Given the substantial energy use for space cooling in buildings, integrating energy-efficient and sustainable cooling systems into buildings has become increasingly more important. Even though the cooling potential of a near-surface earth-to-air heat exchanger (EAHE) with grass cover was demonstrated in previous studies, the energy savings and environmental benefits resulting from using the EAHE have not yet been quantified. Therefore, in this study, we quantify the energy savings resulting from using a near-surface earth-to-air heat exchanger (EAHE) with grass-covered ground as a precooling unit in hot desert climates. The outlet air conditions of the EAHE during 9 months of the year (March to November), where space cooling is required, are predicted using a 3D transient CFD model, which is validated against field measurements. The EAHE is fabricated from a 1 mm thick aluminum tube with a diameter of 0.15 m and a length of 21.5 m, buried 0.4 m deep. The results showed that the EAHE ca... [more]

The decentralization in the electrical power grids has gained increasing importance, especially in the last two decades, since transmission system operators (TSO), distribution system operators (DSO) and consumers are more aware of energy efficiency and energy sustainability issues. Therefore, globally, due to the introduction of energy production technologies near the consumers, in residential and industrial sectors, new scenarios of distributed energy resources (DER) are emerging. In order to guarantee an adequate power management in the electrical power grids, incorporating producers, consumers and producers-consumers (prosumers) together, it is important to adopt intelligent systems and platforms that allow the provision of information on energy consumption and production in real time, as well as for obtaining a fair price for the sale and purchase of energy. In this paper, we analyze the literature to identify the appropriate solutions to implement a decentralized electrical power... [more]

In our recent papers, it was shown that the thermal nanocrystallization of glassy analogs of selected cathode materials led to a substantial increase in electrical conductivity. The advantage of this technique is the lack of carbon additive during synthesis. In this paper, the electrochemical performance of nanocrystalline LiFePO4 (LFP) and LiFe0.88V0.08PO4 (LFVP) cathode materials was studied and compared with commercially purchased high-performance LiFePO4 (C-LFP). The structure of the nanocrystalline materials was confirmed using X-ray diffractometry. The laboratory cells were tested at a wide variety of loads ranging from 0.1 to 3 C-rate. Their performance is discussed with reference to their microstructure and electrical conductivity. LFP exhibited a modest electrochemical performance, while the gravimetric capacity of LFVP reached ca. 100 mAh/g. This value is lower than the theoretical capacity, probably due to the residual glassy matrix in which the nanocrystallites are embedded... [more]

This study provides a workflow and preliminary estimations of the estimated ultimate recovery (EUR) volumes for natural gas and condensate liquids in the Tuwaiq Mountain Formation, the principal target in the Jafurah Field development project in Saudi Arabia. The strategic need for the field development is reviewed and the field characteristics are outlined based on public data sources complemented with data from analogous reservoirs. The target zone in the Jafurah Basin is a carbonaceous shale, being developed with up to 10,000-ft-long multistage-fractured laterals with 30 ft perforation cluster spacing and an assumed typical 1250 ft well spacing. The field will come on stream in 2024, when the gas-gathering pipeline system, natural gas processing plant, and underground gas storage facilities will all be in place. The range of uncertainties in the key reservoir parameters is taken into account to estimate preliminary EUR volumes (P90, P50, and P10) for both gas and condensates. Based... [more]

In the face of increasing demands with regard to the share of renewable energy sources in the energy mix, adsorption chillers are becoming a potentially important part of the energy transition. A key component of this type of equipment is the heat exchanger in the adsorption bed, the design of which affects both heat and mass transfer. This study includes an analysis of the geometry and materials used to manufacture such heat exchangers. The geometry analysis is mainly based on the evaluation of the impact of the different dimensions of the exchanger components on heat and mass transfer in the bed. The second part of the study focuses on material-related issues where the main emphasis is on the analysis of the thermal inertia of the exchanger. The paper analyses the latest research on the design of exchangers in adsorption beds, mainly from 2015−2021. Currently, the commonly used SCP and COP coefficients and various test conditions do not provide sufficient information for comparative... [more]

The timeliness of the complex automated diagnostics of the metal condition for all characteristics has been substantiated. An algorithm for the automation of metallographic quality control of metals is proposed and described. It is based on the use of neural networks for recognizing images of metal microstructures and a precedent method for determining the metal grade. An approach to preliminarily process the images of metal microstructures is described. The structure of a neural network has been developed to determine the quantitative characteristics of metals. The results of the functioning of neural networks for determining the quantitative characteristics of metals are presented. The high accuracy of determining the characteristics of metals using neural networks is shown. Software has been developed for the automated recognition of images of metal microstructures, and for the determination of the metal grade. Comparative results of carrying out metallographic analysis with the dev... [more]

For autonomous driving research, using a scaled vehicle platform is a viable alternative compared to a full-scale vehicle. However, using embedded solutions such as small robotic platforms with differential driving or radio-controlled (RC) car-based platforms can be limiting on, for example, sensor package restrictions or computing challenges. Furthermore, for a given controller, specialized expertise and abilities are necessary. To address such problems, this paper proposes a feasible solution, the Ridon vehicle, which is a spacious ride-on automobile with high-driving electric power and a custom-designed drive-by-wire system powered by a full-scale machine-learning-ready computer. The major objective of this paper is to provide a thorough and appropriate method for constructing a cost-effective platform with a drive-by-wire system and sensor packages so that machine-learning-based algorithms can be tested and deployed on a scaled vehicle. The proposed platform employs a modular and h... [more]

Developing energy from renewable sources and modernizing the energy system are critical components of China’s efforts to combat climate change. Policymakers and authorities have made significant attempts to bring them. However, one of the major impediments to China’s energy revolution is financial limitations, which are inextricably linked to the country’s economic growth. The present research paper intends to investigate the relationship between economic growth and sustainable financial development on the use of energy from renewable sources in both the short and long run in the context of China. To achieve this, the researchers have utilized the panel data consisting of 10 years from 2011 to 2020. When compared to cross-sectional and time-series data samples, the panel data model offers many benefits. For starters, the panel data includes information on the passage of time and the cross-sectional area. Another benefit of using panel-data models with a larger degree of freedom is that... [more]

In recent decades, due to the increase in the capabilities of microprocessors and the advent of graphics processing units (GPUs), the use of machine learning methodologies has become popular in many fields of science and technology [...]

In Generation Expansion Planning (GEP), the power plants lifetime is one of the most important factors which to the best knowledge of the authors, has not been investigated in the literature. In this article, the power plants lifetime effect on GEP is investigated. In addition, the deep learning-based approaches are widely used for time series forecasting. Therefore, a new version of Long short-term memory (LSTM) networks known as Bi-directional LSTM (BLSTM) networks are used in this paper to forecast annual peak load of the power system. For carbon emissions, the cost of carbon is considered as the penalty of pollution in the objective function. The proposed approach is evaluated by a test network and then applied to Iran power system as a large-scale grid. The simulations by GAMS (General Algebraic Modeling System, Washington, DC, USA) software show that due to consideration of lifetime as a constraint, the total cost of the GEP problem decreases by 5.28% and 7.9% for the test system... [more]

Interior permanent magnet (IPM) machines with hairpin windings have attracted significant attention in EV applications owing to their low DC resistance and excellent thermal capabilities. In this paper, we present a comprehensive investigation of AC winding losses in IPM machines for traction applications, including analytical modeling, the influence of design parameters, and finite element (FE) verification. The proposed analytical model can predict the trends in AC winding losses for any number of bar conductors and slot/pole combinations. The results of the parametric study, obtained via the analytical model, are presented to examine the effects of key design parameters, such as conductor width and height, phase arrangement, and slot-per-pole-per-phase (SPP). To incorporate more practical issues into the analysis of IPM machines with hairpin windings, extensive FE simulations were conducted. The results indicated that the AC winding losses decrease with an increasing number of condu... [more]

This paper presents the performance analysis of a latest-generation hybrid vehicle (Toyota Yaris 2020) with a testing campaign in real road conditions and a comparison with the previous model (Toyota Yaris 2017). The study was conducted by applying the Real Drive Truth Test protocol, developed by the research group, validated and spread to other full hybrid vehicles: Toyota Prius IV (2016) and Toyota Yaris 2017 (2017). In the case of the 2020 tests, the co-presence on board—deemed unsafe in the usual ways given the ongoing pandemic—was achieved through precise and sophisticated remote control. An on-board diagnostic computer, video transmission and recording equipment guarantee the virtual co-presence of a technical control room and a driver. Thus, several engineers can follow and monitor each vehicle via a 4G modem (installed in each vehicle), analysing data, route and driver behaviour in real-time, and therefore even in the presence of a single occupant in the car under test. The utm... [more]

Piezoelectric-based nano resonators are smart structures that can be used for mechanical sensors and actuators in miniature systems. In this study, the nonlinear vibration behavior of a curved piezoelectric-layered nanotube resonator was investigated. The curved structure comprises a core nanotube and a slender layer of piezoelectric material covering the inner nanotube where a harmonic voltage is applied to the piezoelectric layer. Applying the energy method and Hamiltonian principle in association with non-local theories, the governing equations of motion of the targeted system are obtained. Then, the problem is solved using the Galerkin and multiple scales methods, and the system responses under external excitation and parametric load are found. Various resonance conditions are investigated including primary and parametric resonances, and the frequency responses are obtained considering steady state motions. The effects of different parameters such as applied voltage, piezoelectric... [more]

The advent of the new millennium, with the promises of the digital age and space technology, favors humankind in every perspective. The technology provides us with electric power and has infinite use in multiple electronic accessories. The electric power produced by different sources is distributed to consumers by the transmission line and grid stations. During the electric transmission from primary sources, there are various methods by which to commit energy theft. Energy theft is a universal electric problem in many countries, with a possible loss of billions of dollars for electric companies. This energy contention is deep rooted, having so many root causes and rugged solutions of a technical nature. Advanced Metering Infrastructure (AMI) is introduced with no adequate results to control and minimize electric theft. Until now, so many techniques have been applied to overcome this grave problem of electric power theft. Many researchers nowadays use machine learning algorithms, trying... [more]

The challenge of maintaining the required level of mobility and air quality in cities can be met by deploying an appropriate management system in which the immediate vicinity of roads is monitored to identify potential pollution hotspots. This paper presents an integrated low-cost system which can be used to study the impact of traffic related emission on air quality at intersections. The system was used for three months in 2017 at five locations covering intersections in the centre of a mid-sized city. Depending on the location, pollution hotspots with high PM2.5 and PM10 concentrations occurred 5−10% of the time. It was shown that despite the close mutual proximity of the locations, traffic and the immediate surroundings lead to significant variation in air quality. At locations with adverse ventilation conditions a tendency towards more frequent occurrences of moderate and sufficient air quality was observed than at other locations (even those with more traffic). Based on the result... [more]

Cattle biomass (CB or manure from cattle) is proposed as reburn fuel under slightly fuel-rich conditions. The CB includes wastes from cattle feedlots (cattle grown in feedlots to slaughter weights of 450−640 kg) termed as Feedlot Biomass (FB) and cattle wastes from dairy farms termed as Dairy Biomass (DB). NOx emissions from coal-fired power plants can be reduced by using pure CB and Coal:CB mixtures as reburn fuels (10~30% by heat) injected after the primary combustion region. Experiments with Coal:CB mixtures as reburn fuels were performed using the 30 kW burner facility. Part I deals with results from experiments using pure FB and Coal:FB blends as reburn fuels while Part II presents results on extent of NOx reduction using pure DB and Coal:DB blends as reburn fuels (RF). In the current work, results on NOx emission are presented with FB and Coal:FB blends as RF. The parametric studies include: equivalence ratio in reburn zone (ERRBZ), vitiated air, angle of reburn nozzles, presence... [more]

For a few years the multi-physics modelling of the resonance cavity (resonator) of MW-class continuous-wave gyrotrons, to be employed for electron cyclotron heating and current drive in magnetic confinement fusion machines, has gained increasing interest. The rising target power of the gyrotrons, which drives progressively higher Ohmic losses to be removed from the resonator, together with the need for limiting the resonator deformation as much as possible, has put more emphasis on the thermal-hydraulic and thermo-mechanic modeling of the cavity. To cope with that, a multi-physics simulator has been developed in recent years in a shared effort between several European institutions (the Karlsruher Institut für Technologie and Politecnico di Torino, supported by Fusion for Energy). In this paper the current status of the tool calibration and validation is addressed, aiming at highlighting where any direct or indirect comparisons with experimental data are missing and suggesting a possibl... [more]

The development of cooperative control strategies for microgrids has become an area of increasing research interest in recent years, often a result of advances in other areas of control theory such as multi-agent systems and enabled by rapid advances in wireless communications technology and power electronics. Though the basic concept of cooperative action in microgrids is intuitively well-understood, a comprehensive survey of this approach with respect to its limitations and wide range of potential applications has not yet been provided. The objective of this paper is to provide a broad overview of cooperative control theory as applied to microgrids, introduce other possible applications not previously described, and discuss recent advances and open problems in this area of microgrid research.

This paper describes the matching of various loads to sources (including nonlinear ones). The purpose of matching is to extract the maximum available power from the source. This has particular importance for renewable sources and energy-harvesting devices, in which unused energy is just wasted. The main innovations in this paper include (and followed by examples) simplified calculation of the matching parameter for a controllable load and matching by means of a family of power-conservative two-port networks, denoted POPI (Pin = Pout), such as transformers, gyrators, loss-free resistors (LFRs) and series LFRs (SLFRs). An additional innovation described in this paper is a new, simplified model of an HF power amplifier based on the series LFR concept. This model predicts that the efficiency of the HF power amplifier operated under the matched-mode condition can significantly exceed the 50% efficiency limit that is predicted by the conventional model. As HF power amplifiers drive antennas... [more]

CO2 storage is a greenhouse gas mitigation instrument for many countries. In this paper, we investigate the possibility of CO2 storage in the region of the Precaspian basin using the compositional flow model that was verified by the data of the Frio pilot project, USA. We use local grid refinement in the commercial reservoir simulator. In the reservoir simulation for data of the Frio Pilot project, we have achieved a good history matching of well pressure. Different scenarios were tested, and post-injection migration was shown for both case studies. The long-term reservoir simulation shows the potential amount of trapped CO2 by residual and dissolved trapping mechanisms in the Precaspian basin. The performed uncertainty study covered the uncertainty of the model’s parameters resulting in P10, P50 and P90 cases in terms of the amount of trapped CO2.

As the proportion of power generation using renewable energy increases, it is important to improve the operational flexibility of gas turbines (GTs) for the stability of power grids. Increasing the ramp-rate of GTs is a general solution. However, a higher ramp-rate increases the turbine inlet temperature (TIT), its rate of change, and the fluctuation of the frequency of produced electricity, which are negative side effects. This study proposes a method to optimize the set-point schedule for a PID controller to improve the ramp-rate while decreasing the negative impacts. The set-point schedule was optimized for a 170-MW class GT using a genetic algorithm to minimize the difference between the value of the process variable and the set-point value of the conventional control. The advanced control reduced the fluctuation of the rotation speed by 20% at the reference ramp-rates (12 MW/min and 15 MW/min). The maximum TIT decreased by 6.3 °C, and its maximum rate of change decreased from 0.7... [more]

Nuclear energy is an option that enables a significant reduction of greenhouse gases emissions at the national and European Union (EU) level. However, it is also an option that is mostly influenced by public opinion and an option that has strong cross-border impact. Croatia does not consider nuclear options, but a possible future turn to nuclear might have an influence on other EU countries. The possibility for such a turn is analyzed, taking into account public opinion as well as historical and economic factors. Based on the results of a public opinion survey, it can be deduced that the Croatian public is not inclined to nuclear energy and considers it a risky option, although nuclear power plants in neighboring countries are not perceived as a high-risk threat. Trust in government as an information source is very low. Despite historical aspects that suggest scientific and expert knowledge capable of handling nuclear build, public opinion and the low economic framework indicate that a... [more]

Strategic selection of glazing, its window-to-wall ratio, and wall thickness of building reduce the energy consumption in the built environment. This paper presents the experimental results of solar optical properties of five glasses: clear, tinted bronze, tinted green, bronze reflective, and polymer dispersed liquid crystal glasses. Laterite room models were modeled with four different thicknesses and four different glasses using Design Builder, and thermal simulation tests were carried out using Energy Plus. The energy savings and carbon emission mitigation prospective of a building’s glazing variety, window-to-wall ratio (WWR), and wall thickness were investigated. The results revealed that among the five window glasses studied, the polymer dispersed liquid crystal glazing window (PDLCGW) was found to be the most energy-efficient for low heat gain in laterite rooms. The laterite room with 0.23 m wall thickness and 40% PDLCGW WWR reduced 18.9% heat gain in comparison with the laterit... [more]

This research article explores the behavior of a phase change material (PCM) when it undergoes interrupted melting and freezing, through experimental investigations using a heat flow meter apparatus. A fatty acid-based organic PCM, encapsulated within polyethylene and thin aluminum foil layers, was experimentally tested in this study. Experiments were designed to represent multiple interrupted phase change scenarios that could occur within PCMs applied in buildings. The experimental results were analyzed and compared with previously reported assumptions in numerical models dealing with PCM hysteresis and interrupted phase change processes. These comparisons indicated that the assumptions used in the different numerical models considered can capture the interrupted phase change phenomena with varying degrees of accuracy. The findings also highlighted the need for additional experimental research on different phase change processes that can occur in building applications of PCMs.

High-temperature desulfurization techniques are fundamental for the development of reliable and efficient conversion systems of low-cost fuels and biomass that answer to the nowadays environmental and energy security issues. This is particularly true for biomass gasification coupled to SOFC systems where the sulfur content has to be minimized before being fed to the SOFC. Thus, commercially available zinc oxide has been studied and characterized as a desulfurizing agent in a fixed-bed reactor at high temperatures from 400 °C to 600 °C. The sorbent material was characterized by XRD, BET, SEM, and EDS analyses before and after adsorption. The sorbent’s sorption capacity has been evaluated at different temperatures, as well as the breakthrough curves. Moreover, the kinetic parameters as the initial sorption rate constant k0, the deactivation rate constant kd, and the activation energy have been calculated using the linearized deactivation model. The best performances have been obtained at... [more]