Channel Porosity Research Articles

High thermohydraulic performance of solar air collector utilizing high turbulence deflectors and porous media

In this research investigation, high thermohydraulic performance of a solar air heater is obtained utilizing a deflector attached to the back plate and inserted porous media in the channel that generators high turbulence. The optimum values of the geometrical parameters such as fin pitch 0.02m≤P≤0.04m,fin height 0.005m≤H≤0.02m and channel porosity 80%≤ϕ≤100% and flow parameter, i.e., Reynolds number 2000≤Re≤11000 are obtained using numerical investigation. The obtained results present impressive facts through contours of velocity and temperature, and ensured the manifestation of high heat transfer to the flowing air in the investigated design. It is revealed that due to the use of deflectors, the bulk fluid got deflected towards the hot absorber plate, while the both deflector plus porous media in the channel causes high turbulence and consequently high thermal and thermohydraulic (THPP) performance is achieved. Numerical results presented interesting results of occurring the wavy flow inside the design of porous solar air heater with deflector. The THPP of the deflector plus porous media design is obtainted as 15, while it is about 1.2 for the design consisting of only deflectors. The optimum value of the combined deflector plus porous media design is obtained as P = 0.04 m, H = 0.02 m, ϕ=95% and Re = 8000, while it is P = 0.06 m, H = 0.02 m and Re = 8000 for the only simple deflector design.

Experimental Study of Single‐Pass Fluid Flow With Convective and Sensible Thermal Energy Storage in a Porous Curved Channel Solar Air Heater

ABSTRACTIn this experimental research, a single‐pass solar air heater comprising a porous curved channel is investigated to reveal the scope of high thermal performance during the winter season. The investigation explores the geometrical parameters for the porous channel maintained by using steel wiremesh layers of wire diameter of 0.45 mm and pitch of 2.35 mm, and the number of layers ranging from 3 to 12, which presents the channel porosity, , from 99% to 96%, respectively. The curved porous channel offers additional fluid mixing, thermal backup, and high heat transfer area, thereby increasing the convective heat transfer to the air and consequently the thermal performance. A series of experiments were carried out under real outdoor conditions to examine the various factors such as variable channel porosity, air flow rate, and the amount of solar energy received. The findings revealed that the curved porous channel with a channel porosity of 96% results in the maximum thermal and thermohydraulic efficiencies of about 85% and 79%, respectively, and the outlet air temperature of 79°C.

Microfacies and Depositional Environments Analyses of the Hartha Formation at Balad Oil Field, Central Iraq

The Hartha Formation (Late Campanian-Maastrichtian) has been recognized as a potential reservoir for hydrocarbons in various oilfields within the Mesopotamian basin in central Iraq. The formation has conformable upper contact with the overlying Shiranish Formation but unconformable lower contact with the underlying Mushorah Formation. This formation has been stratigraphically divided into two main parts. The lower part is particularly significant as it is recognized as an important stratigraphic unit due to the presence of oil shows. Five subsurface sections and many thin sections of the Hartha Formation (Late Campanian-Maastrichtian) were studied to unravel the depositional facies and environments. The sedimentary microfacies of the Hartha Formation in the Balad oil field include mudstone, wackestone, wackestone to packstone, packstone, Packstone to Grainstone, and Rudstone. These depositional microfacies have been subdivided according to their primary and diagenetic constituents into six sub-microfacies. The microfacies have been deposited in deep shelf margin, open shelf, and foreslope of varying salinities and energy levels. Cementation, dolomitization, compaction and pressure solution (stylolitization ), and dissolution are observed affecting variably both ground mass and particles. These diagenetic processes have both positive and negative effects on porosity types, causing fluctuations in porosity levels. The primary pore types identified within the study wells include interparticle porosity, intercrystal porosity, moldic porosity, vuggy porosity, channel porosity, and fracture porosity.

Investigation on uneven flow distribution in triply periodic minimal surface heat exchangers

The development in manufacturing engineering has made it possible to adopt the unique porous structure known as the triply periodic minimal surface to increase energy efficiency in a variety of energy-related sectors. With the unique morphological characteristics, triply periodic minimal surface exhibits remarkable mechanical strength and thermal performance, which makes it a potential candidate for compact, high-performance heat exchanger constructions. In this study, a theoretical model based on triply periodic minimal surface porous media is developed. Based on the hypothesis that the triply periodic minimal surface is isotropic and the heat transfer intensity of fluid and solid is uniform throughout the core of the heat exchanger, the simulation of the full-size heat exchanger is simplified by using a porous media model. The flow distribution characteristics of triply periodic minimal surface heat exchangers, as well as the effect mechanism of key factors, including the channel porosity, header configuration, the type of triply periodic minimal surface, the core length and Reynolds number on the flow distribution performance, are investigated. A dual-header configuration is proposed to improve the flow uniformity of triply periodic minimal surface heat exchangers. The results indicate that the flow distribution performance of triply periodic minimal surface based heat exchangers can be enhanced by the reduction of channel porosity. When the cold-side porosity is 0.7, the flow rate deviates from the mean value by 220% at its maximum for a Primitive heat exchanger. A dual-header configuration eliminates the columnar extreme high velocity space in the core and greatly reduces the “weak zone” of flow distribution, which improves the flow non-uniformity by 45–90% over the single-inlet headers. This paper provides data and theoretical support for the optimal design and practical application of the complex, high-performance triply periodic minimal surface based heat exchangers.

Dipole Oscillations along Principal Coordinates in a Frozen Channel in the Context of Symmetric Linear Thickness of Porous Ice

The problem of periodic oscillations of a dipole, specifically its strength, along the principal axes in a three-dimensional frozen channel is considered. The key points of the problem are taking into account the linear thickness of ice across the channel and ice porosity within Darcy’s law. The fluid in the channel is inviscid and incompressible; the flow is potential. It is expected that the oscillations of a small radius dipole well approximate the oscillations of a small radius sphere at a sufficient depth of immersion of the dipole. It was found that during oscillations along the channel and vertical oscillations, waves are generated in the channel, propagating along the channel with a frequency equal to the frequency of dipole oscillations. These waves decay far from the dipole, and the rate of decay depends on the porosity coefficient.

Petrography and diagenesis of the Middle to Upper Jurassic succession from Sargelu section, northeastern Iraq

Petrographic and diagenetic analysis of the Middle-Upper Jurassic successions (Sargelu, Naokelekan, and Barsarin) formations and boundaries between them in the Sargelu area, Kurdistan region, N.E. Iraq was conducted based on the lithologic description, thin section analysis, and scanning electron microscopy. The study aims to define the petrographic components and diagenetic processes that affect the carbonate rocks of Jurassic succession in the studied section. Thirty-eight thin sections have been prepared, with five samples selected using the S.E.M. technique to reveal the petrographic components and diagenetic processes. The Jurassic succession is composed mainly of carbonates (limestone and dolostone) interbedded with shale units. Petrographically, the Sargelu, Naokelekan, and Barsarin formations are composed of skeletal grains (pelagic pelecypods, radiolaria, calcispheres, planktonic and benthonic foraminifera such as miliolid, ostracods, bioclasts, and stromatolites) which are the most common, in addition, non-skeletal grains such as poloids, micritic groundmass, and recrystallized micro spars, Many diagenetic processes affected the studied carbonate rocks such as micritization, dolomitization compaction and stylolite formation, authigenic minerals (pyrite), cementation, neomorphism, dissolution and porosity formation as represented by moldic, vuggy, channel and fracture porosity.

Assessing Endokarst Potential in the Northern Sector of Santo António Plateau (Estremadura Limestone Massif, Central Portugal)

Karst is a peculiar natural landscape arising from high rock solubility and well-developed underground solutional channel porosity. It is unique for its surface relief (exokarst) and subsurface drainage, including cave systems (endokarst). In Portugal, karst areas mainly consist of marginal or low-density territories with great fragility and vulnerability and great geo-environmental richness that merits better policies and practices regarding their geo-conservation. Endokarst potential assessments can provide decision-makers and local authorities insight into present and future territorial management and planning. In this context, the main objective of this study was to produce a cartographic model to identify areas with a greater probability of containing karstic caves—i.e., a greater endokarst potential—in the northern sector of the Santo António Plateau (Estremadura Limestone Massif, Central Portugal). Geological, topographic, hydrogeological, and land cover data were collected, processed, and integrated into a spatial database using a Geographic Information System. The locations of known cave entrances in the study area were also identified from local public institutions and speleological team records. Subsequently, four conditioning factors were extracted from the data: lithostratigraphic units, fracture density, relief energy, and land cover. Using a multi-criteria decision-making analysis, each previously chosen conditioning factor and its respective classes were weighted using an analytic hierarchy process. The locations of known cave entrances served to evaluate the cartographic model built, with results showing an agreement of 81.9%. This prototype of the endokarst potential map for the study area may be used for strategic and operational environmental planning (at least on a local scale) to assist decision-makers, competent authorities, and local speleological teams. Its application may promote a more accurate and thoughtful definition of areas to be investigated, substantially reducing the time and costs associated with field prospecting.

An Approach to Define and Quantify Porosity System in Heterogeneous Carbonate Reservoirs through Textural Analysis using High-Resolution Resistivity Image in the Bassein Formation of Mumbai Offshore Basin, India

Summary In evaluating the porosity system of the Bassein formation, high-resolution resistivity image (FMI) data have been used. Major features observed from the FMI data are the presence of low-angle fractures and solution channels of varying length and thickness. Against the layers with very-low-density neutron porosity, solution channels are seen as conductive features. These mud-filled solution channels can actively participate in production. Being very small-scale features, these types of porosities are not identifiable from conventional log data. To define and quantify porosity types such as vugs, solution channel, and matrix porosity, the resistivity image data are processed and image-based porosity is calculated. A core thin-section study is carried out and is used for calibration of the image-derived porosity system. Using resistivity image data, we have computed porosity types, for example, vugs, connected matrix and resistive, and their contribution to total porosity. Identification of hydrocarbons in reservoir layers with their porosity contribution (porosity partitioning) gives better insight into hydrocarbon production in these low-porosity layers which are producing after acid job.

Modeling the velocity profiles in Vanadium Redox flow batteries-Serpentine flow field

Simulations are performed to study the effect of performance parameters on the velocity profiles in a vanadium redox flow battery. The effect of flow rate, viscosity, porosity, electrode thickness, and effect of channel height on the velocity profile in a vanadium redox flow battery are studied. Quantitative analysis of velocity profiles at the mid height of channel, at the channel-electrode interface and mid height of electrode thickness is done. The channel height, thickness and porosity are found to have a substantial effect on the velocity profiles across the battery. It was found that the velocity in the electrode-channel interface is about 3 orders of magnitude lower than velocity in the channels.

Upper Palaeogene-Lower Neogene Reservoir Characterization in Kirkuk, Bai Hassan and Khabaz Oil Fields, Northern Iraq

The Upper Palaeogene-Lower Neogene succession represent subsurface sections from Kirkuk, Bai Hassan, and Khabaz oilfields were divided to many reservoir units dependent on information derived mainly from petrographical description, well log analysis, and related microfacies. In Khabaz oil Field, the hydrocarbon reservoir includes three reservoir units covered the Jeribe Formation, Anah Formation with its interfingering zone with Azkand Formation and Azkand Formation, the total thickness of this reservoir reaches up to (128 m) with net pay thickness of about (85.7 m) and net average porosity of (0.096) while the net water saturation is (0.185), the volume of shale is (7.130). The hydrocarbon reservoir in Bai Hassan was represented by three reservoir units comprised from the Bajwan and Baba formations, the total thickness of this reservoir is (178 m) with net pay thickness of (154.2m) and net average porosity of (0.121) while the net saturation is (0.156), the volume of shale is (36.837). Four reservoir units comprised the hydrocarbon reservoir in Kirkuk Field where they covered the Bajwan, Baba, Shurau and Sheikh Allas formations. The total thickness of these reservoirs is (136 m) with net pay thickness (124.5m) and net average porosity (0.178) while the net water saturation is (0.159), the volume of shale is (5.82). Many types of porosity were associated with these reservoirs such as the interparticles, intraparticles, intercrystaline, fracture, channel, moldic, vug, and cavern porosities. These porosities are attributed to a combination of dolomitization, fracturing, and dissolution.

Improvement of thermal-hydraulic efficiency of mining power equipment through the application of porous freon steam generators with high heat conductivity

In the article, various areas of technical application of porous freon steam generators in mining power equipment are described, and explanations why freon coolants can provide a positive energy effect in such facilities are given. The paper presents results of calculations of thermal-hydraulic efficiency of the porous once-through tubular steam generators with freon-12 as a model working fluid in the the laminar flow area and with boundary conditions of the first kind. The smooth-wall cylindrical channels with different diameters were used as the reference surfaces to be compared. The following mode and design parameters were taken as a calculation base: the liquid temperature and pressure on the saturation line at the entry into the channel were: Ts0= 110 °С; P0s = 39,9·105 N/m2.; temperature heads, i.e. a difference between the wall temperature and temperature of the liquid at the entry into the channel were: ΔT=Tw-Ts0 = 1 °C; 2 °C; 3 °C; 4 °C; 5 °C; the Reynolds numbers at the entry into the channel were: Reo = 100; 200; 500; 1000; 2000; 2300; the channel porosities were: θ = 0.7; 0.75; 0.8; 0.85; 0.9. The porous material was metal felt with the copper fiber diameter of 200 microns. The channel diameters were: d =3·10-3 m; 4·10-3 m; 5·10-3 m; 6·10-3 m; 7·10-3 m. On the basis of the performed computational studies, it was concluded that for the conditions of the same mass flow rates of the coolant, with laminar flow, and the same channel diameters, it is possible to achieve a significant reduction in the length of the porous once-through steam generator in comparison with the length of the smooth-wall once-through steam generator. Due to the significantly shorter length, differential pressure for pumping the coolant can be several tens of percent less in porous evaporation channels than in the similar smooth-walled channels. This computational study also made it possible to establish main regularities in dynamics of the energy efficiency coefficients and their dependence on the model mode and design parameters. It was shown, that positive dynamics of the efficiency coefficients of porous steam generators occurs with decrease of the channel diameter and temperature head, as well as with increase of the Reynolds number in the investigated region of coolant laminar flow.

Подход к определению коэффициента теплообмена между породой и смесью флюидов при моделировании процессов неизотермической многофазной фильтрации

The paper presents an approach to calculation of the coefficient determining the rate of heat transfer between a fluid mixture in oil reservoir and a matrix-rock. This coefficient is necessary for further joint modeling of hydrodynamic and thermal processes that occur in the field reservoir during its development using, for example, thermal methods for enhanced oil recovery. To model the processes of a non-isothermal multiphase flow, an approach based on implicit pressure calculation using the finite element method and explicit calculation of phase saturations is used. The approach to determining the heat transfer coefficient is based on solving the thermal problem in an area corresponding to a channel of a porous medium and a part of the matrix-rock around it. In this case, a fluid mixture with a known temperature value, different from the initial temperature in the channel and matrix-rock, enters the channel at a given rate. A two-dimensional problem is solved in an axisymmetric formulation by the finite element method.Numerical experiments to determine the heat transfer coefficient were carried out on models for various values of the channel size, porosity, initial temperatures of the medium, temperature of the mixture entering the channel, thermal properties of the fluid mixture and rock. As a result of the study, it was found that the channel size and porosity have the most significant effect on the value of the heat transfer coefficient, since these characteristics determine the volume of the matrix-rock, which should “warm up / cool down” when the temperature of the fluid mixture in the channel changes. Also, the coefficient values obtained were quite large, since the heat exchange between the rock and the mixture in the channel occurs in minutes, which practically corresponds to instantaneous heat transfer when it comes to modeling field development processes, where time steps are days and months.

Dynamic evolution of membrane biofouling in feed channels affected by spacer–membrane clearance and the induced hydrodynamic conditions

Membrane biofouling is regarded as a Gordian knot in applying reverse osmosis and nanofiltration for water treatment. It occurs in the feed spacer channels of spiral wound membrane elements. The influence of feed spacer structure on hydrodynamic condition and biofouling development remains yet to be fully understood. This study aims to quantify the dynamic evolution and spatial distribution of biomass in feed spacer channels, and reveal the great importance of spacer–membrane clearance in the biofouling development. Four kinds of feed spacers with the same thickness (28 mil) but different clearance width, by varying filament diameter (0.4, 0.45, 0.55 and 0.6 mm), were used. A relatively long-term (20 d) biofouling experiment was conducted by using a feed solution of lower bacterial load and nutrient dosage. Results showed that the “shear stress effect” dominated the early stage of biofouling as biofilm was first attached to the low-shear regions, regardless of the spacer–membrane clearance width. In the middle and late stage, the “blocking effect” emerged with the continuous accumulation of biomass, as was especially the case in the feed channel with narrow spacer–membrane clearance. In this period, biofilm was prone to deposit and block the narrow flow passage between the spacer filaments and membrane surface, which decreased the uniformity of flow field, expanded the flow “dead zone” area, boosted the feed channel pressure (FCP) drop, and resultantly accelerated the rate of membrane biofouling. Enhancement of the “shear stress effect” under an appropriate range of spacer–membrane clearance width and thus channel porosity, as well as customed design of feed spacer geometries according to specific fouling locations are suggested for the future optimization of feed spacer.

Evolution of lamellar architecture and microstructure during redox cycling of Fe-Co and Fe-Cu foams

The effects of alloying Fe with 25 at% Co or 30 at% Cu are studied in freeze-cast lamellar foams subjected to redox cycling under H 2 - and H 2 O-rich atmospheres at 800 ºC, relevant to metal-air batteries. In unalloyed Fe foams, redox cycling causes irreversible Kirkendall porosity growth within lamellae, leading to fracture and buckling in the lamellar architecture which in turn leads to foam densification after a few cycles. By contrast, Fe-25Co lamellae develop, upon oxidation, a pure Co core and a Fe 3 O 4 shell which decreases buckling and Kirkendall pore growth, thus slowing sintering and densification of the lamellar foams. After Fe 3 O 4 reduction, the Fe-rich shells and Co-rich cores of the lamellae re-homogenize by diffusion to the original single-phase Fe-25Co alloy, achieving a reversible microstructure upon a full redox cycle. After 10 cycles, average channel porosity (between lamellae) undergoes only a small decrease (from 62 % to 46 %), with minimal Kirkendall pore coarsening in the lamellae, consistent with strong sintering resistance in the Fe-25Co foams. The Fe-30Cu foams also display lamellae with Cu core and a Fe 3 O 4 shell structure after oxidation, since Cu, like Co, does not oxidize under steam. However, the lack of solubility of Cu in Fe prevents re-homogenization after Fe 3 O 4 reduction, so the resulting Cu-core / Fe-shell lamellae undergo severe sintering and densification upon subsequent redox cycling, with channel porosity reducing from 61 % to 9 % after just 5 cycles. For both systems, operando x-ray diffraction during redox cycling reveals that Cu, unlike Co, doubles the Fe oxidation rate, as compared to pure Fe foams. • Fe-25Co and Fe-30Cu metallic foams are created with high porosity and lamellar architecture. • Operando X-ray diffraction is used to track H 2 /H 2 O redox reactions in these foams at 850 °C. • Fe-25Co foams show excellent stability over 10 full redox cycles at 850 °C. • Fe-30Cu foams sinter during cycling, but Cu accelerates redox kinetics.

Microstructural evolution of lamellar Fe-25Ni foams during steam-hydrogen redox cycling

Cyclical steam oxidation and hydrogen reduction, relevant to iron-air batteries, is performed on freeze-cast Fe-25Ni (at.%) foams consisting of colonies of parallel lamellae separated by channels, both ∼20 µm thick and millimeters in length. This structure is designed to accommodate volumetric changes associated with the cyclical oxidation and reduction of Fe. Metallographic imaging performed at various redox stages, together with time-resolved in situ X-ray diffraction during redox cycling, detail the reaction kinetics and phase evolution of the foam, the evolution of its lamellar microstructure, and the eventual degradation of its internal architecture. As Fe preferentially oxidizes over Ni, each lamella develops an outer Fe-oxide scale, with metallic Ni rejected to the cores of the lamellae which develops an interconnected network of Fe-oxide veins. The Ni-rich metallic core limits the accumulation of Kirkendall pores and provides adhesion to the Fe-oxide scale, thus preventing lamellar fracture observed in unalloyed Fe foams. While the oxidation rate is slowed by the presence of Ni, the reduction rate is accelerated, as Ni acts as a catalyst and as the network of oxidized veins reduces quickly and become open microchannels, thereby providing rapid hydrogen access (driving reduction) and steam egress to the lamellar interior. After complete reduction, the Fe-rich shell and the Ni-rich core interdiffuse and homogenize, which helps eliminate both Kirkendall pores and microchannels from the lamellae. Furthermore, the ductile Ni-rich core limits lamellar buckling (another densification mechanism active in Fe foams). Architectural changes also affect resistance to internal damage, with smaller lamellar colonies exhibiting better resistance to buckling. These combined effects provided by Ni alloying allow the Fe-25Ni foams to maintain a high channel porosity (>40% porous), and thus high active surface area, after 10 redox cycles, as compared to a near complete loss of open channel porosity reported in unalloyed Fe foams.

The critical role of feed spacer channel porosity in membrane biofouling: Insights and implications

Membrane biofouling is a major hindrance limiting the efficiency of spiral wound membrane (SWM) module for water treatment. Feed spacer is an imperative component of SWM module which creates feed channels, determines fluid field and thus influences biofilm development via its geometry. Yet, the role of feed spacer channel porosity in biofilm development remains unclear. In this study, 16 feed spacers of varied geometric parameters and thus different channel porosities were used for both numerical simulations and biofouling experiments. Results showed that the hydraulic and anti-biofouling performances were more sensitive to the variation of filament diameter and spacer thickness. Feed channel porosity as a gross parameter played a pivotal role in biofouling development. The high-porosity (> 0.85) feed spacer channels exhibited a slower increase of feed channel pressure drop when biofouling occurred, but with more biomass accumulated in the middle of spacer meshes because of lower shear stress. For the low-porosity (< 0.75) channels, biofilm incipiently developed from the interspace region between spacer filaments and membrane surface due to “block effect”, which aggravated “narrow channeling” and induced a larger area of dead zone, leading to more severe biofouling ultimately. An appropriate channel porosity was suggested at ∼0.85 based on the hydraulic and anti-biofouling performances conjointly in this study.

Characterization of gas transport in shale: A multi-mechanism permeability modeling approach

Accurate characterization of gas transport in shale is crucial for many industrial processes and scientific issues, such as CO2 sequestration in depleted shale and shale gas production. Gas transport in shale involves complex chemical, hydraulic, and mechanical effects and is generally characterized by permeability. Laboratory observations show some “abnormal” permeability evolution behavior which cannot be explained by classical shale permeability models. In this research, we develop a generic shale permeability model that couples multiple gas transport mechanisms and explains complex permeability evolution. Shale is idealized as an improved sugar-cube structure with inorganic flow channels and composite flow channels penetrating organic and inorganic zones. In organic zones, gas rarefaction effects, multilayer adsorption, multilayer-adsorption-induced swelling, stress sensitivity, and surface diffusion are considered. For inorganic zones, gas rarefaction effects and stress sensitivity control gas transport. Based on this conceptual geometry, the variation of flow channel size, effective stress, porosity, tortuosity, and permeability is coupled. The permeability model can be degraded into different forms that are suitable for constant confining pressure, constant effective stress, and constant average pore pressure conditions. The model is verified against experimental data involving different permeability evolution trends. The comparison among this model and several classical models further demonstrates its advantage and uniqueness. Simulation results show that shale permeability is determined by the competitive effects of gas rarefaction phenomenon, sorption-induced organic matter swelling, and effective stress variation. Before and after pore pressure reaches a switch pressure value, the dominant mechanisms for permeability evolution are different. We use the switch pressure to drawn two controlling factor diagrams that demonstrate the dominant mechanisms in different realms of permeability evolution during gas injection or depletion.

Utilising fractional porous interface for high thermal performance of serpentine wavy channel solar air heater

This work investigates the thermohydraulic performance of a porous serpentine wavy channel solar air heater. Comprehensive illustration on the effect of fractional porous interface (25%≤ξ≤100%), channel porosity (90%≤φ≤100%) and Reynolds number 2000≤Re≤11000 on the thermohydraulic performance of solar air heater design is presented. Experiments are performed and numerical results are validated to conduct further investigations for the optimization of the input variables. This study is a unique idea that broadly presents the scope of thermal performance improvement by utilizing the porous media in fraction and varying porosity in solar air heater channel and highly useful for the researchers of this field. Finite volume method based computational fluid dynamics tool is used to conduct numerical investigations, Forchheimer equation is used to account the effect of porous media and surface to surface (S2S) radiation model to capture the effect of shape factor and emitted radiation in collector channel. It is obtained that ξ of 25% and φ of 93% delineated the best thermohydraulic performance (THPP) of 4.52 for the present solar air heater design. While, the obtained thermohydraulic performance is 186% times higher compared to the smooth design. The excellent results that come into the light from numerical investigation are the secondary flow formation in the porous and flow zones at higher Reynolds number and lower fraction of porous region (ξ), and for all configurations of ξ at large channel porosity (φ). Hence, results of this investigation not only present the best operational configuration to obtain higher thermal performance, but also present the measures to reduce the material cost of porous media and consequently pumping power.

Sponge-like carbon monoliths: Porosity control of 3D-printed carbon supports and its influence on the catalytic performance

Sponge-like carbon monoliths with tailored channel architecture and porosity were prepared by combining sol–gel polymerization and 3D printing technology. The pore size distribution (PSD) and macropore volume were controlled by varying the water concentration used in the synthesis. The size and interconnection degree of primary particles, and consequently the pore width and macropores volume, increases by increasing the water concentration. However, a more heterogeneous PSD was detected at high water concentration, due to the better-defined spheres-like morphology of primary particles which leaves voids and corners between fused spheres together with bigger macropores leaves by the coral-like structure. The role of this porosity control on the CuO/CeO2 catalytic performance was pointed out in the CO-PrOx reaction. The CuO/CeO2 dispersion and distribution along the carbon network increases by increasing the water concentration, i.e. the pore width and macropore volume, enhancing the catalytic activity. However, this improvement is not observed at high water concentration in which preferential flow pathways are created favored by the heterogeneous PSD. This manifest that the porosity control plays an important role in the catalytic performance of monolithic catalysts and thus, the monolithic support must be specifically designed to optimize the catalytic performance of active phases for each application.

High-Throughput Optimal Design of Spacers Using Triply Periodic Minimal Surfaces in BWRO

The development of advanced feed spacers under different working conditions can enhance the performance of the reverse osmosis (RO) desalination process. The 3D-printed experimental results on triply periodic minimal surfaces (TPMS)-based spacers in previous literature indicate that the spacers have higher permeation flux of water compared to those of the common commercial spacers. In this paper, a hybrid modeling approach is developed and applied to predict and evaluate the performance of TPMS-based spacers. The effect of feed channels’ height and porosity on the performance of spacers in brackish water RO (BWRO) process is studied by using a high-throughput approach. The predicted pressure drop by new simulations using the TPMS-based spacers (≈0.09–0.27 bar) from inlet to outlet in a typical two-stage BWRO system is reduced by more than 89% than that of using the commercial spacer (≈2.57 bar). Using the designed advanced spacers, the average permeation flux of water increases more than 8.6% compared to that of the commercial one. With the increase in feed channel height and porosity, the performance of spacers is gradually improved. TPMS-based spacers have significant industrial application prospects.