Wavy Channel Research Articles

Comment on the paper “Entropy analysis in the Rabinowitsch fluid model through inclined Wavy Channel: Constant and variable properties, Yu-Ming Chu, M. Nazeer, M. Ijaz Khan, W. Ali, Z. Zafar, S. Kadry, Zahra Abdelmalek, International Communications in Heat and Mass Transfer 119 (2020) 104980”

Some errors exist in the above paper.

On the effects of surface waviness upon catalytic steam reforming of methane in micro-structured reactors - a computational study

The effects of wavy channels upon steam methane reforming in catalytic micro-structured reactors, using Nickle as the catalyst, are investigated numerically. Laminar, three-dimensional models of reacting flows, with heterogeneous chemistry, are developed and applied to micro-structured reactors with different wave patterns on their internal walls. It is observed that introduction of surface waves on the walls of reactor, can significantly alter production and consumption of H2 and CH4. This is shown to be due to large fluctuations in convective mass and heat transfer, induced by the surface waviness. In particular, it is shown that separation and reattachment of concentration and thermal boundary layers and the subsequent modifications in Sherwood and Nusselt number can significantly affect the catalytic processes over the walls of reactor. A major local intensification of catalytic processes is observed where Sherwood and Nusselt number are maximised. Similarly, the catalytic process becomes highly inefficient in places with minimal Sherwood (and Nusselt) number. The analyses further reveal that a strategic discrete coating of wavy walls with the catalyst can substantially improve the performance of microstructure. For example, by coating only 25% of the surface area of wavy walls, CH4 conversion rate and selectivity per coated surface area increase by 459% and 308% compared to those of an equivalent fully coated straight channel. This implies the possibility of developing highly efficient and cost-effective catalytic micro-reactors for production of hydrogen from methane.

Heat transfer enhancement in cold plates with wavy channels via free-shape modeling and optimization

The objective of this study is to improve heat transfer performance of cold plates with wavy channels typically used in Battery Thermal Management Systems (BTMSs). The means of enhanced design flexibility based on parametric modeling allows for the free construction of wavy geometry in terms of amplitudes, wavelengths, waveforms, and cross-sections. The fixed dimensions are “liberated” into these four degrees of freedom, which helps to find the optimized wavy structures with the superior cooling performance. Based on the proposed free-shape modeling framework, the Horizontal Wavy Channel (HWC) and Radial Wavy Channel (RWC) are constructed, and these single channels can be considered as the basic structure of cold plates. One of the most popular evolutionary algorithms, NSGA−II, is utilized to optimize these two types of channels. The average temperature (overall thermal performance) and root mean square temperature (temperature uniformity) of top and bottom surfaces of cold plates are specified as the objective functions. In addition, to better verify the validity of the proposed method, empirical-based uniform HWC (UHWC) and RWC (URWC) are given as further comparisons. Based on the obtained Pareto front and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method, when the weight coefficients of the two thermal performance indicators are set to 0.5:0.5, the best compromised solutions are obtained: VHWC−22 for HWC and VRWC−30 for RWC. The results further show that the ranking of excellent overall thermal performance is VHWC−22 > URWC >≈ VRWC−30 > UHWC, while the ranking of excellent temperature uniformity is VRWC−30 > VHWC−22 > URWC > UHWC. Obviously, the variable wavy channels are generally superior the uniform wavy channels in terms of thermal performance. This work provides a guideline for the design of wave structures that can be used not only in cold plates but also in heat sink with fins, heat exchangers, and other components with wave structures.

Theoretical investigation of heat transfer analysis in Ellis nanofluid flow through the divergent channel

Nanofluid flow with heat transfer is investigated in this article. Ellis fluid model of non-Newtonian fluid features is treated as physiological fluid in a complex divergent wavy channel. Thermophysical properties of blood and gold are used to form the nanofluid. The single-phase model is taken into account for the mathematical formulation of the nano-suspension. Long wavelength approximation and assumption of low Reynolds number are applied to obtain the governing differential equations of heat mass transfer. A closed-form solution is achieved by following some cumbersome mathematical manipulations. The Poisson–Boltzmann differential equation is incorporated to derive anelectrochemical potential of ions for the electro-osmotic flow (EOF). Numerical data has also been computed against the most prominent contributors and found to be in complete adherence with the existing literature for the limiting case. It is inferred from the visual graphics that the convection of nanofluid rises initially due to the flexibility of the channel for additional introduction of nano species up to 20%. However, the case is vice versa for the region 1<x<1.5. The variation of Brinkman number greater than one (Br>1) outpaced the conduction of heat produced by viscous dissipation for the domain. Heat transfer rate diminishes which results in cooling-effects on the system. Enlarge boluses resulting from electro-osmotic parameters (UHS=3) indicate strong resistive forces.

Thermally progressive Particle-Cu/Blood peristaltic transport with mass transfer in a Non-Uniform Wavy Channel: Closed-form exact solutions

The motivation behind writing the current article is to mathematically study the thermally driven transport of solute particles (measured in micro to nano meters) suspended in blood in an Esophagus mathematically taken as a non-uniform channel. The aim of the present study is to see the effects of solute particles with blood and nanoparticles in Esophagus to see its application in drug delivery and biomedical engineering etc. It also has many applications in microscale phenomena in physiology. Here blood is taken as a base fluid and nanofluid is prepared by the suspension of copper oxide nanoparticles in blood. Copper oxide is extremely useful in the medical domain for drug delivery and cancer treatment. To further study the impact of nanomedicine delivery we considered copper nanoparticles embedded in blood along other small sized solute particles. The mathematical formulation is performed in a rectangular coordinate system and constitutive flow equations are linearized by the implementation of approximations of low Reynolds number and large wavelength. The exact solution of reduced coupled and nonlinear set of equations for fluid particle velocity, temperature and fluid-particle composition profiles is computed through Mathematica while pressure rise is calculated by applying numerical integration. The effect of notable emerging parameters is discussed through graphs. It is observed that velocity rises with an increase in suspension and Casson fluid parameter, whereas opposite results are observed for temperature distribution. Nanoparticles volumetric fraction contribute to decelerating fluid flow and upsurge temperature. Schmidt number influences the fluid-particle composition by lessening it. PACS number: 47.10. A−; 47.35.Pq; 47.85.-g.

Performance and mass transfer evaluation of PEM fuel cells with straight and wavy parallel flow channels of various wavelengths using CFD simulation

Polymer electrolyte membrane fuel cells (PEMFC) have the potential to replace conventional fossil fuels. The flow channel is a key part of the PEMFC that facilitates reactant mass transfer into the gas diffusion layer, catalyst layer, and membrane. Overall performance of the PEMFC mostly depends on the efficient mass transfer, pressure drop, and water management within this channel. In the straight channel mass transfer occurs by diffusion while in the wavy channel mass transfer occurs through convection. In this study, the performance and mass transfer evaluation of a PEMFC with a straight flow channel and wavy flow channels of different wavelengths (λ = 4, 4.8, and 6) were compared using a commercial solver (STAR-CCM+16.04). The simulation results were validated experimentally and the results were in good agreement. Comparison of the simulation results established that the mass transfer through diffusion and convection was more enhanced in the case of wavy channels.

Performance improvement of air-based solar photovoltaic/thermal collectors using wavy channels

The rise in the temperature of photovoltaic (PV) cells leads to a great reduction in their power output; therefore, having a cooling mechanism is critically important to keep the cells of practical benefit in hot climates. The use of wavy surfaces for effective cooling of PV cells seems very promising due to an increased turbulence intensity, generating secondary flows, and improved mixing fluid flows, and has never been studied before. Thus, this study numerically examines the impact of wavy channels with different wavelength (λ), amplitude (α) ratios, and the Reynolds number to reach an optimal geometry for the wavy channel utilized in PV/T collectors using ANSYS CFX. For this purpose, the Reynolds-averaged Navier-stokes equations are applied and the SST k-ω turbulent model is utilized. The results prove the strong impact of the wavy channels where a channel with wavelength & amplitude ratios of 0.1 and 1 has the most increase in the overall efficiency by 20.41% enhancement compared to conventional collectors. In addition, the highest increase in the Nusselt number is 69.7% at λ = 2 and α = 0.2 compared with the smooth channel. At α = 0.3 and λ = 3, the electrical efficiency can be enhanced by up to 1.66% at Re = 40,000.

Darcy flow of unsteady Casson fluid subject to thermal radiation and Lorentz force on wavy walls: Case of slip flow for small and large values of plastic dynamic viscosity

This article describes the evolution of the velocity slip and heat transfer effects on the magnetohydrodynamic oscillatory flow of Casson fluid in a wavy channel immersed in a porous medium in the presence of thermal radiation. The Casson fluid model is used to describe non-Newtonian fluid behaviour. Analytical solutions to the dimensionless governing equations are compared to the numerical outcomes produced by MATLAB's built-in numerical solver, bvp4c. The effect of various physical parameters on momentum and energy profiles of the Casson fluid is analysed. This report also examines a parametric analysis illustrating the impact of the Nusselt number and Casson parameter. Increased velocity fields result from higher values of the thermal radiation and Casson-Viscous parameters. When thermal radiation increases, the impact of thermal diffusivity and temperature increases, and the Prandtl number suppresses the temperature distribution. Furthermore, one slip parameter decreases the velocity field while the other increases fluid velocity. For various values of viscous and radiation parameter, the variations for skin friction coefficient and Nusselt number occur periodically because of the asymmetric wavy motion. A comparative study is carried out to characterise Newtonian and non-Newtonian fluid behavior by analyzing the velocity for β – small (non-Newtonian fluid) and β – large (Newtonian fluid) values of plastic dynamic viscosity using linear slope regression analysis.

A lignins based MHD hybrid nanofluid flow analysis by using an ionic Poisson-Boltzmann and Nernst-Planck equations in a wavy channel

This exploration deals with the interaction of inclined MHD peristaltic transport of lignin based hybrid nano-fluid flow in a wavy microfluidic inclined channel. The channel is filled with lignin based hybrid nano-fluid Mo S 2 - S i O 2 . Both the left and right walls are kept at uniform temperature having wavy shape. Impact of zeta potentials at the left and right walls are examined. The governing equations are solved for hybrid nanofluid Mo S 2 - S i O 2 by utilizing RK-4 based shooting method. Influence of engrossed parameters on the flow characteristics has been discussed via graphs. Range of engrossed parameters are taken as M = 0.1 , 1 , 1.4 . n = 10 , 10.5 , 11 . ϕ 1 = ϕ 2 = 0.001 , 2.5 , 2.7 . ξ 1 = ξ 2 = - 0.12 , - 0.13 , - 0.14 . . Based on numerical experiments, it is concluded that the velocity profile is significantly affected by nanoparticle volume fraction parameter. Moreover, the inclined magnetic parameter retards the motion of lignin based hybrid nanoliquid.

Numerical study of heat transfer of wavy channel supercritical CO2 PCHE with various channel geometries

Numerical study of heat transfer of wavy channel supercritical CO2 PCHE with various channel geometries

Optimization of bifurcating channel cooling system for double inclined conductive panel system under inclined magnetic field

A novel cooling system with wavy branching channels is proposed considering nano-enhanced magnetic field effects for thermal management of double inclined conductive panels. Thermal performance assessment is conducted by varying Reynolds number (250≤Re≤1000), Hartmann number (0≤Ha≤400), magnetic field inclination (250≤γ≤1000), amplitude (0≤Af≤0.4) and wave number (1≤Nf≤12). As the cooling fluid, water with Ag–MgO hybrid nanoparticles is considered. Temperature drops of 4.5 °C and 2.6 °C are obtained with the highest Re for left inclined panel (p1) and right inclined panel (p2). As the vortex distribution is highly affected for the wavy branching channels by the magnetic field strength, its impact on the cooling performance for p1 and p2 are different. It shows a favorable impact for panel p2 while average Nusselt number (Nu) increments become 10% and 6.3% when using flat and wavy branching channels at the highest magnetic field strength. For panel p1, varying inclination of magnetic field results in average surface temperature drop of 1.6 °C for wavy channel. The optimum value of wave number in the corrugated branching channel is Nf=2 for achieving the highest cooling performance while higher amplitudes of corrugation has favorable impacts on the cooling for each of the panels. As compared to un-cooled panel configuration, utilization of flat branching channel with nano-enhanced magnetic field results in 47.4 °C and 48.9 °C surface temperature drops for panels p1 and p2. Optimization based on COBYLA is utilized to achieve additional temperature drops as compared to parametric computational fluid dynamics. The optimum values of (Ha, γ, Af) are obtained as (40, 89, 0.04) at Re=100 and (40, 60.8, 0.0038) at Re=1000. The proposed single cooling method with wavy branching channel under nano-enhanced magnetic field can be used and further developed for effectively cooling of photo-voltaics with inclined arrangement, electronic cooling and many other heat transfer devices.

Heat transfer performance of thermoelectric cooling integrated with wavy channel heat sink with different magnetic distances

AbstractThermoelectric cooling (TEC) reverses the electrical energy to temperature caused by the Peltier effect, where a temperature difference occurs between two conductors, that is, hot and cold junctions. This article presents the enhanced heat transfer of a TEC module using a TEC1‐12710 model integrated with a wavy channel heat sink using ferrofluid as a coolant under continuous and pulsating flows, where the differences in the distance of the magnetic field are considered. Square permanent magnets measuring 30 mm × 20 mm × 4 mm (width × length × height) are used to transmit a magnetic field to the heat sink and then tested under a magnetic distance of 10–30 mm. The test is performed at a water flow rate from 0.0083 to 0.028 kg/s and supplied with a constant TEC voltage of 12 V. By applying a magnetic field to the TEC module with a magnetic distance of 20 mm and a ferrofluid concentration ratio of 0.015%, the cooling efficiency increases by approximately 18.64%. Hence, using pulsating flow may improve thermal efficiency by approximately 23%. The results show an exponential increase in the cooling efficiency when both passive and active cooling techniques are used.

Heat transfer analysis of pulsating nanofluid flow in a semicircular wavy channel with baffles

Heat transfer analysis of pulsating nanofluid flow in a semicircular wavy channel with baffles

Comparative study on different cooling techniques for photovoltaic thermal management: Hollow fins, wavy channel and insertion of porous object with hybrid nanofluids

The present work considers performance of different cooling methods applicable to photovoltaic (PV) panels. Hollow fins and two different channel cooling systems are considered. Flat and hollow fins types are used while cooling channels with wavy wall and with porous layer insert are compared. Effects of different fin numbers (between 2 and 16), hollow fin radius (between 0.8h and 3.2h, h-panel height), Reynolds number (between 100 and 500), wavy channel amplitude (between 0.01H and 0.5H, H-channel height), porous insert permeability (Darcy number between 10−6 and 10−1), porous layer size (between 0.1L and 0.7L, L-channel length) and nanoparticle volume fraction (between 0 and 0.02) on the cooling performance are numerically assessed. When nanofluid is used in the cooling channels, additional improvements in the cooling performance are obtained while temperature drop of 2.5 °C is achieved at the highest loading. When different cooling systems are compared, channel cooling with porous layer and wavy walls provide the highest cooling performance followed by hollow fin and flat fin systems while 37.6 °C , 37 °C, 33.6 °C and 29 °C temperature drops are obtained as compared to reference panel case without cooling system. When compared to flat fins, hollow fins perform better and additional temperature drop of 8.5 °C can be obtained by using 16 number of fins. It also provides a lightweight design as less material is used. Artificial neural networks are successfully used for performance estimation of wavy cooling channel system with 15 neurons in the hidden layer. The outcomes of this work is useful in further optimization and system development of PV cooling technologies as the need for thermal management in renewable energy sources is increasing due to the energy cost and environmental side concerns.

Connective and magnetic effects in a curved wavy channel with nanoparticles under different waveforms

Abstract The present study describes the peristaltic flow of Jeffrey fluid with nanomaterial bounded under peristaltic waves in a curved channel. Silver (Ag) is the nanomaterial used for this purpose, and base fluid is water. The diversity of peristaltic waves is captured under four different wave profiles traveling along the curved channel. The consequences of heat generation and mass concentration are also taken. The problem is modeled under physical laws and then simplified using the lubrication technique. The obtained system is sketched in graphs directly using a numerical scheme. The physical outcomes of involved parameters on axial velocity, temperature variation, concentration profile, and streamline patterns are discussed in the last section.

Numerical investigation of thermo-hydraulic features of viscoplastic flow in wavy channels

In the present work, the thermo- hydraulic characteristics are studied for a laminar viscoplastic flow through raccoon and serpentine type wavy channels. The results are presented by varying Bingham number (Bn), power-law index (n), Reynolds number (Re), dimensionless amplitude, and wave number in the physically justified ranges. It is found that the size of the recirculatory zone decreases with Bn and the zone disappears at the higher Bn values. The topology of the yielded-unyielded region highly depends on the geometry and the range of Bn. Moreover, the value of average Nusselt number decreases with n. With the increase in Bn, average Nusselt number gradually decreases up to a critical Bn value and then increases sharply at higher Bn values. Interestingly, the wavy channel is only advantageous at smaller Bn values up to a critical limit. The variation of performance factor (PF) strongly depends on the combined effect of rheological and geometrical parameters. Besides, results for raccoon and serpentine channels are highly dependent on the ranges of amplitude, wave number, Bn, and n.

Hybrid-nanofluid Flow through Partially Porous Wavy Channels: Thermo-hydraulic Performance and Entropy Analysis

Comprehensive numerical simulations are made to examine the combined effect of three distinct passive techniques: partial porous insert, corrugated walls, and hybrid nanofluid on thermo-hydraulic properties and entropy generation of three different wavy channels (triangular, sinusoidal, and trapezoidal) for the first time. The finite element method is used, and the simulations are performed considering Ag-TiO2-Water hybrid nanofluid (0 to 4%) as a coolant for Reynolds number range from 5 to 500 and Darcy number, 10−6. The present study will be helpful in designing and establishing a viable heat exchanging device from both the first law and second law of thermodynamics perspectives with maximum performance. It is demonstrated that the insertion of porous media between the corrugated walls enhances the thermal performance with simultaneous increment in pressure losses. It is observed that the trapezoidal channel is founded to be viable with a performance factor higher than 1 for a given range of Reynolds number, unlike the other two channels, which are viable only for higher Reynolds number. Therefore, the trapezoidal channel performs best with maximum enhancement in thermal performance by 90%. Also, from entropy generation analysis, it is shown that all three channels are thermodynamically advantageous from a second law perspective but only for low values of Reynolds number.

Effect of Hall Currents on Transient Convective Heat and Mass Transfer Flow of a Viscous Fluid in a Vertical Wavy Channel with Tranveling Thermal Waves

Effect of Hall Currents on Transient Convective Heat and Mass Transfer Flow of a Viscous Fluid in a Vertical Wavy Channel with Tranveling Thermal Waves

Numerical analysis of heat transfer and flow characteristics of supercritical CO2-cooled wavy mini-channel heat sinks

In today's world, thermal management in the components of new electronic and electromechanical technologies has become one of the most critical challenges in this realm. Generally, there is a high heat flux generating part in these instruments, so a robust heat dissipation or cooling system is required to guarantee their reliability and lifetime. Recently, miniature heat sinks have attracted the attention of many researchers, and the performance of air- and liquid-cooled heat sinks having wavy miniature channels has frequently been investigated. However, the heat transfer and flow characteristics of these cooling systems utilizing critical or pseudocritical carbon dioxide (CO2) as the coolant have not been investigated yet and are still an unclear subject. To fulfill this gap, 3D simulations are carried out to scrutinize the thermal and hydraulic characteristics of CO2 flow inside a wavy mini-channel heat sink at a uniform heat flux of 1000 kW m−2. This study also aims to explore the effects of specific design factors, including wave amplitude (wa) and wavelength (wl), at different inlet temperatures (from 305 to 310 K) and mass fluxes (500–2000 kg m−2 s−1) of the CO2 flow. The simulations start with the validation of the numerical results with the available experimental data, in which the deviations lie within ±2%. The results endorse that replacing the straight mini-channels with the wavy ones can enhance the thermal performance of the heat sink by an average of 1.86 times associated with an average pressure drop increment of 1.58 times. The maximal heat transfer coefficient of 8.58 times is obtained at the lowest inlet temperature of 305 K, whereas the maximal pressure drop of 5.65 times is observed at the highest inlet temperature of 310 K. The results suggest that larger wave amplitudes and smaller wavelengths contribute to the larger heat transfer coefficient values. However, these factors become less influential when the inlet temperature increases. Imposing a lower inlet temperature can significantly improve the overall performance. A maximal performance index of 4.41 is obtained for a model with wa = 1.0 and wl = 5 mm at the inlet temperature of 305 K.

Effects of Asymmetric Channel on the Convective Heat Transfer: A Computational Study

In the fields of engineering, especially in the heat transfer area, the contribution of the fluid flows through different channels is remarkable. Among the different available shapes in the channel, the sinusoidal wavy channels are considered more efficient in the heat transfer areas such as cooling of electronic devices, boilers, biomedical applications, etc., due to their increased recirculation capability of mixing the flowing fluids - which increases the heat transfer performance, consequently. The optimization of channel design and modelling has been an engineering problem in recent years. In this research, flat, symmetric sinusoidal, and asymmetric sinusoidal channels were designed - using ANSYS 2020 - to investigate the effects of channel shape, amplitude, and aspect ratio of sinusoidal wavy walls on the overall heat transfer performance. Several designs have been considered in the present study at different Reynolds numbers and different aspect ratios, keeping the wall temperature as constant. The results of this study exhibit that at an aspect ratio of 0.4, the asymmetric channel shows the highest heat transfer effect due to increased recirculation tendency.