关键词:

气提效应, 降膜蒸发, 水力学特性, 弹状流

Abstract:

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.

Key words:

气提效应, 降膜蒸发, 水力学特性, 弹状流