冰箱微通道换热器积灰机理研究

Mechanism Investigation of Air-side Fouling on Micro-channel Heat Exchanger for Refrigerator

冰箱微通道换热器表面灰尘沉积会导致空气侧压降增加,造成换热性能衰减。本文通过搭建微通道换热器积灰模拟实验台,研究了风速、灰尘种类、相对湿度、是否带电4个因素对微通道换热器积灰的影响。结果表明:低风速下,灰尘沉积在翅片迎风表面,较高风速时,积灰向翅片后缘扩展。粉末状灰尘几乎不能堆积,随着灰尘中纤维比例的增加,积灰速度也越来越快。当风速为1 m/s,风机固定功率下,100%颗粒、95%颗粒+5%纤维、92%颗粒+5%纤维+3%长纤维3种不同灰尘工况时,空气侧压降增长率分别为8.8%、451.4%、524.9%。95%颗粒+5%纤维和92%颗粒+5%纤维+3%长纤维不同灰尘工况下风量衰减率分别为31.6%和48.7%。当相对湿度为45%和65%时,空气侧压降增长率分别为451.4%和385.6%,风量衰减率分别为31.7%和26.4%。不带电和直流电5 V工况下的空气侧压降增加率分别为385.6%和278.3%,风量衰减率分别为26.4%和18.4%。

The air-side pressure drop of micro-channel heat exchanger(MHE)is increased and the heat exchange performance is attenuated when the MHE is covered with dust particles.In this study,a visual experimental rig was set up to investigate the effect of air velocity,type of dust,relative humidity and whether the MHE is charged or not on dust accumulation.The experimental results indicate that dust particles were mostly deposited on the windward side of the slit fins and at the front part of the tubes at an air velocity of 1 m/s.The dust extended to the trailing edge of the fin at higher wind speed.When only particle dust was present,dust could hardly accumulate.However,as the fiber content increased,the particle-deposition process accelerated.Under the conditions of 100%particle,95%particle+5%fiber,and 92%particle+5%fiber+3%long fiber,the air-side pressure drop were increased by 8.8%,451.4%,and 524.9%,respectively.Under the conditions of 95%particle+5%fiber and 92%particle+5%fiber+3%long fiber,the air volume were decreased by 31.6%and 48.7%.When the air relative humility was 45%and 65%,the air-side pressure drop were increased by 451.4%and 385.6%,and the air volume were decreased by 31.7%and 26.4%.When the MHE was not charged or was charged by an direct current at 5 V,the air-side pressure drop were increased by 385.6%and 278.3%,and the air volume were decreased by 26.4%and 18.4%,respectively.