Study of Buoyancy-Driven Flow Effect on Salt Gradient Solar Ponds Performance

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Shahram Derakhshan ◽  
Seyedeh Elnaz Mirazimzadeh ◽  
Syamak Pazireh
Keyword(s):  
Radiation Energy ◽  
Numerical Approach ◽  
Conservation Equation ◽  
Solar Ponds ◽  
One Dimensional ◽  
Energy Conservation Equation ◽  
Solar Pond ◽  
Salt Gradient ◽  
The Stability ◽  
Numerical Approaches

Salt gradient solar ponds are the ponds in which due to existence of saline and salt gradient layers, lower layers are denser and avoid the natural convection phenomenon to occur so that solar radiation energy can be stored in the lowest zone. In this study, one-dimensional (1D) and two-dimensional (2D) numerical approaches have been implemented to simulate unsteady buoyancy-driven flow of solar ponds. In 1D method, the pond has been investigated in terms of the layers thicknesses so that the variation of temperature is calculated by energy conservation equation. The formulized radiation term was used as energy source term in energy equation. The results of 1D approach were validated with an experimental study and then optimization was carried out to determine the maximum thermal efficiency for an interval of layers height. Since the stability of the solar pond cannot be determined by 1D simulation, a 2D approach was considered to show the stability for different nonconvective zone (NCZ) heights and different salt gradients. In 2D study, in order to investigate hydrodynamic and thermal behavior of saltwater fluid, a numerical approach was used to simulate temperature gradients throughout the pond. The results of 2D numerical method are validated with an experimental data. The effect of linear and nonlinear salt gradient was considered.

Effects of Friction and Extraction on the Stability of Solar Ponds

1983 ◽  
Vol 105 (4) ◽  
pp. 356-362 ◽  
Author(s):  
Y. S. Cha ◽  
W. T. Sha ◽  
S. L. Soo
Keyword(s):  
Experimental Results ◽  
Stability Criteria ◽  
Solar Ponds ◽  
Solar Pond ◽  
Salt Gradient ◽  
The Stability ◽  
Cellular Motion

Experimental results were compared to theoretical stability criteria of a salt gradient solar pond. Cellular motion in the nonconvective layer may be caused by instablity. Extension of stability criteria suggests use of stabilizing barriers via friction. Stability of longitudinal extraction assures optimum availability of energy from a solar pond.

Study on the Thermal Effect of Adding Coal Cinder to the LCZ of Solar Pond

2010 ◽  
Vol 42 ◽  
pp. 294-298
Author(s):  
Hua Wang ◽  
Jun Li Liu ◽  
Jia Ning Zou
Keyword(s):  
Normal Modes ◽  
Temperature Evolution ◽  
Small Scale ◽  
Large Area ◽  
Solar Ponds ◽  
Average Temperature ◽  
Solar Pond ◽  
Salt Gradient ◽  
Increasing Temperature

In this study, adding coal cinder to bottom of solar pond as a means of increasing temperature of the solar pond is presented. A series of small-scale tests are conducted in the simple mini solar ponds. These small-scale tests include the temperature evolution comparisons of this mode with other normal modes; the comparisons of the material added to LCZ and the comparisons of the different soaking times for coal cinder. In addition, a numerical calculation on predicting temperature evolution in large area of salt gradient solar pond is also given. Both of the experimental and numerical results suggest that adding porous media with low thermal diffusivity (e.g. coal cinder) could significantly increase the temperature in the vicinity of the bottom of the pond. From the view of long-term, this effect is supposed to enhance the average temperature of the solar pond.

Comparative Productivity of Distillation and Reverse Osmosis Desalination Using Energy From Solar Ponds

1982 ◽  
Vol 104 (4) ◽  
pp. 299-304 ◽  
Author(s):  
B. W. Tleimat ◽  
E. D. Howe
Keyword(s):  
Reverse Osmosis ◽  
Electrical Power ◽  
Water System ◽  
Rankine Cycle ◽  
Pond Water ◽  
Generator System ◽  
Solar Ponds ◽  
Solar Pond ◽  
Salt Gradient ◽  
Hydrocarbon Vapor

This paper presents comparative analyses of two methods for producing desalted water using the heat collected by a solar pond—the first by distillation, and the second by reverse osmosis. The distillation scheme uses a multiple-effect distiller supplied with steam generated in a flash boiler using heat from a solar pond. Solar pond water passes through a heat exchanger in the water system ahead of the flash boiler. The second scheme uses a similar arrangement to generate hydrocarbon vapor which drives a Rankine cycle engine. This engine produces mechanical/electrical power for the RO plant. The analyses use two pond water temperatures—82.2°C (180°F) and 71.1°C (160°F)—which seem to cover the range expected from salt-gradient ponds. In each case, the pond water temperature drops by 5.56°C (10°F) while passing through the vapor generator system. Results of these analyses show that, based on the assumptions made, desalted water could be produced by distillation at productivity rates much greater than those estimated for the RO plant.

scholarly journals Modeling of the Surface Convective Layer of Salt-Gradient Solar Ponds

1982 ◽  
Vol 104 (4) ◽  
pp. 293-298 ◽  
Author(s):  
Y. S. Cha ◽  
W. T. Sha ◽  
W. W. Schertz
Keyword(s):  
Double Diffusive Convection ◽  
Vertical Temperature ◽  
Solar Ponds ◽  
One Dimensional ◽  
Diffusive Convection ◽  
Combined Action ◽  
Salt Gradient ◽  
Wind Mixing ◽  
Convective Layer ◽  
Double Diffusive

A one-dimensional numerical model is developed to predict the diurnal variations of vertical temperature and concentration profiles in salt-gradient solar ponds. The model employs augmented thermal and mass diffusivities due to turbulent wind mixing and double-diffusive convection. Numerical results indicate that the thickness of the surface convective layer increases with wind speed (or the wavelength of the surface wave). Double-diffusive convection is, in the absence of wind, capable of sustaining a mixed layer at the surface when strong cooling occurs over the pond. In field ponds, the surface convective layer is probably maintained as a result of the combined action of wind-generated turbulent mixing and double-diffusive convection.

The Influence of Height of LCZ on the Salinity Diffusion of Solar Pond

2013 ◽  
Vol 448-453 ◽  
pp. 1521-1524
Author(s):  
Chun Juan Gao ◽  
Qi Zhang ◽  
Hai Hong Wu ◽  
Liang Wang ◽  
Xi Ping Huang
Keyword(s):  
Solar Energy ◽  
Fresh Water ◽  
Salt Water ◽  
Salinity Gradient ◽  
Good Method ◽  
Convective Zone ◽  
Solar Ponds ◽  
Solar Pond ◽  
Salt Gradient ◽  
And Diffusion

The solar ponds with a surface of 0.3m2were filled with different concentration salt water and fresh water. The three layer’s structure of solar ponds was formed in the laboratory ponds by using the salinity redistribution. The performance and diffusion of salinity were xperimentally in the solar pond. The measurements were taken and recorded daily at various locations in the salt-gradient solar pond during a period of 30 days of experimentation. The experimental results showed that the salinity gradient layer can sustain a longer time when the lower convective zone is thicker, which is benefit to store solar energy. Therefore, properly increasing the height of LCZ is a good method to enhance the solar pond performance.

Experimental Study on Solar Ponds Combination with Solar Collector

2011 ◽  
Vol 347-353 ◽  
pp. 174-177 ◽  
Author(s):  
Dan Wu ◽  
Hong Sheng Liu ◽  
Wen Ce Sun
Keyword(s):  
Experimental Study ◽  
Solar Radiation ◽  
Solar Collector ◽  
Experimental Period ◽  
Convective Zone ◽  
Ambient Conditions ◽  
Solar Ponds ◽  
Ambient Temperatures ◽  
Solar Pond ◽  
Salt Gradient

The performance of Salt-gradient solar ponds (SGSP) with and without the solar collector are investigated experimentally in this paper. Two mini solar ponds with same structure are built, and one the them is appended with an exceptive solar collector for compared study. The salinity, temperature and turbidity of solar pond are studied contrastively for the two solar ponds under the same ambient conditions. The ambient temperatures,humidity and solar radiation are investigated during the experimental period. It was found that the temperature of the lower convective zone in the solar pond coupled with a solar collector increases by about 20% due to the introduce of solar collector.

The stability of an unsustained salt gradient solar pond

1998 ◽  
Vol 13 (4) ◽  
pp. 543-548 ◽  
Author(s):  
R. Jayaprakash ◽  
K. Perumal
Keyword(s):  
Solar Pond ◽  
Salt Gradient ◽  
The Stability

Parametric Study of Salt Gradient Solar Ponds

1986 ◽  
Vol 108 (1) ◽  
pp. 75-77 ◽  
Author(s):  
R. S. Beniwal ◽  
N. S. Saxena ◽  
R. C. Bhandari
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Parametric Study ◽  
Heat Losses ◽  
Insulating Materials ◽  
Solar Ponds ◽  
Solar Pond ◽  
Salt Gradient

A mathematical model for efficiency of a salt gradient solar pond is described. Heat losses from the bottom of the pond have been calculated, and the results for the effective thermal conductivity with the thicknesses of various insulating materials have been presented. The effect of the ground thermal resistance on the efficiency of the pond for different values of ΔT/So have also been shown.

A Halo-Thermal Simulation of the Dead Sea for Application to Solar Energy Projects

1983 ◽  
Vol 105 (4) ◽  
pp. 348-355 ◽  
Author(s):  
P. Vadasz ◽  
D. Weiner ◽  
Y. Zvirin
Keyword(s):  
Dead Sea ◽  
Solar Ponds ◽  
One Dimensional ◽  
Finite Differences Method ◽  
Energy Projects ◽  
Transfer Equations ◽  
Salt Gradient ◽  
The Dead ◽  
Large Water ◽  
Engineering Projects

A one-dimensional numerical model is developed to predict the long-range variations of vertical temperature, density, and salinity profiles in the Dead Sea, which is a highly saline large water body. The model utilizes the continuity, momentum, energy, and mass transfer equations, while taking into account the influence of the wind. The partial differential equations were solved numerically by means of explicit finite differences method. Simulation results were verified by comparison to measured data. In addition, the algorithm evaluates the evaporation rate from the Dead Sea which is an important parameter in several engineering projects under planning, such as the Mediterranean-Dead Sea conduit and the construction of floating salt gradient solar ponds for power generation.

Contact Drying of a Sheet of Moist Fibrous Material

1980 ◽  
Vol 102 (1) ◽  
pp. 8-12 ◽  
Author(s):  
D. W. Lyons ◽  
C. T. Vollers ◽  
A. M. ElNashar
Keyword(s):  
Porous Materials ◽  
Fibrous Material ◽  
Conservation Equation ◽  
One Dimensional ◽  
Finite Difference Technique ◽  
Energy Conservation Equation ◽  
Contact Drying ◽  
Drying Model ◽  
Analytical Expressions ◽  
Moist Porous Material

Drying processes consume a significant part of processing time and costs in the manufacture of papers, textiles, ceramics and other porous materials. An analysis was made of the phenomena constituting drying processes for porous materials and analytical expressions developed to describe the internal processes and boundary conditions. The analysis considered the departure from thermodynamic equilibrium associated with evaporation or condensation. The mass and energy conservation equation in one-dimensional form was solved by the finite difference technique. The results of this mathematical drying model were compared with the experimental data of Cowan [2] for the case of the drying of a disc-shaped mat. On the basis of this comparison, it was concluded that the analytical model is satisfactory for predicting the moisture and temperature distribution in moist porous material during drying.

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