带有两段喷嘴的可调式两相流引射器特性研究

发布时间：2018-05-14 02:30

  本文选题：引射器 + 两相流　； 参考：《天津商业大学》2015年硕士论文

【摘要】：在制冷系统中使用两相流引射器来代替传统制冷系统中的膨胀阀,可以回收高压工质的压力能,提升压缩机进气压力,降低压缩机功耗。本文首先用CFD软件模拟了两相流引射器的性能,分别模拟引射器的结构尺寸和运行工况对其性能的影响情况。其次对以R134a为工质的两相流引射制冷系统的性能进行了实验研究,在定工况条件下分析了引射器第一段喷嘴扩张角、第一段喷嘴喉部面积、第二段喷嘴喉部面积对系统性能的影响。之后保持引射器的结构参数不变,实验分析了冷凝温度、蒸发温度对系统性能的影响。最后对传统制冷系统和两相流引射制冷系统性能在相同工况下进行对比,并将模拟结果与实验结果进行了比较。主要研究结论如下:(1)实验结果表明,对于两段式喷嘴引射器,随着第一段喷嘴扩张角的减小,引射比先减小后增加。当第一段喷嘴扩张角达到3°时,被引射流流量达到最大,此时引射比最高。同时模拟结果也显示,第一段喷嘴扩张角的减小会带来引射比的提升。第一段喷嘴喉部面积的增加也会带来系统COP的提升。(2)模拟和实验结果均表明,随着引射器第二段喉部面积的增加,引射比逐渐升高,在第二喉部直径为1.9mm时,引射比最高。系统COP随着第二段喉部面积的增加先升高后降低,在第二喉部直径为1.8mm时,系统COP最大。(3)实验结果表明,对于固定结构尺寸的引射器,当冷凝温度降低时,传统制冷系统和两相流引射制冷系统的COP在整体上都呈升高趋势。当冷凝温度达到43℃时,引射器的使用会使传统制冷系统COP提高3.4%。蒸发温度升高也会带来两相流引射制冷系统COP的提升。(4)通过模拟与实验结果的对比可以看出,引射比均随着冷凝温度降低而减小,随着蒸发温度的降低而减小,模拟结果与实验结果的变化趋势一致。但是与实验结果相比,模拟结果偏高。(5)实验结果表明:在蒸发温度为-1℃、冷凝温度为50℃的工况下,当第一段喷嘴扩张角为3°、第二喉部直径为1.8mm、第一喉部直径为2.1mm时,两相流引射制冷系统的COP最高。(6)分别使用二维和三维引射器模型进行模拟,通过对两者进行比较后发现,模拟的引射比变化趋势一致,与实验结果相比,两者误差相差不大。但使用二维引射器模型进行模拟计算时,能够减小计算量。
[Abstract]:Two-phase flow ejector is used to replace the expansion valve in the traditional refrigeration system, which can recover the pressure energy of the high pressure working medium, increase the inlet pressure of the compressor and reduce the power consumption of the compressor. In this paper, the performance of two-phase flow ejector is simulated by CFD software, and the influence of structure size and operating condition of ejector on its performance is simulated respectively. Secondly, the performance of two-phase flow ejector refrigeration system with R134a as working fluid is studied experimentally. The expansion angle of the first nozzle and the throat area of the first nozzle of the injector are analyzed under constant working conditions. The influence of the throat area of the second stage nozzle on the performance of the system. The influence of condensation temperature and evaporation temperature on the system performance is analyzed experimentally. Finally, the performance of the traditional refrigeration system and the two-phase flow ejector refrigeration system are compared under the same working conditions, and the simulation results are compared with the experimental results. The main conclusions are as follows: (1) the experimental results show that the ejection ratio decreases first and then increases with the decrease of the expansion angle of the first nozzle for the two-stage nozzle ejector. When the expansion angle of the first nozzle reaches 3 掳, the flow rate of the induced jet reaches the maximum and the ejection ratio is the highest. The simulation results also show that the increase of ejection ratio will be caused by the decrease of the expansion angle of the first nozzle. The results of simulation and experiment show that with the increase of the area of the second stage of the injector, the ejection ratio increases gradually, and the ejection ratio is the highest when the diameter of the second throat is 1.9mm. With the increase of laryngeal area in the second stage, the COP of the system first increased and then decreased. When the diameter of the second larynx was 1.8mm, the system COP was the largest. The experimental results showed that for the injector with fixed structure size, when the condensation temperature was reduced, The COP of traditional refrigeration system and two-phase flow ejector refrigeration system is increasing as a whole. When the condensing temperature reaches 43 鈩，

本文编号：1885941