New paper: are evaporation and condensation coefficients really equal?

Unmeelan’s second paper analyzing International Space Station experiments is now out in Nanoscale and Microscale Thermophysical Engineering: Investigating the Inequality of Phase Change Coefficients Using ISS Experimental Data.

Kinetic models of phase change describe how readily molecules cross a liquid–vapor interface using accommodation coefficients. Because they are hard to measure, it is almost universal practice to assume the evaporation and condensation coefficients are equal. Using data from the Constrained Vapor Bubble experiment, where microgravity strips away buoyancy and makes interfacial effects easier to see, this paper tests that assumption directly and shows that the choice has a real effect on predicted heat and mass transfer.

This paper builds on our 2023 paper showing that the same interfaces are not isothermal. Together, they make a strong case for revisiting the simplifications built into standard phase change models. More on this line of work is on our ISS research page.