Performance investigation of vapor compression refrigeration system using novel amine treated graphene quantum dots based nanosuspension

In this work, the performance parameters of the vapor compression refrigeration system are investigated using novel amine treated graphene quantum dots-(AGQD) based nanosuspension. The experimentation is carried out in two phases. In the first phase, the synthesis of AGQD based nanosuspension along with the evaluation of thermophysical properties such as thermal conductivity, specific heat, density and viscosity is carried out. The AGQD nanosuspension is synthesized by mixing it in polyalkylene glycol (PAG) refrigeration oil with a concentration of 100 ppm, 200 ppm, and 500 ppm. The experimental result showed that the use of AGQD nanoparticles significantly enhances the thermal conductivity of the PAG lubricant oil with corresponding decrease in specific heat along with minimal enhancement in density and viscosity. The results are also validated with the corresponding mathematical models. In the second phase of the experimentation, the performance parameters of vapor compression refrigeration system are investigated by incorporating synthesized nanosuspension. The experiment is carried out using varying masses of 160 g, 180 g, and 200 g of R134a refrigerant. Each mass of refrigerant is investigated with all three different AGQD-PAG based nanosuspension in the refrigeration system. The performance parameters such as COP, power consumption, mass flow rate, compressor discharge pressure, vapor quality, evaporator pressure, pressure drop and pull down time of vapor compression refrigeration system are experimentally investigated and validated with mathematical models. The highest COP of 2.76 along with 27.36 % of lower power consumption is noted by using 200 g of R134 refrigerant with 500 ppm of AGQD-PAG based nanosuspension.