Experimentally Investigating the Effect of Basin Water Depth in Passive Pyramid type Solar Still

Abstract

This study is aiming to investigate experimentally the effect of basin water depth on the productivity of passive pyramid type solar still at Indore city of M.P(INDIA) with latitude and longitude (22.7196°,75.8577°). Solar still is very promising solution to address the scarcity of fresh water globally. So, understanding the role of parameter that affects its performance is very important in order to increase its productivity and efficiency, for that we construct a passive pyramid type solar still with square base and tested under varying depth from 2 cm to 10 cm. To evaluate its internal heat transfer and productivity. Temperature profile of ambient air, basin water, basin liner and glass cover also recorded to understand the heat transfer. While operating it with 2cm basin water depth the output distillate is (1020ml). While with 4 cm,6cm,8cm and 10 cm are 860,695,565 and 490ml. Which shows that its productivity is inversely proportional to the basin water depth.Because shallower water depth improves its productivity by faster evaporation. Whereas deeper basin water depth has lower efficiency due to its high thermal inertia. The conclusion of this experiment shows significant statement into the optimal design of the passive pyramid type solar still. This study highlights the importance of basin water depth as a critical parameter of passive solar still, which lay practical recommendation for future research work in solar base desalination system.

Introduction

Access to clean drinking water is critical but challenged by scarcity due to population growth, industrialization, and climate change. Traditional purification methods often require infrastructure and energy that many remote or resource-limited areas lack. Solar desalination, particularly solar stills, offers a simple, low-maintenance, and off-grid solution by using solar energy to evaporate saline or brackish water and condense it into freshwater.

The study focuses on a passive pyramid solar still, which improves on conventional designs by providing a larger condensation area and better solar exposure. A key factor affecting solar still efficiency is the basin water depth: shallower depths evaporate faster but process less water, while deeper depths store more heat but increase thermal inertia, slowing evaporation.

This research experimentally investigates how varying water depths (2 to 10 cm) influence the productivity, thermal behavior, and efficiency of a passive pyramid solar still. Experiments were conducted in Indore, India, recording temperatures, solar radiation, and water quality over five days in January. The study measured internal heat transfer modes—convection, evaporation, and radiation—and found that shallower water depths resulted in higher peak evaporative heat transfer and earlier maximum productivity.

The findings aim to optimize solar still design to enhance freshwater yield sustainably, contributing to global efforts in addressing water scarcity through renewable energy-driven methods suitable for underserved regions.

Conclusion

The square base pyramid type passive solar still is fabricated and experimental analysis is done in the central part of India (Indore) with latitude and longitude (22.7196°,75.8577°) in winter season. Reading of number of parameters and results were obtained for different basin water depth ranging from 2cm to 10cm. On the basis of obtained result following conclusion are drawn. ? The maximum value of basin water temperature obtained in 2cm basin water depth is 58°c. whereas in 10cm basin water depth maximum value of basin water temperature is 46.8°c both values are obtained between 13:00 and 15:00. ? The maximum value of evaporative heat transfer coefficient obtained experimentally in 2cm and 10cm are 23.1 W/m2? and 12.4 W/m2?. ? The maximum value of convective heat transfer coefficient obtained experimentally in 2cm and 10cm are 1.9 W/m2? and 1.78 W/m2?. ? The maximum value of radiative heat transfer coefficient obtained experimentally in 2cm and 10cm are 6.6 W/m2? and 5.97 W/m2?. ? It is observed that the convective and radiative heat transfer coefficient value is very less as compare with evaporative heat transfer coefficient. ? Maximum heat transfer coefficient values are mostly obtained between 13:00 and 15:00. ? The maximum distillate output obtained in 2cm water basin depth is 185ml at 14:00. and maximum distillate output obtained in 10cm water basin depth is 75ml at 15:00-16:00. ? The distillate output obtained at 2cm and 10cm basin water depth are 2.83 kg/m2 and 1.4 kg/m2. So, distillate output become half when increasing the basin water depth by a factor of 5. So, it can be concluded that the effect of basin water depth in the productivity of pyramid type passive solar is in inversely proportional. Which is clearly seen in the result than by increasing the basin water depth from 2cm to 10cm decrease output distillate from 2.83 kg/m2 to 1.4 kg/m2. The value of convective and radiative heat transfer coefficient is very less as compare to evaporative heat transfer coefficient. Maximum distillate output, heat transfer coefficient value are obtained in between 13:00 and 15:00 due to high incoming solar irradiance.

References

[1] B. K. Singh et al., “Performance Analysis of Solar Still by Using Octagonal-Pyramid Shape in the Solar Desalination Techniques,” International Journal of Photoenergy, vol. 2023, 2023, doi: 10.1155/2023/4705193. [2] Y. A. A. A. Malik and O. A. A. Mohammad, “Experimental investigation of the impact of water depth, inlet water temperature, and fins on the productivity of a Pyramid Solar Still,” Journal of Groundwater Science and Engineering, vol. 11, no. 2, pp. 183–190, 2023, doi: 10.26599/JGSE.2023.9280016. [3] F. A. Essa, A. S. Abdullah, and Z. Omara, “Enhancement of pyramid solar distiller performance using thermal storage material,” Journal of Contemporary Technology and Applied Engineering, vol. 2, no. 1, pp. 56–64, Sep. 2023, doi: 10.21608/jctae.2023.233154.1016. [4] A. Muthu Manokar, D. Prince Winston, R. Sathyamurthy, A. E. Kabeel, and A. Rama Prasath, “Experimental investigation on pyramid solar still in passive and active mode,” Heat and Mass Transfer/Waerme- und Stoffuebertragung, vol. 55, no. 4, pp. 1045–1058, Apr. 2019, doi: 10.1007/s00231-018-2483-3. [5] M. R. Safaei, H. R. Goshayeshi, and I. Chaer, “Solar still efficiency enhancement by using graphene oxide/paraffin nano-PCM,” Energies (Basel), vol. 12, no. 10, 2019, doi: 10.3390/en12102002. [6] S. K. S. et al., “Effect of energy storage material on a triangular pyramid solar still operating with constant water depth,” Energy Reports, vol. 8, pp. 652–658, Dec. 2022, doi: 10.1016/j.egyr.2022.10.203. [7] T. R. Mounita, S. N. Shams, M. Shahinuzzaman, G. Hashmi, and M. Hossain, “Design, construction and performance analysis of a four-fold pyramid shaped solar still with different insulation materials and activated carbon,” Desalination Water Treat, vol. 320, Oct. 2024, doi: 10.1016/j.dwt.2024.100888. [8] K. A. Hammoodi, H. A. Dhahad, W. H. Alawee, and Z. M. Omara, “A detailed review of the factors impacting pyramid type solar still performance,” Mar. 01, 2023, Elsevier B.V.doi: 10.1016/j.aej.2022.12.006. [9] E. Ghandourah, H. Panchal, O. Fallatah, H. M. Ahmed, E. B. Moustafa, and A. H. Elsheikh, “Performance enhancement and economic analysis of pyramid solar still with corrugated absorber plate and conventional solar still: A case study,” Case Studies in Thermal Engineering, vol. 35, Jul. 2022, doi: 10.1016/j.csite.2022.101966. [10] A. A. Alshqirate, M. A. Essa, and E. S. I. A. Aziz, “Improved pyramid solar still for solar water desalination – A case study,” International Review of Mechanical Engineering, vol. 14, no. 12, pp. 743–749, Dec. 2020, doi: 10.15866/ireme.v14i12.20051. [11] R. V. Dunkle, “Solar water distillation: the roof type still and multiple effect diffusion still,” in International Development in Heat transfer, ASME, Proceedings of International Heat transfer Conference, University of Colorado: University of Colorado, 1961, pp. 895–902. [12] S. K. Shukla and V. P. S. Sorayan, “Thermal modeling of solar stills: An experimental validation,” Renew Energy, vol. 30, no. 5, pp. 683–699, Apr. 2005, doi: 10.1016/j.renene.2004.03.009. [13] V. V. Tran, “A SIMPLIFIED MATHEMATICAL MODEL FOR PREDICTING THE NOCTURNAL OUTPUT OF A SOLAR STILL,” Pergamon Press. Print~liaGreatBrilain, 1973. [14] J. A. Esfahani, N. Rahbar, and M. Lavvaf, “Utilization of thermoelectric cooling in a portable active solar still - An experimental study on winter days,” Desalination, vol. 269, no. 1–3, pp. 198–205, Mar. 2011, doi: 10.1016/j.desal.2010.10.062. [15] D. B. Hibbert, “Les Kirkup, Bob Frenkel: An Introduction to uncertainty in measurement using the GUM (Guide to the expression of uncertainty in measurement),” Accreditation and Quality Assurance, vol. 12, no. 1, pp. 51–52, Jan. 2007, doi: 10.1007/s00769-006-0221-x. [16] A. S. Nafey, M. Abdelkader, A. Abdelmotalip, and A. A. Mabrouk, “Enhancement of solar still productivity using floating perforated black plate.” [Online]. Available: www.elsevier.com/locate/enconman [17] G. Tiwari, “Effect of Water Depth on Daily Yield of the Still,” 1987. [18] A. Agrawal, R. S. Rana, and P. K. Srivastava, “Heat transfer coefficients and productivity of a single slope single basin solar still in Indian climatic condition: Experimental and theoretical comparison,” Resource-Efficient Technologies, vol. 3, no. 4, pp. 466–482, Dec. 2017, doi: 10.1016/j.reffit.2017.05.003. [19] M. K. Gaur and G. N. Tiwari, “Optimization of number of collectors for integrated PV/T hybrid active solar still,” Appl Energy, vol. 87, no. 5, pp. 1763–1772, 2010, doi: 10.1016/j.apenergy.2009.10.019. [20] H. E. S. Fath and H. M. Hosny, “DESALINATION Thermal performance of a single-sloped basin still with an inherent built-in additional condenser,” 2002. [Online]. Available: www.elsevier.com/locate/desal [21] E. Sartorit, “SOLAR STILL VERSUS SOLAR EVAPORATOR: A COMPARATIVE STUDY BETWEEN THEIR THERMAL BEHAVIORS,” 1996.

Copyright

Copyright © 2025 Anuj Shringi, Jaideep Sharma, Priyanka Malviya. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.