Efficient thermal management of superheated surfaces via fine water mist impingement is critical across numerous industrial applications, yet quantifying and optimizing the intricate heat-mass coupling remains a significant challenge. Here, we reveal and quantify a nonlinear cooling enhancement/suppression mechanism driven by the transient coupling of droplet kinetic energy, Leidenfrost vapor film evolution, and interfacial heat transfer. Through the numerical simulations incorporating an interface-confined phase change model, we rigorously elucidate the genesis of the M-shaped heat flux distribution. We mechanistically attribute this M-shape to non-uniform central vapor accumulation and pressure-gradient-driven radial transport, demonstrating its non-uniform suppression on local heat transfer. Crucially, we identify and quantitatively define "critical impact conditions"-encompassing critical droplet size and critical impact velocity-that effectively circumvent the profound inhibition of the Leidenfrost effect to maximize cooling efficiency. For instance, increasing impact velocity from 0.50 to 1.00 m/s leads to a remarkable 110.2% surge in total heat transfer, marking a fundamental transition from a low-efficiency (14.9% increase for 0.25-0.50 m/s) to high-efficiency cooling regime. The identification of this abrupt, stepwise enhancement, rather than a gradual trend, confirms the existence of a critical velocity threshold-the finding that fundamentally extends beyond parametric sensitivity analyses prevalent in the literature. This study provides unprecedented mechanistic insights into droplet-wall heat transfer and offers a novel parameter-based cooling strategy for precise enhancement and optimization of high-temperature cooling processes.

The adoption of environmental protection and energy conservation measures has led to increased interest among researchers and scholars in the centrifugal granulation of metallurgical slag and waste heat recovery technology. Variations in the production processes of metallurgical slag result in significant disparities in the physical properties of slag from different sources. Blast furnace slag and copper slag are two types of metallurgical slags distinguished by their characteristic properties. Blast furnace slag exhibits higher viscosity and surface tension, whereas copper slag displays lower viscosity and surface tension, resulting in differing granulation characteristics. This study employs numerical simulations to examine the flow patterns during centrifugal granulation and elucidate the mechanism of centrifugal granulation. The study determined that the breaking length to tip diameter ratio was consistent with the findings of Weber's research. Additionally, it observed the atypical granulation evolution of two types of slag at elevated flow rates, and examined the variation rules of breakup wavelength, tip diameter, crushing length, particle size distribution, and average particle size across varying flow rates. The study also noted that the centrifugal granulation effect of copper slag was significantly influenced by its surface tension. The aforementioned findings can offer theoretical guidance for the implementation of the centrifugal granulation process in the treatment of metallurgical slag. (c) 2025 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Methane reforming with carbon dioxide by utilizing the high temperature blast furnace slag is an effective way for waste heat recovery and energy conservation. Three typical oxides, CaO, MgO, and Fe2O3, are selected to present the active components of blast furnace slag, and the effects on CH4/CO2 reforming process are investigated by using ReaxFF-MD and DFT simulation methods. The reaction behaviors of different systems under different conditions are revealed and discussed. The participation of CaO, MgO and Fe2O3 induces new reaction pathways for the CH4/CO2 reforming system, reduces the energy barrier of various reaction steps, and decreases the overall activation energy of CH4/CO2 reforming process remarkably. The energy barrier of the additional reaction caused by CaO is as low as 49.3 kJ/mol. The overall activation energy of the reforming reaction under the addition of Fe2O3 is reduced to 110.41 kJ/mol. However, the presence of blast furnace slag components may provide excess oxygen into the system, induces more types and amounts of by-products, and may decrease the yields of CO and H2 in the system. The ratios of CH4/CO2 and gas/slag should be adjusted and optimized for the practical CH4 reforming process by using the waste heat of blast furnace slag to achieve a high reaction rate as well as high yields of CO and H2.

Molten magnesium chloride (MgCl2), a high-temperature by-product from titanium metal production, currently results in substantial thermal energy loss and environmental issues during conventional cooling. This research investigates rotary cup granulation technology to recover this significant waste heat and enhance the overall process safety and environmental performance. The study experimentally examined the breakup dynamics of molten MgCl2 at the rotary cup's edge, evaluating the influence of rotation speed, cup diameter, and mass flow rate on granulation characteristics. Principal findings indicate that rotary cup granulation effectively forms small, uniform spherical particles, predominantly ranging from 0.6 to 1.5 mm. At a rotating speed of 800 rpm, particle uniformity was optimal, with a standard deviation (S-value) below 0.245, suggesting favourable sphericity. Increasing mass flow rate, however, led to larger, less uniform particles and undesirable flake formation. This granulation process is foundational for enhancing waste heat recovery, as the resulting small and uniform spherical particles (0.6-1.5 mm) provide a large surface-area-to-volume ratio, making them an ideal medium for efficient heat transfer in subsequent recovery systems.

Climate change posed the greatest threat to human sustainable development, and reducing carbon emissions was a pressing issue for all humanity. Among the most energy-intensive and carbon emissions industries, the iron and steel industry (ISI) represented almost 5% of energy consumption and 7% carbon emissions around the world. The ISI faced severe challenges from the “relative constraints” of carbon emissions intensity to the “absolute constrains” of total carbon emissions. Waste heat played an indispensable role in the low-carbon development of ISI. The heat contained in the blast furnace slag (BFS) was considerable, and it was an important position to be occupied. In recent decades, the proposal and development of dry centrifugal granulation (DCG) technology had provided researchers with great encouragement and brought the dawn to overcome the problem of slag waste heat recovery. This technology had been hailed as one of the most suitable technologies to boost sustainable transition of the ISI. This paper provided a detailed review of DCG technology including granulation characteristics of BFS, flight and impingement behavior of slag particles, slag transformation in granulation chamber, waste heat recovery process, etc. Furthermore, the implementation and technical characteristics of semi- and industrialization implementation for DCG technology were explored and elaborated as comprehensively as possible. Ultimately, the problems existing in the development of this technology were analyzed, and suggested the future direction and challenges. This paper aiming to pave the way for the waste heat recovery of BFS while supporting the market penetration and enhancing the role in the fight against climate change for ISI.

本工作以羧甲基纤维素钠作为增稠剂,并分别以十二水磷酸氢二钠、无水磷酸氢二钠、纳米Al2O3及经十二烷基硫酸钠改性的纳米Al2O3作为成核剂,以石墨作为导热增强剂,采用熔融共混法制备出一系列复合相变材料(composite phase change materials,CPCMs).通过红外光谱仪、扫描电镜、差示扫描量热仪和温度采集系统对CPCMs的成分、形貌和热性能等进行综合分析,结果显示,在三水乙酸钠基体中添加2％羧甲基纤维素钠/3％十二水磷酸氢二钠或2％羧甲基纤维素钠/1％改性纳米Al2O3能有效解决SAT相分离和过冷度大的问题,DSC分析结果显示CPCMs的相变焓维持在247.98 J/g和244.64 J/g的水平.在三水乙酸钠基体中加入2％羧甲基纤维素钠/3％十二水磷酸氢二钠/1％石墨或2％羧甲基纤维素钠/3％十二水磷酸氢二钠/1％改性纳米Al2O3/1％石墨能在不提高过冷度的同时增强CPCMs的导热能力,对CPCMs进行了快速循环蓄放热实验,通过T-history法计算相对潜热的变化,结果发现,随着循环次数的增加,前者热衰减率不断增加,在循环次数达到40次后趋于稳定,热衰减约23％,而后者在经过50次循环后过冷度有增加的趋势.本研究有助于推动相变材料在储热领域的应用,并为高焓值和高稳定性三水乙酸钠复合相变材料的研发提供实验依据.

Centrifugal granulation with waste recovery was proposed to recover the waste heat from the molten yellow phosphorus slag produced by an electric arc furnace and reduce pollution. The yellow phosphorus slag was heated to the same temperature as industrial electric furnaces and then granulated by centrifugal granulation. The study mainly investigated the effect of operating parameters on particle diameter distribution, flight distance distribution, and fiber mass fraction during the granulation process. The results showed that the average diameter was mainly 1.5-3 mm, and tended to decrease with the decrease of the mass flow rate, the increase of the rotating speed, and the increase of the rotary cup diameter. The particle diameter obeyed a log-normal distribution. As the rotating speed increased and the rotary cup diameter increased, the average flight distance and the distribution of flight distance were dispersed. The average flight distance was related to the linear velocity at the edge of the rotary cup. Increasing slag temperature, mass flow rate, and decreasing rotary cup diameter can reduce the fiber mass fraction. Re and We numbers can determine whether fibers produce. & COPY; 2023 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

转杯粒化法是当前最具发展前景的一种熔渣干法粒化技术,但粒化过程中产生的丝状物极不利于粒化设备的稳定运行,这限制了该技术的产业化.本文中通过黄磷渣转杯粒化热态实验,研究了熔渣温度、熔渣流量、转杯直径及转杯转速对粒化产物中丝状物生成量的影响.结果表明:随着熔渣温度的升高,丝状物占比减少,当熔渣温度低于 1325℃时,丝状物占比超过 5％;随着熔渣流量的增加,丝状物占比也减少,当熔渣流量在 0.2 kg/s以上时,丝状物占比不超过 5％;在相同的转杯边缘线速度下,转杯直径越大,粒化产物中丝状物占比越高.此外,建立了丝状物占比的预测模型,可为熔渣转杯粒化工艺参数的选择提供理论指导.

采用转杯粒化法将氯化镁破碎成小颗粒并进行余热回收,利用Fluent软件模拟研究了粒化后熔滴的冷却行为,以SST k-ω湍流模型和焓法模型为基础,分析了熔滴直径、初始速度及初始温度对熔滴冷却行为的影响规律.结果表明:氯化镁熔滴的直径越大,表面凝固时间和完全凝固时间越长,凝固速率的变化在凝固后期比凝固前期越小;熔滴的初始速度越大,凝固速率越快,表面换热能力越强,但换热能力的增幅随着初始速度的增大而下降;熔滴初始温度与完全凝固时间的相关性并不大,但较高的初始温度会延长熔滴表面凝固的时间.该研究结果可为转杯粒化氯化镁装置的结构设计提供参考.

针对难以确定制取铁合金一定粒径下的工艺参数,基于飞溅板雾化原理,引入圆盘边缘处液膜厚度和流速为中间变量,将全过程分为圆盘内铺展和圆盘外破碎两个连续阶段,在圆盘内液膜铺展阶段建立气-液两相流数学模型,在圆盘外液膜破碎阶段建立液膜表面扰动波数学模型,研究了液流流速、液流直径和圆盘直径对液膜铺展及破碎特性的影响规律.结果表明,当介质为Sn-58Bi,液流流速为3 m/s,圆盘直径为200 mm,改变液流直径为50～100 mm时,形成液滴直径为7.5～10 mm;液流直径增加或圆盘直径减小时,破碎形成的液滴直径增大;液流流速增加时,液膜破碎时刻提前,对液滴直径的影响较小.

The chromium, iron or zirconium oligomer cations pillared interlayered montmorillonite supported 10 wt% MnOx were synthesized and studied for the flue gas NOx removal in metallurgical sintering process. The physicochemical properties of these catalysts were detected by some characterization methods, such as XRD, N-2 adsorption-desorption, SEM, H-2-TPR, and NH3-TPD. The Mn/Zr-PILM catalyst had the highest NOx conversion with 91.8% at 200 degrees C. And the Mn/Fe-PILM catalyst had the highest NOx conversion between 140 degrees C and 160 degrees C. This is because zirconium or iron pillared montmorillonite increases the specific surface area and acidic sites of catalyst, which provided more adsorption sites and activation sites for NO and NH3, thus promoting low-temperature catalytic activity. The XRD results expressed that the pillared elements successfully pillared into Na-montmorillonite and the manganese active components had good dispersibility on the surface of catalyst. The N-2 adsorption-desorption isotherm indicated that the metal pillared carrier had fractured mesoporous structure and the specific surface area was increased. The Mn/Zr-PILM and Mn/Fe-PILM catalyst had abundant acidity with 61.56 mu mol/g and 57.71 mu mol/g, respectively. The large amount of acid sites favored the adsorption of ammonia in the Langmuir-Hinshelwood or Eley-Rideal mechanisms in the low-temperature NH3-SCR process. The Mn/Fe-PILM catalyst had the best N-2 selectivity and Mn/Cr-PILM has poor N-2 selectivity. This was due to that iron element restrains the side reaction for N2O production and chromium promoted the N2O production by strong oxidation.

采用离散元法(DEM)对封闭的管式太阳能集热器内颗粒与换热管的换热过程进行研究,模拟不同的管型和管间距对换热性能的影响.结果表明,不同管型的换热效果有较为明显的差距.菱形换热管在水平间距63.25 mm、垂直间距63 mm时有最好的换热性能;六边形换热管在不同的空间排布下均有较好的换热性能;组合圆形换热管在水平间距51.96 mm、垂直间距54 mm时有最高的颗粒出口温度,但出口处颗粒流量最小,总换热量也较小.

文章以固体热载体热解煤工艺为研究背景,采用离散单元法对热载体颗粒与煤颗粒在挡板颗粒混合器中的混合过程进行数值模拟研究.探究挡板混合器结构、热载体粒径和热载体与煤的进料比等因素对混合度的影响.结果表明:采用挡板与壁面夹角30°、相邻挡板旋转60°放置的结构可有效提高混合度;由于颗粒的混合与离析同时存在,通过提高煤的进料比,采用0.004 m大粒径热载体可减弱离析影响,增强混合均匀度.

富氧燃烧技术具有提高理论燃烧温度,加快火焰传播速度,增加反应速率等优点.混合煤气是钢铁工业的常用燃料,研究富氧工况下混合煤气可燃极限的变化规律,可以为相关燃烧器的设计和操作参数的设定提供参考,也为混合煤气的安全使用提供基础数据,从而减少能源浪费.本文使用5 L圆柱形密闭容器进行实验,测量了助燃气氧气浓度下的可燃极限.结果表明:随着氧气浓度的增加,混合煤气的可燃下限从15％升高到16％,变化规律近似线性;可燃上限从36.75％升高到88.25％,变化规律呈抛物线形.

自流床余热锅炉回收高炉渣颗粒余热的过程,实质上就是高温颗粒绕流圆管的流动与传热过程. 采用MFiX软件对高炉渣颗粒绕流圆管的传热过程进行数值模拟,研究了颗粒出口流速和圆管排列方式对传热特性的影响. 结果表明:随着颗粒出口流速的增加,颗粒的温降速率和换热管的局部热流密度均增大;与换热管顺排排列相比,叉排排列时的管间颗粒温度分布和换热管的局部热流密度分布更加均匀,颗粒温降速率也更大.

液态氯化镁是Kroll法生产海绵钛过程中产生的副产品,排出温度为820～890℃,具有很高的利用价值.目前,镁电解是最为成熟的液态氯化镁回收工艺,但其高昂的投资和运行成本限制了该项技术在我国的发展,大量的液态氯化镁经自然冷却后被低价出售.回顾了国内镁电解技术发展历程,并详细介绍了液态氯化镁回收的最新技术,原位热解-热法还原方法以及液态氯化镁余热回收系统,讨论了2种工艺的特点,以期为企业节能降耗提供参考.

采用开源软件MFIX的CFD-DEM耦合法,对以高炉渣颗粒作为移动热载体的气化系统进行模拟研究,主要考察了气化剂流速、焦炭直径对颗粒速度、颗粒温降、CO质量分数的影响规律.研究结果表明:颗粒的速度会随着气化剂流速的增大而增大二者呈线性关系.颗粒的温降随着气化剂流速的增大而减小,出口气体温度随着气化剂流速的增大而增大,出口气体中CO的质量分数随着气化剂流速的增大而减少,当流速为0.4,1.4 m/s时,出口气体中CO的质量分数分别为89％,45％.减小焦炭直径有助于加快气化速率,出口气体中CO的质量分数随着焦炭直径的减小而增大.

根据国家环保发展形势和铁路货车涂装现状,开展了铁路货车用水性涂料的工艺研究和推广应用,结果表明水性涂料代替溶剂型油漆,可提高铁路货车的防护能力和外观质量,并具有优异的环保性和安全性.

根据国家环保发展形势和铁路货车涂装现状,开展了铁路货车用水性涂料的工艺研究和推广应用,研究了水性涂料的技术标准、施工工艺、环境友好和安全性能,开展了符合性设备改造、样车试用和推广应用工作.结果表明:制备的水性涂料可提高铁路货车的防护能力和外观质量,并具有优异的环境友好性和安全性,用在铁路货车可替代传统溶剂型涂料.

Water quenched blast furnace slag is an excellent hydrated material. However, dry granulation is a new treatment method for molten blast furnace slag that has numerous advantages compared to water quenching. This study investigated the size distribution of slag particles obtained from the dry granulation of molten slag. In addition, the effect of using the slag obtained from dry granulation in slag cement blends was analyzed. All the results showed that there was a wide size distribution range of blast furnace slag particles in ligament formation. The mean diameter of the solid particles decreased as the rotating speed increased. Meanwhile, the glass content in slag particles decreased for a fixed diameter of the metal collecting tray. The strength of slag cement concrete was low at a low rotating speed. In contrast, obtaining slag particles at a high rotating speed was beneficial for producing a compact structure in the slag cement blend.