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管径变化对蒸发器性能影响的仿真与实验研究
吴极, 王瑾, 王哲旻, 牛臻, 王金鑫, 刘鹏飞
0
(上海理工大学环境与建筑学院)
摘要:
家用空调换热器采用的管径不同,产生的传热效果等性能有差异。采用空气焓差法,对具有相同制冷量的5 mm管径换热器和7 mm管径换热器进行了蒸发工况的实验,并建立了不同管径换热器的仿真计算模型,分析了管径的变化对蒸发器制冷剂侧和空气侧的换热和压降的影响。对比实验与计算结果,发现:1)5 mm换热器空气侧表面传热系数提高了17%;2)在相同制冷量下,5 mm换热器的制冷剂质量流量减少了4.6%,质量流速增大了89.4%,同时由于管壁热流密度的增大,引起了蒸干点的提前;3)以制冷剂达到相同干度时的换热系数作为基准,随着干度的增加,5 mm管的管内换热系数增大到7 mm管的1.43~1.86倍;同时制冷剂的摩擦压降、加速压降和局部压降均为7 mm换热器的3倍,压降引起了蒸发温度降低1.1 ℃。
关键词:  房间空调器  换热器  铜管管径  传热系数  流动压降
DOI:
基金项目:
Simulation and Experimental Study of Tube Diameter Influence on Evaporative Performance of Heat Exchangers
Wu Ji, Wang Jin, Wang Zhemin, Niu Zhen, Wang Jinxin, Liu Pengfei
(School of Environment and Architecture, University of Shanghai for Science and Technology)
Abstract:
The experiments were conducted on 5 mm and 7 mm finned tube heat exchangers with same refrigerating capacity based on enthalpy method. The evaporator simulation model was established to analysis the influence of tube diameter on the heat transfer performance. The results show: 1) the heat transfer coefficient on the air side of the 5 mm tube heat exchanger is 17% higher. 2) With same refrigerating capacity, the refrigerant mass flow rate of 5 mm diameter tubes has a 4.6% reduction and its mass velocity increases by 89.4%, which arises the dry out point in advance. 3) At same vapor quality points, its local heat transfer coefficient increases to 1.43 ~ 1.86 times as that of 7 mm diameter tubes. Meanwhile friction pressure drops, acceleration pressure drops and local pressure drops in 5 mm diameter tubes increase to more than 3 times as those in 7 mm diameter tubes, arising 1.1 ℃ increasing in evaporating temperature.
Key words:  room air-conditioner  heat exchanger  tube diameter  heat transfer coefficient  pressure drops

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