Search Results (6,506)

The residential sector accounts for over a third of the world’s energy use. Even though this ratio is lower in Mexico, there is a pressing housing deficit, especially regarding low-cost homes. This research aimed to create a reference building (RB) to understand the current energy consumption of multi-family buildings across different climatic zones. The aim was to assess their energy performance and promote reduced energy requirements as a guideline for designing and constructing affordable, low-energy, or zero-energy buildings. The present work conducts a diagnosis of the current energy consumption of multi-family buildings in eight cities in Mexico. First, a reference building was developed to represent typical Mexican building geometry and construction practices, and then the building’s fixed and variable energy requirements were simulated. Finally, a comparison was made between the energy requirement and the data reported by the national energy survey. Therefore, it was possible to generate a reference building from national data sources complying with national regulations, where materials, occupant behavior, and equipment were chosen to help represent the building’s thermal behavior. Domestic water heating was identified as a driver of variable energy requirements in all cities. In contrast, the simulated heating and cooling requirements were directly linked to the city’s climate. Electricity bills tended to mostly correspond with the results that excluded the use of heating systems. Lastly, while comparing LPG (Liquified Petroleum Gas) consumption was challenging due to the unavailability of national data, LPG requirements were closely estimated for temperate cities. The definition of a reference building is an important step towards developing nZEB in Mexico, as these buildings are valuable tools that can contribute to the energy evaluation of specific types of buildings. This characteristic makes them convenient for revising a building code or setting new national energy policy goals. Full article

In Europe and elsewhere in the world, current ambitious decarbonization targets push towards a gradual decommissioning of all fossil-fuel-based dispatchable electrical generation and, at the same time, foster a gradual increase in the penetration of Renewable Energy Sources (RES). Moreover, considerations tied to decarbonization as well as to the security of supply, following recent geo-political events, call for a gradual replacement of gas appliances with electricity-based ones. As RES generation is characterized by a variable generation pattern and as the electric carrier is characterized by scarce intrinsic flexibility, and since storage capabilities through electrochemical batteries, as well as demand-side flexibility contributions, remain rather limited, it is quite natural to think of other energy carriers as possible service providers for the electricity system. Gas and heat networks and, in the future, hydrogen networks could provide storage services for the electricity system. This could allow increasing the amount of RES penetration to be managed safely by the electric system without incurring blackouts and avoiding non-economically motivated grid reinforcements to prevent the curtailment of RES generation peaks. What is explained above calls for a new approach, both in electricity network dispatch simulations and in grid-planning studies, which extends the simulation domain to other carriers (i.e., gas, heat, hydrogen) so that a global optimal solution is found. This simulation branch, called multi-energy or multi-carrier, has been gaining momentum in recent years. The present paper aims at describing the most important approaches to static ME modeling by comparing the pros and cons of all of them with a holistic approach. The style of this paper is that of a tutorial aimed at providing some guidance and a few bibliographic references to those who are interested in approaching this theme in the next years. Full article

This review explores the structural and electrochemical characteristics of carbon materials derived from polybenzoxazines, emphasizing their potential in supercapacitors. A detailed analysis of thermal degradation by-products during carbonization reveals distinct competing mechanisms, underscoring the exceptional thermal stability of benzoxazines. These materials exhibit significant pseudocapacitive behavior and excellent charge retention, making them strong candidates for energy storage applications. The versatility of polybenzoxazine-based carbons enables the formation of diverse morphologies—nanospheres, foams, films, nanofibers, and aerogels—each tailored for specific functionalities. Advanced synthesis techniques allow for precise control over porosity at the nanoscale, optimizing performance for supercapacitors and beyond. Their exceptional thermal stability, electrical conductivity, and tunable porosity extend their utility to gas adsorption, catalysis, and electromagnetic shielding. Additionally, their intumescent properties (unique ability to expand when exposed to high heat) make them promising candidates for flame-retardant coatings. The combination of customizable architecture, superior electrochemical performance, and high thermal resistance highlights their transformative potential in sustainable energy solutions and advanced protective applications. Full article

Heat recovery systems are increasingly recognized as key energy conservation measures in residential buildings. But their effectiveness is highly sensitive to operational conditions. This study used a calibrated OpenStudio simulation, which is validated against monthly utility data, to investigate the feasibility of implementing a heat recovery ventilator in an existing single-detached house in Vancouver under two scenarios: existing passive ventilation without a heat recovery ventilator versus the proposed balanced mechanical ventilation with a heat recovery ventilator. The findings indicate that employing an HRV in an existing house lacking balanced ventilation would lead to higher annual space heating energy consumption (75.49 GJ electricity and 56.70 GJ natural gas with HRV compared to 73.64 GJ and 52.70 GJ, respectively, without an HRV). Therefore, for existing houses without balanced ventilation, improving the existing building envelope’s airtightness through retrofits should always be carried out before installing a heat recovery ventilator. Additionally, the heat recovery ventilator should be appropriately sized to compensate for any shortfall in natural infiltration to ensure the sufficient indoor air quality while minimizing the outdoor air-induced space heating energy usage. Furthermore, the recommended break-even point of the infiltration rate for the house studied in this work to avoid increased space heating energy use due to the retrofit with a heat recovery ventilator is 0.281 air change per hour. Full article

Biogas (primarily biomethane), as a carbon-neutral renewable energy source, holds great potential to replace fossil fuels for sustainable hydrogen production. Conventional biogas reforming systems adopt strategies similar to industrial natural gas reforming, posing challenges such as high temperatures, high energy consumption, and high system complexity. In this study, we propose a novel multi-product sequential separation-enhanced reforming method for biogas-derived hydrogen production, which achieves high H₂ yield and CO₂ capture under mid-temperature conditions. The effects of reaction temperature, steam-to-methane ratio, and CO₂/CH₄ molar ratio on key performance metrics including biomethane conversion and hydrogen production are investigated. At a moderate reforming temperature of 425 °C and pressure of 0.1 MPa, the conversion rate of CH₄ in biogas reaches 97.1%, the high-purity hydrogen production attains 2.15 mol-H₂/mol-feed, and the hydrogen yield is 90.1%. Additionally, the first-law energy conversion efficiency from biogas to hydrogen reaches 65.6%, which is 11 percentage points higher than that of conventional biogas reforming methods. The yield of captured CO₂ reaches 1.88 kg-CO₂/m³-feed, effectively achieving near-complete recovery of green CO₂ from biogas. The mild reaction conditions allow for a flexible integration with industrial waste heat or a wide selection of other renewable energy sources (e.g., solar heat), facilitating distributed and carbon-negative hydrogen production. Full article

Zr₄₈Cu_47.5Al₄Co_0.5 bulk amorphous alloy composites were prepared by selective laser melting (SLM) technology under different processing conditions and their non-isothermal crystallization behaviors were systematically investigated. The results show that the crystallization phases are Cu₁₀Zr₇ and CuZr₂ for both gas-atomized powder and SLMed samples. The dependence of volume fraction of Cu₁₀Zr₇ and CuZr₂ on laser energy density can be fitted by an exponential function. The crystalline sizes of Cu₁₀Zr₇ and CuZr₂ linearly increase with increasing energy density. The thermal stability is larger for the gas-atomized powders than for the SLMed bulk samples. It is interestingly found that there is an exponential relationship between the crystallization enthalpy ΔH_x and the amorphous content. In addition, the glass transition is more difficult for the gas-atomized powders than for the SLMed bulk samples. The crystallization procedure is more difficult for the SLMed bulk samples than for the gas-atomized powders. The local activation energy E_α decreases with increasing α for the gas-atomized powder and the SLMed bulk samples. In addition, the E_α is larger for the SLMed bulk samples than for the gas-atomized powder at the corresponding crystallization fraction α. The dependence of the local Avrami exponent n(α) on the α is similar for both the gas-atomized powders and the SLMed bulk samples at studied heating rates. The crystallization mechanism is also discussed. Full article

FeSiBCuNb powders, produced via the gas–water atomization method, typically exhibit a broad particle size distribution and high sphericity. Nanocrystalline soft magnetic composites derived from these powders demonstrate exceptional service stability. In this study, a series of FeSiBCuNb/FeNi nanocrystalline magnetic powder cores (NMPCs) were fabricated under varying compaction pressures and heat treatment temperatures. The effects of these parameters on the soft magnetic properties were systematically analyzed. The findings reveal that optimizing compaction pressure and heat treatment temperature significantly enhances the density of the composite powders, leading to improved magnetic permeability and reduced core loss; when compaction pressure is 1800 MPa and heat treatment temperature is 550 °C, the NMPCs display outstanding magnetic properties with a low H_c of 6.32 Oe, high μ_e of 71.9, a low P_cv of 86.3 kW/m³ at 50 mT and 100 kHz, and 351.5 kW/m³ at 20 mT and 1000 kHz. Therefore, tailoring these processing conditions can enhance the soft magnetic performance of FeSiBCuNb nanocrystalline composites. Full article

This research investigates the application of activated tungsten inert gas (A-TIG) welding on boiler grade SA516 Grade 70 carbon steel using nano titanium dioxide (TiO₂) nano flux to enhance weld penetration depth, microstructure, and mechanical properties. A unique flux application technique was devised and experiments were carried out. Response Surface Methodology (RSM) was utilized to optimize weld parameters, namely arc length, welding current, and travel speed.The selection between A-TIG and TIG welding significantly influences penetration depth, as A-TIG benefits from arc constriction and elevated current density. The welding speed is crucial for controlling heat input, whereas current and arc length enhance penetration by influencing arc force and energy distribution. Optimizing all three parameters guarantees optimal penetration and weld quality. Microstructural research revealed enhanced mechanical properties in A-TIG weldments, distinguished by acicular ferrite in the fusion zone, which augmented toughness and tensile strength (520 MPa) compared to TIG weldments (470 MPa) and the base metal (480 MPa). Although A-TIG welds exhibited reduced impact toughness (68 J) relative to the base metal (128 J), A-TIG joints had superior ductility. The findings of this research clearly demonstrate the A-TIG welding process improved the depth of penetration and mechanical strength of the weld joints. Full article

This study applies machine learning (ML) techniques to classify fertile [for porphyry Cu and (or) Au systems] and barren adakites using geochemical data from New Brunswick, Canada. It emphasizes that not all intrusive units, including adakites, are inherently fertile and should not be directly used as the heat source evidence layer in mineral prospectivity mapping without prior analysis. Adakites play a crucial role in mineral exploration by helping distinguish between fertile and barren intrusive units, which significantly influence ore-forming processes. A dataset of 99 fertile and 66 barren adakites was analyzed using seven ML models: support vector machine (SVM), neural network, random forest (RF), decision tree, AdaBoost, gradient boosting, and logistic regression. These models were applied to classify 829 adakite samples from around the world into fertile and barren categories, with performance evaluated using area under the curve (AUC), classification accuracy, F1 score, precision, recall, and Matthews correlation coefficient (MCC). SVM achieved the highest performance (AUC = 0.91), followed by gradient boosting (0.90) and RF (0.89). For model validation, 160 globally recognized fertile adakites were selected from the dataset based on well-documented fertility characteristics. Among the tested models, SVM demonstrated the highest classification accuracy (93.75%), underscoring its effectiveness in distinguishing fertile from barren adakites for mineral prospectivity mapping. Statistical analysis and feature selection identified middle rare earth elements (REEs), including Gd and Dy, with Hf, as key indicators of fertility. A comprehensive analysis of 1596 scatter plots, generated from 57 geochemical variables, was conducted using linear discriminant analysis (LDA) to determine the most effective variable pairs for distinguishing fertile and barren adakites. The most informative scatter plots featured element vs. element combinations (e.g., Ga vs. Dy, Ga vs. Gd, and Pr vs. Gd), followed by element vs. major oxide (e.g., Fe₂O₃T vs. Gd and Al₂O₃ vs. Hf) and ratio vs. element (e.g., La/Sm vs. Gd, Rb/Sr vs. Hf) plots, whereas major oxide vs. major oxide, ratio vs. ratio, and major oxide vs. ratio plots had limited discriminatory power. Full article

PVC has become an indispensable material worldwide. However, its production method (suspension) presents significant sustainability challenges, such as negative environmental impacts and high operational costs due to energy consumption. For this reason, a combined analysis was conducted involving energy integration using Aspen Energy Analyzer™ V14 software and a technical process analysis. This methodology aims to reduce industrial utility consumption and assess the sustainability performance of this alternative. The integration through pinch analysis revealed that it is possible to reduce the energy consumption of the process by 29% in heating utilities and 6% in cooling utilities. The minimum utility requirements were 21 GJ/h for heating (down from 29 GJ/h) and 131 GJ/h for cooling (down from 139 GJ/h). This reduction resulted in approximately a 41% decrease in utility costs. Additionally, the reduction in burner energy consumption led to lower greenhouse gas emissions, with a decreased natural gas consumption of approximately 279 m³. However, only two streams could be integrated due to technical process limitations; therefore, it is recommended to explore integrations with complex operations such as reactors and phase-change processes. In addition to this, the WEP technical evaluation yielded promising results showing a decrease in the specific energy intensity by 3219.506 MJ/t (being 4681.8 MJ/t), which represents an economic saving in industrial services (energy purposes) of approximately USD 886.000 per year, satisfying the optimization of the process despite the limitations when integrating it energetically. Finally, a more in-depth analysis should be conducted to further integrate other streams of the process to reduce utilities consumption. Full article

Hydrogen prereduction of two manganese ores fines was investigated under varied operating conditions in a fluidized bed. The manganese ores used in this study are the Zambian ore and the South African Nchwaneng ore from the Kalahari region. The samples were milled and sized before they were characterized with regard to sphericity, Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) chemical analyses, X-ray diffraction (XRD) analyses and Scanning Electrons Microscope (SEM) analyses. Prereduction experiments were conducted in a laboratory scale fluidized bed with the parameters of interest being minimum fluidization velocity, terminal velocity, elutriation, average bed voidage, residence time, temperature, intrinsic ore properties and cohesive adhesion. Experiments for the determination of fluidization velocity and terminal velocity were conducted at both ambient temperature and elevated temperature ($500 °$C, $550 °$C, $600 °$C, $700 °$C, $800 °$C and $900 °$C), and for varied sample masses (100 g, 300 g and 700 g) and varied particle-size ranges (200–$300 \mathrm{\mu }$m, 300–$425 \mathrm{\mu }$m, 425–$500 \mathrm{\mu }$m and 500–$600 \mathrm{\mu }$m). The experimentally observed minimum fluidization velocities for particles size groupings of [+106–$200 \mathrm{\mu }$m], [+200–$300 \mathrm{\mu }$m], [+300–$425 \mathrm{\mu }$m], [+425–$500 \mathrm{\mu }$m] and [+500–$600 \mathrm{\mu }$m] as well as the mix (20 wt% of each) was comparable with the theoretical minimum fluidization velocity. The fluidized bed was heated to a desired temperature at a rate of $10 °$C/min under argon whilst logging the pressure drop across the bed with increasing temperature. The convectional cooling during the introduction of cold hydrogen as well as the net energy of endothermic and exothermic chemical reactions were observed to result in a temperature drop in the order of 100 to $250 °$C. Thermal mineral transformation under argon was observed to yield iron manganese oxide in the order of 15 to 30 wt/wt%. Prereduction was conducted using hydrogen gas at a desired temperature and terminal velocity. Reduction extent was observed to increase with the increasing temperature and residence time. Increasing reduction temperature beyond $700 °$C was not observed to improve reduction, whereas longer residence time (of up to 40 min) was observed to favor the formation of iron manganese oxide, iron manganese and manganosite. For hydrogen prereduction experiment conducted at $900 °$C, the reactor was observed to be brittle after the experiment. Cohesive adhesion was observed to be more pronounced at $900 °$C. Full article

In Europe, renewable energy sources such as photovoltaic panels and wind power plants are developing dynamically. The growth of renewable energy is driven by rising energy prices, greenhouse gas emission restrictions, the European Union’s Green Deal policy, and decarbonization efforts. Photovoltaic farms generate energy intermittently, depending on weather conditions. Given the increasing number of new installations, ensuring the power balance and transmission capacity of the electrical grid has become a major challenge. To address this issue, the authors propose a technical solution that allows the energy generated by photovoltaic systems to be stored in the form of heat. Thermal energy from solar power and wind energy offers significant potential for energy storage. It can be accumulated during summer in specially designed sand-based heat storage systems and then used for heating purposes in winter. This approach not only reduces heating costs but also decreases greenhouse gas emissions and helps balance the power grid during sunny periods. Post-industrial areas, often located near city centers, are suitable locations for large-scale heat storage facilities supplying, among others, public utility buildings. Therefore, this article presents a concept for utilizing high-temperature sand-based heat storage systems built in decommissioned underground mining excavations. Full article

To address the challenge of heat transfer enhancement in the condensation of steam with non-condensable gases on a vertical wall under natural convection conditions, an improved boundary layer model with coupled multi-physics field was proposed in this paper, and traditional theoretical limitations were broken through by innovations. The particle swarm optimization algorithm was first introduced into the solution of the condensation boundary layer, and the convergence difficulty in the laminar–turbulent transition region under infinite boundary conditions was overcome. A coupled momentum–energy–mass equation system that simultaneously considered temperature–concentration dual-driven gravity terms and liquid film drag–suction dual effects was established, and higher computational efficiency and accuracy were achieved. A new mechanism where the concentration boundary layer dominated heat transfer resistance under the coupled action of the Prandtl number (Pr) and Schmidt number (Sc) was revealed. Experimental validation demonstrated that a prediction error of less than 5% was exhibited by the model under typical operating conditions of passive containment cooling systems (pressures of 1.5–4.5 atm and subcooling temperatures of 14–36 °C), and a theoretical tool for high-precision condensation heat transfer design was provided. Full article

This study aims to assess the environmental impact of using wood-based biomass as a high-efficiency fuel alternative to fossil fuels for heat production. To achieve this, the life cycle of biomass transformation, utilization, and disposal was analyzed using the life cycle assessment (LCA) methodology with SimaPro 9.5.0.2 PhD software. The system boundaries included extraction, processing, transportation, combustion, and waste management, following a cradle-to-gate approach. A comparative analysis was conducted between natural gas, the most widely used conventional heating fuel, and two biomass-based fuels: wood pellets and wood chips. The results indicate that biomass utilization reduces greenhouse gas emissions (−19%) and fossil resource depletion (−16%) while providing environmental benefits across all assessed impact categories analyzed, except for land use (+96%). Biomass is also to be preferred for forest waste management, ease of supply, and energy independence. However, critical life cycle phases, such as raw material processing and transportation, were found to contribute significantly to human health and ecosystem well-being. To mitigate these effects, optimizing combustion efficiency, improving supply chain logistics, and promoting sustainable forestry practices are recommended. These findings highlight the potential of biomass as a viable renewable energy source and provide insights into strategies for minimizing its environmental footprint. Full article

Sustainability has become an important focus in the construction industry due to growing environmental concerns, resource depletion, and the urgency to reduce greenhouse gas emissions. The construction sector contributes significantly to the world’s carbon emissions and energy consumption, making it a prime candidate for sustainable transformation. In response to these challenges, there has been a shift towards utilizing earth-based products, especially earth blocks, as sustainable alternatives. Compressed stabilized earth blocks (CSEBs) are garnering increased attention because of their ability to lower environmental impact. These blocks are made from locally sourced materials, reducing the transportation-related emissions and energy use. Their production processes typically require far less energy than traditional building blocks, which results in reduced carbon footprints. Earth blocks also contribute to sustainability through their thermal performance, which can enhance energy efficiency in buildings by naturally regulating indoor temperatures. As a result, less artificial heating and cooling is required, leading to further energy savings. Furthermore, CSEBs and other earth blocks can incorporate waste materials promoting a circular economy and resource efficiency. This paper explores the multifaceted role of earth blocks in sustainable construction by conducting a comprehensive systematic and bibliometric analysis. By evaluating research trends, the evolution of the field, and the broader impact of these materials, this study aims to provide a deeper understanding of the contributions of earth blocks to sustainability. Key areas of focus include identifying prominent research themes, emerging technologies, and future opportunities for incorporating earth blocks into mainstream construction practices. This approach aligns with the vision of advancing sustainable architecture and green buildings to minimize environmental pollution and resource consumption while supporting the transition to a circular economy in the built environment. Full article