Experimental investigation of vertical solar still with rotating discs

ABSTRACT

Solar desalination is a viable solution to provide drinkable water to remote areas using free energy, basic technologies, and a healthy environment. The challenge of low daily productivity inspires the researchers to find different approaches to increase the thermal performance of the distillation methods with minimized cost. This paper proposed a new distillation concept using solar stills. An innovative designed vertical distiller with two rotating discs was investigated. Besides, the performance of modified single-stage vertical distiller (MSSVD) and modified double stage vertical distiller (MDSVD) were studied and compared with that of the conventional tilted distiller (CTD) and conventional vertical distiller (CVD). Reaching the optimal depth of basin water and augmenting the evaporation and condensation rates of the vertical distiller were targeted. Moreover, different rotational speeds (from 0.125 rpm to 2.5 rpm) were investigated to indicate the optimum disc speed that provide the highest productivity. Experimental results indicated that the proposed vertical solar still provided higher freshwater productivity than the CTD. In addition, using rotating discs significantly improved the distillers’ yield. Also, the best distiller performance was achieved at 1.5 rpm. Moreover, the daily freshwater output was 2300 mL/m².day for CTD, 2730 mL/m².day for CVD, 10350 mL/m².day for MSSVD, and 16500 mL/m².day for MDSVD. So, the yield of MSSVD and MDSVD was improved by 350% and 617.4%, respectively over that of CTD. The maximum thermal efficiency for MSSVD and MDSVD was 48.4% and 77.2%, respectively. Finally, the average distillate cost was 0.027, 0.051, 0.018, and 0.019 $/L for CTD, CVD, MSSVD, and MDSVD, respectively.

KEYWORDS:

• Vertical solar still
• Disc distiller
• Rotational speed
• Desalination
• Saline water

Abbreviations

CTD Conventional tilted distiller

CVD Conventional vertical distiller

MDSVD Modified Double Stage Vertical Distiller

MSSVD Modified Single Stage Vertical Distiller

Declarations

Ethical Approval

Not applicable

Funding

We did not receive any funding for this work.

Competing interests

No competing interests

Availability of data and materials

Not applicable

Research highlights

• Vertical distiller performance was investigated with and without rotating discs.

• The impact of disc speed variations (starting from 0.125 to 2.5 rpm) was studied.

• The water depth (5 cm) was tested.

• The MDSVD yield was enhanced by 617.4% over CTD at 1.5 rpm and 5 cm water depth.

• The best efficacy was 77.2% at 1.5 rpm and 5 cm water depth for MDSVD.

Nomenclature

English Symbols

Table

Greek symbols

η Efficiency

Additional information

Notes on contributors

Fadl Abdelmonem Essa

Dr. Fadl Abdelmonem Essa was born in Kafrelsheikh, Egypt, on May 15^th, 1988. He received a bachelor’s degree in Mechanical Engineering from Kafrelsheikh University in 2010. Then, he received his master's degree on June 2^nd, 2014, from Tanta University, Egypt. In 2013, he spent one month at People’s Friendship University of Russia, Moscow, Russia. Moreover, he got his Ph.D. in Mechanical Engineering from School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan, China on June 20^th, 2018. To date, he works as an assistant professor of mechanical engineering, Faculty of Engineering at Kafrelsheikh University in Egypt. The main research fields are water desalination, solar energy applications, sustainable energy development, and material and nanoparticles characterization. He won numerous scientific awards such as the State Encouragement Award (2020) in Engineering Science, Egypt, Chinese Government Outstanding International Student Scholarship Award from Chinese Scholarship Council, and others. Besides, he is the Deputy Director of Quality Assurance Unit, Faculty of Engineering, Kafrelsheikh University, Kafrelsheikh, Egypt, from November 6^th, 2018, till now. He published more than 80 SCI journal papers and around 15 conference papers. He was asked to review papers for numerous international journals like Journal of Cleaner Production, Desalination, Energy, Applied Thermal Engineering, Solar Energy, Wear, and so many others.

Fawzy Shaban Abou-Taleb

The associate professor Abou-Taleb was born in Dakahliya, Egypt, on November 5^th, 1957. He received his B. Sc. in Mechanical Power Engineering from Minoufiya University in 1980. Then, he received his master's degree in March 1986, from Minoufiya University, Egypt. Also, he got his Ph.D. in Mechanical Power Engineering from Moscow Power Institute on Feb. 1994. Now, he occupies the Head of Mechanical Engineering Department, Faculty of Engineering, Kafrelsheikh University in Egypt.

Mohamed Ragab Diab

Mohamed Ragab Diab was born in Kafrelsheikh, Egypt, in 1994. He received the B.Sc. degree in mechanical engineering from Kafrelsheikh university, Kafrelsheikh, Egypt, in 2017. He is currently pursuing an M.Sc. degree at Kafrelsheikh University, Egypt, Department of mechanical engineering. He is currently working as a teaching assistant with the faculty of engineering, Kafrelsheikh University, Egypt. His research interests include renewable energy, desalination, and mechanical engineering.