Condensation evaporator is multi-layer plate-fin. The hot and cold fluid in each channel exchanges heat well through the plate-fin and baffle.The condensation evaporator is generally located between the upper and lower towers, in which the nitrogen rising from the lower tower is condensed and the liquid nitrogen returning from the upper tower is evaporated.This process can be realized mainly based on the difference of boiling points of high-pressure nitrogen and low-pressure nitrogen and the existence of a certain temperature difference.Condensate evaporators are used in cascade refrigerators.