翅片管换热器在析湿工况下的积灰特性及对空气侧压降的影响

空调器室内机多数采用翅片管换热器,会因制冷运行过程中表面析湿而粘附灰尘,导致空气流动阻力增大。本文选用空调器中常用的平直翅片、波纹翅片和开窗翅片作为测试样件,翅片间距范围为1.5～2.2 mm,研究了翅片管换热器在析湿工况下的积灰特性及积灰对空气侧压降的影响。结果表明:翅片表面的析湿量决定积灰程度,析湿液滴分布越密集、液桥数量越多,翅片迎风面的堵塞程度越严重且空气侧压降越大。在相同析湿工况下,具有复杂结构的开窗翅片和小翅片间距更容易积灰并增大空气侧压降,因此降低翅片结构复杂程度并适当增大翅片间距有利于空调器的防尘。在积灰过程中,随着换热器表面粉尘沉积量增加,空气侧压降先增大后保持稳定。

Effect on Particle Deposition Characteristics and Air-side Pressure Drop of Fin-and-tube Heat Exchangers under Dehumidifying Conditions

Fin-and-tube heat exchangers are widely used in indoor units of air conditioners. When the indoor unit heat exchanger is served as evaporator, dehumidification may occur on the fin surface and dust particles easily adhere to the wet fin surface, leading to an increase of air flow resistance. In this paper, the particle deposition characteristics on fin-and-tube heat exchangers under dehumidifying conditions and the influence of deposited wet particles on the air-side pressure drop are experimentally studied. The fin types of test samples cover plate fin, wavy fin and louver fin. The range of fin pitch is 1.5-2.2 mm. The results show that the particle deposition amount is determined by the degree of dehumidification, and the particle deposition amount on windward side of fins as well as the air-side pressure drop increase as the amount of condensate droplets and liquid bridges. Louver fin or small fin pitch is more inclined to wet particle deposition as well as the increase of pressure drop and simplifying fin structure or increasing fin pitch is beneficial to wet particle prevention. The air-side pressure drop firstly increased then tended to be stable with the increase of wet particle deposition amount.