Heat transfer coefficients and yield analysis of a double-slope solar still hybrid with rubber scrapers: an experimental and theoretical study

In this study, a new double-slope solar still hybrid with rubber scrapers (DSSSHS) and a double-slope solar still (DSSS) were designed, manufactured and tested. The proposed design of DSSSHS makes use of the advantages of using a small slope of the condensing cover of the still that allows higher solar radiation to enter into the still. Disadvantages resulting from using the small slope are overcome by using the rubber scrapers. No researcher has yet used the scrapers in solar still. Experimental measurements and results were used to calculate the theoretical values of convective and evaporative heat transfer coefficients, in addition to the theoretical values of the yields. Results of the two models were compared to evaluate the advantages of using rubber scrapers in the new model. Using rubber scrapers in DSSSHS model enhanced the total internal heat transfer coefficient (h1) as well as the productivity. The maximum recorded value of the total internal heat transfer coefficient for the DSSSHS is found as 38.754 W/m2 °C and the daily yield as 4.24 L/m2 day with productivity improvement of 63%, for the case when the inclination angle of the glass cover is quite small (about 3.0°)

Hourly yield prediction of a double-slope solar still hybrid with rubber scrapers in low-latitude areas based on the particle swarm optimization technique

Several studies have attempted to improve the productivity of solar stills and build expressive models for yield prediction. However, most of these models do not consider the amount of condensed water that falls from the condensing cover towards the solar still basin, especially in the case of small-slope covers. This oversight can significantly affect the accuracy of these models. In this study, we developed a fairly simple method to estimate the amount of distilled water produced every hour from the double-slope solar still hybrid with rubber scrapers (DSSSHS) in low-latitude areas. The proposed model is based on the determination of the best values for the unknown constant (C) and the exponent (n) for the Nusselt number expression used to formulate the equation for the estimation of the hourly yield of a solar still (HYSS). This was achieved by solving an optimization problem using the particle swarm optimization (PSO) algorithm in which the optimal yields were determined by estimating the optimal values of the unknown C and nparameters. This technique, which is used for the first time in this study to build a yield prediction model, avoided the conventional trial-and-error approach to calculating unknown coefficients in a proposed model. Furthermore, the use of rubber scrapers to collect the condensed water that accumulates on the inner surfaces of the condensing cover enhanced the accuracy of the measurement of solar still experimental yields, which consequently improved the accuracy of the model. The proposed model was validated against the experimental data collected in this study. The results showed that the built model was able to accurately estimate the HYSS values

Productivity enhancement and modelling of a new double-slope solar still with rubber scrapers in low latitude areas

Potable water is vital for our existence. Despite the fact that more than three-quarters of the earth is covered by water, only 0.014% of it is potable. Therefore, sustainable, safe, cheap, and environment-friendly techniques must be developed to produce potable water from salty water. Solar distillation is a promising method that is safe for the environment and uses only sustainable energy for its operation. The productivity of a solar still becomes a major challenge and therefore necessitates many modifications in design and operation to increase its amount. A solar still with high productivity can be achieved when the condensing cover slope is the same as the latitude angle of the solar still location. The main problem that occurs in the solar still is the fall down of water condensate from the glass cover due to gravity. In this study, a new double slope solar still hybrid with rubber scrapers (DSSSHS) and a double slope solar still (DSSS) were designed with a 3.0° slope condensing cover. The main objective of the study is to obtain the maximum yield of distilled water by using the new DSSSHS during daytime. The proposed design of the new solar still utilizes the advantage of using a condensing cover with a small slope angle to allow the entry of the maximum amount of solar radiation into the still. The disadvantages caused by the condensing cover with a small slope were overcome by using rubber scrapers. In this research, two (2) double slope solar stills one with rubber scrapers and the other without rubber scrapers were designed and fabricated. In the two solar stills, the condensing cover was placed at 3.0° which is equal to the latitude angle of the experiment location. Several experiments were conducted using the newly designed solar stills under different climatic conditions. The productivities of the two new solar stills were measured experimentally. For comparison, the saline water used and the distilled water produced from the DSSSHS were characterized. Experimental results obtained from the DSSSHS were used to construct the prediction models using the linear regression method and particle swarm optimization (PSO) algorithm with the aid of MATLAB software. The prediction models are the regression model, Particle Swarm Optimization Algorithm-Hourly Yield of Solar Still (PSO-HYSS) model, and extended PSO-HYSS model. In terms of the orientation of the still, there is an increase in daily productivity which varies from 12.3% to 13.2% when using east-west orientation compared with the north-south orientation. Moreover, the experimental results showed that the daily productivity of the DSSSHS (4.24 L/m2.day) is higher than that of DSSS (2.6 L/m2.day) under the same design, environmental and operational conditions. This result signifies that the use of rubber scrapers had enhanced the productivity of the still by 63%. The results showed that the productivity of DSSSHS per unit solar radiation is directly proportional to the number of scraper movements per hour (NSM). The predicted yields of the three prediction models were compared with their corresponding experimental yields to evaluate their accuracy. The results showed that the extended PSO-HYSS model is the most accurate, followed by the PSO-HYSS model and then the regression model

Numerical analysis for solar panel subjected to an external force to overcome adhesive force in desert areas

The dust accumulation is an undesirable phenomenon in a solar plant environment. The dust removing procedures were using traditional techniques which are led to more loss in power especially in desert areas. Additionally, most of the cleaning techniques are designed according to the concept of vanquishing the adhesive force of dust particles by adding a harmonic excitation force. This force may produce damage to the solar panel. Therefore, the main objective of the current study is to simulate a traditional solar panel model BSP32-10 with ANSYS software throw an additional external force (2, 4, 6, 10, and 15 Newton) throws six mode shapes and verified experimentally. Deformation values of solar panel surface increase with an increase in excitation force, and not exceed the natural frequency deformation, with average values from 0.07 to 1.5 mm, while 94% of these results are close to experimental work during verification action. Middle position of the solar panel for excitation force on the solar panel in the dust removal concept is the best position