Experimental studies of radiation transmission in water and numerical simulation of dynamic behavior of a salt-gradient solar pond

Abstract

The development of salt-gradient solar pond modeling has been reviewed and categorized into the six submodels. These models are summarized in tabular form, and the recommendations are provided for continuing areas of investigation to advance salt-gradient solar pond technology toward commercial applications. In order to investigate the effects of water turbidity and salt concentration levels at various water depth on solar radiation penetration. Both outdoor and laboratory studies were conducted. The results indicate that the salt concentration level does not significantly affect the solar penetration through water. However, the clarity of the water, quantified in term s of the turbidity level, plays a critical role in the magnitude of the solar radiation penetration. A best-fit model is presented as a function of turbidity level and water depth. The spectral transmittance of halobacteria and selected chemicals in deionized water at several concentration levels are measured in the laboratory to determine their effect on radiation transmission. The experimental data indicate that the presence of halobacteria significantly affects radiation transmission in salt water. Hydrochloric acid may be the best candidate among the selected chemicals resulting from, its superior radiation transmission. The effect of water turbidity on the thermal performance of a salt-gradient solar pond was studied by incorporating the empirical correlation considering the effect of water clarity on solar radiation penetration into a one-dimensional theoretical model. The analysis was extended to include the solar radiation penetration calculations under non-uniform turbidity distribution. The results indicate that water turbidity plays a critical role in the thermal performance of solar ponds, and high turbidity levels can prevent ponds from storing energy. A one-dimensional transient numerical model has been developed to simulate the dynamic behavior and thermal performance of a salt-gradient solar pond while considering the combined effects of water turbidity, wind-mixing, and double-diffusion. Finite difference methods are used to solve the theoretical model under operating conditions representing a pond located at El Paso, Texas, for the month of August, 1989. The results illustrate the upper and lower convective zones growths and their corresponding effects on thermal performance of the solar pond.