Experimental study of falling film evaporation in large scale rectangular channel

• This paper studies the falling film evaporation in large scale rectangular channel experimentally.
• The effects of air flow rate, film temperature and film flow rate on falling film evaporation are analyzed.
• Increasing the air flow rate is considered as an efficient method to enhance the evaporation rate.
• A correlation including the wave effect for falling film evaporation is derived based on heat and mass transfer analogy.

The falling film evaporation in a large scale rectangular channel is experimentally studied in this paper for the design and improvement of passive containment cooling system. The evaporation mass transfer coefficient hD is obtained by the evaporation rate and vapor partial pressure difference of film surface and air bulk. The experimental results indicate that increasing of air flow rate appears to enhance hD, while the film temperature and film flow rate have little effect on hD. Since the wave effect on evaporation is noticed in experiment, the evaporation mass transfer correlation including the wave effect is developed on the basis of heat and mass transfer analogy and experimental data.