Assessing the Maximum Stability of the Nonconvective Zone in a Salinity-Gradient Solar Pond

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
A. A. Abdullah ◽  
K. A. Lindsay
Keyword(s):  
Salinity Gradient ◽  
Fluid Velocity ◽  
Weather Conditions ◽  
Convective Zone ◽  
Heat Extraction ◽  
Solar Pond ◽  
Maximum Stability ◽  
Storage Zone ◽  
The Stability

The quality of the stability of the nonconvective zone of a salinity-gradient solar pond (SGSP) is investigated for an operating protocol in which the flushing procedure exactly compensates for evaporation losses from the solar pond and its associated evaporation pond. The mathematical model of the pond uses simplified, but accurate, constitutive expressions for the physical properties of aqueous sodium chloride. Also, realistic boundary conditions are used for the behaviors of the upper and lower convective zones (LCZs). The performance of a salinity-gradient solar pond is investigated in the context of the weather conditions at Makkah, Saudi Arabia, for several thickness of upper convective zone (UCZ) and operating temperature of the storage zone. Spectral collocation based on Chebyshev polynomials is used to assess the quality of the stability of the pond throughout the year in terms of the time scale for the restoration of disturbances in temperature, salinity, and fluid velocity underlying the critical eigenstate. The critical eigenvalue is found to be real and negative at all times of year indicating that the steady-state configuration of the pond is always stable, and suggesting that stationary instability would be the anticipated mechanism of instability. Annual profiles of surface temperature, salinity, and heat extraction are constructed for various combinations for the thickness of the upper convective zone and storage zone temperature.

Effect of Water Distribution Ways on the Operation of Solar Pond

2013 ◽  
Vol 805-806 ◽  
pp. 74-77
Author(s):  
Chun Juan Gao ◽  
Qi Zhang ◽  
Liang Wang ◽  
Ying Wang ◽  
Xi Ping Huang
Keyword(s):  
Water Distribution ◽  
Salinity Gradient ◽  
Convective Zone ◽  
The Body ◽  
Solar Ponds ◽  
Solar Pond ◽  
Storage Zone ◽  
Small Model ◽  
Laboratory Tank ◽  
Salt Diffusion

An experimental study on the evolution of the salinity profiles in the salinity gradient solar ponds was executed using a small model pond. The body of the simulated pond is a cylindrical plastic tank, with 50 cm height and 45 cm diameter. The salinity gradient was established in the laboratory tank by using the salinity redistribution technique. The measurements were taken during a period of 20 days of experimentation. This period of time allowed the existence of salt diffusion from the storage zone to the surface. Results obtained from this study show that when the ratio of brine/water is 1/1, the salinity gradient layer can sustain a longer time and the lower convective zone is thicker, which is benefit to store solar energy.

Concept of Triple Heat Exchanger-Assisted Solar Pond Through an Improved Analytical Model

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Sunirmit Verma ◽  
Ranjan Das
Keyword(s):  
Analytical Model ◽  
Power Output ◽  
Heat Exchangers ◽  
Thermal Power ◽  
Convective Zone ◽  
Heat Extraction ◽  
Extraction System ◽  
Seepage Water ◽  
Solar Pond ◽  
Bottom Zone

A new three-zone heat extraction system and its analytical model for maximizing the thermal power output of salt gradient solar ponds against a given volume is proposed. The present study considers internal heat exchangers installed within the non-convective zone (NCZ), lower-convective zone (LCZ), and the ground below the pond. The work is validated against a simplified version of the model (eliminating ground and bottom-zone heat extractions) available in the existing literature. Contrary to the conventional practice of optimizing only the middle-zone pond thickness, here, the newly proposed expression is used to find ideal values of both the middle- and bottom-zone thicknesses of the pond along with its cross-sectional area. The present work acknowledges that although the three-zone heat extraction system is the best, yet if a choice for two-zone heat extraction is to be made between the NCZ–LCZ and ground–LCZ, then the former is a better alternative. The power output is observed to increase asymptotically with mass flow rates of the three heat exchangers. However, their values must lie much below their theoretical asymptotic limits and their selection is regulated by constructional and operational constraints. These involve a minimum pond depth to offset surface evaporation, ground seepage water loss, and constraints preventing turbulent flow in heat exchangers to reduce friction loss and pumping power. This work recommends using three heat exchangers instead of either one or two and provides cardinal guidelines to extract heat in an ideal manner for a fixed solar pond volume.

El Paso Solar Pond

2001 ◽  
Vol 123 (3) ◽  
pp. 178-178 ◽  
Author(s):  
Huanmin Lu and ◽  
Andrew H. P. Swift
Keyword(s):  
Systems Approach ◽  
Salinity Gradient ◽  
El Paso ◽  
Industrial Process ◽  
The United States ◽  
Convective Zone ◽  
Bureau Of Reclamation ◽  
University Of Texas ◽  
Solar Pond ◽  
Brine Management

The El Paso Solar Pond, a research, development, and demonstration project operated by the University of Texas at El Paso, is a salinity-gradient solar pond with a surface area of 3,000 m2 and a depth of 3.2 m. The pond utilizes an aqueous solution of predominantly sodium chloride (NaCl). The surface convective zone, main gradient zone, and bottom convective zone are approximately 0.6 m, 1.4 m, and 1.2 m, respectively. The project, located on the property of Bruce Foods, Inc., was initiated in 1983 in cooperation with the U.S. Bureau of Reclamation. Since then, the El Paso Solar Pond has successfully developed a series of technologies for solar pond operation and maintenance, as well as demonstrated several different applications. In 1985, the El Paso Solar Pond became the first in the world to deliver industrial process heat to a commercial manufacturer; in 1986 became the first solar pond electric power generating facility in the United States; and in 1987 became the nation’s first experimental solar pond powered water desalting facility. Currently, the major research at El Paso Solar Pond is focused on desalination and brine management technologies. The long-term goal of this research is to develop a systems approach for desalination/brine management via a multiple process desalination coupled with solar ponds. This systems approach will reuse the brine concentrate rejected from desalting plants thereby negating the need for disposal (zero discharge), and provide additional pollution-free renewable energy for the desalting process.

scholarly journals A theoretical and numerical study of thermosolutal convection: stability of a salinity gradient solar pond

2011 ◽  
Vol 15 (1) ◽  
pp. 67-80 ◽  
Author(s):  
Dalila Akrour ◽  
Mouloud Tribeche ◽  
Djamel Kalache
Keyword(s):  
Stability Analysis ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Salinity Gradient ◽  
Thermosolutal Convection ◽  
Separation Coefficient ◽  
Onset Of Convection ◽  
Solar Pond ◽  
Negative Case ◽  
The Stability

A theoretical and numerical study of the effect of thermodiffusion on the stability of a gradient layer is presented. It intends to clarify the mechanisms of fluid dynamics and the processes which occur in a salinity gradient solar pond. A mathematical modelling is developed to describe the thermodiffusion contribution on the solar pond where thermal, radiative, and massive fluxes are coupled in the double diffusion. More realistic boundary conditions for temperature and concentration profiles are used. Our results are compared with those obtained experimentally by authors without extracting the heat flux from the storage zone. We have considered the stability analysis of the equilibrium solution. We assumed that the perturbation of quantities such as velocity, temperature, and concentration are infinitesimal. Linearized equations satisfying appropriate prescribed boundary conditions are then obtained and expanded into polynomials form. The Galerkin method along with a symbolic algebra code (Maple) are used to solve these equations. The effect of the separation coefficient y is analyzed in the positive and negative case. We have also numerically compared the critical Rayleigh numbers for the onset of convection with those obtained by the linear stability analysis for Le = 100, ?a = 0.8, and f = 0.5.

Heat extraction and brine management from salinity gradient solar pond and membrane distillation

2017 ◽  
Vol 118 ◽  
pp. 226-237 ◽  
Author(s):  
Kamran Manzoor ◽  
Sher Jamal Khan ◽  
Yousuf Jamal ◽  
Muhammad Aamir Shahzad
Keyword(s):  
Salinity Gradient ◽  
Membrane Distillation ◽  
Heat Extraction ◽  
Solar Pond ◽  
Brine Management

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.

scholarly journals Effect of Different Parameters on Solar Pond Performance

2014 ◽  
Vol 1 (1) ◽  
pp. 54-70
Author(s):  
Seyed Saeed Madani
Keyword(s):  
Storage Capacity ◽  
Operating Temperature ◽  
Global Radiation ◽  
Convective Zone ◽  
Heat Extraction ◽  
Variable Loading ◽  
Practical Applications ◽  
Loading Pattern ◽  
Solar Pond ◽  
Operational Temperature

By applying a model of finite differences, the thermal behavior of a large solar pond is studied in this paper. The 32-year data of sunny hour’s today-length ratio are used for the estimation of global radiation. The temperature data of a similar duration are used for evaluating the ambient temperature. The effects of the variation of different zone thicknesses on pond performance are studied. It is observed that the upper convective zone thickness should be as thin as possible, the non-convective zone might be from 1 to 2 m and the lower convective zone thickness may be designed based on the application needs. A thicker non convective zone provides more insulation against heat losses, and a thicker lower convective one supplies a higher storage capacity, though with a lower operating temperature. The heat may be extracted from the pond by either a constant or a variable loading pattern. The appropriate loading pattern can be selected based on the needs and operational temperature. The LCZ temperature of the pond, under several heat extraction patterns, is also presented for practical applications.            

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