Search Results (82)

Escalating climate change and the increasing frequency of weather extremes pose a threat to the resilience of urban environments and human health, highlighting the urgent need for implementing energy-efficient interventions and reducing building cooling loads. This study investigates the passive building envelope retrofit technologies of external shading, electrochromic windows, and thermochromic windows through a multi-criteria evaluation analysis based on energy savings, economic performance, and indoor thermal comfort improvement. Thermochromic windows are discerned by a mean colour transition temperature of 34 °C and operate throughout the entire year, while electrochromic windows are activated only during cooling periods. Both technologies present total solar transmittance indices of 72.6% and 8.4% in the bleached and tinted state, respectively. External shading devices are either static or movable, applied with an inclination angle, and are either standalone interventions or combined with chromogenic glazing. Eight retrofit scenarios are investigated for a single-story, fully electrified residential building in Athens, Greece. The building features south- and east-oriented windows, which is an appropriate case to assess the effectiveness of these passive envelope cooling technologies in regulating solar heat gains. Thermal comfort is assessed using Fanger’s PMV (predicted mean vote) and PPD (Predicted Percentage of Dissatisfied) indices. The combination of electrochromic windows and movable external shading yields the highest annual electricity savings at 22.2% and reduces the PPD by 15.8%. Local static shading, on the other hand, ranks as the optimal retrofit solution in terms of economic performance, with a life-cycle cost of €6378, a 9.3% improvement in thermal comfort, and a corresponding reduction of 626 thermal discomfort hours. While the proposed multi-criteria framework can be applied to other buildings and climates, the quantitative results reported here are linked to the specific case examined: a residential building with south- and east-facing glazing in Athens, Greece, representing Mediterranean climatic conditions. Full article

Ice accretion along aircraft leading edges, particularly at stagnation line parting strips, remains difficult to remove using conventional electrothermal anti-icing systems. These systems require continuous high-power heating to maintain the stagnation region above the melting point, often exceeding 10–12 kW/m². This study introduces an Ice Cavitation Deicer (ICD) that removes ice through rapid, localized cavitation generated within a thin melt layer formed at the ice–surface interface. In the proposed approach, a short pulse of electric current melts a 1–10 µm interfacial layer and causes a cavitation impulse of approximately 1–10 MPa. This impulse ejects the stagnation-line ice in a direction normal to the surface, often against the external airflow, enabling the immediate aerodynamic removal of the remaining ice. Analytical modeling based on the energy conservation principle was used to determine the optimal foil geometry, thermal pulse parameters, thermal stress, and material selection. Experiments with various metallic foils and substrate materials validated the predicted ejection behavior. The impulses were sufficient to fracture and eject ice 1–10 mm thick. The observed ice fragment velocities varied from 1 m/s to 10 m/s. Compared with conventional thermal anti-icing, the ICD concept reduces power consumption by approximately two orders of magnitude while offering rapid and reliable leading-edge deicing. The low power requirements, rapid response, and compatibility with thin-foil heater architectures make ICD a promising technology for both conventional and electrified aircrafts, UAVs, rotorcrafts, and other platforms where power availability is limited. This manuscript presents the first theoretical and experimental research on the ICD method and is a concept-proof work. Further research and development are required before the ICD is ready to be tested in flight. Full article

The optimal control of sustainable energy supply systems, including renewable energies and energy storage, takes a central role in the decarbonization of industrial systems. However, the use of fluctuating renewable energies leads to fluctuations in energy generation and requires a suitable control strategy for the complex systems in order to ensure energy supply. In this paper, we consider an electrified power-to-heat system which is designed to supply heat in the form of superheated steam for industrial processes. The system consists of a high-temperature heat pump for heat supply, a wind turbine for power generation, a sensible thermal energy storage for storing excess heat, and a steam generator for providing steam. If the system’s energy demand cannot be covered by electricity from the wind turbine, additional electricity must be purchased from the power grid. For this system, we investigate the cost-optimal operation, aiming to minimize the electricity cost from the grid by a suitable system control depending on the available wind power and the amount of stored thermal energy. This is a decision-making problem under uncertainty regarding the future prices for electricity from the grid and the future generation of wind power. The resulting stochastic optimal control problem is treated as finite-horizon Markov decision process for a multi-dimensional controlled state process. We first consider the classical backward recursion technique for solving the associated dynamic programming equation for the value function and compute the optimal decision rule. Since that approach suffers from the curse of dimensionality, we also apply reinforcement learning techniques, namely Q-learning, that are able to provide a good approximate solution to the optimization problem within reasonable time. Full article

The revised Energy Performance of Buildings Directive (EPBD) has introduced ambitious targets aimed at accelerating the decarbonization of the building sector. In parallel, the forthcoming implementation of the Emission Trading System for buildings and road transport (ETS2) in January 2027 adds a further dimension to the policy landscape. This study investigates three renewable energy retrofit strategies (Scenarios A, B, and C) for a hotel building in northern Italy, assessing their effectiveness in meeting the decarbonization objectives set by the EPBD and ETS2. Scenario A couples photovoltaic generation with an existing gas boiler, Scenario B integrates PV with an electric heat pump for space heating, and Scenario C implements the full electrification of both heating and domestic hot water. The results of the three scenarios are evaluated using selected metrics, such as renewable primary energy consumption (EPren), non-renewable primary energy consumption (EPnren), CO₂ emission (CO₂), carbon avoidance cost (CAC), levelized cost of energy (LCOE), net present value (NPV), and Emission Trading System (ETS)2. The results show that PV deployment alone provides economic benefits but yields limited reductions in CO₂ emissions and non-renewable primary energy consumption due to continued reliance on natural gas. The introduction of a heat pump significantly enhances environmental performance, with reduced fossil fuel consumption, increased renewable energy use, and improved cost-effectiveness of carbon avoidance. The ETS2 has no impact in the case of full electrification, as fossil fuel consumption is completely eliminated. Full electrification achieves the greatest emission reductions and the lowest non-renewable primary energy demand while offering the strongest long-term economic performance. Overall, the analysis demonstrates that combining PV systems with building electrification is essential to achieving deep decarbonization, and that fully electrified configurations present the most robust pathway for compliance with emerging ETS2 policies. Full article

An efficient thermal management system (TMS) is essential for ensuring hybrid-electric aircraft (HEA) can handle the significant heat rejection required by electrified propulsion. This paper presents a system-level analysis of a compact P2PL TMS for a 1.4 MW battery generating a 70 kW heat load. A modular modeling method was used to size the key components, and then dynamic simulations were conducted under varying environmental conditions. The results indicate that a compact TMS weighing 22 kg can be developed, with a condenser heat transfer area of 26.20 m² and operating with a refrigerant mass flow rate of 0.56 kg/s while maintaining low pump power consumption at 22 W. This system can successfully regulate a battery’s temperature so that it remains below 40 °C in both standard (15 °C) and cold (−20 °C) environments. Pressure analysis confirmed the system’s flexibility and its ability to control battery temperature between 27 °C and 38 °C by adjusting the working pressure (6–8 bar). Furthermore, under hot day conditions (40 °C), battery temperature can be maintained at 47.6 °C. Even under extreme conditions (50 °C), the TMS limits the temperature to 57.45 °C, ensuring it stays within the safe operating range. Full article

Recent global efforts to produce lightweight electrified vehicles have motivated the push toward advanced lightweight materials which led to the creation of novel alloys optimized for use in high-pressure die casting (HPDC). HPDC enables the fabrication of near-net-shape automotive parts, significantly reducing or eliminating additional machining steps. A key feature of HPDC is the extremely fast cooling that forces the alloy to solidify within only a few seconds. Because of these rapid cooling conditions, it becomes essential to accurately evaluate the thermophysical behavior of newly designed lightweight alloys during severe quenching. Precisely quantifying these material properties is crucial for properly controlling HPDC operations and for building reliable numerical models that simulate filling and solidification. The thermophysical characteristics of such alloys vary markedly with temperature, especially when the material undergoes the fast solidification typical of HPDC. Therefore, understanding how these properties change with temperature during intense cooling becomes a critical requirement in alloy development. To address this need, a dedicated experimental system was designed to solidify molten metal samples under controlled and variable cooling conditions by applying multiple impinging water jets. An inverse heat-transfer algorithm was formulated to extract temperature-dependent thermal conductivity and diffusivity of the alloy as it solidifies under rapid cooling. To verify the reliability of both the inverse model and the measurements, experiments were performed using pure Tin, a reference material with well-documented thermophysical properties. The computed thermophysical properties of Tin were benchmarked against values reported in the literature and demonstrated reasonable consistency, with a maximum deviation of 13.6%. Full article

The decarbonisation of energy-intensive separation processes is critical for achieving net-zero goals in the chemical industry. While widely used for separating azeotropic mixtures, pressure swing distillation (PSD) remains highly energy-intensive due to significant thermal demands. This work presents a comprehensive systems-based assessment of electrified distillation designs, with a specific focus on tetrahydrofuran–water separation as a case study. Using Aspen Plus and Aspen Plus Dynamics, key performance indicators, including controllability, thermal and exergy efficiencies, and CO₂ emissions reduction potential, are evaluated. The electrified configurations employed heat pumps as substitutes for conventional steam heating. Disturbance rejection was applied to compare the input–output pairings and select pairings with the best controllability and disturbance rejection indices. Results showed that the conventional PSD (CPSD) exhibited higher Morari Resiliency Index (MRI) and acceptable Condition Number (CN) values, indicating better robustness and disturbance rejection than the heat pump-assisted PSD (HPAPSD). Despite this, HPAPSD achieved a 59% reduction in primary energy demand, a 23% increase in exergy efficiency, and an 82% reduction in CO₂ emissions. This study demonstrates the potential of electrification to transform PSD systems from rigid, energy-intensive operations into flexible and sustainable processes. The findings support a shift towards integrated, systems-driven design strategies in chemical separation, aligning with broader goals in process electrification, circularity, and net-zero manufacturing. Full article

Green hydrogen is a potential enabler of deep decarbonisation for industrial process heat. We assess its role in Aotearoa New Zealand using a bottom-up, least-cost energy-system model based on the integrated MARKAL-EFOM system (TIMES), which includes hydrogen production electrolysis, storage, and delivery of end-use technologies for process heat, as well as alternative low-carbon options. Drawing on detailed data on industrial energy use by sector and temperature band, we simulate pathways to 2050 under varying assumptions for electrolyser and fuel prices, technology efficiencies, electricity decarbonisation and carbon prices. In most scenarios, the least-cost pathway involves widespread electrification of low- and medium-temperature heat, with green hydrogen playing a targeted role where high-temperature requirements and process constraints limit direct electrification. Sensitivity analysis reveals that hydrogen uptake increases under higher carbon prices, lower electrolyser capital expenditure, and when grid connection or peak capacity constraints are binding. These results suggest that policy should prioritise rapid industrial electrification while focusing hydrogen support on hard-to-electrify, high-temperature processes, such as primary metals and mineral products, alongside enabling infrastructure and standards for hydrogen production, transport, and storage. Full article

The transition to electric aircraft for zero-emission transport requires integrating thermal management systems for high-performance batteries without incurring significant weight, balance, or aerodynamic penalties. This study focuses on the aerodynamic penalties associated with air-cooling systems that can compound the presently unavoidable reduction in endurance imposed by current battery energy density limitations. Building on previous research into battery installation layouts and internal cooling flows, this study is the first to investigate the lift-to-drag (L/D) optimisation for the multiple wing-mounted inlets and outlets necessary for air-cooling batteries in the wing of an electrified aircraft. Wing leading-edge inlets and NACA (National Advisory Committee for Aeronautics) ducts were analysed by systematically varying their layout, number, and dimensions. The analysis evaluated their effects on the wing’s lift, drag, and moment to maximise the L/D. Multiple highly efficient simulation test designs were developed to screen for the main factors to identify the best inlet and outlet configuration, resulting in 66 different Computational Fluid Dynamics (CFD) simulations in Ansys Fluent. Following this, three CFD verification cases of the best configuration were conducted to verify the cooling effect by combining both internal and external flow simulations with heat generation. Compared to the baseline wing of the carbon combustion aircraft, the best configuration caused a 1.75% reduction in L/D, range, and endurance. While the aerodynamic penalty is now minimised, the internal battery pack layout requires further optimisation to re-establish uniform cooling across the battery pack. Designers may still be able to separate the CFD analysis of the internal and external flow regimes with idealised inlets and outlets; however, more whole-field CFD iterations are needed to guide such subdivision to a viable and safe design for wing-mounted batteries. Further, the margins are such that wing-mounted electrification warrants careful instrumented validation in an aircraft. These findings provide crucial design guidance for sustainable aviation, particularly to enable after-market electrification projects. Full article

The transition to sustainable urban mobility requires innovative solutions optimising electric vehicle (EV) ecosystems while integrating seamlessly with smart urban grids. This paper proposes a decentralised framework leveraging adaptive algorithms, vehicle-to-grid (V2G) technology, and renewable energy prioritisation to enhance urban sustainability without requiring new infrastructure. By integrating federated learning (FL) for privacy-preserving coordination, multi-objective optimisation for load balancing, and predictive models for renewable energy integration, our approach addresses energy demand, grid stability, and environmental impact in urban areas. Validated through simulations on an IEEE 39-bus urban feeder and real-world urban mobility case studies, the framework achieves a 40% reduction in carbon emissions, improves grid reliability by 20%, and enhances renewable utilisation by 25% compared to an uncoordinated charging baseline. These outcomes support urban planning by informing smart grid design, reducing urban heat island effects, and promoting equitable mobility access. This work provides actionable strategies for policymakers, urban planners, and energy providers to advance more sustainable, electrified urban ecosystems. Full article

Buildings with electrified heat pump systems, onsite photovoltaic (PV) generation, and energy storage offer strong potential for demand flexibility. This study compares two storage configurations, thermal energy storage (TES) and battery energy storage (BESS), to evaluate their impact on cooling performance and cost savings. A Model Predictive Control (MPC) framework was developed to optimize system operations, aiming to minimize costs while maintaining occupant comfort. Results show that both configurations achieve substantial savings relative to a baseline. The TES system reduces daily operating costs by about 50%, while the BESS nearly eliminates them (over 90% reduction) and cuts grid electricity use by more than 65%. The BESS achieves superior performance because it can serve both the controllable heating, ventilation, and air conditioning (HVAC) system and the home’s broader electrical loads, thereby maximizing PV self-consumption. In contrast, the TES primarily influences the thermal load. These findings highlight that the choice between thermal and electrical storage greatly affects system outcomes. While the BESS provides a more comprehensive solution for whole-home energy management by addressing all electrical demands, further techno-economic evaluation is needed to assess the long-term feasibility and trade-offs of each configuration. Full article

Electrified powertrains in the transportation sector have increased significantly in recent years, thanks to the need for decarbonization of the on-the-road transport means. However, management of powertrains still deserves particular attention to assess necessary improvements for reducing electric consumption and increasing the mileage of the vehicles. In this regard, electric motor cooling is essential for maintaining optimal performance and longevity. In fact, as electric motors operate, they generate heat due to electric and magnetic phenomena as well as mechanical friction. If not properly managed, this heat can lead to decreased efficiency, accelerated wear, or even failure of critical components. Effective cooling systems ensure that the motor runs within its ideal temperature range, reducing the occurrence of the mentioned concerns. This improves operational reliability and, at the same time, contributes to energy savings and reduced maintenance costs over the components’ life. In this study, the cooling of the rotor of a 130-kW electric motor via refrigerating fluid circulating inside the shaft has been investigated. Two configurations of fluid passages have been considered: a direct-through flow crossing the shaft along its axis and a hollow shaft with recirculating flow, with three types of rotating helical configurations at different pitches. The benefits when using nanofluids as a cooling medium have also been evaluated to enhance the heat transfer coefficient and decrease temperature values. Compared with the baseline configuration using standard fluids (water), the proposed solution employing nanofluids demonstrates effectiveness in terms of heat transfer coefficients (up to 28% higher than pure water), with limited impact on pressure losses, thus reducing rotor temperature by up to 30 K with respect to the baseline. This study opens the possibility of integrating the cooling of the rotor with whole electric motor cooling for electric and hybrid powertrains. Full article

As part of recent measures to combat global warming, automobiles are required to be electrified and their weight reduced, leading to the advancement of multi-material structures that include aluminum alloys and aluminum die castings. Conventional fusion welding methods for joining aluminum alloys and steel materials have poor joining performance due to differences in thermal conductivity between the materials and the presence of oxide films. Friction stir welding (FSW) has been attracting attention in recent years because it is a solid-phase joining method and can also be used to join dissimilar materials. In this study, FSW overlay joints were fabricated: Aluminum alloy AA6111 was used for the upper plate, AA6061 was used for the lower plate. Non-destructive testing was performed on each joint to instantly inspect and visualize joint defects. In the case of FSW joints, no difference was observed in the heat transfer process when the joints were heated directly, but the location of the hooking could be identified by heating from a distance from the joints. The results of the analysis of the temperature change at the defect location showed a difference in heat propagation. Full article

The world’s energy system faces major challenges due to transitions from fossil fuels to other alternatives. An important part of the transition is energy-efficient homes that partially produce their own electricity. This paper explores the energy interactions between heating, cooling, and electricity usage in a planned residential area in Sweden where a significant portion of the electricity is generated by solar PV systems. Conventional district heating and cooling systems and a low-temperature district heating system that uses return cascading technology were compared with heat pump systems. Electricity sharing in an energy community has a low impact on the calculated national energy efficiency metric. It is also shown that electrifying space heating with heat pumps improves the calculated energy efficiency metric, but heat pumps increase the peak power demand in the winter due to high heat demand and a lack of solar production. Using heat pumps for heating domestic hot water and compressor chillers for cooling offers a more balanced use/production of electricity since the electric cooling load is mostly met by local solar production, as shown by an increase in self-consumption of 8% and stable self-sufficiency. There is, however, a time mismatch between production and the peak electricity demand, which could be addressed by using energy storage systems. Full article

Industrial processes such as cement, steel, and glass manufacturing rely heavily on fossil fuels for high-temperature heat, presenting a significant challenge for decarbonization. To enable continuous thermal output from intermittent renewable electricity, Electrified Thermal Solutions, Inc. is developing the Joule Hive™ Thermal Battery (JHTB), an electrically heated energy storage system capable of delivering process heat up to 1800 °C. The system employs electrically conductive firebricks (E-Bricks) as both heating elements and thermal storage media, arranged with insulating bricks (I-Bricks) to facilitate gas flow and heat exchange. The work combines experimental and numerical studies to evaluate the thermal, electrical, and structural performance of the JHTB. A small-scale charging experiment was conducted on a single E-Brick circuit in a 1500 °C furnace, showing good agreement with coupled thermal-electric finite element models that account for Joule heating, temperature-dependent properties, radiation, and natural convection. Structural modeling assessed stress induced by thermal gradients. In addition, a high-fidelity conjugate heat transfer model of the full JHTB core was developed to assess system-scale discharge performance, solving conservation equations with SST k-ω turbulence and radiation models. Simulations for two air channel geometries demonstrated the battery’s ability to deliver 5 MW of heat for at least five hours with air temperatures higher than 1000 °C, validating its potential for industrial decarbonization. Full article