A three-dimensional model was built up to simulate the process of the refrigerant R410A falling film evaporation outside a horizontal tube. The influence of spray density

heat flux and the horizontal distance from the spray hole to the tube axle on falling film flow and the heat transfer was investigated. The results show that the liquid film thickness and local heat transfer coefficient decrease and tend to be stable along circumferential direction of the tube. The film thickness increases and the local heat transfer coefficient decreases near the bottom of the tube due to the local liquid accumulation. The total heat transfer coefficient decreases with the increase of heat flux and significantly increased with the increase of spray density when the spry density is low. After the liquid film Reynolds number reaches 2000

the total heat transfer coefficient increases slowly and tends to be stable with the increase of spray density. The increase of heat flux will also lead to the rise of the total heat transfer coefficient. As the eccentricity of the cloth liquid increases

the total heat transfer coefficient will rise slightly and tend to be stable

and then the total heat transfer coefficient will drop sharply due to local “dry” and liquid film accumulation areas. With the increase of the spray density

the critical point of the sharp decline in the total heat transfer coefficient will gradually shift to long horizontal distance from the spray hole to the tube axle.