Geothermal heating is considered to be one of the low-carbon-energy technologies for building heating. Aiming at the problem that the operating cost and investment cost of geothermal heating systems are still high, the conventional geothermal heating system coupled with energy storage for office building heating is studied in this paper. Four operational strategy models of the coupled system are established based on time-of-use electricity prices. A genetic algorithm is used to find the optimal value of each decision variable using minimization of levelized cost of heat (LCOH) as the objective function. The influences of electricity and equipment prices on the optimal values of the decision variables are discussed. Four operation strategies are investigated. If only operating cost is considered in the optimization, comparison shows that the best operation strategy is the one giving high priority to use the energy storage tank for heating during the peak electricity period. However, if... [more]

The operation of coal mines is intricately linked with emitting a large quantity of coal mine methane, and in most cases, this methane releases into the atmosphere. In total, according to statistics, coal mining enterprises emit 8% of anthropogenic methane, determining a contribution to greenhouse gas emissions to the amount of 17%. There are various means for coal mine methane utilization. In this study, the concept “Coal-Energy-Information” is proposed. This concept implies both the construction of data processing centers on the industrial sites of coal mines and the usage of coal mine methane. Coal mine methane can be used as a primary energy source for the energy supply of data processing center consumers as well as coal mine consumers with necessary energy resources (electricity, heat, and cooling). Within the framework of the proposed concept, three options of coal mine methane utilization are considered. The first option is the use of gas genset for electrical and thermal energy... [more]

A power conversion system needs high efficiency for modern-day applications. A DC−DC isolated bidirectional dual active bridge-based converter promises high efficiency and reliability. There are several converter topologies available in the market claiming to be the best of their type, so it is essential to choose from them based on the best possible result for operation in a variety of applications. As a result, this article examines the characteristics, functionality, and benefits of dual active bridge-based DC−DC converter topologies and the other members of the family, as well as their limits and future advances. A high-frequency transformer is also an important device that is popular due to high leakage inductance in dual active bridge (DAB) converters. Therefore, a detailed review is presented, and after critical analysis, minimized leakage inductance in the toroidal transformer is obtained using the ANSYS Maxwell platform. Furthermore, this work includes a comprehensive examinat... [more]

Accurate surge pressure prediction during tripping is significant to ensure drilling safety. Based on the theory of wellbore hydraulics and heat transfer, a surge pressure prediction model considering the influence of HTHP and joints is established in this paper. The finite difference method is used to solve the wellbore flow model. Compared with the measured surge pressure, it was found that the error between the predicted and measured values after considering the above factors was only 0.89%. The influence of dimensionless joint outer diameter, joint length and drill string tripping speed on the surge pressure was further analyzed. The results show that the existence of joints increases the surge pressure. When the dimensionless joint outer diameter was increased from 0.70 to 0.91, the surge pressure increased by 76%. Neglecting the effect of the joint will cause a large error in calculating the surge pressure. In addition, the surge pressure is positively correlated with the drill s... [more]

This paper introduces a phase one computational design analysis study of a hydrokinetic horizontal parallel stream direct-drive (no gear box) counter-rotating Darrieus turbine system. This system consists of two Darrieus rotors that are arranged in parallel and horizontal to the water stream and operate in counter-rotation due to the incoming flow. One of the rotors directly drives an armature coil rotor and the other one a permanent magnet generator. A two-dimensional (2-D) and three-dimensional (3-D) computational fluid dynamic (CFD) simulation study was conducted to assess the hydrokinetic performance of the design. From a high computational cost and time perspective, the simulation setup was reduced from a 3-D to a 2-D analysis. Although useful information was obtained from the 3-D simulations, the output performance could be assessed with the 2-D simulations without compromising the integrity of the turbine output results. A scaled experimental design prototype was developed for s... [more]

Currently, solar energy is one of the leading renewable energy sources that help support energy transition into decarbonized energy systems for a safer future. This work provides a comprehensive review of mathematical modeling used to simulate the performance of photovoltaic (PV) modules. The meteorological parameters that influence the performance of PV modules are also presented. Various deterministic and probabilistic mathematical modeling methodologies have been investigated. Moreover, the metaheuristic methods used in the parameter extraction of diode models of the PV equivalent circuits are addressed in this article to encourage the adoption of algorithms that can predict the parameters with the highest precision possible. With the significant increase in the computational power of workstations and personal computers, soft computing algorithms are expected to attract more attention and dominate other algorithms. The different error expressions used in formulating objective functi... [more]

The textile industry accounts for approximately 2% of global greenhouse gas emissions. There is a significant opportunity to decarbonize the textile industry by electrification of process heating where low- or zero-carbon electricity is used. Electrified process heating can be achieved through cross-cutting technologies without modifying the textile process equipment and/or through replacing the existing equipment with technologies that employ electromagnetic or resistance heating techniques for specific end-use applications. This paper aims to investigate the potential for electrification of process heating in the textile wet-processing industry in three of the top textile-producing and exporting regions in the world. To do this, two separate technology pathways, i.e., electrification through (a) industrial heat pumps and (b) textile end-use processes are developed and analyzed. The results show that the total potential final energy and CO2 savings due to electrification in both scena... [more]

To reduce the on-peak electrical power consumption, storage devices are widely performed with the help of an energy management system. According to IEA, residential air conditioning consumes 70% of the electricity, increasing by 4% every year. To minimize peak power consumption, thermal energy storage (TES) can be used to store cooled water for the air conditioning system. An efficient chilled water tank was designed and computationally investigated. Three-dimensional cylindrical tanks were simulated with seven different heights to diameter (H:D) ratios. At first, the temperature changes in a chilled water tank during discharging and charging periods were studied. An 11-h charging period was carried out during the off-peak time at night, while the discharging period was 13 h during the daytime. Under time constraints regarding peak and off-peak periods, a tank with an H:D = 2.0 can only be used for 13-h discharging. Then the chilled water was simulated with a set temperature of 4 °C du... [more]

This review paper looks briefly at conventional approaches and examines the intelligent means for fault diagnosis (FD) and condition monitoring (CM) of electrical drives in detail, especially the ones that are common in Industry 4.0. After giving an overview on fault statistics, standard methods for the FD and CM of rotating machines are first visited, and then its orientation towards intelligent approaches is discussed. Major diagnostic procedures are addressed in detail together with their advancements to date. In particular, the emphasis is given to motor current signature analysis (MCSA) and digital signal processing techniques (DSPTs) mostly used for feature engineering. Consequently, the statistical procedures and machine learning techniques (stemming from artificial intelligence—AI) are also visited to describe how FD is carried out in various systems. The effectiveness of the amalgamation of the model, signal, and data-based techniques for the FD and CM of inductions motors (IM... [more]

Motor vehicles are the backbone of global transport. In recent years, due to the rising costs of fossil fuels and increasing concerns about their negative impact on the natural environment, the development of low-emission power supply systems for vehicles has been observed. In order to create a stable and safe global transport system, an important issue seems to be the diversification of propulsion systems for vehicles, which can be achieved through the simultaneous development of conventional internal combustion vehicles, electric vehicles (both battery and fuel cell powered) as well as combustion hydrogen-powered vehicles. This publication presents an overview of commercial vehicles (available on the market) powered by internal combustion hydrogen engines. The work focuses on presenting the development of technology from the point of view of introducing ready-made hydrogen-powered vehicles to the market or technical solutions enabling the use of hydrogen mixtures in internal combusti... [more]

Renewable Energy Communities (RECs) have been defined as modes of collective prosumership under the Renewable Energy Directive (RED II). We evaluate the benefits offered by RECs and the barriers and enablers impacting their uptake. Germany is taken as a case study for a novel multi-disciplinary assessment of a potential REC intended as a climate-neutral, mixed-use district. We found that energy cooperatives may not be suited to form RECs, but the future may see an uptake of innovative organizational structures such as the Consumer Stock Ownership Plan. It has been shown that a high degree of prosumership can provide technical and economic benefits with maximum greenhouse gas savings of 35% and a maximum self-consumption share of 61% compared to no prosumership. The REC has a negative Net Present Value (NPV) after 25 years of operation and lacks financial attractiveness. A positive NPV is only possible by using the cost savings from prosumership to recoup the investments faster. RECs ar... [more]

Photovoltaics and wind power are expected to account for a large share of power generation in the carbon-neutral era. A gas turbine combined cycle (GTCC) with an industrial gas turbine as the main engine has the ability to rapidly start up and can follow up to load fluctuations to smooth out fluctuations in power generation from renewable energy sources. Simultaneously, the system must be more efficient than today’s state-of-the-art GTCCs because it will use either Carbon dioxide Capture and Storage (CCS) when burning natural gas or hydrogen/ammonia as fuel, which is more expensive than natural gas. This paper describes the trend of cooled turbine rotor blades used in large industrial gas turbines that are carbon neutral. First, the evolution of cooled turbine stationary vanes and rotor blades is traced. Then, the current status of heat transfer technology, blade material technology, and thermal barrier coating technology that will lead to the realization of future ultra-high-temperatu... [more]

Compared with traditional injection tubular strings, the stresses on CO2 injection tubular strings are more complex. The results from field applications show that the phase transition of CO2 fluid in CO2 injection strings is an important factor in the calculation of temperature distribution and analysis of string mechanics. Therefore, we propose a strength analysis method for CO2 injection tubular strings that considers the CO2 phase transition. We selected four CO2 injection strings in an oil field in China as examples to evaluate their strength and safety. First, we established coupled differential equations for the temperature, pressure, and physical parameters of CO2 injection strings according to the theory of fluid flow and heat transfer. Then, we used an adaptive fuzzy neural network to construct the model for calculating the CO2 convection heat transfer coefficient and used this to obtain the high-precision convection heat transfer coefficients of tubular strings under conditio... [more]

The existing recycling methods of PHA-based material are ineffective in terms of increasing resource efficiency and the production of high value end-of-life products. Therefore, in this study, a novel approach of acidogenic fermentation was proposed to recycle PHB-based composites reinforced with natural fibers such as cellulose, chitin, chitosan, orange waste, sawdust, soy protein, and starch. The inclusion of cellulose, chitosan, and sawdust improved the impact properties of the composites while other fillers had various effects on the mechanical properties. These three composites and neat PHB were subsequently subjected to biological degradation via acidogenic digestion to determine the possibility of converting PHB-based composites into volatile fatty acids (VFAs). Two different pH levels of 6 and 10 were applied to assess the effect of pH on the bioconversion and inhibition of the methanogenesis. The results showed promising PHB degradation, contributing to considerable VFA produc... [more]

An automated drilling system requires a real-time evaluation of the drilling bit during drilling to optimize operation and determine when to stop drilling and switch bits. Furthermore, in the dynamic modeling of drill strings, it is necessary to take into account the interactions between drilling bits and rock. To address this challenge, a hybrid approach that combines physics-based models with data analytics has been developed to handle downhole drilling measurements in real time. First, experimental findings were used to formulate mathematical models of cutter−rock interaction in accordance with their geometrical characteristics, rock properties, and drilling parameters. Specifically, these models represent the normal and contact forces of polycrystalline diamond compact cutters (PDCs). Experimental data are analyzed utilizing deep learning, nonlinear regression, and genetic algorithms to fit nonlinear equations to data points. Following this, the recursive least square was implement... [more]

In developing countries, many areas are deprived of electrical energy. Access to cleaner, more affordable energy is critical for improving the poor’s living conditions in developing countries. With the advent of smart grid technology, the integration and coordination of small grids, known as nanogrids, has become very easy. The purpose of this research is to propose a nanogrid model that will serve the purpose of providing the facility of electrical power to the poor rural community in Pakistan using hybrid renewable energy sources. This paper targets the electrification of a poor rural community of Akora Khatak, a small district located in Pakistan. The mathematical modeling of solar and wind energy, neural network-based forecasting of solar irradiance and wind velocity, and the social analysis to calculate the payback period for the community have been discussed in this paper.

With a proliferation of diverse types of renewable distributed generation (DG) into the distribution network, an equivalent model of an active distribution network (ADN) is extremely important, since the detailed modeling of the whole ADN is much more complex and time consuming. However, different studies developed different model structures of ADNs, which are difficult to be applied in a power system simulation. At the same time, the DG’s low voltage ride through the (LVRT) control was not considered in the existing ADN model, which may lead to a large modelling error. In this paper, a general equivalent model is developed for the ADN with a significant amount of DGs, based on a two-step modelling method. Step one, motivated by the dynamic similarities between the doubly-fed induction generator (DFIG)-based wind turbines, direct drive permanent magnet synchronous generator (DDPMSG)-based wind turbines, and photovoltaic (PV) generation, a general model structure of a renewable DG is in... [more]

In this study, a newly established bench-scale thermophilic continuously stirred fluidized bed reactor (CSFBR) was applied for anaerobic co-digestion of food waste (FW) with grease trap waste (GTW). The performance of CSFBR regarding stability and treatment efficiency was inspected through a laboratory contrast experiment with two traditional continuous stirred tank reactors (CSTRs). In the OLR range of 3.19−7.41 g COD/L/d, the methane production rate of the thermophilic CSFBR was about as high as that of the thermophilic CSTR. Nevertheless, the thermophilic CSFBR had much lower VFAs (<1000 mg/L) and LCFA concentrations (<100 mg/L) as compared with the thermophilic CSTR. Unlike the mesophilic CSTR, there was no foaming that occurred in the CSFBR during the whole experimental period. The results all suggested that CSFBR simultaneously provided high treatment capacity and process stability in anaerobic digestion with high-lipid loading.

Spatial separation into acidogenic and methanogenic stages is considered a viable option to ensure process stability, energy efficiency and the better control of key anaerobic digestion (AD) parameters. The elucidation of the optimal modes of two-stage AD for the maximization of the recovery of biofuels (H2 and CH4) is still an urgent task, the main optimization criteria being the highest energy yield (EY) and energy production rate (EPR). In this work, a response surface methodology was used for an optimization of energy production from the two-stage mesophilic−thermophilic AD of cheese whey (CW). Three dilution rates of CW, providing values of 10.9, 14.53 and 21.8 g for the chemical oxygen demand (COD)/L in the influent and three hydraulic retention times (HRTs) (1, 2 and 3 days) in methanogenic biofilters at a constant HRT in an acidogenic biofilter of 0.42 days, were tested to optimize the EY and EPR. The desirability approach produced combined optimum conditions as follows: the di... [more]

With economic growth and rising incomes, increasing consumption of fossil energy is leading to environmental pollution and climate change, which requires increased innovative inputs to promote the efficiency of renewable energy use. Considering the important impact of innovation input and climate change on renewable energy consumption, greenhouse gas emissions, and green economic growth, this study uses simultaneous equation and sys-GMM model to explore the dynamic nexus of innovation input, climate change, and energy-environment-growth in OECD and non-OECD countries, with panel data covering 2000 to 2019. The empirical results show that renewable energy consumption in non-OECD countries significantly promoted green economic growth, while OECD countries did the opposite. Moreover, renewable energy consumption significantly reduces greenhouse gas emissions caused by climate change, especially for OECD countries. When the level of economic growth exceeds a certain inflection point, green... [more]

Climate change is exacerbated by vehicle emissions. Furthermore, vehicle pollution contributes to respiratory and cardiopulmonary diseases, as well as lung cancer. This requires a drastic reduction in global greenhouse gas emissions for the automobile industry. To address this issue, researchers are required to reduce friction, which is one of the most important aspects of improving the efficiency of internal combustion engines. One of the most important parts of an engine that contributes to friction is the piston ring cylinder liner (PRCL) coupling. Controlling the linear deformation enhances the performance of the engine and, as a result, contributes positively to its performance. The majority of the tests to study the conformability between cylinder liner and piston were carried out on cylinder liners made of cast iron. It is possible to improve the performance of piston ring cylinder liner couplings by implementing new and advanced manufacturing techniques. In this work, a validat... [more]

Cloud covering is an important factor affecting solar radiation and causes fluctuations in solar energy production. Therefore, real-time recognition and the prediction of cloud covering and the adjustment of the angle of photovoltaic panels to improve power generation are important research areas in the field of photovoltaic power generation. In this study, several methods, namely, the principle of depth camera measurement distance, semantic segmentation algorithm, and long- and short-term memory (LSTM) network were combined for cloud observation. The semantic segmentation algorithm was applied to identify and extract the cloud contour lines, determine the feature points, and calculate the cloud heights and geographic locations of the cloud shadows. The LSTM algorithm was used to predict the trajectory and speed of the cloud movement, achieve accurate and real-time detection, and track the clouds and the sun. Based on the results of these methods, the shadow area of the cloud on the gr... [more]

The present study utilizes a density-based topology optimization method to design a serpentine channel under turbulent flow, solving a high pressure loss issue and enhancing heat transfer capability. In the topology optimization, the k−ε turbulence model is modified by adding penalization terms to reveal turbulence effects. Heat transfer modeling is included by setting the modified energy equation with additional terms related to topology optimization. The main objective is to minimize pressure loss while restricting heat transfer. The 2D simplified model is topologically optimized. Then, the optimal solution with intermediate results is extruded in the 3D system and interpreted with triply periodic minimal surfaces (TPMS) to further enhance heat transfer performance. Compared to the baseline serpentine channel, the optimized model infilled with the diamond-TPMS structure lowers pressure loss by 30.8% and significantly enhances total heat transfer by up to 45.8%, yielding thermal perfo... [more]

This article deals with implementing a rule-based control method and startup sequence of a hybrid electric vehicle powered by a modular fuel cell system as its primary energy source and a lithium-ion battery system as its secondary energy source. The modular fuel cell system is composed of two separate fuel cell systems, electrically coupled to a one-power converter, using a programmable device. Depending on the vehicle’s operating mode, either both systems are used or just one of them. The vehicle’s fuel efficiency is improved by operating at constant power in the peak efficiency range of each fuel cell system. The experimental results show that the proposed system can significantly improve the fuel economy of a fuel cell vehicle and extend the driving range, while avoiding start/stop cycles. Additionally, this solution can increase the fuel cells’ lifecycle.

The fast frequency response (FFR) function in renewable energy source (RES)-based power stations has proved to be able to improve the frequency stability of power systems with high RES penetration significantly. However, most current FFR functions in photovoltaic (PV) power stations typically show power response deviations and unnecessary power loss issues that are caused by inadequate station power distribution strategies. This is particularly important in cases where the power must be increased when the system frequency shows a downward disturbance. This paper proposes a new distribution strategy for FFR in PV power stations and studies related distribution strategies, system structures, calculation algorithms, function execution effect, and active power regulation technology. The proposed approach uses a proportional distribution strategy based on an evaluation of the real-time potential maximum power capability values of the subarrays or generation regions, which are evaluated usin... [more]