ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Stearic acid-based phase change material with graphene nanoplatelets for evacuated tube solar collector performance assessment

T. Sathish

Department of Mechanical Engineering, Saveetha School of Engineering, SIMATS, Chennai, India

E-mail: sathisht.sse@saveetha.com

Received: 12 January 2026  Accepted: 2 May 2026

Abstract:

The solar thermal collector was the devices that could convert the incoming sun rays into thermal heat energy. The evacuated tube solar collector (ETSC) was a non-concentrated collector type that was used for low-temperature applications. This study investigates the thermal performance enhancements in ETSC using stearic acid-based phase change material (PCM) integrated with graphene nanoplatelets (GNPs). The stearic acid PCM was studied, integrated with different GNP concentrations of about 0, 0.5, 1, 2, and 4 wt% and was analyzed to evaluate their effects on thermal conductivity, specific heat, latent heat, fluid temperature, and collector efficiency. The results showed that the significant improvements in thermal conductivity from 0.23 to 0.67 W/m K and latent heat of fusion from 207.1 to 229.3 kJ/kg with increasing GNP content from 0 to 4 wt%, while specific heat decreased to 2.06 kJ/kg K. The addition of PCM improves the temperature of the fluid to a peak of 86.9 °C, 69.5% of efficiency. Hence, the result shows GNPs improve stearic acid thermal conductivity and energy storage, making it a suitable composite for solar thermal energy systems.

Keywords: Sustainable; Energy; Solar; Evacuated tube; Graphene nanoplatelets

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-05000-3

Chemical Papers 80 (9) 10219–10231 (2026)