發(fā)布時(shí)間：2018-05-14 02:30

  本文選題：引射器 + 兩相流��； 參考：《天津商業(yè)大學(xué)》2015年碩士論文

【摘要】：在制冷系統(tǒng)中使用兩相流引射器來(lái)代替?zhèn)鹘y(tǒng)制冷系統(tǒng)中的膨脹閥,可以回收高壓工質(zhì)的壓力能,提升壓縮機(jī)進(jìn)氣壓力,降低壓縮機(jī)功耗。本文首先用CFD軟件模擬了兩相流引射器的性能,分別模擬引射器的結(jié)構(gòu)尺寸和運(yùn)行工況對(duì)其性能的影響情況。其次對(duì)以R134a為工質(zhì)的兩相流引射制冷系統(tǒng)的性能進(jìn)行了實(shí)驗(yàn)研究,在定工況條件下分析了引射器第一段噴嘴擴(kuò)張角、第一段噴嘴喉部面積、第二段噴嘴喉部面積對(duì)系統(tǒng)性能的影響。之后保持引射器的結(jié)構(gòu)參數(shù)不變,實(shí)驗(yàn)分析了冷凝溫度、蒸發(fā)溫度對(duì)系統(tǒng)性能的影響。最后對(duì)傳統(tǒng)制冷系統(tǒng)和兩相流引射制冷系統(tǒng)性能在相同工況下進(jìn)行對(duì)比,并將模擬結(jié)果與實(shí)驗(yàn)結(jié)果進(jìn)行了比較。主要研究結(jié)論如下:(1)實(shí)驗(yàn)結(jié)果表明,對(duì)于兩段式噴嘴引射器,隨著第一段噴嘴擴(kuò)張角的減小,引射比先減小后增加。當(dāng)?shù)谝欢螄娮鞌U(kuò)張角達(dá)到3°時(shí),被引射流流量達(dá)到最大,此時(shí)引射比最高。同時(shí)模擬結(jié)果也顯示,第一段噴嘴擴(kuò)張角的減小會(huì)帶來(lái)引射比的提升。第一段噴嘴喉部面積的增加也會(huì)帶來(lái)系統(tǒng)COP的提升。(2)模擬和實(shí)驗(yàn)結(jié)果均表明,隨著引射器第二段喉部面積的增加,引射比逐漸升高,在第二喉部直徑為1.9mm時(shí),引射比最高。系統(tǒng)COP隨著第二段喉部面積的增加先升高后降低,在第二喉部直徑為1.8mm時(shí),系統(tǒng)COP最大。(3)實(shí)驗(yàn)結(jié)果表明,對(duì)于固定結(jié)構(gòu)尺寸的引射器,當(dāng)冷凝溫度降低時(shí),傳統(tǒng)制冷系統(tǒng)和兩相流引射制冷系統(tǒng)的COP在整體上都呈升高趨勢(shì)。當(dāng)冷凝溫度達(dá)到43℃時(shí),引射器的使用會(huì)使傳統(tǒng)制冷系統(tǒng)COP提高3.4%。蒸發(fā)溫度升高也會(huì)帶來(lái)兩相流引射制冷系統(tǒng)COP的提升。(4)通過(guò)模擬與實(shí)驗(yàn)結(jié)果的對(duì)比可以看出,引射比均隨著冷凝溫度降低而減小,隨著蒸發(fā)溫度的降低而減小,模擬結(jié)果與實(shí)驗(yàn)結(jié)果的變化趨勢(shì)一致。但是與實(shí)驗(yàn)結(jié)果相比,模擬結(jié)果偏高。(5)實(shí)驗(yàn)結(jié)果表明:在蒸發(fā)溫度為-1℃、冷凝溫度為50℃的工況下,當(dāng)?shù)谝欢螄娮鞌U(kuò)張角為3°、第二喉部直徑為1.8mm、第一喉部直徑為2.1mm時(shí),兩相流引射制冷系統(tǒng)的COP最高。(6)分別使用二維和三維引射器模型進(jìn)行模擬,通過(guò)對(duì)兩者進(jìn)行比較后發(fā)現(xiàn),模擬的引射比變化趨勢(shì)一致,與實(shí)驗(yàn)結(jié)果相比,兩者誤差相差不大。但使用二維引射器模型進(jìn)行模擬計(jì)算時(shí),能夠減小計(jì)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 擄, 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，

本文編號(hào)：1885941