Laboratory modeling of the momentum and heat transfer within wind-wave interaction in a wide range of conditions including extreme (hurricanes and storms)

Equations are derived for mean friction and heat transfer coefficients to solve problems of updating industrial plants for getting oil fractions based on application of approximate method of modeling momentum and heat transfer in heat exchangers with surface intensifiers. The Dyssler and Van-Driest turbulent boundary-layer model is used for the turbulent viscosity function for a flat smooth wall. An equation for the Stanton number is written using Chilton-Colborne hydrodynamic analogy and agreement with the known analogy is shown. Identical local properties of turbulent motion in a boundary layer on a plate and in a near-wall layer of a tube and the conservative properties of the laws of friction and heat transfer to turbulences, which are taken account of parametrically, are used for modeling momentum and heat transfer in channels with surface intensifiers. An equation for mean tangential stress in channels with intensifiers and, further, an equation for the Nusselt number is derived using a dissipative model. The results of calculations and comparison with the known experimental investigations are given for tubes with surface wire inserts, with spiral finning and rectangular projections for transformer oil at Reynolds numbers 200 < Re <2000. Thus, the adequacy of the developed mathematical model is proved in a wide range of operating and design parameters and thermophysical properties of fluids and gases. Further, the hydraulic resistance of the channel is the key experimental information about the object of modeling. Examples of use of mathematical model for designing and commissioning heat exchangers in petroleum fuels fractionating plants at industrial enterprises in the Russian Federation and abroad are given.

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Coupling Between Heat and Momentum Transfer Mechanisms for Drag-Reducing Polymer and Surfactant Solutions

Journal of Heat Transfer ◽

10.1115/1.2826068 ◽

1999 ◽

Vol 121 (4) ◽

pp. 796-802 ◽

Cited By ~ 32

Author(s):

G. Aguilar ◽

K. Gasljevic ◽

E. F. Matthys

Keyword(s):

Heat Transfer ◽

Momentum Transfer ◽

Direct Coupling ◽

Surfactant Solutions ◽

Wide Range ◽

Momentum And Heat Transfer ◽

Local Measurements ◽

Friction Measurements ◽

Heat And Momentum Transfer ◽

Transfer Mechanisms

Drag-reducing solutions exhibit simultaneous friction and heat transfer reductions, yet it has been widely believed that there is no direct coupling between the two. In this work, we have conducted a study to re-examine this issue, using measurements of friction and heat transfer over a wide range of flow conditions from onset to asymptotic, various pipe diameters, and several polymer and surfactant solutions. Contrary to some earlier suggestions, our tests show that no decoupling of the momentum and heat transfer mechanisms was seen at the onset of drag reduction, nor upon departure from the asymptotes, but rather that the friction and heat transfer reductions change simultaneously in those regions. For asymptotic surfactant and polymer solutions, the ratio of heat transfer and drag reductions was seen to be constant over a large range of Reynolds numbers, if modified definitions of the reduction parameters are used. In the nonasymptotic region, however, the ratio of heat transfer to drag reductions is higher and is a function of the reduction level, but is approximately the same for polymer and surfactant solutions. This variation is consistent with the concept of a direct coupling through a nonunity constant Prt, as also suggested by our local measurements of temperature and velocity profiles. We also saw that our diameter scaling technique for friction applies equally well to heat transfer. These findings allow us to predict directly the heat transfer from friction measurements or vice versa for these drag-reducing fluids, and also suggest that a strong coupling exists between the heat and momentum transfer mechanisms.

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DIRECT NUMERICAL SIMULATION OF THE TURBULENT MOMENTUM AND HEAT TRANSFER IN AN INTERNALLY HEATED FLUID LAYER

Proceeding of International Heat Transfer Conference 7 ◽

10.1615/ihtc7.3020 ◽

1982 ◽

Cited By ~ 2

Author(s):

G. Grotzbach

Keyword(s):

Heat Transfer ◽

Numerical Simulation ◽

Direct Numerical Simulation ◽

Fluid Layer ◽

Momentum And Heat Transfer ◽

Heated Fluid ◽

Turbulent Momentum

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SHOCK WAVE INTERACTION NEAR A CYLINDER ALIGNED NORMAL TO A BLUNTED PLATE—PART I: GAS FLOW AND HEAT TRANSFER ON A PLATE NEAR A CYLINDER

TsAGI Science Journal ◽

10.1615/tsagiscij.2018026924 ◽

2018 ◽

Vol 49 (2) ◽

pp. 105-118

Author(s):

Volf Ya. Borovoy ◽

Vladimir Evguenyevich Mosharov ◽

Vladimir Nikolaevich Radchenko ◽

Arkadii Sergeyevich Skuratov

Keyword(s):

Heat Transfer ◽

Shock Wave ◽

Gas Flow ◽

Wave Interaction ◽

Shock Wave Interaction ◽

Flow And Heat Transfer

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Experimental analysis and ANN prediction on performances of finned oval-tube heat exchanger under different air inlet angles with limited experimental data

Open Physics ◽

10.1515/phys-2020-0212 ◽

2020 ◽

Vol 18 (1) ◽

pp. 968-980

Author(s):

Xueping Du ◽

Zhijie Chen ◽

Qi Meng ◽

Yang Song

Keyword(s):

Heat Transfer ◽

Experimental Data ◽

Heat Exchanger ◽

Correlation Equation ◽

Tube Heat Exchanger ◽

Flow Friction ◽

Air Inlet ◽

Comparison Results ◽

Wide Range ◽

Oval Tube

Abstract A high accuracy of experimental correlations on the heat transfer and flow friction is always expected to calculate the unknown cases according to the limited experimental data from a heat exchanger experiment. However, certain errors will occur during the data processing by the traditional methods to obtain the experimental correlations for the heat transfer and friction. A dimensionless experimental correlation equation including angles is proposed to make the correlation have a wide range of applicability. Then, the artificial neural networks (ANNs) are used to predict the heat transfer and flow friction performances of a finned oval-tube heat exchanger under four different air inlet angles with limited experimental data. The comparison results of ANN prediction with experimental correlations show that the errors from the ANN prediction are smaller than those from the classical correlations. The data of the four air inlet angles fitted separately have higher precisions than those fitted together. It is demonstrated that the ANN approach is more useful than experimental correlations to predict the heat transfer and flow resistance characteristics for unknown cases of heat exchangers. The results can provide theoretical support for the application of the ANN used in the finned oval-tube heat exchanger performance prediction.

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A Computational Study on the Role of Parameters for Identification of Thyroid Nodules by Infrared Images (and Comparison with Real Data)

Sensors ◽

10.3390/s21134459 ◽

2021 ◽

Vol 21 (13) ◽

pp. 4459

Author(s):

José R. González ◽

Charbel Damião ◽

Maira Moran ◽

Cristina A. Pantaleão ◽

Rubens A. Cruz ◽

...

Keyword(s):

Heat Transfer ◽

Thyroid Nodules ◽

Numerical Study ◽

Computational Study ◽

Internal Heat ◽

Heat Transfer Process ◽

The Body ◽

Physical Parameters ◽

Infrared Sensors ◽

Wide Range

According to experts and medical literature, healthy thyroids and thyroids containing benign nodules tend to be less inflamed and less active than those with malignant nodules. It seems to be a consensus that malignant nodules have more blood veins and more blood circulation. This may be related to the maintenance of the nodule’s heat at a higher level compared with neighboring tissues. If the internal heat modifies the skin radiation, then it could be detected by infrared sensors. The goal of this work is the investigation of the factors that allow this detection, and the possible relation with any pattern referent to nodule malignancy. We aim to consider a wide range of factors, so a great number of numerical simulations of the heat transfer in the region under analysis, based on the Finite Element method, are performed to study the influence of each nodule and patient characteristics on the infrared sensor acquisition. To do so, the protocol for infrared thyroid examination used in our university’s hospital is simulated in the numerical study. This protocol presents two phases. In the first one, the body under observation is in steady state. In the second one, it is submitted to thermal stress (transient state). Both are simulated in order to verify if it is possible (by infrared sensors) to identify different behavior referent to malignant nodules. Moreover, when the simulation indicates possible important aspects, patients with and without similar characteristics are examined to confirm such influences. The results show that the tissues between skin and thyroid, as well as the nodule size, have an influence on superficial temperatures. Other thermal parameters of thyroid nodules show little influence on surface infrared emissions, for instance, those related to the vascularization of the nodule. All details of the physical parameters used in the simulations, characteristics of the real nodules and thermal examinations are publicly available, allowing these simulations to be compared with other types of heat transfer solutions and infrared examination protocols. Among the main contributions of this work, we highlight the simulation of the possible range of parameters, and definition of the simulation approach for mapping the used infrared protocol, promoting the investigation of a possible relation between the heat transfer process and the data obtained by infrared acquisitions.

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Heat transfer characteristics of nanofluids from a sinusoidal corrugated cylinder placed in a square cavity

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211027208 ◽

2021 ◽

pp. 095440622110272

Author(s):

Salaika Parvin ◽

Nepal Chandra Roy ◽

Litan Kumar Saha ◽

Sadia Siddiqa

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Rayleigh Number ◽

Aspect Ratio ◽

Average Nusselt Number ◽

Numerical Study ◽

Heat Transfer Characteristics ◽

Number Range ◽

Transfer Characteristics ◽

Wide Range

A numerical study is performed to investigate nanofluids' flow field and heat transfer characteristics between the domain bounded by a square and a wavy cylinder. The left and right walls of the cavity are at constant low temperature while its other adjacent walls are insulated. The convective phenomena take place due to the higher temperature of the inner corrugated surface. Super elliptic functions are used to transform the governing equations of the classical rectangular enclosure into a system of equations valid for concentric cylinders. The resulting equations are solved iteratively with the implicit finite difference method. Parametric results are presented in terms of streamlines, isotherms, local and average Nusselt numbers for a wide range of scaled parameters such as nanoparticles concentration, Rayleigh number, and aspect ratio. Several correlations have been deduced at the inner and outer surface of the cylinders for the average Nusselt number, which gives a good agreement when compared against the numerical results. The strength of the streamlines increases significantly due to an increase in the aspect ratio of the inner cylinder and the Rayleigh number. As the concentration of nanoparticles increases, the average Nusselt number at the internal and external cylinders becomes stronger. In addition, the average Nusselt number for the entire Rayleigh number range gets enhanced when plotted against the volume fraction of the nanofluid.

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Mass and Heat Transfer Coefficients in Automotive Exhaust Catalytic Converter Channels

Catalysts ◽

10.3390/catal9060507 ◽

2019 ◽

Vol 9 (6) ◽

pp. 507

Author(s):

Chrysovalantis C. Templis ◽

Nikos G. Papayannakos

Keyword(s):

Heat Transfer ◽

Flow Reactor ◽

Catalytic Converter ◽

Reaction Rates ◽

Cfd Model ◽

Automotive Exhaust ◽

Transfer Coefficients ◽

Heat Transfer Coefficients ◽

Wide Range ◽

Mass And Heat Transfer

Mass and heat transfer coefficients (MTC and HTC) in automotive exhaust catalytic monolith channels are estimated and correlated for a wide range of gas velocities and prevailing conditions of small up to real size converters. The coefficient estimation is based on a two dimensional computational fluid dynamic (2-D CFD) model developed in Comsol Multiphysics, taking into account catalytic rates of a real catalytic converter. The effect of channel size and reaction rates on mass and heat transfer coefficients and the applicability of the proposed correlations at different conditions are discussed. The correlations proposed predict very satisfactorily the mass and heat transfer coefficients calculated from the 2-D CFD model along the channel length. The use of a one dimensional (1-D) simplified model that couples a plug flow reactor (PFR) with mass transport and heat transport effects using the mass and heat transfer correlations of this study is proved to be appropriate for the simulation of the monolith channel operation.

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