Abstract

Rising global temperatures have intensified the need to reduce energy consumption in the built environment. Passive cooling measures, such as cooling paints and films, can mitigate indoor overheating by reflecting solar radiation. While their capabilities have been demonstrated particularly in tropical climates, their effectiveness in Mediterranean regions remains underexplored. Through building simulations conducted in the software IES VE, this paper evaluates the performance of cooling paints using historical weather data of Mediterranean locations. Results indicate that these paints can reduce annual average indoor temperatures by 1.98 ± 0.86 °C, contributing to improved thermal comfort and reduced cooling demand. These findings showcase the potential of cooling paints as a promising passive strategy to enhance building energy performance, particularly in countries facing elevated and prolonged heat events.

Abstract

Rising summer temperatures in the UK, alongside stricter building regulations on thermal efficiency, are increasing the importance of residential cooling demand. While very few households currently use active cooling, adoption is expected to grow, placing additional pressure on electricity networks. This paper presents a study combining physics-based modelling with machine learning to forecast building thermal demand using basic dwelling characteristics and weather data. Results show that the method achieves high accuracy in predicting the thermal demand of previously unseen dwellings—showcasing the potential extreme gradient boosting may have in forecasting cooling demand in a warming world.

Abstract

Perfluorosulfonicacid (PFSA) membranes limit proton exchange membrane fuel cells (PEMFCs) to stable operation at elevated temperatures due to inadequate water retention. This study, a combination of simulations and experiments are employed to address this limitation. A 5 kW fuel cell (FC) stack tested up to 105 °C showed decreased performance at higher temperatures, offset by increased pressure—consistent with simulations. Under optimized conditions, it maintained an average voltage of 0.668 V at 1.8 A/cm² with voltage fluctuations under 5 mV over an hour, although voltage oscillations occurred at higher current densities. The study clarifies PEMFC behavior at high temperatures and suggests directions for future research.

Abstract

Distributed photovoltaic (DPV) power generation has increasingly emerged as one of the most promising renewable energy sources due to its extensive distribution and flexible installation. However, its output is highly influenced by solar irradiation conditions, exhibiting diurnal and seasonal variations, with weather conditions being the most significant influencing factor. To ensure the secure and stable operation of the power system and maintain an appropriate balance between supply and demand, predicting DPV power output presents a viable solution. This paper proposes an improved KMC-Vine Copula model for probabilistic prediction of DPV power by integrating spatio-temporal influencing factors and the prediction results of centralized PV power. Using copula correlation theory, the spatio-temporal dependencies between centralized and distributed PV systems are figured out. Conventional single copula functions are inadequate in capturing complex correlations. Thus, an optimized copula model is introduced to address the above limitation. However, due to its inability to represent high-dimensional dependencies, a flexible Vine Copula model is constructed as the final prediction framework. Through the case study, compared with the optimized copula model, the proposed model improved by 26.87% (interval width), 41.6% (reliability), and 39.23% (sharpness), respectively, under three evaluation indexes.

Abstract

To address the challenges of nonlinearity, non-stationarity, and multimodal fusion in power load forecasting under the new power system environment, this paper proposes a load forecasting method based on large language models that considers the separation of numerical and textual data. The method constructs a dual-channel architecture for numerical and textual separation processing, using a frozen large language model encoder to extract textual features and a multi-layer perceptron (MLP) to extract numerical features. After feature concatenation, the input is fed into the frozen large language model decoder, and the results are finally output through a numerical prediction head. By freezing the core weights of the large language model and introducing only a small number of trainable layers, the method retains the model’s strong semantic understanding capability while reducing computational overhead. A case study based on real load data from a large city in northern China demonstrates that the proposed NTSForecast method outperforms mainstream time series forecasting models such as Informer, Autoformer, and PatchTST in various evaluation metrics, including mean square error (MSE) and mean absolute error (MAE), validating the effectiveness and superiority of this method.

Abstract

The study experimentally examines the influence of outlet-manifold on the thermal performanceand thereby the energy efficiencyof a two-phase jet-impingement cooling system using HFE-7000 as the working fluid, enabling more effective energy utilization in high-heat-flux applications. The test section features a fixed 3×16 jet array with a jet diameter of 1.5 mm and a jet-to-jet pitch of 2.5 mm. A comparative analysis is conducted between a symmetric double outlet manifold and a more compact single outlet (side-in/side-out) configuration, highlighting design choices that optimize energy transfer rates. Results demonstrate that the double-outlet design yields superior heat transfer performance across the operating range, exhibiting a consistently lower wall superheat at a given heat flux and a reduced thermal resistance, which collectively contribute to lower overall energy demands for cooling. A significant enhancement in critical heat flux (CHF) was observed, with the double-outlet manifold achieving 53 W/cm², compared to 29.1 W/cm² for the single-outlet design at a mass flux of 78 kg/m²·s, allowing for sustained high-power operationwith minimized energy penalties. The lowest recorded thermal resistances were 0.036 °C/W for both manifold types, though the dual-outlet design sustained this performance over a broader range, promoting broader energy-efficient deployment. Furthermore, the study examines the impact of manifold design on temperature uniformity across the heated surface, revealing that the outlet configuration plays a critical role in mitigating temperaturegradients and ensuring equitable energy distribution in thermal management systems.

Abstract

This study investigates the effect of heat transfer tube configurations on the thermal performance of latent heat thermal energy storage systems operating under simultaneous charging and discharging conditions. A two-dimensional numerical model was developed using the enthalpy-porosity method to simulate melting and solidification of phase change material. Four tube arrangements, comprising two charging and two discharging tubes, were analyzed to evaluate their impact on melting/solidification progression and heat flux variation. Results indicate that tube placement significantly influences natural convection within the PCM, thereby affecting energy transfer rates. Case 4 shows the highest initial charging heat flux due to enhanced early convection, but Case 2 sustains the highest long-term fluxes during both charging (1000 W/m²) and discharging (900 W/m²). Case 3 consistently demonstrates poor performance, highlighting unfavorable flow pathways. Overall, Case 2 emerges as the most effective configuration, offering an optimal balance between charging and discharging performance. These findings highlights the importance of tube geometry in designing high-efficiency LHTES units for continuous energy supply applications.

Abstract

The boiling heat transfer characteristics of saline solutions, exemplified by seawater, play a critical role in the operational safety of industrial equipment. A clear understanding of the influence of salt concentration on heat transfer performance is therefore essential. In this study, pool boiling experiments were conducted using deionized water and saline solutions with concentrations of 1%, 3.5%, and 6% over a heat flux range of 20–200 kW/m². Two types of heating surfaces were employed: a plainand a structured pin-fin stainless steel surface.The results demonstrate that heat transfer performance deteriorates in saline solutions on both surfaces compared to deionized water. However, when the salt concentration exceeds 3.5%, further increases have a negligible impact on heat transfer. The wall superheat required for the onset of nucleate boiling (ONB) was found to increase with salt concentration: recorded as 7.01K for pure water and 18.45K for the 6% saline solutionat plain surface.Compared to the plainsurface, the pin-fin surfacefeaturing a width-depth-pitch configuration of 500 μmsignificantly alleviated heat transfer degradation and reduced the wall superheat required for nucleation.

Abstract

Lithium-ion batteries inevitably experience global mechanical loading during service, which significantly affects the electrode-separator interfacial contact, leading to spatial heterogeneity in current density and reaction overpotential. These effects can promote localized onset of lithium plating at the graphite anode, especially under low-temperature conditions. Lithium plating not only accelerates capacity fade and shortens cycle life, but the resultant dendrites may also pierce the separator, causing internal short circuits and potential safety hazards. In this work, using a wound NCM811/graphite pouch cell as a representative case, we combine numerical simulation with experimental characterization to systematically investigate the spatial heterogeneity of lithium plating on the graphite anode across different levels of global mechanical loading. The results reveal that global mechanical load preferentially compacts the wound region, significantly reducing separator porosity and electrolyte transport capability, thereby increasing ionic resistance and diffusion limitation. These findings elucidate the mechanical-electrochemical mechanisms governing lithium plating and provide a theoretical basis for optimizing cell structural design, stack-pressure strategies and the prevention of lithium-plating-induced safety risks in lithium-ion batteries.

Abstract

The concept of low-amplitude structures, also known as micro-amplitude structures and micro-structures, generally refers to reservoirs with an oil-bearing height of less than 10m. Low-amplitude structures are generally likely to obtain industrial oil flows and have good exploration prospects. Artificial edge-water flooding, recently developed by Shengli Oilfield, serves as a water flooding alternative for enhancing oil recovery in complex fault-block reservoirs during the ultra-high water-cut stage. While this technology has demonstrated favorable field application results, its efficacy in low-amplitude structural reservoirs warrants further investigation. The C1 Block in Shengli Oilfield has long vertical oil-bearing well sections, multiple layered systems, and low structural amplitude. This study employs theoretical analysis, numerical simulation, and dynamic performance evaluation to examine artificial edge-water flooding in the medium-permeability, low-amplitude reservoir of the C1 Block. The findings reveal that low-amplitude structures exert significant control over the original distribution and enrichment of oil and water. A multi-factor indicator system was applied to subdivide the reservoir vertically into four distinct layer series for development. Investigations into influencing factors of the artificial edge-water flooding process have identified key directions for future reservoir management strategies.