# Equation for enegy loss from evaporation/sublimation in vacuum?

Imagine you have a solid that you are rapidly heating inside a vacuum chamber with some kind of thermal heater or a laser such that the material begins to evaporate or sublimate. Obviously radiative losses scale as $$T^4$$ but then energy is also lost via evaporation or sublimation. Is there an equation that allows for the energy lost by evaporation to be accounted for, given a temperature $$T$$ and perhaps the enthalpy of vaporization $$\Delta H$$?

In addition, how is this loss accounted for in the heat equation, is there an extra term to include alongside conduction and radiation?

• The outgoing heat flux is the enthalpy of vaporization at that particular temperature. Commented Nov 24, 2021 at 16:21

• I know about open systems, but I am trying to figure out if this energy loss can be accounted for easily, given that I want to put this into a energy balance equation ($dU/dt$) then convert this into a weak form. Currently I have a mass term, $dm = \Gamma \Delta H M$ where $\Gamma$ is the mass evaporation rate and M is the molar mass of the liquid. Would this account for it? Commented Nov 25, 2021 at 11:07