In the present study, the real-world performance of a ground-to-air heat exchanger (GAHE) was analyzed in the Polish climate which is characterized by warm summers and cold winters. The heat exchanger’s performance was monitored over a period of three years (2017 to 2019), and real-world conditions were compared with a Typical Meteorological Year (TMY). The aim of the study was to assess the exchanger’s energy-efficiency potential in various ventilation scenarios in a single-family home under variable real-world conditions, rather than to simply determine its heating and cooling capacity. The analyzed single-family home was a modern, single-story building with a usable floor area of 115 m2. The building’s thermal insulation and airtightness met stringent energy-efficiency standards. Energy consumption in a building equipped with a natural ventilation system was compared with three other scenarios: ventilation coupled with a GAHE, mechanical ventilation with heat recovery and a high-eff... [more]

Photovoltaic-thermal (PVT) collectors are hybrid solar collectors that convert solar and ambient energy into thermal and electrical energy. Integrated PVT-HP, in which PVT collectors are combined with a heat pump, offers an efficient and renewable option to replace conventional fossil fuel-based energy systems in residential buildings. Currently, system concepts in which the selection, design and control of the components are aligned towards the system performance are lacking. The development of a system model enables the comparison of a variety of system parameters and system designs, informed decision making based on the energetic performance and the market diffusion of PVT-HP systems. This contribution presents a simulation model of a PVT-HP system. By means of numerical simulations, with simulation program TRNSYS, the energetic performance of a PVT-HP system and the system components are investigated. It is shown that the PVT-HP can cover the annual energy demand of a residential b... [more]

Roof bolting is the most popular type of support for underground mines’ workings. However, in Polish coal mines it is used only as a supplementary support. To raise the effectiveness and economic score of horizontal development works, JSW (Jastrzębska Spółka Węglowa) started a project to introduce the independent rock bolting support in its mines. The key element of the project is the monitoring of mine workings supported with roof bolting, as appropriate control allows one to ensure a proper level of safety. The following work presents a monitoring system for mine working supported with roof bolting applied in the project, as well as results of the measurements obtained using this system. The aim of the monitoring was to prove that independent roof bolting provides a proper level of safety and thus is applicable in conditions of Polish underground coal mines, particularly Budryk mine. It was to be proved by the evaluation of data obtained from instrumented bolts, extensometers of diff... [more]

The energy transition from inefficient fossil-based to sustainable energy systems can face various lock-ins. There are no pathways that are free of stress. However, many routes are possible. A good understanding of the dynamic behavior of systems is crucial, and proper support tools are needed to assess the outcomes of every selected pathway. This study aims to develop an Internet-based interface tool for the national energy simulation model as a tool for a “hybrid forum”; study energy transition lock-ins in one of the Eastern European countries; and apply the interface tool to study different pathways to Latvia’s climate and energy goals. System dynamics are used to reach the goals of the study. A causal loop diagram is applied to study feedback loops and lock-ins, a stock-and-flow structure is used to build a simulation model, and a user interface tool is built on top of it. The results show that the developed interface tool is user-friendly and can be used as a discussion platform.... [more]

Inlet temperature is vital to the thermal efficiency of gas turbines, which is becoming increasingly important in the context of structural changes in power supplies with more intermittent renewable power sources. Blade cooling is a key method for gas turbines to maintain high inlet temperatures whilst also meeting material temperature limits. However, the implementation of blade cooling within a gas turbine—for instance, thermal barrier coatings (TBCs)—might also change its heat transfer characteristics and lead to challenges in calculating its internal temperature and thermal efficiency. Existing studies have mainly focused on the materials and mechanisms of TBCs and the impact of TBCs on turbine blades. However, these analyses are insufficient for measuring the overall impact of TBCs on turbines. In this study, the impact of TBC thickness on the performance of gas turbines is analyzed. An improved mathematical model for turbine flow passage is proposed, considering the impact of coo... [more]

This paper focuses on the estimation of energy consumption of Electric Vehicles (EVs) by means of models derived from traffic flow theory and vehicle locomotion laws. In particular, it proposes a bi-level procedure with the aim to calibrate (or update) the whole parameters of traffic flow models and energy consumption laws by means of Floating Car Data (FCD) and probe vehicle data. The reported models may be part of a procedure for designing and planning transport and energy systems. This aim is to verify if, and in what amount, the existing parameters of the resistances/energy consumptions model calibrated in the literature for Internal Combustion Engines Vehicles (ICEVs) change for EVs, considering the above circular dependency between supply, demand, and supply−demand interaction. The final results concern updated parameters to be used for eco-driving and eco-routing applications for design and a planning transport system adopting a multidisciplinary approach. The focus of this manu... [more]

International policies for sustainable development have led to an increase in distributed power production based on renewable resources [...]

This article presents a power to SNG (synthetic natural gas) system that converts hydrogen into SNG via a methanation process. In our analysis, detailed models for all the elements of the system are built. We assume a direct connection between a wind farm and a hydrogen generator. For the purposes of our calculations, we also assume that the hydrogen generator is powered by the renewable source over a nine-hour period per day (between 21:00 and 06:00), and this corresponds to the off-peak period in energy demand. In addition, a hydrogen tank was introduced to maximize the operating time of the methanation reactor. The cooperation between the main components of the system were simulated using Matlab software. The primary aim of this paper is to assess the influence of various parameters on the operation of the proposed system, and to optimize its yearly operation via a consideration of the most important constraints. The analyses also examine different nominal power values of renewables... [more]

Faced with key obstacles, such as the short driving range, long charging time, and limited volume allowance of battery-powered electric light scooters in Asian cities, the aim of this study is to present a passive fuel cell/battery hybrid system without DC-DC to ensure a compact volume and low cost. A novel topology structure of the passive fuel cell/battery power system for the electric light scooter is proposed, and the passive power system runs only on hydrogen. The power performance and efficiency of the passive power system are evaluated by a self-developed test bench before installation into the scooters. The results of this study reveal that the characteristics of stable power output, quick response, and the average efficiency are as high as 88% during the Shanghainese urban driving cycle and 89.5% during the Chinese standard driving cycle. The results present the possibility that this passive fuel cell/battery hybrid powertrain system without DC-DC is practical for commercial s... [more]

In this paper, the authors present an overview of biomass gasification modeling approaches with the aim of evaluating their effectiveness as a modeling tool for the design and optimization of polygeneration plants based on biomass gasification. In fact, the necessity to build plant operating maps for efficiency optimization requires a significant number of simulations, and non-stoichiometry equilibrium models may allow fast computations thanks to their relative simplicity. The main objective consists of the assessment of thermodynamic equilibrium models performance as a function of biomass type and composition to better understand in which conditions of practical interest such models can be applied with acceptable reliability. To this aim, the authors developed two equilibrium models using both a commercial software (referred as Aspen model) and a simulation tool implemented in a non-commercial script (referred as analytical model). To assess their advantages and disadvantages, the two... [more]

Studying and analyzing the challenges that the renewable energy sector faces can help evaluate the risks and improve the planning. This research is done by considering the challenges in the implementation of sustainable generation of electricity through RESs in India, based on factors, including technical, financial, involvement, support, and others. The triangular fuzzy number (TFN) method, based on fuzzy logic concept, is used to analyze the challenges in this study. In general, TFN comprises of three numbers, likewise Gaussian fuzzy numbers, trapezoidal fuzzy numbers also exist. The classified sets of numbers are denotations to decision-makers’ perspective or a choice towards the criterion preference. Although alternatives are many to design a fuzzy set depending on elements count, the TFNs are the ones considered as actual representations of a fuzzy number. On the other hand, cases the Gaussian or trapezoidal, are manifestations of fuzzy intervals. Another argument is that the memb... [more]

Temperature is considered to be an important indicator that affects the capacity of a lithium ion batteries. Therefore, it is of great significance to study the relationship between the capacity and temperature of lithium ion batteries with different anodes. In this study, the single battery is used as the research object to simulate the temperature environment during the actual use of the power battery, and conduct a charge and discharge comparison test for lithium iron phosphate battery, lithium manganate battery and lithium cobalt oxide battery. In the test of capacity characteristics of lithium ion batteries of three different cathode materials at different temperatures, the optimal operating temperature range of the lithium ion battery is extracted from the discharge efficiencies obtained. According to the research results, the discharge capacity of a lithium ion battery can be approximated by a cubic polynomial of temperature. The optimal operating temperature of lithium ion batt... [more]

The aim of this article was to investigate the possible relationship between energy production and GDP growth. This problem is of a crucial importance because as a numerous studies show, it is difficult to give an unambiguous answer to the question of whether there is a relationship between GDP and energy production and what direction it takes if it exists, i.e., whether energy production drives GDP growth or GDP growth drives energy production. The research conducted by the authors used data on hourly power production in MWh/h averaged over a whole day, which were converted into total quarterly production. The data were divided in terms of the type of energy into conventional, renewable, other and total. Next, the correlation coefficient was calculated for proper data sets in order to determine whether there was a correlation between the variables. The main conclusion from the study is the fact that a correlation measured with the Pearson correlation coefficient is not reflected in th... [more]

In this article, we propose the parameters of a battery that would be suitable for the conceptual design of a small training aircraft. The mass design of the battery is based on the requirements for real training flights performed by students in pilot training. Such a serial hybrid propulsion aircraft could be used in our UNIZA aviation, training and education center for pilot training. Due to socio-political pressures in reducing emissions generated by vehicles, there has also been massive research in the aviation industry in the field of hybrid and electric aircraft propulsion. In the introduction, the article deals with the energy sources used in aircraft propulsion. In hybrid propulsion, a combination of aviation fuel and electricity is used as the energy source. The required total energy must choose a suitable combination of these two energy sources. The biggest drawback of batteries that can be used in hybrid systems is their low energy density. Low energy density means that larg... [more]

The emergence of mass-spectroscopy with inductively-coupled plasma (ICP-MS) made it possible to study the microelement composition of crude oil and its derivatives with the limit of detection (LOD) at the ppt level. We have studied the crudes from West Siberian (Shaimsky, Sredneobsky and Oktyabrsky regions) and Tatarstan Romashinskoye oilfields with the ICP-MS method to detect 50 rare, rare-earth, and other microelements. The elemental composition is reasonably comparable to their concentrations in ultrabasites whereas the contents of most of the elements are low to the limit. On the diagrams of rare-earth elements, one can see the prevalence of light lanthanides and positive europium anomaly. Increased content of platinoids was found in Tatar oils; in some cases, the concentration of ruthenium reaches 0.06 g/t. The study shows that studied crudes have a specific microelement composition. Based on the elevated contents of transit elements and platinoids, a conclusion was made about the... [more]

The electricity sector in the 21st century should be associated with renewable energy sources (RES), which the majority of society currently equates with solar photovoltaics, wind power, and hydroelectricity, with this energy being used mainly in households. Households consume only 20% of energy, with the remainder used in various sectors of the national economy. In these sectors, the possibilities of using renewable energy sources should be sought. Many experts express the opinion that myths about renewable energy sources exist only “in our minds and opinions, that we formed years ago”, mainly under pressure from the decreasing number of supporters of conventional energy sources. Currently, we observe much greater possibilities of using renewable energy sources globally, and all forecasts suggest that—by 2050—the economy, transport, and industry may become almost emission-free and rely on RES. Of course, we cannot present renewable energy sources only in terms of superlatives, because... [more]

This paper proposes a step-up DC−DC converter for a power electronic circuit for standalone photovoltaic systems with battery energy storages. The proposed DC−DC converter effectively converts low DC battery voltage into high DC-link voltage. It operates with soft-switching characteristics, which can reduce switching power losses. The proposed converter operates without output voltage feedback, which simplifies its control design. The operation principle of the proposed converter was described, along with the overall system configuration. The experimental results were discussed for the 500-W prototype system using a 12-V lead-acid battery.

We adopt a physics-guided, data-driven method to predict the most likely future production from the largest tight oil and gas deposits in North America, the Permian Basin. We first divide the existing 53,708 horizontal hydrofractured wells into 36 spatiotemporal well cohorts based on different reservoir qualities and completion date intervals. For each cohort, we fit the Generalized Extreme Value (GEV) statistics to the annual production and calculate the means to construct historical well prototypes. Using the physical scaling method, we extrapolate these well prototypes for several more decades. Our hybrid, physico-statistical prototypes are robust enough to history-match the entire production of the Permian mudstone formations. Next, we calculate the infill potential of each sub-region of the Permian and schedule the likely future drilling programs. To evaluate the profitability of each infill scenario, we conduct a robust economic analysis. We estimate that the Permian tight reserv... [more]

Modern wind turbines depend on their blade pitch systems for start-ups, shutdowns, and power control. Pitch system failures have, therefore, a considerable impact on their operation and integrity. Hydraulic pitch systems are very common, due to their flexibility, maintainability, and cost; hence, the relevance of diagnostic algorithms specifically targeted at them. We propose one such algorithm based on sensor data available to the vast majority of turbine controllers, which we process to fit a model of the hydraulic pitch system to obtain significant indicators of the presence of the critical failure modes. This algorithm differs from state-of-the-art, model-based algorithms in that it does not numerically time-integrate the model equations in parallel with the physical turbine, which is demanding in terms of in situ computation (or, alternatively, data transmission) and is highly susceptible to drift. Our algorithm requires only a modest amount of local sensor data processing, which... [more]

Rail transport, specifically diesel−electric trains, faces fundamental challenges in reducing fuel consumption to improve financial performance and reduce GHG emissions. One solution to improve energy efficiency is the electric brake regenerative technique. This technique was first applied on electric trains several years ago, but it is still considered to improve diesel−electric trains efficiency. Numerous parameters influence the detailed estimation of brake regenerative technique performance, which makes this process particularly difficult. This paper proposes a simplified energetic approach for a diesel−electric train with different storage systems to assess these performances. The feasibility and profitability of using a brake regenerative system depend on the quantity of energy that can be recuperated and stored during the train’s full and partial stop. Based on a simplified energetic calculation and cost estimation, we present a comprehensive and realistic calculation to evaluat... [more]

The aim of the study is to assess the influence of the atmosphere during pyrolysis on the course of CO2 gasification of a tire waste char. Two approaches were used: the pyrolysis step was carried out in an inert atmosphere of argon (I) or in an atmosphere of carbon dioxide (II). The examinations were carried out in non-isothermal conditions using a Rubotherm DynTherm thermobalance in the temperature range of 20−1100 °C and three heating rates: 5, 10 and 15 K/min. Based on the results of the gasification examinations, the TG (Thermogravimetry) and DTG (Derivative Thermogravimetry) curves were developed and the kinetic parameters were calculated using the KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. Additionally, the CO2 gasification of tire chars reaction order (n), was evaluated, and the kinetic parameters were calculated with the use of Coats and Redfern method. Tire waste char obtained in an argon atmosphere was characterized by lower reactivity, which was refle... [more]

Oxidative depolymerization of low-rank coals is promising for obtaining benzene carboxylic acids (BCAs). However, it is hindered by the low yield of BCAs along with a large number of alphatic acids. Thermal dissolution could modify the physico-chemical structural features of low-rank coals, which is expected to improve the oxidation of LRCs. In this paper, lignite and subbituminous coal were firstly subjected to thermal dissolution with cyclohexane at 250 °C for 2 h. Then, the raw coal and the corresponding thermal insoluble portion (TIP) were oxidized by NaOCl under the same conditions. The residual yields of TIPs oxidation were both lower than those of raw coals oxidation, indicating that TIPs were more easily oxidized than the raw coals. The yield of BCAs obtained by TIPs oxidation was above 19% higher than that from the oxidation of raw coals. Meanwhile, the selectivity of BCAs was improved in the resulting oxidation products from TIPs compared with that from the raw coals. The rel... [more]

It has become a basic requirement for wind turbines (WTs) to provide frequency regulation and inertia support. The influence of WTs on the low-frequency oscillation (LFO) of the system will change after adopting inertia control methods. This paper intends to investigate and compare in detail the IC effects on LFO characteristics in two systems with different structures. First, the mechanism of inertia control of doubly fed induction generator (DFIG)-based WTs is analyzed. Then, the small-signal analysis method and modal analysis method are used to study the influence of the inertia control on the LFO characteristics based on the two-machine infinite-bus system and the four-machine two-area system, respectively. The difference in impact rules of IC on LFO is compared in detail. Finally, considering that the inertia control might worsen the LFO in some systems, an improved inertia control strategy of DFIG-based WTs is proposed to suppress the LFO. The simulation results demonstrate that,... [more]

The use of solar panels in low-power applications is an increasingly developing topic. Various methods are currently used to obtain the highest possible solar panel power generation efficiency. The methods of determining the maximum power point (MPP) and its tracking are under constant development, resulting in the creation of new algorithms to accelerate the operational efficiency while maintaining good parameters. Typically, these methods are only used in high-power photovoltaic installations. Due to the problems resulting from the adjustment to MPP working conditions for low-power solar panels used to charge a Li-Ion battery, an attempt was made to check the feasibility of operating control based on a Pulse Width Modulation (PWM) method and a Maximum Power Point Tracking (MPPT) algorithm like the one used in high-power solar systems also for low-power systems. The article presents adaptation of PWM and MPPT methods for small chargers, including the stages of modelling a solar charge... [more]

Acid treatments are one of the methods for intensifying oil and gas production. Corrosion is a significant factor affecting the performance of oilfield equipment. There are many different methods of preventing corrosion, but corrosion inhibitors are most commonly used in industry. The protective effect of the inhibitor is directly determined by the effective adsorption of surfactants on the metal surface. For an indirect assessment of the adsorption of the inhibitor, a comprehensive research method is proposed based on the determination of the interfacial tension of acid compositions and steel plates’ contact angle of wetting after corrosion tests. It was found that in hydrochloric acid the adsorption of the inhibitor IC-1 reaches a maximum after 6 h, an increase in the acid concentration in the range of 5−15% wt. has a negative effect on the activity of the inhibitor. For sulfamic acid, the maximum adsorption of the IC-2 inhibitor is observed after 24 h, an increase in acid concentrat... [more]