3D printing of poly(ethyleneimine)-functionalized Mg-Al mixed metal oxide monoliths for direct air capture of CO_(2)

Direct air capture(DAC)of CO_(2)plays an indispensable role in achieving carbon-neutral goals as one of the key negative emission technologies.Since large air flows are required to capture the ultradilute CO_(2)from the air,lab-synthesized adsorbents in powder form may cause unacceptable gas pressure drops and poor heat and mass transfer efficiencies.A structured adsorbent is essential for the implementation of gas-solid contactors for cost-and energy-efficient DAC systems.In this study,efficient adsorbent poly(ethyleneimine)(PEI)-functionalized Mg-Al-CO_(3)layered double hydroxide(LDH)-derived mixed metal oxides(MMOs)are three-dimensional(3D)printed into monoliths for the first time with more than 90%adsorbent loadings.The printing process has been optimized by initially printing the LDH powder into monoliths followed by calcination into MMO monoliths.This structure exhibits a 32.7%higher specific surface area and a 46.1%higher pore volume,as compared to the direct printing of the MMO powder into a monolith.After impregnation of PEI,the monolith demonstrates a large adsorption capacity(1.82 mmol/g)and fast kinetics(0.7 mmol/g/h)using a CO_(2)feed gas at 400 ppm at 25℃,one of the highest values among the shaped DAC adsorbents.Smearing of the amino-polymers during the post-printing process affects the diffusion of CO_(2),resulting in slower adsorption kinetics of pre-impregnation monoliths compared to post-impregnation monoliths.The optimal PEI/MeOH ratio for the post-impregnation solution prevents pores clogging that would affect both adsorption capacity and kinetics.

Defect-rich Mg-Al MMOs supported TEPA with enhanced charge transfer for highly efficient and stable direct air capture

Due to the advantages of low energy consumption and high CO_(2) selectivity, the development of solid amine-based materials has been regarded as a hot research topic in the field of DAC for the past decades.The adsorption capacity and stability over multiple cycles have been the top priorities for evaluation of practical application value. Herein, we synthesized a novel DAC material by loading TEPA onto defect-rich Mg_(0.55)Al-O MMOs with enhanced charge transfer effect. The optimal Mg_(0.55)Al-O-TEPA67% demonstrates the highest CO_(2)uptake of(3.0 mmol g^(-1)) and excellent regenerability, maintaining ~90% of the initial adsorption amount after 80 adsorption/desorption cycles. The in situ DRIFTS experiments suggested the formation of bicarbonate species under wet conditions. DFT calculations indicated that the stronger bonding between Mg_(0.55)Al-O support and solid amine was caused by the abundance of oxygen defects on MMOs confirmed by XPS and ESR, which favors the charge transfer between the support and amine,resulting in intense interaction and excellent regenerability. This work for the first time conducted comprehensive and systematic investigation on the stabilization mechanism for MMOs supported solid amine adsorbents with highest uptake and superior cyclic stability in depth, which is different from the most popular SiO_(2)-support, thus providing facile strategy and comprehensive theoretical mechanism support for future research about DAC materials.

Operating limits and features of direct air capture on K_(2)CO_(3)/ZrO_(2) composite sorbent

Potassium carbonate-based sorbents are prospective materials for direct air capture(DAC).In the present study,we examined and revealed the influence of the temperature swing adsorption(TSA)cycle conditions on the CO_(2) sorption properties of a novel aerogel-based K_(2)CO_(3)/ZrO_(2) sorbent in a DAC process.It was shown that the humidity and temperature drastically affect the sorption dynamic and sorption capacity of the sorbent.When a temperature at the sorption stage was 29℃ and a water vapor pressure P_(H2O) in the feed air was 5.2 mbar(1 bar=105 Pa),the composite material demonstrated a stable CO_(2) sorption capacity of 3.4%(mass).An increase in sorption temperature leads to a continuous decrease in the CO_(2) absorption capacity reaching a value of 0.7%(mass)at T=80℃.The material showed the retention of a stable CO_(2) sorption capacity for many cycles at each temperature in the range.Increasing PH2O in the inlet air from 5.2 to 6.8 mbar leads to instability of CO_(2) sorption capacity which decreases in the course of 3 consecutive TSA cycles from 1.7%to 0.8%(mass)at T=29℃.A further increase in air humidity only facilitates the deterioration of the CO_(2) sorption capacity of the material.A possible explanation for this phenomenon could be the filling of the porous system of the sorbent with solid reaction products and an aqueous solution of potassium salts,which leads to a significant slowdown in the CO_(2) diffusion in the composite sorbent grain.To investigate the regeneration step of the TSA cycle in situ,the macro ATRFTIR(attenuated total reflection Fourier-transform infrared)spectroscopic imaging was applied for the first time.It was shown that the migration of carbonate-containing species over the surface of sorbent occurs during the thermal regeneration stage of the TSA cycle.The movement of the active component in the porous matrix of the sorbent can affect the sorption characteristics of the composite material.The revealed features make it possible to formulate the requirements and limitations that need to be taken into account for the practical implementation of the DAC process using the K_(2)CO_(3)/ZrO_(2) composite sorbent.

Distributed Air &Missile Defense with Spatial Grasp Technology

A high-level technology is revealed that can effectively convert any distributed system into a globally programmable machine capable of operating without central resources and self-recovering from indiscriminate damages. Integral mission scenarios in Distributed Scenario Language (DSL) can be injected from any point, runtime covering & grasping the whole system or its parts, setting operational infrastructures, and orienting local and global behavior in the way needed. Many operational scenarios can be simultaneously injected into this spatial machine from different points, cooperating or competing over the shared distributed knowledge as overlapping fields of solutions. Distributed DSL interpreter organization and benefits of using this technology for integrated air and missile defense are discussed along with programming examples in this and other fields.

室内空气调节系统的研究与设计

车间环境中,生产活动可导致空气质量恶化,极大影响员工身体健康。文章提出了一种空气调节系统,用于监测室内空气粉尘和VOC污染物浓度,适时开启换气系统,使空气参数保持在较高的水平。该系统集成多组粉尘和VOC检测模块和双向换气装置,根据发生空气质量恶化区域自适应调整空气流动路径,有针对性的净化空气。车间外设置风向传感器,根据自然风的风向调整室内换气方向,提高换气效率。各个监测点和执行点利用WiFi实现自组网,点与点之间密切配合,提高系统换气效率。验证试验表明:监测器能够稳定运行,点与点之间配合良好,高效率、针对性实现空气净化,大大改善了车间生产环境。

美国定向能机动近程防空计划进展分析

美国定向能机动近程防空(directed energy maneuver-short range air defense,DE M-SHORAD)计划通过击伤、摧毁或压制旋转翼无人机、固定翼无人机以及火箭弹、火炮炮弹、迫击炮弹(rockets,artillery and mortar,RAM)等威胁目标,为机动部队提供伴随防空,对抗新兴威胁,属于美国陆军防空反导现代化的优先项目之一。首先介绍了DE M-SHORAD研制计划;其次详细分析了系统结构,并由系统参数评估了系统的作战性能;最后梳理了系统的研制进展。通过综合分析可知,DE M-SHORAD系统采用最佳组件,通过快速原型方法实现激光武器系统在装甲车上的集成;为降低技术风险,该计划在发展方式上分为两个阶段,首先集成、测试2 kW~5 kW机动实验型高能激光器(mobile experimental high-energy laser,MEHEL),然后再研制50 kW级的多任务高能激光器(multi-mission high-energy laser,MMHEL)。经计算可得:MEHEL和MMHEL对无人机的最大射程分别约为0.77 km、4.8 km。

电站直接空冷系统运行状态数字化实时显示技术

随着人工智能、数字孪生技术及数字化虚拟技术的快速发展,采用数字化虚拟技术实现电站直接空冷机组空冷岛运行状态的实时监测成为可能。首先,建立空冷岛三维模型,通过数值计算获得空冷岛空气状态参数,开发空冷岛运行状态数据库及显示和查询软件;其次,基于数字孪生技术,在电厂设置气象站,获得环境气温、风速、风向实时变化数据,连同机组运行工况参数输入监测软件;最终,计算获得空冷岛空气运行状态并进行三维显示。基于数字孪生技术的空冷系统空气运行状态实时显示技术避免了现场大量装设测点的投资和检修维护工作,为智慧电站的发展奠定了基础。

空冷岛喷嘴预冷模拟研究

直接空冷岛的换热效果受气温影响严重,为提高夏季高温工况下空冷岛的冷却效果,常采用喷水减温技术。以西北地区某空冷机组为例,采用数值模拟计算分析了喷嘴喷水角度、喷水量和喷水压力对冷却效果的影响。为更好地分析喷嘴喷出的液滴在空间上的发展并量化冷却效果,采用了新的冷却效率。研究结果表明:在本文研究参数内,随着流动距离的增加,冷却效率逐渐提高。喷水量对冷却效率影响最大,喷水量分别为0.48kg/s和1.58kg/s时的冷却效率分别为24.472%和48.071%,冷却效率几乎翻倍,而喷嘴喷水压力的影响稍弱,喷嘴喷水角度影响最小。在调整喷嘴参数时可以着重考虑喷嘴喷水量和喷水压力。

考虑天气影响的火电机组空冷系统性能预测方法

【目的】直接空冷机组是一部分缺水地区常用的火力发电形式,由于其采用空气作为冷却介质,因此运行受到诸多限制。为解决直接空冷机组受环境影响大和耗煤量高的问题,对空冷岛换热性能进行预测研究。【方法】基于河北省某超临界2×600 MW机组的历史运行数据,利用MATLAB软件计算历史空冷岛性能,将历史数据作为训练集和测试集,通过长短期记忆(long short-term memory,LSTM)神经网络机器学习算法,实现对未来一段时间内的空冷岛性能预测。在不改变模型参数的条件下,通过去除各项特征的方式确定特征重要性排名,基于此确定最佳特征选择策略,进一步优化模型。考虑到空冷岛性能受天气影响大,为提升模型在特殊天气下的预测能力,将原数据集结合历史天气预报数据,编写考虑天气因素的预测程序,以预测空冷岛未来一段时间性能,并对预测结果进行可视化分析。【结果】所采用的预测模型预测准确度明显高于传统自回归移动平均模型(autoregressive integrated moving average model,ARIMA),对未来1 h以内的直接空冷机组换热性能预测拟合优度均在0.90以上。【结论】模型所采用的数据特征及算法可以为直接空冷机组的稳定运行提供数据支撑,为智慧电厂的建设提供技术基础。

导流板对某660 MW电厂空冷单元运行性能的影响及优化研究

以660 MW直接空冷机组空冷系统为研究对象,采用Fluent软件建立空冷单元模型,研究轴流风机对空冷单元管束换热性能的影响。针对空气旋流和横向风引起的空冷单元凝结管束换热不均匀问题,提出加装导流板的优化措施,研究无风工况和横向风工况下空冷单元管束凝结量分布情况,对比优化前后管束换热的均匀性。结果显示:加装导流板具有较好的导流作用,无风工况下,加装全部导流板可使得单侧管束均分因子减少40.00%,加装迎风侧部分导流板可使得管束总凝结量增大0.76%,同时单侧管束均分因子减少22.00%;横向风会降低管束换热性能,使左、右侧管束换热不均匀,左侧进风时,加装全部导流板可使得左侧管束均分因子最大减少38.93%,右侧管束均分因子最大减少38.24%。

Model predictive control of indoor thermal environment conditioned by a direct expansion air conditioning system

Temperature and humidity are two important factors that influence both indoor thermal comfort and air quality.Through varying compressor and supply fan speeds of a direct expansion(DX)air conditioning(A/C)unit,the air temperature and humidity in the conditioned space can be regulated simultaneously.However,most existing controllers are designed to minimize the tracking errors between the system outputs with their corresponding settings as quickly as possible.The energy consumption,which is directly influenced by the compressor and supply fan speeds,is not considered in the relevant controller formulations,and thus the system may not operate with the highest possible energy efficiency.To effectively control temperature and humidity while minimizing the system energy consumption,a model predictive control(MPC)strategy was developed for a DX A/C system,and the development results are presented in this paper.A physically-based dynamic model for the DX A/C system with both sensible and latent heat transfers being considered was established and validated by experiments.To facilitate the design of MPC,the physical model was further linearized.The MPC scheme was then developed by formulating the objective function which sought to minimize the tracking errors of temperature and moisture content while saving energy consumption.Based on the results of command following and disturbance rejection tests,the proposed MPC scheme was capable of controlling temperature and humidity with adequate control accuracy and sensitivity.In comparison to linear-quadratic-Gaussian(LQG)controller,better control accuracy and lower energy consumption could be realized when using the proposed MPC strategy to simultaneously control temperature and humidity.

Thermodynamic analysis on direct air capture for building air condition system:Balance between adsorbent and refrigerant

Direct air capture(DAC)is one of the most potential technologies to mitigate CO_(2) emission.Adsorption technol-ogy is recognized as a promising CO_(2) capture method in view of its desirable characteristics including reusability of adsorbents and low capital investment.To further improve thermal performance,evaporation/condensation heat of vapor compression refrigeration(VCR)cycle in air condition system of buildings is adopted for adsorp-tion/desorption process of DAC.Thermal performance of a 4-step temperature swing adsorption process(TSA)is analyzed at various adsorption/desorption temperatures by using different adsorbents.Analysis on Coefficient of Performance(COP)of VCR cycle is also conducted in search for a balance between adsorbent and refrigerant.Taking both real working capacity and COP into consideration,Mg-MOF-74&R134a is the best choice for more amounts of CO_(2).Real working capacity of Mg-MOF-74 is up to 0.38 mol•kg−1 at 70°C,which is twice as much as that of zeolite 13X.While zeolite 13X&R134a shows the best performance of two cycles in view of exergy efficiency and COP,which could reach 81.9%and 7.21,respectively,at 35°C.These matches will provide some guidelines for the practical application of the combination of DAC with heating,ventilation and air conditioning(HVAC).

光热电站主机直接空冷系统优化探讨

光热发电是一种比较有发展前景的可再生能源发电形式,具有良好的储能和调峰能力。受制于水资源条件,目前我国光热电站的主机冷却系统多采用直接空冷系统。直接空冷系统配置对机组经济性和盈利能力均会产生较大影响。在总结和分析光热电站投资构成及运行特点的前提下,依托某案例工程进行直接空冷系统优化计算和分析。对光热电站直接空冷系统气象数据选取与处理、以及电价敏感性分析进行初步探讨。由于上网电价及成本电价普遍较高,与常规火电厂直接空冷系统相比较,光热电站直接空冷系统配置倾向于初始温差(ITD)值较低、风速较小、空冷凝汽器面积较大的方案。

地铁站高效直膨式空调机组运行特性及控制策略研究

介绍了地铁高效直膨空调制冷机组的特点与运行控制方式,结合深圳地铁某站点的实机应用与同站线内采用相似规格的螺杆机组站点进行对比,对空调机组的运行电费、设备能效、系统能效等方面进行分析。结果表明,高效直膨空调机组运行费用低、节能减排效果明显。铁某站点的实机应用与同站线内采用相似规格的螺杆机组站点进行对比,对空调机组的运行电费、设备能效、系统能效等方面进行分析。结果表明,高效直膨空调机组运行费用低、节能减排效果明显。

医院专项区域暖通空调系统设计要点探讨

介绍了专项区域各科室HVAC系统设计要点,主要是冷热源及加湿器的形式的选择原则,对于不同区域需要注意的事项,像DSA区域送风天花的设计、设备间温度处理;中心供应室设备夹层温度过高、环氧乙烷气体排放的处理;B2生物安全柜的补风问题;静脉配置中心的抗生素配置中心及抗肿瘤配置中心排风问题;病理科室内空气处理、排风处理;手术部的特殊手术室设计要点;监护病房及产科空气处理机组的选择等问题,以具体工程项目为例,给出了具体的解决方案。

基于一次风压双向智控的锅炉经济运行关键技术的研究

锅炉发电厂磨煤机采用正压直吹式制粉系统,普通存在一次风量测量数据不准确的问题,导致磨煤机一次风量自动控制系统不能正常投入。针对神华九江公司1000 MW机组的一次风控制实际需求,研究基于一次风压双向智控的锅炉经济运行关键技术,适用于机组深度调峰及全负荷工况一次风优化的智能控制系统,在确保机组AGC及各磨煤机一次风量、风速及出口温度的前提下,提高各磨煤机热风门开度,减少一次风压力损失,有效降低了一次风机功耗和机组供电煤耗。

基于空间谱估计技术测向系统的开场测试

本文利用相关干涉仪体制无线电监测测向系统的测试验证技术基础,通过分析基于空间谱估计技术的无线电测向系统的开场测试参数及方法,设计了针对空间谱测向系统特性的开场测试场地,完善了监测设施测试验证的技术手段。

直接热泵的出风温度裂隙和优化研究

采用直接热泵技术可以提升电动汽车的电能利用效能和综合热管理水平。但在春秋季等需要采暖、除湿的工况下,由于直接热泵的蒸发器和内置冷凝器的热量耦合在理论上可能会出现出风温度不连续的问题,即“出风温度裂隙”。文章研究了一种典型的直接热泵系统,在焓差实验室测试了10~30℃春秋季工况下出风温度的上下边界,确认了出风温度裂隙的存在。通过分析环境温度、压缩机性能、前端进风风量、空调箱进风温度等因素,提出了一系列优化对策,并进行了有效性验证,为解决直接热泵的出风温度裂隙提供了可能的解决方案。

直接空冷凝汽器干式吹扫系统喷嘴结构特性

运用CFD技术计算分析了不同喷嘴结构参数下喷嘴的内部流场,得到了喷嘴内部流场特性、出口参数等与喷嘴结构参数的关系。结果表明,喷嘴的收缩角对喷嘴内部流场和出口参数影响较小,最佳吹扫收缩角为40°;圆柱长度越短喷嘴内部流场变化越剧烈、喷嘴出口流量和压力越高,在满足吹扫强度要求下,为了提高吹扫的稳定性,圆柱长度的选取范围为25~40 mm;圆柱直径增大,吹扫能力越强,但是直径过大变截面处湍流越剧烈,吹扫稳定下降,因此在满足吹扫强度要求下,圆柱直径的选取范围为1.8~2.0 mm。