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In this work, a thermal behaviour comparison of a new bamboo-based and banana-based Green Bio-Composites (GBC) is conducted using thermogravimetric analysis (TGA) and cone-calorimeter experiments. An Intumescent Fire-Retardant (IFR) coating (a mixture of Exolit IFR36 and boric acid) has been applied on the investigated GBC materials in order to explore the flammability resistance of such GBCs. Vacuum Bag Resin Transfer Moulding (VBRTM) technique has been used to manufacture the samples. TGA test have been conducted under oxidative atmosphere with three different heating rates while cone calorimeter tests have been performed with a horizontally exposure on the top surface of the sample. The outcomes of TGA revealed that Bamboo-based (BM-GBC) and Banana-based (Bn-GBC) materials exhibited similar thermal degradation patterns. However, BM-GBC outperformed Bn-based in the cone calorimetry analysis, this is proven by the fire reaction parameters as well as the higher char residue. In addition, IFR coating improved the flame retardancy of both GBCs, reduced the Peak Heat Release Rate (PHRR) by approximately 40–50% and smoke production (SEA) by 26%. SEM and EDS analysis of char residue were performed to deeply investigate the effectiveness of the IFR as a protecting layer. [ABSTRACT FROM AUTHOR]

Estimating the oil-water temperatures in flowlines is challenging especially in deepwater and ultradeepwater offshore applications where issues of flow assurance and dramatic heat transfer are likely to occur due to the temperature difference between the fluids and the surroundings. Heat transfer analysis is very important for the prediction and prevention of deposits in oil and water flowlines, which could impede the flow and give rise to huge financial losses. Therefore, a 3D mathematical model of oilwater Newtonian flow under non-isothermal conditions is established to explore the complex mechanisms of the two-phase oil-water transportation and heat transfer in different flowline inclinations. In this work, a non-isothermal two-phase flow model is first modified and then implemented in the InterFoam solver by introducing the energy equation using OpenFOAM® code. The Low Reynolds Number (LRN) k-e turbulence model is utilized to resolve the turbulence phenomena within the oil and water mixtures. The flow patterns and the local heat transfer coefficients (HTC) for two-phase oil-water flow at different flowlines inclinations (0°, þ4°, þ7°) are validated by the experimental literature results and the relative errors are also compared. Global sensitivity analysis is then conducted to determine the effect of the different parameters on the performance of the produced two-phase hydrocarbon systems for effective subsea fluid transportation. Thereafter, HTC and flow patterns for oil-water flows at downward inclinations of 4°, and 7° can be predicted by the models. The velocity distribution, pressure gradient, liquid holdup, and temperature variation at the flowline cross-sections are simulated and analyzed in detail. Consequently, the numerical model can be generally applied to compute the global properties of the fluid and other operating parameters that are beneficial in the management of twophase oil-water transportation. [ABSTRACT FROM AUTHOR]

Two‐phase flow in pipes finds application in many industrial activities, mostly in the energy sector, necessitating model systems that correctly predict flow behaviors like flow pattern, pressure drop, and liquid holdup during the design and planning of a fluid transport system. This study aims to analyze three‐dimensional two‐phase liquid‐gas flows in a horizontal flowline. InterFoam, a transient two‐phase solver, was first modified to implement the low‐Reynolds number (LRN) k‐ε model in the OpenFOAM source code. This LRN k‐ε turbulence model is utilized to resolve the turbulence phenomena within the two‐phase mixtures. The two‐phase flow is calculated by using the developed solver based on the volume‐of‐fluid approach. Flow pattern results at different superficial gas and liquid velocities are validated by experimental data from the literature. Then, three Reynolds‐averaged Navier‐Stokes models were used for computations: LRN k‐ε, standard k‐ε, and the shear stress transport k‐ω model. [ABSTRACT FROM AUTHOR]

In this paper, we explore the improvement of the aerodynamic characteristics of wind turbine blades under stall conditions using passive flow control with slots. The National Renewable Energy Laboratory (NREL) Phase II rotor, for which detailed simulations and experimental data are available, served as a baseline for assessing the flow control system effects. The position and configuration of the slot used as a flow control system were determined using CFD analysis. The 3D-RANS equations are solved with ANSYS FLUENT using the k-ω SST turbulence closure model. The pressure coefficient for different wind speeds for the baseline configuration is compared to the available experimental data. The comparison shows that CFD results were better for the attached flow. The current work consists of a 3-D CFD modeling of a rotating blade equipped with different flow control systems: single-slot (S-S) and two-slots (T-S). The computation provides a better understanding of the influence of these flow control devices on the performance of wind turbine blades, the control of boundary layer separation, and the rotation effect. These control systems increase the power output by over 60% at high wind speeds with large separated boundary layer regions. For the configuration with the control system, the slot has shown its ability to delay the boundary layer separation. However, the improved aerodynamic performance has been proven for medium and high angles of attack where the flow is generally in the stall condition. The addition of the second slot changed the flow behavior, and an improvement was observed compared to the single slot configuration. The results are helpful for the design and development of a new generation of wind turbine blades. [ABSTRACT FROM AUTHOR]

Summary: In this research, an evaluation of the performance improvement of a new reactor configuration for steam methane reforming (SMR) is carried out through a numerical‐experimental approach. Two configurations of M‐PCR have been studied numerically to compare the benefits. The first one consists of a conventional micro planar cell reactor (noted clear M‐PCR), which is impregnated in its central axis in the direction of gas mixture flow by Ni/Al2O3 catalyst. The second M‐PCR configuration is equipped with nickel‐based metal foam (MF) (noted M‐PCR MF), which supports similar catalyst layer as for clear M‐PCR configuration. The same operating conditions and catalyst weight density are set. 2D numerical solution of the transport equations was performed with a homemade code based on FORTRAN language to explore the heat and mass transfer during the SMR process. To better evaluate the nickel‐based MF effects, permeability coefficients, that is, Darcy and inertial coefficients, were first measured using an experimental bench for hydrodynamic characterization of porous media. Comparison has showed that M‐PCR MF configuration provides a significant enhancement in terms of hydrogen yield (73,25%). Furthermore, the catalyst layer length could be reduced by four times compared to conventional M‐PCR due to MF implementation, leading to important economic improvement while keeping an interesting SMR efficiency. [ABSTRACT FROM AUTHOR]

Compact heat exchangers for heat removal has become one of the most effective cooling techniques. In this paper, numerical scheme to simulate conjugated heat transfer using additively manufactured heat exchanger is presented. A lattice structure as porous medium is used as effective cooling techniques for heat removal. The objective of these lattices is to transmit heat from the hot part to the cold part while letting the system benefit from two phenomena, heat conduction and convection. An optimization procedure using response surface method is proposed for the presented compact heat exchanger to improve the efficiency. This method was introduced in order to reach the global optimum with a limited number of computer experiments. Two optimization variables are identified: edge thickness for the lattices and the inlet velocity. A constraint optimization problem is formulated to maximize the heat flux through the heat exchanger. Hence at the same time, limiting the increase of the pressure drop and the decrease of the exit temperature. [ABSTRACT FROM AUTHOR]

The present work deals with the development of new metal-based nanocomposites reinforced by multiwall carbon nanotubes (MWCNTs) for nanotechnology field. Samples are prepared in situ and contain a ratio of 4:1 Fe–Cu, with MWCNT additions of 0 vol%, 0.25 vol%, 0.75 vol% and 1 vol%, respectively. The materials are characterized using thermodynamic and structural techniques like dilatometry, DSC, TG, X-ray diffraction and Raman spectrometry (SERS). Dependence of relative variations in elongation has been noted as a function of the temperature range. Among the synthesized materials, the FeCu1%MWCNT nanocomposite seems to be the best configuration. The latter expands the least and presents fewer defects. The Raman study of the FeCu1%MWCNT nanocomposite showed that the MWCNT are in an ordered state. The addition of 1% of MWCNT to FeCu matrix gives the most refined structure with high thermal stability and provides better FeCu ion protection against oxidation. [ABSTRACT FROM AUTHOR]

A simple and rapid method for synthesizing new ternary nanocomposites based on Mg, Zn, and Co has been developed using ultrasound technology. The nanocomposites were characterized using structural, optical, and thermal methods. XRD diffraction confirmed the formation of different crystalline nanocomposite phases (MgO, ZnO, and Co3O4) and binary phase (Mg–Zn), while Raman spectroscopy and FTIR, identified the vibration modes and provided information on functional groups and chemical bands present in samples. SEM showed the octahedron-shaped nanoparticles morphology with different averages size for the nanocomposites oxide prepared. Photoluminescence analysis showed the presence of green, blue, and ultraviolet emissions, with green luminescence bands being most often observed. Heat capacity and thermal diffusivity measurements were used to study thermal properties. • New ternary nanocomposites based on Mg, Zn, and Co were synthesized using sonochimical method. • Thermo-structural characterization showed favorable properties for hydrogen storage. • Higher thermal diffusivity and heat capacity were noticed for samples with high Mg and Co content. • Nanocomposites with balanced Mg and Co content are very promising for solid-state hydrogen storage. [ABSTRACT FROM AUTHOR]

Wall-coated Methane Steam Reformers (MSR) are commonly used as fuel processing in the hydrogen production chain. In such devices, the catalyst which is generally nickel-based is coated on the walls, and the heat supply influences directly the fuel processing efficiency. In this work, two-dimensional CFD study is carried out to explore an enhancement on MSR thermal behavior. Two configurations in terms of catalyst coating are investigated. The first MSR configuration is equipped with continuous catalytic layer, while in the second, discrete catalyst layers separated by an inert gap are imposed. The effect of the catalyst patterning on the thermal and mass behavior of MSR is discussed. The results show that the MSR efficiency can be improved by extending the catalytic zone and discretizing the catalyst coating. Comparing to conventional MSR with continuous catalytic layers, enhancement of 28.71% in CH 4 conversion and 88.574% in H 2 production is realized by using discretized catalytic layers. • 2D numerical modelling of plate steam methane reformer designed for H 2 production. • Comprison between two steam reformer designs : methane conversion and hydrogen production evaluation. • Improved catalyst deposition in the reactor walls leads to superior thermal performances. • The reformer efficiency can be improved by segmenting the catalytic zone into subzones. • Enhancement of 28.71% in CH 4 conversion and 88.574 % in H 2 production is achieved. [ABSTRACT FROM AUTHOR]

Highlights • Numerical analysis on the effect of the catalyst coating design in plate reactors. • Better CH 4 conversion when the catalytic zone of the reactor is longer. • Discretizing and alternating catalytic layers give the best performances. • Inert surfaces among catalytic layers improve the thermal performances. • Good thermal performances act positively on the H 2 production. Abstract In this research, the performance evaluation of methane (CH 4) steam reforming in Wall Steam-methane Reformer (WCR), intended to supply hydrogen (H 2) to SOFC, is investigated using homemade code based on 2D numerical modeling. Focus is on the design of the catalyst coating on the walls of reactor. Various designs of nickel-based catalyst coating were closely examined and compared purporting to understand their effect on the WCR efficiency. The WCR designs operate at similar industrial operating conditions and with the same catalyst density. The computations were discussed with respect to the possible improvement on WCR efficiency. Comparing to the worst catalyst design found, the CH 4 conversion rate improving is estimated to 31%, which corresponds to 95.8% more in H 2 production. The obtained results are of practical importance for the design of the catalyst coating and saving fuel energy. [ABSTRACT FROM AUTHOR]

Numerical modeling of a heated mixture of methane with steam in 2D plane Wall-Coated Steam Methane Reformer (WC-SMR) with surface catalytic reaction at industrial conditions has been performed. The modeling was performed within the framework of Navier-Stokes equations for a laminar flow of a multi-component compressible gas. The influence of the insertion of non-catalytic nickel-based metal foam matrices in the catalytic zone of the WC-SMR on the hydrodynamic, thermal and mass behaviors of the gas mixture and its distribution along the reactor have been investigated. Three different Metal Foam (MF) samples have been investigated and then compared: Ni-Foam, Ni-Cr-Foam and Ni-Fe-Cr-Foam. It has been shown that not only the use of metal foam matrices but also their thermo-physical properties are important to improving the WC-SMR efficiency. It is demonstrated that such material can bring a significant enhancement for hydrogen production, heat and mass transfer processes. 16.91% of improvement in terms of H 2 production is realized. [ABSTRACT FROM AUTHOR]

Due to the endothermic nature of the steam methane reforming reaction, the process is often limited by the heat transfer behavior in the reactors. Poor thermal behavior sometimes leads to slow reaction kinetics, which is characterized by the presence of cold spots in the catalytic zones. Within this framework, the present work consists on a numerical investigation, in conjunction with an experimental one, on the one-dimensional heat transfer phenomenon during the heat supply of a catalytic-wall reactor, which is designed for hydrogen production. The studied reactor is inserted in an electric furnace where the heat requirement of the endothermic reaction is supplied by electric heating system. During the heat supply, an unknown heat flux density, received by the reactive flow, is estimated using inverse methods. In the basis of the catalytic-wall reactor model, an experimental setup is engineered in situ to measure the temperature distribution. Then after, the measurements are injected in the numerical heat flux estimation procedure, which is based on the Function Specification Method (FSM). The measured and estimated temperatures are confronted and the heat flux density which crosses the reactor wall is determined. [ABSTRACT FROM AUTHOR]

This paper deals with a numerical study on the steam methane reforming reaction performances into a wall-coated steam methane reformer (WC-SMR), intended to produce hydrogen. In this work a new catalytic pattern, purporting to enhance the WC-SMR efficiency, is proposed. A comparison study is made between the new inter-catalytic layers pattern and a conventional one with a continuous catalytic layer pattern. Both WC-SMR models operate at similar conditions and at the same design parameters, except the catalytic zone length which is monitored by taking into account the inter-catalytic layers spacing or not. Our results show that, by adopting a catalytic surface with an inter-catalytic spacing, the methane conversion could be enhanced and thus the hydrogen production is intensified. [ABSTRACT FROM AUTHOR]

In this paper, a numerical simulation of improving performances of catalyst wall-coated steam methane reformer for hydrogen production is presented. A comparative analysis of three different configurations of a parallel-plate reformer is carried out. A single catalyst layer of 10 mm length is adopted for the first configuration, while, for the second one, it is divided into five discrete uniform layers and impregnated alternately on the reformer's walls. For the third one, metal foam bounded by the discrete catalyst layers is inserted into the catalyst region. The effects of the catalyst-layer patterns and the metal foam insertion on the thermal behavior and the reaction kinetics are analyzed. The involved transport phenomena are governed by momentum, energy and species equations. The Darcy-Brinkman-Forchheimer model is used in the metal foam region while the Navier–Stokes equations are employed in the clear region. The obtained results show that this combination between the catalyst arrangement and the metal foam insertion, improves the steam methane reformer efficiency. The CH 4 conversion rate improving is estimated to 44.6%. [ABSTRACT FROM AUTHOR]

The enormous cost of handling the challenges of flow assurance in subsea wells, flowlines, and risers, especially in deepwater applications, has necessitated a proactive approach to prevent their risk of occurrence. To ensure that transportation of the hydrocarbon is economical and efficient from the subsea wellhead to the processing units, a flow assurance heat management system is relevant in the design and planning of a fluid transport system. Consequently, the advancement of new technologies to serve the increasing need by exploring the technologically challenging and hostile subsea fields is of great importance. A comparative study on heat management systems in flowlines was conducted from the top five publishers (Elsevier, Springer, Taylor & Francis, Wiley, and Sage) based on the number of publications to determine the level of work done by researchers in the last decade, the figures from the study showed the need for scientific research in the field of active heating. Additionally, a review was implemented to ascertain the likely advantages and drawbacks of each technique, its limitations concerning field applications and then recommend suitable cost-effective technique(s). The active heating system gives the most cost-effective solution for subsea deepwater fields. [ABSTRACT FROM AUTHOR]

This study focuses on enhancing weld joints of AA2017 aluminum alloys obtained through the UFSW (underwater friction stir welding) process. An integrated method utilizing grey relational entropy measurement as a multi-response optimization tool was employed. The objective was to improve the performance of the weld joint by optimizing the process parameters, including advanced speed, tool rotation speed, and forging force, to enhance tensile strength, elongation, and microhardness. The L9 orthogonal design with three factors and three levels was utilized, and subsequent analysis of variance and confirmation tests were conducted. Furthermore, the influence of lateral deviation of the welding tool on the mechanical properties and microstructural characteristics of the optimal joint was investigated. Experimental results aligned well with the outcomes predicted by the proposed mathematical model, affirming the effectiveness of the optimization method. Notably, the study demonstrated an increase in weld joint efficiency from 68.55 to 93% through the implementation of the optimization approach. The welding tool deviation ranging from − 1.5 to 1.5 mm showed that the tensile strength of the optimal joint decreases while the strain rate increases when the offset was on the advancing side (AS). [ABSTRACT FROM AUTHOR]