Forced Convection Heat Transfer Research Articles

Forced convection heat transfer from a plate stack embedded in a homogeneous porous medium

The current paper examines some novel and interesting aspects of the mathematical modelling of fluid flow and forced convection heat transfer from a plate stack embedded in a homogeneous porous media. Time-dependent forced convection heat transfer from some cylinders embedded in groundwater are explored numerically using finite difference methods. An algorithm was developed about rectangular heated solid objects with the same size placed in an in-line arrangement in homogeneous porous media. Central and one-sided finite difference formulae are used to discretize the domain. Applying the mathematical model, continuity, momentum, and energy equations are solved by the finite difference methods. Generally, analytical solutions are not possible for such problems, so most of the work is done numerically. The numerical results for the two-dimensional velocity potential and stream function have been calculated and the resulting fluid and temperature contours are represented graphically for various values of the parameters involved (e.g. length of the entrance, the fluid flow rates, coefficient of thermal diffusion and advection in the observed long-time plume behaviour, effect of time and temperature on heat transfer, etc.). It is observed that fluid and heat fluxes and fluid velocity depend upon the size, shape, burial depth, position of heated objects, and positions of the entrance and exit of the homogeneous porous media. Moreover, the hydraulic conductivity of the porous medium affects the pressure drops, fluid velocity as well as the heat transfer rates.

Thermodynamic analysis of entropy generation in a horizontal pipe filled with high porosity metal foams

In the field of thermal management of electronic equipment , examining entropy generation properties is extremely useful. The entropy production experiments have been expanded to porous media using high porosity metal foams. The entropy production/generation for forced convection heat transfer in a tube is quantified via a numerical research. In the field of air stream direction, the horizontal pipe is entirely filled with nickel metal foam of 0.6 m length. For the isotropic porous metal foam zone, the Darcy-extended Forchheimer (DEF) flow is used to capture the dynamics of flow and local thermal non-equilibrium (LTNE) model is used for analyzing the heat transport phenomenon, while the k-ɛ turbulent model is used for the non-foam porous region of the tube. The effect of fully filled nickel metallic foam with different pore densities of 10, 20, and 30 metal foam with a porosity of 0.85 is being investigated. The computational solutions presented here are supported by experimental results published in the literature. The outlet exergy of the system rises with higher flow rates and falls with higher metal foam pore densities. The results of entropy generation due to thermal and fluid friction and Bejan number conceptions are also shown and discussed.

Experimental Investigation of Near- and Supercritical Heat Transfer to R125 Flowing in a Horizontal Tube

Knowledge about supercritical heat transfer to refrigerants with horizontal flow is scarce and experimental data is mostly lacking. This makes an accurate sizing of heat exchangers impossible. In addition, the majority of the tested geometries in literature are limited to an inner diameter of only 16 mm. In order to close the gap and increase the knowledge about supercritical heat transfer, a novel experimental setup was used to investigate supercritical heat transfer phenomena on larger tube diameters. The test section consists of a horizontal counter current tube-in-tube heat exchanger. R125 flows in the inner tube having an inner diameter of 24.77 mm. The influence of mass flux (226 - 585 kg/m2s), heat flux (7.7 - 21.9 kW/m2) and supercritical pressure (3.7 - 4.1 MPa, corresponding to 1.03 - 1.12 times the critical pressure) on local forced convective heat transfer was investigated. No visible influence of pressure on the convective heat transfer coefficient is noticed, indicating that buoyancy is present and influential in the performed measurements. The applied heat flux does have an effect, with a decrease in the heat transfer coefficient for an increase in heat flux. This effect is more pronounced at higher mass fluxes. At high mass flux, increasing the heat flux with 42% results in a drop in heat transfer coefficient of 46%, while this is only 40% and 26% at medium and low mass flux, respectively. However, there appears to be a limit to this detrimental effect at higher mass fluxes. Finally, heat transfer increases for an increase in mass flux. Increasing the mass flux with 76% results on average in a rise in heat transfer coefficient of 88%, for measurements at medium heat flux. At high heat fluxes, an increase of 71% is observed for a rise in mass flux of 59%. Nine heat transfer correlations are evaluated. The majority underestimates the heat transfer significantly, however, two correlations operate adequately and are proposed as a basis for future correlation development. The unique dataset and insights presented in this work enable a better understanding of the heat transfer in supercritical vapor generators. Future work includes incorporating top and bottom wall temperature measurements, adjusting control and application of the heat flux and investigating refrigerants with a low Global Warming Potential.

Influence of position on the natural and forced convective heat transfer of a single heating sphere in a packed bed

Natural and forced convection experiments on a single heating sphere in a packed bed were performed by varying the axial and radial positions of the heating sphere. Based on the analogy between heat and mass transfer, mass transfer experiments were conducted using a copper electroplating system. The sphere diameter was varied from 0.004 to 0.010 m, which correspond to the Rad of 5.43 × 106–8.48 × 107. The Sc was 2,014. In the forced convection experiments, the range of superficial velocity was 0.01 to 0.58 m/s, which correspond the Red of 43–5,076. For natural convective flow, the influence of sphere position on the heat transfer of single heating sphere in the packed bed was not observed. However, for forced convective flow, the local heat transfer inside the bed was affected by the variation of the sphere position. The heat transfer increased at the downstream layer of bed due to the intensified turbulence level by the porous structure. The heat transfer near wall region was also enhanced due to the high local porosity. Based on the experimental results, we developed the correlation of local heat transfer for forced convection by adding the multiplier to the existing correlation.

Data-driven multifidelity topology design using a deep generative model: Application to forced convection heat transfer problems

Topology optimization is a powerful methodology for generating novel designs with a high degree of design freedom. In exchange for this attractive feature, topology optimization cannot generally avoid multimodality, which often impedes finding a satisfactory solution when dealing with strongly nonlinear optimization problems. In this study, we focus on constructing a framework that aims to indirectly solve such complex topology optimization problems. The framework is based on multifidelity topology design (MFTD), the basic concept of which is to divide solving an original topology optimization problem into two kinds of procedures, i.e., low-fidelity optimization and high-fidelity evaluation. We build the framework as a data-driven approach, where the design candidates given by solving the low-fidelity optimization problem are iteratively updated based on the idea of the evolutionary algorithm (EA). As a key procedure to realize a crossover-like operation in the high-dimensional design space, a variational autoencoder—one of the representative deep generative models—is utilized for generating a new dataset composed of various material distributions. Besides, we propose a mutation-like operation for generating novel material distributions based on reference ones in the dataset. By integrating these operations with an elitism-based selection procedure, we propose data-driven MFTD that enables gradient-free optimization even if tackling a complex optimization problem with a high degree of design freedom. We apply the proposed framework to forced convection heat transfer problems, where the low-fidelity optimization problem is formulated using a Darcy flow model, whereas the high-fidelity evaluation is conducted using a Navier–Stokes model. We first demonstrate that the obtained results from the proposed framework can achieve almost identical performance compared with that of the directly solved results in a well-known 2D laminar heat transfer problem. We then show that the proposed framework can find solutions in minimax problems of topology optimization pertaining to 3D laminar and turbulent heat transfer.

Viscous dissipation in the heat transfer between a rotating cylinder and viscous media under forced convection

The effects of viscous energy dissipation on the forced convection heat transfer between an unconfined rotating isothermal circular cylinder and surrounding viscous fluids are numerically investigated. The heat transfer characteristics are investigated for the range of conditions of the Reynolds number Re = 1-40, Prandtl number Pr = 1-100 (the Peclet number ranges between 1 and 4000), dimensionless rotational velocities α = 0-3, and Brinkman number Br = 0-1. For the steady flow regime, the isotherm patterns are presented for the range of values of Reynolds number, Brinkman number, Prandtl number, and rotational velocity. For low Peclet numbers (Re×Pr), the heat generated by the viscous dissipation is not efficiently removed which, promotes the appearance of hot spot zones. The variation of the local and average Nusselt numbers on the cylinder surface shows the effects of Brinkman number, Prandtl number, and rotational velocity on heat transfer between a rotating isothermal cylinder and a viscous flow for the range of conditions studied.

Numerical study of laminar forced convection heat transfer in a rough mini-channel fabricated by Additive Manufacturing

This study investigates laminar convective heat transfer of water flowing in a mini-channel with a rough surface fabricated by Laser-based Powder Bed Fusion (L-PBF) technology. A Gaussian model was used for generating random roughness, and then the three-dimensional numerical simulation was performed in ANSYS-Fluent 19.1. The numerical results indicated a more than double increase in the Nusselt number of rough channels than that of smooth ones with a marginal pressure drop penalty compared to smooth channels, showing the potential benefits of using rough channels fabricated by L-PBF for heat transfer applications.

Numerical investigation of forced convective heat transfer of nanofluids within an enclosure

Heat transfer applications normally observed day-to-day are mainly focused on forced convection such as the transfer of hot fluid being pumped through pipes, shell and tube heat exchanger and power plants. The heat transfer characteristics of nanofluids present within a cubical enclosure subjected to forced convection is analysed here. Assisting and opposing forced convection flows are being compared. The inlet through which a nanofluid enters the cubical enclosure at a uniform velocity is positioned at the lower portion of the left wall for the assisting case and situated at the upper portion of the left wall for the opposing case. An in-house solver based on finite difference method is developed using simplified marker and cell algorithm (SMAC) through which the simulation is performed. The nanofluid chosen here is a water-based one with various nanoparticles such as aluminium (Al), silver (Ag), aluminium oxide (Al2O3) and singled wall carbon nanotubes (SWCNT) which are investigated for a Reynolds number range of 103 to 105. Other parametric studies like the volume concentration is also being varied from 0% to 3%. The results of this paper tend to show that heat transfer characteristics increase with an increase in both Reynolds number and volume concentration. Forced convection occurring through assisting flow case is showing better heat transfer than in the opposing flow case.

Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators

The main goal of the research presented in this paper was the experimental and numerical analysis of heat enhancement and aerodynamic phenomena during air flow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies the heat transfer and at the same time increases not only the flow resistance but also the energy costs. Therefore, designing modern heat exchangers with optimal thermal and flow parameters requires the knowledge of the theory of heat exchangers as well as measurement methods and numerical calculations. Bearing in mind the above, the liquid crystal techniques (LCT), particle image velocimetry (PIV) and digital image processing (DIP) for temperature, velocity, friction factor and heat transfer coefficient measurements are presented herein. These three optical tools (using desktop computers) create an extremely powerful and advanced measuring technique that has not been available anywhere before. Brief histories of these measurement methods and techniques are discussed and some examples are presented. In order to assess and select the value of the measurement technique, local and average distributions of Nusselt numbers (in the measurement section) obtained by the transit analysis method on the inter-rib regions of a plate coated by thermochromics liquid crystal and heated by air as an alternative to the steady-state analysis. In the parallel, numerical calculation was performed with the use of the ANSYS Fluent software code and supported by laser anemometry-computed turbulence intensity of air flow. Comparison of the Nusselt number distributions was determined by three methods, i.e., steady state, the transient method and CFD simulation. Up to three-fold enhancement of the local heat transfer capability was observed. Failure to take into account the surface of the ribs in heat transfer causes differences in the obtained results of the Nusselt number depending on the method used. Apart from the heat transfer data, the pressure drop in the form of friction factors is also presented. On the basis of the conducted research, it can be stated that both qualitative and quantitative coherence was obtained between the experimental and computational studies.

Performance Evaluation of Shell and Tube Heat Exchanger by Using Fe3O4/water Nanofluidid

This paper studies the forced convection heat transfer and flow characteristics of nanofluids composed of water and different volume concentrations of Fe3O4/water nanofluids (0.35%, 0.2%) under laminar flow conditions that move in counter current in a vertical shell-and-tube heat exchanger. Fe3O4 nanoparticles having a diameter of about 30 nm were used in this work. Various of Reynolds number were used during practical experiments on the device is (200,600,1000,1400). The results show that for the same mass flow and inlet temperature, the convective heat transfer coefficient of the nanofluid is slightly larger than that of the base fluid where the improvement ratio is up to 14%, 22% for 0.2%, 0.35%, respectively. Where it was concluded through the results that the total coefficient of heat transfer of the nanofluid has increased compared to the basic fluid, the maximum improvement at (0.2%, 0.35%) was about 34% and 61%, respectively. When the concentration of nanofluids increases sharply, the Nusselt number also increases sharply compared with the base fluid up to 10%, 19%. As the results showed that the friction factor increases when the concentration of nanofluid increase because the density and viscosity is higher than of base fluid, while decrease when the Reynolds number increase, where the ratios reached 25%, 47%. It was found that the effectiveness of nanofluids is higher than that of base fluids is up to 56%, 62%.

Thermo-fluidic analysis of a single piezofan in longitudinal channel

Most past surveys and conclusions have clearly indicated that more than 55% of electronic device's failures are related to the inability to control high heat generated entirely. The conventional cooling methods typically consist of air-cooling processes, which involve various types of heat sinks in free and forced convection, becomes inadequate to meet the cooling requirements with high performance, compact size, and increased heat generation advanced electronic devices.The main aims of this investigation are (i) to analyze the airflow around a horizontally oriented piezofan, which is oscillating transversally to longitudinal channel airflow, and (ii) to show its applicability to achieve successful thermal management on a flat heated surface at an electronic component. The coupled-analysis was performed on a 2D-laminar flow model by combining the cantilever motion analysis with fluid flow and heat transfer using COMSOL Multiphysics software. The model based on the finite element method (FEM) is determined using an Arbitrarily Lagrange-Euler scheme (ALE) in Fluid-Structure-Interaction (FSI) analysis. The cooling performance of piezofan is computed by evaluating the average forced convective heat transfer coefficient at the heated section of the channel surface with an inlet flow velocity of uin = 0.1 m/s, i.e., Rem = 1040. The simulation results have shown the high performance of these fans compared to without piezofan flow conditions. The best performance was obtained at which the moving tip of the fan at the middle of the heated surface (∆xp = −20 mm) with a distance from the heated surface of G = 7 mm. Compared with the laminar flow conditions without piezofan, the convection heat transfer coefficient is increased by 231%.

Numerical Verifications on Heat Transfer to Supercritical Water Flowing Upward in a 4-m Long Bare Vertical Tube

Abstract Thermal efficiency and safety of generation-IV nuclear-power-reactor concept supercritical water-cooled reactor (SCWR) are largely dependent on the coupled supercritical water (SCW) thermophysical properties and heat transfer performance in the supercritical region. This paper presents the numerical investigation of the heat-transfer characteristics of SCW flow in a 4-m long circular tube (ID = 10 mm) based on computational fluid dynamics. Numerical model for SCW was established in this analysis and forced-convection heat transfer was studied at different operating conditions. The data were collected at pressure of about 24 MPa, inlet temperatures from 320 to 350 °C, mass flux from 1000 to 1500 kg/m2·s, and heat flux up to 1500 kW/m2. Results of numerical simulation predict the experimental data with reasonable accuracy. A dimensional analysis was conducted to derive the general form of an empirical supercritical water heat-transfer correlation. The decrease of turbulent viscosity due to the decrease of density leads to a lower turbulent diffusion and turbulent kinetic energy, which inhibits heat transfer. The increased wall temperature and localized heat transfer deterioration (HTD) would occur as the liquid in the core of the tube is isolated for the low-density fluid adheres to the near-wall region, which is characterized by low thermal capacity.

Enhanced forced convection heat transfer of a heat exchanger tube utilizing serrated-ring turbulators

Experiments were performed to study the thermohydraulic behaviors of heating tubes equipped with serrated-ring bundles as turbulators. Their thermohydraulic characteristics are reported in terms of Nusselt numbers (Nu) and friction factors (f) as well as performance in terms of a thermohydraulic performance index (TPI) at identical pumping power. Influences of serrated-ring diagonal angles (θ = 15°, 30°, 45° and 60°), pitch ratios (PR = 6.0, 8.0 and 12.0) and Re were examined. Various geometries of serrated-ring bundles can affect the laminar sub-layer disruption, creating a reversing flow, reconnecting the separated flow to the surface, and delaying the thermal/velocity boundary layer development. These are the most important mechanisms that lead to enhanced force convection heat transfer in a fluid flow. The heat transfer rate, friction loss and TPI increased with decreasing pitch ratio (PR) and serrated-ring diagonal angle (θ ). Heat transfer rate and friction factor were increased to 2.2 and 8.8 times that of a plain tube, respectively. Over the range investigated, the highest TPI, 1.16, was found using a serrated-ring bundle having θ = 15° and PR = 6.0 at Re = 4000.

Efficacy of turbulent convective heat transfer in a circular tube with water-based nanoemulsion of n–Eicosane–An experimental study

The water-based microemulsion or nanoemulsion of phase change materials, that can be used as the dual functional thermal fluids for energy transport or/and energy storage, have received many attentions due to their practical applications in convective heat transfer improvement and thermal energy storage. This is owing to the advantages of these fluids in providing high effective specific heat resulted from latent heat release/absorption associated with freezing/melting behaviors within the phase change material particles. In general, it is important to evaluate the long-term overall energy efficiency of these fluids, used in thermal systems, under the practical and complex conditions. To address this issue, in the present study, the turbulent forced convective heat transfer of water-based nanoemulsion in a circular tube is experimentally investigated. The n-Eicosane, as a phase change material, with different mass fractions is suspended in the water by an ultrasonic-vibrator-aided emulsion process to prepare the nanoemulsion fluid. The circular tube is under a constant heat flux. The effects of different parameters, such as the Reynolds number, mass fraction of n-Eicosane particles, and heating power, on the dimensionless wall temperature, local convective heat transfer effectiveness, temperature control effectiveness, figure of merit (FOM), and pressure drop are studied. The experimental results reveal that the local convective heat transfer effectiveness decreases as the heating power increases. The use of n–Eicosane particles with smaller value of mass fraction can provide the convective heat transfer effectiveness larger than unity in the entire length of the heating section. The heating power has little effect on the pressure drop ratio. Increasing the heating power leads to a marginal decrease in the pressure drop ratio at larger values of the Reynolds number. The FOM index decreases as the mass fraction of n–Eicosane particles increases. The FOM index is decreased about 10% as the mass fraction of n–Eicosane particles increases in the range of 1% to 5% for the Reynolds number in the range of Re=4548∼4677. This decrease is 10.55% for the Reynolds number in the range of Re=5044∼5195. In addition, the FOM index is reduced with increasing the Reynolds number. The FOM index reduces about 1.3% as the range of Reynolds number increases from 4548∼4677 to 5044∼5195 for ωPCM=5%.

A Comparative Study of Multiple Regression and Machine Learning Techniques for Prediction of Nanofluid Heat Transfer

Abstract The aim of this article is to introduce and discuss prediction power of the multiple regression technique, artificial neural network (ANN), and adaptive neuro-fuzzy interface system (ANFIS) methods for predicting the forced convection heat transfer characteristics of a turbulent nanofluid flow in a pipe. Water and Al2O3 mixture is used as the nanofluid. Utilizing fluent software, numerical computations were performed with volume fraction ranging between 0.3% and 5%, particle diameter ranging between 20 and 140 nm, and Reynolds number ranging between 7000 and 21,000. Based on the computationally obtained results, a correlation is developed for the Nusselt number using the multiple regression method. Also, based on the computational fluid dynamics results, different ANN architectures with different number of neurons in the hidden layers and several training algorithms (Levenberg–Marquardt, Bayesian regularization, scaled conjugate gradient) are tested to find the best ANN architecture. In addition, ANFIS is also used to predict the Nusselt number. In the ANFIS, number of clusters, exponential factor, and membership function (MF) type are optimized. The results obtained from multiple regression correlation, ANN, and ANFIS were compared. According to the obtained results, ANFIS is a powerful tool with a R2 of 0.9987 for predictions.

Enhancing Forced Convection Heat Transfer Annular Tubes by Using Aluminum Mesh Layers. (Dept. M)

Enhancing Forced Convection Heat Transfer Annular Tubes by Using Aluminum Mesh Layers. (Dept. M)

Unsteady numerical simulation and optimization of 499.8 MHz superconducting cavity cooling process at the High Energy Photon Source (HEPS)

Superconducting 499.8 MHz β single cell ellipsoidal cavities of quarter-wave geometry have been chosen for the High Energy Photon Source (HEPS). The cooling process of the superconducting cavity from the room temperature to 4.2 K is an unsteady forced convective heat transfer process. Its heat transfer mechanism analysis and efficient cooling strategy in the cooldown process is insufficient in present studies. In this paper, a three-dimensional coupled heat-flow model of 499.8 MHz superconducting cavity was built. The unsteady temperature distributions of the superconducting cavity in different inlet temperature condition were studied, serving as the training samples for the neural networks. The agent models based on the two sets of Back-Propagation (BP) neural networks (BPNet1 and BPNet2) were designed to obtain a set of quick calculation model. Genetic algorithm (GA) was used to perform the results optimization. The cooling time of the optimized cooling method could be reduced from 480 min to 290 min, with a reduction of about 40% compared the traditional cooling method. The standard deviation σsk of the modified cooling method was 0.56. The maximum temperature difference in each cooling stage approximately approached the allowed temperature difference 20 K, indicating the potential of the cooling method was maximized. The modified cooling method could shorten the total cooling time and greatly improve the efficiency during the cooldown process.

Investigation of forced convective heat transfer with magnetic field effect on water/ethylene glycol-cobalt zinc ferrite nanofluid

In this work, the magnetic field effect on the convective heat transfer (CHT) properties of nanofluids comprising cobalt–zinc ferrite nanoparticles were experimentally studied. The nanofluid was prepared by dispersing the cobalt–zinc ferrite nanoparticles in the water and ethylene glycol mixture (80:20) and subjected to heat transfer studies. The experiment result exhibited that the CHT coefficient increased with the increase in the nanofluid concentration. The maximum CHT coefficient exhibited at a concentration of 0.2 wt%, which was improved by about 23.9%. It was also found that the CHT coefficient at a magnetic field of 750 G was increased by about 2.64% compared to that at 0 G for 0.2 wt% cobalt–zinc ferrite nanofluid concentration. The nanofluid with 0.2 wt% cobalt–zinc ferrite concentration exhibited the maximum CHT coefficient and pressure drop increase rate by 17% when the magnetic field was increased from 0 to 750 G.

Forced convection heat transfer of aviation kerosene enhanced by electric field in a circular channel

• Using EHD technique to enhance avionics system heat dissipation is proposed. • Electrical properties of aviation kerosene in wire-tube EHD structure are studied. • Inlet parameters affecting the EHD heat transfer enhancement is investigated. • Flow, temperature and electric fields are captured by numerical simulation. Coolant heat transfer capacity determines the security of avionics system operation. Electrohydrodynamics (EHD), as an enhanced heat transfer technology, can be applied to the avionics cooling system. In this paper, the forced convection heat transfer characteristics of aviation kerosene enhanced by the EHD technique were investigated by both experimental and numerical simulation methods for the first time. One kind of wire-tube structure heat exchanger was designed and the heat dissipation performance of aviation kerosene was tested experimentally at different inlet parameters and electric potentials. A 3D mathematical model was established based on Maxwell and Navier-Stokes equations and the finite volume method was used for conservative discretization of the governing equations. The experimental and numerical simulation results are in good agreement. In the range from 128 to 900 of Reynolds number, the EHD heat transfer enhancement effect becomes weaken with the increase of mass flow. The charge migration along the electric field is suppressed due to the increasing axial velocity. However, the heat transfer enhancement effect is more obvious with the increasing inlet temperature of aviation kerosene. Due to the low viscosity and high ion mobility of high-temperature aviation kerosene, the charge migrating ability is enhanced and the viscous resistance is easier to overcome to produce the secondary flow. The maximum heat transfer enhancement ratio can reach 1.9 times. This paper expanded the EHD application to aviation fuels as the coolant in avionics systems and provided a deeper understanding on inlet parameters affecting the EHD heat transfer enhancement.

Forced convective flow and heat transfer past a blunt headed cylinder with corner modification

A numerical analysis is performed to elucidate the forced convective fluid flow and heat transfer characteristics past a blunt-headed cylinder. Simulations are carried out employing air (Pr = 0.71) as an operating fluid in a Reynolds numbers range 40≤Re≤200. The curvature ratio is varied from 0 to 0.5. The flow and heat transport features are elucidated in detail for different curvature ratios. Important flow parameters such as boundary layer thickness, vortex strength, wake width, drag, lift, skin friction coefficient, pressure coefficient, Strouhal number, and recirculation length are computed. Also, a primary stability analysis has been carried out using the Landau equation, whereas secondary stability analysis has been done implementing dynamic mode decomposition (DMD) to compute the critical Reynolds number at each curvature ratio. Calculating local and time-averaged values of Nusselt numbers, heat transfer characteristics are studied. An entropy generation analysis is done to investigate the effects of corner modification on the efficacy of thermofluid transport characteristics.