| 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。 |
| 关键词: 电子膨胀阀 过热度 系统振荡 |
| DOI： |
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| 基金项目:上海市动力工程多相流动与传热重点实验室(1N-15-301-101) 项目资助。 |
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| Experiment on Hunting Mechanism of Superheated Temperature of a Variable Refrigerant Volume Refrigeration System |
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Yu Zhongyang, Tao Leren, Wang Chao, Sheng Bingjie
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| (Institute of Refrigeration and Cryogenics, School of Energy and Power Engineering, University of Shanghai for Science and Technology) |
| Abstract: |
| To experimentally investigate the hunting mechanism of superheated temperature of a variable refrigerant volume refrigeration system, the opening of electronic expansion valve, the capacity of chilled water and the outlet temperature of cooling water are changed. The results show that when the opening of electronic expansion valve is at 24.7 %-25.3 %, the humting amplitude of superheated temperature is less than 1 K. With the opening increasing (25.6%-26.2%), the humting amplitude is about 3 K. When the opening is at 26.5%-26.8%, the amplitude goes back to less than 1 K. Moreover, the change of heat transfer in evaporator is the primary cause to hunting of superheated temperature, and heating load and refrigerant mass flow are the important parameters for in-tube boiling heat transfer, and both of them should be considered in the investigation for hunting of superheated temperature. In addition, pressure ratio has greater effect on refrigerant mass flow. When the system is at the first stage of increasing pressure ratio, the mass flow rate of refrigerant also increases, and the surface coefficient of heat transfer sharply increases while superheated temperature decreases. When the pressure ratio is sequentially increasing, the mechanism of heat transfer keeps alternation between convective boiling of liquid film and heat transfer of superheated vapor. The mechanism of hunting of superheated temperature for closed-loop control of expansion valve-evaporator is more complicated, which should be focused in later research. |
| Key words: electronic expansion valve superheated temperature hunting |
