A critical review on nanorefrigerants: Boiling, condensation and tribological properties

A major amount of domestic energy consumption is spent on refrigeration and space cooling appliances. The performance of the refrigeration system depends on the thermophysical properties of the refrigerant. Altering the properties by additives such as nanoparticles has proven to be an effective solution to improve the performance of the system. This work swivels around flow boiling, pool boiling, tribological and condensation characteristics of nanorefrigerants in Vapour Compression Refrigeration System (VCRS) and Vapour Absorption Refrigeration System (VARS). An evolutionary timeline of nanorefrigerants is presented. Energy savings on compressor work by addition of nanolubricants is discussed. A sum of thirteen refrigerants and twelve nanoparticles in various combinations were encountered during this review process. CNTs performed better than metallic (Al, Cu, Au, Ag) and ceramic (Al2O3, TiO2, SiO2, ZnO) counterparts. Majority of the work reported enhancement in heat transfer rate and coefficient of performance (COP), however, few studies presented that CuO nanoparticles have shown negative correlation between HF, COP and volume fraction of nanoparticle. The review presents a broad idea on dispersion techniques, stability, properties of boiling and condensation, migration phenomenon of nanoparticles and various novel techniques to improve the performance of the refrigeration systems.