Short Flow Research Articles

Numerical Simulation of Gas-Solid Two-Phase Heat Transfer in a Kaolin Cyclone Cooling System

The kaolin suspension calcination technology is currently gaining attention as a new process of calcining kaolin. In this paper, the cooling system of the kaolin suspension calcination process designed by CBMI Construction Co., Ltd. is simulated using ANSYS Fluent software to analyze the velocity field and temperature field of the gas–solid two-phase flow using the Eulerian model. A compiled UDF (User-Defined Function) is used to simulate the transfer of mass and heat from the downcomer tube to the different elements. The gas, coming from the gas outlet of the cyclone, enters the next level twin-cylinder cyclone in a spiral state. The results show that the airflow in the cyclone consists of an external spiral flow from the top to the bottom and an internal spiral flow from the bottom to the top. During the downward movement of the airflow, the outer spiral flow is continuously transformed into an inner cyclonic flow. The part of the airflow that rotates close to the inner cylinder is likely to become a ‘short circuit flow’, which largely affects the separation efficiency and cooling effect of the cyclone. There is evident temperature deviation and flow deviation in the twin-cylinder cyclone, which is primarily due to the high cooling air volume and high rotation of air flow coming from the gas outlet of the previous level’s cyclone. The rotation of the air flow is the main cause of the bias temperature and bias flow phenomenon in the twin-cylinder cyclone.

Flow and outdoor adventure recreation: Using flow measures to re-examine motives for participation

Adventure participants have traditionally been viewed as having thrill or risk-seeking motives, and this perception remains despite empirical research suggesting that other motives may drive participation. This study was conducted to extend understanding of participation motives of adventure recreation participants in relation to Csiksentmihalyi’s nine-dimension model of flow and other proposed motivational constructs. Participants (n = 199) who had typically engaged in their adventure recreation activity (i.e., highlining, rock climbing, downhill mountain biking, freefalling, snow sports) regularly, and with considerable competence, took part in this investigation by completing self-report measures of dispositional flow (The Dispositional Flow Scale; DFS-2), state flow (The Short Flow State Scale; SFSS), and participation motives in their adventure recreation environments. Support was observed in confirmatory factor analytic procedures for the factorial validity of DFS-2 and SFSS data obtained from adventure recreation participants. Mean scores from measures on participant experience of flow in adventure recreation were generally found to be significantly higher than previously observed in other physical activity domains, with some differences also being observed among adventure recreation subgroups. Contrary to traditional explanations of adventure recreation participation, risk-seeking was not supported as a key underlying motive by participants in this study. Mastery of one’s adventure recreation activity, perceived connection to one’s activity, and trust in one’s skills, were identified as important participation motives. This study demonstrated that the DFS-2 and SFSS were able to satisfactorily assess flow constructs in adventure recreation, and supported recent research demonstrating flow to be a relevant experience to this setting. The implications of these findings for theory, practice, and future research directions in adventure recreation are discussed.

Efficient recycling of silicon cutting waste for producing high-quality Si-Fe alloys.

A tremendous amount of silicon cutting waste (SCW) is being produced during slicing Si ingots, which leads to a great waste of resources and serious environmental pollution. In this study, a novel method that recycling SCW to produce Si-Fe alloys was proposed, which not only provides a process with low energy consumption, low cost, and short flow for producing high-quality Si-Fe alloys but also achieves a more effective recycling of SCW. The optimal experimental condition is investigated to be a smelting temperature of 1800°C and a holding time of 10min. Under this condition, the yield of Si-Fe alloys and the Si recovery ratio of SCW were 88.63% and 87.81%, respectively. Compared with the present industrial recycling method that uses SCW to prepare metallurgy-grade Si ingot by an induction smelting process, this Si-Fe alloying method can achieve a higher Si recovery ratio of SCW at a shorter smelting time. The promoting mechanism of Si recovery by Si-Fe alloying is mainly expressed as follows: (1) facilitating the separation of Si from SiO2-based slag; (2) reducing the oxidization and carbonization loss of Si by accelerating the heating of raw materials and reducing the exposed area of Si.

Short-Flow Rolling Process and Heat Treatment of Seamless Titanium Alloy Tube

In view of the material characteristics of titanium alloys, such as their capability to quickly cool down and their poor machinability, in this study, we combined a new production mode for seamless tube rolling (tandem skew rolling, TSR) with titanium alloy materials and conducted systematic research. The most suitable parameters for titanium alloy rolling were determined from the unit parameters using finite-element software and an analysis of the changing laws of stress-strain, temperature, speed and tension during the rolling process. A rolling experiment was completed in the tandem skew rolling unit. Seamless titanium alloy (TC4ELI) tubes with uniform wall thickness were successfully produced and a metallurgical heat-treatment experiment was carried out. The results show that the seamless titanium alloy tubes prepared using the TSR process have a high degree of dimensional precision (the outer diameter is approximately 38.7 mm, the wall thickness is approximately 3.9 mm and the axial extension is 2.9 times) and the tube after heat treatment still presented a basketweave structure. Furthermore, the hardness level of the seamless titanium alloy tubes was improved. It can be concluded that the TSR process with a short flow is suitable for the mass production of seamless titanium alloy tubes.

Packet rank-aware active queue management for programmable flow scheduling

Flow scheduling is crucial in improving network Quality of Service (QoS). According to different optimization goals, many scheduling algorithms (e.g., STFQ, pFabric, SRPT, WFQ) have emerged in network. However, these scheduling algorithms are bound with hardware, which are only applicable to fixed network scenarios. Push-In First-Out (PIFO) queues are proposed as a queue abstraction to support programmable packet scheduling, but implementing them in hardware is difficult. We present a general framework named PR-AQM, which uses limited number of FIFO queues to approximate PIFO behavior. The core idea of PR-AQM is to perform Active Queue Management (AQM) on programmable data plane by capturing packet rank distribution and queue congestion level in real time. Specifically, PR-AQM can dynamically adjust the mapping between packet ranks and queues according to the delay status of different priority queues, thus efficiently achieving priority scheduling of packets. We carry out extensive simulations and implement PR-AQM prototype in Tofino switches to evaluate the performance of PR-AQM. Experimental results show that compared with state-of-the-art algorithms, PR-AQM can adapt well to different scheduling algorithms, and achieve better performance by reducing the average flow completion time for short flows up to 45%.

Dynamic Relationship Between External Financial Flows and Total Market Capitalization in The Nigerian Capital Market: VECM Approach

The study examines the extent to which external financial flows influence market capitalization of Nigerian capital market for the period spanning 1981-2020. The study employed the VECM, regressors’ and ECT t-statistics causality approaches to establish the strong, short-run and long-run relationships. The study unveiled that all the external financial flows such as FDI, FPI, remittance and others used in this study have positive impacts on total annual market capitalization in the Nigerian capital market, especially in the long-run. The stock indices movement is respective to the change in external financial flows basic. The study suggested that the policy measures aimed at directing long run capital inflows should not be the same as those aimed at changing the short run patterns of flow. The study concludes that policy should be put in place to ensure the directions of both long run and short run financial flows have a suitable time rage.

The Relationship between Short Video Flow, Addiction, Serendipity, and Achievement Motivation among Chinese Vocational School Students: The Post-Epidemic Era Context

Since the COVID-19 outbreak, people have been spending more time in the online world because of restrictions on face-to-face communication due to epidemic prevention controls. This has also brought the issue of Internet addiction, including the overuse and negative effects of short videos, to the forefront of attention. Past research has found that Internet addiction has a negative impact on well-being. However, there is a special concept of positive emotion called "serendipity" (). Serendipity provides a small, fleeting but positive experience, yet it is often associated with negative perceptions from an outside perspective. However, the relationship between short video addiction and serendipity is not yet known. Based on this, a theoretical model was developed in the context of the I-PACE model. To understand the relationship between short video addiction and serendipity among college students, in this study, we conducted snowball sampling and distributed online questionnaires using the Wenjuanxing platform. The target population of the questionnaire distribution was vocational college students in China, of whom 985 valid study participants responded, yielding a valid return rate of 82.1%. Of the respondents, 410 (41.6%) were male and 575 (58.4%) were female. The results were as follows: a. short video flow had a positive relationship with serendipity, a negative relationship with achievement motivation, and a positive effect on short video addiction; b. short video addiction had a positive effect on serendipity and a negative effect on achievement motivation; and c. serendipity had a negative impact on achievement motivation. This shows that short video addiction, like other Internet addictions, can have a negative impact on students' learning.

Precision in Defining Diagnostic Plots Optimizes Well-Test Results

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 206108, “Diagnostic Plots of Pressure-Transient, Rate-Transient, and Diagnostic Fracture Injection/Falloff Tests,” by David Craig, SPE, Occidental, and Thomas Blasingame, SPE, Texas A&M University. The paper has not been peer reviewed. _ All transient-test interpretation methods use diagnostic plots for the identification of wellbore or fracture storage distortion, flow regimes, and other parameters. The associated diagnostic plots are not interchangeable between such tests. The objective of this work is to clearly define the appropriate diagnostic plots for each type of transient test. Introduction In the complete paper, the authors review constant-rate drawdown solutions for a few specific cases of interest and the plotting function used to match buildup data to the drawdown solutions. They extend their review to the cases of buildup or falloff analysis following short flow periods and illustrate the differences between analysis of buildup or falloffs following short and long flow periods. After covering pressure-transient testing, they discuss rate-transient diagnostic plots and the ambiguity observed during analysis of multifractured horizontal well diagnostic plots and the uncertainty of analyst straight lines. Finally, they discuss and demonstrate the correct plotting functions and flow-regime interpretation for diagnostic fracture injection and falloff tests. Multiple examples from the literature are included as part of the discussion. Pressure-Transient Diagnostic Plots Pressure-transient-testing diagnostic plots evolved from the solutions to constant-rate drawdown problems. The authors’ intent is to review infinite-acting solutions for radial flow with wellbore storage and skin and flow through an infinite-conductivity fracture. On a log-log plot, the characteristic slopes, detailed in the complete paper, are unit slope, ½ slope, and zero slope. Many authors have proposed plotting functions for overlaying the observed pressure response from transient tests other than a constant-rate drawdown on the drawdown solutions. In many cases, the slopes identifying storage distortion and flow regimes from drawdown solutions will match and can be used to identify storage and flow regimes from pressure-buildup tests. A situation in which pressure-buildup or falloff test plotting functions fail to match the drawdown solution is when the flow period before shut-in is short. Short-flow transient tests have been reviewed by multiple authors. In lower-permeability reservoirs, pressure-transient tests with short flow periods are very common, and, in unconventional reservoirs, short-flow transient tests are the most-common transient test. Diagnostic plots constructed based on the characteristic shapes of the dimensionless pressure and the dimensionless pressure derivative with respect to the natural logarithm of dimensionless time for constant-rate drawdown solutions cannot be applied in the same manner for short-flow transient tests. With short-flow transient tests, the observed derivative of pressure difference with respect to the natural logarithm of time matches the negative product of dimensionless time and the second derivative of dimensionless pressure with respect to dimensionless time. Additionally, the commonly known impulse derivative, which is defined as the product of time and the derivative of pressure difference with respect to the natural logarithm of time, will match the negative product of dimensionless time squared and the second derivative of dimensionless pressure with respect to dimensionless time.

Preclinical evaluation of the fluid dynamics and hemocompatibility of the Corheart 6 left ventricular assist device.

Corheart 6 (Corheart) is a newly developed magnetically levitated continuous-flow left ventricular assist device currently undergoing multicenter clinical trials in China. Featuring a small size, minimal weight, and low power consumption, the Corheart aims to improve pump hemocompatibility, reduce adverse events, and enhance the quality of life of heart failure patients. Computational simulations assessed flow field, shear stress, and washout, while in vitro and in vivo experiments were performed to further demonstrate hemocompatibility. Numerical results show that the flow path in the Corheart blood pump is well designed. There is no significantly high shear stress in the majority of the flow domain. Short secondary flow paths and small pump size (small priming volume) provide good washing (0.049 and 0.165 s to remove 55% and 95% old blood, respectively), allowing low hemolysis levels both in computational and in vitro hemolysis tests (in vitro hemolysis index ranges from 0.00092 ± 0.00006 g/100 L to 0.00134 ± 0.00019 g/100 L). Good hemocompatibility was further evidenced by ten 60-day sheep implants tested with relatively low flow rates of 2.0 ± 0.2L/min; the results showed no hemolysis or thrombosis. Numerical and experimental results shed light on the fluid dynamics characteristics and hemocompatibility of the Corheart. It is believed that the Corheart will provide more promising possibilities for minimally invasive implantation techniques and for those patients with a small body surface area.

Measuring optimal psychological states: Proposal of two brief versions to measure flow and clutch in athletes.

The study of sports experiences with high levels of performance has led to the observation of two psychological states categorized as optimal, denominated flow and clutch. The objective of this study is to design and validate two brief scales version to measure flow and clutch. Following the MIMO (Maximum Information, Minimum Discomfort) protocol, three studies are carried out: In Study 1, we developed the short versions of the questionnaires based on theory-driven and data-driven criteria; in Study 2, we used quantitative criteria to validate the short versions; and in Study 3, we checked the final version of each scale to observe their statistical validity and their relation to other variables. The new short flow scale is made up of seven items, while the clutch scale is made up of five items. Throughout the three studies, evidence is provided of the internal consistency, invariance of the measurement models and content validity, validity related to the responding process and validity in relation to other variables. This study provides two short versions to evaluate flow and clutch, which will help to continue advancing in the study of optimal psychological states in sport.

CFD supported scale up of perfusion bioreactors in biopharma

The robust scale up of perfusion systems requires comparable conditions over all scales to ensure equivalent cell culture performance. As cells in continuous processes circulate outside the bioreactor, performance losses may arise if jet flow and stirring cause a direct connection between perfusion feed and return. Computational fluid dynamics can be used to identify such short circuit flows, assess mixing efficiencies, and eventually adapt the perfusion setup. This study investigates the scale up from a 2 L glass bioreactor to 100 L and 500 L disposable pilot scale systems. Highly resolved Lattice Boltzmann Large Eddy simulations were performed in single phase and mixing efficiencies (Emix) furthermore experimentally validated in the 2 L system. This evaluation gives insight into the flow pattern, the mixing behavior and information on cell residence time inside the bioreactors. No geometric adaptations in the pilot scale systems were necessary as Emix was greater than 90% for all conditions tested. Two different setups were evaluated in 2 L scale where the direction of flow was changed, yielding a difference in mixing efficiency of 10%. Nevertheless, since Emix was confirmed to be >90% also for both 2 L setups and the determined mixing times were in a similar range for all scales, the 2 L system was deemed to be a suitable scale down model. The results demonstrate how computational fluid dynamic models can be used for rational process design of intensified production processes in the biopharmaceutical industry.

Enhancing Security by Using GIFT and ECC Encryption Method in Multi-Tenant Datacenters

Data security and user privacy have become crucial elements in multi-tenant data centers. Various traffic types in the multi-tenant data center in the cloud environment have their characteristics and requirements. In the data center network (DCN), short and long flows are sensitive to low latency and high throughput, respectively. The traditional security processing approaches, however, neglect these characteristics and requirements. This paper proposes a fine-grained security enhancement mechanism (SEM) to solve the problem of heterogeneous traffic and reduce the traffic completion time (FCT) of short flows while ensuring the security of multi-tenant traffic transmission. Specifically, for short flows in DCN, the lightweight GIFT encryption method is utilized. For Intra-DCN long flows and Inter-DCN traffic, the asymmetric elliptic curve encryption algorithm (ECC) is utilized. The NS-3 simulation results demonstrate that SEM dramatically reduces the FCT of short flows by 70% compared to several conventional encryption techniques, effectively enhancing the security and anti-attack of traffic transmission between DCNs in cloud computing environments. Additionally, SEM performs better than other encryption methods under high load and in large-scale cloud environments.

RDMA Congestion Control: It Is Only for the Compliant

Remote direct memory access (RDMA) networks enable low latency and low central processing unit utilization, and their widespread adoption in datacenters enables improved application performance. However, there are performance isolation concerns for RDMA deployed in a shared cloud environment. In particular, congestion control enforcement and congestion control algorithms in RDMA make the network susceptible to performance hacking attacks, which give the attacker extra bandwidth and cause severe congestion in the network. These attacks can increase short flow completion times by several orders of magnitude. We surface a fundamental tradeoff in congestion control between short flow completion time and performance isolation. We discuss this tradeoff and how existing approaches do not provide a robust solution. We also advocate that researchers incorporate performance isolation concerns into the design and evaluation of congestion control.

Synthesis of ultrafine (Mo,W)Si2 composite powders from high purity molybdenum concentrate

(Mo,W)Si2 composite powders with the grain size of about 1 ?m were synthesized at 1150? for 2 h. The high purity molybdenum concentrate (with the main component of MoS2), W and Si powders were utilized as raw materials and lime as desulfurizer. The graphite felt was laid between the compact (made of MoS2, W and Si) and the lime to facilitate the separation of the produced composite powders from desulfurization product. The phase composition, microstructure evolution, and residual sulfur content during the silicothermic reduction reaction were evaluated. The experimental results showed that the reaction could be completed after a reaction time of 1150? for 2 h, and the residual sulfur content of the product was 0.087 wt.%. It was concluded that the interactions between Si and the intermediate products of SiS and SiS2 are crucial for the preparationof (Mo,W)Si2 composite powders at low temperatures. The preparation process could be divided into three stages: solid state reactions between MoS2, W and Si to produce MoSi2, WSi2 and gaseous SiS; gas-solid reaction between MoS2, W and gaseous SiS to generate MoSi2, WSi2 and gaseous SiS2; and gas-solid reaction between gaseous SiS2 and Si to form SiS gas. With this short flow process, fine-grained (Mo,W)Si2 composite powders can be produced at low cost at low temperature, which has great application potential.

Effects of helical fins on the performance of a cyclone separator: A numerical study

This study aimed to investigate the separation performance of a cyclone separator after reshaping its cylindrical body by installing the helical triangular fins. A numerical simulation based on Fluent was adopted to perform an orthogonal test to optimise the structure of the cyclone separator with helical triangular fins. Three structural parameters of the helical triangular fins were selected as optimisation variables: base width, fin size, and fin pitch, and their influences on the evaluation indices of the cut-off diameter were investigated. The optimal combination scheme was determined by range analysis, and the cyclone separator performances before and after optimisation were compared and analysed. The significant influence of the structural parameters on the cut-off diameter was in descending order as the fin pitch, fin size, and base width. For particles with diameter of 0.1, 0.5, 1, 2, and 3 μm, the separation efficiency of the cyclone separator with optimized helical triangular fins increased by 7.4 %, 15.9 %, 20.1 %, 10.9 % and 14.8 % respectively. Moreover, the cut-off diameter of the finned cyclone separator is reduced by 30.7 %, while the pressure drop is only increased by 6.6 %. The short circuit flow and back-mixing were alleviated, thereby considerably enhancing the stability of the flow field. Therefore, the finned cyclone separator was found to play a critical role in increasing the separation of fine particulate matter.

BBR-With Enhanced Fairness (BBR-EFRA): A new enhanced RTT fairness for BBR congestion control algorithm

Towards the end of 2016, the Google research team proposed and developed a new state-of-the-art TCP congestion control algorithm called Bottleneck Bandwidth and Round-trip propagation time (BBR). When deployed on various Google internal servers, BBR attained higher throughput and low latency performances on modern-day and sophisticated networks than traditional congestion control algorithms like Cubic, Reno, or Vegas. Unlike conventional congestion control algorithms, BBR controls data transmission by maximizing delivery rate and minimizing the round-trip time (RTT), therefore maximizing bandwidth utilization and improving throughput and latency delay performances. However, some experiments have reported persistent queue formation and massive packet retransmissions rate in the bottleneck link, which happens to be the main cause of unfairness between different RTT flows. BBR prefers and favors long RTT over short RTT flows; therefore, long RTT flows are allocated more bandwidth when competing with short RTT flows in the bottleneck link. It was also noted that even the minor difference between the two competing flows could be a source of throughput imbalance and unfairness. The dominance of long RTT flows is the central origin of the high queuing delay, packet loss and retransmission rates, and even severe BBR vulnerability that malicious users can exploit to obtain a larger share of bandwidth simply by increasing the RTT (delay). Therefore, we propose a BBR-With Enhanced Fairness (BBR-EFRA) to mitigate this major concern challenge. Our proposed algorithm adaptively controls the congestion window (CWND) by adjusting the bandwidth delay product (BDP) values of each BBR flow during data transmission based on buffer queue status computation. Our proposed approach guarantees different RTT flows to compete for the available bottleneck bandwidth more equally, hence improving the BBR fairness issue. We evaluated our algorithm on the NS3 simulating environment. BBR-EFRA shows improved RTT fairness by more than 16%, reduced retransmission rate by more than 20%, and queuing delay by more than 18%, and finally increased Jain’s fairness index by more than 1.3 times compared with other recently published BBR variants like an adaptive congestion window of BBR(BBR-ACW). Therefore, with BBR-EFRA, short RTT flows can fairly compete for the available bandwidth even with higher RTT differences under various network scenarios.

Risk scenarios for a future eruption in the Chichinautzin monogenetic volcanic field, South México City

The Chichinautzin Monogenetic Volcanic Field creates volcanic risks for México City. To evaluate the possible effects and economic impacts of a future eruption, three scenarios based-on the spatial distribution of the most recent eruptions and the study of their characteristic are proposed. Scenario A, a Violent Strombolian eruption at the northwestern edge of the volcanic field, with eruptive columns 6–8 km high and emission of low-viscosity lava flows. Scenario B, Santiaguito-type eruption, a thick, high-viscosity lava flow that generates rock falls and short Merapi-type pyroclastic flows in the central northern area. Scenario C, a Hawaiian to Strombolian eruption with eruptive columns <6 km high and the emission of low viscosity lavas in the central part of the field. From these scenarios, numerical simulations of lava and tephra were carried out to obtain conditional hazard maps. The risk evaluation integrates the analysis of hazard, exposure, vulnerabilities, resilience, and the estimation of the costs of possible damages with physical and sociodemographic indicators available at the city block level, including rural areas. Two vulnerability curves were integrated for housing, the first for lava flows, which considers that a thickness ≥ 2 m of lava causes total loss (considering the loss of the function and accessibility); and a second curve for tephra that considers that an accumulated thickness in dry conditions of 20 cm of tephra produces generalized damage to all type of houses. By combining the vulnerability and hazard maps, two risk maps were constructed, one for lava flows and the other for tephra. The total direct cost of the expected damages was calculated for each scenario considering the cadastral value of the land and buildings for each property at risk. The costs for the most probable and the most catastrophic scenario amount to >14 billion US dollars, equivalent to 1.2% of the national GDP. Mitigation measures, mainly of the non-structural type are proposed.

Molecular dynamics simulations of unsteady evaporation of thin liquid argon layer into a vacuum

The unsteady evaporation of liquid argon layer into a vacuum was studied based on molecular dynamics technique using the LAMMPS package. The comparison of the mass flow rate with the known kinetic theory analytical equations was carried out for several temperatures of the liquid layer. It was obtained that after short relaxation time mass flow rate ceases to depend on time for some period. The relaxation time for mass flow rate was estimated. It turned out that this time depends on the temperature of the liquid layer and decreases with increase of its temperature. The mass flow rate values predicted by molecular dynamics simulation are found to be well described by some analytical formulas from kinetic theory. The temporal dynamics of the liquid layer was investigated. The linear dependence between film thinning rate and mass flow rate values was obtained both in the quasi-steady regime and out of it. It was found that liquid interface temperature depends on liquid thickness by power law with an exponent independent of initial liquid film temperature.

Non-isothermal direct bundle simulation of SMC compression molding with a non-Newtonian compressible matrix

Compression molding of Sheet Molding Compounds (SMC) is a manufacturing process in which a stack of discontinuous fiber-reinforced thermoset sheets is formed in a hot mold. The reorientation of fibers during this molding process can be either described by macroscale models based on Jeffery's equation or by direct mesoscale simulations of individual fiber bundles. In complex geometries and for long fibers, direct bundle simulations outperform the accuracy of state-of-the-art macroscale approaches in terms of fiber orientation and fiber volume fraction. However, it remains to be shown that they are able to predict the necessary compression forces considering non-isothermal, non-Newtonian and compaction behavior. In this contribution, both approaches are applied to the elongational flow in a press rheometer and compared to experiments with 23% glass fiber volume fraction. The results show that both models predict contributions to the total compression force and orientation reasonably well for short flow paths. For long flow paths and thick stacks, complex deformation mechanisms arise and potential origins for deviation between simulations models and experimental observations are discussed. Furthermore, Jeffery's basic model is able to predict orientations similar to the high-fidelity mesoscale model. For planar SMC flow, this basic model appears to be even better suited than the more advanced orientation models with diffusion terms developed for injection molding.

Short flow and eco-friendly process for V2O3 preparation via hydrogen-catalyzed solution-phase method

V2O3 is mainly used to prepare ferro-vanadium. The introduction of solution-phase hydrogen reduction (SpHR) can reduce energy consumption, shorten the process and decrease ammonia pollution. In order to improve the hydrogen activity, PdCl2, Ni powder, and anthraquinone were selected as catalysts. Under the optimum condition, the precipitation ratio of product catalyzed by Ni powder was similar to that catalyzed by PdCl2, which were 99.80 % and 99.74 %, respectively. The purity of products met the requirements of GB 40301–2021, and the particle size of product catalyzed by Ni powder was more uniform. The products of SpHR with anthraquinone and auto-catalysis were Na(V2O5) and VO2(H2O)0.5, respectively. The activation energy of reaction catalyzed by PdCl2 and Ni powder were 38.0679 kJ/mol and 140.0909 kJ/mol, respectively. In the process of hydrogen-catalyzed, H2 molecule adsorbs on the surface of Ni or Pd, and form two Me-H bonds with strong reducibility, and its s orbital is hybridized with the d orbital of Pd and Ni. PdCl2 and Ni powder reduced the hydrogen dissociation energy from 434 kJ/mol to 30.3960 kJ/mol and 63.8332 kJ/mol, respectively. The phase transformation of vanadium precipitation by SpHR with the intervention of Ni catalyst is: HV10O285- or V(V) amorphous precipitation → filamentous Na2V6O16·3H2O → irregular flake Na(V2O5) → flaky VO2(H2O)0.5 → cross-like VO2(H2O)0.5 → rhombohedral V2O3.