| 引用本文: | 黄东,冷永强,张振亚.非均匀水流量对热力膨胀阀控制稳定性的影响[J].哈尔滨工业大学学报,2017,49(7):171.DOI:10.11918/j.issn.0367-6234.201603101 |
| HUANG Dong,LENG Yongqiang,ZHANG Zhenya.Effects of water mal-distribution on thermostatic-expansion-valve stability[J].Journal of Harbin Institute of Technology,2017,49(7):171.DOI:10.11918/j.issn.0367-6234.201603101 |
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| 摘要: |
| 为研究热力膨胀阀(TEV)的控制失稳机理，采用TEX2型外平衡式TEV进行实验，在7组非均匀水流量率的情况下，实现TEV控制从稳定到振荡的动态变化.结果表明：当支路2的水流量F2从36.9%递减至27.0%，TEV流量控制特性稳定，蒸发器换热量仅衰减了3.4%；当F2从27.0%降至9.1%，总出口的制冷剂状态由过热变为带液，其出口温度由稳定变波动，且波动幅度持续增大，此时TEV的流量控制失稳，蒸发器换热量衰减了14.1%.支路1过热蒸汽的显热不足以提供支路2带液量完全蒸发所需的潜热，混合后总出口的过热度小于热力膨胀阀的MSS曲线要求的最小过热度，进而导致热力膨胀阀的持续振荡.实验结果可为多流路制冷系统中换热器的设计提供参考.
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| 关键词: 非均匀水流量 多支路蒸发器 热力膨胀阀 振荡 换热量 最小过热度曲线 |
| DOI：10.11918/j.issn.0367-6234.201603101 |
| 分类号:TB 657.9 |
| 文献标识码:A |
| 基金项目:国家自然科学基金(51006079) |
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| Effects of water mal-distribution on thermostatic-expansion-valve stability |
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HUANG Dong,LENG Yongqiang,ZHANG Zhenya
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(School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
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| Abstract: |
| To explore the hunting behavior of the thermostatic-expansion-valve (TEV), dynamic characteristics of the TEV (TEX2 externally balanced type) control-loop ranged from stability to vibration were studied under the selected 7 sets of water mal-distribution experimentally. Results showed that as F2 dropped from 36.9% to 27.0%, the TEV control-loop was stable and the overall evaporator capacity decreased by only 3.4%. As F2 dropped from 27.0% to 9.1%, evaporator overall outlet temperature changed from stability to vibration. Its vibration amplitude increased gradually with the phase transformation from vapor to mist, indicating that hunting behavior of TEV control-loop occurred, and the overall evaporator capacity decreased by 14.1%. The superheated refrigerant gas from Circuit 1 outlet only provided sensible heat and couldn't evaporate the liquid refrigerant out of Circuit 2 into superheated steam. Consequently, refrigerant in the evaporator overall outlet was of a smaller superheat than the necessary minimal stable signal (MSS) of the TEV, even at two-phase state, and would inevitably give rise to the hunting of the TEV -controlled system according to the MSS theory. These experimental results might provide references for the design of the heat exchanger of multi-circuit refrigerating system.
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| Key words: water mal-distribution multi-circuit evaporator thermostatic-expansion-valve vibration evaporator capacity minimum stable signal |
