变制冷剂流量制冷系统过热度振荡机理实验研究

发布时间：2018-07-07 11:10

本文选题：电子膨胀阀 + 过热度　；参考：《制冷学报》2017年01期

【摘要】：本文以变制冷剂流量制冷系统实验装置为研究对象,通过改变电子膨胀阀开度、冷冻水侧加热量和冷却水出水温度,对系统过热度振荡机理进行了实验分析。结果表明:1)电子膨胀阀开度较小时(24.7%~25.3%),蒸发器出口过热度振幅在1 K内,随着开度增大(25.6%~26.2%),振幅变大,约为3 K,当开度为26.5%~26.8%时,振幅恢复到1 K以内;2)传热机理的变化是导致过热度振荡的根本原因,影响蒸发器管内沸腾特性的主要参数是蒸发器换热量和质量流量,研究过热度振荡时需将两者综合考虑;3)压比对质量流量的影响较大。在压比增大初期,质量流量逐渐增加,表面传热系数大幅增加,过热度降低;当压比继续增加时,换热机理一直在液膜对流沸腾换热和过热蒸气换热间交替,维持不变。过热度振荡特性在膨胀阀-蒸发器闭环控制时更为复杂,在今后的研究中需要重点关注。
[Abstract]:In this paper, the experimental device of variable refrigerant flow rate refrigeration system is studied. The mechanism of superheat oscillation of the system is analyzed experimentally by changing the opening of electronic expansion valve, adding heat on the side of refrigerating water and the temperature of cooling water effluent. The results show that when the opening of the electronic expansion valve is small (24.725%), the amplitude of superheat at the outlet of the evaporator is within 1 K, and with the increase of opening degree (25.6%), the amplitude becomes larger, about 3 K, and when the opening degree is 26.5-26.8%, The change of heat transfer mechanism is the root cause of superheat oscillation. The main parameters affecting boiling characteristics in evaporator tube are heat transfer and mass flow rate of evaporator. In the study of superheat oscillation, the effect of mass flow rate should be greatly influenced by the combined consideration of the two factors. At the beginning of the increase of the pressure ratio, the mass flow rate increases gradually, the surface heat transfer coefficient increases significantly and the superheat degree decreases, and when the pressure ratio continues to increase, the heat transfer mechanism is kept constant between the convection boiling heat transfer and the superheated steam heat transfer. The characteristics of superheat oscillation are more complex in the closed loop control of expansion valve-evaporator, and should be paid more attention to in the future.
【作者单位】：上海理工大学能源与动力工程学院制冷与低温工程研究所;
【基金】：上海市动力工程多相流动与传热重点实验室项目(1N-15-301-101)资助~~
【分类号】：TB657

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