Demystifying interface accommodation coefficients in liquid-vapor phase change devices: role of surface charge, contaminant, and confinement

Liquid-vapor phase change is essential in power generation, heating and cooling, thermal desalination, and membrane distillation. With the advancements enabled by micro/nanoengineering of phase change devices, the interfacial transport resistance becomes increasingly important, dictating the ultimate performance limit. However, fundamental understanding of the interfacial process remains elusive, particularly regarding the interface accommodation coefficients (IACs), which quantify the probability of evaporation and condensation events at the molecular level. Characterizing IACs has been a long-standing challenge, primarily due to the lack of experimental designs sensitive enough to molecule-interface interactions and capable of distinguishing various contributing factors.The DIAL project aims to demystify the complexities surrounding IACs arising from three key factors – surface charges, interface contamination, and nanoconfinement. Here, we decouple these largely overlooked or insufficiently studied factors by designing a series of targeted experiments, leveraging IR and confocal Raman microscopy for combined thermometry and chemical analysis. With evaporating droplets in vacuum, we establish the baseline for IACs first on pure and then on charged and contaminated fluids. Meanwhile, to investigate the effect associated with phase change devices, we characterize contaminant migration and the corresponding impact on evaporation from membranes with microscale pores and at the same time, build a multiscale model relating IACs to device performance. Finally, with evaporation from sparsely spaced nanotube arrays, we examine the nanoconfinement effect on IACs, overcoming the optical diffraction limit.By isolating or minimizing specific effects in each configuration, our experiments collectively advance the fundamental understanding of liquid-vapor interfacial transport while offering practical design insights for all interface-sensitive energy and water systems.