Applied Thermal Engineering最新文献_第8页

Impacts of low-temperature heat release on unstretched laminar burning velocity in advanced flex-fuel gasoline-ethanol engines 低温放热对先进柔性燃料汽油-乙醇发动机非拉伸层流燃烧速度的影响

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-06 DOI: 10.1016/j.applthermaleng.2024.124826

Kohei Isobe , Kei Yoshimura , Takuma Kobayashi , Ratnak Sok , Jin Kusaka

Improving brake thermal efficiency (BTE) of flex-fuel engines can contribute to decarbonizing conventional and hybridized vehicles running on spark-ignited (SI) engines. High compression ratio (CR) and burning velocity under exhaust gas recirculation (EGR) conditions can improve the engine BTE. Ethanol fuel, which has been attracting increasing attention recently, can improve brake thermal efficiency due to its high-octane number and fast laminar burning velocity (LBV). With higher CRs, low-temperature heat release (LTHR) occurs in the unburned mixture, which affects the compositions, oxidation, and in-cylinder temperature. Such thermodynamic changes on unstretched LBV have not been thoroughly investigated, especially in production-intent next-generation flex-fuel engines. This study aims to clarify the LTHR impacts on LBV under EGR conditions using ethanol-blended gasoline surrogate fuel SI engines. The testbed used a single-cylinder SI engine fueled by E0 (gasoline surrogate), E20 (20 % ethanol + 80 % E0 by volume), E40, E60, E85, and E100. Detailed chemical reaction calculations were conducted using the boundary conditions obtained from production-intent, strong-tumble flow, and flex-fuel engine experiments. This work predicted LTHR in an unburned mixture using a zero-dimensional detailed chemical reaction calculation. LBV is predicted by a 1D kinetic laminar flame code. As a result, LTHR proceeds before the main combustion. The results show that the temperature increase associated with LTHR increases the burning velocity, while the partial oxidants decrease the burning velocity. Moreover, this work examined higher CRs using detailed chemical reaction calculations, and the results show that fuels with higher ethanol blending ratios can increase LBV in the late combustion phase.

提高柔性燃料发动机的制动热效率（BTE）有助于使使用火花点火（SI）发动机的传统汽车和混合动力汽车脱碳。废气再循环（EGR）条件下的高压缩比（CR）和燃烧速度可提高发动机的制动热效率（BTE）。最近日益受到关注的乙醇燃料，因其辛烷值高和层燃速度快（LBV），可提高制动热效率。随着辛烷值的升高，未燃烧混合物中会出现低温放热（LTHR），从而影响成分、氧化和缸内温度。对未拉伸 LBV 的这种热力学变化尚未进行深入研究，特别是在具有生产意图的下一代柔性燃料发动机中。本研究旨在利用乙醇混合汽油代用燃料 SI 发动机阐明 EGR 条件下 LTHR 对 LBV 的影响。试验台使用了一台单缸 SI 发动机，其燃料包括 E0（代用汽油）、E20（20 % 乙醇 + 80 % E0（体积比））、E40、E60、E85 和 E100。利用从生产意图、强翻滚流和柔性燃料发动机实验中获得的边界条件进行了详细的化学反应计算。这项工作采用零维详细化学反应计算方法预测了未燃烧混合物中的 LTHR。LBV 由一维动力学层流火焰代码预测。因此，LTHR 在主燃烧之前进行。结果表明，与 LTHR 相关的温度升高会提高燃烧速度，而部分氧化剂会降低燃烧速度。此外，这项工作还利用详细的化学反应计算对更高的 CR 进行了研究，结果表明，乙醇混合比更高的燃料可以增加燃烧后期的 LBV。

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引用次数: 0

Validation of heat transfer models and optimization of heat shielding performance of high-temperature multilayer insulations for hypersonic vehicles 高超音速飞行器高温多层隔热材料传热模型的验证和热屏蔽性能的优化

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-06 DOI: 10.1016/j.applthermaleng.2024.124840

Kuan Wang , Jiangtao Li , Xiaoxia Hu , Shuo Yang , Chensi Zhang , Anran Guo , Haiyan Du

Multilayer insulation (MLI) is widely used in hypersonic vehicles because of its low density and excellent thermal insulation performance. However, the insulation mechanism of MLI remains poorly understood, leading to conflicting views on how to enhance its thermal insulation capabilities. In this study, two different numerical models were built and validated with experiment data to investigate key factors influencing MLI performance. The analysis focused on the effects of reflective screen positioning, the surface emissivity of reflective screens and the radiation properties parameters of fibrous materials on the thermal insulation performance of the MLI. The results show that the thermal insulation performance is better when the reflective screens are placed close to the thermal boundary. Moreover, insulation materials with lower absorption coefficients enhance the effectiveness of the reflective screens, further improving the thermal insulation performance of MLI. In addition, the study reveals that the thermal insulation mechanisms differ between the upper and lower surfaces of the reflective screens. Lower emissivity on the upper surface combined with higher emissivity on the lower surface optimizes the thermal insulation performance of MLI. These findings offer valuable insights for advancing MLI designs and improving its application in future high-speed vehicles.

多层隔热材料（MLI）因其密度低、隔热性能优异而被广泛应用于高超音速飞行器。然而，人们对多层隔热材料的隔热机理仍然知之甚少，导致在如何增强其隔热能力方面意见不一。本研究建立了两种不同的数值模型，并通过实验数据进行验证，以研究影响 MLI 性能的关键因素。分析的重点是反射屏的定位、反射屏的表面发射率和纤维材料的辐射特性参数对多层建筑隔热性能的影响。结果表明，当反射屏靠近热边界时，隔热性能更好。此外，吸收系数较低的隔热材料能增强反射屏的效果，进一步提高多层建筑的隔热性能。此外，研究还发现反射屏上下表面的隔热机理不同。上表面较低的发射率与下表面较高的发射率相结合，可优化多层绝缘的隔热性能。这些发现为推进 MLI 设计和改进其在未来高速车辆中的应用提供了宝贵的见解。

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引用次数: 0

Numerical investigation of PEMFC performance enhancement through combined design of anodic fishbone ridge groove channel and optimal gas diffusion layer porosity gradient 通过阳极鱼骨脊槽通道和最佳气体扩散层孔隙梯度的组合设计提高 PEMFC 性能的数值研究

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-06 DOI: 10.1016/j.applthermaleng.2024.124829

Guisheng Chen , Yaozhang Li , Tingjie Ba , Junwei Yang , Yaoping Li , Yinggang Shen , Renxin Xiao , Nan Pan

The flow field plate is one of the core components of proton exchange membrane fuel cells (PEMFC), and its structure significantly influences the thermo-electrochemical coupling transport characteristics of PEMFCs. Optimizing the parameters of the flow channels of bipolar plates is crucial for enhancing the mass transfer of reacting gas and improving water removal capacity. In this study, an anodal fishbone ridge groove combined flow channel (F-SFC) is designed to enhance the diffusion uniformity of anode hydrogen gas, and a 3D multi-phase model of PEMFC is established using the multiphysics simulation software COMSOL Multiphysics. The F-SFC was compared with traditional bipolar plates featuring symmetric anode and cathode flow channels in terms of overall output performance, and the results are presented. The findings indicate that the F-SFC design achieves an average increase of 28.78% in current density and 21.07% in power density compared to conventional fishbone flow channels. When compared to traditional serpentine flow channels, the F-SFC design shows a 13.5% increase in current density and a 10.42% increase in power density. Furthermore, adding multilayer porosity gradients to gas diffusion layers (GDLs) greatly improves internal mass transfer. A gradient porosity of 0.7, 0.5, and 0.3 along the Z-axis produces a more equal distribution of current density and water concentration on the membrane. This work sheds fresh light on optimizing PEMFC design for increased power density, providing useful theoretical advice for future advances.

流场板是质子交换膜燃料电池（PEMFC）的核心部件之一，其结构对 PEMFC 的热电化学耦合传输特性有重大影响。优化双极板流道的参数对于增强反应气体的传质和提高脱水能力至关重要。本研究设计了阳极鱼骨脊槽组合流道（F-SFC）以提高阳极氢气的扩散均匀性，并利用多物理场仿真软件 COMSOL Multiphysics 建立了 PEMFC 的三维多相模型。就整体输出性能而言，将 F-SFC 与具有对称阳极和阴极流道的传统双极板进行了比较，并给出了结果。研究结果表明，与传统的鱼骨流道相比，F-SFC 设计的电流密度平均提高了 28.78%，功率密度平均提高了 21.07%。与传统的蛇形流道相比，F-SFC 设计的电流密度提高了 13.5%，功率密度提高了 10.42%。此外，在气体扩散层（GDL）中加入多层孔隙梯度可大大改善内部传质。沿 Z 轴分别为 0.7、0.5 和 0.3 的梯度孔隙率使膜上的电流密度和水浓度分布更加均匀。这项研究为优化 PEMFC 设计以提高功率密度提供了新的思路，为未来的发展提供了有用的理论建议。

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引用次数: 0

Non-equilibrium condensation flow characteristics of wet steam considering condensation shock effect in the steam turbine 考虑汽轮机凝结冲击效应的湿蒸汽非平衡凝结流动特性

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-06 DOI: 10.1016/j.applthermaleng.2024.124828

Pengfei Hu , Tianbo Hou , Weifei Gu , Jie Wan , Qi Li

A non-equilibrium condensation flow occurs in steam turbines, accompanied by condensation shock. At present, there are limited studies on the influence of condensation shock on the flow and condensation characteristics of wet steam, and the unsteady influence of condensation shock on the flow field of wet steam always have been ignored. In this paper, the unsteady flow characteristics of condensation were presented by considering the condensation shock effect. First, the condensation flow models and corresponding source terms were programmed and loaded with UDS (user-defined scalar) and UDF (user-defined function), respectively, and the governing equations were discretized using a high-resolution calculation method. The calculated results agreed well with the reported experimental results. Based on the models, the non-equilibrium condensation flow characteristics with inlet and outlet pressures in Laval nozzle considering the condensation shock effect were analyzed. Finally, during the unsteady phase change process, the effects of back pressure and saturation of the inlet on the liquid phase parameters were examined considering the condensation shock effect in the Dykas cascade. The results show that a decrease in the back pressure and an increase in the inlet pressure improve the condensation shock intensity in Laval nozzle. With the increase of condensation shock intensity, the nucleation rate increases. Moreover, in Dykas cascade, with the increase of back pressure from 48.8 kPa to 73.2 kPa, the maximum wetness decreases from 4.8 % to 2.1 %, whereas with the increase of relative saturation from 0.58 to 0.88, the maximum wetness increases from 2.4 % to 3.6 %. The results obtained in this paper are of significance to accurately analyze the actual situation of non-equilibrium condensation flow of wet steam and to develop methods for reducing wet steam loss in turbine stage.

蒸汽轮机中会出现非平衡凝结流，并伴随着凝结冲击。目前，关于凝结水冲击对湿蒸汽流动和凝结特性影响的研究还很有限，凝结水冲击对湿蒸汽流场的非稳态影响一直被忽视。本文通过考虑凝结水冲击效应，提出了凝结水的非稳态流动特性。首先，用 UDS（用户自定义标量）和 UDF（用户自定义函数）分别编程并加载了凝结水流动模型和相应的源项，并采用高分辨率计算方法对控制方程进行了离散化处理。计算结果与报告的实验结果非常吻合。在模型的基础上，分析了考虑冷凝冲击效应的非平衡冷凝流动特性以及拉瓦尔喷嘴的入口和出口压力。最后，在非稳态相变过程中，考虑到 Dykas 级联中的冷凝冲击效应，研究了入口背压和饱和度对液相参数的影响。结果表明，降低背压和提高入口压力可改善拉瓦尔喷嘴的冷凝冲击强度。随着冷凝冲击强度的增加，成核率也随之增加。此外，在 Dykas 级联中，随着背压从 48.8 kPa 增加到 73.2 kPa，最大湿度从 4.8 % 下降到 2.1 %，而随着相对饱和度从 0.58 增加到 0.88，最大湿度从 2.4 % 增加到 3.6 %。本文得出的结果对于准确分析湿蒸汽非平衡凝结流的实际情况，以及开发减少汽轮机级湿蒸汽损失的方法具有重要意义。

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引用次数: 0

Effect of PTFE content on the laser-induced ignition and combustion characteristics of Al@PTFE composite fuels 聚四氟乙烯含量对 Al@PTFE 复合燃料的激光诱导点火和燃烧特性的影响

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-06 DOI: 10.1016/j.applthermaleng.2024.124773

Jiewen Xiong , Minqi Zhang , Wentao Wan , Yanbokang Shu , Shengji Li , Xuefeng Huang

This paper prepared aluminum@polytetrafluoroethylene (Al@PTFE) composite fuels with different PTFE contents and evaluated the effect of PTFE content on the thermal and combustion characteristics via multiple characterization methods. The scanning electron microscopy (SEM) and thermogravimetry–differential scanning calorimetry (TG-DSC) results showed that the PTFE was well coated on the surface, and the higher the PTFE content, the faster the oxidation reaction rate. Al@PTFE_8% fuel demonstrated more stable thermal performance and higher weight gain. Al@PTFE_15% had a weak endothermic peak at 337.2 °C, while the other two fuels did not appear. The nanosecond pulsed laser-induced plasma ignition (LIPI) test showed that compared to pure Al counterpart, Al@PTFE fuels could effectively shorten the ignition delay and promote the energy release, for Al@PTFE_8% with a reduction of 41.9% in ignition delay and an increase by 17.1 % in combustion temperature. The self-sustaining burn time decreased as the PTFE content increased. The gas-phase combustion of Al@PTFE fuels were more pronounced, and their AlO spectral signal intensity were stronger. The Al@PTFE combustion residues showed lots of cracks and holes, and the mass fraction of O was increased from 22.96 % (Al) to 30.53 % (Al@PTFE_8%). The proposed combustion mechanism reveals that PTFE destroyed the alumina film that hindered combustion, significantly promoting the combustion of Al particles. This study provides guidance for laser-induced plasma ignition of this material under ultrahigh heating rates.

本文制备了不同聚四氟乙烯含量的铝@聚四氟乙烯（Al@PTFE）复合燃料，并通过多种表征方法评估了聚四氟乙烯含量对其热性能和燃烧特性的影响。扫描电子显微镜（SEM）和热重-差示扫描量热法（TG-DSC）结果表明，聚四氟乙烯表面包覆良好，聚四氟乙烯含量越高，氧化反应速率越快。Al@PTFE_8% 燃料具有更稳定的热性能和更高的增重。Al@PTFE_15% 燃料在 337.2 °C处出现了一个微弱的内热峰，而其他两种燃料则没有出现。纳秒脉冲激光诱导等离子体点火（LIPI）试验表明，与纯铝燃料相比，Al@PTFE 燃料能有效缩短点火延迟并促进能量释放，其中 Al@PTFE_8% 燃料的点火延迟缩短了 41.9%，燃烧温度提高了 17.1%。自持燃烧时间随着 PTFE 含量的增加而缩短。Al@PTFE 燃料的气相燃烧更明显，其 AlO 光谱信号强度更强。Al@PTFE 燃烧残留物出现大量裂纹和孔洞，O 的质量分数从 22.96 %（Al）增加到 30.53 %（Al@PTFE_8%）。提出的燃烧机理表明，PTFE 破坏了阻碍燃烧的氧化铝膜，极大地促进了 Al 粒子的燃烧。这项研究为超高加热速率下激光诱导等离子体点燃这种材料提供了指导。

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引用次数: 0

Dynamic modeling of post-combustion carbon capture process based on multi-gate mixture-of-experts incorporating dual-stage attention-based encoder-decoder network 基于多门专家混合物的燃烧后碳捕获过程动态建模，其中包含基于双阶段注意力的编码器-解码器网络

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-06 DOI: 10.1016/j.applthermaleng.2024.124838

Cheng Zheng , Peng Sha , Zhengyang Mo , Zihan Tang , Meihong Wang , Xiao Wu

Solvent-based post-combustion carbon capture (PCC) technology is a promising, near-term solution for decarbonizing power generation and industrial facilities. Model-based process simulation is crucial for the optimal design and operation of the PCC process. Recently, data-driven models have gained attention due to their adaptability, efficient computation and high accuracy. However, the nonlinearity, strong couplings and multi-time scale features of the PCC process pose significant challenges for model identification. To this end, this paper proposes a multi-gate mixture-of-experts incorporating dual-stage attention-based encoder-decoder (MMoE-DAED) network for dynamic modeling of the PCC process under wide operating conditions. An encoder-decoder composed of long short-term memory (LSTM) network is employed to extract features from the time-dependent input data and learn the complex dynamic interactions caused by the inertial and delay properties of the process. Dual-stage attention mechanism is incorporated into the encoder and decoder respectively to select the most relevant input features and their correlations within the time series data. To enhance multi-output prediction accuracy, multi-gate mixture-of-experts (MMoE) framework that considers correlations of multitask learning is implemented. Simulation results using operating data from a PCC experimental setup indicate that the proposed modeling approach accurately predicts the steady-state values and dynamic trends of the CO₂ capture rate and stripper bottom temperature over a wide operating range. The RMSE, MAPE and R² indices for the CO₂ capture rate are 2.1592, 0.0295, 0.9641, respectively, and for the stripper bottom temperature are 0.1491, 0.0003, 0.9833, respectively. Validations on a PCC simulator further verify the accuracy and efficiency of the MMoE-DAED model, which enables an 80.87% reduction in computation time compared to the simulator. This paper points to a new direction for the data-driven dynamic modeling of complex energy conversion processes.

基于溶剂的燃烧后碳捕集（PCC）技术是发电和工业设施脱碳的一种前景广阔的近期解决方案。基于模型的过程模拟对于 PCC 过程的优化设计和运行至关重要。最近，数据驱动模型因其适应性强、计算效率高和准确性高而备受关注。然而，PCC 过程的非线性、强耦合和多时间尺度等特点给模型识别带来了巨大挑战。为此，本文提出了一种基于双阶段注意力的多门专家混合编码器-解码器（MMoE-DAED）网络，用于在宽工作条件下对 PCC 过程进行动态建模。由长短时记忆（LSTM）网络组成的编码器-解码器用于从随时间变化的输入数据中提取特征，并学习由过程的惯性和延迟特性引起的复杂动态交互。编码器和解码器分别采用了双阶段注意机制，以选择最相关的输入特征及其在时间序列数据中的相关性。为了提高多输出预测的准确性，实施了考虑多任务学习相关性的多门专家混合物（MMoE）框架。利用 PCC 实验装置的运行数据得出的仿真结果表明，所提出的建模方法能在较宽的运行范围内准确预测二氧化碳捕获率和汽提塔底部温度的稳态值和动态趋势。二氧化碳捕集率的 RMSE、MAPE 和 R2 指数分别为 2.1592、0.0295 和 0.9641，汽提塔底部温度的 RMSE、MAPE 和 R2 指数分别为 0.1491、0.0003 和 0.9833。在 PCC 模拟器上的验证进一步验证了 MMoE-DAED 模型的准确性和效率，与模拟器相比，该模型的计算时间减少了 80.87%。本文为复杂能量转换过程的数据驱动动态建模指明了新方向。

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引用次数: 0

Experimental investigation on temperature distribution characteristics inside the condensing tube of the R134a two-phase natural circulation loop R134a 两相自然循环回路冷凝管内温度分布特性的实验研究

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-05 DOI: 10.1016/j.applthermaleng.2024.124816

Yunsheng Chen , Liping Huang , Zhenhui He , Shizhe Wen

Temperature distribution of two-phase flow inside the condensing tube can effectively reflect the heat transfer characteristic of the fluid, playing a pivotal role in the study of heat transfer in two-phase flow systems. In this study, we use the stainless steel capillary sealed distributed fiber Bragg grating (S-DFBGs) to measure and characterize the temperature distribution of R134a fluid inside the condensing tube under steady-state (pump-driven two-phase circulation) and unsteady-state (type I and II density wave instabilities in two-phase natural circulation loop) conditions, and the frequency and time domain characteristics of the fluid temperature distribution inside the tube has been investigated in detail. Through frequency-domain analysis, the temperature spectrum inside the condensing tube can indentify two types of the instability together with flowrate and pressure. Through time-domain analysis, temperature distribution inside the condenser can dermine the phase transition point, hence the condensation length. Moreover, two types of the instability exhibit different temperature fluctuation characteristics, providing reliable and effective information for further research on two phase natural circulation instability mechanisms.

冷凝管内两相流的温度分布能有效反映流体的传热特性，在研究两相流系统的传热过程中起着举足轻重的作用。本研究利用不锈钢毛细管密封分布式光纤布拉格光栅（S-DFBGs）测量和表征了稳态（泵驱动两相循环）和非稳态（两相自然循环回路中的I型和II型密度波不稳定性）条件下冷凝管内R134a流体的温度分布，详细研究了管内流体温度分布的频域和时域特征。通过频域分析，冷凝管内的温度谱与流速和压力一起确定了两种不稳定类型。通过时域分析，冷凝器内的温度分布可以确定相变点，从而确定冷凝长度。此外，两种不稳定类型表现出不同的温度波动特征，为进一步研究两相自然循环不稳定机制提供了可靠有效的信息。

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引用次数: 0

Experimental and numerical investigation on a hybrid high-temperature downhole thermal management system integrating liquid cooling and phase change material 集成液体冷却和相变材料的混合高温井下热管理系统的实验和数值研究

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-05 DOI: 10.1016/j.applthermaleng.2024.124804

Jiale Peng , Jiacheng Li , Siqi Zhang , Guanying Xing , Jinlong Ma , Bofeng Shang , Xiaobing Luo

The downhole electronics must operate in an extremely thermal environment for several hours. Previous researches have proved that passive thermal management systems (PTMSs) are able to protect downhole electronics over extended durations. However, conventional PTMSs commonly suffer from a significant thermal resistance between the electronics and phase change materials (PCM), which restricting the efficient heat transfer to the PCM and consequently reducing the effective operating time. In this study, a hybrid thermal management system (HTMS) integrating liquid cooling and phase change thermal energy storage technique was proposed to enhance the internal heat transfer performance of downhole electronics and extend the operation duration. An active heat transfer channel was established between the electronics and PCM through liquid cooling system, and thus the generated heat was efficiently transferred and stored in PCM. The thermal performance of the proposed HTMS was investigated both experimentally and numerically. The accuracy of the numerical model was validated through experimental results, with a deviation lower than 6 %. The experimental results show that the temperature difference between the heat source and the heat storage module (HSM) was reduced by up to 51.9 °C, and the workable time was increased by up to 166 mins compared to the system without liquid cooling. The proposed HTMS exhibits superior heat transfer performance, which contributes to achieving a longer effective operation duration and holds extensive and profound application prospects in the field of thermal management for downhole electronic devices.

井下电子设备必须在极热环境中工作数小时。以往的研究证明，被动热管理系统（PTMS）能够在较长时间内保护井下电子设备。然而，传统的 PTMS 通常在电子元件和相变材料（PCM）之间存在较大的热阻，从而限制了向 PCM 的有效热传导，进而缩短了有效工作时间。本研究提出了一种集成液体冷却和相变热能存储技术的混合热管理系统（HTMS），以提高井下电子设备的内部传热性能并延长运行时间。通过液体冷却系统，在电子元件和 PCM 之间建立了主动传热通道，从而将产生的热量有效地传递并储存在 PCM 中。我们通过实验和数值计算研究了拟议 HTMS 的热性能。实验结果验证了数值模型的准确性，偏差低于 6%。实验结果表明，与没有液体冷却的系统相比，热源与储热模块（HSM）之间的温差最多可减少 51.9 °C，可工作时间最多可延长 166 分钟。所提出的 HTMS 具有优异的传热性能，有助于实现更长的有效工作时间，在井下电子设备热管理领域具有广泛而深远的应用前景。

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引用次数: 0

Investigation of battery safety states based on thermal propagation and expansion analysis: Experimental studies on different packaging forms 基于热传播和热膨胀分析的电池安全状态调查：不同封装形式的实验研究

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-05 DOI: 10.1016/j.applthermaleng.2024.124800

Jinghan Zhang , Zhenpo Wang , Tengfeng Jiang , Peng Liu , Zhiwei Sun , Tongxin Shan , Bin Chen , Qing Wang , Jichao Hong

Lithium-ion batteries are highly susceptible to thermal runaway under harsh conditions, posing significant safety risks for electric vehicles. The differences in thermal runaway propagation across battery systems with varying manufacturing methods (including packaging and internal stacking) and the study of changes in expansion force within battery modules are crucial for improving safety and developing early warning systems for battery systems. This study investigates the thermal runaway and propagation behavior of lithium-ion batteries under various conditions, focusing on state of charge (SOC), internal manufacturing processes (electrode stacking and winding), and packaging types (pouch and prismatic) through a series of novel experiments. The results show that batteries at high SOC levels are at a greater risk of thermal runaway propagation, with winding pouch cells displaying more severe runaway behavior. In contrast, prismatic cells, despite experiencing intense explosions with an equivalent force of up to 42.3 g of TNT, exhibit relatively milder propagation. Furthermore, the study incorporates heat transfer analysis during thermal runaway propagation, identifying key phenomena such as the formation of negative pressure zones before explosions and changes in expansion forces at the module level. Based on these findings, a new safety evaluation method is proposed to assess the risk, hazards, and severity of thermal runaway, offering valuable insights for enhancing battery safety management and fire prevention strategies.

锂离子电池在恶劣条件下极易发生热失控，给电动汽车带来极大的安全风险。不同制造方法（包括包装和内部堆叠）的电池系统在热失控传播方面的差异，以及电池模块内部膨胀力变化的研究，对于提高电池系统的安全性和开发早期预警系统至关重要。本研究通过一系列新颖的实验，研究了锂离子电池在不同条件下的热失控和传播行为，重点关注充电状态（SOC）、内部制造工艺（电极堆叠和卷绕）以及包装类型（袋装和棱柱装）。结果表明，电池在高 SOC 水平下发生热失控的风险更大，卷绕袋电池的失控行为更为严重。相比之下，棱柱电池尽管经历了等效于 42.3 克 TNT 的剧烈爆炸，却表现出相对温和的传播。此外，研究还结合了热失控传播过程中的热传导分析，确定了一些关键现象，如爆炸前负压区的形成和模块级膨胀力的变化。基于这些发现，我们提出了一种新的安全评估方法，用于评估热失控的风险、危害和严重程度，为加强电池安全管理和火灾预防策略提供了有价值的见解。

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引用次数: 0

Experimental study on the low-temperature preheating performance of positive-temperature-coefficient heating film in the prismatic power battery module 棱柱形动力电池模块中正温度系数加热膜低温预热性能的实验研究

IF 6.1 2区工程技术 Q2 ENERGY & FUELS

Applied Thermal Engineering

Pub Date : 2024-11-05 DOI: 10.1016/j.applthermaleng.2024.124798

Jiangyun Zhang , Ruiqi Hu , Hongni Huang , Ruli Zhang , Guoqing Zhang , Dan Shao , Xiaoyong Wang , Yuliang Wen , Jin Luo

The performance of a power battery directly affects the thermal safety performance of the vehicle. Aiming at the improvement of thermal safety of lithium-ion batteries under low temperature condition, this study focuses on the effect of the positive-temperature-coefficient (PTC) heating film on the heating performance of batteries through experimental testing. First, the side and bottom of the cell were heated, and the heat transfer path and mode of the single cell were analyzed. The effects of different power densities and geometric positions on the heating effect were studied by testing the heating time and temperature consistency. Second, for the battery module, a low-temperature heating thermal management heat transfer model was built to analyze the heating mechanism of the heating film under different heating power densities. Finally, the results of these studies were synthesized to obtain the optimal heating power density. The results show that for the cell, the optimum power density of side heating and bottom heating is 0.5 W /cm² and 0.4 W /cm², respectively. The time required for side heating from −20 °C to 10 °C is 730 s lower than that of bottom heating, and the maximum temperature difference is 1.885 °C lower. For battery modules, a power density of 0.5 W/cm² was appropriate for both bottom and side heating methods. Due to the existence of heat conduction between battery packs, the battery modules will be quickly and evenly preheated. Under the optimal power density, the time length for side heating from –20 °C to 10 °C was 1459 s, and the maximum temperature difference was 6.32 °C; bottom heating time required slightly more time (1783 s), and the maximum temperature difference was 6.221 °C. Side heating can be beneficial for the rapid preheating of the battery module. This study will contribute to improving the performance and safety of batteries in cold environments.

动力电池的性能直接影响车辆的热安全性能。为了提高锂离子电池在低温条件下的热安全性能，本研究通过实验测试，重点研究了正温度系数（PTC）加热膜对电池加热性能的影响。首先，对电池的侧面和底部进行加热，分析单个电池的传热路径和模式。通过测试加热时间和温度的一致性，研究了不同功率密度和几何位置对加热效果的影响。其次，针对电池模块，建立了低温加热热管理传热模型，分析了不同加热功率密度下加热膜的加热机理。最后，综合这些研究结果，得出了最佳加热功率密度。结果表明，对于电池而言，侧面加热和底部加热的最佳功率密度分别为 0.5 W /cm2 和 0.4 W /cm2。侧面加热从 -20 °C 到 10 °C 所需的时间比底部加热短 730 秒，最大温差低 1.885 °C。对于电池模块，底部和侧面加热方法的功率密度均为 0.5 W/cm2。由于电池组之间存在热传导，电池模块会快速均匀地预热。在最佳功率密度下，侧面加热从-20 °C到10 °C的时间长度为1459 s，最大温差为6.32 °C；底部加热所需时间稍长（1783 s），最大温差为6.221 °C。侧面加热有利于电池模块的快速预热。这项研究将有助于提高电池在寒冷环境中的性能和安全性。

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引用次数: 0