Falling film evaporator is characterized by short contact time between the process fluid and the heated surface

high heat transfer coefficients

minimal pressure drop

minimal static head and small process fluid holdup

which make it applicable to small temperature difference heat transfer.However

a circulating pump is a must-be equipment to pump the fluid to the top of the evaporator.In this paper

a new falling film evaporator combined with vapor-lift effect was proposed to realize no pump circulation

which in turn made the system more simple

compact and reliable.A mathematical model based on the slug-flow transportation theory was proposed to analyze the hydrodynamic characteristics of the transportation unit.The results indicated that the proposed falling film evaporator combined with vapor-lift effect could realize stable transportation by vapor slug when the vapor fraction was between 0.3% and 5%.For each liquid flow rate

there was a maximum pumping height and minimum suction height.