed in the article has elements of marginal analysis. It takes into account the limitation of heat pump capacity by break-even operation at electric power market (compensation of fuel expenses, connected with electric power production). In this case, the heat pump’s maximum allowable capacity depends on the electric capacity of TPP, electricity consumption for own needs, specific consumption of conditional fuel for electricity production, a ratio of prices for energy resources, and a conversion factor of heat pump. For TPP based on combined cycle gas turbine (CCGT) CCGT-450 with prices at the Russian energy re... [more]

During the past years, researchers have studied both numerically and experimentally multibody wave-wind combined energy structures supporting wind turbines and different types of Wave Energy Converters (WECs); rigid body hydrodynamic assumptions have been adopted so far for the development of their numerical models and the assessment of their produced power. In the present paper a numerical model that is based on the use of generalized modes addressing wave-structure interaction effects for the case of a multibody wave-wind combined structure is developed and presented. Afterwards, the developed numerical model is used for the assessment of the hydrodynamic response and the prediction of the produced power of different possible configurations of the updated WindWEC concept which consists of a spar supporting a wind turbine and one, two, three or four heaving type WEC buoys. The combined effects of the center-to-center distance of the WEC and spar platform, the number of the WECs and th... [more]

The flagship project in this area in Poland is the Electromobility Development Program, one of the strategic documents of which is the Act on Electromobility and Alternative Fuels of 11 January 2018, which includes a system of benefits aimed at influencing consumer behaviors towards the choice of electric vehicles. According to the decision-makers, its implementation is expected to result in the achievement of a number of goals, among others, 1 million of such vehicles are forecast to be present at the national level in 2025. The intention of the authors is to analyze the progress in the development of electromobility in Poland, in the areas such as the market of electric cars, charging infrastructure, with an indication of whether the actions that are implemented by the legislator, i.e., guidelines on where and in what quantities charging stations dedicated to such vehicles are to be established, subsidies in the form of the possibility of driving on the lanes designed for buses, subs... [more]

In longwall top coal caving (LTCC), the resource recovery ratio of the working face is directly determined by the top coal recovery ratio. An investigation of the evolution of top coal drawing characteristics and revealing the evolution of top coal drawing parameters is necessary when providing guidance for caving parameter selection and improving the top coal recovery ratio. Based on in-situ measurements of the size distribution of caved top coal blocks in Wangjialing coal mine, a finite difference method (FDM)−discrete element method (DEM) coupled method was applied to establish a “continuous−discontinuous” numerical model and the process from the first coal drawing to the common coal drawing was simulated with 17 separate working face advances. The evolution of the drawing body (DB), loose body (LB), and top coal boundary (TCB) was obtained. The results show that, the evolution of parameters of DB such as shape and size, drawing amount, length and deflection angle of the long axis o... [more]

Environmental problems such as air pollution and greenhouse gas emissions are especially challenging in urban areas. Electric mobility in different forms may be a solution. While in recent years a major focus was put on private electric vehicles, e-mobility in public transport is already a very well-established and mature technology with a long history. The core objective of this paper is to analyze the economics of e-mobility in the Austrian capital of Vienna and the corresponding impact on the environment. In this paper, the historical developments, policy framework and scenarios for the future development of mobility in Vienna up to 2030 are presented. A major result shows that in an ambitious scenario for the deployment of battery electric vehicles, the total energy demand in road transport can be reduced by about 60% in 2030 compared to 2018. The major conclusion is that the policies, especially subsidies and emission-free zones will have the largest impact on the future developme... [more]

Renewable energy and environmental issues are receiving considerable attention worldwide along with the technological development of production system for reducing global warming. Due to the use of smart technologies, the rate of carbon emission and energy utilization have become very high and are directly related to different industries. This study focuses on the effect of renewable energy on the advancement of smart production with a flexible production rate as well as the reduction of carbon emission to build a sustainable smart production system. A mathematical model is developed to maximize the profit of the smart production system for economic development while considering technological and environmental issues. The model is solved analytically, and we obtain closed and quasi-closed form solutions. A numerical experiment is performed, and a comparison with previous studies indicates that our method achieves more profit than existing ones. Additionally, we highlight the major effe... [more]

The inconsistency in large-scale battery pack significantly degrades the performance of electric vehicles. In order to diminish the inconsistency, the study designs an active equalization method comprising of equalizer and equalization strategy for lithium-ion batteries. A bidirectional flyback transformer equalizer (BFTE) is designed and analyzed. The BFTE is controlled by a pulse width modulation (PWM) controller to output designated balancing currents. Under the purpose of shortening equalization time and reducing energy consumption during the equalization process, this paper proposes an equalization strategy based on variable step size generalized predictive control (VSSGPC). The VSSGPC is improved on the generalized predictive control (GPC) by introducing the Step Size Factor. The VSSGPC surmounts the local limitation of GPC by expanding the control and output horizons to the global equalization process without increasing computation owing to the Step Size Factor. The experiment r... [more]

Sugar has the potential to create enough energy to power mobile electronics. Various sugar-powered fuel cells have been reported, however, most of them used pure glucose as substrate and enzymes/noble metals as catalysts. In this work, an alkaline fuel cell with cheap catalysts were constructed, and different sweet drinks were used as fuels for power generation. The influence of different substrates on the electrochemical performance was characterized under the controlled conditions. Our experimental results showed that the fuel cell fueled with carbonated soft drinks had the best performance under the conditions of 99.95 g/L chemical oxygen demand and 3M KOH. The power densities of the fuel cell fueled with different substrates decreased in the order of Pepsi (33.41 W/m2) > Sprite (28.38 W/m2) > apple juice (20.63 W/m2) > Coca (16.31 W/m2) > pear juice (15.31 W/m2) > orange juice (12.75 W/m2), which was consistent with linear sweep voltammetry (LSV) and electrochemical impedance spect... [more]

The basic function of the Park and Ride (P&R) facility is to allow users to leave their vehicle on the outskirts of the city and to continue their journey to the city center using means of public transport, e.g., bus, tram, trolleybus, subway, train, or bike. In the first part of the paper, an analysis of the selected factors related to the functioning of P&R facilities in Warsaw (Poland) was performed. The main purpose of this paper was to identify and quantify the influence factors determining the choice of P&R facility during a journey. This analysis was performed for three hypothetical journey scenarios. A list of potential factors determining the choice of P&R facility during travel was compiled after conducting previous research in this area and studying the worldwide scientific literature on the subject. The structural parameters of the multinomial logit model were estimated based on the data from the survey conducted in Warsaw. The results of the analyses indicate that the deci... [more]

In modern society, high-quality material development and a large stable supply are key to perform frontier research and development. However, there are negative issues to address to utilize high-quality resources with a large stable supply for research, such as economic accessibility, commercialization, and so on. One of the cutting-edge research fields, perovskite-related research, usually requires high-quality chemicals with outstanding purity (>99%). We developed an economically feasible PbI2 precursor with around 1/20 cost-down for perovskite/perovskite quantum dots through recrystallization and/or hydrothermal purification. Following the methodology, the quantum dots from both as-prepared and purified PbI2 demonstrated identical photophysical properties, with a photoluminescence quantum yield (PLQY) of 52.61% using the purified PbI2 vs. 45.83% PLQY using commercial PbI2. The role of hydrothermal energy was also checked against the problematic PbI2, and we checked whether the hydro... [more]

An experimental study was performed to investigate the effects of the arrangement of fan-shaped film cooling holes and density ratio (DR) on heat transfer coefficient augmentation. Both single- and multi-row fan-shaped film cooling holes were considered. For the multi-row fan-shaped holes, the heat transfer coefficient was measured at DRs of 1 and 2, and both staggered and inline arrangements of holes were considered. For the single-row fan-shaped holes, DR = 1.0, 1.5, 2.0, and 2.5 and M = 1.0 and 2.0 conditions were tested. The mainstream velocity was 20 m/s, and the turbulence intensity and boundary layer thickness were 3.6% and 6 mm, respectively. The heat transfer coefficient was measured using the one-dimensional transient infrared thermography method. The results show that an increased heat transfer coefficient augmentation is observed between film cooling holes for the case with a smaller hole pitch and higher blowing ratio. For the given fan-shaped hole parameters, the effects... [more]

The scope of this work was to develop a technique based on the regression method and apply it on a real cooled geometry for measuring its internal heat transfer distribution. The proposed methodology is based upon an already available literature approach. For implementation of the methodology, the geometry is initially heated to a known steady temperature, followed by thermal transient, induced by injection of ambient air to its internal cooling system. During the thermal transient, external surface temperature of the geometry is recorded with the help of infrared camera. Then, a numerical procedure based upon a series of transient finite element analyses of the geometry is applied by using the obtained experimental data. The total test duration is divided into time steps, during which the heat flux on the internal surface is iteratively updated to target the measured external surface temperature. The final procured heat flux and internal surface temperature data of each time step is u... [more]

Building integrated photovoltaic (BIPV) technologies are promising and practical for sustainable energy harvesting in buildings. BIPV products are commercially available, but their electrical power outputs in practice are negatively affected by several factors in outdoor environments. Performance improvement of BIPV applications requires mitigation approaches based on an understanding of these factors. A review was, therefore, conducted on this issue in order to providing guidance for practical applications in terms of the selection of proper PV technologies, temperature management, solar irradiation enhancement and avoidance of excessive mechanical strain. First, major types of PV cells used in BIPV applications were comparatively studied in terms of their electrical performances in laboratorial and outdoor environments. Second, temperature elevations were widely reported in outdoor BIPV applications, which may cause efficiency degradation, and the mitigation approaches may include ai... [more]

As traditional energy sources are increasingly depleting, ocean energy has become an emergent potential clean energy source. Wave energy, as an important part of ocean-derived energy, has been studied and utilized by coastal countries worldwide, which have developed various wave energy converters. In this paper, a new wave energy converter is designed, and water movement in fluid channels is analyzed. The results are, then, used to generate a mathematical model that simulates water movement. Based on this approach, the water movement state is analyzed, and a formula for calculating the natural frequency of water movement in the power generator is derived. The formula shows that the characteristic length of the water movement in the proposed generator and the backboard tilt angle at the exit point of the fluid channel are two design-related variables that can be used to alter the natural frequency; a regular wave experiment is conducted based on the fluid model, which is designed based... [more]

This work aims to evaluate the possible application of pyrolysis fuel oils obtained through the pyrolysis of waste plastics. by comparing both the blasting properties and morphology results of Ammonium Nitrate Fuel Oil (ANFO), which is applied in the mining industry, and ANFO based on pyrolysis fuel oils (FOs), as well as low-temperature properties of all tested FO samples. The low-temperature research includes the measurements of density, kinematic viscosity, flash point, pour point, and cloud point. Moreover, a stability analysis was carried out based on the Turbiscan Stability Index (TSI) coefficient. Based on the obtained results it was concluded that despite pyrolysis FOs showing some differences in comparison with index FO, none of their properties indicated that pyrolysis FOs should be excluded from possible application in ANFO. Additionally, IR, XRD, and SEM analyses were conducted for all ANFO samples. The instrumental analysis did not show any dribbling effect. The blasting t... [more]

The purpose of this work is to determine the impact of selected silage maize cultivation technologies, including energy inputs in the production chain (cultivation, harvesting, heap placing), on energy efficiency. The analysis of energy inputs, energy efficiency for the silage maize production technology were estimated. The research was performed for 13 farms producing silage maize. The data from the farms covered all the activities and the agrotechnical measures performed. The calculations of energy inputs made for the silage maize production for selected technologies were performed using the method developed by the Institute of Construction, Mechanization and Electrification for Agriculture (IBMER), once the method was verified and adapted to the needs and conditions of own research. Based on the accumulated energy production and the energy accumulated in the yield, energy efficiency index values for 13 silage maize cultivation technologies were calculated. The greatest impact on the... [more]

Significant changes in conventional generator operation and transmission system planning will be required to accommodate increasing solar photovoltaic (PV) penetration. There is a limit to the maximum amount of solar that can be connected in a service area without the need for significant upgrades to the existing generation and transmission infrastructure. This study proposes a framework for analyzing the impact of increasing solar penetration on generation and transmission networks while considering the responses of conventional generators to changes in solar PV output power. Contrary to traditional approaches in which it is assumed that generation can always match demand, this framework employs a detailed minute-to-minute (M-M) dispatch model capable of capturing the impact of renewable intermittency and estimating the over- and under-generation dispatch scenarios due to solar volatility and surplus generation. The impact of high solar PV penetration was evaluated on a modified bench... [more]

The aim of the paper was to summarize and discuss current research trends in biomass thermal treatment (torrefaction process). Quantitative analyses were carried out, in which the main countries, research units and scientists were indicated. The analysis showed a clear upward trend in number of publications after 2010. Most scientists on selected topics come from China, USA, Canada, South Korea, Republic of China, Poland (Web od Science—Core Collection (WoS-CC) and Scopus databases). Quantitative analysis also showed that the most relevant WoS-CC categories in the summary are: Energy Fuels, Engineering Chemical, Agricultural Engineering, Biotechnology Applied Microbiology and Thermodynamics and Scopus Subject area: Energy, Chemical Engineering, Environmental Science, Engineering and Chemistry. Thematic analysis included research topics, process parameters and raw materials used. Thematic groups were separated: torrefaction process (temp.: 150−400 °C), hydrothermal carbonization process... [more]

The rail transit system is a large electric vehicle system that is strongly dependent on the energy technologies of the power system. The use of new energy-saving amorphous alloy transformers can not only reduce the loss of rail transit power, but also help alleviate the power shortage situation and electromagnetic emissions. The application of the transformer in the field of rail transit is limited by the problem that amorphous alloy is prone to debris. this paper studied the stress conditions of amorphous alloy transformer cores under different working conditions and determined that the location where the core is prone to fragmentation, which is the key problem of smoothly integrating amorphous alloy distribution transformers on rail transit power supply systems. In this study, we investigate the changes in the electromagnetic field and stress of the amorphous alloy transformer core under different operating conditions. The finite element model of an amorphous alloy transformer is es... [more]

A probabilistic machine learning method is applied to icing related production loss forecasts for wind energy in cold climates. The employed method, called quantile regression forests, is based on the random forest regression algorithm. Based on the performed tests on data from four Swedish wind parks available for two winter seasons, it has been shown to produce valuable probabilistic forecasts. Even with the limited amount of training and test data that were used in the study, the estimated forecast uncertainty adds more value to the forecast when compared to a deterministic forecast and a previously published probabilistic forecast method. It is also shown that the output from a physical icing model provides useful information to the machine learning method, as its usage results in an increased forecast skill when compared to only using Numerical Weather Prediction data. A potential additional benefit in machine learning for some stations was also found when using information in the... [more]

In the design of modern power electronics converters, especially DC-DC converters, circuit-level computer simulations play an important role. This article analyses the accuracy of computations of the boost converter characteristics in the steady state using an electrothermal averaged model of a diode−transistor switch containing an Insulated Gate Bipolar Transistor (IGBT) and a rapid switching diode. This model has a form of a subcircuit for SPICE (Simulation Program with Integrated Circuit Emphasis). The influence of such factors as the switching frequency of the transistor, the duty cycle of the signal controlling the transistor, the input voltage, and the output current of the boost converter on the accuracy of computing the converter output voltage and junction temperature of the IGBT and the diode were analysed. The correctness of the computation results was verified experimentally. Based on the performed computations and measurements, the usefulness range of the model under consi... [more]

In order to calculate the financial return of energy efficiency measures, a cost−benefit analysis (CBA) is a proven tool for investors. Generally, however, most CBAs for investors have a narrow focus, which is—simply speaking—on investment costs compared with energy cost savings over the life span of the investment. This only provides part of the full picture. Ideally, a comprehensive or extended CBA would take additional benefits as well as additional costs into account. The objective of this paper is to reflect upon integrating into a CBA two important cost components: transaction costs and energy efficiency services—and how they interact. Even though this concept has not been carried out to the knowledge of the authors, we even go a step further to try to apply this idea. In so doing, we carried out a meta-analysis on relevant literature and existing data and interviewed a limited number of energy experts with comprehensive experience in carrying out energy services. Even though dat... [more]

Emissions from diesel engines can be limited and potentially decreased by modifying the fuel chemical composition through additive insertion. One class of additives that have shown to be particularly efficient in the reduction of the particulates from the combustion of diesel fuels are oxygenated compounds. In the present study we investigate the effect of tripropylene glycol methyl ether (TPGME) and two polyoxymethylene dimethyl ethers (POMDME or OMEs) on soot formation in a laminar diesel diffusion flame. From the evaluation of soot volume fraction by laser-induced incandescence (LII) measurements we could observe that OME additives have a substantial capability (higher compared to TPGME) to decrease the particle concentration, which drops by up to 36% with respect to the pure diesel fuel. We also note a reduction in particle aggregate size, determined by wide-angle light scattering (WALS) measurements, which is more pronounced in the case of OME−diesel blends. The effects we observe... [more]

Solar photovoltaic (PV) applications are gaining a great interest worldwide and dominating the renewable energy sector. However, the solar PV panels’ performance is reduced significantly with the increase in their operating temperature, resulting in a substantial loss of energy production and poor economic scenarios. This research contributes to overcoming the PV performance degradation due to the temperature rise. This work involves experimental and theoretical studies on cooling of PV panels using the evaporative cooling (EC) principle. A new EC design to cool the bottom surface of a PV panel was proposed, fabricated, tested, and modeled. A series of experimentation readings under real conditions showed the effectiveness of the method. A steady state heat and mass transfer model was implemented and compared with the experimental data. Fair agreement between the results of the modelling and experimental work was observed. It was found that the temperature of the PV panel can be decrea... [more]