In this paper, the research methodology and the results of the analysis carried out using the acoustic emission (AE) and thermal imaging for a selected oil power transformer are presented. The basis for the research, by means of the AE method, was the author’s patented research method. The AE descriptor maps on the side walls of the tested transformer along with the location of areas with increased AE activity and an analysis of the properties of AE signals recorded at the measurement points located in these areas have been performed. The results showed no partial discharges that could threaten further operation of the tested transformer as well as three areas where increased magnetoacoustic emission occurred. Thermal imaging studies were carried out in the 7.5 μm < λ < 13 μm band. Three areas were located on the calculated thermograms: the entire upper surface of the transformer tank and two areas on the side walls of the tested transformer in which increased IR radiation occurr... [more]

Buildings are one of the primary consumers of energy. In addition to the electricity grids, renewable energies can be used to supply the energy demand of buildings. Intelligent systems such as the Internet of Things (IoT) and wireless sensor technologies can also be applied to manage the energy consumption in buildings. Fortunately, integrating renewable energies with these intelligent systems enables creating nearly zero-energy buildings. In this paper, we present the results of our experimentation to demonstrate forming such a building and showing the benefits for building users and the society. We create a system by integrating photovoltaic (PV) technology with an IoT-based control mechanism to supply and consume energy. We further illustrate “how the integration of IoT and PV technology can bring added value to the users?”. To this end, we evaluate the performance of our system against conventional ways of energy supply and consumption for a lighting use case in a dairy store. We a... [more]

Complex relations exist between issues of poverty, responsibility and just transitions toward reduced household energy use. One proposed transitional instrument is Personal Carbon Accounts (PCAs) which provide equal per capita carbon allowances and increase costs for additional usage. Previously modelled PCAs show that a third of households in poverty must curtail usage or pay more for some of their fuel, hitherto making PCAs ethically and politically untenable. Using the UK’s “Understanding Society” database, average per capita carbon allowances and—using occupancy data—the hypothetical allowance each household would receive within a PCA scheme are calculated. Occupancy levels, equivalised incomes and conversion of expenditure to carbon emissions permit analysis of households emitting more or less carbon compared to their allocation. We demonstrate that households emitting greater than average levels of CO2 do so mainly for lifestyle reasons, irrespective of income. Any calculation of... [more]

Solar photovoltaic (PV) power generation has strong intermittency and volatility due to its high dependence on solar radiation and other meteorological factors. Therefore, the negative impact of grid-connected PV on power systems has become one of the constraints in the development of large scale PV systems. Accurate forecasting of solar power generation and flexible planning and operational measures are of great significance to ensure safe, stable, and economical operation of a system with high penetration of solar generation at transmission and distribution levels. In this paper, studies on the following aspects are reviewed: (1) this paper comprehensively expounds the research on forecasting techniques of PV power generation output. (2) In view of the new challenge brought by the integration of high proportion solar generation to the frequency stability of power grid, this paper analyzes the mechanisms of influence between them and introduces the current technical route of PV power... [more]

Failures of the gas turbine hot components often cause catastrophic consequences. Early fault detection can detect the sign of fault occurrence at an early stage, improve availability and prevent serious incidents of the plant. Monitoring the variation of exhaust gas temperature (EGT) is an effective early fault detection method. Thus, a new gas turbine hot components early fault detection method is developed in this paper. By introducing a priori knowledge and quantum particle swarm optimization (QPSO), the exhaust gas temperature profile continuous distribution model is established with finite EGT measuring data. The method eliminates influences of operating and ambient condition changes and especially the gas swirl effect. The experiment reveals the presented method has higher fault detection sensitivity.

The breakdown of the drill bit or rapid decrease of the rate of penetration during the drilling process results in a delay in the progress of drilling. Scientists and engineers are increasingly focusing on research to extend the bit life and improve the drilling rate. In our work, “in situ” drilling parameters were monitored during the drilling process with the roller cone drill bit IADC 136, diameter 155.57 mm (6 1/8"). After drilling, the bit was thoroughly examined to determine the damage and wear that occurred during drilling. The following modern and standardized investigative methods were used: an analysis of rock materials and an analysis of micro and macrostructure materials of the roller cone bit. Analyses were carried out using optical and electron microscopy, a simultaneous thermal analysis of materials of drill bit, analysis of the chemical composition of materials of drill bit, and a determination of the geomechanical parameters of rock materials. The resulting wear, local... [more]

Decision-making for the condition-based maintenance (CBM) of power transformers is critical to their sustainable operation. Existing research exhibits significant shortcomings; neither group decision-making nor maintenance intention is considered, which does not satisfy the needs of smart grids. Thus, a multivariate assessment system, which includes the consideration of technology, cost-effectiveness, and security, should be created, taking into account current research findings. In order to address the uncertainty of maintenance strategy selection, this paper proposes a maintenance decision-making model composed of cloud and vector space models. The optimal maintenance strategy is selected in a multivariate assessment system. Cloud models allow for the expression of natural language evaluation information and are used to transform qualitative concepts into quantitative expressions. The subjective and objective weights of the evaluation index are derived from the analytic hierarchy pro... [more]

The electric vehicle has become an important development direction of the automobile industry, and the lithium-ion power battery is the main energy source of electric vehicles. The accuracy of state of charge (SOC) estimation directly affects the performance of the vehicle. In this paper, the first order fractional equivalent circuit model of a lithium iron phosphate battery was established. Battery capacity tests with different charging and discharging rates and open circuit voltage tests were carried out under different ambient temperatures. The conversion coefficient of charging and discharging capacity and the simplified open circuit voltage model considering the hysteresis characteristics of the battery were proposed. The parameters of the first order fractional equivalent circuit model were identified by using a particle swarm optimization algorithm with dynamic inertia weight. Finally, the recursive formula of a fractional extended Kalman filter was derived, and the battery SOC... [more]

The forecasted electricity demand in Saudi Arabia may be around 120 GW/year by 2032. As per the latest government announcement, Saudi Arabia is aiming to install 57.5 GW of renewable energy capacity by 2030. In this study, firstly, a wind map is developed based on the historical wind data, recorded over a 39-year period, followed by the development of the geographic information system (GIS)-based multi-criteria decision making (MCDM) model for suitable wind farm site selection for Hijaz, the western region of Saudi Arabia. This region is selected as it has a population density of around 25 per sq. km, the highest in Saudi Arabia. For the model, data from various ecological, environmental, and socioeconomic criteria are considered. Finally, the optimization of the wind farm layout on the identified suitable region of 5.5 km × 4 km is performed using the deep-array wake model, DAWM. The optimized layout has locations for 30 wind turbines of 3 MW rated capacity. This optimization process... [more]

The aim of this paper is to present the real-time implementation and measurements of a reduced switch count in space vector pulse width modulation for three-level neutral point clamped inverters (3L-NPC). We implement space vector pulse width modulation, which uses a prediction algorithm to reduce the number of switches in power transistors (switch count) by up to about 13%. The algorithm applies additional redundant voltage vectors. The method is compute-intensive and was implemented on a dual-core TMS320F28379D digital signal controller. The latest measurements of steady and dynamic states of electric drive, powered by a 3L-NPC inverter using this method, confirmed the possibility of using this method in practical implementation. The implementation and results of the measurements are presented in this paper.

Viscosity losses and high degradation factors have a drastic impact over hydrolyzed polyacrylamides (HPAM) currently injected, impacting the oil recovery negatively. Previous studies have demonstrated that biopolymers are promising candidates in EOR applications due to high thermochemical stability in harsh environments. However, the dynamic behavior of a biopolymer as scleroglucan through sandstone under specific conditions for a heavy oil field with low salinity and high temperature has not yet been reported. This work presents the rock−fluid evaluation of the scleroglucan (SG at 935 mgL−1) and sulfonated polyacrylamide (ATBS at 2500 mgL−1) to enhance oil recovery in high-temperature for heavy oils (212 °F and total dissolved solid of 3800 mgL−1) in synthetic (0.5 Darcy) and representative rock samples (from 2 to 5 Darcy) for a study case of a Colombian heavy oilfield. Dynamic evaluation at reservoir conditions presents a scenario with stable injectivity after 53.6 PV with a minimal... [more]

PV hosting capacity (PVHC) analysis on a distribution system is an attractive technique that emerged in recent years for dealing with the planning tasks on high-penetration PV integration. PVHC uses various system performance indices as judgements to find an available amount of PV installation capacity that can be accommodated on existing distribution system infrastructure without causing any violation. Generally, approaches for PVHC assessments are implemented by iterative power flow calculations with stochastic PV deployments so as to observe the operation impacts for PV installation on distribution systems. Determination of the stochastic PV deployments in most of traditional PVHC analysis methods is automatically carried out by the program that is using random selection. However, a repetitive problem that exists in these traditional methods on the selection of the same PV deployment for a calculation was not previously investigated or discussed; further, underestimation of PVHC res... [more]

A tubular permanent-magnet linear generator is suitable for direct drive wave energy conversion owing to its simple structure, easy maintenance and high efficiency. In this study, a novel Gramme winding tubular permanent-magnet linear generator (GW) is designed to increase power density. First, the structure of the Gramme winding and concentrated winding tubular permanent-magnet linear generator is introduced and the operation principle of the generator is analysed. Second, the initial parameters of GW are determined based on the similar overall dimensions to those of the concentrated winding tubular permanent-magnet linear generator. Third, the air gap flux density, external characteristics, voltage regulation, output power, and loss of the two generators are compared. Finally, the DC load capacities of the two generators are compared based on a three-phase full-control bridge rectifying circuit. The results show that the GW has a higher power density than the latter.

In this study, waste cooking oil (WCO) was used as a feedstock for biodiesel production, where the pretreatment of WCO was performed using mineral acids to reduce the acid value. The response surface methodology (RSM) was used to create an interaction for different operating parameters that affect biodiesel yield. The optimised biodiesel yield was 93% at a reaction temperature of 57.50 °C, catalyst concentration 0.25 w/w, methanol to oil ratio 8.50:1, reaction stirring speed 600 rpm, and a reaction time of 3 h. Physicochemical properties, including lower heating value, density, viscosity, cloud point, and flash point of biodiesel blends, were determined using American Society for Testing and Materials (ASTM) standards. Biodiesel blends B10, B20, B30, B40, and B50 were tested on a compression ignition engine. Engine performance parameters, including brake torque (BT), brake power (BP), brake thermal efficiency (BTE), and brake specific fuel consumption (BSFC) were determined using biodi... [more]

This paper presents laboratory studies based on which a stimulation technology for an oil field located in the Zechstein Main Dolomite was investigated. A large number of oil wells in the Main Dolomite produce significant amounts of reservoir water. Matrix acidizing using conventional acid solutions in such wells has caused a significant increase in water cut, because of their affinity for water. The purpose of this cooperation between the Oil and Gas Institute−NRI and the Brenntag Polska was to develop an acid treatment technology that would not increase the water cut after acidizing treatment in wells where oil production is accompanied by the production of reservoir water. Therefore, a series of tests were performed, including the selection of a suitable viscoelastic surfactant that was sensitive to crude oil. The contact of the gel of the viscoelastic surfactant fluid with crude oil resulted in the reduction of its viscosity The tests described herein include dissolution/dispersion... [more]

SLAM technology is increasingly used to self-locate mobile robots in an unknown environment. One of the methods used in this technology is called scan matching. Increasing evidence is placed on the accuracy and speed of the methods used in terms of navigating mobile robots. The aim of this article is to present a modification to the standard method of Iterative Closest Point (ICP) environment scan matching using the authors’ three original weighting factors based on the error modeling. The presented modification was supported by a simulation study whose aim was not exclusively to check the effect of the factors but also to examine the effect of the number of points in scans on the correct and accurate development of the rotation matrix and the translation vector. The study demonstrated both an increase in the accuracy of ICP results following the implementation of the proposed modification and a noticeable increase in accuracy with an increase in the mapping device’s angular resolution... [more]

In this study, inorganic stannite quaternary Cu2M(M = Ni, Co)SnS4 (CMTS) is explored as a low-cost, earth abundant, environmentally friendly and chemically stable hole transport material (HTM). CMTS nanoparticles were synthesized via a facile and mild solvothermal method and processed into aggregated nanoparticle inks, which were applied in n-i-p perovskite solar cells (PSCs). The results show that Cu2NiSnS4 (CNiTS) is more promising as an HTM than Cu2CoSnS4 (CCoTS), showing efficient charge injection as evidenced by considerable photoluminescence quenching and lower series resistance from Nyquist plots, as well as higher power conversion efficiency (PCE). Moreover, the perovskite layer coated by the CMTS HTM showed superior environmental stability after 200 h light soaking in 50% relative humidity, while organic HTMs suffer from a severe drop in perovskite absorption. Although the obtained PCEs are modest, this study shows that the cost effective and stable inorganic CMTSs are promisi... [more]

Isolated microgrids are microgrids which operate autonomously. This paper presents an isolated microgrid which combines a Hydraulic Turbine Generator (HTG) with a Wind Turbine Generator (WTG) to supply consumers forming a Wind Hydro Isolated Microgrid (WHIM). The WHIM includes a Dump Load (DL) to dissipate the active power excess. The WHIM has been modeled and its operation has been simulated in two modes: Wind-Hydro (WH), where both HTG and WTG supply power, and Wind-Only (WO) mode, where the WTG is the active power supplier and the HTG keeps connected to the grid with null power to generate the grid voltage. In WO, a fast frequency regulation is achieved by means of a controller which commands the DL to consume the WTG power excess. Additionally, the simulation of the mode transition from WO to WH, which is triggered by a system active power deficit in WO mode, is shown. A kick starting system designed to speed up the HTG power production improves the transient from WO to WH mode cha... [more]

Thermochemical processes are considered promising pathways to utilize solar energy for fuel production. Several physico-chemical, kinetic and thermodynamic properties of candidate oxides have been studied, yet their morphological stability during redox cycling under radiative heating is not widely reported. Typically when it is reported, it is for large-scale directly irradiated reactors (~1−10 kWth) aimed at demonstrating high efficiency, or in indirectly irradiated receivers where the sample surface is not exposed directly to extreme radiative fluxes. In this work, we aimed to emulate heat flux conditions expected in larger scale solar simulators, but at a smaller scale where experimentation can be performed relatively rapidly and with ease compared to larger prototype reactors. To do so, we utilized a unique infrared (IR) laser-based heating system with a peak heat flux of 2300 kW/m2 to drive redox cycles of two candidate materials, namely nonstoichiometric CeO2-δ and La0.6Sr0.4MnO3... [more]

Gasification technology is actually one of the most effective ways to produce power and hydrogen from biomass. Solid oxide fuel cells (SOFCs) have proved to be an excellent energy conversion device. They can transform the chemical energy content in the syngas, produced by a gasifier, directly into electrical energy. A steady-state model of a biomass-SOFC was developed using process simulation software, ASPEN Plus (10, AspenTech, Bedford, MA, USA). The objective of this work was to implement a biomass-SOFC system capable of predicting performance under diverse operating conditions. The system is made of a gasification zone, gas cleaning steps, and SOFC. The SOFC modelling was done without external subroutines, unlike most models in the literature, using only the existing ASPEN Plus blocks, making the model simpler and more reliable. The analysis of the syngas composition out of each cleaning step is in accordance with literature data. Then, a sensitivity analysis was carried out on the... [more]

The process of anthracite and its semi-coke combustion in the presence of 5 wt.% (in terms of dry salt) additives of copper salts Cu(NO3)2 and Cu(CH3COO)2 was studied. The activating additives were introduced by an incipient wetness procedure. The ignition and combustion parameters for coal samples were examined in the combustion chamber at the heating medium temperatures (Tg) of 600−800 °C. The composition of the gaseous combustion products was controlled using an on-line gas analyzer. The fuel modification with copper salts was found to reduce the ignition delay time on average, along with a drop in the minimum ignition temperature Tmin by 138−277 °C. With an increase in Tg temperature, a significant reduction in the ignition delay time for the anthracite and semi-coke samples (by a factor of 6.7) was observed. The maximum difference in the ignition delay time between the original and modified samples of anthracite (ΔTi = 5.5 s) and semi-coke (ΔTi = 5.4 s) was recorded at a Tg temper... [more]

Lithium-ion batteries are widely used in the energy field due to their high efficiency and clean characteristics. They provide more possibilities for electric vehicles, drones, and other applications, and they can provide the higher requirements necessary for the reliability of battery pack systems. However, it is easy for a battery pack to be unbalanced because of the dependence between the cells. The unbalanced state will make the degradation process more complex and cause abnormal discharge parameters, which brings challenges in the analysis of the state of health (SOH) of battery packs. In order to study the degradation process in the unbalanced condition, in this study, a degradation test of four different configurations of battery packs was designed and implemented, and the degradation process was primarily studied from the perspective of dependence. First, the degradation characteristics and dependency degree of different configurations of the unbalanced state were discussed. Se... [more]

This paper describes Smiling Earth, a mobile app to increase citizens’ awareness about their own carbon footprint, by integrating energy and transport-related data. The main aim of our work is to explore the ways in which Information and Communication Technologies could help raise awareness and educate and motivate citizens about their actions and their consequences on the environment. Smiling Earth provides feedback to users by visualising data about their daily activities with the aim to motivate citizens to change their behaviour to reduce their CO2 emissions by adopting a healthier lifestyle. The value of the Smiling Earth for individuals, cities and communities is discussed. The feedback from an expert evaluation and how Smiling Earth could contribute to Positive Energy Districts are also discussed.

The inevitable emission of aerosols during pyrolysis can negatively affect the downstream process and even pollute the environment. In this work, the characteristics of aerosols were investigated during corn stalk pyrolysis at 400−900 °C. The effects of other operation conditions on the aerosol emissions were also probed with online and offline instruments. Results show the yield of aerosol presents a regular change with temperature in a wide range ratio of 3.4−8.7 wt.%. The aerosol size distribution reveals a unimodal form mainly in the 1.1−2.1 μm accumulation range and the maximum emission achieved is about 35 mg/g for SR and SP at 500 °C. Nevertheless, SL gives about 34 mg/g at 600 °C. High temperature promotes the decomposition of polymers into partciles with small diameter (less than PM1.0). The microtopography of aerosol presents spherical droplets, elongated-like liquid and solid particles that form heterogenous or homogeneous aggregations, that also happen on account of collisi... [more]

Heat-driven coolers provide a reliable and environmentally benign alternative to traditional electrically powered chillers. Their main advantage is that they can be driven using low enthalpy heat sources. A solar system is installed at the school of Mechanical Engineering of National Technical University of Athens in order to examine the potential of thermal storage and solar cooling under Athens climatic conditions. The cooling effect is produced using a dual bed, single stage, zeolite/water adsorption chiller with cooling capacity of 10 kW at its nominal conditions of operation. Both vacuum tube collectors and hybrid photovoltaic thermal collectors are installed in order to supply the system with heat. The system is evaluated in terms of solar collectors’ useful energy production, heat stored in the intermediate buffer and cooling system’s performance. It is observed that the cooling system operates satisfactorily under Athens climatic conditions achieving a maximum cooling capacity... [more]