The theory of operation is the same as that of the ejector. It is better suited to evaporation and distillation processes in which it is economically advantageous to recover the energy from the vapor generated by evaporation. This vapor is heated slightly by recompression through a thermocompressor before passing on its calorific energy to the fluid to be evaporated. Often, optimum efficiency is obtained with a very low compression factor (between 1.3 and 1.6).