Numerical study on impacting-freezing process of the droplet on a lateral moving cold superhydrophobic surface

Abstract We numerically investigate the melting and solidi?cation behavior of phase change materials encapsulated in a small-radii cylinder subjected to a cyclic convective boundary condition (square wave). Initially, we explore the effect of the Stefan and Biot numbers on the non-dimensionalized time required (i.e. reference Fourier number Tref ) for a PCM initially held at Tcold to melt and reach the cross?ow temperature Thot. The increase in either Stefan or Biot number decreases Tref and can be predicted accurately using a correlation developed in this work. The variations of the PCM melt fraction, surface temperature, and heat transfer rate as a function of Fourier number are reported and analyzed for the above process. We further study the effect of the cyclic Fourier number on the periodic melting and freezing process. The melting or freezing front initiates at the outer periphery of the PCM and propagates towards the center. At higher frequencies, multiple two-phase interfaces are generated (propagating inward), and higher overall heat transfer is achieved as the surface temperature oscillates in the vicinity of the melting temperature, which increases the effective temperature difference driving the convective heat transfer.

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Cooling and Freezing of Cashew Apple Using Computational Fluid Dynamics

Diffusion Foundations ◽

10.4028/www.scientific.net/df.25.114 ◽

2020 ◽

Vol 25 ◽

pp. 114-132 ◽

Cited By ~ 1

Author(s):

V.A. Agra Brandão ◽

R. Araújo de Queiroz ◽

R. Lima Dantas ◽

G. Santos de Lima ◽

N. Lima Tresena ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Nutritional Value ◽

Fruits And Vegetables ◽

Numerical Study ◽

Freezing Process ◽

Ansys Cfx ◽

Cashew Apple ◽

Freezing Period ◽

Kinetics Of

Freezing is one the most efficient methods for conservation, especially, fruits and vegetables. Cashew is a fruit with high nutritional value and great economic importance in the Northeast region of Brazil, however, due to high moisture content, it is highly perishable. The numerical study of the freezing process is of great importance for the optimization of the process. In this sense, the objective of this work was to study the cooling and freezing processes of cashew apple using computational fluid dynamics technique. Experiments of cooling and freezing of the fruit, with the aid of a refrigerator,data acquisition system and thermocouples, and simulation using Ansys CFX® software for obtain the cooling and freezing kinetics of the product were realized. Results of the cooling and freezing kinetics of the cashew apple and temperature distribution inside the cashew apple are presented, compared and analyzed. The model was able to predict temperaturetransient behavior with good accuracy, except in the post-freezing period.

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Droplet impingement on nano-textured superhydrophobic surface: Experimental and numerical study

Applied Surface Science ◽

10.1016/j.apsusc.2019.06.104 ◽

2019 ◽

Vol 491 ◽

pp. 160-170 ◽

Cited By ~ 8

Author(s):

Jian Qu ◽

Yaolin Yang ◽

Shusheng Yang ◽

Dinghua Hu ◽

Huihe Qiu

Keyword(s):

Superhydrophobic Surface ◽

Numerical Study ◽

Droplet Impingement

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Measurement and Numerical Study of Characteristics of an Energy Unit

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.568-570.1774 ◽

2014 ◽

Vol 568-570 ◽

pp. 1774-1777

Author(s):

Zhen Bao Sun

Keyword(s):

Experimental Data ◽

Numerical Study ◽

Freezing Process ◽

Freezing Time ◽

Energy Unit ◽

Practical Engineering ◽

Explicit Finite Difference ◽

The Mathematical Model ◽

Perform Computer Simulation ◽

Explicit Finite Difference Method

The mathematical model based on temperature formulation for describing freezing course of soil is presented and the explicit finite difference method is used to perform computer simulation of freezing time of soil in this paper. It seems to be satisfactory by comparing the numerical results by the method of TDMA with experimental data. It is significant for freezing process and freezing units, optimum design of practical engineering.

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Numerical Study on Microwave Dehydro-Freezing of Fish Tissues

ASME/JSME 2011 8th Thermal Engineering Joint Conference ◽

10.1115/ajtec2011-44463 ◽

2011 ◽

Author(s):

Yuichiro Oku ◽

Hirofumi Tanigawa ◽

Takaharu Tsuruta

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Numerical Study ◽

Fish Tissue ◽

Cell System ◽

Moisture Distribution ◽

Freezing Process ◽

Tissue Cell ◽

Frozen Fish ◽

Fundamental Equations

In this study, a numerical simulation on the freezing process is carried out to evaluate the effects of pre-dehydration on the quality of frozen fish tissue. We use a simulation model which contains a muscle fiber to express the microscale heat and mass transfer phenomena inside the tissue cell system. Fundamental equations on heat and mass transfer are formulated in a two-dimensional coordinate system. The governing equations include phase-change terms. In order to take account of the characteristic moisture distribution produced by the microwave room-temperature drying, initial moisture distributions are given in this calculation. The numerical results indicate that the control of the water content by the pre-dehydration can shorten the freezing time. It is found that the cell shrinkage ratio is larger than that of the result using uniform distribution. As an increase of pre-dehydration, the central cell significantly shrinks but the surface-layer cell doesn’t shrink so much due to the large cooling rate.

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Three-Dimensional Numerical Study on Freezing Phase Change Heat Transfer in Biological Tissue Embedded With Two Cryoprobes

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4004425 ◽

2011 ◽

Vol 3 (3) ◽

Cited By ~ 1

Author(s):

Fang Zhao ◽

Zhenqian Chen

Keyword(s):

Heat Transfer ◽

Phase Change ◽

Biological Tissue ◽

Clinical Medicine ◽

Numerical Study ◽

Biological Tissues ◽

Freezing Process ◽

Ice Crystal ◽

Obvious Effect ◽

Phase Change Heat Transfer

Biological tissues undergo complex phase change heat transfer processes during cryosurgery, and a theoretical model is preferable to forecast this heat experience. A mathematical model for phase change heat transfer in cryosurgery was established. In this model, a fractal treelike branched network was used to describe the complicated geometrical frame of blood vessels. The temperature distribution and ice crystal growth process in biological tissue including normal tissue and tumor embedded with two cryoprobes were numerically simulated. The effects of cooling rate, initial temperature, and distance of two cryoprobes on freezing process of tissue were also studied. The results show that the ice crystal grows more rapidly in the initial freezing stage (<600 s) and then slows down in the following process, and the precooling of cryoprobes has no obvious effect on freezing rate of tissue. It also can be seen that the distance of 10 mm between two cryoprobes produces an optimal freezing effect for the tumor size (20 mm × 10 mm) in the present study compared with the distances of 6 mm and 14 mm. The numerical results are significant in providing technical reference for application of cryosurgery in clinical medicine.

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Pulsating Flow of a Viscous Fluid over a Cavity Containing a Compressible Gas Bubble

Fluid Dynamics ◽

10.1134/s001546282106001x ◽

2021 ◽

Vol 56 (6) ◽

pp. 799-811

Author(s):

A. I. Ageev ◽

A. N. Osiptsov

Keyword(s):

Viscous Fluid ◽

Superhydrophobic Surface ◽

Numerical Study ◽

Plane Channel ◽

Velocity Slip ◽

Pulsating Flow ◽

Friction Reduction ◽

Gas Bubble ◽

Viscous Boundary Layer ◽

Compressible Gas

A two-dimensional pulsating flow of a viscous fluid in a plane channel whose wall has rectangular microcavities partially or completely filled with a compressible gas is investigated. This problem formulation can clarify the friction reduction mechanism in a laminar sublayer of a turbulent viscous boundary layer flow over a textured stripped superhydrophobic surface containing periodically arranged rectangular micro-cavities filled with gas. It is assumed that the dimensions of the cavities are much smaller than the channel thickness. On the macroscale, the problem of one-dimensional unsteady viscous flow in a plane channel with no-slip conditions on the walls and a harmonic variation of the pressure difference is solved. The solution obtained in this way is used for formulating non-stationary in time and periodic in space boundary conditions for the flow on the scale of a chosen cavity (microscale), with the instantaneous volume of the gas bubble in the cavity depending on the instantaneous pressure over the cavity. The flow on the microscale near a cavity with a gas bubble occurs in the Stokes regime. The numerical solution is obtained using an original version of the boundary element method. A parametric numerical study of the flow field in a pulsating shear flow over a cavity with a compressible gas bubble is performed. The averaged parameters characterizing the effective ‘velocity slip’ of viscous fluid and the friction reduction in a pulsating flow over a stripped superhydrophobic surface are calculated.

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