•CFD solver is coupled with a stand-alone GPU-based DEM via network communication.•Communication overhead is insensitive to the number of particles being simulated.•A dual-grid approach is proposed ...for data mapping between Eulerian and Lagrangian properties.•This coupling scheme can handle large-scale, general-purposed industrial applications.•DEM calculation is no longer the computational bottleneck for a coupled CFD-DEM simulation.
High computational cost presents a significant barrier to the general application of coupled computational fluid dynamics and discrete element method (CFD-DEM) simulations, especially so for industrial systems with a large number of particles and complex geometries. In this study, a new cross-platform coupling approach is developed by integrating a CFD solver with a standalone GPU-based DEM solver via network communication. Consequently, the two modelling techniques benefit from the most appropriate hardware architecture. The developed coupling approach shows predictions comparable to experiments on a small-scale fluidized bed. Its computational performance is evaluated on a larger fluidized bed and shows superior performance over the CPU-based parallelization methods, making DEM calculation no longer the computational bottleneck. Its general applicability to handle complex geometrical domains is further demonstrated by simulations of a gas-solid cyclone separator. This work demonstrates the benefits of a novel coupling approach which enables efficient and robust solutions for industrial applications.
Display omitted
•A novel solid acid nanocatalyst, Ti(SO4)O, was synthesised from TiO2 and chlorosulphonic acid.•The XRD and SAED data confirms the JCPDS-ICDD card № 04-011-4951for Ti(SO4)O.•We ...examined the catalytic activity, stability and reusability of Ti(SO4)O.•The FAME yield from UCO was 97.1% at optimum process conditions using Ti(SO4)O.•Produced biodiesel from UCO satisfied ASTM D6751and EN 14214 standards.
A novel solid acid nano-catalyst Ti(SO4)O was synthesised and used for the simultaneous esterification and transesterification of free fatty acids in used cooking oil (UCO) to produce biodiesel. The synthesised nano-catalyst was fully characterized by different analytical techniques. The XPS results clearly confirmed that the bidentate sulphate coordinated to the Ti4+ metal in the nano-catalyst product. Obtained d-spacing values from the experimental data of XRD peaks and the SAED pattern of produced nano-catalyst agreed well with the d-spacing values from the JCPDS-ICDD card numbers 04-011-4951 for titanium sulphate oxide or titanium oxysulfate crystal structures.This confirms the sulphate groups were within the crystalline structure rather than on the surface of titania nanoparticles, which has not been previously reported. It has been demonstrated 97.1% yield for the fatty acid methyl ester can be achieved usign the synthetised catalyst under a reaction time of 3h, catalyst to UCO ration of 1.5wt% and methanol to UCO ratio of 9:1 at 75°C reaction temperature. The nano-catalyst showed a good catalytic activity for the feedstock containing ≤6wt% free fatty acid. Furthermore, the catalytic activity and re-usability of the Ti(SO4)O for the esterification/transesterification of UCO were investigated. XRD results confirmed that the amount of SO42− species in the solid acid nano-catalyst slowly decreased with re-use after 8 cycles under optimised conditions, which is higher than the reusability of other functionalised titania reported in the literature. Finally, the biodiesel prodcued from this process satisfied the ASTM and European Norm standards.
A review of current techniques for the evaluation of powder mixing Asachi, Maryam; Nourafkan, Ehsan; Hassanpour, Ali
Advanced powder technology : the international journal of the Society of Powder Technology, Japan,
07/2018, Letnik:
29, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Display omitted
•Experimental investigation techniques for powders mixing evaluation are reviewed.•Advantages and drawbacks of all techniques are discussed.•Invasive and non-invasive techniques are ...highlighted.
Blending a mixture of powders to a homogeneous system is a crucial step in many manufacturing processes. To achieve a high quality of the end product, powder mixtures should be made with high content uniformity. For instance, producing uniform tablets depends on the homogeneous dispersion of active pharmaceutical ingredient (API), often in low level quantities, into excipients. To control the uniformity of a powder mixture, the first required step is to estimate the powder content information during blending. There are several powder homogeneity evaluation techniques which differ in accuracy, fundamental basis, cost and operating conditions. In this article, emerging techniques for the analysis of powder content and powder blend uniformity, are explained and compared. The advantages and drawbacks of all the techniques are reviewed to help the readers to select the appropriate equipment for the powder mixing evaluation. In addition, the paper highlights the recent innovative on-line measurement techniques used for the non-invasive evaluation of the mixing performance.
Particle shape driven segregation in particulate mixtures has received limited attention in the literature either experimentally or via simulation. This study investigates the shape driven ...segregation which occurs during the process of heap formation and evaluates the ability of different Discrete Element Method (DEM) simulation approaches to predict the effect. It shows experimentally that the difference in particle shape can drive segregation in a binary mixture and that this segregation can be predicted by DEM models which resolve the particle shape. In this case shape is resolved via a clumped sphere approach. Importantly, the work also demonstrates that simpler models using spherical particles, with rolling friction calibrated to reproduce the experimental angle of repose, tend to underestimate the segregation tendency. The system studied was a binary mixture of irregular shaped particles, a typical spray dried detergent powder and a granulated detergent additive; particle shapes were obtained using X-ray microtomography.
Display omitted
•Segregation of a binary mixture of particles is simulated by Discrete Element Method.•Particle properties and shapes are taken into consideration.•Segregation predicted by DEM is analysed and compared with the experiment.•The results of experiment and DEM closely match when particle shape is considered.•The segregation extent is underestimated when particle shape is approximated by rolling friction.
Assessing the quality of a spread powder layer is critical to understanding powder spreadability in additive manufacturing. However, the small layer thickness presents a great challenge for a ...systematic and consistent characterisation of the spread powder layer. In this study, a novel digital-based characterisation approach is proposed based on space discretization, with an emphasis on the characteristics that is important to powder-bed-based additive manufacturing. With the developed approach, the spread powder layer can be qualitatively illustrated by contour maps and quantified by statistics of packing density, surface profile and pore characteristics. For the first time, two types of pores are proposed for the spread powder layer. The density pore can identify those less populated areas while the chamber pore is able to quantify the size of empty patches observed in the spread powder bed. Applicability of this approach is demonstrated via both simulation-generated and experimentally spread powder layers. Sensitivity tests on the sampling parameters are conducted. This digital-based characterisation method is general and can be applied to both polydisperse and non-spherical particle systems, not only enriching detailed structural analysis of the spread powder layer but also allowing us to quantitatively evaluate powder spreadability in additive manufacturing.
Display omitted
•A general approach to characterise spread powder layer based on space discretization.•Qualitative and quantitative evaluations enabled for packing density, surface profile and pores.•Density pore for less populated area and chamber pore for size of empty patch.•Sensitivity tests conducted on sampling parameters.•Applicability demonstrated for simulation-generated and experimentally spread powder layers.
Identification of the most reliable method to characterise powder flow behaviour in correlation with the conditions of powder spreading in additive manufacturing (AM) is still challenging. In this ...study, a number of standard and advanced flowability techniques were used to characterise the flowability of two grades of Ti6Al4V powder (gas atomized, GA, and hydride-dehydride, HDH) used for the powder bed fusion (PBF) based AM. In parallel, the powder spreading behaviour was characterised using an in-house spreading rig. It is found that GA powder has better spreading behaviour than HDH, owing to its better flowability due to the regular particle shapes. However, none of the flow test techniques investigated in this paper can offer a correlation between the dynamic powder flow and powder spreadability at varying speeds. The study in this work has revealed the shortcomings in correlating the flowability of powder and their spreadability under real process conditions.
Display omitted
•Flowability of two grades of Ti6Al4V powder was characterised using a range of techniques.•The powder spreading behaviour was characterised using an in-house spreading rig.•Caution is needed when correlating powder flow behaviour with the spreadability.•The powder flow behaviour obtained in current study cannot predict the dynamic behaviour of spreading.
Pyrolysis based biorefineries have great potential to convert waste such as plastic and biomass waste into energy and other valuable products, to achieve maximum economic and environmental benefits. ...In this study, the catalytic pyrolysis of different types of plastics wastes (PS, PE, PP, and PET) as single or mixed in different ratios, in the presence of modified natural zeolite (NZ) catalysts, in a small pilot scale pyrolysis reactor was carried out. The NZ was modified by thermal activation (TA-NZ) at 550°C and acid activation (AA-NZ) with HNO3, to enhance its catalytic properties. The catalytic pyrolysis of PS produced a higher liquid oil (70 and 60%) than PP (40 and 54%) and PE (40 and 42%), using TA-NZ and AA-NZ catalysts, respectively. The gas chromatography-mass spectrometry (GC-MS) analysis of oil showed a mixture of aromatics, aliphatic and other hydrocarbon compounds. The TA-NZ and AA-NZ catalysts showed a different effect on the wt% of catalytic pyrolysis products and liquid oil chemical compositions, with AA-NZ showing higher catalytic activity than TA-NZ. FT-IR results showed clear peaks of aromatic compounds in all liquid oil samples with some peaks of alkanes that further confirmed the GC-MS results. The liquid oil has a high heating value (HHV) range of 41.7–44.2 MJ/kg, close to conventional diesel. Therefore, it has the potential to be used as an alternative source of energy and as transportation fuel after refining/blending with conventional fuels.
At moderate stresses, shear cells are the preferred method of powder flow measurement. However, several industrial processes operate at low stresses, where the determination of unconfined yield ...strength by the shear cell technique may be inconsistent, or found not to correlate with observed behaviour. Alternatively, ball indentation can be used, which directly measures hardness; related to unconfined yield strength by the constraint factor. However, it is not known how constraint factor is influenced by particle properties. Here, ball indentation and shear cell methods are applied for glass beads of various size distributions, and the influence of particle size distribution on the constraint factor is explored. The constraint factor is shown to be independent of the pre-consolidation stress, though reduces as the d10, d50 or d90 are increased. Unconfined yield strength inferred from indentation measurements suggest that extrapolation of shear cell data to low stresses overestimates the unconfined yield strength.
Display omitted
•Extrapolating shear cell data from high to low stress overestimates yield strength.•Ball indentation measures hardness; equal to yield strength times constraint factor.•Constraint factor is independent of applied stress.•Constraint factor decreases with increasing particle size and distribution width.•Constraint factor increases with fines content, though reduces with added coarse.
Background
Early detection of Rhodococcus equi pneumonia in foals is essential for horse health and for veterinarians.
Objectives
This study aimed to demonstrate the usefulness of assessing the serum ...concentration of acute‐phase proteins (APPs) in the early diagnosis of pneumonia.
Methods
The study evaluated APPs in 19 Arabian foals with R. equi pneumonia and compared them with 18 normal Arabian foals in equestrian clubs in Tabriz, Iran. Affected foals were identified through history, clinical findings and bacterial culture of tracheal washing. Biochemical methods and polymerase chain reaction tests were performed by examining the 16S rRNA and vapA genes to confirm the diagnosis of bacterial isolates. Blood samples were taken from all sick and healthy horses, and their serum was isolated. APPs in the serum were measured in all the samples.
Results
Rhodococcosis increased the serum concentration of haptoglobin (Hp) and serum amyloid A (SAA) (p < 0.001). The relationship between SAA and Hp was meaningful in the infected group (r = 0.933) but not in the healthy group. In cases where there are clinical findings of R. equi pneumonia, the concentration of SAA and Hp can help the effectiveness of treatment.‐
Conclusions
Serum concentration analysis of APPs can be helpful in early diagnosis and successfully treating foals with R. equi pneumonia.
PDF
