Heat Transfer Dissipation Research Articles

Parity-time and anti-parity-time symmetries in heat transfer.

This perspective briefly reviews the recent developments of non-Hermitian parity-time and anti-parity-time physics in dissipative heat transfer systems, highlighting their potentials in novel functional thermal devices in the future.

Dissipative heat transfer on MHD micropolar hybrid nanofluid flow through infinite parallel squeezing plates

The hybrid nanoparticles suspended in an ethylene glycol water mixture are modeled as micropolar nanofluids. Studying the properties of such a mixture through a squeezing channel is vital in heat exchangers and as a cooling agent in producing sheets out of molten solids. The study aims to regulate the heat transfer rate through a hybrid nanofluid of carbon nanotubes and ferrous oxide nanoparticles immersed in ethylene glycol water. The motion of the fluid and the heat transfer with the plates are studied through the Navier-Stokes equation and the first law of thermodynamics by assuming that the base fluid has micropolar fluid properties. Apart from the usual viscous dissipation, heat dissipation due to the fluid’s micropolar nature is vigorously studied by solving the governing equations through a shooting technique with Runge-Kutta 4th-order algorithm. The results of the current study are compared against the ones with earlier studies as exceptional cases, and are very close. It is noticed that an increase in the micropolar viscosity naturally lowers the momentum in the radial direction and, at the same time, it enhances the axial momentum due to squeezing phenomena. Further, an escalating behavior is noticed in both temperature and microrotation, with an increase in micropolar parameters due to the squeezing force.

Numerical and statistical analysis of unsteady hydromagnetic hybrid nanofluid flow in a porous medium over an inclined disk with dissipative heat transfer

AbstractThe present analysis deals with the three‐dimensional radiative, convective hybrid nanofluid flow over a rotating and stretching inclined disk under the action of the applied magnetic field, Joule's heating, and viscous dissipation effects. The mathematical model considers nanoparticles graphene oxide (GO) and molybdenum disulfide (MoS) suspended in water as the base fluid within a Darcy medium. The cylindrical coordinate system is used to express continuity, momentum, and energy partial differential equations, out of which momentum and energy partial differential equations are transformed into ordinary differential equations using a suitable transformation method under the boundary‐layer approximation. The transformed equations are further solved using the spectral quasi‐linearization method. Graphical and numerical data are presented to investigate the behavior of velocity and temperature under various parameters and shape factors. The nature of fluid flow at the boundary wall is determined by tables of skin friction and the Nusselt number. Statistical analysis of the parameters for axial and tangential skin friction and the Nusselt number is performed using the quadratic regression model.

Investigation of dissipative heat transfer and peristaltic pumping on MHD Casson fluid flow in an inclined channel filled with porous medium

A theoretical investigation is performed for free convective peristaltic pumping of a Casson fluid through an inclined porous wavy channel. The flow is subjected to uniform magnetic field in the transverse direction. In addition, the energy equation contains porous and viscous dissipation effects. The governing flow problem is modeled for Casson fluid with the help of conservation laws of mass, momentum, and energy under the long wavelength assumption. Using a regular perturbation method, we obtained the analytical expressions for the axial velocity, temperature, pressure rise per one wavelength, and heat transfer rate. The consequences of various effects on the flow quantities are demonstrated in the form of graphical representations and discussed in detail. The findings reveal that the rise in the thermal Grashof number and permeability parameter leads to an increment in the velocity and thermal fields. The heat transfer rate strengthened when the Casson parameter and magnetic parameter were increased. The pressure rise exhibits an enhancing trend for the Brinkmann number and permeability parameter. Further, we observed a decreasing behavior on streamlines for increasing magnetic field strength. Moreover, the obtained findings are applicable to a variety of fields in the bioengineering and medical sciences, such as targeted drug delivery, heart-lung machines, MRI, cancer therapy, power conversion devices, and micromanufacturing processes.

Analysis of Entropy Generation on MHD Radiative Viscous-Ohmic Dissipative Heat Transfer Over a Stretching Sheet in a Chemically Reactive Jeffrey Nanofluid with Non-Uniform Heat Source/Sink Based on SQLM

We have examined the effect of entropy generation and nonlinear thermal radiation on magnetohydrodynamic (MHD) in Jeffrey nanofluid over a permeable stretching sheet with viscous-Ohmic dissipation and non-uniform heat source/sink. Brownian motion and thermophoresis effects have also been taken into account. The basic governing equations of the boundary layer flow are then solved numerically by the Spectral Quasilinearization method (SQLM). Various controlling physical parameters effects on velocity, temperature, concentration, entropy generation and Bejan number profiles are presented graphically. Results show that increasing the magnetic parameter, Brownian motion parameter, and thermophoresis parameter enhance the temperature profiles. Furthermore, the entropy generation profiles increase with space-dependent and temperature-dependent parameters, wall mass flux parameter, and chemical reaction parameter near to the sheet. In contrast, reverse trends are observed away from the sheet. Novelty of entropy generation is also provided to reflect the effects of several relevant physical parameters on the entropy generation rate and Bejan number.

Исследование величины аномалий теплового потока в тылу зон субдукции в зависимости от угла и скорости субдуцирующей плиты

The relevance of the material presented in this article is related to the identification of the dependence of the anomalous heat flux magnitude on the angle and velocity of lithospheric subduction, and assuming the constancy of the effective viscosity of the upper mantle material and the conductive mechanism of dissipative heat transfer. We analytically solved the equation of dissipative heat transport in a mantle wedge over a flatly subducting lithospheric plate on the basis of the method estimating the anomalous heat flux carried to the day surface from the mantle wedge in the rear of subduction zones. As a result, exemplified by Amur and Adriatic plates, for which the velocity of subduction is determined by modern geodetic methods (approximately 10 mm per year) and the angle of subduction — from seismological data (25–30 degrees), the obtained dependence of the anomalous heat flux on the angle and velocity of lithospheric subduction is proved valid. The previously unmeasured velocity of the Black Sea microplate subduction under the Crimea was estimated of 3 mm per year. With the obtained velocity of matter in the mantle wedge at the roof of the mantle, the upward conductive flow can provide the observed removal of heat and hydrocarbons from the mantle to the day surface and the formation of hydrocarbon deposits.

Entropy Generation and Regression Analysis of Magnetohydrodynamic Stagnation Point Flow of a Casson Fluid with Radiative and Dissipative Heat Transfer and Hall Effects

The phenomenon of heat transfer is prevalent in industries and has an extensive range of applications. However, mostly the discussion of heat transfer problems is limited to the study of the first law of thermodynamics, which deals with energy conservation. It is just restricted to the quantity of energy, not to its quality; i.e., there is no difference between the work (high‐grade energy) and the heat (low‐grade energy). A measurement of the degree of randomness of energy in a system is known as entropy. It is unavailable for doing useful work because work takes place only from ordered molecular motion. Even though many boundary layer models exist in the literature to investigate the flow and heat transfer of various fluids along a stretching surface, they have not yet been used at their maximum ability. The main motive of the current research is to discuss entropy generation or its minimization during heat transfer. This work presents an entropy generation analysis for the transient three‐dimensional stagnation point flow of a hydromagnetic Casson fluid flowing over a stretching surface in the existence of Hall current, viscous dissipation, and nonlinear radiation. The physical configuration of the present work is described in terms of partial differential equations (PDEs) of nonlinear nature. Furthermore, these PDEs are converted into ordinary differential equations by using some relevant similarity transformations. An efficient numerical method named as the spectral quasilinearization method (SQLM) is used to solve this model. The expression of the Bejan number and volumetric entropy generation rate is also computed. A parametric analysis, including the essential physical parameters, is performed to examine the influences of distinct flow parameters on the velocity profile, temperature profile, Bejan number, entropy generation number, and the coefficients of skin friction and the Nusselt number. In order to further insight into the emerging physical quantities of engineering interest, multiple quadratic regression models are used to estimate the coefficients of skin friction and heat transfer.

Assessment of Convective Heat Transfer Characteristics for Elliptical-Shaped Pin-Roughened Surface for the Jet Impingement Cooling

Abstract In a jet impingement cooling (JIC) system, the layout of the target surface and length of the jet holes can change both the flow field and the heat transfer characteristics. Elliptical-shaped pins (ESPs) with different heights and layouts on the target surface of the extended jet hole configurations were examined numerically in a jet impingement system. The ESPs were arranged in a staggered and circular form. Normalized nozzle length (Gj/Dj = 1.0, 2.0, 6.0) and normalized pin height (Hp/Dj = 0, 0.167, 0.417, 0.667) were investigated as geometric parameters. Also, the effect of different pin layouts (R1, R2, R3) on heat transfer dissipation was studied by changing the number of pin rows in particular configurations. A numerical model was developed and verified with experimental and numerical data from the literature. Numerical analyses were conducted with the shear stress transport (SST) k–ω turbulence model taking the boundary conditions into account under turbulent flow conditions (16,250 ≤ Re ≤ 32,500). Nusselt (Nu) numbers, pressure drop, and the thermo-hydraulic performance of the physical model were quantitatively researched to elucidate the underlying mechanisms of enhanced heat transfer by the ESPs. Results were compared with the orifice surface (Hp/Dj = 0 and Gj/Dj = 6.0). Results showed that area-averaged Nu number on the target wall increased up to 35.82% for Re = 16,250 by R2_Gj/Dj = 1.0 and Hp/Dj = 0.167 compared to the conventional JIC system. The performance evaluation criterion (PEC) was used to analyze the thermo-hydraulic performance of the examined physical models. According to the PEC values, the most feasible parameters for all Re numbers were R3_Gj/Dj = 1.0 and Hp/Dj = 0.167. Furthermore, increasing the number of pin rows in the channel also increased the uniformity of the local heat transfer distribution according to Nu contours.

Effect of Ohmic heating on magnetohydrodynamic flow with variable pressure gradient: a computational approach

ABSTRACT Ohmic heating, which significantly affects magnetohydrodynamic flow, is one of the exciting effects to be experienced. This study looks at the significance of Ohmic heating on two-dimensional flow and dissipative heat transfer of a viscous fluid over a flat surface. The mainstream flow is subjected to a pressure gradient and externally oriented inclined magnetic field. An implicit finite difference method has been used to obtain the convergent solutions and the graphical results have been obtained using MATLAB software. A positive correlation is found between temperature and viscous dissipation parameter. Further, the flow encountered higher resistance due to the magnetic field, which is more prominent when the magnetic field is normal to the flow direction .

Mass Transfer of a Thermally Radiative MHD Cattaneo-Christov Nanofluid between Two Stretchable Spinning Disks

The investigation on the impacts of magnetic field, thermal radiation, generation of heat and mass transfer in a porous-medium-embedded homogenous nanofluid flow between two stretchable spinning disks is crucial since spinning disks are prevalent in many engineering and technological applications. The objective of this research was to analyze the influences of these parameters using the Cattaneo-Christov heat flux model against the flow’s temperature, velocity and concentration profiles. Temperature profile is a decreasing function of thermal relaxation time parameter due to the particles require a longer period to transfer heat to the next particles. The rates of heat transfer at both spinning disks decrease as values of heat generation, Eckert number, Prandtl number, Brownian diffusion, thermophoresis diffusion and rotation ratio increase. The disks’ rates of mass transfer decrease with more thermophoresis diffusion, heat generation, heat transfer dissipation, and momentum diffusivity, but they increase with thermal radiation parameter. The current work attempts to include the transport profile of a Buongiorno’s nanofluid embedded in a Darcian porous medium between dual spinning disks with magnetic field, thermal radiation and generation of heat using the heat flux model of Cattaneo-Christov’s. Von Karman transformations are utilized to transform the nonlinear partial differential equations of fluid dynamics into coupled nonlinear ordinary differential equations (ODEs). These coupled ODEs are later solved by employing a shooting method with MATLAB bvp4c algorithm. All numerical evidences from this investigation are conferred through tables and figures after validation of present computations.

On analysis of magnetized viscous fluid flow in permeable channel with single wall carbon nano tubes dispersion by executing nano-layer approach

The prime motive of this pagination is to adumbrate attributes of water-based hybrid nanoliquid flow with dispersion of single wall carbon nanotubes. An innovative thermal conductance model containing the aspects of nanolayer formation along with shape and size of inserted particles is obliged. Flow transport mechanism is addressed mathematically in the form Navier Stokes equations with magnetization. In addition, heat and mass transport mechanism is manipulated by considering the impression of viscous dissipation and chemical reactions. Walls of channels are assumed to be porous in order to examine the phenomenon of suction and injection. Mathematical formulation of problem is represented in view of ODE’s and simulated computationally by Keller Box scheme. Subsequently, Newton method is utilized to solve system of nonlinear equations. Results are revealed through graphs and tables showing behavior of associated momentum, temperature and concentration profile against involved parameters. Quantities of engineering interest like wall drag coefficient, heat and mass fluxes are computed. Credibility of work is shown by creating match with existing study and an excellent agreement is found. After thorough analysis it is determined that heat flux increases with induction of single wall carbon nanotubes in base liquid. It is also manifested that thermal conductance of base fluid enriches with increase in thickness of nanolayer and radius of particles. In addition, positive trend in skin friction and heat flux coefficients is measured against elevation in nanoparticle volume fraction. Opposite behavior in velocity and temperature distributions against all flow variables near upper and lower walls of channel is depicted due to provision suction and injection wall velocities. Due to consideration of viscous dissipation heat transfer rate with in the flow domain reduces. By increasing Reynold number concentration distribution diminishes due to dominant effect of inertial forces. Decline in momentum distribution against Hall current parameter is adhered. Uplift and decrement in temperature distribution is manifested against heat source and sink parameters respectively.

Unsteady absorption flow and dissipation heat transfer over a non-Newtonian fluid

The current research explores an unsteady Casson fluid flow through a stretching sheet with a thermal radiation effect. The influence of heat absorption/generation, viscous disputation and Joule heating is also incorporated. The governing partial differential equations of the flow problem are reduced into boundary layer regimes, which are then transformed using similarity variables into ordinary differential equations. The results are conducted graphically to present the feature of the different parameters in the problem. The physical quantities are tabulated and observed. It is examined that the velocity field is scaled back for thicker values of . Furthermore, higher values of increase the thermal layer thickness.

Two-way fluid-structure interaction study of twisted tape insert in a circular tube having integral fins with nanofluid

This work deals with fluid-structure interaction (FSI), one of the emerging areas of numerical simulation and calculation. This research shows a numerical study investigating heat transfer enhancement and fluid-structure interaction in a circular finned tube by using alumina nanofluid as a working fluid with a typical twisted tape that has a twisting ratio of 1.85. The studied nanofluid volumes of fraction are φ=0, 3, 5 % under conditions of laminar and turbulent flow. The solution for such problems is based on the relations of continuum mechanics and is mostly done with numerical methods. FSI occurs when the flow of fluid influences the properties of a structure or vice versa. It is a computational challenge to deal with such problems due to complexity in defining the geometries, nature of the interaction between a fluid and solid, intricate physics of fluids and requirements of computational resources. CFD investigations were made based on the numerical finite volume techniques to solve the governing three-dimensional partial differential equations to get the influence of inserted twisted tape and concentration of nanofluid on heat transfer enhancement, friction loss, average Nusselt number, velocity profile, thermal performance factor characteristics, and two-way interaction in a circular tube at laminar and turbulent flow. The governing continuity, momentum and energy transfer equations are solved using Ansys Fluent and Transient Structural. The simulation results show that the deformations of two-way coupling fluctuate from side to side, with 0.004 mm, as maximum amplitude, located at the typical twisted tape center. Heat transfer dissipation improved by adding fins and as Reynolds numbers increase the heat transfer behavior increases.

Stagnation Point Flow in Copper Nanofluid over Slippery Cylinder with Viscous Dissipation

This study investigates the heat transfer dissipation on stagnation point flow over a slippery stretching/shrinking cylinder in a copper nanofluid by considering the effect of viscous dissipation. A system of nonlinear partial differential equations is modelled and transformed into ordinary differential equations using similarity transformations. The governing equations with the corresponding boundary conditions are analysed numerically using a bvp4c solver in MATLAB. The solutions are found to be dependent on the Eckert number and slip parameters. The results are represented by the velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number. Dual solutions are observed for the shrinking cylinder in the presence of Eckert number. Velocity profile and skin friction coefficient consistently increase while temperature profile increases initially and then decreases with the increase of slip parameter for both first and second solutions. Moreover, the presence of copper nanoparticles reduces the thermal boundary layer thickness. This research can be enhanced by using hybrid nanofluids to further improve the heat transfer.

Entropy generation and dissipative heat transfer analysis of mixed convective hydromagnetic flow of a Casson nanofluid with thermal radiation and Hall current

The present article provides a detailed analysis of entropy generation on the unsteady three-dimensional incompressible and electrically conducting magnetohydrodynamic flow of a Casson nanofluid under the influence of mixed convection, radiation, viscous dissipation, Brownian motion, Ohmic heating, thermophoresis and heat generation. At first, similarity transformation is used to transform the governing nonlinear coupled partial differential equations into nonlinear coupled ordinary differential equations, and then the resulting highly nonlinear coupled ordinary differential equations are numerically solved by the utilization of spectral quasi-linearization method. Moreover, the effects of pertinent flow parameters on velocity distribution, temperature distribution, concentration distribution, entropy generation and Bejan number are depicted prominently through various graphs and tables. It can be analyzed from the graphs that the Casson parameter acts as an assisting parameter towards the temperature distribution in the absence of viscous and Joule dissipations, while it has an adverse effect on temperature under the impacts of viscous and Joule dissipations. On the contrary, entropy generation increases significantly for larger Brinkman number, diffusive variable and concentration ratio parameter, whereas the reverse effects of these parameters on Bejan number are examined. Apart from this, the numerical values of some physical quantities such as skin friction coefficients in x and z directions, local Nusselt number and Sherwood number for the variation of the values of pertinent parameters are displayed in tabular forms. A quadratic multiple regression analysis for these physical quantities has also been carried out to improve the present model’s effectiveness in various industrial and engineering areas. Furthermore, an appropriate agreement is obtained on comparing the present results with previously published results.

Heat transfer analysis in compact heat exchanger with fibre reinforced plate

Due to their lightweight and ease of manufacturing, fibre-reinforced composites are replacing metals in many heat exchanger applications. However, their heat transfer dissipation performance is not investigated in detail. This paper aims to study experimentally the heat transfer performance of fins made from fibre reinforced composites in compact heat exchangers. Thin fins were manufactured from reinforced fibre composites by the hot pressing technique. The fins have dimensions of 11.5 cm wide and 11.5 cm long. Five different airflow velocities with fixed water flow rates were considered in the analysis. The temperature distribution inside the tube was measured at eight different points using a K-type thermocouple.The results showed that the water temperature at the outlet section was the highest at the lowest airflow velocity. Moreover, the air-side heat transfer coefficient increased along the tube length at all airflow velocities. The comparable heat transfer performance results make the fibre reinforced fins a good choice in the compact fin-and-tube heat exchanger.

Thermal management system with nanofluids for hybrid electric aircraft battery

Electric aircraft should be used more intensively due to the increase in energy consumption and the decrease in reserves of fossil fuels. Batteries are also an important factor in the development of electric aircraft. One of the most important parameters for the effective operation of batteries is the evaluation of heat dissipation. The even distribution or reduction of the heat generated during the operation of lithium-ion batteries extends the life of the batteries and ensures the safety of electric aircraft. In order to improve heat transfer dissipation in batteries in hybrid electric aircraft, it is necessary to increase the thermal conductivity of the coolant. For this reason, it has been suggested that solid particles with high thermal conductivity should be added to the coolant. In the present study, different battery thermal management strategies are suggested. To research the effect of nanofluids for thermal management in lithium-ion batteries, the study included two different base fluids (water and ethylene glycol) and three different volumetric fractions (1%, 2%, and 5%) of nanoparticle (Fe2O3) were added to these fluids. While the study was evaluated at four different discharge rates (1.0, 1.5, 2.0, and 2.5), the inlet velocities and temperature of the fluid were also changed. The cooling performances for 15 batteries module were examined and the simulation results showed that the nanofluid-based coolant could keep the temperature of the module at the desired value. As a result of the analysis, water was found to be the best nanofluid coolant parameter because it had a higher thermal conductivity than ethylene glycol. When the C value of the battery module was increased, that is, when the module was charged faster, its temperature increased. It was seen that the module was cooled better when the volume fraction of nanofluids and the speed of the refrigerant were increased.

Effect of Reynold’s number on effective heat transfer dissipation of braking system

Reynold’s number is an effective parameter in the thermal and computational fluid dynamics analysis of a braking system. Laminar, forced and normal convection is there for a braking system due to variation in Reynold’s number. Due to a change in Reynold’s number, the Heat convection parameter is affected for a disc brake, and temperature variation is observed. Stainless Steel 410 material is used for brake disc and due to variation of heat convection , situations Laminar and forced convection has been considered and temperature variation in all the situations has been concluded through Thermal & CFD heat transfer analysis using ANSYS. Fine Meshing has been carried out during the thermal and CFD heat transfer analysis for better efficiency in results. Mathematical calculations have been carried out using MATLAB. Vehicle design parameters have been taken into the consideration to generate efficient heat flux and heat convection for the disc brake to achieve an efficient braking system for the vehicle.

Effect of Viscous Dissipation in Heat Transfer of MHD Flow of Micropolar Fluid Partial Slip Conditions: Dual Solutions and Stability Analysis

In this study, first-order slip effect with viscous dissipation and thermal radiation in micropolar fluid on a linear shrinking sheet is considered. Mathematical formulations of the governing equations of the problem have been derived by employing the fundamental laws of conservations which then converted into highly non-linear coupled partial differential equations (PDEs) of boundary layers. Linear transformations are employed to change PDEs into non-dimensional ordinary differential equations (ODEs). The solutions of the resultant ODEs have been obtained by using of numerical method which is presented in the form of shootlib package in MAPLE 2018. The results reveal that there is more than one solution depending upon the values of suction and material parameters. The ranges of dual solutions are S ≥ S c i , i = 0 , 1 , 2 and no solution is S < S c i where S c i is the critical values of S . Critical values have been obtained in the presence of dual solutions and the stability analysis is carried out to identify more stable solutions. Variations of numerous parameters have been also examined by giving tables and graphs. The numerical values have been obtained for the skin friction and local Nusselt number and presented graphically. Further, it is observed that the temperature and thickness of the thermal boundary layer increase when thermal radiation parameter is increased in both solutions. In addition, it is also noticed that the fluid velocity increases in the case of strong magnetic field effect in the second solution.

Physical aspects of Darcy–Forchheimer flow and dissipative heat transfer of Reiner–Philippoff fluid

The main focus of the present research work is to elaborate the Reiner–Philippoff fluid flow over a stretching sheet along with thermal radiation effect. A Darcy–Forchheimer medium was imposed and a linear stretching surface was used to generate the flow. Application of appropriate transformation yields nonlinear ordinary differential equation through nonlinear Navier–Stokes equations and solved by Runge–Kutta–Fehlberg shooting technique. Importance of influential variables such as velocity and temperature was elaborated graphically. It is envisaging that the boost up values of γ declines the both velocity and temperature profiles.