Hydrothermal Characteristics Research Articles

RETRACTED: Mixed convective heat transfer in a power-law fluid in a square enclosure: Higher order finite element solutions

Incorporation of momentum gradients produced due to inertial motion of the lid along with the presence of temperature differences in the configuration make the physical problem more significant. The joint variation of momentum and thermal diffusion in diversified natural liquids is recognized as mixed convection. Valuable attention has been received by such a phenomenon in different areas of science and technology such as in wind current–based solar receivers, electronic instruments, control of emergency shutdown in reactors, thermal exchangers, oceanic currents, control of atmospheric pollution, and so on. So, the main focus is to contemplate hydrothermal characteristics of a power-law fluid contained in a square cavity with the movement of the upper lid and being thermally adiabatic. The other extremities are considered to be at rest, and the base wall is prescribed with uniform/non-uniform temperature distributions. The governing formulation of the problem is handled by executing a finite element approach. Hybrid meshing is performed for domain discretization, and weak variational formulation is utilized for formulation discretization. Second-degree polynomials are employed as the interpolation function, providing information about velocity and temperature distributions at boundary and intermediate nodes. The system of finalized non-linear equations is resolved by using the Paradiso software. The results for velocity and temperature distributions are attained comparatively for uniformly and non-uniformly heated profiles. The kinetic energy and average Nusselt number are also computed against flow concerning variables. From the attained graphical and tabular data, it is deduced that by increasing the Reynolds number, inertial forces dominate over buoyancy forces and the effect of lid movement is prominent on flow characteristics. It is also inferred that for the shear thickening case and for all values of the Reynolds number, the average Nusselt number shows a constant behavior.

MAGNETOHYDRODYNAMIC FLOW AND HEAT TRANSFER THROUGH A CIRCULAR TUBE FILLED WITH HOMOGENEOUS AND HETEROGENEOUS POROUS MEDIUM

In this paper, we study the laminar steady flow of incompressible viscous magnetohydrodynamic (MHD) fluid inside a circular tube filled with homogeneous/heterogeneous porous medium. A transverse uniform/nonuniform magnetic field is applied, along with a uniform heat flux boundary condition. The Brinkman equation is used to model the flow through the saturated porous medium. Exact solutions of velocity and temperature fields, friction factor, and Nusselt number (<i>Nu</i>) in terms of the shape parameter (σ) and Hartmann number (<i>M</i>) are presented. In the limit of the zero shape parameter and the absence of magnetic field, the Brinkman model results converge to the Hagen-Poiseuille flow solution of circular pipe flow. In the opposite limit of the infinite shape parameter and the absence of magnetic field, the solutions approach the Darcy model results. In terms of the hydro-thermal characteristics of the flow, the Poiseuille flow results and the Darcy model results are shown to serve as the lower and upper bounds, respectively. A significant increase in the heat transfer in heterogeneous porous medium with the nonuniform magnetic field (highest <i>Nu</i> = 12) compared to homogeneous porous medium with uniform magnetic field is identified (highest <i>Nu</i> = 8). We also validate the results of homogeneous and heterogeneous porous medium with uniform/nonuniform magnetic field using numerical solutions.

Investigation of novel turbulator with and without twisted configuration under turbulent forced convection of a CuO/water nanofluid flow inside a parabolic trough solar collector

<abstract> <p>In this study, we numerically investigated the hydrothermal performance of a parabolic trough solar collector system in which nanofluids are used to transfer thermal energy. The single-phase model has been used to evaluate the respective influences of the spherical shape of nanoparticles with a volume fraction of (φ = 3%), Reynolds number varying between 50,000 ≤ Re ≤ 250,000 and the insertion of a turbulator with and without a twisted configuration on the hydrothermal characteristics created by the turbulent forced convection of a CuO/water nanofluid. The shaped turbulator (+) inserted in the absorber tube had a length turb_L = 2.4 m, a height turb_H = 40 mm and a width turb_t = 2 mm. In the second configuration, the considered turbulator was twisted (N_twist = 5, 10 and 15 twists). The turbulator was positioned at 0.6 m from the inlet of the tube and 1 m from the outlet of the collector. The studied performances included the heat transfer characteristics, pressure drop, friction factor, thermal efficiency, temperature and velocity distribution of the outlet field. The most significant contribution of this study is the proposal of the best parameters to increase the thermal and hydraulic efficiency of parabolic troughs by adding a new turbulator with the considered twists.</p> </abstract>

Catalytic hydrolysis of corncob for production of furfural and cellulose-rich solids: Product characterization and analysis

Experiments were carried out to investigate cellulose and furfural from catalytic hydrolysis of corncob. This process improved the comprehensive utilization of hemicellulose and cellulose in biomass resources. Influence of factors (temperature, reaction time, concentration of catalysts, liquid to solid ratio (LSR)) on hydrothermal characteristics, furfural yield, properties and retention of cellulose were investigated through orthogonal and parameter tests. Acetic acid (6 wt%) and FeCl3 (40 mM) achieved the highest furfural yield (47.60%) and relatively high cellulose retention ratio (71.84%) at 180 °C, 45 min, and 3 mL/g of LSR. While AlCl3 and citric acid obtained low furfural yield and the lowest cellulose retention ratio (8.38%). Furfural was dominant in distillated organics (GC-MS areas ≥97.9%), by contrast furfural, 5-hydroxymethyfurfural and vanillin were main organics in residual liquors. The peak of furfural yield switched to shorter reaction time as temperature increased. Combination of AlCl3 with acetic acid and citric acid accelerated cellulose degradation. NaCl inhibited furfural yield and promoted lignin decomposition. Higher temperature and greater concentration of FeCl3 contributed to reduced crystallinity of cellulose during hydrothermal treatment.

Optimization of ridge–furrow mulching ratio enhances precipitation collection before silking to improve maize yield in a semi–arid region

Insufficient soil moisture and heat often limit crop productivity in semiarid regions. The effects of the ridge–furrow mulching system (RFMS) on improving the soil water and temperature conditions have been confirmed in many studies, but the effects of different ridge–furrow ratios on the changes in soil water, temperature, and the interception rate of canopy photosynthetically active radiation (PARIR), and thus crop productivity remain unclear. Therefore, we conducted a field experiment from 2015 to 2020 in the Loess Plateau region of northwest China by testing conventional tillage without mulch (CK) as a control treatment and three ridge–furrow ratios (60:60 cm, 80:40 cm, and 50:10 cm). We studied the changes in the soil hydrothermal characteristics and the response of maize canopy under continuous mulching with different ridge–furrow ratios. Compared with CK, RFMS increased the soil water storage in the 0–200 cm soil layer by 5.2–9.3% and the effective accumulated soil temperature by 10.4–29.1%. The hydrothermal properties affected the maize canopy under RFMS where compared with CK, PARIR increased by 6.3–11.7% at 61 to 90 days after planting (DAP) and the maize yield finally increased by 44.8–77.9%. Correlation analysis showed that the contribution of precipitation from 0 to 90 DAP to the maize yield was greater than that of the effective accumulated soil temperature, whereas the contribution of the effective accumulated soil temperature was greater at 91 to 150 DAP. The precipitation during 61 to 90 DAP was the most important factor that affected the yield during the whole growth period. Thus, increasing the ridge–furrow ratio can improve the soil hydrothermal properties and maize productivity to ensure food security and avoid resource shortages in the Loess Plateau region and similar areas.

RETRACTED: Measure and evaluate the hydrothermal flow of a Newtonian fluid in homogeneous permeable media equipped with a fin: A numerical approach

This study envisions the hydrothermal characteristics of a viscous fluid in a homogenously permeable hexagonal enclosure. Permeability aspects in the flow domain are described by employing the Brinkman-extended Darcy law. A corrugated hexagonal enclosure along with the placement of a star-shaped fin is taken into account. Heated rectangular blocks at horizontal extremities are installed, and sliding sides of the enclosure are considered to be cold to provide convective potential to the flow. In addition, adjoining portions of the heated rectangular blocks are supposed to be adiabatic. The dimensionless governing equations of the resultant problem are derived initially and then solved numerically by implementing the Galerkin finite element approach, and COMSOL is obliged. For this purpose, first, domain discretization is demonstrated in view of 2D elements by performing hybridized meshing. Then, the system of non-linear equations is resolved by a non-linear solver (PARADISO). The grid convergence test is performed to confirm the credibility of the carried out simulations by calculating the average Nusselt number at different refinement levels. A change in associated distributions against the involved physical parameters (Darcy number (Da), Rayleigh number (Ra), and Prandtl number (Pr)) for a wide range is revealed through graphs and tables. Quantities like kinetic energy and heat flux (local and average) are also evaluated through concerned parameters. The results clearly demonstrate that the Darcy number tends to reduce the heat transfer rate. In particular, it is depicted that by increasing the Rayleigh number (Ra), strengthening in the temperature potential arises in the system, thereby magnifying the heat transfer rate. Moreover, it is disclosed that by reducing the Darcy number, kinetic energy shows a decreasing trend.

Effect of Dimpled Rib with Arc Pattern on Hydrothermal Characteristics of Al2O3-H2O Nanofluid Flow in a Square Duct

The present work is concerned with the experimental analysis of the thermal and hydraulic performance of Al2O3−H2O nanofluid flow in dimpled rib with arc pattern in a square duct. The Alumina nanofluid consists of nanoparticles having a size of 30 nm. Reynolds number Renum studied in the square duct range from 5000 to 26,000. The nanoparticle volume fraction (ϕnp) ranges from 1.5% to 4.5%, the ratio of dimpled-arc-rib-height to print-diameter HAD/Pd ranges from 0.533 to 1.133, the ratio of the dimpled-rib-pitch to rib height PAD/HAD range from 3.71 to 6.71 and dimpled arc angle (αAD) range from 35° to 65°. The Al2O3−H2O-based nanofluid flow values of Nusselt number Nurs and friction factor frs are higher in comparison to pure water. The dimpled ribs in the arc pattern significantly improved the thermal-hydraulic performance of the investigated test section. The nanoparticle concentration of 4.5%, the ratio of dimpled arc rib height to print diameter of 0.933, the relative dimpled arc rib height of 4.64 and the dimpled arc angle of 55° deliver the maximum magnitude of the heat transfer rate. The maximum value of the thermal-hydraulic performance parameters was found to be 1.23 for Al2O3−H2O-based nanofluid flow in a dimpled rib with arc pattern square duct for the range of parameters investigated. Correlations of Nurs, frs and ηrs have been developed for the selected range of operating and geometric parameters.

Analysis of SWCNT-water nanofluid flow in wavy channel under turbulent pulsating conditions: Investigation of homogeneous and discrete phase models

Improving thermal performance in heated channels has received much attention from many researchers due to its presence in various thermal systems. The present research numerically illustrated the effect of turbulent pulsating flow and SWCNT-water nanofluids in sinusoidal wavy channel on hydrothermal characteristics and entropy production. This study aims to provide a new thermal management approach for compact heat exchangers. Two various models for describing the motion of nanoparticles in a base fluid are applied. These models are Homogeneous single-phase, SPM and Lagrangian-Eulerian model (or discrete phase model), DPM. Governing equations are computationally solved utilizing the finite volume technique. This simulation covers Reynolds number, pulsation frequency, phase shift and nanoparticles concentration in the range of (4000 ≤ Re ≤ 7000), (1 ≤ f ≤ 5), (0° ≤ θ ≤ 180°) and (0% ≤ φ ≤ 3%), respectively. CFD simulations show that the pulsation frequency, f and phase shift, θ have a significant role in improving the heat transfer ratio and controlling the entropy generation through the wavy channel. Finally, it is recommended to use SWCNT/water nanofluid with a high-volume fraction (φ = 3%) as a working fluid in the considered channel due to its high heat transfer ratio and low thermal irreversibility.

A comparative numerical analysis and environment assessment to examine hydrothermal behavior of two serpentine heatsink with water/silver Nano fluid applying two-phase mixture model

In the present study, the hydrothermal characteristics of two different a) serpentine (Conf. A), and b) double serpentine (Conf. B) heatsinks with water/silver Nano Fluid (NF) were studied. To this end, the Finite volume method was performed, and the governing equations were discretized based on the second upwind approach and solved numerically applying the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) scheme. The results demonstrated that the thermal resistance (R) of Conf. A is lower than that of Conf. B at low Re numbers, and these two configurations have an identical R as Re increases to 2000. Also, the convective heat transfer in Conf. A is slightly higher than that in Conf. B and for Re=2000 both configurations have a same h value. Moreover, the increasing of nanoparticle concentration from 0% to 1% increases h by 12.55% and decreases the pressure drop (ΔP) by 4.25%. In addition, the CPU mean temperature of Conf. A is 0.8% and 0.1% lower than that of Conf. B for Res of 500 and 2000, respectively. On the other hand, ΔP in Conf. A is 74% higher than that in Conf. B. Besides, Conf. B exhibits a better temperature uniformity as compared to other configuration. The parameter of figure of merit was obtained as 1.47 to 1.52 at Res of 500 and 2000, respectively, which showed that Conf. B provides a higher hydrothermal performance over the other configuration.The environmental impact of the designed heat sink is equal to 0.5388.

The parametric optimization to enhance the pin-fin microchannel heatsink performance using splitter and water/silver nanofluid applying the two phase mixture model

The present study deals with the 3-D numerical analysis of hydrothermal characteristics of a pin-fin heatsink with splitter using two-phase mixture model. A parametric optimization was performed considering different Re numbers (500-2000) and nanoparticle concentrations (φ=0-1%) to determine the optimum operating conditions of the system yielding the highest heat transfer coefficient (h) and lowest pumping power (W˙p). The outcomes showed that in the pin-fin heatsink with splitter, h (or W˙p) increases by 2.8-7.8% (or 5.5%), 5.6-7.9%% (or 11.27%), and 5.9-6.6% (or 14.80%) for Re numbers of 1000, 1500, and 2000, respectively, over the other case without splitter. The enhancement in the h is obtained due to increasing the heat transfer surface area and better flow mixing that caused by using the splitters. The pressure drop, however, escalates due to increasing the contact surface area of the NF and the solid parts as well as mixing the vortexes formed around the pin-fins. In addition, mean CPU temperature for the case of splitter pin-fin heatsink is 0.52-0.79%, 0.45-0.65%, and 0.47-0.50% lower than that for the heatsink without splitter at Re numbers of 1000, 1500, and 2000, respectively. The figure of merit (FOM) was obtained as 1.06-1.16 indicating a better hydrothermal performance of the splitter heatsink as compared to the other case.

Heat transfer intensification of turbulent forced convection by inserting discontinuous twisted tapes in a wavy tube; hydrothermal and thermodynamics analysis

The current study presents a numerical investigation on turbulent hydrothermal characteristics in a wavy passage equipped with discontinuous twisted tapes. The working fluid is water and passage walls are kept under constant wall temperature. The effect of Reynolds number (Re = 2500, 4500, 6500, 8500 and 10500), twist angle (TA = 90∘ and 180∘) and inclination angle (IA = 15∘ and 30∘) on velocity fields and streamlines, temperature contours, Nusselt number, friction factor, turbulent kinetic energy (TKE), thermal performance factor (TPF), energy efficiency factor (EEF) and entropy generation rate are evaluated. More uniform temperature and velocity fields can be found as both wavy passage and twisted tape are simultaneously applied. Both heat transfer rate and pumping power rise with increasing Reynolds number, twist and inclination angles. Results reveal that the twisted tape play more remarkable role on Nusselt number and friction factor at lower inclination angle. The best value of EEF is detected 24.6% occurring for passage with IA = 15∘ and TA = 180∘ at Re = 2500. Among all considered cases, those of empty wavy passage with IA = 30∘ at Re = 8500 and 10500 provides negative values of EEF, referring to inefficient cases from energy viewpoint. The contribution of wavy passage and twisted tape on heat transfer enhancement is individually assessed and it is found that the best value of twisted tape involvement on enhanced heat transfer is 79.6% taking place for configuration with IA = 15∘ and TA = 180∘ at Re = 4500. Finally, based on CFD results, passages are examined from thermodynamics viewpoint and it is shown that the second law efficiency growths with increasing twist and inclination angles.

Hydrothermal behavior of hybrid magnetite nanofluid flowing in a pipe under bi-directional magnetic field with different wave types

• Convection of Fe 3 O 4 /water nanofluid flow experimentally investigated. • Constant and alternating magnetic field effects are considered. • Sinus, square, and triangle waves were used for alternating magnetic field wave type. • Square wave is the best option to obtain higher Nusselt numbers for Fe 3 O 4 /water nanofluid flow. • Lower frequencies offer better enhancement. This experiment setup has been developed to elucidate the effect of different wave types (sinusoidal, triangle, square) of bi-directional magnetic field on hydrothermal characteristics of hybrid magnetite nanofluid flowing through a tube. The bi-directional magnetic field is not a novel method among active methods of heat transfer enhancements, yet the effects of different wave types have not been researched so far. In this study, the effects of different wave types of alternating magnetic fields with various frequencies ( f ) (2, 5, and 15 Hz) on flow and heat transfer characteristics of Fe 3 O 4 -Cu/Water hybrid magnetic nanofluid flow have been investigated experimentally. The major findings have been discussed for different combinations of hybrid magnetite nanofluid, types of waves, values of Reynolds number ( Re ), and f . The hydrothermal characteristics and their effects on usability in the industry with high efficiency have been established in terms of average Nusselt number ( Nu ), average friction factor (f), and Performance Evaluation Criteria ( PEC ). It is concluded that the use of triangle wave type with f = 15 Hz with 2% Fe 3 O 4 /water shows the highest enhancement in f by 500% compared to distilled water ( DW ) at Re = 994 while the use of square wave type with f = 5 Hz using the same Re and nanofluid presents the highest increase in Nu by 15.3% compared with DW. Above all, the triangular wave type is determined as an optimum wave type for f = 15 Hz while the sinus and square wave types are realized as optimum ones for f = 5 Hz .

Field Investigation on Thermal Regime of Permafrost and Talik in a River Terrace, the Interior of Qinghai-Tibet Plateau

To carry out engineering construction in a permafrost area, it is of great importance to grasp the spatial distribution of permafrost and its hydrothermal characteristics within the scope of engineering activities. Compared with the continuous permafrost area, the permafrost distribution in discontinuous permafrost area is complicated due to existence of island talik, which causes highly poor continuity and uniformity of ground hydrothermal conditions and brings great difficulty and uncertainty to the engineering geological investigation. In the present study, the spatial distribution of permafrost and the freeze-thaw process of shallow ground at the I-stage terrace of a river on the Qinghai-Tibet Plateau were studied based on field investigation including drilling, electrical resistivity tomography, and borehole temperature measurement. The results show that the relict permafrost, patchy permafrost, and island talik are distributed in the limited range of the study area. Among them, the buried depth of relict permafrost layer is in the range of 7 ~ 14 m, while the patchy permafrost layer is in the range of 3.0 ~ 17.0 m depth, and the mean annual ground temperature of both is close to -0.1°C, which belongs to extremely high-temperature permafrost. The seasonal freezing/thawing depths of shallow ground within the relict permafrost, patchy permafrost, and island talik range from 2.5 to 3.0 m. The freezing period of the seasonal freezing layer is 5.5 months, while the thawing period of the seasonal thawing layer is 6 months. The complex plane and spatial distribution of permafrost in the field are closely related to local factors such as topography, geomorphology, groundwater, and lithology of shallow ground. It is believed that the formation of the island talik in the study area is controlled by solar radiation and precipitation infiltration.

Trace elements geochemistry, total organic carbon, palaeosalinity, and hydrothermal characteristics of the Cretaceous black shale in the Mamfe Basin (West Africa)

The shales of the Mamfe basin were geochemically analyzed to determine their paleosalinity and hydrothermal characteristics which existed at the time of their deposition. Elemental ratios such as boron/gallium (B/Ga), strontium/barium (Sr/Ba), and total sulphur/total organic carbon (S/TOC) and TOC/S were applied for paleosalinity reconstruction. The shales of the Mamfe basin show B/Ga is <3, Sr/Ba <0.2, and S/TOC is <0.1 and TOC/S >6 the values of the elemental ratio show that the Mamfe shales were deposited in a freshwater environment. For hydrothermal activities ratio, Sc/Cr was used and Binary diagrams TOC vs P and Co/Zn vs TOC were constructed to discriminate between normal water, mixed and hydrothermal influence. The Sc/Cr ratio was greater than 0.14 indicating that the shales in the Mamfe basin were deposited in a normal water environment with no influence from hydrothermal processes. The binary discriminant diagram of TOC vs P and Co/Zn vs TOC shows that all the shales were not influenced by any hydrothermal processes during the time of their deposition.

Optimized Ridge–Furrow Ratio to Decrease Greenhouse Gas Emissions and Increase Winter Wheat Yield in Dry Semi-Humid Areas

The plastic-mulched ridge–furrow rainwater harvesting (RF) system has been widely adopted worldwide due to its visible economic benefits. However, few and inconclusive studies have focused on greenhouse gas (GHG) emissions. In addition, it is still unknown whether different coverage ratios under RF have an impact on greenhouse gas emissions. Here, we evaluate the effects of various coverage ratios on the soil hydrothermal characteristics, global warming potential (GWP), greenhouse gas intensity (GHGI), and yield productivity in dry semi-humid areas. A control (FP, conventional flat planting without mulching) and three different ridge–furrow ratios (40:40 (RF40), 40:60 (RF60), and 40:80 (RF80)) were tested in 2017–2019. Compared with FP, RF increased the soil temperature and promoted soil moisture in the furrows during the vegetative growth period. However, the soil temperature of the furrows slightly increased with furrow width, whereas the soil moisture obviously decreased under the three RF practices. In a wet year (2017–2018), FP significantly increased the winter wheat yield (43.6%) compared with RF, while the opposite was the case in a normal year (2018–2019). Among the three RF treatments, RF40 and RF80 significantly increased the yield by 13.9% and 17.2%, respectively, compared with RF60. Compared with FP, all of the RF treatments increased the flux of N2O and CO2 emissions but reduced CH4 absorption. Compared with FP, RF with ridge–furrow ratios of 40:40 cm, 40:60 cm, and 40:80 cm increased the GWP by 99.6%, 53.4%, and 31.3%, respectively, and increased the GHGI by 55.8%, 45.3%, and 0.7%, respectively. Therefore, conventional flat planting in wet years and a ridge–furrow ratio of 40:71 cm in normal years can reduce GHG emissions, sustaining crop productivity, and promote the sustainable development of agriculture and the environment.

Design and experiment of a straw clearing mulching no-tillage planter

When soybean is replanted after wheat in parts of China, problems such as a short sowing period, large straw yield and poor mechanization technology emerge; these problems increase the difficulty of sowing subsequent soybeans and negatively affect soybean quality and yield. In addition, the ecological problems associated with straw burning and soil degradation become increasingly severe. Here, a straw clearing mulching no-tillage planter with integrated functions of lateral straw clearing anti-blocking, precision sowing, pesticide spraying, and straw mulching was developed. This planter could perform several functions, including surface straw clearing before sowing, herbicide spraying after sowing, and straw surface uniform mulching. A lateral straw clearing mulching device was designed, and the main parameters and values affecting the working performance of the device were determined. To verify the technical performance and working quality of straw clearing mulching no-tillage sowing, field experiments were conducted, testing the effects of straw clearing mulching no-tillage sowing (SCMNS) and stubble eliminating rotary-tillage sowing (SERS) on the sowing quality, seedling emergence rate, soil hydrothermal characteristics, soybean yield, and comprehensive economic benefits. The qualified indices of seed spacing and sowing depth of SCMNS were 87.2% and 76.5%, respectively, which were significantly higher than those of SERS. SCMNS could enhance the ground temperature, reduce water evaporation, improve water storage, and promote soil moisture conservation. The seedling emergence date of SCMNS was one day earlier than that of SERS. The seedling emergence rate of SCMNS was 89.8%, which was significantly higher than that of SERS. The soybean yields of SCMNS (2809.2 kg·hm−2) and SERS (2207.4 kg·hm−2) significantly differed. SCMNS improved the comprehensive economic benefits by increasing soybean yield and reducing production costs; the net income of 1147.82 €·hm−2 was 50.27% higher than that of SERS.

Magnetization of nanofluid due to convectively heated bended surface with space-dependent heat generation

This research mainly focuses to study hydrothermal characteristics of magnetohydrodynamic nanofluid flow over a slippery permeable bended surface which is rotated in a circular cross-section with radius [Formula: see text]. In this nanofluid model, a nanoparticle concentration gradient is taken due to Brownian motion and thermophoretic force. Thermal conductivity and viscosity of nanofluid are a function of the local volume fraction of the nanoparticle. The system includes the most important parameters such as viscous dissipation and internal heat absorption (or) generation. For the supposed flow governing equations are formulated and then converted to a nonlinear system and resulted system is numerically evaluated with bvp4c in Matlab package. Multiple streamlines and three-dimensional graphics are provided to improve the results. The results obtained show that as the magnetic parameter values increase, the magnitude of the velocity field decreases and the pressure in the boundary layer decreases. Further, the parameters Brownian motion and thermophoresis increase the fluid temperature tends and the concentration should increase as the value of the slip parameter increases.

An Experimental and Numerical Investigation into the Durability of Fibre/Polymer Composites with Synthetic and Natural Fibres.

Progress in engineering research has shifted the interest from traditional monolithic materials to modern materials such as fibre reinforced composites (FRC). This paradigm shift can be attributed to the unique mechanical characteristics of FRCs such as high strength to weight ratio, good flexural strength, and fracture toughness. At present, synthetic composites dominate the automotive, aerospace, sporting, and construction industries despite serious drawbacks such as costly raw materials, high manufacturing costs, non-recyclability, toxicity, and non-biodegradability. To address these issues, naturally occurring plant fibres (such as jute, hemp, sisal) are being increasingly researched as potential reinforcements for biodegradable or non-biodegradable polymer matrices to produce environmentally friendly composites. In this study, sisal fibres were selected owing to their low production costs, sustainability, recyclability, and biodegradability. The hydrothermal ageing and mechanical characteristics of sisal fibre-reinforced epoxy (SFRE) composites were determined and compared with glass fibre-reinforced epoxy (GFRE) synthetic composites. Moreover, a first-of-its-kind numerical model have been developed to study the hydrothermal ageing and mechanical characteristics of SFRE, along with GFRE, using ANSYS software. Moreover, microstructural analysis of flexural tested GFRE and SFRE samples were carried out to identify the microstructural properties of the composites. Both experimental and numerical results exhibited an influence of short- or long-term hydrothermal treatment on the flexural properties of glass and sisal fibre-based composites. In the case of GFRE, the moisture uptake and fibre-matrix de-bonding existed, but it is less severe as compared to the SFRE composites. It was found that the dosage of sisal fibres largely determines the ultimate mechanical performance of the composite. Nonetheless, the experimental and numerical flexural strengths of SFRE were comparable to GFRE composites. This exhibited that the SFRE composites possess the potentiality as a sustainable material for advanced applications.

Newtonian hydro-thermal fluid fl 1 ow phenomena through a sudden 2 expansion channel with or without baffles

This work aims to study the different characteristics of Newtonian fluid flow and heat transfer througha 1:3 sudden expansion channel with or without plane baffles using the finite volume method. The flowis assumed viscous, incompressible, steady, and laminar. The different characteristics of hydro-thermalfluid flow phenomena have been studied for 𝑅𝑒 ∈ [0.1 − 200] to demonstrate the influence of thepresence of baffles. The profiles of velocity, pressure, skin friction coefficient, friction factor, averageNusselt number, and pumping power have been examined for both the cases of the presence and absenceof baffles. It has been observed that the hydro-thermal characteristics become more pronounced withthe increase in the number of baffles. In the case of three baffles of equal length, at 𝑅𝑒 = 200 it iscalculated that if the thickness of the baffles is same and equal to 10% of the length, then the value of Nu becomes approximately 1.2 times of that in the absence of baffle. For the same value of Re, ithas been found that for the presence of one baffle of length equal to the width of the inlet section of thechannel and of thickness 10% of the same, the value of 𝑁𝑢􀯔􀯩 becomes 1.11 times of that in the absenceof baffle, while in the case of three baffles of equal length and of equal thickness like the abovementioned case of one baffle, the value of 𝑁𝑢􀯔􀯩 becomes 1.25 times of that in absence of baffle. It hasalso been revealed that the enhancement of thermal phenomena increases with the increase inthe baffle’s height.

The effect of MHD flow on hydrothermal characteristics of ferro-nano-fluid in circular pipe

ABSTRACT In this study, the effect of the constant magnetic field (MF) on the convective heat transfer characteristics of Fe3O4/H2O ferro-nano-fluid with different nano-fluid volumetric concentrations (1.0%, 2.0%, and 5.0%) flowing in a circular pipe has been studied experimentally. Experiments have been conducted under laminar flow regime (1000≤ Re≤2300). Based on the experimental data, a good agreement has been found with the results and the well-known correlations in the literature. Also, it was obtained that increasing flow rate let to increase in Nusselt number. One of the most important results obtained is that the presence of MF offers up to 8.32% convective heat transfer enhancement compared with the absence of a MF. In addition, the constant MF applied externally to the flow is a key factor to control the convective heat transfer for such kind of geometry, which is widely used in thermal engineering systems.