Potential For Intensification Research Articles

Review on Additive Manufacturing of Catalysts and Sorbents and the Potential for Process Intensification

Additive manufacturing of catalyst and sorbent materials promises to unlock large design freedom in the structuring of these materials, and could be used to locally tune porosity, shape and resulting parameters throughout the reactor along both the axial and transverse coordinates. This contrasts catalyst structuring by conventional methods, which yields either very dense randomly packed beds or very open cellular structures. Different 3D-printing processes for catalytic and sorbent materials exist, and the selection of an appropriate process, taking into account compatible materials, porosity and resolution, may indeed enable unbounded options for geometries. In this review, recent efforts in the field of 3D-printing of catalyst and sorbent materials are discussed. It will be argued that these efforts, whilst promising, do not yet exploit the full potential of the technology, since most studies considered small structures that are very similar to structures that can be produced through conventional methods. In addition, these studies are mostly motivated by chemical and material considerations within the printing process, without explicitly striving for process intensification. To enable value-added application of 3D-printing in the chemical process industries, three crucial requirements for increased process intensification potential will be set out: i) the production of mechanically stable structures without binders; ii) the introduction of local variations throughout the structure; and iii) the use of multiple materials within one printed structure.

Recent Advances in the Development of Highly Conductive Structured Supports for the Intensification of Non-adiabatic Gas-Solid Catalytic Processes: The Methane Steam Reforming Case Study

Structured catalysts are strong candidates for the intensification of non-adiabatic gas-solid catalytic processes thanks to their superior heat and mass transfer properties combined with low pressure drops. In the past two decades, different types of substrates have been proposed, including honeycomb monoliths, open-cell foams and, more recently, periodic open cellular structures produced by additive manufacturing methods. Among others, thermally conductive metallic cellular substrates have been extensively tested in heat-transfer limited exo- or endo-thermic processes in tubular reactors, demonstrating significant potential for process intensification. The catalytic activation of these geometries is critical: on one hand, these structures can be washcoated with a thin layer of catalytic active phase, but the resulting catalyst inventory is limited. More recently, an alternative approach has been proposed, which relies on packing the cavities of the metallic matrix with catalyst pellets. In this paper, an up-to-date overview of the aforementioned topics will be provided. After a brief introduction concerning the concept of structured catalysts based on highly conductive supports, specific attention will be devoted to the most recent advances in their manufacturing and in their catalytic activation. Finally, the application to the methane steam reforming process will be presented as a relevant case study of process intensification. The results from a comparison of three different reactor layouts (i.e. conventional packed bed, washcoated copper foams and packed copper foams) will highlight the benefits for the overall reformer performance resulting from the adoption of highly conductive structured internals.

Phase change materials based on nanoparticles for enhancing the performance of solar photovoltaic panels: A review

Phase change materials (PCMs) are one of the promising materials in thermal energy storage (TES) systems, while commonly utilized PCMs have weak thermal conductivity. Therefore, elevating high relatively thermally conductivity for the PCM composites using various nanoparticles with different named the nano-enhanced phase change material (NePCM) is an encouraging solution for regulating the PV temperatures and hence prolonging the lifetime of the utilized photovoltaics. The present paper introduces the cooling methods of PV panels as well as reviews the PV/PCM systems. Additionally, the cooling of photovoltaics based on the NePCM methods are studied showing the preparing methods of the NePCM nanocomposites. The results indicated the dispersion of NPs into the PCMs modifies the thermo-physical properties of PCM like melting temperature, supercooling degree, heat of fusion, viscosity, etc., as well as the mass fraction of NPs affects remarkably the enhanced thermal conductivity (TC) of NePCM nanocomposites. Thus, the NePCMs introduce superior characteristics of heat transfer as a result of intensifying the TC of PCM. Therefore, adding the nanoparticles to the PCM had a noteworthy potential for intensification the thermos-physical properties of PCM so it is a promising choice for TES in solar photovoltaics applications.

CO2 absorption with diamine functionalized deep eutectic solvents in microstructured reactors

Deep eutectic solvents (DESs) have gained much attention to capture CO2 nowadays because of their simpler synthesis, higher sustainability and better eco-friendly properties compared to ionic liquids and conventional amine sorbents. Herein, we analyzed the CO2 absorption performance of five novel diamine functionalized DESs in microstructured reactors (MSRs) with metal foams as packing materials. Interestingly, the DES functionalized with N-methyl-1,3-propanediamaine (MAPA) showed remarkable absorption performance without significant viscosity rise. The CO2 loading and absorption efficiency of this DES could reach 0.78 mol of CO2 / mol of diamine and 98% at the gas to liquid flow rate ratios of 640 and 240, respectively. Even computational studies showed that the ethylenediamine (EDA) functionalized DES had the highest CO2 uptake ability due to the low energy barrier, but sudden rise in viscosity of the EDA functionalized DES reduced its CO2 absorption ability compared to the MAPA functionalized DES. Further experiments indicated that the MAPA functionalized DES showed low heat of absorption and remarkable regeneration ability. Overall rate constant and absorption flux of this DES were higher than most previously used amine functionalized DESs. Consequently, the unification of this remarkable DES and microreactors has great process intensification potential for CO2 absorption.

Demonstration of applied linear model predictive control for an enzymatic reactive dividing wall column

The synergistic integration of different processing steps in multifunctional units offers huge potential for bioprocess intensification. Especially reactive separation technologies have been widely applied in chemical processes, with reactive distillation being termed the front-runner of industrial process intensification. The concept can be transferred to bioprocesses in terms of enzymatic reactive distillation, which can further be intensified through thermal coupling with a subsequent distillation column into an enzymatic reactive dividing wall column. While such a highly integrated process offers considerable potential for operational and investment cost savings, it also faces operational challenges and limitations caused by the strong degree of integration and the temperature sensitivity of the biocatalyst, that need to be addressed by a sophisticated process control system. The current study demonstrates the applicability and efficiency of a linear model predictive control approach for the enzymatic reactive dividing wall column in a pilot plant application. The transesterification of butanol and hexyl acetate to hexanol and butyl acetate, catalyzed by the enzyme CalB (Novozym 435), serves as a model reaction. The control performance is illustrated for a setpoint adjustment and a feed disturbance, for which a comparative evaluation with an established PI-control approach is conducted.

Additive manufacturing of composite porosity mixer electrodes

Electrochemical reactors present a viable means to unleash the full potential of renewable energies. With maximized surface areas, and thus increased reaction rates, the elimination of diffusion boundary layers on the electrode surface becomes increasingly important, calling for 3D structured electrodes that provide mass transport control inside the reactor. We produce 3D structured stainless steel mixer electrodes with high surface areas from selective laser sintering. By global control of the laser power, electrodes are rendered intrinsically porous without the need to define micro-features. The result is a composite porosity electrode (CPE) with a highly porous skin, a rigid porous support and a dense current collector core. The CPE shows increasing reaction rate of the porous surface with intensifying passive mixing at rising Reynolds numbers. This is explained by a large electrochemical surface area of the porous electrode that is made accessible through the mixer electrode’s mass transport enhancement. With its excellent scalability, this method promises great potential for the process intensification of a wide range of electrochemical applications.

A classification of cultivated pastures in the Brazilian Cerrado for sustainable intensification and savanna restoration.

The Brazilian Cerrado, with over 200 million hectares, has approximately 28% of its area occupied by cultivated pasturelands and 39% of them are degraded. In this study, we propose a new classification of the Cerrado pastures and recommendations for sustainable intensification and savanna restoration. We propose seven classes of pastures based on the ground cover proportions of exotic grass, bare soil, and native vegetation. These lands need to be acknowledged for their biodiversity conservation and potential for sustainable intensification and restoration. In order to make ecological intensification available for the ranchers, research and technology transfer have to embrace native tree species-based silviculture, native-grass-based forage management and enhancement, and value chain of biodiversity-friendly products. The pasture management proposals of this paper are based on a concept of biodiversity as an ecosystem service, promoting local productivity and global ecosystem services.

The influence of fluid dynamics on the selectivity of fast gas–liquid reactions in methanol

One important strategy for process intensification is the enhancement of yield and selectivity in fast gas–liquid reactions, like oxidations, hydrogenations or halogenations. However, the interplay between fluid dynamics and competitive chemical reactions has not yet been understood to an extent that allows tailoring the flow and concentration fields for intensified reactions. To understand the interplay, the fluid dynamic conditions surrounding Taylor bubbles rising in an organic solvent are studied and compared to data of aqueous systems from the literature. The local flow fields are measured using Particle Image Velocimetry (PIV) and compared to spectroscopically derived selectivity data of a competitive consecutive gas–liquid reaction. The general rising behavior of Taylor bubbles in methanol is confirmed to be similar to those of bubbles in aqueous systems. However, as surface active agents do not affect the interface mobility in organic solvents, the local flow structures in the bubble wake differ significantly from those of bubbles rising in water, impacting the mixing behavior. Finally, the flow fields are compared to the concentration fields of the main and side products. Thereby, a decisive influence of the fluid dynamics on yield and selectivity becomes apparent, unveiling the potential for process intensification.

Building resilient agricultural system through groundwater management interventions in degraded landscapes of Bundelkhand region, Central India

Study regionThe study was carried out at community scale watershed in one of the fragile ecologies of Central India. Study focusThis paper quantifies the impact of rainwater management (RWM) interventions on major water balance components, irrigation use, crop intensification and energy consumption and their interrelationships. New hydrological insights for the regionRWM interventions harvested additional 35 mm of surface runoff in various masonry structures and facilitated groundwater recharge from 720 mm rainfall received. The net groundwater recharge during monsoon season was estimated 75−80 mm; out of this, 25 % (15−20 mm) was used in kharif and 75 % (50−60 mm) in rabi season. Groundwater recharge largely took place in wet and normal years due to RWM interventions, which supported for meeting freshwater demand in recurring dry years. Increased groundwater recharge helped to enhance cropping intensity from 120 % to 180 % by converting significant fallow lands into productive cultivation. The time required to refill dug wells decreased by 50 % with every one meter increment in hydraulic head. Therefore, well recovery period reduced minimum by 50 % after the project interventions. The study shows a huge untapped potential for sustainable crop intensification by adopting science-based natural resource management approach in fragile eco regions of the semi-arid tropics.

Detailed investigation of liquid distribution and holdup in periodic open cellular structures using computed tomography

Periodic open cellular structures (POCS) show great potential for process intensification in catalytic reactors due to their favorable properties regarding heat transfer, pressure drop and liquid distribution. In multiphase applications, POCS can be employed as multifunctional catalyst carrier with integrated liquid distribution function for enhancing the performance of heterogeneously catalyzed reactions. This applies particularly to trickle bed reactors where a uniform liquid distribution is of great importance. In this contribution, the liquid distribution of three POCS of different unit cell geometry is investigated using a custom-made computed tomography scanner with high spatial resolution. POCS with the Kelvin, diamond and DiaKel unit cell, respectively, were manufactured via fused deposition modeling out of acrylonitrile butadiene styrene. The liquid distribution was examined in dependence of the unit cell as well as for different liquid and gas flow rates. The three POCS show different behavior for the liquid distribution and holdup within the structures. POCS with Kelvin and DiaKel unit cell geometry show a higher liquid holdup as well as a more uniform liquid distribution compared to diamond unit cell POCS. Also, the liquid filling between the individual POCS that are stacked in the column is dependent on the unit cell.

Process intensification of the ionoSolv pretreatment: effects of biomass loading, particle size and scale-up from 10\xa0mL to 1\xa0L

The ionoSolv process is one of the most promising technologies for biomass pretreatment in a biorefinery context. In order to evaluate the transition of the ionoSolv pretreatment of biomass from bench-scale experiments to commercial scale, there is a need to get better insight in process intensification. In this work, the effects of biomass loading, particle size, pulp washing protocols and 100-fold scale up for the pretreatment of the grassy biomass Miscanthus giganteus with the IL triethylammonium hydrogen sulfate, [TEA][HSO4], are presented as a necessary step in that direction. At the bench scale, increasing biomass loading from 10 to 50 wt% reduced glucose yields from 68 to 23% due to re-precipitation of lignin onto the pulp surface. Omitting the pulp air-drying step maintained saccharification yields at 66% at 50 wt% loading due to reduced fiber hornification. 100-fold scale-up (from 10 mL to 1 L) improved the efficacy of ionoSolv pretreatment and increasing loadings from 10 to 20 wt% reduced lignin reprecipitation and led to higher glucose yields due to the improved heat and mass transfer caused by efficient slurry mixing in the reactor. Pretreatment of particle sizes of 1–3 mm was more effective than fine powders (0.18–0.85 mm) giving higher glucose yields due to reduced surface area available for lignin re-precipitation while reducing grinding energy needs. Stirred ionoSolv pretreatment showed great potential for industrialization and further process intensification after optimization of the pretreatment conditions (temperature, residence time, stirring speed), particle size and biomass loading. Pulp washing protocols need further improvement to reduce the incidence of lignin precipitation and the water requirements of lignin washing.

How sustainable is sustainable intensification? Assessing yield gaps at field and farm level across the globe

Sustainable intensification has been proposed as a pathway to achieve food security and reduce environmental impacts of agriculture by focusing on narrowing yield gaps on existing agricultural land while improving resource use efficiencies. There is a general consensus that regions with large yield gaps can benefit most from sustainable intensification but it remains unclear how sustainable this is for farmers given their current resource constraints and livelihood strategies. Here, we draw upon three contrasting case studies, for which detailed data at field and farm levels were available for yield gap decomposition, to assess how sustainable intensification of crops (at field level) works out at farm level using environmental and socio-economic indicators. Although there is large potential for future intensification (more output with more input) of cereal production in southern Ethiopia, current input use in these farming systems is not economically and environmentally sustainable at farm level. The same is true for rice production in Central Luzon where sustainable intensification (more output with less input) can help to narrow yield gaps and improve N use efficiency (NUE) but it is not profitable due to the heavy reliance on costly hired labour. Trade-offs between yield gap closure and labour productivity were also observed in the aforementioned farming systems. Arable farms in the Netherlands exhibit small yield gaps as well as higher economic performance, NUE and N surplus compared to those observed in Southern Ethiopia and Central Luzon. For improving environmental sustainability, these farms require increases in resource-use efficiency and a reduction of the environmental impacts through a lower use of inputs (same output with less input). We conclude that public investments conducive for innovation and profitable farming are essential to make technologies accessible and affordable for farmers and to ensure that yield gaps can be narrowed and sustainability objectives served at the farm level.

A Logistic-growth-equation-based Intensity Prediction Scheme for Western North Pacific Tropical Cyclones

Accurate prediction of tropical cyclone (TC) intensity remains challenging due to complex physical processes involved in TC intensity changes. A 7-day TC intensity prediction scheme based on the logistic growth equation (LGE) for the western North Pacific (WNP) has been developed using the observed and reanalysis data. In the LGE, TC intensity change is determined by a growth term and a decaying term. These two terms comprise four free parameters, including the time-dependent growth rate and maximum potential intensity (MPI), and two constants. With 33 years of training samples, optimal predictors are selected first, and then the two constants are determined based on the least square method, making the regressed growth rate from the optimal predictors as close to the observed as possible. The growth rate is further estimated based on a step-wise regression (SWR) method and a machine learning (ML) method for the period 19822014. Using the LGE-based scheme, a total of 80 TCs during 20152017 are used to make independent forecasts. Results show that the root mean square errors of the LGE-based scheme are much smaller than those of the official intensity forecasts from the China Meteorological Administration (CMA), especially for TCs in the coastal regions of East Asia. Moreover, the scheme based on the ML shows better forecast skills than that based on the SWR. The new prediction scheme also exhibits strong potential for rapid intensification and weakening forecasts and an extension of the CMA current 5-day forecasts to 7-day forecasts.

Mass transfer and kinetic characteristics for CO2 absorption in microstructured reactors using an aqueous mixed amine

Microreactors are frequently used for the process intensification of CO2 absorption, but most CO2 absorption studies in microreactors are restricted to a low flow rate ratio of feed gas to absorbent because of insufficient CO2 loading of conventional amines. Herein, we investigated mass transfer and kinetic characteristics of CO2 absorption using an aqueous mixed amine absorbent composed of 25 wt.% N-methyldiethanolamine (MDEA) and 5 wt.% hexamethylenediamine (HMDA) at the gas to liquid flow rate ratio range from 88.9 to 666.7 in four microstructured reactors with metal foams as packing materials in the packed-bed section. The CO2 loading of this amine absorbent reached 0.32 mol of CO2 per mol of MDEA at the gas to liquid flow rate ratio of 400, which is significantly higher than the conventional amines. Regeneration efficiency of this mixed amine absorbent was remarkable in three successive regenerated cycles at the gas to liquid flow rate ratios of 181.8 and 222.2. The second-order rate constants of HMDA were higher than the conventional amines, reflecting its high ability to reduce energy barrier and accelerate the CO2 absorption rate. The overall volumetric mass transfer coefficient and absorption efficiency were raised to 13.5 s−1 and 97% at the gas to liquid flow rate ratios of 153.8 and 88.9, which are obviously higher than those reported for other microreactors. Optimization of overall reaction rate constant and mass transfer coefficient was executed through multi-objective optimization using genetic algorithm and validated through experimentation. Finally, the comparison of the mass transfer characteristics among various microreactors indicated that the strategy of combining this remarkable mixed amine absorbent with microstructured reactors with metal foams packing has strong process intensification potential for CO2 absorption at high gas to liquid flow rate ratios.

The Intensity-dependence of Tropical Cyclone Intensification Rate in a Simplified Energetically Based Dynamical System Model

AbstractIn this study, a simple energetically based dynamical system model of tropical cyclone (TC) intensification is modified to account for the observed dependence of the intensification rate (IR) on the storm intensity. According to the modified dynamical system model, the TC IR is controlled by the intensification potential (IP) and the weakening rate due to surface friction beneath the eyewall. The IP is determined primarily by the rate of change in the potential energy available for a TC to develop, which is a function of the thermodynamic conditions of the atmosphere and the underlying ocean, and the dynamical efficiency of the TC system. The latter depends strongly on the degree of convective organization within the eyewall and the inner-core inertial stability of the storm. At a relatively low TC intensity, the IP of the intensifying storm is larger than the frictional weakening rate, leading to an increase in the TC IR with TC intensity in this stage. As the storm reaches an intermediate intensity of 30-40 m s-1, the difference between IP and frictional weakening rate reaches its maximum, concurrent with the maximum IR. Later on, the IR decreases as the TC intensifies further because the frictional dissipation increases with TC intensity at a faster rate than the IP. Finally, the storm approaches its maximum potential intensity (MPI) and the IR becomes zero. The modified dynamical system model is validated with results from idealized simulations with an axisymmetric nonhydrostatic, cloud-resolving model.

Micromixing in a gas–liquid vortex reactor

AbstractThe gas–liquid vortex reactor (GLVR) has substantial process intensification potential for multiphase processes. Essential in this respect is the micromixing efficiency, which is of great importance in fast reaction systems such as crystallization, polymerization, and synthesis of nanomaterials. By creating a vortex flow and taking advantage of the centrifugal force field, the liquid micromixing process can be intensified in the GLVR. Results show that introducing a liquid into a gas‐only vortex unit results in suppression of primary and secondary gas flow. The Villermaux–Dushman protocol is applied to study the effects of the gas flow rate, liquid flow rate, and liquid viscosity based on a segregation index. Based on the incorporation model and reaction kinetics, the micromixing time of the GLVR is determined to be in the range of 10−4 ~ 10−3 s, which is comparable to the highly efficient rotating packed bed and substantially better than a static mixer.

Estimating biological capacity for grass-finished ruminant meat production in New England and New York

The Northeastern United States contributes a small share to national meat production. However, increasing interest in local food production and on-going challenges posed by drought and fire on Western rangelands give reason to believe that the importance of Northeastern grass-based ruminant meat could grow in the near future. Using an integrated modeling approach, the present study quantifies current and potential biological capacity for grass-based ruminant meat production in New York and New England. We used the Cropland Data Layer (CDL) to establish the area and spatial distribution of hay and pasture, with area estimates validated against the USDA Census of Agriculture. Potential forage productivity was modeled using ordinary least squares linear regression of SSURGO non-irrigated crop yield values for pasture against NICC classes and subclasses, drainage classes, slope, air temperature, and quintiles of depth to restrictive soil layers, using ordinary least squares linear regression. Forage yield gaps were calculated by comparing potential productivity to annual crop survey data from the USDA. The potential production of grass-finished cattle based on either current or potential forage yields based on models of feed needs for spring- and fall-calving herds produced using the Large Ruminant Nutritional System. We show that more than half of agricultural land cover currently appears to be pasture, but that only some of this land is actively used for grazing, with actual yields just 54% or 47% of economic yields for hay and pasture respectively. Overall, we estimate the potential to increase the regional beef herd size by 90% to 270% by increasing yields, expanding production into unutilized grassland area, or both. We conclude that up to 3% of U.S. beef could be produced in the region, on less than 0.5% of U.S. agricultural land area, pointing to high potential for sustainable intensification of beef production in the Northeastern United States. Realizing this potential, however, requires closing of yield gaps and intensification of the use of land in agricultural cover. The amount of biophysical productivity that is economically attainable remains highly uncertain.

Key Environmental Factors for Rapid Intensification of the South China Sea Tropical Cyclones

Forecasting rapid intensification (RI) of the South China Sea (SCS) tropical cyclones (TCs) remains an operational challenge, mainly owing to the incomplete understanding of its physical mechanisms. Based on TC best-track data, atmospheric analysis data, and sea surface temperature data, this study compares temporal evolution characteristics of environmental conditions from the previous 24 h to the onset time for RI and non-RI TCs in the SCS during 2000–2018, and then identifies key factors for RI of the SCS TCs using the box difference index and stepwise regression. A combination of strong divergence in the upper troposphere and strong convergence in the boundary layer, weak deep-layer vertical wind shear, fast storm translation speed, and high TC intensification potential (i.e., maximum potential intensity minus current intensity) north of the storm center at the previous 24 h are favorable for RI of the SCS TCs, and their importance for RI is in descending order. The results may shed light on operational forecasting of rapid intensification of the SCS TCs.

“A Good Deal of Intensity”: On the Development of Degree and Quantity Modifier Good

This paper explores how the originally descriptive adjective good (e.g., “a good man”) developed degree modifier (e.g., “a good scolding”) and quantity modifier (e.g., “a good many people”) uses. The work is innovative in exploring the intensification potential of unbounded rather than bounded adjectives and in distinguishing between degree and quantity modification, the latter only recently gaining attention in the cognitive-functional literature. The developmental path of good will be linked to its construal in terms of scalarity, the process of subjectification, and the categorial shift from modification to submodification.

The Intellectual Component of Labor Potential as a Factor of Sustainable Development of the Agricultural Sector

In the article, the proposition is substantiated that the current development of the agricultural sector is possible on condition of harmonization of environmental, social and economic factors based on the principles of consistency, balance and social justice. The paper examines the impact of the intellectual component of labor potential on economic growth in the agricultural sector. The study of the main types of production functions for macroeconomic analysis is conducted. The advantages of using the Cobb-Douglas production function in determining the levers of agricultural production growth in the context of sustainable development are substantiated. The present-day priority of activities intellectualization in the agricultural sector is proved. It is proposed to particularly focus on the use of intellectual assets of human potential for agricultural production intensification. The accomplished modeling of the agricultural sector sustainable development gives grounds for an optimistic forecast as to increasing the resource potential of agricultural production due to a growth in the quantitative and qualitative indicators of labor potential.