Experimental and Numerical Study of Transport Phenomena in a Simulated Hydrothermal Crystal Growth System of Fluid-Saturated Porous Layer

2000 ◽  
Author(s):  
D. Mishra ◽  
A. Pal ◽  
N. Nemick ◽  
A. K. Saha ◽  
V. Prasad ◽  
...  
Keyword(s):  
Temperature Field ◽  
Porous Layer ◽  
Hydrothermal System ◽  
Numerical Study ◽  
Transport Phenomena ◽  
Composite Layer ◽  
Staggered Grid ◽  
Working Fluid ◽  
Hydrothermal Crystal Growth ◽  
Numerical Predictions

Abstract A simulated, non-pressurized hydrothermal system consisting of a fluid-superposed porous layer is fabricated and used for visualization and measurement of the temperature field using liquid crystal thermography. The system is used for various boundary conditions with pure glycerine as the working fluid and the porous layer is made of 3mm diameter glass beads. Experimental data is recorded using a color CCD camera and flow visualization is obtained through a long exposure video photography. A calibration is performed to relate the temperature with scattered colors at an orthogonal angle to the incoming white light sheet. Quantitative temperature data is obtained through this calibration and compared with the numerical predictions. For numerical studies the system is modeled as a composite layer of fluid and porous charge using the Darcy-Brinkman-Forchheimer flow model. A two-dimensional curvilinear algorithm using finite volume technique with a non-staggered grid is used to simulate the temperature field and transport phenomena for various Rayleigh–Darcy number combinations of varying aspect ratio. The results, for the first time, make an attempt towards understanding the transport process in hydrothermal system through both numerical simulation and experimental validation.

scholarly journals Experimental and Numerical Study on Energy Piles with Phase Change Materials

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4699 ◽  
Author(s):  
M. M. Mousa ◽  
A. M. Bayomy ◽  
M. Z. Saghir
Keyword(s):  
Phase Change ◽  
Heat Pump ◽  
Flow Rate ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Numerical Predictions ◽  
Energy Piles ◽  
Discharging Capacity

Phase change materials (PCM) utilization in energy storage systems represents a point of interest and attraction for the researchers to reduce greenhouse gas emissions. PCM have been used widely on the interior or exterior walls of the building application to optimize the energy consumption during heating and cooling periods. Meanwhile, ground source heat pump (GSHP) gained its popularity because of the high coefficient of performance (COP) and low running cost of the system. However, GSHP system requires a stand-by heat pump during peak loads. This study will present a new concept of energy piles that used PCM in the form of enclosed tube containers. A lab-scaled foundation pile was developed to examine the performance of the present energy pile, where three layers of insulation replaced the underground soil to focus on the effect of PCM. The investigation was conducted experimentally and numerically on two identical piles with and without PCM. Moreover, a flow rate parametric study was conducted to study the effect of the working fluid flow rate on the amount of energy stored and released at each model. Finally, a comprehensive Computational fluid dynamic (CFD) model was developed and compared with the experimental results. There was a good agreement between the experimental measurements and the numerical predictions. The results revealed that the presence of PCM inside the piles increased not only the charging and discharging capacity but also the storage efficiency of the piles. It was found that PCM enhances the thermal response of the concrete during cooling and heating processes. Although increasing the flow rate increased charging and discharging capacity, the percentage of energy stored/released was insignificant compared to the flow rate increasing percentage.

A Numerical and Experimental Study of Laminar Unsteady Lid-Driven Cavity Flows

2017 ◽  
Author(s):  
K. M. Akyuzlu
Keyword(s):  
Experimental Study ◽  
Steady State ◽  
Flow Field ◽  
Numerical Study ◽  
Working Fluid ◽  
Cavity Flows ◽  
Square Cavity ◽  
Measured Velocity ◽  
Driven Cavity ◽  
Numerical Predictions

An experimental and numerical study was conducted to study unsteady lid-driven cavity flows. More specifically, the development of the circulation patterns inside a square cavity due to the movement of a rigid impermeable lid at constant velocity was observed experimentally and predicted numerically by CFD codes. Particle Image Velocimeter (PIV) technique was used to determine the flow field as it develops from stagnation to steady state inside a one inch (25.4 mm) square cavity driven by an impermeable lid. To avoid the three dimensional effects on the primary vortex, the depth of the cavity is taken to be 5 inches (127 mm). Working fluid is water and it is seeded with hallow glass spheres with 10 microns diameter. Experimental study was conducted for different lid velocities corresponding to Reynolds numbers for laminar to intermittent turbulence. The numerical study was carried out using commercial and in-house CFD codes for the steady state case, and using a commercial CFD code for the unsteady case. The predictions of unsteady flow field inside the two-dimensional square cavity were made using these codes which employ second order accurate (temporally and spatially) implicit numerical schemes. A time and mesh independence study was carried out to determine the optimum mesh size and time increment for the unsteady case study. Comparisons of the numerically predicted and experimentally measured velocity fields are made for steady and unsteady cases. The results indicate that the numerical predictions capture the characteristics of the circulation inside the cavity reasonably well however the magnitude of the velocities are underestimated.

Numerical Study of a Solar-Powered Stirling Engine With a Transparent Top Cover

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
E. Sanmiguel-Rojas ◽  
P. Gutierrez-Castillo ◽  
J. A. Auñón-Hidalgo
Keyword(s):  
Porous Layer ◽  
Engine Speed ◽  
Numerical Study ◽  
Stirling Engine ◽  
Working Fluid ◽  
Expansion Chamber ◽  
Engine Efficiency ◽  
Wire Screen ◽  
Absorbing Layer ◽  
Solar Powered

Abstract The present work is focused on the numerical study of a solar-powered Stirling engine, with the particularity that the solar radiation is injected through a transparent top cover. Thus, the working fluid absorbs the heat across a porous layer of a steel woven wire screen placed alongside the inner side of the transparent wall. The engine output net power and efficiency are studied as a function of the porosity, engine speed, temperature of the expansion chamber, and wire diameter of the screen. It is found that the engine efficiency remains practically constant for porosity values over 0.7, but there is a relevant increase of the engine output net power compared to the same working conditions without the absorbing layer. For a given porosity value, the most significant increase of net power due to introducing the porous layer was reached when doubling the engine speed resulting in an increment close to 40%.

Numerical Study of Transient Conjugate Heat Transfer in a Long Two-Phase Pipeline

2000 ◽  
Author(s):  
Yuri V. Fairuzov ◽  
Hector Arvizu Dal Piaz
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Conjugate Heat Transfer ◽  
Pipe Wall ◽  
Numerical Study ◽  
Electrical Heating ◽  
Practical Significance ◽  
Local Thermal Equilibrium ◽  
Working Fluid ◽  
Two Phase

Abstract A growing number of multiphase technology applications stimulate the development of reliable methods for modeling transient processes in two-phase systems in which the temperature field in the moving fluid and the temperature field in the bounding walls are directly dependent on each other. This situation presents a conjugate heat-transfer problem since the heat-transfer rate at the wall-fluid interface and local fluid conditions are not known a priori, and therefore need to be simultaneously calculated. Examples of such processes include the direct heating of multiphase pipelines, a change of heat load in evaporators of two-phase thermal control systems, startup or shutdown of systems with a two-phase working fluid. In this paper, direct electrical heating of a long two-phase pipeline has been modeled. The modeling of transient two-phase flow and heat transfer in the pipeline is based on two different mathematical formulations. In the first formulation, the transient heat conduction and the forced convection effects are rigorously taken into account. The second formulation assumes that the pipe wall and the fluid are in local thermal equilibrium. The effect of the thermal capacity of the pipe wall is taken into account by an additional term in the energy equation for the fluid flow. Such an approach allows significant simplifying the problem and reducing the computer running time. Numerical simulation of the sudden heat input to the pipe wall has been performed using both formulations of field equations. The practical significance of the results obtained is discussed.

USAGE OF A DIATOMITE-CONTAINING NANOFLUID AS THE WORKING FLUID IN A WICKLESS LOOP HEAT PIPE: EXPERIMENTAL AND NUMERICAL STUDY

2018 ◽  
Vol 49 (17) ◽  
pp. 1721-1744 ◽  
Author(s):  
Adnan Sözen ◽  
Erdem Çiftçi ◽  
Selçuk Keçel ◽  
Metin Gürü ◽  
Halil Ibrahim Variyenli ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Numerical Study ◽  
Working Fluid ◽  
Loop Heat Pipe

Numerical study of the flow of a mixture of reacting gases in an inhomogeneous catalyst layer

2003 ◽  
Vol 3 ◽  
pp. 246-254
Author(s):  
C.I. Mikhaylenko ◽  
S.F. Urmancheev
Keyword(s):  
Velocity Field ◽  
Chemical Reactions ◽  
Porous Layer ◽  
Computational Experiment ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Catalyst Layer ◽  
Granular Catalyst ◽  
Fluid Velocity Field

The behavior of a liquid flowing through a fixed bulk porous layer of a granular catalyst is considered. The effects of the nonuniformity of the fluid velocity field, which arise when the surface of the layer is curved, and the effect of the resulting inhomogeneity on the speed and nature of the course of chemical reactions are investigated by the methods of a computational experiment.

Experimental and Numerical Study of Methanol-Water Mixture Single-Phase Heat Transfer in a Micro-Channel Heat Sink

2012 ◽  
Author(s):  
Chun K. Kwok ◽  
Matthew M. Asada ◽  
Jonathan R. Mita ◽  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Numerical Study ◽  
Pure Water ◽  
Molar Fraction ◽  
Water Mixture ◽  
Micro Channel ◽  
Numerical Predictions

This paper presents an experimental study of single-phase heat transfer characteristics of binary methanol-water mixtures in a micro-channel heat sink containing an array of 22 microchannels with 240μm × 630μm cross-section. Pure water, pure methanol, and five methanol-water mixtures with methanol molar fraction of 16%, 36%, 50%, 63% and 82% were tested. Key parametric trends were identified and discussed. The experimental study was complemented by a three-dimensional numerical simulation. Numerical predictions and experimental data are in good agreement with a mean absolute error (MAE) of 0.87%.

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