A Comparison between Evaporation Ponds and Evaporation Surfaces as a Source of the Concentrated Salt Brine for Salt Gradient Maintenance at Tajoura’s Solar Pond

Abdulghani   Ramadan; Khairy    Agha; Saleh    Abughres

doi:10.51646/jsesd.v2i1.94

Authors

Abdulghani M. Ramadan Mechanical Eng. Dept., Al-Mergib University, Libya
Khairy R. Agha Renewable Energy Authority of Libya
Saleh M. Abughres Faculty of Engineering, University of Tripoli, Tripoli-Libya

DOI:

https://doi.org/10.51646/jsesd.v2i1.94

Keywords:

Solar pond , Evaporation , Evaporation pond , Evaporation surface , Salinity profie , Area ratio , Concentration

Abstract

One of the main problems that negatively affect the operation of salt gradient solar ponds and influence its thermal stability is the maintenance of salt gradient profile Evaporation pond (EP) is designed to generate the salt which is lost by upward salt diffusion
from the lower convective zone (LCZ) of the solar pond. Another attractive method is the Evaporation Surface facility (ES). Regions with moderate to high precipitation favor Evaporation Surfaces over Evaporation Ponds. Dry climates will generally favor Evaporation Ponds for the brine re-concentration. In previous studies [1-3], the authors have shown that the (EP) of Tajoura’s Experimental Solar Pond (TESP) is undersized and can provide only about 30% of the salt required by a Salt Gradient Solar pond (SGSP). The anticipated size of (EP) was estimated and presented in those studies under different design conditions, including Summer, Autumn and Spring designs, while the winter design was excluded due to the low rates of net evaporation during the winter season.
In addition, the results presented were predicted for the first three years of operation. The daily variations of brine concentration in the (EP) of (TESP) and those based on different designs were predicted and discussed under different scenarios. The quantities of brine provided by the evaporation pond and that required by SGSP were predicted for both cases of surface water flushing (fresh water and sea-water) under the different design conditions as shown in Table 1. This paper investigates the differences between (EP) and (ES) as a source for salt brine generation by evaporation. The effect of (EP) depth on the area ratio and daily variations of salt concentrations for three years of operation is shown. Results show that evaporation can be a reasonable method for salt brine generation. Reducing the depth of (EP) improves the capability of (EP) for brine re-concentration. It also increases the (EP) surface area for the same quantity of saline water used. Therefore, ESs are more powerful than Eps in salt re-concentration.

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