scholarly journals A CFD study on the evaporative cooling of a water droplet located in a duct

2021 ◽  
Vol 2 (1) ◽  
pp. 149-155
Author(s):  
Aref Khorammi ◽  
◽  
Amin Emamian ◽  
Sajjad Karimnejad ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Water Droplet ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Evaporative Cooling ◽  
Air Cooling ◽  
Dynamic Technique ◽  
The Mean ◽  
Insight Into ◽  
Study Offer

The current numerical study aimed for analayzing heat transfer of a spherical water droplet placed in a rectangular duct. The problem particularly deals with air-cooling of the droplet. The computational fluid dynamic technique is used to treat the problem. In order to study the problem, the effect of evaporation on the droplet's heat transfer is taken into consideration to make the problem more realistic. Moreover, various parameters like the inlet velocity and the temperature of the upstream are numerically checked. It is found out that with involving evaporation, the mean temperature of the droplets increases in comparison with the case that there is no evaporation involved. The outcomes of the current study offer useful and deep insight into the evaporative cooling of a water droplet.

scholarly journals On Efficient Estimation of Process Variability

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 554
Author(s):  
Tanveer Akhlaq ◽  
Muhammad Ismail ◽  
Muhammad Qaiser Shahbaz
Keyword(s):  
Numerical Study ◽  
Empirical Studies ◽  
Efficient Estimation ◽  
Process Variability ◽  
Good Insight ◽  
Exponential Method ◽  
Process Dispersion ◽  
The Mean ◽  
Insight Into ◽  
Better Than

Variability or dispersion plays an important role in any process and provides insight into the spread of data from some central point, usually the mean. A process with less spread is preferred over a process in which values differ greatly from the mean. Various methods are available to estimate the process dispersion by using information on the variable of interest. Certain additional variables provide good insight to estimate the process dispersion. In this paper, we propose an efficient method for the estimation of process variability by using the exponential method. The properties of the proposed method were studied. We conducted simulation and empirical studies to compare the proposed method with some existing methods of estimation of variability. The results of the numerical study show that our proposed method is better than the other methods used in the study.

Three-Dimensional Steady and Oscillatory Natural Convection in a Rectangular Enclosure With Heat Sources

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Amin Bouraoui ◽  
Rachid Bessaïh
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Three Dimensional ◽  
Air Cooling ◽  
Heat Sources ◽  
Rectangular Enclosure ◽  
Aspect Ratios ◽  
Simpler Algorithm ◽  
Strong Relation

In this paper, a numerical study of three-dimensional (3D) natural convection air-cooling of two identical heat sources, simulating electronic components, mounted in a rectangular enclosure was carried out. The governing equations were solved by using the finite-volume method based on the SIMPLER algorithm. The effects of Rayleigh number Ra, spacing between heat sources d, and aspect ratios Ax in x-direction (horizontal) and Az in z-direction (transversal) of the enclosure on heat transfer were investigated. In steady state, when d is increased, the heat transfer is more important than when the aspect ratios Ax and Az are reduced. In oscillatory state, the critical Rayleigh numbers Racr for different values of spacing between heat sources and their aspect ratios, at which the flow becomes time dependent, were obtained. Results show a strong relation between heat transfers, buoyant flow, and boundary layer. In addition, the heat transfer is more important at the edge of each face of heat sources than at the center region.

Numerical Study of Thermofluid Characteristics of a Double Spirally Coiled Tube Heat Exchanger

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Mahmoud Abdelmagied
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Curvature Ratio ◽  
Coiled Tube ◽  
Tube Heat Exchanger ◽  
Enhancing Heat Transfer

In this study, the thermofluid characteristics of double spirally coiled tube heat exchanger (DSCTHE) were investigated numerically. A three-dimensional (3D) computational fluid dynamic (CFD) model was developed using ansys 14.5 software package. To investigate the heat transfer and pressure drop characteristics of DSCTHE, the Realize k–ε turbulence viscous model had been applied with enhanced wall treatment for simulating the turbulent thermofluid characteristics. The governing equations were solved by a finite volume discretization method. The effect of coil curvature ratio on DSCTHE was investigated with three various curvature ratios of 0.023–0.031 and 0.045 for inner tube side and 0.024–0.032–0.047 for annular side. The effects of addition of Al2O3 nanoparticle on water flows inside inner tube side or annular side with different volume concentrations of 0.5%, 1%, and 2% were also presented. The numerical results were carried out for Reynolds number with a range from 3500 to 21,500 for inner tube side and from 5000 to 24,000 for annular side, respectively. The obtained results showed that with increasing coil curvature ratio, a significant effect was discovered on enhancing heat transfer in DSCTHE at the expense of increasing pressure drop. The results also showed that the heat transfer enhancement was increased with increasing Al2O3 nanofluid concentration, and the penalty of pressure drop was approximately negligible.

Influence of Non Uniform Boundary Conditions on Laminar Free Convection in Wavy Square Cavity With Partial Partitions

Volume 1 ◽  
2004 ◽  
Author(s):  
A. Sabeur-Bendehina ◽  
M. Aounallah ◽  
L. Adjlout ◽  
O. Imine ◽  
B. Imine
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Laminar Regime ◽  
Uniform Temperature ◽  
Square Cavity ◽  
Vertical Walls ◽  
The Mean ◽  
Rayleigh Numbers ◽  
Partial Partitions

In the present work, a numerical study of the effect of non uniform boundary conditions on the heat transfer by natural convection in cavities with partial partitions is investigated for the laminar regime. This problem is solved by using the partial differential equations which are the equation of mass, momentum and energy. The tests were performed for different boundary conditions and different Rayleigh numbers while the Prandtl number was kept constant. Four geometrical configurations were considered namely three and five undulations with increasing and decreasing partition length. The results obtained show that the non uniform temperature in the vertical walls affects the flow and the heat transfer. The mean Nusselt number decreases comparing with the heat transfer in the undulated square cavity without partitions for all non uniform boundary conditions tested.

Application of Air-Cooled Close-Loop Self-Circulation Evaporative Cooling System on Wind Power Generator

2012 ◽  
Vol 512-515 ◽  
pp. 675-678
Author(s):  
Jing Ming Li ◽  
Fu Chuan Song ◽  
Guo Biao Gu ◽  
Xin Dong Tian
Keyword(s):  
Heat Transfer ◽  
Critical Point ◽  
Wind Power ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Air Cooling ◽  
Power Generator ◽  
Wind Power Generator ◽  
Evaporative Cooling System ◽  
Large Wind

The application of evaporative cooling technology in the cooling of large wind power generator is a new attempt in the discovery of wind power energy. In some particular circumstances, the air-cooling condenser must be adopted as the secondary cooler in the evaporative cooling system of large wind generator. For the cooling medium in the air-cooling condenser is the air and the distribution of temperature is uneven along the cooling tube, so it’s necessary to do deep research on it. Experiments are carried out to study the heat transfer characteristics of the air-cooling condenser used in the Close-loop Self-circulating (CLSC) evaporative cooling system. The temperature distribution and the heat transfer can be acquired from the experiment. Thorough study is carried out on restart up of the close-loop evaporative cooling system of the wind power generator. Experiments are done in the laboratory and real wind power generator, and it’s found that there is a critical point in the restart up of the generator. Only if the flow head overcome the critical point can the wind power generator restart automatically. The result shows that heat transfer can be enhanced by some special method and the air-cooling condenser can satisfy the demand of the cooling system.

Free Convection in an Inclined Square Cavity With Partial Partitions on a Wavy Hot Wall

Volume 1 ◽  
2004 ◽  
Author(s):  
M. Belkadi ◽  
A. Azzi ◽  
O. Imine ◽  
L. Adjlout ◽  
M. Aounallah ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Numerical Study ◽  
Wavy Wall ◽  
Square Cavity ◽  
Inclination Angles ◽  
The Mean ◽  
Rayleigh Numbers ◽  
Partial Partitions ◽  
Wall Geometry

In the present investigation, a numerical study of the effect of the hot wavy wall with partial partitions on free convection in an inclined square cavity, differentially heated, was undertaken. This problem is solved by using the partial differential equations which are the equation of mass, momentum, and energy. The tests were performed for different inclination angles, partition lenghts and Rayleigh numbers while the Prandtl number was kept constant. A configuration with three undulations and three partitions has been tested. The results obtained show that the hot wall geometry with partions affects the heat transfer rate in the cavity. The mean Nusselt number decreases notably compared with the heat transfer in the square undulated cavity without partitions.

Numerical Study of the Velocity and Temperature Fields in a Flow-Through Reservoir

1976 ◽  
Vol 98 (3) ◽  
pp. 353-359 ◽  
Author(s):  
W. L. Oberkampf ◽  
L. I. Crow
Keyword(s):  
Heat Transfer ◽  
Wind Shear ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Vertical Plane ◽  
Short Wave ◽  
Temperature Fields ◽  
Wave Radiation ◽  
Long Wave ◽  
Flow Through

The fluid dynamic and temperature fields in a reservoir are numerically simulated by means of a finite difference procedure. The flow in the rectangular reservoir is assumed to be two-dimensional in a vertical plane. Inflow is allowed at the surface on one end of the reservoir and outflow occurs at any depth on the opposite end. The reservoir inflow is set at a given temperature and velocity so as to simulate the thermal discharge from a power generating facility. At the surface of the reservoir wind shear, short wave and long wave radiation, evaporation, and convective heat transfer are taken into account. The effects of inflow/outflow, wind shear, and heat transfer on the reservoir are discussed.

scholarly journals A Study of Rotor Cavities and Heat Transfer in a Cooling Process in a Gas Tubine

1992 ◽  
Author(s):  
R. S. Amano ◽  
V. Pavelic
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Flow ◽  
Numerical Study ◽  
Heat Transfer Process ◽  
High Rate ◽  
Turbulent Heat Transfer ◽  
Air Cooling ◽  
Turbulent Heat ◽  
Accurate Analysis

A high temperature flow through a gas-turbine produces a high rate of turbulent heat transfer between the fluid flow field and the turbine components. The heat transfer process through rotor disks causes thermal stress due to the thermal gradient as well as the centrifugal force causes mechanical stresses; thus an accurate analysis for the evaluation of thermal behavior is needed. This paper presents a numerical study of thermal flow analysis in a two-stage turbine in order to better understand the detailed flow and heat transfer mechanisms through the cavity and the rotating rotor-disks. The numerical computations were performed to predict thermal fields throughout the rotating disks. The method used in this paper is the ‘segregation’ method which requires a much smaller number of grids than actually employed in the computations. The results are presented for temperature distributions through the disk and the velocity fields which illustrate the interaction between the cooling air flow and gas flow created by the disk rotation. The temperature distribution in the disks shows a reasonable trend. The numerical method developed in this study shows that it can be easily adapted for similar computations for air cooling flow patterns through any rotating blade disks in a gas turbine.

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