Performance evaluation of a domestic vapor compression refrigeration system using periwinkle-shell-derived CaO-rich nano-lubricant in mineral oil

Abstract This study presents a novel approach to improving the performance of domestic vapor compression refrigeration systems (VCRS) through a bio-synthesized nano-lubricant derived from periwinkle shells, a biodegradable waste material. Periwinkle-shell-derived CaO-rich nanoparticles (PSD–CaO nanoparticles) were synthesized via a sustainable method Al 2 (SO 4 ) 3 as a precursor, marking the first application of PSD–CaO nanoparticles in refrigeration. Although bulk composition shows significant SiO 2 inherited from the shell matrix, the active nanomaterial consists of crystalline CaO domains responsible for the observed performance enhancement. Experimental evaluation showed that at 0.1 M concentration, the 0.036 wt.% CaO-rich nanoparticle + mineral oil (M.O.) blend achieved the lowest energy consumption (0.3832 kWh) and power consumption, attributed to enhanced thermal conductivity and reduced friction. Conversely, pure M.O. outperformed nano-lubricant blends at 0.3 M concentration, where nanoparticle agglomeration increased viscosity and reduced lubrication efficiency. At 0.1 M, the 0.06 wt.% CaO-rich nanoparticle + M.O. achieved the lowest pressure ratio, indicating optimal lubrication. Cooling capacity was highest at 0.05 wt.% CaO-rich nanoparticle + M.O. (0.3 M) and 0.08 wt.% CaO-rich nanoparticle + M.O. (0.1 M). The coefficient of performance (COP) peaked at 0.05 wt.% (0.3 M) and 0.024 wt.% (0.1 M), underscoring the importance of nanoparticle dispersion in maximizing thermal efficiency. However, none of the tested configurations met the ISO requirement for pull-down to –12 °C, highlighting limitations in deep cooling capability. The key novelty lies in the eco-friendly synthesis of CaO-rich nanoparticles from waste periwinkle shells, demonstrating a pathway toward waste valorization and energy efficiency. Aligned with Sustainable Development Goals (SDGs) 11.6 and 13.3, this research shows the potential of bio-derived nano-lubricants to enhance VCRS performance, with optimal nanoparticle concentration being central to sustainable refrigeration design.