﻿ 东南大学学报(自然科学版)

(东南大学能源与环境学院, 南京 210096)

Effects of filler surface conditions on falling-film plate wettability using LiCl-H2O
Lü Yue，Yin Yonggao
(School of Energy and Environment, Southeast University, Nanjing 210096, China)(Engineering Research Center for Building Energy Environment and Equipments, Ministry of Education, Southeast University, Nanjing 210096, China)

To improve the wettability of the filler surface in the liquid desiccant air conditioning system, the effects of tilt angles contact angles and surface morphologies on the filler surface on wettability and the critical amount of spray using LiCl-H2O were studied by computational fluid dynamics(CFD)simulation. The results show that the smaller the surface tilt angle, the smaller the fluctuation of the solution film surface and the better the wettability. The smaller the contact angle of the filler surface, the better the wettability the smaller the critical amount of spray required to reach the full-film flow. The critical amount of spray increases significantly when the contact angle of the filler surface changes from 40° to 60°. The wettability of the wavy filler surface is significantly improved compared with that of the flat filler surface for a small amount of spray. When the amount of spray is 0.288 m3/(m·h), the wetting ratio of the wavy filler surface with 5 mm wave height is more than 50% larger than that of the flat surface. Although the wetting ratio increases with the increase of the wave height, the growth of the wetting ratio is only about 5%. In addition, because the stability of the liquid film on the wavy surface is poor, the critical amount of spray required for the wavy surface is larger than that of the flat surface.

1 计算模型1.1 物理模型

1.2 数学模型及相关参数

αLG=1(1)

(∂αG)/(∂t)+v·=0(2)

(∂(ρv))/(∂t)+▽(ρvv)=-p+

[μ(v+vτ)]+ρg+Fvol(3)

(∂ρ)/(∂t)+(ρv)=0(4)

ρ=αLρLGρG(5)

μ=αLμLGρG(6)

Fvol=∑i<jσijjρjκj▽αjiρiκi▽αi)/(1/2(ρij))(7)

WR=(Aw)/(Ab)(8)

S=(QL)/w×3 600(9)

2 网格独立性验证

3 模拟结果及分析3.1 填料表面倾斜角对润湿性的影响

3.2 填料表面接触角对润湿性的影响

3.3 填料表面形态对润湿性的影响

4 结论

1)倾斜角越小,润湿性能越好,保证满膜流动所需的临界喷淋量越小.因此实际运行中填料表面的倾斜角越小越好.

2)接触角越小,润湿性能越好,保证满膜流动所需的临界喷淋量越小.另外,当接触角从40°变化到60°时临界喷淋量的增长量最大.因此处理填料表面其接触角应小于40°为好.

3)在喷淋量较小时,波形填料表面较平面具有更大的润湿性优势.但保证满膜流动时波形填料表面所需的临界喷淋量比平面大.因此若希望在较小的喷淋量条件下有较大的润湿面积,则填料表面选择波状比较好.若需要满膜流动,则平面填料表面所需的最小喷淋量较小.实际过程中还应按照需求选择合适形态的填料表面.