분자동역학 해석을 이용한 다양한 응축온도에서 R448A와 R449A의 상변화 및 열물성 평가

Abstract

Molecular dynamics simulations are performed to evaluate phase transition phenomena, liquid density, shear viscosity, and the isobaric heat capacity of low GWP refrigerants R448A and R449A. Increasing the condensing temperature from 273.15 K to 298.15 K leads to increase in the phase change duration of R448A and R449A. Moreover, the liquid density decreases to 11.24% for R448A, and 12.34% for R449A with the an increase in temperature from 273.15 K to 308.15 K. The particles’ snapshots reveal that vapor molecules undergo a rapid phase transition, to the subcooled liquid at a certain condensing time period. Subcritical clusters of R448A and R449A refrigerants’ molecules are formed in the initial part of the simulations, which then aggregate to produce the critical condensate nucleus over time. The liquid density, shear viscosity, and isobaric heat capacity of the two refrigerants predicted by the present MD simulations agree well with data of REFPROP.