计及弃风的“电气互补-冷热联供”模式研究

针对弃风严重以及传统供暖方式存在难以“热电解耦”的问题,提出一种将蓄热式电锅炉、燃气锅炉、吸收式制冷机相结合的“电气互补-冷热联供”弃风消纳模式。首先,根据弃风和冷热负荷特性建立“电气互补-冷热联供”模型;然后,考虑供暖与制冷成本,构建“电气互补-冷热联供”经济性模型;最后,通过算例分析与传统“燃气锅炉-空调”供暖制冷模型的经济性进行对比。结果表明：所提模式可在消纳弃风的同时减少碳排放量,达到提升系统收益的目的。     

气泡粘度对水平槽道气泡减阻率影响的数值研究

采用多相流混合模型和雷诺应力湍流模型,对水平槽道气泡减阻进行了数值模拟;同时考虑了液相湍流诱导气泡聚合、气泡尾流诱导气泡聚合、湍流涡与气泡碰撞产生破碎作用对气泡减阻的影响。在保证雷诺数以及气相体积分数不变的情况下,调查了气相粘度变化以及气泡聚合、破碎物理因素对气泡减阻率和液相湍流的影响。研究表明:减阻率和液相湍流变化与气相粘度的大小具有直接关系;气泡减阻和液相湍流抑制是因气相粘度小于液相粘度而引起的,如气相的粘度大于液相的粘度时,液相湍流则被强化、气泡减阻现象消失;当气泡体积分数较低时,气泡聚合和破碎物理现象对液相湍流和减阻率的影响很小。     

流动风阻网格模型与热仿真设计方法优化动力电池模组结构的研究

风冷系统因结构简单、成本低等特点,在热管理系统中占据重要地位。目前常规的风冷热管理设计方法存在重复性工作多、设计时间长的缺点。本文提出空气流动风阻网格模型结合热力学模型仿真的设计方法,先采用空气流动风阻网格模型获得优化的电池结构,再采用热力学模型进行仿真求解,获得优化的电池模组的流场和温度场分布特性。仿真结果验证了优化结构的准确性。优化结果表明,“C”字形结构更有利于提升模组内单体电池冷却效果的一致性,并且优化后的“C”字形结构进一步提升了电池模组内单体电池温度场的一致性。此外,计算结果发现模组内空气流动方向为上进下出时可进一步降低模组内单体电池的最高温度,提升单体电池温度场的一致性。     

含电池储能系统的电热联合系统风电接纳能力评估

为促进风电消纳,减少“弃风”,将电池储能系统（BESS）接入电热联合系统。为考虑风功率的不确定性,基于风功率预测误差的概率特性建立风功率场景概率模型。然后,建立包含BESS的电热联合系统风电接纳能力评估模型。模型具有系统运行成本最低和“弃风”电量最小2个不同维度优化目标,且目标优化之间可能存在冲突。为求解该模型,基于改进主要目标法将其转换为多个单目标优化问题,并采用GAMS中DICOPT求解器给出风电接纳能力评估模型的帕累托解集。基于帕累托解集,从接纳电量和接纳成本两方面对BESS接入后的电热联合系统风电接纳能力进行深入分析。最后进行仿真分析,验证了该文所提模型及求解算法的有效性。     

气液两相流泵内气泡大小及分布规律研究

为了研究气液两相流离心泵内的气泡分布规律以及气泡大小对数值模拟的影响,采用高速摄像技术对泵内气液两相流动进行可视化试验,采用Fluent中的Eulerian模型和SST k-ω湍流模型对泵内的气液两相流动进行数值模拟.在转速为400 r/min、液相流量为10 m3/h和气相流量为0.5 L/min时,泵内流型为孤立泡...     

气泡尺寸对气缸盖沸腾换热的影响

在应用欧拉多相流模型仿真计算气液两相流沸腾换热时,离散相的气泡尺寸常常被看作常数,而实际上往往气泡具有不同的形状和尺寸,因此研究气泡尺寸大小对仿真计算结果的影响显得至关重要.以ANSYS Workbench为仿真计算平台,在计算流体动力学模块CFX中,用气液两相流沸腾换热计算模型,对不同气泡尺寸下柴油机气缸盖与冷却水腔所组成的流固耦合传热系统进行了整场离散、整场求解,得到了冷却水腔中气液两相流流场分布特性和气缸盖温度场分布,通过与试验结果的对比分析证明了计算模型的有效性.结果表明,在气泡尺寸大小为1,mm的情况下,仿真结果更接近试验结果,并且考虑气液两相流沸腾换热能够有效地降低气缸盖火力面排气道鼻梁区的最高温度,以此降低此处的热负荷.     

高压鼓泡反应器中NOx吸收过程及建模

基于鼓泡反应器对NO_x吸收中气相NO、NO_2和HNO_2,液相NO_x进行量化,实现NO_x质量守恒的测量,误差在±8%以内.建立三区反应模型,以气相出口NO和NO_2测量值与模拟值的相对误差为目标函数,获得了最优NO_2和NO传质系数、NO氧化动力学常数、液膜体积和表面积等参数.液膜区中HNO3浓度是鼓泡区的193～357倍;NO_2和NO吸收分别受气相扩散和液相控制;NO氧化反应受压力影响大,主要是链式反应控制;反应器中液膜产生的本质猜测是气泡夹带的液滴吸附于内表面.     

面向“双碳”目标的脆弱区域生态光伏模式研究

光伏作为大力发展的零碳能源之一,是“双碳”目标达成的主力军,有必要对生态光伏模式进行研究。在总结分析光伏阵列对气象、土壤和植被的影响,光伏电站区域的固碳增汇效益和生态系统服务价值估算研究现状的基础上,从成本约束下的生态-经济效益最大化和固碳效益最优化角度,提出了生态光伏的概念和内涵;基于脆弱区域特征,融合生态系统过程模型和InVEST效益核算模型,构建基于“双碳”目标的脆弱区域生态光伏模式。研究结果可为光伏发电与脆弱区域生态修复双重效益核算,开发路径识别,行业标准出台提供参考。     

水─汽浸没凝结射流两相流动的数值研究

本文对水－汽浸没凝结射流两相流动采用单流体模型及ｋ－ε－ｇ湍流模型进行了数值研究。得到了速度、温度、密度和气相体积分数等物理量的分布以及穿透区（含气区）的形状。穿透区的长度与相关的由实验得到的经验公式符合得很好。计算结果表明水的汽－液浸没凝结射流经历了气相流动、气液两相流动和液相流动等不同流动型态的变化，具有复杂的流场结构。     

全球加氢站产业、技术及标准进展综述

以美国、欧洲、日本、中国的加氢站作为考察对象,就产业投资运营、主要设备商、相关标准进行梳理,结果表明：在加氢站投资及运营管理方面,美国、欧洲、日本具有较为成熟的经验;在氢增压、储存、加注等技术方面,德国、日本保持领先地位。在诸多氢气和液氢的技术领域,美国保持领先地位;在一些细分技术领域,英国、法国、挪威、俄罗斯具有优势;在加氢站标准方面,美国、日本具有较为完善的标准体系。中国已解决70 MPa氢气增压、加注、储存等领域的部分技术难题,但与其他国家相比,离子液式氢压缩机、液氢泵、液氢储罐、液氢加氢枪等产品的研发仍需持续推进。     

车载高压氢气分级充注系统的设计与模拟

研究单级氢气充注时,氢气充注速率、初始温度和压力对氢气终了温度的影响。通过调用NIST REFPROP 中标准氢状态方程,模拟氢气在充注过程温度、压力、充注率等参数的变化。设计和模拟两级和三级氢气充注系统。结果表明：多级充注时,存在最佳的中间压力,使得充灌终了氢气温度最低,且增加级数可降低终了氢气温度。最后,对多级充注系统的能耗进行分析,结果表明随着级数的增加,系统的总能耗降低。     

CFD simulation of heat transfer and phase change characteristics of the cryogenic liquid hydrogen tank under microgravity conditions

The heat transfer and phase change processes of cryogenic liquid hydrogen (LH₂) in the tank have an important influence on the working performance of the liquid hydrogen-liquid oxygen storage and supply system of rockets and spacecrafts. In this study, we use the RANS method coupled with Lee model and VOF (volume of fraction) method to solve Navier-stokes equations. The Lee model is adopted to describe the phase change process of liquid hydrogen, and the VOF method is utilized to calculate free surface by solving the advection equation of volume fraction. The model is used to simulate the heat transfer and phase change processes of the cryogenic liquid hydrogen in the storage tank with the different gravitational accelerations, initial temperature, and liquid fill ratios of liquid hydrogen. Numerical results indicate greater gravitational acceleration enhances buoyancy and convection, enhancing convective heat transfer and evaporation processes in the tank. When the acceleration of gravity increases from 10^?2 g0 to 10^?5 g0, gaseous hydrogen mass increases from 0.0157 kg to 0.0244 kg at 200s. With the increase of initial liquid hydrogen temperature, the heat required to raise the liquid hydrogen to saturation temperature decreases and causes more liquid hydrogen to evaporate and cools the gas hydrogen temperature. More cryogenic liquid hydrogen (i.e., larger the fill ratio) makes the average fluid temperature in the tank lower. A 12.5% reduction in the fill ratio resulted in a decrease in fluid temperature from 20.35 K to 20.15 K (a reduction of about 0.1%, at 200s).     

Fluid thermal stratification in a non-isothermal liquid hydrogen tank under sloshing excitation

To the safe space operation of cryogenic storage tank, it is significant to study fluid thermal stratification under external heat leaks. In the present paper, a numerical model is established to investigate the thermal performance in a cryogenic liquid hydrogen tank under sloshing excitation. The interface phase change and the external convection heat transfer are considered. To realize fluid sloshing, the dynamic mesh coupled the volume of fluid (VOF) method is used to predict the interface fluctuations. A sinusoidal excitation is implemented via customized user-defined function (UDF) and applied on tank wall. The grid sensitivity study and the experimental validation of the numerical mode are made. It turns out that the present numerical model can be used to simulate the unsteady process in a non-isothermal sloshing tank. Variations of tank pressure, liquid and vapor mass, fluid temperature and thermal stratification are numerically investigated respectively. The results show that the sinusoidal excitation has caused large influence on thermal performance in liquid hydrogen tank. Some valuable conclusions are arrived, which is important to the depth understanding of the non-isothermal performance in a sloshing liquid hydrogen tank and may supply some technique reference for the methods of sloshing suppression.     

填充开孔泡沫铝的固液相变蓄冷器设计与实验研究

为进一步满足固液相变蓄冷器需求,在计算固液相变蓄冷器漏热的基础上进行了相应优化,使用开孔泡沫铝作为固液相变蓄冷器填充材料,搭建实验台进行不同负载功率下的液氮固体蓄冷系统性能实验研究。实验结果表明：所设计的固体蓄冷系统能够在0.5 W的热负载下工作4.23 h; 2 W热负载实验条件下,固体蓄冷系统能够在温度小于65 K条件下工作1 h。     

A computational fluid dynamic study of the filling of a gaseous hydrogen tank under two contrasted scenarios

The filling of a horizontal hydrogen tank designed for light duty vehicles is investigated by means of multi-physics numerical simulations. The simulation approach, implemented in OpenFOAM, includes compressible Reynolds-Averaged Navier-Stokes (RANS) modeling of the fluid flow and heat transfer in the solid parts. The simulations are carried out for 2D-axisymmetric and 3D configurations. Two filling scenarios of the tank, leading to two distinct thermal behaviors, i.e. homogeneous versus heterogeneous, are simulated and compared to the experimental data issued from the HyTransfer project. In the homogeneous case, where no thermal stratification occurs, the 2D and 3D simulation results are close to the experimental ones. A phenomenon of jet flapping is identified via the 3D simulation. In the heterogeneous case, where thermal stratification occurs, the 3D simulation captures an averaged temperature close to the experimental one, as well as the instant at which the thermal gradients appear. It also captures the deflection of the jet, which is a central element in the emergence of the thermal gradients.     

The design and optimization of a cryogenic compressed hydrogen refueling process

Cryo-compressed hydrogen storage has excellent volume and mass hydrogen storage density, which is the most likely way to meet the storage requirements proposed by United States Department of Energy（DOE）. This paper contributes to propose and analyze a new cryogenic compressed hydrogen refueling station. The new type of low temperature and high-pressure hydrogenation station system can effectively reduce the problems such as too high liquefaction work when using liquid hydrogen as the gas source, the need to heat and regenerate to release hydrogen, and the damage of thermal stress on the storage tank during the filling process, so as to reduce the release of hydrogen and ensure the non-destructive filling of hydrogen. This paper focuses on the study of precooling process in filling. By establishing a heat transfer model, the dynamic trend of tank temperature with time in the precooling process of low-temperature and high-pressure hydrogen storage tank under constant pressure is studied. Two analysis methods are used to provide theoretical basis for the selection of inlet diameter of hydrogen storage tank. Through comparative analysis of the advantages and disadvantages of the two analysis methods, it is concluded that the analysis method of constant mass flow is more suitable for the selection in practical applications. According to it, the recommended diameter of the storage tank at the initial temperature of 300 K, 200 K and 100 K is selected, which are all 15 mm. It is further proved that the calculation method can meet the different storage tank states of hydrogen fuel cell vehicles when selecting the pipe diameter.     

燃料电池车车载储氢系统的技术发展与应用现状

综述了燃料电池车车载储氢系统技术，包括高压氢、液氢、金属氢化物、低温吸附、纳米碳管高压吸附以及液体有机氢化物等的研究进展及其车载应用现状。参照燃料电池车对车载储氢系统单位重量储氢密度与体积储氢密度的目标要求，对目前已应用和处于研发阶段的一些储氢技术的性能指标和存在问题进行了分析讨论。同时对目前该领域的若干新的研究报道，如超高压轻质复合容器、混合储氢容器、b.c．c．储氢合金、超级活性碳和“浆液”双相储氢等，也作了简要介绍。     

Numerical study on thermodynamic growth of single hydrogen bubble in an infinite space

In the liquid hydrogen storage and delivery, cavitation and boiling bubbles are prone to occur, which reduces the safety and economy of the liquid hydrogen delivery. For the bubble in liquid hydrogen, its growth process is different from that of room temperature media owing to the thermodynamic properties. In this paper, a single bubble growth model in liquid hydrogen is developed considering temperature distribution inside the bubble. The growth of single bubble in liquid hydrogen is described and predicted by solving Rayleigh-Plesset equation, thermal diffusion equation, thermal equilibrium equation, and heat conduction equation in semi-infinite space simultaneously. The growth trend of bubble radius, radius growth rate, vapor pressure, thermal boundary layer thickness and temperature difference between boundary and center are investigated by the model. The influence of superheat and ambient pressure on the growth of single bubble in liquid hydrogen is investigated by analysis of variance (ANOVA) and range analysis method. The mechanism of the single bubble transform from dynamic growth to thermal growth is clarified by comparing the critical time of the above physical indicators.     

加氢站高压储氢瓶分级方法

应用真实气体状态方程,拟合了常用温度压力范围内的氢气压缩因子,建立了加氢站高压氢气多级加注的计算方法。以取气率作为指标,研究比较了二级加注和三级加注方式,讨论了等质量加注和变质量加注两种模式及储气压力和储气容积对取气率的影响。通过计算,发现三级变质量加注是最佳模式,可获得较高的取气率。研究表明:三级加注加氢站储氢瓶组的通用最佳容积比是4:3:2和2:2:1,研究结果对加氢站的设计和操作具有重要参考价值。     

Advanced turbulence modeling improves thermal gradient prediction during compressed hydrogen tank filling

In order to use gaseous hydrogen for mobility of light and heavy duty vehicles, the standard J2601 from the Society of Automotive Engineers (SAE) recommends that the temperature in the tank must not exceed 85 °C for safety reasons. Prior experiments reported that a vertical thermal stratification can occur during the filling of horizontal tanks under specific conditions. Thermodynamic modeling of hydrogen tank filling can predict the average gas temperature but not the onset of stratification. In a previous study, the computational fluid dynamics (CFD) software OpenFOAM was used to carry out simulations of hydrogen filling for a type IV 37 L tank. The CFD results, by comparison with experimental results, were capable to predict the rise of the thermal stratification with however an underestimation of thermal gradient magnitudes. The maximal temperature predicted at the end of the filling was 15.05 °C bellow the experimental measurements. In this work, the k − ω SST turbulence model is replaced by the k − ω SST SAS turbulence model to limit the prediction of high levels of eddy-viscosity in stagnation areas which over-diffuses the temperature. By using the same mesh as in the above mentioned study, (651 482 cells in the fluid region and 449 126 cells in solid regions), the k − ω SST SAS turbulence model is found to be more appropriate for CFD simulation of tank filling as it predicts a thermal gradient magnitude in the gas in better agreement with experimental measurements than the k − ω SST turbulence model for a similar time of simulation. The maximal temperature predicted at the end of the filling is 2.17 °C bellow the experimental measurements.