Internal heat transfer of an oil-injected screw compressor using nanofluids

The thermal management of oil-injected screw compressors remains a critical concern for achieving higher energy efficiency, yet conventional cooling oil show limited heat transfer capacity. This study introduces nanofluids as a novel and promising cooling medium in the compression chamber to address this challenge. The phase-field method is employed to simulate single-droplet flow morphology and analyze heat transfer performance, with a focus on the effect of nanoparticle volume fraction, and results are compared against conventional oil. Notably, using a water-based nanofluid with 5% CuO nanoparticles reduces the average gas-phase temperature by 6 K, lowers the maximum wall temperature by 25%, and increases the average wall heat flux by 33% compared to oil. Smaller droplet diameters and higher initial injection velocities further enhance heat transfer. These findings confirm that nanofluids offer a viable and effective route to improve the thermal performance of the compression chamber, with higher nanoparticle volume fractions yielding better heat exchange, thereby providing a practical reference for energy efficiency improvements in oil-injected screw compressors.