Application of CuO Nanoparticles as Biodegradable Lubricant Additive for Domestic Refrigerator Compressors—An Experimental Investigation

Abstract

The application of nano-sized particles is increasing in refrigeration lubricants due to their considerable rise in thermal and heat transfer characteristics for improvement in coefficient of performance (COP) of the refrigeration system. The present study investigates the tribological behaviour of nano-CuO-based biodegradable refrigeration oil using four-ball tribometer. First, the pentaerythritol ester biodegradable refrigeration oil (PE) is blended with synthetic refrigeration oil (ISO 68 grade-POE oil) in the fraction of 50% by volume. Then the pentaerythritol ester-based biodegradable refrigeration oil blend (PE50) is mixed with CuO nanoparticles in the concentration of 0.1% to 0.3% (w:w) to prepare CuO nano-biodegradable refrigeration oil. The friction and wear experiments were conducted using the ASTM D 4172. The wear scar of the ball surfaces was analysed using a scanning electron microscope (SEM). The results show that CuO nano-based biodegradable refrigeration oil has good lubricity property. The tribological behaviour of nano-CuO 0.3% biodegradable refrigeration oil shows superior friction and wear reduction behaviour when compared other than nano-blends with PE50 and (ISO 68 grade-POE oil) synthetic refrigeration oil.