Laboratory-scale Unit Research Articles

Development of a CFD-DEM Model for a 1 MWth Chemical Looping Gasification Pilot Plant Using Biogenic Residues as Feedstock.

Chemical looping gasification (CLG) is a novel dual fluidized bed gasification process that enables the conversion of solid feedstocks to a nitrogen-free syngas through in situ air separation, avoiding a costly air separation unit. While there have been recent advances in experimental studies, modeling of CLG is almost exclusively restricted to lab-scale units or 1D models. In this study, a 3D CFD-DEM model of a 1 MWth fuel reactor for the conversion of solid biomass was developed. Due to the high computational demand of the DEM method, a coarse-grained approach was used in combination with a simplified reaction network. The hydrodynamics were modeled with an EMMS drag model. Simulations were conducted for two woody biomasses and wheat straw based on experimental data of a 1 MWth CLG reactor. The model was able to predict the pressure profile over the reactor accurately, with a mean error below 10%. Carbon conversion and oxygen carrier oxidation were in good agreement with the experimental data with mean deviations below 5%, while reasonable values below 8 mol % mean error were achieved for the gas composition. Discrepancies in the gas composition as well as temperature profile indicate that further work is needed in the pyrolysis step of the model.

Continuous monitoring of residual water content in boiling water-hydrocarbon emulsions during thermomechanical dehydration

Significant waste resources are generated in the form of water-oil emulsions. These emulsions cannot be effectively destroyed on an industrial scale by traditional methods that rely on the settling of the aqueous phase, and therefore, they accumulate in large quantities. Thermomechanical dehydration, based on the evaporation of the water phase, presents a promising process for recycling such waste. However, within the framework of thermomechanical dehydration, the issue of optimizing energy costs for heating raw materials and controlling the water content in the product arises. Standard methods of determining water content under the boiling conditions of highly stable water-hydrocarbon emulsions are characterized by low efficiency, as they require constant sampling and the involvement of additional equipment and personnel. Consequently, this presents a challenge in predicting and creating an automated thermomechanical dehydration process. Therefore, dynamic curves depicting changes in the water content of these emulsions, depending on the temperature of the boiling liquid, have been obtained. It is proposed to determine the rate of temperature increase (dT/dt) of the boiling emulsion for continuous, real-time monitoring of the residual water content and for recording the moment of complete dehydration. Achieving a boiling emulsion temperature of 130 °C–170 °C (or higher) and/or the rate of temperature increase from 3.0 to 5.5 (or above) indicates the complete dehydration of the emulsion. The proposed method can be implemented in any industrial or laboratory-scale unit for thermomechanical dehydration without significant capital costs. It is based on the use of simple devices consisting of temperature sensors and a computing unit for determining the temperature and rate of heating.

Continuous multicolumn ion exchange process for spent lithium-ion battery leachate: Recovery and purification of a Li+Ni+Co mixture

A continuously operated ion exchange process scheme for the recovery and purification of valuable metals from acid leachates of spent Lithium-ion battery cathodes was developed. The aim is to provide a versatile and industrially feasible alternative for liquid–liquid extraction and precipitation for recycling of spent Li-ion batteries. A chelating resin with aminomethylphosphonic acid functional group (Lewatit® MDS TP 260) was used in a laboratory-scale multicolumn configuration that combined counter-current and cross-current operations. The process was operated at 60 °C with a synthetic leachate with pH 1.8 as the feed. A two-step desorption procedure (1.0 M sulfuric acid (H2SO4) followed by 0.4 M potassium oxalate (K2C2O4)) was found to prevent accumulation of strongly bound metals in the resin. 1 M H2SO4 was found sufficient for regeneration. Pure raffinate containing Li, Ni, and Co was successfully separated from impurity metals (Mn, Cu, Al, and Fe). In steady state operation, no loss of ion exchange capacity was observed. The process was optimized experimentally with focus on the effect of fresh feed and eluent flow rates to increase the productivity and improve the recovery rates of the target metals while maintaining a raffinate purity of 100 %. Increasing the amount of leachate processed per switch was found to enhance the recovery of Co, Li and Ni due to the displacement effect. Very high recovery yields (96.97 % for Co, 99.15 % for Ni, and 100 % for Li) were achieved. The laboratory scale unit could process 1.64L(L·h)−1 of leachate to yield 34.04 g(L·h)−1 of Li+Ni+Co mixture in the raffinate. Moreover, Cu+Mn and Al+Fe rich extract streams with 84.74 % and 97.46 % purities were obtained as by-products. With respect to the recovery rates, the continuous ion exchange process is superior to batchwise operation of ion exchange columns, conventional solvent extraction and not to mention precipitation processes making it a viable alternative in hydrometallurgical LIB recycling.

Time-dependent 2-D model for transport of species analysis in electrodialysis: Concentration profiles and fluxes

Electrodialysis (ED) is a separation process that uses an electric field to selectively transport ions through ion exchange membranes. To further advance the technology and bring it to an industrial scale, modeling ED and associated research on transport phenomena have become critical. Nowadays, most of the models present in literature are semi-empirical, which imply a large experimental campaign to properly predict the performance of ED systems. Contrary, a few models are based on Computational Fluid Dynamics to couple the hydrodynamics inside the stack and Nernst-Planck equations to model properly the ED performance. This work aims to provide further understanding of the transport of species in ED focused in the analysis of concentration profiles and fluxes, by building a 2-D computational time-dependent model. Moreover, the analysis of the concentration profiles was conducted at several positions within the stack, revealing that the ion concentration values varied depending on the location. In addition, simulations were contrasted with experimental data from a lab-scale unit. Theoretical data showed a reasonable agreement with experiments, with some discrepancies attributed to the presence of water transport.

Utilizing LPG as an Additive to Enhance the Properties of Iraqi Diesel Oil

For environmental and economic purposes, it is necessary to search for methods that reduce gas emission by flare from the oil refineries. It causes environmental pollution and warmup. All laboratory tests have been completed at Koya University, with the contribution of the Institute of Technology in Koya, to check some readings and verify their accuracy. Increasing the absorptivity of the gases by heavy oil will have expected to improve oil burning characteristics. This research aims to determine the best operating conditions that leads for higher absorption. In this research the diesel oil is considered as a heavy cut and LPG as a light gas. A lab scale unit was installed for that purpose. The amount of changes in oil weight before and after atomizing was determines as well as, the properties of the diesel oil like flash point, cetane number, and diesel index. The effect of a wide range of atomizing time (10, 20, 30, 40, 50, 60, and 90) minutes at different temperatures (0, 10, 20, 30, 40, and 50) °C was considered. The data is discussed and graphically analyzed. The optimum operating conditions is achieved by, 9 liters/minute gas Atomizing flowrate of LPG for one liter of diesel oil, atomizing Temperature is 30 ᵒC, atomizing Time is 30 minutes’ minimum till 60 minutes’ maximum. The produced Diesel Flash Point is 55 ᵒC, and the amount of gas absorption is 24 gm per 850 gm of diesel oil which represent 2.8 % of diesel weight and 5% of LPG gas flowrate.

Ca-looping process using wastes of marble powders and limestones for CO2 capture from real flue gas in the cement industry

The potential of CaO-based sorbents using waste and natural geological materials (two wastes of marble powders and four limestones) for CO2 capture through the Calcium-looping process was assessed using two distinct carbonation gas atmospheres: a real industrial flue gas from a cement plant, and a synthetic gas mixture. The sorbents’ CO2 capture capacity was evaluated on a Fluidized Bed Reactor laboratory scale unit, through ten carbonation-calcination cycles (calcination: 930 °C, 70 % CO2 in air; carbonation: 700 °C, 15 % CO2 in air/real industrial flue gas). The sorbents carbonated with the real industrial flue gas showed a better performance and stability for CO2 capture than with the synthetic gas, which can be explained by presence of moisture in the former. The textural and mineralogical properties of spent sorbents, were characterized by N2 sorption and XRD techniques. The results show that the moisture (below 0.3 %) present in the real flue gas hinders the growth of the CaO crystallite size and leads to an increase of the surface area and total pores volume after 10 cycles. Also, better CO2 capture capacity results were associated with fresh CaO compositions above 52.0 wt. % while for values bellow 46.0 wt. % the performance decreased significantly. The sorbents with high CaO content have an interesting potential to be used in the Ca-looping process under a real carbonation atmosphere, namely the wastes of marble, that appear as a possible economically attractive option, which can contribute to minimize the adverse environmental impacts of the high volume of Portuguese industrial wastes.

Effect of Surfactants on Reverse Osmosis Membrane Performance

The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide (PA) RO membranes were used with nonionic, anionic, or cationic surfactants at a wide range of concentrations. Membrane performance was evaluated using permeate flux and total organic carbon (TOC) rejection. The effects of surfactant type and concentration on RO membranes were assessed. Permeate flux of the PA membrane depended on the surfactant type and concentration. The separation of cationic surfactant aqueous solutions yielded the lowest permeate flux, followed by nonionic and anionic surfactant aqueous solutions, respectively. Surfactant adsorption on the membrane surface occurred at very low concentration of cationic and nonionic surfactants due to electrostatic and hydrophobic interactions, respectively, which affected permeate flux, and micelles did not affect the permeate flux of PA membrane. However, for CA membrane the permeate flux was not affected by the feed solution. Both membranes exhibited satisfactory TOC rejection (92–99%). This study highlights the importance of assessing interactions between membrane material and surfactant molecules to mitigate membrane fouling and guarantee a better performance of the RO membrane.

Long-Term Performance of Ultrafiltration Membranes: Corrosion Fouling Aspect

The past decade has seen a rise in the importance of the ultrafiltration (UF) technique in the separation of various complex solutions. However, the fouling phenomenon is the main limitation to faster process development. To the best of the authors' knowledge, the present paper is the first to aim to identify the role of corrosion fouling in long-term UF. For this purpose, polyvinylidene fluoride (PVDF) and polyethersulfone (PES) membranes were used. The investigations were carried out with the use of both pilot-scale and laboratory-scale units. Results obtained in the present study have clearly demonstrated that the oil concentration has a significant impact on the process performance. Indeed, it has been noted that a reduction in oil concentration from 160 to 100 mg/L resulted in an increase in the PVDF membrane flux from 57 to 77 L/m2h. In addition, it has been shown that the feed temperature has a significant influence on the UF performance. Importantly, it has been shown that corrosion fouling is of vital importance in UF membranes. Indeed, corrosion products such as iron oxides contaminated the membrane surface leading to an irreversible decrease in the UF process performance. In addition, it has been found that repeating the chemical cleaning of the membrane units significantly reduced the intensity of the fouling phenomenon. However, the complete elimination of its effects was not achieved. Therefore, it has been indicated that cleaning agents recommended by membrane manufacturers do not remove corrosion products deposited on the membrane surface. Undoubtedly, the obtained results can be used in the design of UF units leading to the extension of membrane installation lifetime.

Module-level direct coupling in PV-battery power unit under realistic irradiance and load

A photovoltaic (PV) module, battery and consumer or load is usually tied together by a complex power electronics, including maximum power point tracking (MPPT) device for power coupling to maximize output of the PV modules. At the same time, a typical battery itself can play the role of a power coupling element in addition to its main energy storage function. In principle, a properly chosen PV-battery pair can maintain a high degree of internal power coupling even under variable irradiance and load without MPPT electronics. This option is of interest for e.g. module-level integration of PV and battery to cope with natural intermittency of a PV module power output. In this work, we experimentally examine the function of a laboratory scale unit of a 7-cell silicon heterojunction PV module directly connected to a lithium-ion battery and variable load. The unit is the simplest PV-battery module representative for detailed study under a series of emulated realistic profiles of irradiance and power consumption. The directly coupled PV-battery unit shows coupling efficiencies of above 99.8% at high irradiance and approx. 98% on average through the daily cycle – a value that is comparable to modern MPPT devices.

Industrial scale thin-film composite membrane modules for salinity-gradient energy harvesting through pressure retarded osmosis

The current work highlights development of novel thin-film composite hollow fiber membranes for pressure retarded osmosis applications to harvest salinity gradient energy. The membranes were developed with a specific target of harnessing the salinity gradient energy between wastewater reverse osmosis retentate and seawater reverse osmosis brine via osmotic mixing. The hollow fiber membranes were prepared by coating a polyethersulfone substrate with a thin-film composite polyamide layer via interfacial polymerization, which were assembled into modules of different diameters for lab scale and pilot scale evaluation. As the module size increased from 1-in. to 2-in., and 4-in., the water permeability, tested against a 1000 mg/L sodium chloride solution at 15 bar, decreased from 2.6 L m−2 h−1 bar−1 to 2.0 L m−2 h−1 bar−1, and 1.2 L m−2 h−1 bar−1, respectively. The power density, measured in the lab-scale unit using 1 M sodium chloride draw solution, and DI water feed solution, also decreased from 9.1 W/m2 to 5.3 W/m2 with increasing module size. Pilot scale evaluation of the 4-and 8-in. modules on a 24 m3/day unit resulted in lower power densities of 2.5 W/m2 and 1.5 W/m2 which translated to 0.024 kWh/m3 and 0.05 kWh/m3 of salinity-gradient energy harvested, respectively.

Modelling of Red-Mud Particle-Solid Distribution in the Feeder Cup of a Thickener Using the Combined CFD-DPM Approach

The paper evaluates the behavior of a red-mud solid fraction in a thickener feeder cup, aiming to identify the main characteristics of particle distribution in the flocculation zone and to determine the dependencies affecting the further process taking place in the particle-free sedimentation zone in the thickener-thickening unit. This work used mathematical and numerical modeling to study the influence of such parameters as the flow rate of the feed pulp in the thickener, the flow rate of the flocculant, the density of pulp at the inlet to the unit, and the viscosity and temperature of the pulp on the particle-size distribution from under the feeder cup. The results and dependencies obtained are intended to be used as nominal values in the red-mud thickening process performed on a lab-scale unit.

Upgrading of crude oil desalting unit of Baiji oil refinery

The desalting and dehydration system in Baiji oil refinery uses a combination of methods including electrical, thermal, chemical, and physical methods. The salt content is within the range of 14–20 mg/L. The desalting efficiency rarely exceeds 75%, thus salt and water content exceed the Iraqi permissible limit. The purpose of the present work is to improve the performance of the Baiji oil refinery desalting unit without any major alteration of the field unit configuration. A laboratory scale unit is designed and constructed to investigate the desalting unit performance under various operating conditions. The results showed that under optimum operating parameters, the obtained desalting and dehydration efficiencies are 98.1% and 97.6%, respectively. The corresponding salt concentration and water content are 0.268 mg/L and 0.1 vol.%, respectively, which were within the acceptable Iraqi levels.

Scaling up a woodchip-fired containerized CHP ORC unit toward commercialization

Microcogeneration utilizing organic Rankine cycle technology has seen challenges in commercialization, despite its vast application potential. The market is large, but so is the competition from standard boilers. This was also the case for a previously developed biomass-fired 50 kWth 2 kWe unit intended for large buildings and small industries. Therefore, a scaled-up 120 kWth and 6.2 kWe unit has been proposed with better commercialization prospects.This paper discusses the process of scaling up, designing, assembling and operation of this system. It includes innovative modifications of previously applied technologies regarding the boiler, expander and the overall system configuration. Both units utilize a rotary vane expander as a specific feature of the design. A comparison with the previous smaller unit is performed on several thousand hours of experimental data. The larger unit reaches higher net combined heat and power production efficiency, reaching 89.3%, even though the expander nominal isentropic efficiency slightly drops to 56%. Economic considerations and market feasibility are discussed with respect to the scaling-up from the laboratory scale unit towards commercialization. Thanks to the simplification of the unit, regardless of the scale-up, the absolute cost remains nearly the same for both units.

Применение наночастиц для производства пара под действием солнечного излучения

Nanoparticles suspended in the base fluid intensify the light-absorbing properties of the medium within wavelength range from 0,2 to 2,5 μm significantly. Also, they can serve as vapor bubble nucleation sites when the base fluid is boiling. Such suspensions are widely used to design the direct absorption solar collectors, in which the nanofluid is possessed both the working fluid and solar energy absorber. However, there is a lack of theoretical models that are capable to evaluate the steam rated capacity of direct absorption solar collector. Thus, the aim of the present paper is an experimental and theoretical study of the boiling of nanofluid exposed to thermal radiation. The experimental study has been carried out on a laboratory-scale unit with a solar radiation simulator. The experimental unit is capable to operate at a continuous steady-state mode with recirculation of condensed fluid. Two types of nanoparticles have been tested: multiwall carbon nanotubes with two sizes of 49 nm and 72 nm and 110 nm iron oxide particles Fe3O4. Distilled and salt water has been used as the base fluid for all types of particles. Mass fraction of particles is varied from 0,5 to 5 %. The reference experiment has been carried out for salt water in a blackened receiver. The theoretical model assumes that boiling is localized in a narrow region adjacent to the irradiated surface. An experimental study of the steam rated capacity for various types of particles has been carried out. An analytical expression has been proposed to estimate the steam rated capacity during the boiling of a nanofluid exposed to thermal radiation. Comparison of the experimental data for the distilled water-based and saltwater-based nanofluids has been carried out. It is found that the addition of sea salt does not affect the steam generation significantly. The maximum difference is 12 %. The highest steam rated capacity is achieved when using carbon nanotubes of mass fraction of 5 %. The steam rated capacity is increased by 23 % compared with the reference experiment. The theoretical model reproduces the experimental data with an average deviation of 7 %. Application of nanoparticles in direct absorption solar collectors allows us to increase the steam rated capacity compared with the boiling of the base liquid in a blackened receiver. The theoretical model is capable to estimate to a high precision the steam rated capacity in case of boiling of suspension exposed to thermal radiation. The results of this study may be of interest during the development of solar power plants with a steam turbine cycle.

LABORATORY STUDY OF ELECTROCOAGULATION FOR COD REMOVAL FROM WASTEWATER

The current work investigates the ability of the new aluminium-based electrocoagulation (EC) cell to remediate chemical oxygen demand (COD) from synthetic wastewater. The experimental work was carried out using a rectangular EC cell (10 cm in length, 9.5 cm in width, and 7 cm in depth). The EC cell was supplied with six perforated aluminium electrodes; four of these electrodes were used in the treatment methods (connected to DC electrical current), while the first and the last electrodes were used as baffle plates (to mix water). This lab-scale unit was used to treat synthetic wastewater having 300 mg/l of COD, considering the effect of the treatment time and initial pH. After 40 minutes of treatment at a pH of 7 and a current density of 10 A/m2, 51% of COD was removed by the new EC unit. The results also revealed that the removal of the COD is positively influenced by the increase of the applied current density and/or treatment time.

Enhanced production from an Air Gap Membrane Distillation Desalination system by varying the feed entry angle

The membrane distillation (MD) process is an evaporative metho driven by the partial pressure difference between two different temperature solutions, namely the hot feed and the coolant. The hot feed evaporates, and the vapour gets condensed to the cooler side. A hydrophobic membrane maintains the evaporating surface. Air Gap Membrane Distillation(AGMD) separates the hot feed from the coolant by a narrow air gap and a coolant plate. The condensate forms on the coolant plate, and the air gap works as an insulation for the heat loss through the membrane. The salient parameters like feed temperature, coolant temperature, and air gap thickness have already been identified through research in previous years. In this study, an innovative technique has been tested to minimize the polarization and increase the production from an AGMD lab-scale unit. The effect of the feed flow entry angle has been investigated. Also, the combined effect of inclined flow entry and a finned coolant surface has been studied. It has been found from the experiments that with a feed flow entry angle of 60°, the system shows an average of 10% to 14% boost in performance. When 60° inlet flow angle and finned coolant plate work in combination, an average of 69% to 78% increase of distillate flux was observed with the same energy input.

Ultrasound-Assisted Cold Pasteurization in Liquid or SC-CO2

Various types of chemical and physical protocols are used, thermal treatment in particular, to increase the quality of bulk food products (for example, dates or some sort of nuts) and extend shelf life, and combinations of methods are frequently used to achieve the best results. However, the use of these processing methods is not always the best option to preserve the initial taste and appearance of food products. For instance, a product may lose its initial natural appearance and acquire different flavors due to chemical transformations that occur at certain temperatures or when the products are treated with chemicals. Non-thermal treatment methods are called “cold” pasteurization. This is a set of advanced techniques that are based on physical and chemical effects that do not result in the structural food-product transformations caused by heating. We have developed and tested a new technique for efficient food-product processing and cold pasteurization in an ultrasonic field under pressure in an atmosphere of supercritical or subcritical carbon dioxide. A laboratory-scale unit that was designed and built for this purpose has experimentally proven the feasibility of this process and demonstrated high efficiency in suppressing pathogenic flora.

Optimized Production of Syngas from Rice Hush Using Steam Explosion in Dual Fluidized Bed Gasifier

Converting rice husk into energy is a promising method of generating renewable energy and reducing greenhouse gas emissions. In this research rice hush is considered as biomass fuel. The characteristics of rice husk gasification were investigated at an Equivalence Ratio (ER) of 0.25–0.38 and a gasifier temperature of 750-870°C in 20 tons per day (TPD) using steam explosion process in fluidized bed gasifier system. Different operation conditions, temperatures and loads, are investigated for their effects on the compositions, calorific properties, gasification efficiencies of syngas. The effects of the critical parameters, namely, Steam-to-Biomass Ratio (S/B), Particle size variation and gasification temperature on the quality of the product gas as well as the gasifier cold gas efficiency were analyzed. This is the new finding in the research. The optimal conditions of the gasification operation were an ER of 0.20 and gasifier temperature of 800°C. The low heating value of the gas product and cold gas efficiency were 1390kcal/Nm³ and 75%, respectively. After passing the generated gas through the gas cleaning units, it was confirmed that the tar in the product gas was removed with an efficiency of 98%. The cleaned product gas was used for the operation of 420kW, gas engine. Pressure loss often occurred at the bottom of the gasifier during the gasification operation; we found that the agglomerates generated by the gasification process caused it. To prevent the pressure loss caused by the agglomerates, the stable control of temperature inside the gasifier is needed and an ash removal device remove agglomerates should be installed to maintain stable long-term operation. This paper leads towards the production of Syngas and further on the electricity from the rice husk, an eminent biomass, copiously available all around the world. Especially in Pakistan, the rice is used abundantly so the raw material is easily available. The gas is produced using the gasification process in dual fluidized gasifier. It is a wonderful alternative to the natural gas with high calorific value. The sulfur contents are quite less compared to natural gas. It also have a good correlation with environment as flue gases emission is negligible relative to other source like coal, wood, plastic, waste etc. Another benefit of this process is the waste management and pollution control. The results are developed by using the detailed analysis of the process values of plants which is generating electricity by rice husk gasification. We learned, all results revealed that the dual fluidized bed gasification is more economical and efficient method compared to all other methods for commercial scale production of syngas. Results are analyzed which imply that the biomass is more gigantic source which replace the fossil fuels and leads towards the green energy in a more economical way. This paper provides an overview of previous works on combustion and gasification of rice husk in atmospheric fluiuidized bed reactors and summarizes the state of the art knowledge. As the high ash content, low bulk density, p characteristics and low ash melting point makes the other types of reactors like grate furnaces and downdraft gasifers either inefficient or unsuitable for rice husk conversion to energy, the fluiuidized bed reactor seems to be the promising choice. The overview shows that the reported results are from only small bench or lab scale units. Although a combustion efficiency of about 80% can normally be attained; the reported values in the literature, which are more than 95%, seem to be in higher order. Combustion intensity of about 530kg/h/m² is reported. It is also technically feasible to gasify rice husk in a fluidized bed reactor to yield combustible producer gas, even with sufficient heating value for application in internal combustion engines.

Micro Freeze-Dryer and Infrared-Based PAT: Novel Tools for Primary Drying Design Space Determination of Freeze-Drying Processes

PurposePresent (i) an infrared (IR)-based Process Analytical Technology (PAT) installed in a lab-scale freeze-dryer and (ii) a micro freeze-dryer (MicroFD®) as effective tools for freeze-drying design space calculation of the primary drying stage.MethodsThe case studies investigated are the freeze-drying of a crystalline (5% mannitol) and of an amorphous (5% sucrose) solution processed in 6R vials. The heat (Kv) and the mass (Rp) transfer coefficients were estimated: tests at 8, 13 and 26 Pa were carried out to assess the chamber pressure effect on Kv. The design space of the primary drying stage was calculated using these parameters and a well-established model-based approach. The results obtained using the proposed tools were compared to the ones in case Kv and Rp were estimated in a lab-scale unit through gravimetric tests and a thermocouple-based method, respectively.ResultsThe IR-based method allows a non-gravimetric estimation of the Kv values while with the micro freeze-dryer gravimetric tests require a very small number of vials. In both cases, the obtained values of Kv and Rp, as well as the resulting design spaces, were all in very good agreement with those obtained in a lab-scale unit through the gravimetric tests (Kv) and the thermocouple-based method (Rp).ConclusionsThe proposed tools can be effectively used for design space calculation in substitution of other well-spread methods. Their advantages are mainly the less laborious Kv estimation process and, as far as the MicroFD® is concerned, the possibility of saving time and formulation material when evaluating Rp.

Coarse-Grain DEM Modelling in Fluidized Bed Simulation: A Review

In the last decade, a few of the early attempts to bring CFD-DEM of fluidized beds beyond the limits of small, lab-scale units to larger scale systems have become popular. The simulation capabilities of the Discrete Element Method in multiphase flow and fluidized beds have largely benefitted by the improvements offered by coarse graining approaches. In fact, the number of real particles that can be simulated increases to the point that pilot-scale and some industrially relevant systems become approachable. Methodologically, coarse graining procedures have been introduced by various groups, resting on different physical backgrounds. The present review collects the most relevant contributions, critically proposing them within a unique, consistent framework for the derivations and nomenclature. Scaling for the contact forces, with the linear and Hertz-based approaches, for the hydrodynamic and cohesive forces is illustrated and discussed. The orders of magnitude computational savings are quantified as a function of the coarse graining degree. An overview of the recent applications in bubbling, spouted beds and circulating fluidized bed reactors is presented. Finally, new scaling, recent extensions and promising future directions are discussed in perspective. In addition to providing a compact compendium of the essential aspects, the review aims at stimulating further efforts in this promising field.