Molecular dynamics study of the thermal behavior of ammonia refrigerant in the presence of copper nanoparticles at different volume ratios and initial temperatures

Generally, the addition of nanoparticles to a fluid significantly increases the thermal conductivity of structures. In the present study, the effect of nanoparticle volume ratio and initial temperature on ammonia/copper nano-refrigerant's thermal behavior in an external electric field in an aluminum nanochannel was studied by molecular dynamics simulations. To study the thermal behavior of the structures, quantities such as particle phase-changed rates (condensation process), phase change duration, and thermal conductivity were investigated. Results show that with the addition of 5% copper to the base fluid, the rate of the phase-changed particles increases from 53 to 71% during 2.40 ns. Also, increasing the volume ratio of nanoparticles up to 5% leads to an increase in thermal conductivity from 0.76 to 0.86 W/mK. On the other hand, increasing the initial temperature up to 350 K reduces the phase-changed particles' rate from 53 to 49% during 2.9 ns. The initial temperature increases from 300 to 350 K, and the thermal conductivity decreases from 0.76 to 0.73 W/mK. The results of this simulation are expected to improve the thermal performance of different nano-refrigerants.