**Abstract**

Since few years, researchers are introduced nanorefrigerant in the recent development of refrigeration systems. This chapter briefly summarizes the behavior of different nanoparticles in vapor compression refrigeration cycle. The nanoparticles' infusion in refrigeration cycle affects the viscous behavior of the refrigerant. It is found that very limited studies have been done on viscosity characteristics of nanolubricants, but few reports states that viscosity increases with nanoparticles additive which improves the tribology of compressor. But inversely, the increment of viscosity promotes to the possible pressure drop in the system which eventually drops the cycle performance. The optimum contribution of nanorefrigerant with high thermal conductivity and low viscosity is the success key of system performance with nanoparticles. However, it is found that the contribution of nanoparticles on the basis of physical phenomena that are affecting the vapor compression cycle is limited in the literature. This chapter aims to make a review on the mechanism of improving vapor compression cycle by using nanorefrigerants.

**Keywords:** nanorefrigerants, nanolubricants, compressor work, coefficient of performance, heat transition
