|
The research was conducted in department of rural engineering at faculty of agricultural engineering-university of Damascus during the years 2020-2021 with aim of designing and evaluating effectiveness of a single-effect diffusion vertical solar still equipped with a flat solar collector with a design productivity of 5 [L/m2.day] and studying the effect of some factors on the effectiveness of the still: (ambient temperature, solar radiation, speed of wind, air humidity, temperature of flat solar collector and temperature of single-effect diffusive vertical solar still). The single-effect diffusion vertical solar still was equipped with an additional heat exchanger within the condenser tank with external fins to study its effect on temperature of condensation. The measured quantity of distilled water was compared with the theoretical values calculated in different periods of the years 2020-2021, and some of the chemical and bacterial specifications of the water were compared (PH, electrical conductivity (EC), percentage of total salts (TDS), concentration of some elements such as calcium (Ca), sodium (Na), and the General bacterial count) before and after desalination with the permissible limit within the Syrian standard specification for drinking water (45/2007) in order to determine the suitability of the water for consumption. The results of the theoretical study showed that the size of a single-effect diffusion vertical solar still necessary to provide a quantity of water of 5 [L/m2.day] was 0.25 [m3] and area of a flat solar collector was 0.64 [m2]. The highest value for quantity of distilled water was recorded during July with an average 4.8 [L/m2.day] which was equivalent to 96% of the design value, and its average productivity during June and August reached 4.2 [L/m2.day] and this was equivalent to 84% of the design value. As the highest average efficiency of a single diffusion vertical solar still ranged between 81.6 and 93.8% during June, July and August. Pearson correlation coefficient (r) between amount of distilled water calculated by design model of a single-effect diffusion vertical solar still and amount of distilled water measured experimentally was 0.99, while Nash-Sutcliffe efficiency factor (EF) of the model was 0.95, and this indicated a great convergence between the amount of water calculated theoretically and the amount of water measured experimentally, as this indicated that the simulation of the theoretical design model with the experimental model was highly accurate, so the size of the single-effect diffusion vertical solar still designed for this research was considered an appropriate means to obtain the desired amount of water. The results of the study showed that the area of the additional heat exchanger for the condenser amounted to 0.04 [m2]. The additional heat exchanger contributed to maintaining the condensation temperature within the condenser tank at an average of 30 [C⁰], which was similar to the theoretical design value. Therefore, the additional heat exchanger for the condenser was considered an appropriate means of improving Performance of a single-effect diffusion vertical solar still. The average pH of water samples after desalination was 6.93, and the average EC value of water after desalination was 169.6 [μS/Cm]. The percentage of total salt reduction in water samples after desalination ranged between 91.4 and 94.3%. Additionally, the average calcium content in water after desalination was 11.3 [ppm]. The average hardness value of water after desalination was 120 [ppm], while the average sodium content was 6.2 [ppm]. The results indicated that water specifications after desalination using a single-effect diffusion vertical solar still met the permissible limits set by the Syrian standard for drinking water (45/2007). Therefore, the water was suitable for use in terms of the studied characteristics. The correlation coefficient between the productivity of the single-effect diffusive vertical solar still and the intensity of solar radiation reached 0.91. This indicates a strong correlation, as increasing productivity was linked to increasing solar radiation. Therefore, the flat solar still that was used in the research was a good way to secure the thermal energy necessary for distillation to occur.
|
|
Keywords: Single-Effect Diffusion Vertical Solar Still, Flat Panel Solar Collector, Additional Heat Exchanger, Solar Radiation, Standard Specification for Drinking Water.
.
|
