Terms Of Pressure Drop Research Articles

A numerical study of microtube geometry effect on flow boiling using the volume of fluid method

Other than pursuing high heat flux, pressure drop also plays a key role in microtube applications as the power and efficiency of a pump are determined in terms of pressure drop. In the literature, only a few studies focus on how tube geometry influences pressure drop. This study numerically investigates the geometry effect on microtube flow boiling and pressure drop using the volume of fluid (VOF) method. Three types of geometries are used in this study: divergent, normal, and convergent microtubes with different lengths and hydraulic diameter ratios. The transient developments of vapor formation, heat flux, and pressure drops are presented within 200 ms. It is shown that the total pressure drop in the divergent microtube is the lowest. The heat flux is decreased as the massive vapor bubbles clog the tube. However, the shortened divergent microtube can increase the heat flux up to 38713.1 W/m2 and reduce the pressure drop down to 214.24 Pa, compared to the normal one under certain flow conditions, while the tube-clogging effect is not dominant. A larger inflow mass flux can delay the vapor bubble formation on the heated wall, which is beneficial to prevent the tube clogging and leads to a higher heat flux. On the other hand, higher heat flux can be achieved in the convergent microtube due to the increasing velocity inside the tube, although it induces the highest total pressure drop. This study provides a better fundamental understanding of the microtube geometry effect on flow boiling and relevant physical insight for the future design of microscale heat transfer applications.

Particle-scale modelling of rapid granular filtration in a dual-media filter

Multi-media filters are widely applied in water treatment, yet the understanding of powder transportation mechanisms at particle-scale and clogging prediction is still lacking. In this work, a dual-media (anthracite and sand) rapid granular filtration is numerically studied at particle-scale by a smoothed computational fluid dynamics-discrete element method (CFD-DEM) model. In this model, a multi-sphere model and a modified Johnson-Kendall-Roberts (JKR) model are integrated to describe anthracite shapes and material cohesion, respectively. The model is validated in terms of pressure drop across a packed bed and powders migration through another packed bed. The powder transportation in the filtration through a dual-media filter is studied. The results show that the motion of powders in the anthracite layer are governed by deposition, penetration, and connection, while the motion of powders in the sand layer experience core formation, core growth, and cluster connection. The evolution of solid volume fraction Φ indicates a saturation value (0.67) exists in the entries of layers. The small powders tend to be clogged in the anthracite layer and the large powders prefer to be clogged in the sand layer. The density evolution of the clogged powders nv shows that the sand layer has a saturation nvs=0.21 in the entry, and that of the anthracite layer nva=0.252 is obtained by extrapolation. Finally, a probabilistic model is originally derived for quantifying the clogging by clogging probability. After verification, the sand layer has the clogging probability of 0.47 while the anthracite layer has the clogging probability of 0.10.

Fluid dynamics and thermal characteristics of a conical bubbling fluidized bed riser

Conical fluidized beds show a unique inherent dynamic feature due to a lower pressure drop than conventional fluidized beds. Although the literature deliberating on the hydrodynamics of this type of riser is rich, the thermal characteristics of this type of riser are yet to be investigated. Moreover, the interphase heat transfer has not been deeply understood in previous literatures by considering the effect of air velocity. As in real fluidized bed industries, hot air is supplied through the inlet of a riser to heat the particles in the drying process and other phenomena. As a result, the interphase heat transfer characteristics are more important than the core-to-wall thermal characteristics. The thermal phenomena are ineluctably directed by the two-phase flow hydrodynamics. The present investigation is conducted to research fluid dynamics and interphase heat transfer phenomena of the air-sand mixture in a conical bubbling fluidized bed riser of cone angle 10° with varying inlet air velocity. Air velocity is the main parameter which leads to the fluidization in fluidized beds. It is this parameter that materializes the elutriation of particles and determines the nature of the bed, whether bubbling or recirculating. This, in turn, affects the heat transfer and overall efficiency of the bed. Experiments along with corresponding three-dimensional (3-D) numerical simulations are performed at five superficial air velocity conditions (1, 1.25, 1.5, 1.75 and 2 m/s) and a 30 cm height of bed materials. The results are then compared between experimental and simulation conditions. Both the experimental and 3-D numerical results indicate that a velocity of 2 m/s results in the lowest pressure drop of 2830 Pa. Similarly, the average bed temperature in this velocity is 444 K which is the highest, whereas the interphase heat transfer coefficient is 320 W/m2K. The bed-to-wall heat transfer coefficient is found to increase by 47.2% and 45.8% at the central axial locations of 10 and 20 cm, respectively. Hence, it can be concluded that air velocity plays an important role in the operation of a fluidized bed in terms of pressure drop, heat transfer and thermal efficiency. Air velocity of 2 m/s is found to be the best value for the present study because the bed pressure drop decreases and heat transfer increases.

Upper Airway Flow Dynamics in Obstructive Sleep Apnea Patients with Various Apnea-Hypopnea Index.

Background and aim: This study evaluates the upper airway flow characteristics, anatomical features and analyzes their correlations with AHI in patients with varied degrees of OSA severity seeking for discernments of the underlying pathophysiological profile. Materials and Methods: Patient-specific computational fluid dynamics models were reconstructed from high-resolution cone-beam computed tomography images for 4 OSA patients classified as minimal, mild, moderate, and severe according to AHI. Results: The parameters, minimal cross-sectional area (MCA), and the pharyngeal airway volume did not show clear correlations with the OSA severity defined according to AHI. No correlations were found between the classically defined resistance of the airway in terms of pressure drop and AHI. The flow analysis further showed that the fluid mechanisms likely to cause airway collapse are associated with the degree of narrowing in the pharyngeal airway rather than AHI. Results also suggested that some patients classified as severe OSA according to the AHI can show less susceptibility to airway collapse than patients with relatively lower AHI values and vice versa. Conclusions: The relative contribution of anatomical and non-anatomical causes to the OSA severity can significantly vary between patients. AHI alone is inadequate to be used as a marker of the pathophysiological profile of OSA. Combining airflow analysis with AHI in diagnosing OSA severity may provide additional details about the underlying pathophysiology, subsequently improving the individualized clinical outcomes.

CFD modeling and simulation of the hydrodynamics characteristics of packed column with structured sinusoidal corrugated sheets packings

In this study, the hydrodynamics characteristics of packed column with structured sinusoidal corrugated sheets packings were investigated by computational fluid dynamics (CFD) modeling and simulation method. The proposed CFD model was first validated by comparing simulation results with those of experimental data in terms of pressure drop under different inlet gas velocities. Then the effects of wave length, amplitude, angle and placement method on dry pressure drop were studied by control variable method. The relationship between F factor and pressure drop with different packing structures were investigated. The flow fields of pressure and velocity were analyzed and then used to calculate the resistance coefficient of structured packings. This simulation study can contribute to the evaluation and optimization of multiphase flow characteristics and the mass transfer performance of packed column.

Experimental and Numerical Study of Flow Through Horizontal Wellbore of the 180 Perforation Phasing

This paper demonstrates experimental and numerical studies to investigate in perforation pipes with a phasing 180° and perforation densities 9 spm in a horizontal wellbore. The experimental study was conducted to investigate the phasing angle 180° in a horizontal wellbore. The wellbore has an inner diameter of 44 mm, as well as the length of the pipe is 2 m. For this purpose, a simulation model was created in the wellbore using the ANSYS FLUENT simulation software by using the standard k-𝜖 model and applied to the (CFD) with changing the axial flow from (40 - 160) lit/min and constant inflow through perforations from range (20 - 80) lit/min. Concerning the findings of this study, it was noticed that the total pressure drop (friction, acceleration, mixing) goes high as the total flow rate ratio increases. As well as, an increase of the inflow concerning the main flow rate ratio leads to an increase in the total pressure drop and a decrease in the productivity index. Furthermore, the percentage error of the total pressure drop between the numerical and experimental results in test 4 is about 5.4 %. Also, the average velocity goes high with increasing the total flow rates and the velocity keeps increasing along the length of the pipe until it reaches its maximum value at the end of the pipe due to the effect of the perforations. It was concluded that there are the numerical and experimental results reflected a good agreement concerning the study of the flow-through perforations at 180° angle in terms of pressure drop and apparent friction factor, etc.

Three-dimensional MHD flow in moderate change ratio orifice

In fusion reactor blanket design, liquid metals are attractive working fluids since it is possible to combine in a single fluid the functions of coolant, tritium carrier and breeder. These electrically conductive fluids flow in the presence of a strong magnetic field, inducing the appearance of Lorentz forces and magnetohydrodynamic MHD effects. Increased pressure loss, particularly in complex geometry elements, is a critical point for blanket design. The MHD flow through an orifice plate made by electroconductive walls (c = 0.01 ÷ 0.1) has been analysed in this paper using ANSYS CFX in the range Re = 108, and Ha = 0 ÷ 300. A wide recirculation region is detected after the flow exits the orifice, with potentially harmful consequences for efficient tritium removal. Large pressure loss occurs in the orifice due to conductive wall and non-negligible axial length. The 3D pressure drop term is characterized through a local resistance coefficient (k) that is found to be k ≈ 0.205 for well conducting walls (c = 0.1) and k ≈ 0.063 for poorly conducting ones (c = 0.01).

Study of spacer structure on the enhancement of heat and mass transfer in direct contact membrane distillation modules

Membrane distillation technology, which combines the membrane process with evaporation, has many benefits, including operation at atmospheric pressure, simple configuration, usage of low-grade heat sources, etc. In the current work, a new type of curved spacers was invented for the direction contact membrane distillation. A three dimensional numerical method was established, which coupled the transmembrane mass transfer with fluid flow in the channel by adding user-defined functions. Different distances between the spacer and the top wall, defined as d, were studied. 4 straight spacers (Sd0, Sd1.5, Sd3,Sd4.5) and 4 curved spacer (Cd0, Cd1.5,Cd3,Cd4.5) were investigated in detail. The curved spacers performed better in mixing and enhancing permeate flux than the straight spacers. The averaged performance enhancement factor (αc) was introduced to evaluate the performance enhancement of the curved spacers compared to the straight spacers. When d was 1.5 mm, αc was 1.33, which was the maximal among the studied cases. The curved spacer performed better in terms of heat transfer, but at a considerable cost in terms of pressure drop. The comprehensive evaluation index (Pec) was proposed to evaluate the overall performance of heat transfer and pressure drop. Pec varied with Reynolds number (Re) and spacer configurations. When Re was in 200 - 550, the maximal value of Pec was achieved by Cd1.5 spacer. When Re was in 500 - 920, the maximal value of Pec was achieved by Cd3 spacer.

Numerical Simulation of the Cleaning Performance of a Venturi Scrubber

Industrial applications need to use different systems for the problem of gas cleaning. A lot of processes have been developed, such as the use of a venturi for gas cleaning and pollution reduction. Additionally, several studies have been developed especially in terms of pressure drop because it is one of the main parameters to determine its efficiency. While the phenomenon of mass transfer in a venturi scrubber has not found much attention, in the present study, a mass transfer two-dimensional simulation is developed for gasification gas cleaning through a venturi scrubber with boundary conditions represented in air inlet velocities of 10, 15, and 20 m/s and water inlet mass flow of 0.02, 0.04 and 0.06 kg/s. In this work, Navier–Stokes equations are solved numerically and the mass transfer technique is treated by the volume of fluid (VOF) model, using CFD software. The obtained results were analyzed by presenting the mass fraction, velocity and pressure contours, and profiles. The probability density function (PDF) of mass transfer is studied too, showing how the removal efficiency of the venturi scrubber increases with a decrease in the liquid flow rate and an increase in the gas velocity. Therefore, the results show that the proposed venturi has the best mass transfer performance with a PDF that reaches 97.6 for velocity liquid of 20 m/s and the removal efficiency showed higher values at low liquid flow rates.

Performance assessment of lift-based turbine for small-scale power generation in water pipelines using OpenFOAM

In-pipe water turbines have begun to gain interest for harvesting power on a small scale from pipe networks. However, few studies have addressed the feasibility of installing spherical lift-based helical-bladed turbines in a water supply network. Points such as the pressure drop and generated power remain unexplored. In this study, a three-dimensional numerical model, based on OpenFOAM, is used to investigate the performance of the spherical lift-based helical-bladed in-pipe water turbine. The study aims to evaluate how the geometric properties of this turbine affect its performance in terms of power and efficiency, and the hydraulics of pipe flow in terms of pressure drop. The study considers a turbine of diameter 600 mm, with the following geometric properties: number of helical blades 3, 4 and 5; blade chord length 10%, 15% and 20% of turbine diameter D; blade helicity 0°, 60° and 120°; and pitch angle −6°, −3°, 0° and 3°. These parameters are analyzed at tip speed ratios (TSRs) of 2, 3 and 4. The results show that the five-blade turbine yields a power of 1300 W, while the three-blade turbine yields only 870 W, at an optimum TSR of 3. A change in the chord length of 50% (from 0.10D to 0.15D) increases the turbine power by 88.4% and efficiency by 40% for the same TSR. A further change to 0.20D gives no significant improvement in efficiency or power output. An increase in the helical angle from 0° to 120° results in a 22.8% reduction in turbine power. The turbine achieves the maximum power output of 1350 W at zero pitch angle, with a corresponding efficiency of 27%. The maximum head loss observed is 1.6 m, which represents 2.7% of the total head in the pipe. Solidity has a more pronounced effect on head losses than helicity and pitch angle.

Experimental and Numerical Analysis of an Innovative Mixer Geometry for Urea Injection in SCR Applications

Selective catalytic reduction (SCR), based on the injection of urea-water-solution (UWS), is one of the prevailing and more effective approaches to reduce NOx emissions in diesel engines. To improve the performance and durability of the system, it is crucial to develop reliable simulation tools able to correctly describe not only the urea conversion into ammonia and the mixing with exhaust gases but also the possible formation of solid deposits along with the engine’s exhaust line.In the present paper, two different exhaust systems for off-road applications are analyzed, both of them consisting of a diesel oxidation catalyst (DOC) followed by a diesel particulate filter (DPF), a UWS injection and a mixing device, and an SCR catalyst. Two alternative UWS mixing subsystems are evaluated, including a newly developed design. A 3D-CFD numerical analysis is carried out to assess the performance of both systems in terms of pressure drop, UWS spray, and liquid film development, in addition to flow velocities and species concentration uniformities at SCR catalyst inlet. A detailed analysis of droplet impingement on walls and liquid film development is enabled, thanks to a conjugate heat transfer (CHT) approach. Moreover, a deposit risk index is used to identify the areas of the systems where urea deposit formation is expected.Eventually, numerical results are compared with experiments on one operating condition chosen as the most challenging in terms of exhaust temperature and flow rate, both in terms of systems NOx conversion efficiency and deposit formation, showing a satisfactory agreement, thus paving the way to use the proposed synergetic numerical and experimental approach to further optimize the design and the system’s performance.

Design and characterization of Kenics static mixer crystallizers

Tubular crystallizers are desirable for continuous operations because they can approach plug flow conditions, achieve higher throughputs, and can be easy to control. However, the possible limitations of tubular crystallizers may include settling of crystals, fouling and higher pressure drops at longer residence times. The performance of a tubular crystallizer with gaps between the Kenics type mixing elements is characterized and compared with a standard Kenics static mixer and a hollow tubular crystallizer for the crystallization of lysozyme from solution. The gapped Kenics static mixer crystallizer provides an attractive trade-off between the standard Kenics static mixer and the hollow tubular crystallizer in terms of mixing length, shear rate, residence time distribution, pressure drop and segregation or settling of crystals. Furthermore, the gapped Kenics static mixer crystallizer and the standard Kenics static mixer crystallizer exhibit a similar crystallization performance in terms of desupersaturation profile and mean crystal size at the outlet for different initial lysozyme concentrations and seed loadings. The advantages of the gapped Kenics static mixer crystallizer in terms of pressure drop and minimization of crystal settling allow for lower flow rates and longer residence times under plug flow conditions, which has important practical benefits for continuous crystallization.

Porosity Effect of the Silver Catalyst in Hydrogen Peroxide Monopropellant Thruster

In monopropellant system, hydrogen peroxide is used with catalyst to create an exothermic reaction. Catalyst made of silver among the popular choice for this application. Since the catalyst used is in porous state, the effect of its porosity in the hydrogen peroxide monopropellant thruster performances is yet unknown. The porosity changes depending on factors including catalyst pact compaction pressure, bed dimension, and type of catalyst used. As researches on this topic is relatively small, the optimum porosity value is usually left out. The performance of the thruster indicated by the pressure drop across the catalyst bed. Porosity of the catalyst bed adds additional momentum sink to the momentum equation that contributes to the pressure gradient which lead to pressure loss inside thruster. The effect of porosity influences the performance and precision of the thruster. Study of the pressure drop by the catalyst bed requires a lengthy period and expensive experiments, however, numerical simulation by mean of Computational Fluid Dynamics (CFD) can be an alternative. In this paper, 90 wt% hydrogen peroxide solution with silver catalyst is studied in order to investigate the influence of porosity to the performances of the thruster, and to find the optimum porosity of the thruster. Species transport model is applied in the single-phase reaction simulation using the EDM for turbulence-chemistry interaction. Through this study, the effect of porosity towards the thruster performances represented in term of pressure drop, exit velocity, bed temperature, and thrust, and porosity of 0.4 found to be as an optimal value.

Use of CFD for pressure drop, liquid saturation and wetting predictions in trickle bed reactors for different catalyst particle shapes

The characterization of hydrodynamics in Trickle-Bed-Reactors is a complex task due to the opacity of the medium. In particular, the determination of pressure drop, liquid saturation , wetting of the catalyst surface and catalyst shape effect on these parameters is very important for optimal catalyst use and reactor operation. Measurements under industrial conditions are limited to indirect estimations, and direct measurement methods are limited to near-ambient conditions. In this context, the objective of the present article is to use Computational-Fluid-Dynamics to investigate pressure drop, liquid saturation and wetting efficiency in Trickle-Bed-Reactors and to improve existing correlations, with a special focus on the catalyst shape effect and wetting prediction.The Volume-Of-Fluid approach was used to simulate two-phase flow through particle loadings of spherical, trilobe and quadrilobe-shaped particles. The numerical model was validated against literature correlations in terms of pressure drop, liquid holdup and wetting efficiency. The CFD model was then employed to explore two effects that does not reach out a consensus in existing literature, i.e effects of particle shape and gas-phase velocity on wetting efficiency. As a result, it was shown that CFD provides good predictions of pressure drop and liquid saturation for different catalyst particle shapes, the achieved deviations between CFD results and correlation estimations are below 20%. A new wetting efficiency correlation is also proposed. This new correlation is able to predict wetting efficiency with a precision of 6.99% for a wide range of liquid velocities (from 0.2 to 0.8 cm/s) and gas velocities (from 5 to 20 cm/s) and three particle shapes.

Direct evaporative cooling from wetted surfaces: Challenges for a clean air conditioning solution

AbstractEvaporative cooling has a major role to play in fighting climate change and in achieving a low‐carbon economy. As it helps to reduce energy demand for air conditioning, it is gaining attention in terms of improving energy efficiency in buildings. Evaporative cooling from wetted media can enhance water–air contact, thereby improving heat and mass transfer further and avoiding aerosols. Wetted media are commonly called evaporative cooling pads and are widely used in greenhouses, intensive livestock farming, and industrial facilities. However, a deep understanding of evaporative cooling pad performance can enhance their application to indoor occupied spaces such as residential or commercial cooling, or in hybrid air conditioning systems. Most studies analyze pad performance mainly in terms of pressure drop and saturation effectiveness. However, some studies propose alternative cooling efficiency parameters and others provide insights into key aspects such as power requirements and the coefficient of performance, water consumption, risk of water entrainment, material decay, and air quality, as well as the effect of water temperature and salinity, solar radiation, or wind speed. Existing results on these less studied performance issues are reviewed, and we identify the gaps in the literature in addition to highlighting the main challenges encountered, in an effort to guide future researchers in the field and enhance the application of direct evaporative cooling.This article is categorized under: Energy Efficiency > Systems and Infrastructure Energy Systems Analysis > Systems and Infrastructure

Comparative assessment among several channel designs with constant volume for cooling of pouch-type battery module

Liquid cooling is an effective thermal management technique in reducing the peak temperature of lithium-ion batteries. To meet the development of the battery thermal management system's compact design, a liquid-based mini channel cold plate is utilised. Although several researchers proposed numerous designs of mini channels across the cold plate, a comparative assessment among these designs is limited. Therefore, a three-dimensional numerical method is introduced to explore the laminar flow of liquid coolant in six distinct mini channel designs. This includes serpentine, U-bend, straight, pumpkin, spiral, and hexagonal designs under a constant channel volume. Their cooling ability is evaluated in terms of pressure drop, temperature variation, a non-dimensional j/f factor, average temperature, uniformity factor, and cooling performance factor for varying mass flow rate and a fixed discharge rate of 3C. Results signify that the serpentine and hexagonal geometries could significantly improve temperature homogeneity, whereas the pumpkin model maintains a lower pressure drop and pumping power. Furthermore, a detailed analysis is conducted with all the channel designs for an ambient temperature and discharge rate varying from 25 °C to 45 °C and 1C to 5C, respectively. Also, a realistic drive cycle data US06 is utilised to assess the performance of optimal design serpentine channel-based battery module for on-road driving conditions.

Numerical Prediction of Homogeneity of Gas Flow through Perforated Plates

Vanes and baffles are often used as flow distributors where uniform flow is required in the apparatus of large cross-section surface areas. As an alternative, perforated plates with a range of open area ratios are applied to produce required gas flow homogeneity. Usually, the plates with various open area ratios are combined into large panels, of which total surface area can reach hundreds of square meters for large-sized industrial apparatus. Numerical modelling of the flow through such panels can be thought of as overly complex, time-consuming, and inefficient due to numerous small open area ratios in the plates and large differences in dimensions between open area ratios and free-stream areas. For this reason, numerical models of gas flow are limited to single plates only with constant open area ratios. A new indirect modelling approach of gas flow through the perforated plates panel with structural elements and various open area ratios with application of the porous media model is proposed. A perforated plate was experimentally investigated in terms of pressure drop and velocity distribution. The data obtained were used for the validation of the numerical results, which differed from the experimental results by less than 5%. In the next step, numerical analyses were performed for plates with open area ratios in the range of 30 to 70% for gas velocities of 5 and 10 m/s. A general correlation for pressure drop as a function of open area ratio was proposed. Finally, systematic numerical studies of the flow through both perforated and porous plates including structural elements were performed. The internal resistance of the porous core was calculated by means of a developed correlation. A good agreement between results with an error lower than 15% was observed.

Influence of inlet configuration and distributor geometry on the performance of cryogenic plate-fin heat exchangers

• A three-dimensional simulation model is used to evaluate flow patterns in plate-fin heat exchangers. • Performance of different distributor geometries is evaluated in terms of pressure drop and heat transfer. • Different feasible inlet configurations of a 6-stream heat exchanger are compared to an idealized geometry. • Inlet configurations can significantly affect the performance of plate-fin heat exchangers. The influence of inlet placement and distributor geometry on the steady-state efficiency and pressure drop of cryogenic plate-fin heat exchangers (PFHEs) is studied using a three-dimensional simulation model. The simulation model employs a porous media approach to combine computational fluid dynamics with well-established correlations for heat transfer and pressure drop in fin materials. An isothermal study is conducted for comparison of six different distributor geometries. The selection of a favorable design depends on a trade-off between heat transfer and allowable pressure drop of a specific task but the presented results can serve as a guideline. Furthermore, two different configurations of a 6-stream PFHE are compared to an idealized, pseudo one-dimensional design. Both feasible designs lead to a significant increase in pressure drop and the thermal efficiency of the feasible designs differs by 5 percentage points. This highlights the necessity of considering the inlet- and distributor configuration in the design of a cryogenic PFHE.

MHD flow in liquid metal blankets: Major design issues, MHD guidelines and numerical analysis

The design of breeding blankets represents the major challenge for fusion reactor engineering because of performance requirements and severe operating conditions in terms of heat load and neutron flux. Liquid metal alloys such as lead-lithium, due to their lithium content, can be used to breed tritium, one of the plasma fuel components, and owing to their high thermal conductivity, they may serve as coolants. On the other hand, there are technical issues related to the fact that the liquid metals are electrically conducting and interact with the plasma-confining magnetic field. Induced electric currents and generated electromagnetic forces affect velocity and pressure distribution in the blankets. Magnetohydrodynamic (MHD) flows for fusion applications have been often investigated in simplified geometries, such as pipes, ducts, bends, with focus on their fundamental features. These analyses are essential, since results remain valid as background for the development of blanket designs, even when a concept is dismissed. However, the conceptual study of fusion blankets requires to take into account the global multiple effects, that arise when the full system is considered. Progress made in fusion-related MHD research results from combined numerical and experimental activities. In this paper we review and summarize features of 2D and 3D MHD flows that are typical in liquid metal blankets, together with available correlations for MHD pressure losses. This knowledge can provide simple design MHD guidelines that support a preliminary estimate of MHD effects in a blanket concept, in terms of pressure drop and flow distribution.

Numerical Analysis of the Effects of the Structure Shape and Orientation of Kelvin Cell Porous Structures during Air Forced Convection

In recent years, in order to counteract the growth of environmental pollution and the contemporary scarcity of various energy sources, researchers have proposed innovative and efficient solutions for heat transfer applications. Extended surfaces, which can involve the use of fins, open cell metal foams, etc., have been demonstrated to be promising solutions. Open cell metal foams consist of structs intersecting at nodes resulting in stochastic oriented cells. Periodic metal foams have also attracted great interest. These structures are made of a single cell unit periodically replicated. Kelvin cells and Weaire–Phelan ones are two conventional elementary unit cells. In this paper, a numerical model is developed and validated, aiming at analysing the thermal and hydraulic behaviors of modified Kelvin cell-based metal foams during air forced convection. Constant porosity (0.9) and pore density (40 PPI) were adopted. Five different geometrical configurations (one cylindrical and four elliptical) and four orientations (0–15–30–45°) of the struts with respect to the main air flow direction were investigated. The inlet air velocities varied between 0.5 and 4 m s−1. Interesting results were obtained and discussed in terms of pressure drops, heat transfer coefficients, and pumping power per area density.