Investigation of gravity influence on EOR and CO_(2) geological storage based on pore-scale simulation

Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.

Interannual variability of mixed layer depth and heat storage of upper layer in the tropical Pacific Ocean

By using the upper layer data(downloaded from the web of the Scripps Institution of Oceanography),the interannual variability of the heat storage of upper layer(from surface to 400 m depth) and the mixed layer depth in the tropical Pacific Ocean are investigated. The abnormal signal of the warm event comes from the central and west Pacific Ocean, whereas it is regarded that the abnormal signal of the warm event comes from the east Pacific Ocean in the popular viewpoint. From the viewpoint on the evolution of the interannual variability of the mixed layer depth and the heat storage of the whole upper layer, the difference between the two types of El Nino is so small that it can be neglected. During these two El Nino/La Nina events(1972/1973 and 1997/1998), other than the case of the heat storage or for the mixed layer depth, the abnormal signal propagates from the central and west Pacific Ocean to the east usually by the path along the equator whereas the abnormal signal propagates from the east to the west by the path northern to the equator. For the interannual variability, the evolution of the mixed layer depth corresponds to that of the heat storage in the upper layer very well. This is quite different from the evolution of seasonality.

Numerical Simulation and Analysis of Migration Law of Gas Mixture Using Carbon Dioxide as Cushion Gas in Underground Gas Storage Reservoir

One of the major technical challenges in using carbon dioxide( CO2) as part of the cushion gas of the underground gas storage reservoir( UGSR) is the mixture of CO2and natural gas. To decrease the mixing extent and manage the migration of the mixed zone,an understanding of the mechanism of CO2and natural gas mixing and the diffusion of the mixed gas in aquifer is necessary. In this paper,a numerical model based on the three dimensional gas-water two-phase flow theory and gas diffusion theory is developed to understand this mechanism. This model is validated by the actual operational data in Dazhangtuo UGSR in Tianjin City,China.Using the validated model,the mixed characteristic of CO2and natural gas and the migration mechanism of the mixed zone in an underground porous reservoir is further studied. Particularly,the impacts of the following factors on the migration mechanism are studied: the ratio of CO2injection,the reservoir porosity and the initial operating pressure. Based on the results,the optimal CO2injection ratio and an optimal control strategy to manage the migration of the mixed zone are obtained. These results provide technical guides for using CO2as cushion gas for UGSR in real projects.

A rationale for the development of thermally stable nanostructured CeO_2-ZrO_2-containing mixed oxides

CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for practical application since temperatures up to 1273 K are easily experienced by these materials under real working conditions. In the present paper, we investigated how hydrothermal treatments applied to cakes of doped and undoped ZrO2-rich CeO2-ZrO2 precursors might improve the thermal stability of the final CeO2-ZrO2 solid solution. A rationale was developed that allowed to correlate the morphology of the hydrothermaUy treated cake with the thermal stability at 1273 K of the final product, which did not depend on the composition of the mixed oxides.

汽车工厂Painted Body Storage的仿真研究

文章是针对于汽车厂PaintedBodyStorage(PBS)的模拟仿真研究。汽车厂装配车间是典型的混流生产方式的车间。在喷漆车间,为了减少颜色频繁变换带来的喷头清洗费用,需要尽量将相同颜色的车辆进行组合。PBS是位于油漆车间和装配车车间之间调配空间,控制投入到装配线的车辆顺序,装配线中要尽量要分散相同配置的车辆。满足车辆的接近禁止和均匀化等约束,一旦不能满足,就需要补助人员的投入。PBS的目标是尽量满足这两种约束条件。文章介绍了汽车工厂的PBS研究。提出了装配线的车辆顺序进场、出场的优化算法,通过模拟仿真证明了该算法的优越性,进行了运营因素中的灵敏度分析。

Mixed polyanion cathode materials:Toward stable and high-energy sodium-ion batteries

Sodium-ion batteries(SIBs)are considered as one of the most fascinating alternatives to lithium-ion batteries for grid-scale energy storage applications because of the low cost and wide abundance of sodium resources.Among various cathode materials,mixed polyanion compounds come into the spotlight as promising electrode materials due to their superior electrochemical properties,such as high working voltage,long cycling stability,and facile reaction kinetics.In this review,we summarize the recent development in the exploration of different mixed polyanion cathode materials for SIBs.We provide a comprehensive understanding of the structure-composition-performance relationship of mixed polyanion cathode materials together with the discussion of their sodium storage mechanisms.It is anticipated that further innovative works on the material design of advanced cathode materials for batteries can be inspired.

OPTICAL STORAGE MECHANISM AND HIGH-ORDER DIFFRACTION PROPERTIES OF NITROAZOBENZENE-CONTAINING POLYESTER FILMS

Using Nd:YAG second harmonic pulse (100 ps), the optical storage properties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] and poly [2'-chloro-4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] have been studied by multiwave mixing. The high-order diffractions of the orientation gratings induced by anisotropy via the reorientation of nitroazobenzene groups and optical information storage with long-term stability have been realized by multiwave mixing in their films. Up to 3rd order forward diffraction was detected in two wave mixing, while up to 4th order backward diffraction was observed in degenerated four wave mixing. The recording mechanism was explained by the trans-cis-trans isomerization cycles of azobenzene groups. The isomerization of these azobenzene groups probably undergoes with inversion mechanism under the experimental conditions. The information recorded in these films has been kept for more than 6 months.

Study on Catalysts with Rhodium Loading on Different Cerium-Zirconium Mixed Oxides

The catalysts with Rh loading on different cerium-zirconium mixed oxides were characterized by BET, H2-TPR and OSC. The effects of different cerium-zirconium mixed oxides on catalytic performance and thermal stability of Rh loaded catalyst were studied. The results show that: (1) Rh can enhance cerium-zirconium mixed oxides OSC and catalytic reaction rates; (2) cerium-zirconium mixed oxides with high Ce contents and low Zr contents are more favorable to the stability of catalysts. Moreover, the contents of CeO2 have important effect on catalysts characteristics, and the addition of some rare earth components, such as La, Pr and Nd also have some influences.

Cost Optimal Selection of Storage Tanks in LPG Vaporization Station

Liquefied petroleum gas (LPG) is an important urban gas source in China. Before supplied to customers by pipeline supply systems, LPG is stored in tanks in LPG vaporization stations. Designers usually decide the number and the size of storage tanks by their experience during constructions of vaporization stations. These decisions are usually not best and most economical. To solve the problem, a compact mixed integer nonlinear programming model has been developed in this paper. The objective is to minimize annual storage cost of the vaporization station. The model has been transformed into a general nonlinear programming model by transforming integer variables and 0-1 variables into continuous variables. One LPG vaporization station was taken as an example to illustrate the usage of the model. The results show that the optimal storage scheme can be determined accurately and quickly by the model and about 15% of storage cost can be saved every year after optimization.

Thermal performance and evaluation of a novel stratified and mixed flexible transformation solar heat storage unit

It is necessary to satisfy the flexible requirements of solar heat storage systems to provide efficient heating and constant-temperature domestic hot water at different periods.A novel heat storage tank with both stratified and mixing functions is proposed,which can realize the integration of stable stratification and rapid mixing modes.In this research,a three-dimensional heat transfer model of the heat storage tank with stratified and mixed dual modes was established,and a thermal performance test system for the tank was built in the State Key Laboratory of Green Building in Western China.Moreover,a new evaluation index representing the mixing speed is proposed.The stratification effect and mixing characteristics of the tank were studied under different comprehensive conditions.The results show that the exergy efficiency of the tank with a stratified pipe can be increased by 10%–15%compared to that of a conventional tank.Additionally,the recommended optimal flow rate range for well-stratified tanks is 4–6 L/min.The mixing nozzle of the tank reduces the mixing reaction coefficient by 0.27 and significantly reduces the mixing time.This study provides critical guidance to meet the flexible thermal needs of users and implement high-performance applications using the stratified and mixing modes of heat storage tanks.

辣木与高丹草混合青贮效果的研究

辣木(Moringa oleifera)富含蛋白质、维生素、矿物元素和不饱和脂肪酸,高丹草(Sorghum bicolor×S.sudanese)含糖量高且生物产量大,两者均为营养丰富饲料资源。本研究将辣木叶(Y)、辣木枝(Z)与辣木枝叶(ZY)分别以6个比例(0、20%、40%、60%、80%、100%)与高丹草(G)混贮,青贮40 d后检测青贮饲草的感官品质(气味、色泽、质地)、发酵品质(有机酸含量)和营养成分[粗蛋白(CP)、粗纤维(CF)、粗脂肪(EE)、无氮浸出物(NFE)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、粗灰分(Ash)、碳水化合物(WSC)],探究不同辣木组织(Y、Z、ZY)和高丹草适宜的混合青贮比例。结果显示,高丹草单贮感官评定总分最高,辣木叶与高丹草混贮平均分次之,辣木枝叶混贮感官评分等级最低;80%辣木叶与20%高丹草混贮显著降低了CF和NDF含量,40%辣木枝与60%高丹草混贮显著降低了CF含量并提高了NFE含量,60%辣木枝叶与40%高丹草混贮显著降低了CF含量并提高了EE含量。综上所述,辣木叶、枝、枝叶与高丹草最佳混贮比例分别为80%、40%和60%,辣木叶与高丹草以80%和20%混贮时效果最佳,本研究为有效利用辣木与高丹草资源从而促进云南生态畜牧业的可持续发展提供了依据。

考虑时变线阻的多储能SOC稳定均衡控制策略

在直流微电网中,由于线路阻抗大小差异的复杂化,难以保证各储能单元之间达到荷电状态(state-of-charge,SOC)均衡。为此,提出一种考虑时变线阻的SOC均衡改进控制策略。首先,通过线路阻抗和SOC幂指数构造的平衡因子来修正控制系数,提高SOC的辨识度。同时,利用输出电流来约束平衡因子,提高系统的抗扰能力。在SOC均衡之后,SOC平衡因子G变为1,此时依赖线路阻抗信息但不受线路阻抗变化影响,可平稳地保持电流分配。并且结合输出电流构造的电压补偿环节有效地解决了母线电压质量和SOC均衡控制效果之间的矛盾。其次,针对基于SOC均衡的改进控制策略易受恒功率负载影响的问题,利用混合势函数理论进行建模,得到稳定性判据,有利于保障系统的稳定运行。最后,仿真结果表明,所提出的改进下垂控制能够有效地消除线路阻抗的影响,提高电流分配精度,实现SOC均衡,并验证了在各种突发扰动及极端情况下所提控制策略的有效性和正确性。

用户侧重力-蓄电池混合储能系统配置优化与效益分析

现有的用户侧储能以蓄电池储能为主,手段较为单一,回收不当对环境也会造成危害;同时用电高峰期峰谷差较大,这既提升了用户用电成本,也给电网的稳定运行带来了挑战。针对此问题,建立了重力储能的充放电模型,并在此基础上提出一种应用蓄电池与重力储能相结合的混合储能模型。首先以功率、容量和寿命等变量为条件对该模型进行了适当的约束。下一步以用户综合收益最高为目标函数利用量子粒子群优化算法对模型进行配置寻优。然后得出了混合储能最优的功率、容量配置。在MATLAB 2021b软件环境下,使用江苏省南京市用户侧智能电能表实际负荷数据算例进行分析,最后可以得出混合储能系统及其优化方案可以减小用户侧用电峰谷差,并且使用户侧用电成本有所降低的结论,验证了其合理性与经济性。

内相粒径对现场混装乳化基质老化过程的影响

为研究内相粒径对现场混装乳化基质老化过程的影响,利用可程式高低温箱对乳化基质进行周期性储存来加速基质老化,使用激光粒度仪、光学显微镜、水溶法和数字黏度计测试乳化基质老化过程中的内相粒径、微观结构、硝酸铵析晶量及黏度的变化。测试结果表明:内相粒径为9.47μm的现场混装乳化基质在储存1个周期后就已严重析晶,在储存3个周期后硝酸铵析晶量为储存前的3.32倍,黏度增大45.72%。内相粒径为3.76μm的现场混装乳化炸药在储存2个周期后平均内相粒径增大为10.06μm,硝酸铵析晶量为储存前的1.43倍,黏度增大10.18%,储存3个周期后的硝酸铵析晶量为储存前的1.71倍,黏度增大14.48%,内相粒径越小,现场混装乳化基质的储存稳定性越好。在实际生产中,应根据混装车设备性能的实际情况,考虑基质泵送及其安全性,尽可能制备内相粒径约小于5μm、黏度合理的乳化基质,用以生产现场混装乳化炸药。

基于混合储能荷电状态的光伏直流微网系统能量分配策略

针对混合储能系统在平抑光伏波动以及负荷投切时荷电状态(SOC)易越限问题,提出一种基于混合储能SOC的多模式协调控制策略。在传统低通滤波功率分配的基础上,提出一种基于超级电容荷电状态的动态功率修正策略,使超级电容出力后SOC向安全状态恢复;同时,为避免蓄电池频繁切换充放电状态,在其响应环节加入优化后的延时控制。此外,根据光伏出力情况、混合储能SOC,设计出满足直流微网系统动态平衡的六种运行模式,实时调节各储能单元出力情况。在MATLAB/Simulink中搭建了光伏直流微网混合储能系统仿真模型,仿真结果表明所提策略在各工况下均能稳定运行,有效延长了储能介质使用寿命。

新工科建设背景下线上线下混合式教学提升产出导向课程目标达成度的优势及教学设计案例——以“果蔬贮藏加工学”为例

新工科建设背景下的高等工科教育对专业课的高阶性、创新性和挑战度提出了新的要求,传统课堂教学遭遇瓶颈。线上线下混合式教学基于课程目标开展反向教学设计,将线上自主学习和线下课堂教学进行有机的深度融合,聚焦高阶能力的培养,是提高专业课程教学质量和课程目标达成度的有效途径。以“果蔬贮藏加工学”为例阐述了开展混合式教学改革的必要性,并展示了混合式教学设计的案例。

抽水蓄能电站单机容量与机组转速选择

通过分析国内外已建抽水蓄能电站机组主要技术参数,研究抽蓄电站定转速混流式水泵水轮机水头与单机容量、参数水平的关系,提出了不同水头段抽水蓄能电站单机容量和比速系数选择原则,推荐了合适的机组额定转速范围,可提高抽水蓄能电站水泵水轮机选型设计的工作效率和成果质量。

压缩空气储能地下储气库热力学改进模型研究

【目的】明晰地下储气库的热力学过程是压缩空气储能(compressed air energy storage,CAES)电站安全设计与运行调度的重要基础。【方法】现有地下储气库热力学模型在计算热量交换时,存在高压储气阶段热损失偏大和低压储气库阶段补热过多的不足。本文在全面分析地下储气库热力学模型理论基础合理性的前提下,先分析储气库热量计算偏差的形成根源;再提出改进模型。【结果】研究结果表明:现有的热力学计算解析模型忽略了CAES地下储气库在运行过程中温度分布的不均匀性,这种温度分布的不均匀导致储气室洞壁与压缩空气之间的对流换热模型失真,导致温度计算结果偏差大。考虑混合对流换热的改进模型二可以较好地解决储气阶段温度计算结果与真实结果之间偏差过大的问题。算例分析证明了改进模型二的合理性。【结论】本文的改进模型二可为CAES地下储气库容积优化设计与效率分析提供计算依据。

含混合式抽水蓄能电站的水光蓄日内互补运行研究

在传统水电机组基础上加入可逆式机组构成混合式抽水蓄能电站增加水电调节能力,可与光伏电站联合运行,平抑新能源发电的不稳定性。为研究不同季节典型日下,含混合式抽水蓄能电站的水光蓄互补运行方式,构建以发电量最大和出力波动最小为目标的水光蓄互补运行短期调度模型,提出双层嵌套模型求解思路,考虑光伏出力的波动性,求解不同运行工况下含混合式抽水蓄能电站的水光蓄互补运行短期调度模型。计算结果表明,在不同来水及不同光伏出力过程的前提下,混合式抽水蓄能电站可采取不同运行工况以满足目标函数,不仅可以促进光伏并网消纳,还可增加水电发电量,减少弃水,为大量光伏资源并网下混合式抽水蓄能电站运行方式提供参考。

芝麻花生混合压榨调和油储藏稳定性的研究

旨在为提高油脂储藏稳定性提供参考,以花生油为原料,通过Schaal烘箱法,在考察芝麻素对花生油储藏稳定性影响的基础上,考察调和油2种制备方式(植物油直接混合、原料混合再压榨)对芝麻花生调和油储藏稳定性的影响。结果表明:添加芝麻素可降低花生油储藏期间的酸值、过氧化值、茴香胺值、共轭二烯值、共轭三烯值、巴比妥酸值,延长氧化诱导时间;将芝麻与花生混合后再压榨制备的调和油的储藏稳定性优于芝麻油与花生油直接混合制备的调和油的。综上,芝麻油可提高花生油的储藏稳定性,且混合压榨法可作为制备调和油的一种更好选择。