Effect of mesoscale structures on solid phase stress in gas-solid flows

Solid phase stress plays an important role in hydrodynamic modeling and simulations of gas-solid flows. However, heterogeneous gas-solid flows are typically regarded as homogeneous systems. Their solid phase stresses are usually calculated by the classical kinetic theory of granular flow (KTGF) without considering mesoscale structures, which is a major source of inaccuracies. This work investigates the effect of mesoscale structures in gas-solid flows via a dilute-dense two-phase partition, and proposes a phase-specific model to predict solid phase stress. Subsequently, the sensitive of threshold for phase partition is discussed, and a specific threshold is utilized in the proposed model to investigate the effect of mesoscale structures on solid phase stress with large-scale particle-resolved direct numerical simulation (PR-DNS) data. Numerical results show that classical KTGF underestimates the solid phase stress due to the ignorance of these structures

Effect of mesoscale structures on solid phase stress in gas-solid flows

Solid phase stress plays an important role in hydrodynamic modeling and simulations of gas-solid flows. However, heterogeneous gas-solid flows are typically regarded as homogeneous systems. Their solid phase stresses are usually calculated by the classical kinetic theory of granular flow (KTGF) without considering mesoscale structures, which is a major source of inaccuracies. This work investigates the effect of mesoscale structures in gas-solid flows via a dilute-dense two-phase partition, and proposes a phase-specific model to predict solid phase stress. Subsequently, the sensitive of threshold for phase partition is discussed, and a specific threshold is utilized in the proposed model to investigate the effect of mesoscale structures on solid phase stress with large-scale particle-resolved direct numerical simulation (PR-DNS) data. Numerical results show that classical KTGF underestimates the solid phase stress due to the ignorance of these structures

工业生产全过程减污降碳:方法策略与科学基础

随着我国环境保护排放标准日益严格及行业园区化发展日渐成型,有毒有害污染物稳定达标与碳减排协同治理技术缺乏、末端无害化治理控制成本高等问题,开始严重制约我国社会经济可持续发展和碳达峰、碳中和目标的实现。文章以工业行业的重大环境保护需求为导向,提出工业生产全过程减污降碳的方法策略及科学基础。通过控制方法协同、跨介质协同,以及多领域统筹、多要素统筹建模优化,将分子水平或微观水平上的基础科学创造性发现与工程研究开发直接联系起来,为减污降碳协同增效提供新的科学支撑,为我国工业绿色发展和碳减排贡献理论方法

Cleaner production of ammonium paratungstate by membrane electrolysis-precipitation of sodium tungstate solution

The production of ammonium paratungstate (APT) is riddled with the generation of wastewater,which causes environmental problems.To solve the problem of wastewater generation at source,a membrane electrolysis-NH_3·H_2O precipitation method,which prevents wastewater generation and recycles the reagents used in the process,was proposed and investigated in this study.The electrolysis process was investigated based on parameters such as initial cathodic and anodic NaOH concentrations,and current density.The results showed that an increase in current density and initial cathodic NaOH concentration and a decrease in the initial anodic NaOH concentration would enhance the separation of tungsten and sodium.The optimum condition was found at a current density of 666 A·m~(-2),initial anodic and cathodic NaOH concentrations of 69 g·L~(-1) and 40 g·L~(-1),with a current efficiency of 75.40%,and energy consumption for producing 1 ton of NaOH was 2184 kW·h.The precipitation process was investigated based on the acidic high W/Na molar ratio solution obtained by the electrolysis process with NH_3·H_2O as the precipitant.Parameters such as excessive coefficient,temperature,and W/Na molar ratio were studied.The result showed that the variation of excessive coefficient and solution temperature had an opposite effect on the purity of the APT,while an increase in the W/Na molar ratio would increase the product purity.The precipitation product obtained had a purity of 99.6% and was characterized using X-ray diffraction,inductively coupled plasma,and scanning electron microscopy.The methods proposed in this study could provide fundamental information for the design of a cleaner APT production process

废弃SCR催化剂氧化酸洗除As工艺及机理研究

砷(As)及其他杂质元素是导致燃煤电厂废弃SCR脱硝催化剂失活的主要原因,借助Fenton反应对废弃SCR脱硝催化剂中的有害杂质元素As及Fe、Al进行氧化酸洗脱除,探究了酸洗液种类、酸浓度、氧化剂浓度、反应温度、反应时间、液固比等因素对杂质浸出率的影响。结果表明,最佳的杂质浸出条件为:反应温度为50℃、H_2SO_4浓度为1.5 mol/L、H_2O_2浓度为1.5 mol/L、转速为500 r/min、反应时间为240 min、液固比为20 mL/g,此时As、Fe、Al的浸出率分别为99.58%、41.80%、 39.60%。废弃催化剂杂质元素浸出机理为过氧化氢与被硫酸浸出的Fe~(2+)形成了芬顿试剂,将As~(3+)氧化为As~(5+),使其氧化溶出,提高了As元素的脱除效率

Expression of TFRC helps to improve the antineoplastic effect of Ara-C on AML cells through a targeted delivery carrier

Currently, high doses of cytarabine arabinoside (Ara-C)-based combined chemotherapy are commonly used in acute myeloid leukemia (AML) therapy, but severe adverse effects and poor suppression effects in leukemia cells limit the clinical therapeutic efficiency of Ara-C-based chemotherapy due to a lack of targeting selectivity. To improve the therapeutic effect of Ara-C in AML, here, since we confirmed that transferrin receptor 1 (TFRC) expression in AML cells was constant, we generated Ara-C@HFn by encapsulating free Ara-C into self-assembled heavy ferritin chain (HFn, the ligand of TFRC) nanocages

Aluminum Impurity from Current Collectors Reactivates Degraded NCM Cathode Materials toward Superior Electrochemical Performance

The huge amount of degraded NCM (LiNi0.5Co0.2Mn0.3O2) cathode materials from spent lithium-ion batteries is arising as a serious environmental issue as well as a severe waste of metal resources, and therefore, direct recycling of them toward usable electrode materials again is environmentally and economically more attractive in contrast to present metallurgical treatments. In this work, we design a robust two-step method for direct recycling of degraded NCM materials, which uses the aluminum impurity from the attached current collector to supplement the transition metal vacancies for simultaneous elemental compensation and structural restoration. This single-element compensation strategy leads to the regeneration of high-quality NCM material with depressed cation disordering and stabilized layered structure. Moreover, the regenerated NCM material with controllable Al doping delivered an outstanding electrochemical performance; specifically, the capacity (158.6 mAh g-1), rate capability (91.6 mAh g-1 at 5 C), and cycling stability (89.6% capacity retention after 200 cycles) of the regenerated NCM material are even comparable with those of fresh materials. The as-established regeneration protocol has its chance in simplifying the industrial recycling process of degraded NCM materials