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Lithium-ion battery packs are made by many batteries, and the difficulty in heat transfer can cause many safety issues. It is important to evaluate thermal performance of a battery pack in designing process. Here, a multiscale method combining a pseudo-two-dimensional model of individual battery and three-dimensional computational fluid dynamics is employed to describe heat generation and transfer in a battery pack. The effect of battery arrangement on the thermal performance of battery packs is investigated. We discuss the air-cooling effect of the pack with four battery arrangements which include one square arrangement, one stagger arrangement and two trapezoid arrangements. In addition, the air-cooling strategy is studied by observing temperature distribution of the battery pack. It is found that the square arrangement is the structure with the best air-cooling effect, and the cooling effect is best when the cold air inlet is at the top of the battery pack. We hope that this work can provide theoretical guidance for thermal management of lithium-ion battery packs. [ABSTRACT FROM AUTHOR]

• Employing the combinations of short- and long-duration energy storage is assessed. • Equipping with both batteries and thermal energy storage outperforms in economy. • Integrating concentrated solar power is advised in good solar resource regions. • Hydrogen storage demonstrates reduced energy waste under high reliability. • The optimal system combination is influenced by the maximum capacity limits. Renewable energy generation systems typically exhibit variable output. The integration of short- and long-duration energy storage systems is the strategy to reconcile the discrepancy between renewable energy generation and load demand. This investigation aims to evaluate the feasibility of utilizing combinations of short- and long-duration energy storage under diverse conditions. The study involves energy generation systems incorporating photovoltaic arrays, wind turbines, batteries, hydrogen storage, thermal energy storage, and concentrated solar power components. The analysis covers 12 distinct regions within China, each paired with two distinctive demand profiles. The optimal capacity for each system's components was determined to minimize the levelized cost of energy (LCOE) while maintaining a loss of power supply probability (LPSP) of 1 %. Subsequently, the energy waste and environmental performance of the optimized system were examined. Additionally, the impact of maximum component capacity limitations on the optimal system configuration was investigated. Results indicate that systems equipped with both batteries and thermal energy storage outperform those paired with batteries and hydrogen storage in terms of economic performance under the LPSP of 1 % constraint. Moreover, the inclusion of a concentrated solar field proves to be economical in regions with ample solar resources. When calibrated to capacities that yield minimal LCOE while ensuring exceptional power supply reliability, the benefits of reducing energy waste with a battery and hydrogen storage configuration become pronounced. For installations where the capacity of generation components does not exceed 600 MW, a system integrating battery and hydrogen storage demonstrates superior economic performance in regions with abundant wind resources. [ABSTRACT FROM AUTHOR]

Battery fault diagnosis is essential for ensuring safe and reliable operation of electric vehicles. In this article, a novel battery fault diagnosis method is presented by combining the long short-term memory recurrent neural network and the equivalent circuit model. The modified adaptive boosting method is utilized to improve diagnosis accuracy, and a prejudging model is employed to reduce computational time and improve diagnosis reliability. Considering the influence of the driver behavior on battery systems, the proposed scheme is able to achieve potential failure risk assessment and accordingly to issue early thermal runaway warning. A large volume of real-world operation data is acquired from the National Monitoring and Management Center for New Energy Vehicles in China to examine its robustness, reliability, and superiority. The verification results show that the proposed method can achieve accurate fault diagnosis for potential battery cell failure and precise locating of thermal runaway cells. [ABSTRACT FROM AUTHOR]

This study aims to develop a prototype for harvesting thermoelectric energy from railway track. By capturing the existing thermal energy in railway tracks, this technology helps power rail-side sensors in off-grid and remote areas without depleting natural resources. In low latitudes such as southern China, the temperature of railway tracks can reach 57 °C due to solar radiation. However, at a relatively shallow depth (200 mm), the substratum below the track foundation (e.g., soils) has a lower temperature (i.e., 15 °C–26 °C). This temperature difference can be used to generate electricity through a thermoelectric generator (TEG). The proposed approach captures thermal energy from the railway track and transfers the energy to the TEG prototype beneath the bottom of rails. Evaluation of the prototype is conducted by finite volume analysis, field test, and laboratory experiment. The results indicate that the TEG prototype can produce 5.8 mW–316.8 mW of power across a resistant load at thermal gradient from 8 °C to 29.2 °C. A DC-DC buck-booster circuit with lithium battery management is developed to charge the batteries by the harvested thermal energy. The system operates at a low startup voltage of 0.9 V and its conversion efficiency is larger than 60%. • Highlights of the paper: • A prototype was developed for harvesting thermoelectric energy from railway track. • One year temperature data of the railway track infrastructure were measured. • A DC-DC converter with lithium battery management was developed. • The system can charge a cellphone at a temperature gradient of 23.5 °C. [ABSTRACT FROM AUTHOR]

Abstract Aerogel insulating panels (AIPs) exhibit extensive prospects for application in aerospace, industry and buildings as excellent energy-saving thermal insulators owing to their ultra-low thermal conductivity. This work aims to numerically and experimentally investigate the thermal performance of AIPs in building energy efficiency. The AIPs were prepared and used as an insulation layer in an insulating cell. Three insulating cells with three different insulating materials as the insulation layer were prepared to measure and comparatively analyse their thermal performances. A resistance-capacitance thermal network model to predict the thermal performance of the insulating cells was developed and validated with the experimental data. The thermal indices of cells, i.e. the time lag, decrement factor and daily heat loss, were explored under periodic disturbances of exterior air temperature. Furthermore, the thermal performance of AIPs for exterior walls was predicted by adopting the typical wall structure in the hot summer and warm winter zone of China. The results showed that the AIP wall has decreases of ∼20% and ∼40% in the fluctuation amplitude of the internal temperature and heat flow, respectively, compared with the traditional insulating walls. Highlights • A method to indicate thermal performance of AIP for energy efficiency is proposed. • Three insulating cells with EPS, GF and AIP are prepared and compared. • AIP cell shows twice time lag, 40% less decrement factor and 35% less daily heat loss. • AIP wall has ∼20% and ∼40% decreases in amplitudes of temperature and heat flow. [ABSTRACT FROM AUTHOR]

• Beijing April 2021 BESS fire and explosion studied by CFD and simulation. • Cable trench revealed as key mode of incident propagation through transferring hot gases. • The thermal runaway gas concentration was determined based on the numerical results. • The thermal runaway gas explosion hazard in BESS was systematically studied. To further grasp the failure process and explosion hazard of battery thermal runaway gas, numerical modeling and investigation were carried out based on a severe battery fire and explosion accident in a lithium-ion battery energy storage system (LIBESS) in China. The composition and transport law of gas caused by large-scale LIB failure were theoretically analyzed, and the explosion risk of thermal runaway gas mixture in complex space after accidental ignition were systematically discussed by the computational fluid dynamics (CFD) technology. After the investigation, the underground cable trench is the key channel that causes the thermal runaway gas of lithium iron phosphate batteries to be transported to the building 20 m away and induces the explosion. After about 8500 s of battery burning, the average concentration of the thermal runaway mixed gas diffused from the cable trench is 16.4%. The arrangement of obstacles in the accident building is the main factor determining the explosion overpressure of thermal runaway gas, and the overpressure generated at the end of the obstacle path exceeds 70 kPa. Multiple windows in the battery room play an effective explosion-venting effect, but increase the damage range of outdoor high-temperature flame. In addition, the System-Theoretical Accident Model and Processes (STAMP) was used to analyze the causes of the accident, and the safety constraints that should be imposed by the three control levels of the government, functional departments and energy storage power stations were introduced to prevent battery failure and fire accidents in the BESS. The research method and analysis results will provide important ideas and reference for the investigation of fire and explosion accidents in BESS. [ABSTRACT FROM AUTHOR]

Local strong sandstorms (LSSs) in northwestern China often occur suddenly in tens of minutes during the late afternoon and by dusk. Observations and theoretical studies have shown the trigger role of cold-air pools over desert areas for the occurrence of LSS. In this study, a numerical heat convection model was established to simulate an LSS that was induced by a single cold pool with vertical helicity to study the evolution process. The Reynolds averaged Navier–Stokes (RANS) method was used for the numerical calculation to illustrate different stages of the evolution process of an LSS. Results show that after the intrusion of a cold pool into the upper region of the surface convective mixing layer, descending of the cold air would lead to the downward transport of vorticity, enabling thermal convection cells in the mixing layer to become swirling convection cells. After LSS is fully developed, there occurs many subvortices (secondary vortices) in the convection field. The velocity at different altitudes over selected positions in the calculation domain is consistent with the "lobe" shape of an LSS. The secondary vortices cause quick and huge energy dissipation and the decay of the LSS. These results are consistent with observations and indicate the crucial effect of convection cells structure in the mixing layer and the cold pool in the upper layer on the formation of LSS. [ABSTRACT FROM AUTHOR]