Search Results (834)

Hydrogen oxy-combustion with high CO₂ dilution is a key component of supercritical CO₂ (sCO₂) power cycles, such as the Allam cycle, enabling high-efficiency, near-zero-emission power generation with integrated carbon capture. However, combustion behavior under high-CO₂ conditions remains insufficiently characterized, particularly with respect to mixing and flame stability. In this study, hydrogen combustion in an O₂–CO₂ environment was investigated experimentally and numerically using a custom-designed multi-hole burner. The experiments were conducted in a 1-bar combustion chamber, while the inlet pressures of the reactants were varied between 10 and 50 bar to isolate the effect of injection conditions. Numerical simulations were performed to analyze flow, mixing, and flame structure. The results show that increasing inlet pressure leads to a more compact and localized flame, despite reduced velocity levels in the combustor due to increased reactant density. Higher inlet pressures result in increased peak temperatures but lower mean combustor temperatures, indicating more intense but spatially confined heat release. The flow field remains structurally similar across cases, while reduced radial spreading and longer residence times influence combustion behavior. Stable flame operation was achieved over a wide range of conditions, demonstrating the feasibility of hydrogen oxy-combustion under high CO₂ dilution. The combined experimental and numerical analysis provides insight into the interplay between injection conditions, mixing, and reaction rates in highly CO₂-diluted hydrogen combustion. The obtained results support the development of compact and stable direct-fired combustors for next-generation supercritical CO₂ power cycles and hydrogen-based low-emission energy systems. Full article

Textile membrane systems are increasingly used in sports halls because of their low structural weight, rapid assembly, and ability to span large areas. Their operational performance, however, is strongly affected by local climate conditions, envelope configuration and the limited thermal inertia of membrane materials. This study presents a comparative EnergyPlus-based assessment of textile membrane sports halls in six representative climate contexts: Helsinki, Berlin, Niš, Barcelona, Dawadmi and Bangkok. A conventional masonry hall was used as the reference case and compared with a single-layer PVC-coated polyester membrane system and double-layer membrane systems with air gaps of 0.4, 0.5 and 0.6 m, including mechanically ventilated air-cavity variants. The assessment combines four performance indicators: annual operational energy demand, carbon emissions, indicative global cost and thermal comfort expressed through Fanger’s Predicted Percentage of Dissatisfied (PPD) index. The results show that the dominant energy demand is climate-dependent, with heating prevailing in cold climates and cooling becoming decisive in hot-arid and hot-humid climates. Double-layer cases usually show lower operational energy demand and lower associated carbon dioxide emissions than the single-layer membrane case. This improvement, however, is not uniform; it depends on the climatic setting and on the width of the air gap. The comfort results lead to a similar but more limited conclusion. Although PPD is reduced in the double-layer configurations, the values remain above conventional comfort acceptance levels in all tested cases. The double-layer membrane should therefore be understood as a measure that reduces thermal dissatisfaction, not as a complete comfort solution. The economic assessment indicates that membrane systems have substantially lower initial capital costs than masonry construction, while their long-term performance depends on operational energy costs, membrane replacement assumptions and the selected analysis horizon. The study provides a climate-specific comparative framework for early-stage envelope selection in textile membrane sports halls, emphasizing that energy demand, carbon emissions, cost and thermal comfort should be considered together rather than as separate outputs. Full article

The synergistic utilization of post-mining spaces and geothermal energy through underground seasonal thermal energy storage (USTES) provides a promising pathway for sustainable heating and the low-carbon redevelopment of mining regions. To advance the thermal management and reveal the thermo-hydraulic evolution patterns within these repurposed environments, this study proposes an integrated approach that utilizes post-mining roadways as heat storage reservoirs, within the scope of a single idealized case study. A comprehensive USTES heating system model was established to systematically evaluate operational characteristics and environmental impacts under diverse conditions assuming homogeneous rock properties and idealized thermal boundaries. Results demonstrate that the surrounding ground temperature and the low thermal conductivity of the rock mass contribute to limiting heat dissipation and maintaining stable seasonal storage performance. For a roadway with a 20,000 m³ water storage capacity and an optimal 3900 m² solar collector area, the system successfully satisfies the thermal demand of 30,000 m² of building area. The configuration achieves 1239 MWh of cumulative heat storage over a 245-day cycle, maintaining a direct heating-to-heat-pump-upgraded heating ratio of 1.02. Furthermore, the implementation of variable-frequency thermal management strategies demonstrates remarkable economic and environmental superiority, yielding a 35.8% cost reduction compared to coal-fired heating, an overall energy saving rate of 77.5% relative to electric heating systems and a 13.5% decrease in CO₂ emissions relative to gas-fired systems. This research provides fundamental design parameters for the synergistic exploitation of mineral and geothermal resources, advancing the development of green heating and the sustainable utilization of post-mining spaces. Full article

Tri-reforming of methane (TRM) has emerged as a promising pathway for low-carbon syngas production by integrating steam reforming, dry reforming, and partial oxidation within a single process. This coupling enables simultaneous CH₄ utilization and CO₂ valorization while enabling internal heat generation and flexible adjustment of the H₂/CO ratio for downstream synthesis. However, TRM performance cannot be adequately evaluated using conversion or energy efficiency alone, because the process involves complex interactions among competing reaction pathways, transport phenomena, catalyst stability, and thermodynamic irreversibility. This review provides a multiscale critical assessment of TRM from both first-law energy and second-law exergy perspectives, linking reaction-network fundamentals to reactor-level behavior and system-level performance. The literature evidence shows that although high temperatures and near-autothermal operation can enhance CH₄ conversion and reduce external heat demand, these conditions may simultaneously intensify deep oxidation, hotspot formation, carbon-forming tendencies, and exergy destruction. While equilibrium analyses help define feasible operating windows, they are insufficient without kinetic modeling and reactor-scale studies that capture spatial non-uniformities and pathway competition. Across reported TRM systems, exergy destruction is consistently concentrated within the reformer, identifying the reacting core as the dominant thermodynamic bottleneck. Accordingly, the key challenge in TRM is not simply to maximize conversion but to preserve chemical work potential while maintaining syngas quality and operational stability. Viewed from this perspective, TRM is better understood as an irreversibility-aware multiscale design problem in which optimal performance depends on the integrated optimization of catalyst functionality, reactor architecture, heat management, and system-level operation. Full article

The decarbonisation of the building sector represents a key challenge for the European energy transition, particularly in the heating segment, which is still largely dependent on fossil fuels. In this context, data centres (DCs) offer a promising opportunity as local sources of recoverable waste heat. This study investigates the use of data centre waste heat for building heating through a comparative annual energy analysis applied to two building typologies in a Mediterranean climate (Italy): a residential building and a school. Three scenarios are considered: non-integrated scenario S0 (data centre with its own cooling system and buildings with gas-fired boilers), non-integrated scenario S1 (data centre with its own cooling system and buildings with air-to-water heat pumps), and integrated scenario S2 (data centre cooling system coupled with the buildings through waste heat recovery and heat pump technology). A theoretical 300 kW data centre was considered as the waste heat source. The integrated scenario significantly improves system performance. In the residential case, the seasonal COP increases from 2.15 to 4.50, reducing electricity consumption from 289.5 MWh to 128.9 MWh. In the school case, the COP increases from 2.51 to 8.00, with electricity consumption decreasing from 161.3 MWh to 49.1 MWh. These improvements lead to reductions in non-renewable primary energy demand of up to 63% and 79% for the residential and school buildings, respectively, compared to the baseline scenario. The results demonstrate that data centres can act as decentralised thermal sources, supporting the transition towards low-carbon and Nearly Zero-Energy Buildings. Full article

Cement clinker production is a thermal- and emissions-intensive process requiring high-temperature heat for drying, calcination, and sintering. This review provides a process-based assessment of refuse-derived fuel (RDF), solid recovered fuel (SRF), tire-derived fuel (TDF), and biomass as partial substitutes for coal and petcoke in modern dry-process cement kilns. The study synthesized the evidence from plant-scale trials, pilot and laboratory experiments, process modeling, computational fluid dynamics, emissions studies, life-cycle assessment (LCA), techno-economic analysis (TEA), and regional case studies to evaluate alternative fuels across fuel properties, kiln-zone suitability, process stability, clinker quality, emissions performance, and environmental outcomes. The review shows that stable co-processing generally requires fuels with net calorific values above 14 MJ kg⁻¹ and moisture contents below 15%, although TDF can provide 26–33 MJ kg⁻¹ and sustain high-energy kiln duty when sulfur, zinc, and steel residues are controlled. RDF, SRF, and biomass require pre-processing, homogenization, calibrated dosing, and continuous fuel-quality monitoring to limit incomplete burnout, deposit formation, volatile circulation, and clinker-quality variation. LCA studies show that 20% RDF thermal substitution can reduce global warming potential by about 3.3–4.2%, increasing to approximately 6.7% when avoided landfill methane credits are included. Modern abatement systems can maintain particulate matter at about 10–30 mg Nm⁻³ and PCDD/F below 0.1 ng TEQ Nm⁻³ under stable operation. The review concludes that alternative fuels are quality-dependent co-processing options whose mitigation role is complementary to clinker-factor reduction, energy-efficiency improvement, low-clinker binders, electrified heating, oxy-fuel calcination, and carbon capture. Full article

To address the issues of high energy consumption, high carbon emissions, and the waste of associated energy (AE) in coal mine production, which severely hinder global sustainable development goals, this paper proposes a novel low-carbon economic collaborative optimal scheduling model for a coal mine integrated energy system (CMIES) oriented towards sustainable energy transitions. First, a refined utilization model for AE encompassing coal mine gas, ventilation air methane (VAM), and mine groundwater (GW) is constructed, and a tiered carbon emission trading mechanism (TCET) is introduced to constrain carbon emissions and promote ecological sustainability. Second, a concentrated solar power (CSP) plant is integrated to break the rigid “power determined by heat” constraint of a traditional combined heat and power (CHP) unit, thereby enhancing the system’s scheduling flexibility and renewable energy integration. Meanwhile, abandoned mines are retrofitted into solvent storage tanks to construct an integrated flexible carbon capture system (IFCCS), achieving sustainable reuse of mining wastelands. Finally, to tackle the multi-source, heterogeneous uncertainties on both the source and load sides, a hybrid risk assessment method combining information gap decision theory (IGDT) and conditional value at risk (CVaR) is proposed. Case study results demonstrate that, compared to traditional energy supply modes, the proposed model reduces carbon emissions and total costs in the mining area by 66.04% and 15.97%, respectively. This significantly improves resource utilization efficiency and ecological benefits, providing a highly viable pathway for the sustainable development and clean transition of coal mine operations. Furthermore, the proposed hybrid assessment method can effectively assist decision-makers in achieving a refined trade-off between operating costs and system robustness under varying risk preferences. Full article

Conventional full-space heating systems waste massive fossil-derived energy on unoccupied indoor areas and cause uncomfortable “warm head, cold feet” issues against sustainable building targets. To fill this gap and advance low-carbon indoor heating solutions for sustainable office development, this study proposes an innovative localized heating terminal combining radiant panels and downward laminar air supply. An experimental platform was established, with twelve testing cases covering varied supply air velocity, supply air temperature and radiant panel temperature to explore its thermal comfort and energy-saving sustainability performance. Experimental results demonstrate that, under the optimal operating condition (0.55 m/s airflow, 23.5 °C supply air, 36 °C radiant panel), the vertical head–foot temperature difference reduces to merely 1.2 °C, far below the 3–5 °C threshold of conventional heating equipment; the draught rate approaches zero to eliminate cold draft discomfort. Critically, 65–75% of total supplied heat concentrates within human-occupied zones, drastically cutting redundant heat loss and advancing building heating sustainability. The terminal features dual working modes: convection contributes 78.7–94.4% of total heat for rapid warm-up while radiant heat maintains stable long-term comfortable surroundings. Such flexible dual-mode design supports sustainable part-load operation matching intermittent office occupancy, making this terminal a feasible low-carbon option for modern sustainable office buildings prioritizing energy efficiency and a healthy indoor environment. Full article

The successful realization of a circular economy in the cement industry, coupled with a substantial reduction in carbon emissions, relies on the development of sustainable alternative binder systems. This study investigated the physicomechanical performance and sulfate resistance of composites produced by alkali activation of natural perlite and blast furnace slag. The aim of the research was to improve mechanical properties under low- and medium-alkalinity conditions (5–10 M NaOH). The samples were cured at an ambient temperature of 20 °C and then treated with heat at 60 °C. These samples were then mechanically processed and subjected to five soak–dry cycles in 5% and 10% Na₂SO₄ solutions. The results showed that heat treatment resulted in the formation of a dense C-A-S-H gel, increasing compressive strength approximately eightfold, from 11.64 MPa to 92 MPa. However, perlite’s porous and brittle structure limits its flexural strength to 0.27 MPa; this value is insufficient for structural applications. Under severe sulfate attack (10% Na₂SO₄), samples cured at ambient temperature showed a 12% mass increase in the first cycle due to solution infiltration into capillary voids. As a consequence of extensive ettringite and gypsum formation, the specimens experienced severe deterioration, resulting in a complete loss of mechanical integrity and a residual compressive strength of 0 MPa. In contrast, heat-treated samples showed limited ion diffusion due to a denser matrix and an improved aggregate interface transition zone, resulting in a 2.6% mass increase and a residual compressive strength of 5.17 MPa. Consequently, the obtained findings indicate that thermally treated alkali-activated slag–perlite composites exhibit high resistance against sodium sulfate attack and may have potential for use in specific industrial environments with high sulfate concentrations. However, the performance of these materials under more complex aggressive conditions, such as mining environments involving magnesium sulfate exposure and acidic drainage waters, should be further validated through future studies. Full article

Power batteries used in electric-powered vessels, new-energy tractors or construction machinery typically require prolonged, continuous operation at high power levels, which can lead to significant heat buildup and pose serious threats to battery safety, cycle life, and operational stability. Traditional air-cooled and liquid-cooled systems struggle to meet the requirements for efficient heat dissipation under heavy loads. Phase change materials (PCMs) are ideal for passive battery thermal management due to their high latent heat but are severely limited by low thermal conductivity and liquid leakage. In this study, nitrogen-doped carbon nanotubes@SiO₂ (PNT@SiO₂) were synthesized and further fabricated into oriented porous aerogels by directional freeze-drying using cellulose-based materials as the skeleton. Polyethylene glycol-8000 (PEG-8000) was loaded via vacuum impregnation to obtain the PSAP composite PCM. The optimized composite exhibits a thermal conductivity of 0.93 W/m·K, 3.2 times that of pure PEG, with 96% PEG loading and a phase change enthalpy of 158 J/g. Battery thermal management tests demonstrate its excellent temperature control and heat suppression performance. This study provides a high-performance and feasible thermal management solution for power batteries used in relevant fields. Full article

Carbon nanotubes (CNTs) are commonly used to reinforce and functionalize cement matrices, thereby imparting new properties. To facilitate the introduction of CNTs into inorganic matrices such as cement, the use of a master batch is advantageous. In this approach, the CNTs are premixed with a carboxymethyl cellulose (CMC) to form this master batch, which enables homogeneous dispersion and simplifies the mixing of all components (cement, CNTs, CMC, and water). The system, a CNT–CMC–cement mixture, is modeled here by using a molecular dynamics simulation. Three models were constructed for comparative analysis: pristine tobermorite 11Å (T11) for hydrated cement paste, T11 with embedded CNT (T11 + CNT), and T11 with both CNT and CMC (T11 + CNT + CMC). All models were first equilibrated to obtain stable and low-energy configurations. Subsequently, three types of loading conditions were applied to investigate mechanical and physical properties: tension, compression, and heating. Under mechanical loading, both the stress–strain response and the resulting piezoelectric effect were analyzed. Under thermal loading, the focus was on thermally induced polarization. The simulation was used to elucidate the role of CNTs and polymer modification (CMC) at the atomistic scale. Full article

In the severely cold regions of northern China, large-scale clean heating retrofits in rural areas face critical problems, including substandard indoor thermal environments, excessive energy consumption, and prohibitive operating costs. To address these challenges, this study focuses on rural residences in Hohhot as the research subject. Field measurements were conducted throughout the heating season in a typical rural house in Hohhot, a representative city with severe cold weather, to collect indoor/outdoor thermal parameters and real-time operational data of an air-source heat pump (ASHP). A dynamic simulation platform was established using TRNSYS 18. The optimization scheme integrates passive envelope retrofitting (ground insulation improvement and energy-efficient windows) with the active optimized control of the ASHP system. Indoor thermal comfort was evaluated using the Predicted Mean Vote (PMV) index. The results show that the ASHP exhibits excellent heating effectiveness and economic viability, making it the preferred technology for rural residences in Hohhot and similar regions. After implementing the active–passive scheme, the proportion of time with comfortable indoor conditions in rural houses surges from 34.1% to 84.1%, while during the severe cold period, this proportion increases from 16.97% to 61%. The indoor thermal comfort index shifts from its previous state to the baseline comfort range of −1.0 to 0. The total heating energy consumption decreased from 18,646 kWh to 15,861 kWh, and the seasonal operating cost dropped from 3207 to 2579.3 RMB, achieving an overall reduction of 19.6% in both energy and costs. The proposed active–passive synergistic optimization scheme simultaneously improves the indoor thermal environment and reduces heating energy consumption, overcoming the limitations of single-measure retrofits. This study fills the research gap on the quantitative evaluation of active–passive synergy for rural clean heating in severely cold regions, providing a theoretical basis and technical support for clean heating retrofits in Hohhot and Inner Mongolia, facilitating low-carbon and efficient rural clean heating in northern China. Full article

To reduce adverse environmental impacts and boost renewable energy utilization, energy pile technology bridges traditional energy systems and building structures, offering an innovative route for urban low-carbonization. Currently, research on energy piles is confined to conventional non-saline soil, with insufficient exploration of their heat transfer performance in saline soil. Thus, this paper studies the latter based on prior non-saline soil research. The heat transfer performance of pile groups is analyzed in COMSOL Multiphysics by varying the pile diameters, spacing, configurations, and numbers. The findings show that the central pile undergoes the most significant thermal interference, with its water temperature on the 30th day being 1.26 °C higher than that of a single pile. A pile spacing equal to four times the diameter greatly reduces thermal interference, and a spacing of six times the diameter renders the accumulated heat effect insignificant. Additionally, a plum-shaped pile arrangement reduces energy pile group interference effectively, with higher heat transfer capacity than the traditional square arrangement. Increasing pile diameter only benefits heat transfer greatly in the first 10 days, as thermal interference offsets the advantage of expanded heat transfer area from larger diameters. Full article

To elucidate the combustion behavior and molecular-scale reaction mechanisms of Fushun oil shale kerogen under oxy-fuel atmospheres, ReaxFF molecular dynamics simulations were performed based on a previously constructed kerogen model. Five reaction systems were established: 21% O₂/79% N₂, 21% O₂/79% CO₂, 35% O₂/65% CO₂, 55% O₂/45% CO₂, and 75% O₂/25% CO₂. Under programmed heating, the evolution of chemical bonds, gaseous products, char, tar and gas transformation, and system potential energy was systematically analyzed. The results show that, at the same O₂ concentration, CO₂ delays low-temperature oxidation, shifting C–C and C–H bond cleavage and O₂ consumption to higher temperatures. At elevated temperatures, however, CO₂-related pathways promote carbon skeleton fragmentation and CO formation. Increasing O₂ concentration from 21% to 75% advances O₂ participation and H₂O formation, suppresses low-temperature CO accumulation, accelerates char consumption, and drives the system toward complete oxidation dominated by small-molecule gases. Potential energy analysis further indicates that higher O₂ concentrations advance the intense exothermic oxidation stage. A four-stage oxy-fuel combustion mechanism is proposed, providing molecular-level insight into the coupled effects of CO₂ and O₂ concentration. Full article

This perspective focuses on the field of solid waste recovery and resource utilization for end-of-life (EoL) wind turbine blades. Wind energy plays a central role in the global transition toward low-carbon energy systems owing to its technological maturity, scalability, and widespread resource availability. As global installed wind power capacity exceeded 1000 GW in 2024, improving the life-cycle energy efficiency and resource productivity of wind energy systems has become increasingly important. In this context, wind turbine blades (WTBs), the most material-intensive components with high embodied energy, are approaching large-scale end-of-life replacement, with global EoL blade waste projected to reach 2–4 million tons by 2030. Although blades may reach the end of their structural service life, they contain substantial quantities of reinforcing fibers and polymeric matrices that embody significant material and manufacturing energy. Integrating blade recycling into the wind energy value chain represents a critical opportunity to reduce dependence on energy-intensive virgin materials and lower life-cycle energy consumption and associated carbon emissions. However, the realization of energy-efficient circular utilization remains constrained by several challenges, including inefficient heat and mass transfer during blade depolymerization, limited valorization of resin-derived products, and performance degradation of recovered fibers. This perspective examines the material characteristics of blades from a life-cycle energy utilization standpoint, assesses existing recycling pathways, and identifies key technological and system-level bottlenecks. Emphasis is placed on process intensification, product upgrading, and design-for-circularity strategies to support the long-term sustainability of wind power systems. Full article