Experimental study of the influencing factors and mechanisms of the pressure-reduction and augmented injection effect by nanoparticles in ultra-low permeability reservoirs

Nanoparticles(NPs)have gained significant attention as a functional material due to their ability to effectively enhance pressure reduction in injection processes in ultra-low permeability reservoirs.NPs are typically studied in controlled laboratory conditions,and their behavior in real-world,complex environments such as ultra-low permeability reservoirs,is not well understood due to the limited scope of their applications.This study investigates the efficacy and underlying mechanisms of NPs in decreasing injection pressure under various injection conditions(25—85℃,10—25 MPa).The results reveal that under optimal injection conditions,NPs effectively reduce injection pressure by a maximum of 22.77%in core experiment.The pressure reduction rate is found to be positively correlated with oil saturation and permeability,and negatively correlated with temperature and salinity.Furthermore,particle image velocimetry(PIV)experiments(25℃,atmospheric pressure)indicate that the pressure reduction is achieved by NPs through the reduction of wall shear resistance and wettability change.This work has important implications for the design of water injection strategies in ultra-low permeability reservoirs.

Optimization of Gas-Flooding Fracturing Development in Ultra-Low Permeability Reservoirs

Ultra-low permeability reservoirs are characterized by small pore throats and poor physical properties, which areat the root of well-known problems related to injection and production. In this study, a gas injection floodingapproach is analyzed in the framework of numerical simulations. In particular, the sequence and timing of fracturechanneling and the related impact on production are considered for horizontal wells with different fracturemorphologies. Useful data and information are provided about the regulation of gas channeling and possible strategiesto delay gas channeling and optimize the gas injection volume and fracture parameters. It is shown that inorder to mitigate gas channeling and ensure high production, fracture length on the sides can be controlled andlonger fractures can be created in the middle by which full gas flooding is obtained at the fracture location in themiddle of the horizontal well. A Differential Evolution (DE) algorithm is provided by which the gas injectionvolume and the fracture parameters of gas injection flooding can be optimized. It is shown that an improvedoil recovery factor as high as 6% can be obtained.

Numerical Simulation of Combustion in 660MWTangentially Fired Pulverized Coal Boiler on Ultra-Low Load Operation

In this paper,the combustion conditions in the boiler furnace of a 660 MWtangential fired pulverized coal boiler are numerically simulated at 15%and 20%rated loads,to study the flexibility of coal-fired power units on ultra-low load operation.The numerical results show that the boiler can operate safely at 15%and 20%ultra-low loads,and the combustion condition in the furnace is better at 20%load,and the tangent circles formed by each characteristic section in the furnace are better,and when the boiler load is decreased to 15%,the tangent circles in the furnace begin to deteriorate.The average flue gas temperature of different areas of the furnace shows that when the boiler furnace operates under ultra-low load conditions,the average smoke temperature of the cold ash hopper at 20%load is basically the same as the average smoke temperature at 15%load;in the burner area,the average smoke temperature of the cold ash hopper at 20%load is about 50 K higher than that at 15%load;in the burned out area,the average smoke temperature of the cold ash hopper at 20%load is slightly higher than that at 15%load.The average temperature of flue gas in the furnace showed a tendency to increase rapidly with the height of the furnace,then slow down and fluctuate the temperature in the burner area,and finally increase slightly in the burnout area due to the further combustion of combustible components to release heat,and then began to decrease.

Properties of Ultra-low Thermal Expansion LAS Transparent Glass-ceramics Prepared by Spodumene

The glass-ceramics were prepared with the spodumene mineral as the main raw material,and the effects of ZrO_(2)replacing TiO_(2)on the samples were systematically investigated.The results show that the substitution of ZrO_(2)for TiO_(2)is not conductive to precipitate𝛽β-quartz solid solution phase,but can improve the transparency and flexural strength of glass-ceramics.And the glass-ceramic with the highest visible light transmittance(87%)and flexural strength(231.80 MPa)exhibits an ultra-low thermal expansion of-0.028×10^(-7)K^(-1)in the region of 30-700℃.

THE OPERATION METHOD OF ULTRA-LOW-VOLUME SPRAYING WITH AIRPLANE

Techniques and measurements of ultra-low-volume spraving with airplane are studied. From practice it shows tha we can achieve good results of prevention and control of diseases and pests, if we take the following measures: The speed of flying is 160 km/h. The height of flying is 5 to 7m for plain and 15 to 20m for mountain area. The flashing point is over 70℃. The sparying width is 60m. The size of fog drop is 80 to 120μ. The density of fog drop is over 10 drops per cm2.

Assessment of Lubrication Property and Machining Performance of Nanofluid Composite Electrostatic Spraying(NCES)Using Different Types of Vegetable Oils as Base Fluids of External Fluid

The current study of minimum quantity lubrication(MQL)concentrates on its performance improvement.By contrast with nanofluid MQL and electrostatic atomization(EA),the proposed nanofluid composite electrostatic spraying(NCES)can enhance the performance of MQL more comprehensively.However,it is largely influenced by the base fluid of external fluid.In this paper,the lubrication property and machining performance of NCES with different types of vegetable oils(castor,palm,soybean,rapeseed,and LB2000 oil)as the base fluids of external fluid were compared and evaluated by friction and milling tests under different flow ratios of external and internal fluids.The spraying current and electrowetting angle were tested to analyze the influence of vegetable oil type as the base fluid of external fluid on NCES performances.The friction test results show that relative to NCES with other vegetable oils as the base fluids of external fluid,NCES with LB2000 as the base fluid of external fluid reduced the friction coefficient and wear loss by 9.4%-27.7%and 7.6%-26.5%,respectively.The milling test results display that the milling force and milling temperature for NCES with LB2000 as the base fluid of external fluid were 1.4%-13.2%and 3.6%-11.2%lower than those for NCES with other vegetable oils as the base fluids of external fluid,respectively.When LB2000/multi-walled carbon nanotube(MWCNT)water-based nanofluid was used as the external/internal fluid and the flow ratio of external and internal fluids was 2:1,NCES showed the best milling performance.This study provides theoretical and technical support for the selection of the base fluid of NCES external fluid.

Effect of Ultra-low Temperature on Carbonation Performance of SFRRC and Prediction Model

Through the rapid carbonation test of SFRRC with different fiber volume fractions at ultralow temperature,the influence of ultra-low temperature damage on the carbonation resistance of SFRRC was analyzed,which provides a theoretical basis for the application of SFRRC in ultra-low temperature engineering.The experimental results show that ultra-low temperatures can significantly weaken the carbonization resistance of SFRRC.When the temperature reaches 160℃,the carbonization depth increases by 67.66%compared with the normal state.The proper amount of steel fiber has an evident influence on the carbonation resistance of the material.However,when the addition amount exceeds the optimum content,the carbonation resistance of the material decreases.The grey prediction model established by constructing the original sequence can reasonably predict the carbonation resistance of SFRRC after ultra-low temperatures.

Active straining engineering on self-assembled stacked Ni-based hybrid electrode for ultra-low overpotential

Generating sufficient strains on metal surfaces are highly challenging owing to that most metals can deform plastically to relax the strains on the surfaces.In this work,we developed a facile but highly efficient stacked deposition strategy to in situ activation and reconstruction of NiO/NiOOH on Ni matrix,following with the migration of Fe ions to NiOOH.The Fe sites on the Ni/NiO/NiOOH facilitate the formation of the stable*OH oxygenated intermediates,and the Ni matrix in the catalyst provides the catalyst excellent stability.The oxygen evolution reaction(OER)performance of the stacked NiFe-5 with compressive strain displays the strengthened binding to oxygenated intermediates and superior OER activity,the ultralow overpotentials of 162 versus reversible hydrogen electrode at 10 mA cm^(-2).On the other hand,the Ni-5 without the incorporation of Fe has shown an outstanding hydrogen evolution reaction(HER)activity,affording an overpotential of 47 mV at 10 mA cm^(-2).The NiFe-5‖Ni-5 enables the overall water splitting at a voltage of 1.508 V to achieve 20 mA cm^(-2) with remarkable durability.The stacked deposition strategy improves binding strength of Ni-based catalysts to oxygenated intermediates via generating compressive strain,causing high catalytic activities on OER and HER.

Effect of steam spraying on a sintering bed on sinter quality and the emission of flue gas pollutants

The technology for spraying a sintering bed and thus improving sinter quality indicators while reducing the emission of flue gas pollutants has recently become an important research topic.The impacts on sinter quality and emissions when spraying the sintering surface with different amounts and flow rates of steam were investigated in this study.The sinter quality indicators were most effectively improved by spraying 180 g of steam flow continuously at a rate of 0.02 m^(3)/min for 15 min after ignition for 8 min.The optimal effect on emission reduction was obtained by spraying 90 g of steam flow continuously at a rate of 0.01 m^(3)/min for 15 min after ignition for 8 min.

激光复合冷喷涂技术研究进展

冷喷涂是一种基于材料高速撞击产生剧烈塑性变形实现结合的沉积方法,具备加工温度低、沉积效率高、热影响小等优势,已在增材制造、工业关键零部件的修复再制造等领域展现出巨大潜力。冷喷涂复合制造技术是一种新兴技术,其中激光复合冷喷涂是一个重要的方向,近年来得到了越来越多的关注。对激光复合冷喷涂技术研究进展进行回顾和总结,对激光预处理、激光同步复合和激光后处理3种复合方式进行重点阐释。针对每种复合方式,分别从复合原理、复合优势及复合效果3个方面进行总结,对比激光复合冷喷涂技术与单一技术在沉积层微观组织以及性能等方面的差异。通过对激光复合冷喷涂技术最新进展的全面总结和归纳,将为进一步推动激光复合冷喷涂技术的研究和应用提供指导和参考。

基于轻量化PointNet网络的林果园喷雾作业靶标实时识别方法

为了进一步提高喷雾机器人靶标检测的精准性、实时性和应用部署的实用性,该研究提出一种基于轻量化PointNet网络的林果园喷雾作业靶标实时识别方法。首先通过区域提取降采样、地面分割和改进DBSCAN聚类等点云预处理方法提取原始点云中的靶标;然后通过移动最小二乘上采样将靶标点云转化为满足点云识别网络输入要求的点云数据;最终通过在PointNet网络中引入残差模块和改进循环剪枝算法轻量化PointNet网络,完成林果树靶标的实时识别。试验结果表明,在ModelNet40数据集上,轻量化PointNet网络可达89.7%的准确率;在实际苗圃环境的试验中,该研究方法对靶标的识别准确率可达92.49%,同时误识率与拒识率分别为13.4%和6.47%,相较PointNet网络识别准确率提升了4.38个百分点,误识率和拒识率分别降低了7.2和4.07个百分点;轻量化PointNet网络识别准确率仅比PointNet++网络低1.14个百分点,误识率和拒识率分别高了0.9和1.12个百分点。但是轻量化PointNet网络的模型参数量较PointNet网络和PointNet++网络的模型参数量显著减少,仅为PointNet网络的11.5%,PointNet++网络的27.02%;运算量相较PointNet网络、PointNet++网络分别减少13.3和76.79个百分点。该研究提出的轻量化PointNet网络具有较高的实时性、精确性和鲁棒性,能够满足林果园喷雾作业的靶标识别需求,可为林果园喷雾作业靶标实时识别提供参考。

钢纤维喷射砂浆力学性能与流动度多因素正交试验分析

为探究基体因素对钢纤维喷射砂浆力学性能和流动度的影响,基于正交试验方法对砂浆试件进行了力学性能和流动度测试。结果表明:砂胶比(A)对劈裂抗拉强度的影响较大,对7 d抗压强度有一定的影响,对后期抗折强度影响特别显著;钢纤维掺量(B)对劈裂抗拉强度、前期抗折强度和前中期抗压强度的影响分别为特别显著、显著和不显著;速凝剂掺量(C)对7 d前抗压强度、中后期劈裂抗拉强度影响显著;粉煤灰掺量(D)仅对后期抗压强度的影响显著;前述四种因素掺量对流动度的影响均不显著。由层次分析法得到对抗压强度、抗折强度、劈裂抗拉强度和流动度改善效果最佳的配合比分别为A1B3C3D1、A3B3C1D2、A3B3C3D1、A2B1C1D3,由功效系数法得到综合最佳配合比为A2B3C1D2。钢纤维在基体中起桥接与锚固加强的作用,速凝剂在水化过程中消耗大量的Ca(OH)_(2)并生成钙矾石,促使喷射砂浆早期强度迅速提升。

微米级类球形介孔材料用于乙烯聚合催化剂

采用2-(4-氯磺酰苯基)乙基三甲氧基硅烷对类球形介孔材料进行疏水处理,制备了疏水性类球形介孔材料,将其作为载体,通过气流式喷雾干燥技术制备了聚乙烯催化剂。对疏水处理前后的类球形介孔材料进行了XRD、N2吸附-脱附、TEM、SEM表征,考察了气流式喷雾干燥过程中载气流量和浆料浓度对聚乙烯催化剂的影响,并评价了催化剂的乙烯聚合性能。实验结果表明,类球形介孔材料在疏水处理后孔结构和微观结构稳定;最佳喷雾干燥条件为喷雾干燥器进、出风口温度分别为140,105℃,载气流量为30 L/s,浆料浓度为30%(w);在最佳喷雾干燥条件下制备的催化剂用于乙烯聚合时,催化活性为28000 g/g,远高于工业用TS-610硅胶制备的催化剂的活性(9000 g/g),反应得到的聚合物性能也优于TS-610硅胶制备的催化剂得到的聚乙烯粉料。

余热回收喷淋塔喷淋优化研究

针对喷淋塔内烟气偏流影响烟气与下落液滴群热质交换的问题,构建并通过试验验证了喷淋塔内气液流动及余热回收理论模型,基于液滴自调整效应,运用CFD技术模拟研究4种喷淋层布置方式下余热回收喷淋塔的性能,获得了最佳喷淋方案及其喷淋参数。结果表明:与常规单层均匀喷淋方式相比,增设半层喷淋能够有效提升塔内烟气流动均匀性,塔内烟气均匀度由1降至0.3左右,喷淋塔全热交换效率最多可提升20%;半层喷淋最佳布置位置在烟气入口中心线上3 m处;综合考虑余热回收效果和运行成本,最佳喷淋液滴直径为0.6~0.8 mm,最佳水气比为5 kg/kg。构建的喷淋塔内烟气余热回收模型与提出的喷淋优化方法可为其特性分析、工艺优化、参数设计及运行提供理论指导。

连栋温室分段变距喷雾机器人设计与试验

针对国内连栋温室缺乏植保喷雾机、机械走直定位与换轨转向精度低等问题,设计了一种连栋温室分段变距喷雾机器人,在实现无人化喷药的同时提高作业精度。为满足连栋温室机械作业路轨结合、精准切换的要求,提出一种通用型移动底盘,并确定其关键设计参数;为减少底盘上下轨时的偏移量,设计轨上矫正装置,通过分析计算及试验验证,确定其安装余量为4 mm;针对底盘对轨误差大的问题,提出一种二维码融合陀螺仪及光电传感器双向垂直寻迹的路面关键点定位与转向控制方法。设计分段变距喷雾装置,提出一种丝杆滑台驱动的喷杆变距方案,分析校验其驱动参数以满足工作要求;基于滚针轴承设计喷杆辅助防抖装置,减小因喷杆剧烈抖动带来的滑台与喷杆损伤。开发底盘运动及分段变距喷雾控制系统,实现喷雾机器人在连栋温室内的全程自动化作业。最后,对样机进行底盘性能与喷雾效果试验。底盘作业时直线行走与对轨误差平均值分别为4.8、5.8 mm,满足控制精度要求;避障距离为34 cm,满足安全性要求;防抖装置的安装使喷杆行进方向的抖动量从-1°~1.3°降低到±0.4°内,喷头方向的抖动量从±0.5°降低到±0.3°内,防抖效果显著;分段变距喷雾作业后,盛果期番茄叶片正面雾滴沉积量为1.76μL/cm^(2),反面沉积量为0.2μL/cm^(2),雾滴体积中径在100~180μm之间,满足作业要求。

红肉火龙果粉的发泡微波冷冻干燥制备与质量评价

制备浆果粉末产品是延长其货架期的有效手段。为降低干燥过程能耗和保留产品营养成分,该研究以平均含水率(87.03±1.26)%的新鲜红肉火龙果果浆为原料,采用冷冻干燥和喷雾干燥两种方法制备了火龙果粉末。以残余湿含量、色泽和典型生物活性成分甜菜红素、芦丁和总酚保留率为指标对产品质量进行了评价。用质量比为3%(w/w)的分离乳清蛋白和2.5%(w/w)的果胶为添加剂制备了未发泡和发泡2种样品,进行了传统和微波冷冻干燥试验。结果表明,使用石英底盘,在30˚C、20 Pa下,发泡样品比未发泡样品冷冻干燥时间缩短了39.06%;施加1 W微波功率时,未发泡和发泡样品微波冷冻干燥时间比无微波时分别缩短了18.75%和12.82%。用碳化硅底盘替代石英底盘,在30˚C、20 Pa和1 W下,发泡样品微波冷冻干燥时间比未发泡和发泡样品传统无微波冷冻干燥分别缩短了65.62%和43.59%。分别以5.5%(w/w)的分离乳清蛋白和15.6%(w/w)的麦芽糊精为添加剂,进行了喷雾干燥试验。工艺参数为进风温度150˚C、出风温度85˚C、进料速度28 mL/min。冷冻干燥产品的甜菜红素、芦丁和总酚保留率分别在72%、84%和75%以上,而喷雾干燥产品的保留率显著降低。该研究采用的冷冻干燥方法能够大幅缩短干燥时间、提高产品质量,为浆果类粉末产品的制备提供工业解决方案。

镁合金表面热喷涂WC-10Co-4Cr粒子沉积及分布特性

为了探究高速空气燃料热喷涂(activated combustion-high velocity air fuel,AC-HVAF)过程中喷涂粒子撞击基材后的沉积特性。采用AC-HVAF热喷涂技术在AZ80镁合金基体上沉积WC-10Co-4Cr硬质涂层。通过离散沉积实验获得薄层沉积粒子,探讨各种沉积形貌的种类、形成原因、结合机制及射流中粒子的径向和轴向分布。结果表明:在AC-HVAF粒子沉积过程中,嵌入型沉积为主要的沉积形貌,同时包含少量的破碎型与空腔型沉积粒子。在涂层的形成过程中,嵌入型沉积对涂层/基体结合性能起重要作用;空腔型沉积的小颗粒及破碎型沉积的大颗粒是造成沉积效率下降的主要原因。喷涂粒子主要集中在射流中心,越靠近射流边缘,空腔型沉积粒子越多,最终导致AC-HVAF粒子射流呈现出空间分布特征。

加热温度对工业规模CeCl_(3)喷雾焙烧反应器影响的数值模拟

CeO_(2)颗粒由于具有优异的性能,市场对CeO_(2)颗粒的需求逐年增加。为探究使用在氧化铁颗粒工业化生产的Ruthner型喷淋焙烧反应器生产CeO_(2)颗粒的可能性,结合单液滴失重试验,使用ANSYS Fluent软件,分别探究550、650、750和850℃四种不同加热温度对反应器的影响。单液滴失重试验表明,氯化铈和氯化铁、氯化亚铁的热解过程基本一致,使用该型反应器制备CeO_(2)颗粒理论上可行。对小型工业反应器进行等比例建模,研究反应器内部化学反应的具体过程。结果表明,550℃是最合适的温度,对工业生产具有一定指导意义。

单旋翼无人机植保作业系统的研制与实验研究

为了提高植保无人机的工作效率,降低无人机的操作难度,研制了单旋翼无人机植保作业系统。根据植保作业流程,单旋翼无人机植保作业系统实现启动、预热、起飞、飞行、喷洒作业、加药和返航等全过程无人工干预的自动飞行作业。单旋翼无人机植保控制系统包括作业平台、飞行控制、数据链路、地面站系统、系统应用、飞行器管理、用户信息管理、专业知识管理、大数据业务,实现了喷洒区域的精准控制,地面站系统与飞行系统的控制与交互,植保信息的存贮与分析等。通过实验研究表明:单旋翼无人机植保作业系统有效提高了植保工作效率,降低了飞行操作人员的操作难度。

喷淋作用下的深水测试放喷热辐射规律及关键参数

在深水天然气测试过程中,多相混合物会通过地面流程分离、泄压、加热后通过燃烧臂放喷燃烧,现场一般采用喷淋的方式来降低热辐射的影响。为了降低深水放喷测试作业时平台及燃烧臂的热辐射风险隐患,首先采用Thornton模型研究了火焰表面辐射能量、视角系数以及水幕透射率等参数,构建了喷淋作用下放喷火焰的热辐射通量计算模型,并结合现场燃烧放喷下的仿真模型,应用有限元软件分析了放喷喷淋影响下的火焰温度和辐射量变化规律。研究结果表明:(1)喷淋形成的水幕使靠近平台区域的温度和辐射量明显降低,放喷管道附近的辐射量由2 050 W/m^(2)减小到了1 840 W/m^(2);(2)在单个水幕的作用下,水幕吸收了一定的热辐射量,水幕温度从11.85℃上升到约26.85℃;(3)由于平台附近的空气中CO_(2)和H_(2)O含量较低,空气的热辐射吸收系数较小,温度主要受到热对流的影响,空气温度基本保持在26.85~36.15℃之间;(4)不同放喷管径和产量变化下平台附近区域的温度和辐射量变化趋势基本一致,管径减小使得辐射峰值增大。结论认为,该研究成果进一步明确了深水测试放喷不同工况下的热辐射分布,为深水地面放喷热辐射设计分析及安全控制提供了技术支撑。