Increase In Fluid Temperature Research Articles

Heat transfer in 3D radiative Oldroyd-B fluid flow with irregular heat source and activation energy

Heat transfer in 3D radiative Oldroyd-B fluid flow with irregular heat source and activation energy

Unfolding some numerical solutions for the magneto-hydrodynamics Casson-Williamson nanofluid flow over a stretching surface

Abstract This research focuses on exploring the significance of chemical reactions and thermal radiation on the magnetohydrodynamic (MHD) flow of a Casson-Williamson nanofluid (CWNF) over a stretching sheet. The objective is to comprehend how these factors influence the flow and heat transfer. A mathematical model, comprising partial differential equations (PDEs) adjusted into ordinary differential equations (ODEs) via utilizing some transformation. These ODEs are then tackled by MATLAB’s BVP4C method, which is part of the finite difference technique. Results are verified by comparison with existing literature and are depicted visually and in tabular format. Additionally, the study explores the effects of external factors such as magnetic fields and the Lewis number on parameters like Nusselt number, friction factor, and Sherwood number. Furthermore, heat generation in MHD Casson-WNF is analyzed, along with a thorough evaluation of heat transfer near a stretching sheet with a permeable layer. The findings suggest that growing Brownian motion factor (Nb) and thermophoresis coefficient (Nt) enhance the rate of heat transfer, signifying improved heat transfer rates. Similarly, higher Nt values are associated with enhanced Sherwood numbers, indicating better mass transfer. Conversely, higher Nb values lead in lower local Sherwood numbers. Physically, an increase in Brownian motion causes significant displacement of nanofluid particles, boosting their kinetic energy and thereby enhancing heat generation within the boundary layer. It is noted that the Eckert number (Ec) reflects the impact of different Ec values on temperature distribution. As Ec increases, there’s a proportional increase in fluid temperature due to frictional heating, which stores heat energy within the fluid. This effect becomes more pronounced for nonlinear stretching surfaces, demonstrating the response of the thermal region to viscous dissipation. Viscous dissipation has the potential to enhance convective heat transfer, leading to amplified temperature distribution and thickening of the thermal layer.

Double diffusive mixed convective flow over a wedge and cone in the presence of Brownian diffusion and thermophoresis parameter

The present article examines the double diffusion mixed convective nanofluid flow over a wedge and cone in which slip effects as Brownian motion and the thermophoretic parameter are considered. Mixed convective flow over wedges and cones is applied in different technical fields such as fiber technology, nuclear cooling systems, surface treatment, spray deposition techniques, and polymer production. Double diffusion is increasingly significant in scientific fields like astronomy, geosciences, oceanography, and chemical processes. Mixed convection occurs in several applications such as electric devices, solar panels, nuclear power plants, heat exchangers, radiators, and atmospheric boundary layer fluxes. The governing equations of the study are highly coupled nonlinear partial differential equations with surface constraints. The process of similarity transformation used to converts partial differential equations into nondimensional ordinary differential equations, which can be resolved using the MATLAB Bvp5c function. The graphical representation and detailed analysis of variations in velocity, temperature, and concentration distributions of nanofluids are presented. As the mixed convection parameter increases, the fluid’s velocity rises, with a more pronounced effect observed in the cone compared to the wedge. As the Brownian diffusion parameter grows, the fluid temperature increases, and velocity is more pronounced in the wedge scenario compared to the cone. Moreover, an increase in the thermophoresis parameter results in an elevation in the fluid’s temperature. Additionally, the wedge has a higher concentration of fluid and nanoparticles compared to the wedge. Fluid concentration falls with increasing Schmidt number, but fluid nanoparticle concentration decreases with increasing Lewis number.

The effects of thermal radiation, thermal conductivity, and variable viscosity on ferrofluid in porous medium under magnetic field

Purpose This study aims to analyze the two-dimensional ferrofluid flow in porous media. The effects of changes in parameters such as permeability parameter, buoyancy parameter, Reynolds and Prandtl numbers, radiation parameter, velocity slip parameter, energy dissipation parameter and viscosity parameter on the velocity and temperature profile are displayed numerically and graphically. Design/methodology/approach By using simplification, nonlinear differential equations are converted into ordinary nonlinear equations. Modeling is done in the Cartesian coordinate system. The finite element method (FEM) and the Akbari-Ganji method (AGM) are used to solve the present problem. The finite element model determines each parameter’s effect on the fluid’s velocity and temperature. Findings The results show that if the viscosity parameter increases, the temperature of the fluid increases, but the velocity of the fluid decreases. As can be seen in the figures, by increasing the permeability parameter, a reduction in velocity and an enhancement in fluid temperature are observed. When the Reynolds number increases, an increase in fluid velocity and temperature is observed. If the speed slip parameter increases, the speed decreases, and as the energy dissipation parameter increases, the temperature also increases. Originality/value When considering factors like thermal conductivity and variable viscosity in this context, they can significantly impact velocity slippage conditions. The primary objective of the present study is to assess the influence of thermal conductivity parameters and variable viscosity within a porous medium on ferrofluid behavior. This particular flow configuration is chosen due to the essential role of ferrofluids and their extensive use in engineering, industry and medicine.

A detailed 1D model of a parabolic trough solar receiver with a double-validation approach

This study proposes a detailed Parabolic Trough Collector (PTC) 1D model offering precise optical and thermal analysis. Our motivations were accuracy while ensuring fast and inexpensive computation. The proposed model differs from existing models by considering a more extensive set of possible optical and thermal losses, which to our knowledge have not previously been grouped together in a single model. Testing of the model based on experiments carried out by Sandia National Laboratories showed near-similar accuracy to much more complex models, with a mean standard deviation of 0.891% and 5.99 W/m2 for thermal efficiency and thermal losses respectively. These tests were carried out using two types of selective coating: cermet and black chrome, with two operating modes, namely vacuum and pressure annulus. To expand its scope of validity, the developed model was also tested using data from a selection of PTCs of commercial lengths (70, 106, 143, and 150 m) under real operating conditions. Additional validation of the model was carried out with available results from different heat transfer fluids (HTF), including two nanofluids. We highlighted that the deviation from the results of the various PTCs, although very satisfying in general, becomes more critical with increasing length and temperature, reaching a maximum outlet temperature deviation of around 2.14 °C. On the other hand, when switching from water to the nanofluid Water/CuO (5 %), the results show an increase in outlet fluid temperature from 325.91 to 334.73 °C. Experimental validation was also carried out using a 25 kW PTC test loop located at Ben Guerir. The average relative error perceived between simulation results and experimental measurements is estimated at 0.99 % for the steady-state test (based on the HTF temperature at the PTC outlet). An additional validation based on the external temperature of the glass envelope was also considered. This approach, which is rarely used in the literature, showed a relative error of around 4.39 % between simulations and experimental data, which remains within the uncertainty range of the thermal camera used.

Numerical simulation of magneto-hydrodynamic fluid flow with heat sink, chemical diffusion and Powell Eyring fluid behavior using Cattaneo–Christov source term

The aim of this study is to investigate the impact of magneto hydrodynamic Powell–Eyring fluid on double-diffusive phenomena, with a specific focus on employing the Cattaneo–Christov model. The purpose is to enhance the study's scope by incorporating a heat sink and chemical reactions, thereby analyzing the intricate interplay between heat transfer and chemical processes within the MHD fluid system. To achieve this aim, the study utilizes similarity variables to convert PDEs into ODEs. The primary objective is to gain insights into mass and heat transmission dynamics, placing a particular emphasis on understanding the influence of chemical reactions in the system. For numerical solutions during the analysis, MATLAB's BVP4C solver and the shooting technique are employed. The research further aims to explore various physical constraints, including the fluid Nusselt number and skin friction coefficient. By doing so, the study provides a comprehensive understanding of how the MHD fluid system responds to different conditions. The notable outcomes, presented through graphical representations and tables, include a discernible decrease in fluid velocity with a higher magnetic field parameter and an observable increase in fluid temperature with greater heat source constraints. In summary, this exploration subsidizes significantly to our considerate of complex fluid behavior and holds practical applicability in various scientific and engineering contexts. The novel and physical insights from the study offer valuable understanding into the impact of magneto hydrodynamic Powell–Eyring fluid, particularly concerning double-diffusive phenomena and the intricate interplay between heat transfer and chemical processes.

Experimental study of the influence of buoyancy on turbulent mixed convection in lead–bismuth eutectic flow under inclination conditions

The effects of inclination conditions on the heat transfer characteristics of lead–bismuth eutectic in a vertical circular tube are investigated experimentally. The results show that, compared to the vertical flow, inclination conditions result in lower wall temperature, increased fluid temperature and higher local heat transfer intensity of LBE. The effects of inclination conditions on the heat transfer characteristics of LBE flow decrease with increasing Reynolds number. Mixed convection determination criterion Y divides the heat transfer region into mixed convection and forced convection zones. The threshold value is around 2.0 × 10-3. The inclination conditions enhance the heat transfer characteristics only under mixed convection when the natural convection due to buoyancy force is more significant compared to the forced convection. The effects of inclination conditions increase with Y and inclination angle and decrease with Peclet number. The heat transfer correlation for LBE vertical flow cannot predict the Nusselt number under inclination conditions well. Therefore, a relevant empirical correlation for inclination conditions is developed. The research would be helpful for the mechanism analysis and engineering design when liquid metals are applied for motion conditions.

Gold and Arsenic in Pyrite and Marcasite: Hydrothermal Experiment and Implications to Natural Ore-Stage Sulfides

Hydrothermal synthesis experiments were performed in order to quantify the states of Au and As in pyrite and marcasite. The experiments were performed at 350 °C/500 bar and 490 °C/1000 bar (pyrite–pyrrhotite buffer, C(NaCl) = 15 and 35 wt.%). The synthesis products were studied by EPMA, LA-ICP-MS, and EBSD. The EPMA was applied for simultaneous determinations of Au, As, Fe, and S, with a Au detection limit of 45–48 ppm (3σ). The analyses were performed along profiles across zonal grains. The concentrations of As and Au up to 5 wt.% and 8000 ppm, respectively, were determined in pyrite and up to 6 wt.% and 1300 ppm in marcasite. In pyrite, the Au concentration decreases with fluid salinity and temperature increases. Strong positive Au–As correlation and strong negative Au–Fe and As–S correlation were identified in pyrite. Comparison of the correlations with theoretical lines implies Au–As clustering. The cluster stoichiometry is inferred to be [AuAs10]. Most probably, As in pyrite presents in the form of clusters and in the As→S solid solution. Incorporation of Au in As-rich pyrite can be controlled by the reductive deposition mechanism. In marcasite, the concentrations of Au are not correlated with the As content. The [AuAs10] clusters enrich the {210}, {113}, and {111} pyrite faces, where the former exhibits the highest affinity to Au and As. The affinity of {110} and {100} forms to Au and As is lower. Implication of the experimental results to data for natural auriferous pyrite shows that the increase of Au content at C(As) > 0.5–1 wt.% is caused by the incorporation of the Au-As clusters, but not because of the formation of Au→Fe solid solution. Therefore, the concentration of “invisible” gold in pyrite is dictated solely by the hydrothermal fluid chemistry and subsequent ore transformations.

Micropolar flow and heat transfer within a permeable channel using the successive linearization method

Abstract This research investigates the flow of micropolar fluid and heat transfer through a permeable channel using the successive linearization method (SLM). The study considers parameters such as coupling, spin-gradient viscosity, and micro-inertia density. The partial differential equations involved are transformed into a system of ordinary differential equations using similarity variables. The resulting nonlinear equations are solved using the SLM technique, and their accuracy and computational efficiency are validated through comparative analysis with previous results. The study shows that increasing the parameters of coupling and spin-gradient viscosity has a positive impact on fluid flow, microrotation, heat transfer, and mass transport, as demonstrated by the increased dimensionless profiles. Conversely, an increase in the micro-inertia density parameter leads to a reduction in these profiles. This decrease can be attributed to the increase in the micro-inertia effect of fluid flow and heat transfer, resulting in a decrease in convection and a change in the flow pattern in the channel. Additionally, higher Reynolds numbers are associated with decreases in velocity, microrotation, temperature, and concentration distribution. This implies a reduction in fluid flow intensity, weaker heat transfer, and decreased mass transport. However, an increased Peclet number results in increased fluid temperature and concentration profiles, indicating enhanced thermal convection and mass transport. These findings have significant implications for applications involving micropolar fluids, such as lubrication systems, blood flow, microchannels, and filtration systems.

CFD-DEM simulation of proppant pack stability during flowback in a rough fracture using supercritical CO2

The destabilization of proppant packs during flowback, leading to undesirable consequences such as choke points (fracture closure near the wellbore) and proppant production, is a critical concern in fracturing operations. Despite its significance, comprehensive investigations into proppant pack stability during flowback remain limited, particularly in supercritical CO2 (Sc-CO2) fracturing. This study addresses this gap by employing an experimentally validated coupled Computational Fluid Dynamics–Discrete Element Method (CFD–DEM) model, integrated with a heat transfer model, to analyze proppant pack stability in Sc-CO2 fracturing near the wellbore. An authentic proppant pack for flowback analysis is generated by simulating proppant pack development during the pumping stage and subsequent compression during the fracture closure stage in a synthetic rough fracture. The findings reveal that the flowback stage can be subdivided into three stages: translation-controlled, rolling-controlled, and stable. Proppant pack stability is intricately governed by factors such as fluid drag force, inter-particle contact force, and pre-flowback pack shape. Due to the reduced fluid drag force, the retained proppant ratios rise under varied conditions: from 47.6% to 95.7% with a decrease in flowback rate from 0.3 m/s to 0.1 m/s, from 50.0% to 67.8% with an increase in fluid temperature from 40 °C to 160 °C, and from 16.5% to 80.8% with an increase in proppant size from 0.4 mm to 0.8 mm. In comparison, due to the increased inter-particle contact force, the retained proppant ratio increases by 16.4% as the closure width increases from 0.15 mm to 0.3 mm. Additionally, a longer proppant pack with a front characterized by a higher inclination angle and curved zone exhibits higher stability during flowback. These insights significantly enhance the understanding of proppant pack stability during flowback, offering crucial guidance for designing Sc-CO2 fracturing processes.

Effect of the X-grid static mixer flow inserts on the performance of parabolic trough collector

Solar energy is a very convenient and reliable renewable energy source to fulfill our society's wide variety of energy requirements. Solar concentrator-based energy technologies are the best way to utilize solar energy nowadays. Among those technologies, PTC (Parabolic Trough Collector) is a well-mature and reliable concentrating solar power technology having various real-world applications with solar standalone as well as in hybrid modes. For improving the performance of PTC, flow inserts are a very promising technique. This work aims to investigate the X-grid static mixer flow inserts on the performance of the PTC module. Here, X-grid static mixer flow inserts are modeled and compared with the simple cylindrical tube without any inserts inside by using a validated model in Ansys Fluent 18.1. Evaluation criteria include flow analysis, overall efficiency, exergy efficiency and thermal efficiency. The overall efficiency and exergy efficiency are the most prominent factors for the evaluation of PTC performance. The PTC is analyzed with various inlet fluid temperatures ranging from 303 K to 653 K with a variation in the volumetric flow rate ranging from 50 LPM (Litre Per Minute) to 250 LPM. The enhancement in the thermal performance of PTC using an X-grid static mixer is more as the inlet fluid temperature increases. The pressure drop increases multiple times with the use of X-grid flow inserts, but the overall rise of pump work is low. Overall thermal efficiency is higher for the X-grid static mixer than the plain tube which is mainly used in the PTC. The presented investigation results can be helpful for the design of X-grid static mixer.

Heat source/sink impact on wave oscillations of thermal and concentration boundary layer along inclined plate under lower gravitational region

The force of attraction between two masses increases as gravity increases. Gravity is very important mechanism for mass transfer characteristics across the inclined shape. The significant purpose of current study is to examine amplitude in mass transfer under reduced gravity-driven flow. The impact of heat source/sink on periodic mixed convective gravity-driven flow across the inclined plate has been evaluated. The oscillatory characteristics of heat rate and mass transmission are explored at three inclined angles π/6, π/4 and π/3. The gravity is assumed under maximum temperature difference. The governing dimensional model is transformed into non-dimensional equations with appropriate scaling variables. The non-dimensional equations are again reduced in non-oscillatory, real and imaginary parts. For smooth coding, the primitive formulation is used with finite difference method to change non-dimensional forms in algebraic system. The algebraic equations are solved with Gaussian elimination scheme to display velocity field, temperature distribution and rate of concentration numerically. The impact of heat source/sink ±δ, reduced gravity Rg, buoyancy variable λT, modified buoyancy factor λC, Prandtl factor Pr, reduced gravitation factor Rg, and Schmidt variable Sc on the oscillating behavior of shear stress, rate of fluctuating heat transfer, and rate of fluctuating mass transfer is secured. It is found that the amplitude of fluid velocity and temperature increases for each parameter under heat source +δ=0.4. It can be seen that concentration distribution increases as reduced gravity Rg increases under heat sink −δ=0.3. It can be seen that amplitude of shearing stress and heat transfer increases as heat source +δ increases. It is obtained that oscillation in mass transfer increases as heat source/sink ±δ increases under reduced gravitation Rg=1.2.

Performance of energy piles foundation in hot-dominated climate: A case study in Dubai

Energy piles represent an innovative technology that can help provide sustainable geothermal heating or cooling energy for thermal conditioning purposes. In hot-dominated climates, the interest is to inject heat in the ground and extract energy for space-cooling purposes. This study evaluates the feasibility of energy piles in these regions through three-dimensional numerical modelling. The modelling framework is validated against a published experiment and is able to sufficiently capture the development of outlet temperature over time. The numerical analysis is then used to evaluate a case study in Dubai where it is targeted to provide 40 % of the cooling demand of a typical building. The unbalanced energy demand causes an increase in the outlet temperature of the heat carrier fluid and the radial temperature over time. However, observation of long-term behaviour indicates that the temperature increase is most significant in the initial years and gradually stabilizes over time. This stabilization enables to respect the outlet temperature limitation of the heat pump over 50 years. A sensitivity analysis confirms these observations with respect to system dimensioning variables. The obtained results highlight the effectiveness of energy piles to decarbonize energy supply in buildings in hot-dominated climates via the use of renewable energy sources.

Magnetohydrodynamic Darcy-Forchheimer Squeezed Flow of Casson Nanofluid Over Horizontal Channel with Activation Energy and Thermal Radiation

The most well-known research areas in computational fluid dynamics are concerned with the interplay of fluid flow with chemical reaction and activation energy. According to the findings of several studies, its industrial applications include simulating the flow inside a nuclear reactor, for which it has received appreciation from many researchers. This study, driven by the use of flow in industrial challenges, explores the impacts of activation energy and chemical reaction on the magnetohydrodynamic (MHD) Darcy–Forchheimer squeezed Casson fluid flow through a porous material across the horizontal channel. The flow is produced when two horizontal plates are compressed to create more space between them. By using similarity variables, one may successfully convert partial differential equations (PDEs) to ordinary differential equations (ODEs). The shooting technique was used to carry out the numerical analysis, which entailed solving the competent governing equations with dominating parameters for a thin liquid layer. This was done to determine the results of the study. To validate the current solutions, it is vital to evaluate the numerical findings alongside the results of the prior research. The findings indicate that fluid velocity and temperature increases may be expected as the plates are brought closer together. In addition, there was a correlation between a rise in the Hartmann number and a decrease in the fluid’s velocity and concentration because of the existence of strong Lorentz forces. The temperature and the concentration of the liquid will increase due to the Brownian motion. When the Darcy–Forchheimer and activation energy parameters are both increased, the velocity and concentration decrease.

Computational investigation of homogeneous-heterogeneous reactions in fluid with transport mechanisms: A finite element simulations approach

There are numerous applications in engineering and industry for homogeneous and heterogeneous chemical reactions in fluid regimes under the influence of nanoparticles and hybrid nanoparticles. This article models homogeneous and heterogeneous chemical reactions in the flow of polymer liquid (glycerin) containing Cu-Al2O3 in the presence of heat and mass transfer. The finite element method is used to quantitatively solve these models. A 76% increase in wall shear stress for the case of simultaneous dispersion of Cu and Al2O3 in comparison of only dispersion of Cu is noticed. Similarly, 44% increase in wall heat flux in noticed due to dispersion Cu and Al2O3 in comparison of dispersion of Cu only. The vortex parameter is responsible for a significant increase in the macro-motion of the fluid particles. Macro-motion gets more influence of micro motion than the influence of micro-motion on the macro-motion of Cu-Al2O3- polymer. To control momentum boundary layer thickness, reduce the diameter of the circular pipe. Magnetic force has the opposite direction of flow. Therefore, fluid motion is a decreasing function of magnetic field intensity. Further, the Lorentz force (magnetic force) for the case of Cu-Al2O3 - polymer is stronger than that for the case of Cu- polymer. Additionally, it can be seen that Cu-Al2O3- polymer experiences more Joule heating than Cu- polymer does. The micromotion is compromised when the curvature parameter is increased. As a result, convective transport slows down and the temperature of Cu- polymer and Cu-Al2O3 - polymers decreases. The result, the rate of conversion of electrical energy into heat speeds up intensity of magnetic field increase as and therefore, fluid temperature increases.

Computational assessment of thermally stratified magnetohydrodynamics Maxwell nanofluid with Joule heating and melting heat transfer

Researchers have reported an excellent desire for power storage devices that are more reliable and long-lasting. Battery storage devices are used in waste-to-energy recovery, wind power, mixed energy generation, and heating reactor designs. There are three more helpful methods for storing heat energy: Latent heat storage, like sensible heat storage and chemical heat storage, is a type of energy storage. In these processes, latent thermal energy storage is quite expensive and productive. Melting is a technique for storing heat energy in a material. The substance is frozen to release the stored heat energy. Melting phenomena include freezing a ground-based pump’s heat exchanger coils, tundra melting, magma solidification, and semiconducting processes. Because of the importance mentioned above, the current study investigates the behavior of a two-dimensional Maxwell nanofluid with heat radiation influence across a stretchable surface. The melting process, quadratic thermal and solutal stratification viscous dissipations, and Joule heating effects will also be examined. The impacts of Brownian motion and thermophoresis diffusion will also be assessed. Moreover, the binary chemical reaction will be included when evaluating the MHD mixed convective flow. The governing nonlinear equations of velocity, temperature, and concentration of nanoparticles will also be used to form the constructed fluid model. Under the boundary layer approximation, the equations governing the problem are reduced into non-linear and dimensionless ordinary differential equations using appropriate transformations. The dimensionless governing equations are solved using the convergent approach. The Maxwell fluid parameter enhances while the magnetic field parameter decreases the velocity of the nanofluid, which is one of the most noteworthy findings of the study. However, when the Brownian motion and thermophoresis parameters increase, the fluid temperature increases. The decrease occurs in the concentration profile with improving solutal stratification estimations while growing with enhancing chemical reaction parameters. With the increase in nanoparticle volume fraction, the nanofluid’s temperature decrease, but the nanofluid’s velocity improves.

Numerical performance investigation of a photovoltaic-thermal hybrid collector-evaporator with different tube configurations for heat pumps

Surface temperature build-up due to the continuous conversion of incident sunlight to heat deteriorates the power output, efficiency, and life of photovoltaic panels. Photovoltaic-thermal (PV-T) systems provide a potential solution to avoid excessive heating of PV panels, simultaneously providing useful heat energy. A heat extraction unit is attached to the PV panel in PV-T systems that extract and convert the waste heat into useful heat. Therefore, design and material selection are keys to better performance in the system-level approach. Additionally, it is a cumbersome task dealing with refrigerant-based heat and fluid flow interactions in a system-level approach. With this in perspective, this paper analyzes different materials and flow configurations of PV-T systems. A transient, three-dimensional turbulence solver coupled with heat transfer through solids and liquids physics is modeled using COMSOL Multiphysics software. R-32 refrigerant acts as the heat transfer fluid in the system loop. The conservation equations are discretized using the finite element method. The present study involves two different plate materials (aluminum and copper) and three flow configurations (serpentine, roll-bond, and spiral) with and without absorber plates. A total of eight different configurations are being investigated here. The obtained results suggest that with the absorber plate, the performance increases significantly with a PV panel temperature decrease of 4–5 K, and the outlet fluid temperature increase by 2–8 K. It was observed that the performance difference between copper and aluminum plate is minimal (2%). Roll-bond flow configuration has scope for further research since it is more efficient than others because of the larger contact area for heat transfer.

Dynamic stability of slightly curved tensioned pipe conveying pressurized hot two phase fluid resting on non uniform foundation

The dynamic stability of slightly curved tensioned pipes conveying pressurized two phase fluid, under thermal loadings are investigated in this paper. Furthermore, these pipes are resting on nonuniform elastic foundations. The equation of motion of the system is derived using the extended Hamilton’s principle for open dynamic systems and considering the Euler–Bernoulli theory for slender beams. The free vibration and the effects of two phase fluid flow, geometric imperfections, thermal, tension and pressure on the pipe system resting on nonuniform foundations are investigated numerically. Three different boundary conditions (BC) are considered, namely simply-simply (SS) supported, simply-clamped (SC) supported and clamped-clamped (CC) supported. The numerical method of Finite Element was used on the partial differential equation. This method is used to accurately predict steady state natural frequency responses of a dynamical system through several numerical investigations. It was found that the stability of slightly curved pipes conveying two phase flow are significantly affected by the boundary condition. It is shown that the initial curvature term increases the critical velocities for all the nine modes considered, the increase is significant in the first and second critical velocities compared to the other modes. Initial curvature effect is more pronounced in simple supported ends. Further-more the influence of the fluid velocity, temperature, pressure and axial tension is analysed; the results show that the vibration frequency decreases when the fluid velocity, temperature, and pressure increase or the axial tension decreases, and the critical fluid velocity decreases when the temperature and pressure increase or the axial tension decreases. For the pipe on nonuniform foundation, an increased stiffness leads to an increased in the first critical velocity for all the BC. However, the pattern of the increment depends on the attachment parameter, initial curvature, and the vapour quality. Some of these results are completely absent in pipes conveying single flows.

Analysis of Homogeneous/Heterogeneous Reactions in an Electrohydrodynamic Environment Utilizing the Second Law.

In this study, we investigate what happens to entropy in the presence of electrokinetic phenomena. It is speculated that the microchannel has an asymmetrical and slanted configuration. The presence of fluid friction, mixed convection, Joule heating, presence and absence of homogeneity, and a magnetic field are modelled mathematically. It is also emphasized that the diffusion factors of the autocatalyst and the reactants are equal. The governing flow equations are linearized using the Debye-Huckel and lubrication assumptions. The resulting nonlinear couple differential equations are solved using the program's integrated numerical solver, Mathematica. We take a graphical look at the results of homogeneous and heterogeneous reactions and talk about what we see. It has been demonstrated that homogeneous and heterogeneous reaction parameters affect concentration distribution f in different ways. The Eyring-Powell fluid parameters B1 and B2 display an opposite relation with the velocity, temperature, entropy generation number, and Bejan number. The mass Grashof number, the Joule heating parameter, and the viscous dissipation parameter all contribute to the overall increase in fluid temperature and entropy.

A numerical study on thermo-hydraulic performance of micro pin-fin heat sink using hybrid pin-fins arrangement for electronic cooling devices

PurposeThis study aims to examine the effect of a combination of hybrid pin-fin patterns on a heat sink's performance using numerical techniques. Also, flow characteristics have been studied, such as secondary flow formation and flow-wall interaction.Design/methodology/approachIn this study, the effect of hybrid arrangements of elliptical and hexagonal pin-fins with different distribution percentages on flow characteristics and performance evaluation criteria in laminar flow was investigated. Ansys-Fluent software solves the governing equations using the finite volume method. Also, the accuracy of obtained results was compared with the experimental results of other similar papers.FindingsThe results of this study highlighted that hybrid arrangements show higher overall performance than single pin-fin patterns. Among the hybrid arrangements, case 3 has the highest values of performance evaluation criteria, that is, 1.84 in Re = 900. The results revealed that, with the instantaneous change in the pattern from elliptic to hexagonal, the secondary flow increases in the cross-sectional area of the channels, and the maximum velocity in the cross-section of the channel increases. The important advantages of case 3 are its highest overall performance and a lower chip surface temperature of up to about 2% than other hybrid patterns.Originality/valuePrior research has shown that in the single pin-fin pattern, the cooling power at the end of the heat sink decreases with increasing fluid temperature. Also, a review of previous studies showed that existing papers had not investigated hybrid pin-fin patterns by considering the effect of changing distribution percentages on overall performance, which is the aim of this paper.