| 摘要: |
| 为研究引射器结构、性能及其内部流动机制对引射系统性能提升的影响，本文设计加工了具有压力测点的不同喷嘴距可视化引射器，并在跨临界CO2引射膨胀制冷实验装置上进行测试，获得了不同喷嘴距下CO2两相引射器的引射系数和压力恢复性能，利用压力传感器测量了主动流喷嘴、混合段和扩压段内的压力分布，利用高速相机拍摄得到了主动流膨胀角度、膨胀长度和相变位置。研究结果表明：喷嘴距会通过膨胀轮廓来影响引射器性能系数：喷嘴距为4 mm时，膨胀长度短，膨胀角度大，压力恢复系数高但引射系数低；适当增大喷嘴距为6 mm和8 mm时，主动流的欠膨胀程度减小，膨胀长度变长，膨胀角度减小，引射系数得到提升；喷嘴距为10 mm时，膨胀角度开始增加，引射系数和压力恢复系数均较低。在本文实验工况下，引射器的最优喷嘴距在6～8 mm之间。 |
| 关键词: 两相引射器 可视化 膨胀轮廓 喷嘴距 |
| DOI： |
| 投稿时间：2021-01-04 修订日期：2021-03-30
|
| 基金项目:国家自然科学基金（51676148）资助项目。 |
|
| Experimental Investigation on the CO2 Two-phase Ejector with Different Nozzle Exit Positions |
| Zhang Xiping,Deng Jianqiang,Li Yafei,He Yang |
| (School of Chemical Engineering and Technology , Xi'an Jiaotong University) |
| Abstract: |
| The ejector is one of the key components of a transcritical CO2 ejector expansion refrigeration system, and the nozzle exit position (NXP) is the main geometric parameter. Therefore, research on the structure, performance, and internal flow mechanism of the ejector is beneficial for improving the performance of the ejector system. In this study, a visualization ejector with different NXPs was designed and manufactured. The entrainment ratio and pressure recovery ratio of the CO2 two-phase ejector with different NXPs were obtained in a transcritical CO2 ejector expansion refrigeration system. Furthermore, the pressure distribution along the primary nozzle, mixing section, and diffuser section was measured using a pressure sensor. Simultaneously, the expansion angle, expansion length, and phase change position of the primary flow were captured using a high-speed camera. According to the experimental results, the performance of the ejector is influenced by the expansion profile. Specifically, the short NXP (4 mm) led to a short expansion length, large expansion angle, and high-pressure recovery ratio, but the corresponding entrainment ratio was relatively low. As the NXP increased to 6 mm and 8 mm, the expansion of the primary flow was more sufficient, the expansion length was longer, the expansion angle was smaller, and the entrainment ratio was improved. A further increase in the nozzle distance to 10 mm contributed to a larger expansion angle as well as a low entrainment ratio and pressure recovery ratio. From the results, the optimal NXP is in the range of 6–8 mm for the ejector under the operating conditions of this study. The results of this study contribute to a better understanding of the internal flow mechanism of the ejector and help to improve its design theory. |
| Key words: two-phase ejector visualization expansion profile nozzle exit position |
