Thermal bridges are a very relevant issue for lightweight steel-framed (LSF) construction systems given the high thermal conductivity of steel, which can negatively compromise their thermal behaviour, reduce their durability, and decrease the building energy efficiency. Several thermal bridge mitigation strategies exist, including the attachment of thermal break strips (TBS) to the steel studs’ flanges as one of the most widely employed techniques. In this research, the relevance of TBS to the thermal performance improvement of load-bearing LSF partition walls was assessed by performing a parametric study, making use of a validated 2D numerical model. A sensitivity analysis was performed for five different key parameters, and their importance was evaluated. The assessed parameters included the number of TBS and their thickness, width, and thermal conductivity, as well as the vertical steel stud spacing. We found that these parameters were all relevant. Moreover, regardless of the TBS t... [more]

The main objective of this study is to establish analytical feasibility for the deployment of solar panels in Qatar houses and other organisations; to calculate, by the use of analytical means, solar panel deployment scenarios with different panel sizes, efficiency, and sun per day, in order to estimate generated energy and compare that with actual consumption over a period of twelve months. In addition, the study aims to provide a comparative indicator on the ratio of generated energy to consumed energy and consumed electrical energy (GtoC), to establish the possibility of using the GtoC ratio as a new renewable energy rating index, for use in renewable energy investment and sales forecasting, in maintaining comparisons between different installation scenarios, and in upgrade planning and decision making. This study’s analytical solutions might be correlated with data from in situ solar panel installation scenarios in order to fully establish the performance under operational scenario... [more]

As an important part of carbon dioxide capture, utilization and storage (CCUS), the progress of injecting CO2 into oil reservoirs could increase the recovery rate and achieve large-scale carbon storage. It has become one of the most important carbon storage methods around the world. This paper selected the tight sandstone of the fourth member of the Quantou Formation in the southern Songliao Basin to carry out a CO2 storage physical simulation experiment. Representative samples were collected at 24 h, 72 h, 192 h and 432 h to study the CO2 water-rock interaction and to analyze the mineral composition, pore structure and the evolutionary characteristics of physical reservoir properties over time. Physical property analysis, Ion analysis, X-ray diffraction mineral analysis, QEMSCAN mineral analysis, scanning electron microscopy and high-resolution CT scanning techniques were adopted. The main points of understanding were: (i) It shows a differential evolution of different minerals follow... [more]

The storage of hydrogen is important for the development of hydrogen energy, especially for the storage of liquid hydrogen, which has been receiving more and more attention recently. In order to study the thermal insulation performance of variable-density multilayer insulation (VDMLI) structures under different working conditions at liquid hydrogen temperatures without incorporating a composite structure, we established a heat transfer model based on a layer-by-layer calculation method. Then, we carried out numerical calculations to analyze the influence of the total number of layers, the thermal boundary temperature, and vacuums on the performance of MLI at liquid hydrogen temperatures. To investigate the optimization of variable-density configurations on the thermal insulation performance of VDMLI and to obtain accurate variable-density configurations, we proposed a variable-density configuration method based on the control variable method and the insertion by region method. The resu... [more]

Low-carbon building regulations are acknowledged as critical instruments to facilitate the building industry’s decarbonization transition. However, recent studies have shown that non-compliance with low-carbon requirements is under-researched, leading to a significant divergence between policy intentions and actual performance. In light of this, the paper aims to provide a synthesis of existing research on non-compliance with low-carbon building regulations. It does this using a systematic literature review combined with bibliometric and text mining techniques. Through reviewing 26 scholarly works from the last decade, the paper demonstrates a peak production year around 2015, the year of the Paris Agreement, with the USA and Australia as key countries of concern. Subsequently, the study reveals three focused research areas: the development of building policy during the low-carbon transition; the role of building energy performance requirements in achieving low-carbon buildings; and bu... [more]

A hydrodynamic wind−wave combined power generation system is a new type of energy device that uses wind and ocean current energy to generate electricity. In this paper, the hydrodynamics of a wind−wave combined power generation system was simulated in Fluent. The fluid−structure coupling simulation of the vortex vibration of the cylindrical oscillator was realized using UDF and dynamic mesh technology. The Vortex-Induced Vibration (VIV) characteristics of the cylindrical oscillator were analyzed, and the reliability of the numerical simulation method was verified by comparing the amplitude and trajectory of the eddy-excited vibration with the classic experiments of Jauvtis and Williamson. The VIV characteristics of cylindrical oscillators with different mass ratios were studied in terms of vibration response, motion trajectory, and the streamwise equilibrium position. The effect of the mass ratio on the hydrodynamics of a wind−wave combined power generation system was simulated using s... [more]

Promoting the development of new energy vehicles is one of the important measures to ensure energy security and deal with global warming. Technological innovation is an inexhaustible driving force for the development of the new energy vehicle industry. This study considered listed enterprises in China’s new energy vehicle industry as research samples and used the fixed effect model to study the impact of government subsidies on the quantity and quality of technological innovation in the new energy vehicle industry. The empirical results show that government subsidies have a significant positive impact on the quantity of technological innovation in the new energy vehicle industry; however, government subsidies have no significant impact on the quality of technological innovation. Government subsidies increase the quantity of technological innovation in the new energy vehicle industry by increasing R&D investment, mitigating financing constraints, and improving the external attention of... [more]

The growth in the number of cars and the increasing demand for fuels require scientific work to develop alternative fuels. The energy crisis, which is becoming more and more evident, is not unimportant. The manuscript presents an analysis of the possibility of using agricultural biofuels to power a diesel engine. The analysis was carried out in relation to the operation of the engine on conventional fuels. The D-241 engine under investigation is mainly used for agricultural tractors. During the tests carried out, the load characteristics of the diesel engine under investigation were determined as a function of fuel type and speed. The concentrations of CO, HC and NOx were analysed. Laboratory tests of the engine were carried out with a wide range of external loads to evaluate measurement errors for the measurement method. Experiments with the engine under investigation have shown that the hourly and specific biofuel consumption of diesel engines increases by an average of 11−16%. CO an... [more]

Renewable energy consumption is one of the most important factors in meeting the goal of “30 and 60” in China. However, the maintenance of the transmission section affects the amount of generation transfer, further affecting the consumption of renewable energy. Hence, in this study, a time-series renewable energy production simulation (REPS) is proposed in order to accurately predict the power generation in a simulated situation. According to the results of the REPS, the sensitivity of the different sections’ maintenance can be calculated and determined. The appropriate maintenance strategies can be selected for different situations by comparing the consumption rate; as an example, we conducted a case study. The results show that the quota in the transmission section has higher sensitivity; a larger quota indicates a greater sensitivity to the consumption rate. The results also show that a larger quota is more suitable for maintenance in February or November, since the consumption rate... [more]

It is necessary to study different aspects of renewable energy generation, including wind energy. Wind power is one of the most important green and renewable energy resources. The estimation of wind energy generation is a critical task that has received wide attention in recent years. Different machine learning models have been developed for this task. In this paper, we present an efficient forecasting model using naturally inspired optimization algorithms. We present an optimized dendritic neural regression (DNR) model for wind energy prediction. A new variant of the seagull optimization algorithm (SOA) is developed using the search operators of the Aquila optimizer (AO). The main idea is to apply the operators of the AO as a local search in the traditional SOA, which boosts the SOA’s search capability. The new method, called SOAAO, is employed to train and optimize the DNR parameters. We used four wind speed datasets to assess the performance of the presented time-series prediction m... [more]

Production and consumption of confectionery products have increased worldwide, thus, effective management of wastewater produced is now an important issue. The confectionery high-load sewage was explored for biogas production in an innovative-design anaerobic reactor with labyrinth flow. The experimental studies were focused on determining the best technological parameters of anaerobic digestion for the effective removal of pollutants and obtaining high CH4 production efficiency. It was found that organic loading rate (OLR) of 5.0−6.0 g COD/L·d contributed to the highest CH4 generation of 94.7 ± 6.1 to 97.1 ± 5.1 L CH4/d, which corresponded to a high COD removal of 75.4 ± 1.5 to 75.0 ± 0.6%. Under such conditions the FOS/TAC ratio was below 0.4, indicating reactor stability, and pH was on the level of 7.15 ± 0.04 at OLR 5.0 g COD/L·d and 7.04 ± 0.07 at OLR 6.0 g COD/L·d.

The types of fractured-vuggy reservoirs are diverse, with dissolution holes and fractures of different scales as the main reservoir spaces. Clarifying the connectivity between wells is crucial for improving the recovery rate of fractured-vuggy reservoirs and avoiding problems of poor water- flooding balance and serious water channeling. A traditional dynamic connected model hardly describes the geological characteristics of multiple media, such as karst caves and fractures, which cause multiple solutions from the calculation. The static analysis is the basis for connectivity evaluation. In this study, we designed an intelligent search strategy based on an improved A* algorithm to automatically find a large-scale fractured-vuggy connected path by seismic multi-attribute analysis. The algorithm automatically evaluates the interwell-connected mode and clarifies the relationship between the static connected channel and the fractured-vuggy space configuration. Restricted by various factors,... [more]

The packing characteristics of a pebble bed are essential to understand the heat- and mass-transfer processes occurring within a granular system. Therefore, the packing characteristics of rectangular prismatic pebble beds randomly packed with mono-sized pebbles are analyzed. In terms of the average and local packing fraction distribution, coordination number, and radial distribution function, the effects of the rectangular tube aspect ratio and cross-sectional area on the packing properties of pebble beds are explored in depth. The findings indicate that the packing structures of the rectangular pebble bed exhibit noticeable fixed-wall effects. The average packing fraction and coordination number gradually decline as the rectangular tube aspect ratio rises. Close to the fixed wall, a noticeable wall effect can be seen in the distribution of axial and local packing fractions and the pebble center distribution. The wall effect has an increasing effect on the axial and local packing fract... [more]

The global industrial chain and energy supply chain are being reconfigured at an accelerated pace, and the uncertainty of China’s energy supply security is growing significantly. Empowering energy supply chains through the digital economy (diec) has a positive effect on accelerating the transformation of China’s energy supply structure. This paper discusses the effect and mechanisms of the digital economy on energy supply chain efficiency (esce). Specifically, based on the panel data of 112 energy enterprises in China from 2011 to 2019, energy supply chain efficiency and digital economy at the enterprise level were evaluated through three-stage DEA and content analysis, respectively. A two-way fixed effects model and mediation effect mode were adopted to investigate the nexus of diec and esce. The results show that the digital economy improves energy supply chain efficiency, and the conclusion holds water even after a series of robustness tests and endogenous treatment. Meanwhile, its... [more]

In the present work, numerical simulation and optimization was carried out to analyze the mechanism of the variable guide vanes (VGVs) of a transonic compressor. A seven-stage transonic compressor including three-stage VGVs was studied. The VGVs were adjusted individually and jointly under different IGV opening degrees. Changes in performance and shock wave were analyzed, and the coupling effect of the VGV joint adjustment was summarized. Aiming at the maximum efficiency, the joint turning angles were optimized. A novel phenomenon was found wherein the VGV adjustment can affect not only its own performance and that of adjacent downstream blades, but also that of upstream blades. Incidence and performance of upstream blades are improved, but those of the VGV and its adjacent downstream blades are deteriorated. VGV adjustment weakens the shock wave and shock-induced boundary layer separation. The optimal solution for VGV joint adjustment is the combination of the optimal solutions for si... [more]

The electrification of the transportation sector contributes to a cleaner environment in non-interconnected island (NII) systems or standalone islands. Moreover, e-mobility can significantly contribute to achieving very high renewable energy source (RES) penetration levels in islands, allowing a reduction both in the emissions due to the conventional generation and the system’s cost. Ιncreased RES penetration, however, can pose technical challenges for an island’s system. In order to overcome these challenges, new technologies like grid-forming converters are important. Moreover, the provision of new ancillary services in relation to battery storage systems might be considered, while novel control and protection schemes are needed to ensure secure operation. E-mobility can also contribute to solving technical problems that arise from very high RES penetration by providing frequency containment reserves or reactive power compensation. Since EV charging demand introduces modifications in... [more]

The Sixth Assessment Report of Inter-Governmental Panel on Climate Change (IPCC) has highlighted the urgency of accelerated climate actions harnessing synergies and minimizing trade-offs with various SDG. This calls for a clear understanding of linkages between climate goals and other SDGs at national level for formulating synergistic policies and strategies and developing different sectoral programs and coherent cross-sectoral policies. This is even more important for least developed countries such as Nepal where these linkages are less understood and development challenges are multifaceted. In this context, this paper aims to evaluate potential synergies and trade-offs among selected SDGs and their associated targets in Nepal in a linear pairwise comparison. Synergies and trade-offs related to climate action (SDG 13), access to energy (SDG 7), sustainable consumption and production (SDG 12), and life on land (SDG 15) have been evaluated using historical data for the period from 1990... [more]

Hydrogen is a promising commodity, a renewable secondary energy source, and feedstock alike, to meet greenhouse gas emissions targets and promote economic decarbonization. A common goal pursued by many countries, the hydrogen economy receives a blending of public and private capital. After European Green Deal, state members created national policies focused on green hydrogen. This paper presents a study of energy transition considering green hydrogen production to identify Portugal’s current state and prospects. The analysis uses energy generation data, hydrogen production aspects, CO2 emissions indicators and based costs. A comprehensive simulation estimates the total production of green hydrogen related to the ratio of renewable generation in two different scenarios. Then a comparison between EGP goals and Portugal’s transport and energy generation prospects is made. Portugal has an essential renewable energy matrix that supports green hydrogen production and allows for meeting Europ... [more]

Liquid fuel has been the main source of energy in internal combustion engines (ICE) for decades. However, lithium-ion batteries (LIB) have replaced ICE for environmentally friendly vehicles and reducing fossil fuel dependence. This paper focuses on the comparative analysis of battery thermal management system (BTMS) to maintain a working temperature in the range 15−35 °C and prevent thermal runaway and high temperature gradient, consequently increasing LIB lifecycle and performance. The proposed approach is to use biodiesel as the engine feed and coolant. A 3S2P LIB module is simulated using Ansys-Fluent CFD software tool. Four selective dielectric biodiesels are used as coolants, namely palm, karanja, jatropha, and mahua oils. In comparison to the conventional coolants in BTMS, mainly air and 3M Novec, biodiesel fuels have been proven as coolants to maintain LIB temperature within the optimum working range. For instance, the use of palm biodiesel can lightweight the BTMS by 43%, compa... [more]

A gravity-type heat pipe boiling characteristics test rig was constructed to solve the heat dissipation problem of fuel cells during operation. The boiling heat transfer characteristics of water in a parallel plate under negative pressure at different inclination angles and heat flow density input are investigated. The results show that: First, the gravity-type heat pipe can dissipate some heat and it is possible to use it for fuel cell heat dissipation. Second, with a certain range of heat flow density, the temperature of all parts of the plate is about 80 °C, with a small temperature difference, which is conducive to the safe operation of the fuel cell. Third, the heat flow density is in the range of 2222~3111 W·m−2, the temperature difference is large, and the outlet temperature is greater than 80 °C, which exceeds the operating temperature of the fuel cell, and the power-type heat pipe should be used for heat dissipation. Fourth, the average temperature of the plate placed at an in... [more]

The tanning industry generates significant amounts of solid waste and post-production wastewater, which should be managed in accordance with the principles of the circular economy. Waste is generated at various technological stages of production. This comprises mainly solid waste and leachate. A comprehensive solution to the problem of disposal of this waste is very important from economic and environmental points of view. This work presents research for a technological production line designed for the comprehensive processing of post-production residues. In the present paper, the authors present an analysis related to the possibility of processing leather flesh side (mizdra) as a substrate for methane fermentation. The study showed an increased biogas production from solid waste after enzymatic hydrolysis up to 248 Nm3/Mg. Preliminary research on the system designed for pre-treatment of sewage from the technological line is also presented. The study showed a COD reduction of more than... [more]

Due to the increasing demand for electricity around the world, different technologies have been developed to ensure the sustainability of each and every process involved in its production, transmission, and consumption. In addition to ensuring energy sustainability, these technologies seek to improve some of the characteristics of power systems and, in doing so, make them efficient from a financial, technical, and environmental perspective. In particular, solar photovoltaic (PV) technology is one of the power generation technologies that has had the most influence and development in recent years due to its easy implementation and low maintenance costs. Additionally, since PV systems can be located close to the load, power losses during distribution and transmission can be significantly reduced. However, in order to maximize the financial, technical, and environmental variables involved in the operation of an electrical system, a PV power generation project must guarantee the proper loc... [more]

The present study aimed to develop the electrical performance of outdoor insulators using a nano-TiO2 coating for railway electrification systems. The prototype design of porcelain insulators with normal coatings and using a nano-TiO2 coating is based on IEC 60815-1. The first test was performed to measure the low-frequency flashover AC voltage under both dry and wet conditions. In addition, the other test was conducted to measure the lightning impulse critical-flashover voltage at positive and negative polarity under dry-normal and wet-contaminated conditions. X-ray diffraction (X-RD) and Scanning electron microscopy (SEM) were used to examine the micro surface and show that the nano-TiO2 coating was adhered to the surface of the outdoor porcelain insulator and exists in an amorphous state. Additionally, it was observed and discovered that scattered nano-TiO2 strengthens the glassy matrix and creates a sturdy barrier that causes flashover voltage to be reduced under conditions of high... [more]

The disadvantages of fossil fuels and their impact on the environment have made the transition to renewable energy sources essential to cover our energy needs. However, different energy resources have a different impact on energy poverty conditions in the world, an issue that is important to examine and properly address. This study examines the impact that fossil fuels final energy consumption in households per capita and renewables and biofuels final energy consumption in households per capita have on energy poverty conditions in Europe, using panel data from 28 European countries for the time period 2004−2019 and static and dynamic regression models, while also performing various econometric tests. The findings indicate that GDP per capita and fossil fuels are linked to an inverse relationship to energy poverty conditions. Renewables and biofuels are also linked to an inverse relationship to the inability to keep homes adequately warm and the presence of leaks, damp, or rot in the dw... [more]

Rooftop solar photovoltaic (PV) systems could significantly contribute to renewable energy production and reduce domestic energy costs. In Italy, as in other countries, the current incentives generate a modest annual increase after the generous fiscal incentives that kick-started the PV market in the 2008−2013 period. Several factors are, however, at play that can speed up the installation process, such as the improvements in PV technology at declining prices, the increased availability of battery-storage (BS) systems, the growing use of electric appliances, the uptake of electric cars, and the increased environmental awareness. We integrate two research methodologies, discrete choice modeling and agent-based modeling, to understand how these factors will influence households’ decisions regarding PV and BS installations and how agents interact in their socioeconomic environment. We predict that in Italy, given the preference structure of homeowners, the continuing decline in costs, and... [more]