Using molecular dynamics approach to investigate the effect of copper nanoparticles on the thermal behavior of the ammonia/copper coolant by focusing on aggregation time

Abstract

Nanofluids, fluids containing nanometer-sized particles, have significant properties which make them useful in devices and systems. They boost thermal conductivity and heat transfer better than base fluid. This research studied the atomic behavior, and thermal behavior of simulated ammonia -copper nanofluid using molecular dynamics (MD) simulation method. The effect of increasing Cu nanoparticles' volume fraction (phi) (1-10 %) on the atomic behavior and thermal behavior of nanofluids was studied. The atomic behavior of simulated structure was studied with velocity and temperature profiles. The maximum values of velocity and temperature were 0.00086 angstrom/ps and 240 K, respectively. To study the thermal behavior of simulated structure, heat flux and the aggregation time (AT) of nanoparticles (NPs) were studied. Numerically, the heat flux (HF) and the aggregation time of Ammonia -Cu nanofluid converged to 1411 W/m2 and 3.96 ns, respectively. The study showed that the maximum velocity and temperature decreased by increasing phi. Moreover, by increasing the phi to 5 %, the heat flux and aggregation time increase to 1553 W/m2 and 4.05 ns. By more increase of NPs up to 10 %, the heat flux and AT of samples decrease. By increasing NPs by 10 % in the base fluid, the aggregation process of NPs occurred in a shorter time. It reduces the thermal efficiency of simulated samples.