Experimental study of a solar still with heat pipe solar collector and selected phase change material for wastewater treatment and simultaneous hot water generation


Sharma M., Tyagi V., Chopra K., Kothari R., Saxena A., SARI A., ...More

Separation and Purification Technology, vol.393, 2026 (SCI-Expanded, Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 393
  • Publication Date: 2026
  • Doi Number: 10.1016/j.seppur.2026.137160
  • Journal Name: Separation and Purification Technology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC
  • Keywords: Energy efficiency, Evacuated tube collector, Exergy efficiency, Palmitic acid, Solar still, Wastewater
  • Karadeniz Technical University Affiliated: Yes

Abstract

In this study, a hybrid system comprising a single basin solar still and an evacuated tube collector has been designed, where palmitic acid was used as a phase change material filled inside the evacuated tubes. The system was run at a 5 LPH flow rate and two wastewater depths (2.8 cm and 3.2 cm). At a larger wastewater mass, the highest productivity of 5700 mL/m2.d was achieved, which was 196.875% higher than the traditional system. Based on distillate output and hot water productivity, the energy and exergy efficiency were computed. The highest value of energy efficiency was 34.53% in terms of hot water productivity and 33.7% in terms of distillate output at 3.2 cm wastewater mass. When analysed for hot water productivity, the highest exergy efficiency came out to be 22.39%, and for distillate output, it was 2.86% at 3.2 cm wastewater mass. The use of palmitic acid enhances the extension period of the system by 2–4 h. This designed system can also produce hot water that may be used for a variety of domestic tasks for consecutively 8.5 h and 11.5 h at wastewater masses of 2.8 cm and 3.2 cm, respectively. The hybrid system effectively removes total dissolved solids, chemical oxygen demand, and biological oxygen demand with removal efficiencies of 90.97%, 94.58%, and 97.03%, respectively.