Nanoscale boiling and bubble dynamics of R152a/R1234ze(E) blends: Insights from molecular dynamics simulations

Abstract

Phase change characteristics of refrigerant blends is essential due to their wide applications and environmental relevance. This work investigates nanoscale boiling in R152a/R1234ze(E) blends using non-equilibrium molecular dynamics (NEMD) simulations under controlled heating (80–200 K/ns). Five compositions (0 %, 33 %, 50 %, 67 %, and 100 % R152a) are analyzed in a three-phase domain comprising liquid and vapor over a platinum wall with linearly increasing temperature to induce necessary phase change. Key characteristics—atomic kinetics, net evaporation, wall heat flux, bubble nucleation/growth, and near-wall temperature—are examined across blend ratios and heating conditions. Increasing R152a enhances boiling performance with a significant change in boiling mode. Significant enhancement in net evaporation number, bubble volume growth rate and time-average heat flux is noticed with the increase in R152a for all heating rates. However, blend of 67 % R152a demonstrates thermal performance comparable to pure R152a at low as well as high heating rates, but lags at moderate rates. Interfacial analysis shows the interfacial thermal resistance of R1234ze(E) is approximately 34 % lower than that of R152a although the bulk thermal resistance of R1234ze(E) is higher. Moreover, increase in R152a in the refrigerant blend enhanced its interfacial thermal resistance. This contrast enables optimal heat transfer in mixed compositions. Specifically, the 67 % R152a blend benefits from favorable molecular distribution, balancing interfacial and bulk transport properties for improved phase change behavior. These findings provide insights into tuning refrigerant blends for efficient heat transfer in nanoscale boiling systems.