析湿工况下翅片管式换热器表面粉尘沉积过程的数值模型

doi:10.11949/0438-1157.20191435

摘要/Abstract

摘要：

空调器采用翅片管式换热器作为蒸发器，在制冷工况下换热器表面发生析湿及粉尘沉积，导致性能衰减。建立湿翅片表面粉尘颗粒物沉积过程的数学模型，模拟冷凝水捕集颗粒物以及湿积灰层黏附颗粒物的过程。被冷凝水捕集的颗粒物数量等于运动轨迹与水表面轮廓会出现相交的入射颗粒物的数量；后续的入射颗粒物与湿积灰层碰撞时，部分入射颗粒物会发生沉积且部分被碰撞的已沉积湿颗粒物会发生移除，这两部分的颗粒物数量相减即为被湿积灰层黏附的颗粒物数量。模拟与实验结果的对比表明，预测的湿积灰层形状与实验照片的吻合度较好，预测的单位面积颗粒物沉积质量与91%的实验数据之间的误差在±20%之间，平均误差为11.8%。

关键词: 翅片管式换热器, 颗粒物沉积, 析湿工况, 数值模型

Abstract:

The air conditioner uses a finned tube heat exchanger as the evaporator. Under the cooling condition, the dehumidification and dust deposition on the surface of the heat exchanger cause performance degradation. The purpose of this study is to develop a wet particle deposition model for predicting the particle-capturing by condensate water and the particle adhesion on wet particulate layer. The number of particles captured by condensate water is the number of incident particles whose trajectories intersect with the water surface. During the impact between subsequent incident particles and wet particulate layer, some incident particles may stick on the wet particulate layer while some deposited wet particles may remove from it, and the number of particles adhered on wet particulate layer equals to the number of stuck particles minus the number of removed particles. The validation results show that, the predicted shape of wet particulate layer agrees well with the experimental images, and the predicted mass of deposited particles agrees with 91% of the experimental data within a deviation of ±20% and the mean deviation is 11.8%.

Key words: fin-and-tube heat exchanger, particle deposition, wet condition, numerical model

中图分类号:

TB657.5

詹飞龙, 丁国良, 庄大伟, 张浩, 武滔, 叶向阳. 析湿工况下翅片管式换热器表面粉尘沉积过程的数值模型[J]. 化工学报, 2020, 71(5): 1986-1994.

Feilong ZHAN, Guoliang DING, Dawei ZHUANG, Hao ZHANG, Tao WU, Xiangyang YE. Numerical model of dust particle deposition process on surface of fin-and-tube heat exchanger under wet conditions[J]. CIESC Journal, 2020, 71(5): 1986-1994.

图/表 9

图1 析湿工况下湿翅片表面颗粒物沉积过程示意图

Fig.1 Schematic diagram of particle deposition process on wet fin surfaces of heat exchanger under dehumidifying conditions

图2 湿翅片单元上冷凝水捕集颗粒物的示意图

Fig.2 Schematic of particle-capturing by condensate water on wet fin cell

图3 冷凝水控制体中充满颗粒物时的排列方式

Fig.3 Schematic diagram of particle arrangement in condensate water

图4 入射颗粒物碰撞形变示意图

Fig.4 Schematic diagram of incident particle deformation

图5 入射颗粒物与已沉积湿颗粒物之间的碰撞过程示意图

Fig.5 Impact between incident particle and deposited particle

表1 测试样件结构参数

Table 1 Geometric details of test sample

Fin pitch/mm

Tube diameter/mm

Tube pitch/

(mm× mm)

Size/

(mm× mm × mm)

Wavy angle/

(°)

表2 颗粒物及液膜的物性参数

Table 2 Physical properties of particle and liquid film

ρ_p/

(kg·m^-3)

$d ˉ$ _p/

μm

E^*/

(N·m^-2)

y/(N·m^-2)

F_el/N

μ/

(N·s·m^-2)

σ/

(mN·m^-1)

3.8×10¹⁰