Ag-water Nanofluid Research Articles

Mixed convective nanofluid flow and heat transfer induced by a stretchable rotating disk in porous medium

AbstractEnhancement of “heat transfer” using “nanofluid” has diverse potential applications in heat exchangers, thermal management of electric devices, cooling of tractors, solar thermal systems, manufacturing of paper, and many others. Hence, the aim of the current investigation is to explore the impacts of “mixed convection” on “nanofluid flow” over a permeable rotating disk, which is stretched radially in a porous medium. Variable wall “temperature” and “convective boundary conditions” are also considered here. This makes the present investigation different from others. The suitable “similarity transformations” are imposed to alter the governing partial differential equations into a set of coupled ordinary differential equations (ODEs). Then, these ODEs are solved numerically by the “4th order Runge‐Kutta method” using the “shooting technique” with the help of the bvp4c package in MATLAB software. The effects of fluid controlling “parameters” on “flow and thermal fields” as well as “skin friction coefficient” and “Nusselt number” are presented graphically and explained physically. Due to enhanced rotation of the disk, the radial and azimuthal velocity of the fluid increase and the temperature of the fluid decreases. Most importantly, it is observed that when the disk rotates faster than the stretching rate, the temperature of the nanofluid decreases rapidly, which has wider applications for cooling purposes. It is also noted that when the suction parameter increases its value from −1 to 1, for Ag–water nanofluid, the “skin friction coefficient” decreases by 73.56%, and the Nusselt number also decreases by 24.11%, and for Fe3O4–water nanofluids, the “skin friction coefficient” decreases by 71.25% and the Nusselt number decreases by 24.47%.

Experimental study and performance enhancement of a novel micro heat pipe photovoltaic/thermal system in a cold region

The photovoltaic/thermal (PV/T) system, which utilizes solar energy to generate electricity and thermal energy, has significant potential in the northwest region of China, an area with abundant solar irradiation. To improve the performance of the micro heat pipe PV/T system, the study analyzed the system's thermal collection efficiency and power conversion efficiency using numerical simulation of the PV/T panel. The model incorporated double-layer glass and replaces water with nanofluid as the working medium inside the airfoil heat exchanger. The average relative error of the model was 0.9 %. In experiments conducted in Lanzhou, located in the northwest region of China, the power conversion efficiency reached its peak of 12.64 % during winter, while the thermal collection efficiency reached its maximum of 39.45 % during summer. Moreover, utilizing R141b as the working fluid in the micro heat pipe resulted in an average increase of 7.14 % in thermal collection efficiency and an average increase of 4.46 % in power conversion efficiency compared to acetone. This indicated that R141b outperforms acetone in terms of system performance. The study observed that the highest overall efficiency is achieved when the air layer thickness of the double-layer glass is 11 mm. The thermal resistance between the inner wall of the airfoil heat exchanger and the water in the PV/T components was the highest, reaching 48.85 %. Therefore, it was necessary to use nanofluids instead of water to reduce the thermal resistance of PV/T modules. The system performance remained relatively stable when the volume fraction reaches 8 %. At this volume fraction, the Al2O3-water nanofluid, Cu-water nanofluid, and Ag-water nanofluid increased the power conversion efficiency by 0.34 %, 0.72 %, and 0.77 % respectively. Moreover, they improved the thermal collection efficiency by 1.16 %, 2.69 %, and 2.78 % respectively. The micro heat pipe PV/T system was utilized for winter heating of farmers in Lanzhou and Jinchang cities. It maintained an indoor temperature of over 16 ℃ throughout the day, thus meeting the indoor heating standards.

MHD Mixed Convection Inside Double-wall-driven Enclosure Containing Ag-water Nanofluid and Center Heater

MHD Mixed Convection Inside Double-wall-driven Enclosure Containing Ag-water Nanofluid and Center Heater

Impacts of nanoparticle shapes on Ag-water nanofluid thin film flow through a porous medium with thermal radiation and ohmic heating

Impacts of nanoparticle shapes on Ag-water nanofluid thin film flow through a porous medium with thermal radiation and ohmic heating

Effectiveness of silver-magnesium oxide-water hybrid nanofluid in Couette channel

The present article numerically investigates the unsteady magnetohydrodynamic (MHD) Couette flow containing novel (Ag + MgO)-water hybrid nanofluid (HNF). The nanoparticles of silver (Ag) and magnesium oxide (MgO) are supplemented to base fluid water. The top wall is kept in uniform motion while the bottom wall of channel set stationary and stretchable. An external magnetic field is applied perpendicular to lower plate. The governed nonlinear partial differential equations (PDE) are solved employing finite difference method (FDM). The effects of hybrid nanofluid and nanofluid (NF) are compared for the significant parameters and presented graphically. The results illustrate that (Ag + MgO)-water HNF exhibits significant influence over Ag-water NF on velocity and temperature in the Couette channel.

Entropy analysis and mixed convection of nanofluid flow in a pillow plate heat exchanger in the presence of porous medium

A pillow plate heat exchanger (PPHE) is one of the types of heat exchangers that haven't received the attention they deserve despite their high efficiency and operational capability. A unique feature of PPHEs is their pillow-shaped structure, which is achieved through hydroforming. In light of this, scholars have been interested in analyzing and optimizing the thermo-hydraulic properties of PPHEs. In this study, the interior of the PPHE was occupied with a permeable substance with a high porosity percentage (0.9034 ≤ ɛ ≤ 0.9586 and 0.00015 ≤ dp ≤ 0.00065) and saturated with Ag-water (0 ≤ϕ ≤ 0.06) nanofluid, which has a profound influence on the heat transfer rate of PPHEs. In order to analyze the determinants affecting the heat transfer rate of PPHEs under these conditions, the governing equations were solved using the finite volume method and also the Brinkman-Forchheimer-extended Darcy equation. According to the results, heat transfer is enhanced in PPHE when using a permeable medium with high porosity and a small pore size. That is, PPHEs transfer heat more efficiently when they are placed in a denser porous medium because heat conduction is boosted. Moreover, due to the increased thermal conductivity of the nanoparticles, the application of nanoparticles to the base fluid also enhanced heat transfer and Nusselt number. However, decreases in friction factor and entropy generation were observed with increasing porosity, pore size, and Darcy number, due to reduced flow resistance. A decrease in Richardson number also results in a decrease in friction factor and entropy generation. At the wake region of welding spots, the velocity has reached its lowest values; consequently, this led to a reduction in the heat transfer rate. Nevertheless, within dense porous media, at the lower hydraulic diameter points, the conduction contributes to heat transfer improvement. The porous medium acts as a heat sink and absorbs the heat from the welding spot. This allows the heat to be dissipated away from the welding spot, which reduces the velocity and heat transfer rate. The nanofluid, on the other hand, helps to increase the thermal conductivity of the medium, resulting in more heat being transferred to the surrounding material. Consequently, the results demonstrated that PPHEs' thermal and thermodynamic performance could be significantly improved by using a porous medium saturated with nanofluid.

Artificial intelligent modeling and optimization of pin-fin configuration on the thermal performance of two tubes inside phase change material for cooling of a solar panel using Ag-water nanofluid

This paper performs a two phase numerical analysis on a solar thermal panel of dimensions 80 × 100 cm in the presence of Ag-water nanofluid flow. The nanofluid flows in two individual tubes beneath the panel, and there are some circular pin fins on the tubes. Tubes and pin fins under the panel are surrounded with a phase change material (PCM), paraffin wax. By increasing the length of pin fins from 1 to 7 cm, the volume fraction (VOF) of molten PCM, outlet nanofluid temperature (T-NF), and heat transfer coefficient (HTC) are examined from the transient state up to reaching the steady state. Utilizing a FEM based on a weak form, namely Galerkin, to find a numerical solution for mathematical modeling. Results of this study indicated that increasing the length of pin fins from 3 to 7 cm maximally increases the outlet nanofluid flow up to 2.11 °C. In the transient conditions, increasing the length of pin fins decreases the VOF of molten PCM. When the problem is evaluated in the transient conditions, increasing the length of pin fins decreases the mean temperature of the panel (T-PL), but in the steady-state conditions, the T-PL is the same for different lengths of pin fins. The lowest value of the HTC occurs for pin fins of length 3 cm, and in most cases, the average HTC is maximum for pin fins of length 1 cm.

Second Law Analysis for Free Convection in an L-Shaped Cavity Filled with Nanofluid

The paper aims to analyze the effects of various Prandtl number and different nanoparticles for heat transfer and entropy generation of free convection laminar fluid flow in an L-shaped cavity filled by nanofluid. To investigate the second law characteristics of free convective flow and heat transfer from an L- shaped geometry filled by water and nanofluids (Cu-water, Ag-water, Al2O3-water), the effects of Prandtl number and various nanoparticles on the average Nusselt number, total entropy generation and Bejan number has been numerically analyzed. Isotherms, stream function and entropy generation caused by heat transfer are also presented for various Prandtl numbers and various nanoparticles. The governing equations are solved using penalty finite element method with Galerkins weighted residual technique. The results reveal that Ag-water nanofluid with highest Prandtl number gives the highest amount of irreversibility as well as rate of heat transfer. Cu-water and Ag-water nanofluid produces more irreversibilities than Al2O3-water nanofluid and base fluid. Also the results show that the Nusselt number and Bejan number increase with the increase of Prandtl number. Therefore, Prandtl number may be an important parameter for desired heat transfer increment with decreasing entropy generation in the given geometry.

A Comparative Thermal and Economic Investigation of Similar Shell & Tube and Plate Heat Exchangers with Low Concentration Ag-H2O Nanofluid

Plate Heat Exchanger (PHE) and Shell and Tube Heat Exchanger (STHE) with identical heat transfer areas and material characteristics are proposed and a comparative thermal and economic comparative analysis is carried out on both exchangers. Ag-water nanofluid is used at low concentrations (0, 2.5, 5, 10 mg/L), flow rates (2, 5, and 8 L/min), and inlet temperatures (36, 46, and 56 °C) as hot flow and the heat transfer coefficient (U), electrical power consumption of the pump, and costs per unit of average U value are considered as the calculated parameters for each heat exchanger in co-current and counter-current flows. The results revealed that PHE generates a higher U value compared to the STHE under different Ag-water nanofluid concentrations. This is due to the existence of grooves on the plates of PHE which generates turbulent flow. The impact of nanofluid concentration on U is negligible for lower concentrations in both PHE and STHE. It is also found that the nanofluid flow rate has the highest impact on the U value, just like conventional fluid. Besides, even though counter-current flow increases the U values for both PHE and STHE, the flow pattern has a higher impact on the U value of PHE than that of STHE. For both PHE and STHE, increasing the nanofluid flow rate enhances the amount of U. However, the effect of flow rate on the U value of PHE is greater than that of the STHE. It is also shown that throughout the entire experimental temperature domain, PHE has had higher performance than STHE, and as the fluid temperature increased from 36 to 56 °C, there was a slight increase in the overall heat transfer of both PHE and STHE. Furthermore, for the same flow rate, both PHE and STHE had almost the same pump power consumption, and increasing the nanofluid flow rate from 2 L/min to 8 L/min promoted the electrical power consumption of the pump. Finally, we found that the costs per unit of heat transfer coefficient for PHE are significantly lower than STHE. The presented results also indicated that using a vortex generator at the inlet of STHE tubes, to form turbulent flow, increases the U values of STHE for both co-current and counter-current flows but these U values are lower than the corresponding U values of PHE. Small plates gap in PHE structure cause higher fluid flow velocities and create a chain-like structure of nanoparticles (NPs) between PHE’s plates (especially at higher nanofluids concentrations).

An application of spectral linearisation method on the steady two-dimensional radial flow of Au-water and Ag-water nanofluids between two inclined plane walls

The present work purveys the steady two-dimensional viscous incompressible radial flow of Au-water and Ag-water nanofluids between plane walls which either converge or diverge in the presence of MHD effect. A uniform magnetic field is applied. The governing partial differential equations of the present physics and their appropriate boundary conditions are initially cast into the dimensionless forms to reduce into the ordinary differential equation. The resulting equation thus formed is then solved by adopting the spectral linearisation method (SLM) to get the accurate numerical solution. Solution errors and residual norms were analysed to elaborate the convergence and accuracy of the numerical solution. The present results are validated with favourable comparisons to previously published results due to the current investigations' unique cases. Parametric study of the governing parameters, namely the magnetic field strength parameter M, Reynolds number Re, angle of inclination α, and the volume fraction parameter ɸ on the non-dimensional velocity is conducted. The analysis discloses that the profiles of the flow are largely impacted by the physical parameters.

An application of spectral linearisation method on the steady two-dimensional radial flow of Au-water and Ag-water nanofluids between two inclined plane walls

An application of spectral linearisation method on the steady two-dimensional radial flow of Au-water and Ag-water nanofluids between two inclined plane walls

Application of Successive Linearization Method on Steady Radial Flow of Nanofluids Between Inclined Plane Walls

The present work purveys the heat transfer enhancement in the steady two-dimensional viscous incompressible radial flow of Au-Water and Ag-Water nanofluids in the presence of MHD effect between the stationary convergent/divergent channel walls which are permitted to stretch or shrink. A uniform magnetic field is applied. The governing partial differential equations of the present physics and their appropriate boundary conditions are initially cast into dimensionless forms to reduce into the ordinary differential equations. The resulting equations thus formed are then solved by adopting the Successive Linearization Method (SLM) to get the accurate numerical solution. Solution errors and residual norms are analyzed to elaborate the convergence and accuracy of the numerical solution. The behavior of thermal conductivity of both types of nanofluids is examined for converging channel and diverging channel cases under the uniform magnetic field effect. The present results are validated with favorable comparisons with previously published results as the current investigations’ unique cases. A parametric study of the governing parameters, namely the magnetic field strength parameter, Reynolds number, angle of inclination, and the stretching parameter on the non-dimensional velocity and temperature, is conducted. Analysis discloses that the profiles of the flow are largely impacted by the physical parameters. It is noticed that the magnetic parameter deploys an enhancing influence on fluid velocity profile as well as heat transfer rate, and the effect of the magnetic field is less pronounced on Au-water nanofluid than that of the Ag-water nanofluid. The fluid velocity increases as the values of Re increase for both the nanofluids in the convergent channel and decreases in the case of the divergent channel. Fluid temperature increases as Re increases for the divergent channel. The velocity of both the nanofluids increases as the angle of inclination of the plates increases.

Two-phase simulation of irreversibilities for Ag–water nanofluid flow inside an elliptical pin-fin heat sink: Entropy generation and exergy considerations

It is beyond doubt that the first-law perspective is incapable to evaluate the energy losses, and realizing real optimum conditions of thermal equipment only boils down to the second law of thermodynamics. This paper examines the second law phenomena of a nanofluid within an elliptical pin-fin heat sink. The current outcomes provide the design insight for developing optimum pin-fin heat sinks for use in high-performance electronic devices. The numerical modeling based on the finite volume method is adopted. Elliptical pin fins with a larger fin density cause lower thermal irreversibility. The higher fin density intensifies the frictional irreversibility at higher Reynolds numbers. Adding the nanoparticles improves the temperature uniformity and causes less thermal entropy generation, while it augments the frictional irreversibility. Depending on the Reynolds number, there are optimum values of the fin density at which the minimum irreversibility happens. The Bejan number gradually declines as the fin density rises.

Numerical investigation on thermal performance of battery module with LCP‐AFC cooling system applied in electric vehicle

AbstractTo improve the thermal performance of electric vehicle batteries, a novel cooling system of liquid cold plates coupled with air flow channels (LCP‐AFC) for battery thermal management was proposed. Three‐dimensional models were established for simulation. The effects of five factors on the heat dissipation of the electric vehicle battery module were studied, which included the battery discharge rate, inlet temperature of cooling liquid, nanofluids, airflow velocity, liquid, and air flow directions. The results showed that the maximum temperature Tmax and temperature difference ΔT of the battery module under 1 C discharge rate could be reduced by 1.1°C and 0.92°C compared to the single liquid cooling. Comparing the LCP‐AFC with single air cooling, the Tmax and ΔT of the battery module under 4 C discharge rate could be reduced by 18.74°C and 2.71°C. The temperature uniformity of the battery module was not satisfied with the inlet temperature of the cooling liquid, which was lower than 15°C. The heat transfer performance was improved by adding Al, Cu, or Ag nanoparticles into the deionized water. Among them, Ag–water nanofluid had the most significant cooling effect. Parallel flow indicated better thermal performance than cross flow and counter flow. The developed cooling system of LCP‐AFC offers a new method to design lithium‐ion battery thermal management system for controlling temperature distribution of a battery module.

Thermal energy investigation of magneto-hydrodynamic nano-material liquid flow over a stretching sheet: comparison of single and composite particles

The foremost purpose of the current study is to examine the heat transmission characteristics of two-phase and hybrid phase rotating nanofluid flow in three dimension over the stretchable sheet in the applied magnetic field. The novelty of this work is that due to numerous applications it considers a new sort of nanofluid i.e. hybrid nanofluid. Water is utilized as base fluid while silver,Ag and molybdenum disulfide, MoS2 are used as nanoparticles in the current study. The nanofluid is rotating around the straight-up axis with a fixed angular speed ω∗. The resultant nonlinear partial differential equalities are transformed into ordinary differential equations via a resemblance transformation. The numerical results are obtained at Matlab by using the bvp4c technique. Rotation parameter increases while stretching ratio parameter decays the temperature transference rate. In this particular research, the temperature transmission rate of hybrid nanofluid Ag/MoS2-water was found higher than Ag-water nanofluid in the existence of the magnetic effect. The temperature transmission rates of hybrid nanofluid can be achieved higher by using a suitable combination of nanoparticles.

Heat Transfer Analysis of Nanostructured Material Flow over an Exponentially Stretching Surface: A Comparative Study

The objective of the present research is to obtain enhanced heat and reduce skin friction rates. Different nanofluids are employed over an exponentially stretching surface to analyze the heat transfer coefficients. The mathematical model for the problem has been derived with the help of the Rivilin–Erickson tensor and an appropriate boundary layer approximation theory. The current problem has been tackled with the help of the boundary value problem algorithm in Matlab. The convergence criterion, or tolerance for this particular problem, is set at 10−6. The outcomes are obtained to demonstrate the characteristics of different parameters, such as the temperature exponent, volume fraction, and stretching ratio parameter graphically. Silver-water nanofluid proved to have a high-temperature transfer rate when compared with zinc-water and copper-water nanofluid. Moreover, the outcomes of the study are validated by providing a comparison with already published work. The results of this study were found to be in complete agreement with those of Magyari and Keller and also with Lui for heat transfer. The novelty of this work is the comparative inspection of enhanced heat transfer rates and reduced drag and lift coefficients, particularly for three nanofluids, namely, zinc-water, copper-water, and silver-water, over an exponentially stretching. In general, this study suggests more frequent exploitation of all the examined nanofluids, especially -water nanofluid. Moreover, specifically under the obtained outcomes in this research, the examined nanofluid, Ag-water, has great potential to be used in flat plate solar collectors. Ag-water can also be tested in natural convective flat plate solar collector systems under real solar effects.

Numerical Analysis of Fluid Dynamics and Heat Transfer from Flow Over Square Cylinder Using Ag-Water Nanofluid

Numerical Analysis of Fluid Dynamics and Heat Transfer from Flow Over Square Cylinder Using Ag-Water Nanofluid

Numerical study of mixed convection and entropy generation of Water-Ag nanofluid filled semi-elliptic lid-driven cavity

In this study, laminar mixed convection of water/Ag nanofluid with volume fraction of nanoparticles φ = 0, 2, 4, and 6% and Grashof numbers Gr = 50,000, 150,000, 250,000 and 400,000 and Richardson numbers Ri = 0.1, 1, and 10 are simulated using finite volume method. Obtained results indicate that adding a higher volume fraction of nanoparticles at lower Richardson numbers leads to the enhancement of heat transfer and Nusselt number. Streamlines behavior in the cavity is under the influence of two main factors including lid-driven motion (which is the basic factor) and the viscosity of fluid (which transfers the fluid motion to bottom layers and affects the flow domain). Every factor stimulating the flow domain causes uniform temperature distribution in the cavity. The increase of Richardson number leads to the enhancement of lid-driven velocity, temperature penetration and a better mixture of fluid layers, and by increasing Grashof number; this issue can have a great effect on uniform temperature distribution.

Two-phase mixture simulation of the performance of a grooved helical microchannel heat sink filled with biologically prepared water-silver nanofluid: Hydrothermal characteristics and irreversibility behavior

• A novel heatsink with grooved helical microchannels is suggested. • Biologically synthesized water-Ag nanofluid is considered as the working fluid. • First and second law analysis of nanofluid flow inside the heatsink are evaluated. • Heatsink with staggered grooved helical channels has best first-law performance. • Grooving the helical channel entails an increment in the entropy generation. The present paper investigates the influence of using two grooved channel geometries on the hydrothermal performance of a helical microchannel heat sink. The results were compared with those obtained for the plain channel geometry. Based on the results, the highest flow mixing is observed for the staggered grooved configuration. Moreover, the convective heat transfer coefficient enhances by nearly 70% and 17% for the MCHS with the staggered and parallel grooved channels, respectively, as compared to that with the plain channel. The influence of Reynolds number ( Re ) escalation on the convective heat transfer coefficient is insignificant, while a 21% increase is obtained when NF concentration is increased from 0% to 1%. Furthermore, the increase of φ in the grooved configurations is more effective than that in the plain configuration. In addition, the lowest thermal resistance and temperature uniformity factors were obtained for the staggered grooved configuration. Besides, the parallel grooved configuration represents the highest frictional entropy generation rates among the three studied geometries due to the considerable reduction of the fluid flow cross-section area between the groove ribs. The highest heat transfer coefficient and pressure drop are associated with the staggered grooved configuration. For the plain, parallel grooved, and staggered grooved configurations, the increase of Re from 500 to 2000 escalates the NF pressure drop by 2730%, 4420%, and 4460%, respectively. Therefore, the highest performance evaluation criterion of more than unity was obtained for the MCHS with the staggered grooved channels for the studied range of Re (500–2000). The numerical analysis was also performed to evaluate the influence of groove pitch on the hydrothermal performance of the staggered groove channel for the pitch range of 0.15 mm to 0.75 mm. The results demonstrated that the highest PEC is associated with the groove pitch of 0.75 mm.

Thermal Management of Magnetohydrodynamic Nanofluid Within Porous C-Shaped Cavity with Undulated Baffle

The present work focuses on the Magnetohydrodynamic free convection heat of Ag–water nanofluid involved in a porous C-shaped enclosure equipped with an undulated baffle. Various thermophysical parameters are investigated through this specific configuration, such as Rayleigh number (), Hartmann number (), Darcy number (), porosity (), and nanoparticles concentration (). The calculations were carried out through the finite element method for Prandtl number . The novelty in this paper was the implementation of an inner baffle with a special shape inside the cavity instead of conventional ones and the definition of its optimal dimensions. The uniqueness of this work is that it overcomes the previous research gap by investigating the influence of the specific shape of the cold corrugated baffle on heat flux inside a C-shaped porous chamber. The obtained results show the favorable impact of increasing the thickness and the length of this undulated baffle on the heat transmission performance. However, the variation in the undulation number () presented a negligible impact.