Increase In Average Nusselt Number Research Articles

A hybrid scheme of single relaxation time lattice Boltzmann and finite volume methods coupled with discrete ordinates method for combined natural convection and volumetric radiation in an enclosure

This paper is focused on the application of hybrid Single relaxation time lattice Boltzmann and finite volume methods in conjunction with discrete ordinates method to simulate coupled natural convection and volumetric radiation in differentially heated enclosure, filled with an absorbing, emitting and non-scattering gray medium. In this work, the velocity and temperature fields are calculated using lattice Boltzmann and finite volume methods respectively, whereas the radiative term is computed by the discrete ordinates method. This study is carried out for Pr = 0.71, a Rayleigh number range of 103 ≤ Ra ≤ 106, an optical thickness with values 0 ≤ τ ≤ 100, a Planck number ranging in 0.001≤ Pl ≤ 100 and an aspect ratio varying between 0.5 ≤ Ar ≤ 2. Results are presented in terms of streamlines, isotherms, velocity profiles and average Nusselt number. Based on the obtained results, it can be concluded that the presence of volumetric radiation is noteworthy. Its effect, as a function of Rayleigh number and the radiative properties, yields significant changes on the behavior of streamlines and isotherms. In the taller enclosure, the increase of average total Nusselt number with increasing Rayleigh number is less significant than that in the case of the shallow enclosure.

Two- and three-dimensional comparative study of heat transfer and pressure drop characteristics of nanofluids flow through a ventilated cubic cavity (part II: non-Newtonian nanofluids under the influence of a magnetic field)

In this paper, we study numerically the incompressible laminar mixed convection flow of Zinc Oxide nanolubricants in ventilated cavities (2D and 3D cavities), under the influence of a uniform magnetic field at various inclination angles. The ventilation is assured by two openings of the same size, located at the vertical walls, where the cold nanofluid enters through the opening, located at the top of the left wall, and exits through the second, located at the bottom of the right wall. All walls are considered hot except the lateral walls of the 3D configuration which are adiabatic. The non-Newtonian nanofluid (nanolubricants) considered in this study obeys the rheological model of Bingham. Incorporating the exponential Papanastasiou regularization approach of this model, the governing equations of the physical problem are discretized, using the finite volume method and the SIMPLER algorithm for the pressure–velocity coupling. For a wide range of pertinent control parameters, namely the Reynolds number and the nanoparticles volume fraction as well as the inclination angle of the magnetic field, at a fixed Hartmann number Ha = 100, the results show that, with/without magnetic field, the average Nusselt number increases and the pressure drop decreases with the Reynolds number. The presence of the magnetic field meaningfully increases the heat exchange and increases dramatically the pressure drop, compared to the case without a magnetic field, except for an inclination angle ω = 135°, where the heat exchange rate is reduced. However, nanoparticles improve heat exchange only beyond a yield value of the nanoparticles volume fraction and then become disadvantageous. In addition, the extent of the rigid zone is amplified with the nanoparticles volume fraction and the magnetic field. Finally, the optimal angle offering the best performance is ω = 0°. In addition, the introduction of nanoparticles and the increase in the inertial force increase the gap between the two configurations (2D and 3D). On the other hand, Lorentz’s force weakens the effect of the third direction.

Experimental study for laminar forced convection heat transfer enhancement from horizontal tube heated with constant heat flux, by using different types of porous media

Forced convective heat transfer for water flowing through a circular pipe oriented horizontally has been investigated experimentally. the pipe was heated at constant heat flux and also packed with two different types of particles (steel and mixture of steel & plastic) as a porous media.The flow features are an internal, laminar, incompressible and steady flow for a wide range of Reynolds numbers (500,1000 and 1500) with variable heat flux (200, 400 and 600 W) for each case and three times for each number.The experimental results comprehended temperature recording on different positions of test sections at steady state depending on the effect of the porous media type and Reynolds number employed (which indicate to the mass flux) in addition to the value of heat flux. The results of the study are represented in terms of temperature distribution to show temperature behaviors in the pipe, besides other diagrams uptake relation of the local and average Nusselt number with data aforementioned above. For each porous type, the results show an increase in local and average Nusselt number with increasing of the Reynold number for steel and mixture porous media respectively. It has obverse from this study that in a porous steel media the heat transfer will occur mainly by conduction, while in the other types of porous media that the heat transfer will occur mainly by forced convection.

Effects of Frequency and Jet to Surface Spacing on Synthetic Jet Impingement Heat Transfer

Synthetic jet is a new technique for electronic chip cooling, which combines stagnant air to form a jet resulting from periodic diaphragm oscillations in a cavity. In this work, the heat transfer characteristics of a synthetic jet are investigated experimentally and numerically. A Piston-cylinder arrangement powers the synthetic jet through a circular orifice for the impingement of jet on the heated surface. Air is considered as the cooling medium. The major parameters identified to describe the impinging jet heat transfer are Reynolds number, frequency, ratio of jet spacing to diameter(Z/D) and nozzle geometry. Numerical studies have been carried out using the finite volume based commercial software ANSYS Fluent. The turbulent model used is k-ω model. The dimensionless distance between the nozzle and plate surface is in the range 2 to 16. Numerical results are in fair agreement with experimental results. As the frequency increases the average Nusselt number increases. High frequency synthetic jets were found to remove more heat than low frequency jets for small Z/D ratio, while low frequency jets are more effective at larger Z/D ratio. Nusselt number is maximum at the stagnation point and there occurs a secondary peak at lower Z/D ratios. Synthetic jet with rectangular orifice is more effective as compared to circular and square geometries.

Mixed convection heat transfer of AL2O3 nanofluid in a horizontal channel subjected with two heat sources

Mixed convection flow is investigated numerically for nanofluid flow and heat transfer in a horizontal channel considering two localized heat sources compared with pure fluid. The channel’s walls are insulated and the heat sources are at the center of the channel. Al2O3 nanoparticles are employed to modify the thermal conductivity of the base fluid. The effect of different parameters including Richardson number, Reynolds number, thermal conductivity, sources separation distance and the length-to-height ratio of heat sources is investigated. The results indicate that by enhancing the Richardson number from 1 to 10, the heat transfer from the source surfaces slightly increases; however, no significant effect is observed on thermal behavior. Increasing Reynolds number modifies heat transfer from sources and has a large effect on the streamlines and isotherms. In Richardson number of 5, for Reynolds number of 5, 50, 100, 150, the Nusselt number is 1.01, 4.50, 14.11 and 22.13, respectively. Furthermore, for a higher sources thermal conductivity, heat transfer increases due to the lower thermal resistance. The increase in average Nusselt number with changing the dimensionless thermal conductivity in the range of $$1 \le \bar{k} \le 100$$ is 314%. By examining the length-to-height ratio of heat sources, the results show that heat transfer decreases initially and then increases for higher values of length-to-height ratios. Furthermore, the heat sources separation distance shows a pronounce influence on heat transfer and thermal distribution. Besides, the results show that the effect of nanofluid concentration on average Nusselt number is more significant at low Reynolds number. The increase of average Nusselt number for Reynolds numbers of 5, 80 and 150 is 25%, 15% and 6.5%, respectively.

Numerical simulation of hydrothermal behavior in a concentric curved annular tube

AbstractThis study performs a numerical investigation of the steady‐state fully developed laminar flow and forced convection heat transfer characteristics in a concentric curved annular tube with two different curvature angles, a 90°‐bend annular tube and a U‐bend annular tube. A wide range of aspect ratios (r* = 0.1, 0.25, 0.5, and 0.75) and three curvature ratios (δc = 0.1, 0.2, and 0.5) were adopted in this study. The governing equations consisting of continuity, momentum, and energy equations are solved by considering the outer wall to be insulated (adiabatic), and a constant temperature is applied at the inner wall by using the finite‐volume method (FVM) to investigate the hydrothermal performance for these two different bend angles.Features of axial velocity contours, temperature patterns, and secondary flow streamlines at different cross‐sectional locations along the angular coordinate of curved annulus are observed with a Dean number range of (De = 32‐632). Additionally, the circumferential friction factor and averaged Nusselt number are obtained along the concentric curved annulus flow direction. The numerical results indicate that the normalized average Nusselt number and Performance Evaluation Criteria (PEC) increase with increasing De and curvature ratio for both curvature angles of concentric curved annular tube. Moreover, the normalized average Nusselt number, normalized friction factor‐Reynolds number product, and PEC increase with decreasing the aspect ratio because the annular gap between the surfaces of the inner and outer tubes (the boundaries of annulus) increases with decreasing aspect ratio. The hydrothermal performance of the concentric curved annular tube is higher than that of the straight annular tube attributed to the formation of secondary flows (Dean's vortices) in a cross‐sectional direction and the impact of the inner tube wall boundary. The value of PEC for both curvature angles of the curved annular tube at aspect ratio = 0.1 and De = 632 is approximately two‐fold of the straight annular tube under the same conditions while at aspect ratio = 0.75, it increases by nearly 80%.

Direct Numerical Simulation of Laminar Natural Convection in a Square Cavity at Different Inclination Angle

The effect of angle of rotation on laminar natural convection inside the square cavity have been observed in this research. It was assumed that left and right walls heated isothermally, whereas other two walls act as adiabatic. This problem was solved by assuming 2-D and by Direct Numerical Simulation (DNS) method using ANSYS Fluent 16.0. A series of DNS simulation were carried out for different inclination angle (𝜃 = 0°~90°) of the cavity at Ra = 103 & 104. It was observed that at average Nusselt number increase up to some value of angle of inclination after that it decrease though this variation is not significant.

Effect of Horizontal Spacing on Natural Convection to Power-Law Fluids from Two Horizontally Aligned Cylinders

This paper expounds the effect of horizontal spacing between two horizontally aligned circular cylinders on laminar natural convection to non-Newtonian power-law fluids. Numerical computations have been carried out for the following range of conditions: Grashof number (10 to 105), Prandtl number (0.71 to 100), horizontal spacing (0 to 20 times the cylinder diameter), and power-law index (0.4 to 1.6). The flow, pressure, and thermal fields are pictorially visualized in terms of streamlines, pressure contours, and temperature contours, respectively. The average Nusselt number shows a positive reliance on both Grashof and Prandtl numbers, whereas an adverse dependence is observed on power-law index. Irrespective of all other parameters, shear-thinning fluid behavior is seen to promote the convection, whereas shear-thickening behavior impedes it with reference to the Newtonian fluid. With decrease in the horizontal spacing, the average Nusselt number increases and attains a maximum value corresponding to the optimal spacing, however, it diminishes greatly with further reduction in spacing. Furthermore, the average Nusselt number is in excess of 21-89% at the optimal spacing compared to no-spacing. Finally, this paper is concluded with producing a new correlation for the average Nusselt number.

MHD natural convection and entropy generation in a grooved enclosure filled with nanofluid using two-component non-homogeneous model

In this paper, a computational study of natural convection in a grooved enclosure filled with water-based nanofluid in the presence of external magnetic field is numerically investigated. Two-component non-homogeneous model is introduced to develop the governing partial differential equations. Galerkin finite element method is used to solve the governing equations. The computation is carried out for a wide range of governing parameters such as Rayleigh number (103 ≤ Ra ≤ 106), magnetic field parameter (10 ≤ Ha ≤ 100) and volume fraction of nanoparticles (0% ≤ ϕ ≤ 5%) with fixed values of remaining parameters. A detailed parametric analysis is performed to show the effects of physical parameters on the fluid flow and temperature distributions within the enclosure via streamlines, isotherms, isoconcentrations, mid-sectional velocities, average Nusselt number and temperature, respectively. In addition, the entropy generation and Bejan number are also computed and discussed elaborately. The results of the current study are compared to those of previous numerical and experimental studies and found to be in rational agreements. The results ascertain that the average Nusselt number and entropy generation increase with rising Rayleigh number and nanoparticle volume fraction, whereas they decrease with increasing magnetic field strength. Moreover, it is found that the appropriate combination of governing parameters can maximize the heat transfer rate and minimize the entropy generation as well.

Numerical Investigation on Heat Transfer and Flow Characteristics of a Confined Circular Cylinder With Slit

Abstract Heat transfer and flow characteristics of channel-bounded circular cylinder with a slit vent parallel to the flow direction are numerically investigated using openfoam. The interesting feature of this configuration is the formation of the separation bubble behind the cylinder, which significantly alters the near wake characteristics. In this study, the emphasis is given to understand the effect of the slit on forced convection from the cylinder. Simulations were performed by varying the slit width from 0 to 0.25 (in steps of 0.05) for the range of Reynolds number (Re) 60–240. Re is defined based on the diameter of the cylinder (d) and centerline velocity (Uc) at the inlet of the channel. The influence of s/d and Re on the separation bubble, aerodynamic forces, and heat transfer characteristics are studied in detail. Results demonstrate that the slit can manipulate the flow to mitigate adverse effects of vortex shedding and thus can be used as a passive flow control technique. It was observed that the inclusion of the slit in the cylinder delays the onset of vortex shedding, and it also reduces the fluctuations in aerodynamic forces up to 99%. Compared with the solid cylinder, around 38% increase in vortex shedding frequency, a 16% reduction in drag, and a 10% increase in average Nusselt number is observed when the slit width is 0.25d. It was found that the introduction of slit vent in the cylinder not only enhances the heat transfer along with the reduction in expenditure of pressure loss across the cylinder but also suppresses the fluctuations in aerodynamic forces, which causes vortex-induced vibrations and thus improves structural stability and integrity.

An investigation on the influence of the shape of the vortex generator on fluid flow and turbulent heat transfer of hybrid nanofluid in a channel

The purpose of this study is to numerically investigate flow field and turbulent heat transfer of hybrid nanofluid, water–DWCNT–TiO2 in a two-dimensional rectangular channel with triangular and semicircular vortex generators with three different heights of 1, 2 and 3 mm. For numerically modeling this study, SIMPLEC algorithm was used. Therefore, initially, the geometry of channel and the grid points were generated, and then for solving the mathematical equations via finite volume method, ANSYS Fluent was used. The results indicate that with an increase in Reynolds number and volume fraction (φ) of nanoparticles, the average Nusselt number increases. Also, with an increase in the φ, the pressure loss in the channel increases. About the geometrical shape of the vortex generators, results indicate that with using the semicircular vortex generator, average Nusselt number is higher compared to that of triangular vortex generator. Also, by investigating the performance evaluation criteria of thermal–hydraulic, which is a criterion for comparing the positive effect of the Nusselt number increase with the negative effect of pressure drop, results indicate that this criterion is higher for the semicircular vortex generator.

Second law analysis of magneto-natural convection in a nanofluid filled wavy-hexagonal porous enclosure

Purpose Natural convection heat transfer analysis can be completed using entropy generation analysis. This study aims to accomplish both the natural convection heat transfer and entropy generation analyses for a hexagonal cavity loaded with Cu-H2O nanoliquid subjected to an oriented magnetic field. Design/methodology/approach Control volume-based finite element method is applied to solve the non-dimensional forms of governing equations and then, the entropy generation number is computed. Findings The results portray that both the average Nusselt and entropy generation numbers boost with increasing aspect ratio for each value of the undulation number, while both of them decrease with increasing the undulation number for each amplitude parameter. There is a maximum value for the entropy generation number at a specified value of Hartmann number. Also, there is a minimum value for the entropy generation number at a specified value of angle of the magnetic field. When the volume fraction of nanoparticles grows, the average Nusselt number increases and the entropy generation number declines. The entropy generation number attains to a maximum value at Ha = 14 for each value of aspect ratio. The average Nusselt number ascends 2.9 per cent and entropy generation number decreases 1.3 per cent for Ha = 0 when ϕ increases from 0 to 4 per cent. Originality/value A hexagonal enclosure (complex geometry), which has many industrial applications, is chosen in this study. Not only the characteristics of heat transfer are investigated but also entropy generation analysis is performed in this study. The ecological coefficient of performance for enclosures is calculated, too.

Enhancement of Heat Transfer in Perforated Circular Finned-Tube Heat Exchangers: A Numerical Investigation

The effects of employing perforations of circular shape in circular finned-tube heat exchangers (CFTHEs) are numerically investigated in the present study using Computational Fluid Dynamics (CFD) software. Simulations performed on the validated CFD model shows considerable increase in the Average Nusselt Number for perforated circular finned-tube heat exchangers (PCFTHEs) as compared to their solid counterpart, with only a slight increase in Euler Number for 10,000 ≤ Re ≤ 50,000. Diameter of perforations (dp ) is kept equal to 6mm and optimum range of number of perforations per fin (np ) by analysis is found to be 16 to 20. For this range, the performance of PCFTHEs improves with the increase in number of perforations per fin. The maximum increase in Average Nusselt Number is 24% for dp = 6mm and np = 20 at Re = 10,000. The minimum increase in Average Nusselt Number is 3% for dp = 6mm and np = 14 at Re = 40,000. This increase in Average Nusselt Number on introducing perforations is due to (i) flow of localized air jets through the perforations, and (ii) reduction in recirculation region caused by the separation of flow. This improvement in the performance of CFTHEs on introducing perforations is achieved with the maximum and minimum reduction in weight of 41% and 29% respectively.

Numerical evaluation of the thermal performance of a solar air heater equipped with two different types of baffles

AbstractIn the present study, the effect of utilizing two different types of baffles in the channel of the solar air heater is investigated numerically. The studied baffles include angled rectangular baffles and angled V‐shaped baffles, which are mounted on the bottom and top walls of the duct, respectively. Both considered baffles were evaluated separately which the studied parameter in each section was the angular position of baffles. Finally, the best‐obtained results of both sections were compared to each other. The results indicated that in the rectangular model by comparison between 90° model and no baffle, it was found that the pressure drop and average Nusselt number increase 316.67% and 148.15%, respectively at Reynolds number (Re) = 2000. Also, in V‐shaped angled baffles, the thermal efficiency of β = 90°, 60°, 45°, and 30° are 27%, 18%, 13% higher than no baffle channel at Re = 2000, respectively. Furthermore, at low Re (about Re below 300), utilizing baffles into the channel had no effect on the thermal efficiency of the system compared to the no baffle channel. However, at high Re, it was found that the highest thermal efficiency occurred in the model of rectangular baffles with an angle of 90°.

Numerical Study on Hydrothermal Performance Factor Using Jet impingement and Nanofluid

In this study, thermal-hydraulic performance of a confined slot jet impingement with Al2O3-water nanofluid has been numerically investigated over Reynolds number ranges of 100-1000. Two triangular ribs are mounted at a heated target wall; one rib located on the right side of the stagnation point and another one located on left side of the stagnation point. The governing momentum, continuity and energy equations in the body-fitted coordinates terms are solved using the finite volume method and determined iteratively based on SIMPLE algorithm. In this study, effects of Reynolds number, rib height and rib location on the thermal and flow characteristics have been displayed and discussed. Numerical results show an increase in the average Nusselt number and pressure drop when Reynolds number and rib height increases. In addition, the pressure drop and average Nusselt number increases with decrease the space between the stagnation point and rib. The maximum enhancement of the average Nusselt number is up to 39 % at Reynolds number of 1000, the rib height of 0.3, rib location of 2 and nanoparticles volume fraction of 4%. The best thermal-hydraulic performance of the impinging jet can be obtained when the rib height of 0.2 and rib location of 2 from the stagnation point with 4% nanoparticles volume fraction.

Effect of γ-Al2O3/Water Nanofluid on Natural Convection Heat Transfer of Corrugated ┐ Shaped Cavity: Study the Different Aspect Ratio of Grooves

In this paper, the effect of γ-Al2O3/water nanofluid on the flow pattern and natural convection heat transfer of corrugated ⅂ shaped cavity is investigated numerically by the Lattice Boltzmann Method (LBM). The effects of nanoparticles solid volume fraction (ϕ=0-0.006), Rayleigh number (Ra=103-106) and the aspect ratio of grooves cavity (h/H=0.05-0.15) on the streamlines, isotherms and averaged Nusselt number have been examined. In addition, a comparison between γ-Al2O3/water nanofluid and MWCNT-Fe3O4/Water Hybrid Nanofluid on the average Nusselt number are studied. The results showed that the heat transfer rate of γ-Al2O3/water nanofluid is higher than water. For all Rayleigh numbers and solid volume fraction of nanoparticles, increasing the height of grooves leads to an increment in average Nusselt number. Moreover, when the Rayleigh number reaches to 106, the average Nusselt number increases, which the domain mechanism of heat transfer, in this case, becomes convection. As to be expected, the influence of MWCNT-Fe3O4/Water Hybrid Nanofluid on heat transfer rate is higher than the γ-Al2O3/water nanofluid.

Experimental Study of Mixed Convection from Horizontal ‎Isothermal Elliptic Cylinders at Different Aspect Ratios

ABSTRACTMixed convective heat transfer from horizontal isothermal elliptic cylinder is experimentally studied. Three elliptic test cylinders with same perimeter and length are studied giving axis ratio (AR) equal 1, 0.709 and 0.496. The corresponding Gr for the three test sections is 9.8 × 105, 1.5 × 106, and 2.1 × 106, and Re varies from 111 to 1306. Consequently, the corresponding Ri is in range of 1 to 102. The angle of attack (ψ) is changed from 0° (assisting flow) to 180° (opposing flow) with an interval of 30°. New empirical correlation is obtained for the Nuavg as a function of the AR, Ri, and ψ. The experimental results are presented in the form of the average Nusselt number around the elliptic cylinder. It has been concluded that as the axis ratio decreases the averageNusselt number increases, in addition, increasing the angle of attack from 0° to 180° decreases the averageNusselt number considerably. New empirical correlations are obtained for the average Nusselt number as a function of the Richardson number and the attack angle.

Natural convection in inclined channel for air cooling of photovoltaic panels

Reducing the operating temperature of a photovoltaic (PV) module is an effective way to improve efficiency and prevent damage from overheating. The present paper focuses on the study of the effect of inclination on air natural convection in an asymmetrically heated channel (at uniform heat flux), in laminar regime. This configureuration models the passive and natural air-cooling of PV panels by inclined chimneys. The computational procedure solves the unsteady two-dimensional Navier-Stokes and energy equations by a finite volume approach while the projection method decouples the pressure from the velocity. The heat transfer and fluid flow are analyzed for a wide range of modified Rayleigh numbers varying from 102 to 105 and for inclination angles between 15o and 90o with respect to horizontal position. The results show that the mass flow rate and the average Nusselt number increase with the angle of inclination as well as with the modified Rayleigh number. However, a significant reduction in heat transfer rate and induced flow rate is observed for the low angles of inclination. To enhance the cooling of the PV panel, extensions are added at the inlet and outlet of the channel. The simulations show that only the downstream extensions of the channel are effective in improving the induced mass flow rate and therefore the convective heat transfer.

Hydrodynamic and thermal study of a trapezoidal cylinder placed in shear-thinning and shear-thickening non-Newtonian liquid flows

Hydrodynamic and thermal features of two-dimensional, incompressible shear-thinning and shear-thickening non-Newtonian power-law liquids under forced convection across a trapezoidal cylinder are the focus of this study, carried out at Reynolds number Re = 1–40, power-law index n = 0.4–1.8 and Prandtl number Pr = 50 using ANSYS Fluent. In this steady system, the drag coefficient is found to decrease, whereas the wake size and the average Nusselt number increase with the increase in Re. However, with the increase in n value, the average Nusselt number decreases. Similar to a square cylinder, compared to Newtonian liquids, shear-thinning liquids increases heat transfer and shear-thickening reduces it. The maximum increase in heat transfer for shear-thinning liquids compared to Newtonian liquids for a trapezoidal cylinder is approximately 25%, while the average heat transfer is somewhat lower for shear-thickening liquids than for Newtonian. The average Nusselt number is smaller for the trapezoidal cylinder than for a square cylinder in the parameter domain investigated; the largest difference is around 25%. A simple relationship for the average Nusselt number as a function of Re and n has been determined.

Effect of non-uniform asymmetric heating on the thermal and entropy generation characteristics for flow of Al2O3-water nanofluid in a micro-channel

Purpose The purpose of this study is to numerically analyze the thermal and entropy generation characteristics on two-dimensional, incompressible, laminar single-phase flow of Al2O3-water nanofluid in a micro-channel subjected to asymmetric sinusoidal wall heating with varying amplitude, length of fluctuation period and phase difference of applied heat flux for Reynolds number in the range of 25-1000. Design/methodology/approach The numerical computation is based on the Finite Element Method and the Lagrange finite element technique is used for approximating the flow variables within the computational domain. Findings The average Nusselt number increases with increasing Reynolds number (Re) for all the volume fractions of nanofluid. However, the total entropy generation decreases up to a critical value of Re and increases thereafter. Increase in volume fraction shifts the critical Re towards the lower Re regime. The average Nusselt number and total entropy generation increase with amplitude and length of fluctuation period of heat flux. The optimal choice of volume fraction for lesser entropy generation and higher heat transfer is found to be 3 per cent independent of the value of amplitude, length of fluctuation period and phase difference of the heat flux. Originality/value To the best of authors’ knowledge, the interplay of various parameters concerning non-uniform heating in achieving the maximum heat transfer with minimum irreversibility has not been investigated. Focusing on this agenda, the results of this study would benefit the industrial sector in achieving the maximum heat transfer at the cost of minimum irreversibilities with an optimal choice of inlet Reynolds number, volume fraction of nanofluid, amplitude, length of the period of fluctuation of heat flux and phase difference of applied heat flux.