面向冷藏车制冷的两级喷射器研究

发布时间：2018-04-19 10:18

  本文选题：喷射器 + 冷藏车　； 参考：《山东大学》2017年硕士论文

【摘要】：随着经济的快速发展,人们的生活水平有了显著提高,因此对食品的品质和多样性提出了更高的要求,与之密切相关的冷链物流业也进入了高速发展期。但作为运输载体的冷藏车,尤其是其制冷系统能耗大,燃料利用率低,加剧了能源紧张问题。由于结构简单、成本低、能耗小等特点,喷射式制冷系统在众多制冷方法中独具优势,但是有限的升压能力成为制约喷射式制冷系统应用到冷藏车的瓶颈。本文提出了一种较大升压能力的两级喷射器,为将喷射式制冷系统应用到冷藏车上进行了有益探索。该研究对冷藏车的节能减排有重要的理论及应用价值。首先,在设计工况下提出了一种两级喷射器的设计方法。选择带有实验数据,国际公认的喷射器模型作为原型,通过数值模拟的方式对原型喷射器进行了建模和基于实验数据的校正,找到了快速高效的数值模拟方法。在原型喷射器的基础上,依据工况,通过改变影响喷射器性能的喉嘴比和NXP等关键结构尺寸,分别设计了第一级和第二级喷射器。同时依据第一级和第二级喷射器串联的原则,将第一、二级喷射器整合成两级喷射器,并建立了该两级喷射器的三维模型。其次,以R134a作为制冷剂,在工作流体温度为63～74℃,蒸发温度为-24～0℃范围内,对建立的两级喷射器模型进行了性能分析。研究了两级喷射器内部的速度场、压力场、温度场等分布,同时对两级喷射器内部的激波位置进行了捕捉。还研究了工作流体、引射流体及出口工况变化时,两级喷射器的性能变化,找到了两级喷射器工作条件变化对其性能的影响规律。研究发现:1)当两级喷射器的二次流压力恒定时,临界背压随着一次流压力的增加而增加,而两级喷射器的最大喷射系数却随着一次流压力的增加而逐渐减小;2)当一次流压力变大时,两级喷射器的临界背压和最大喷射系数都随着二次流压力的增加而变大;3)当两级喷射器的引射流体压力和背压都恒定时,两级喷射器的喷射系数伴随工作流体压力的增加先增大后减小,存在一个最大喷射系数,同时在饱和状态下,蒸发温度分别为-22℃、-20℃、-18℃时,相应的最大喷射系数分别为0.0736、0.0761、0.0813。最后,对冷藏车厢体不同温区下冷藏车总耗冷量进行了分析。通过计算得到冷藏车厢体温度分别为0℃、-5℃、-14℃和-18℃时冷藏车的总耗冷量分别为7.69kw、9.21kw、11.94kw、13.53kw。而冷藏车排量都比较大,其废热量一般在20kw以上,因此冷藏车的废热量能够满足喷射式制冷需要。综上,通过对设计的两级喷射器的研究,表明将喷射制冷技术应用到冷藏车上实现节能减排的方法是可行的,本研究作为废热驱动喷射式制冷系统在冷藏车上的应用具有重要的指导意义。
[Abstract]:With the rapid development of economy, people's living standard has been improved significantly, so the quality and diversity of food are required higher, and the cold-chain logistics industry, which is closely related to it, has also entered a period of rapid development.However, refrigerated vehicle as a carrier, especially its refrigeration system has a large energy consumption and low fuel utilization ratio, which exacerbates the problem of energy shortage.Because of its simple structure, low cost and low energy consumption, the ejector refrigeration system has unique advantages in many refrigeration methods, but the limited boost capacity has become a bottleneck for the application of jet refrigeration system to refrigerated vehicles.In this paper, a two-stage ejector with high boost capacity is proposed, which is useful for the application of ejector refrigeration system to refrigerated vehicles.This study has important theoretical and practical value for energy saving and emission reduction of refrigerated vehicles.Firstly, a design method of two-stage ejector is proposed under the design condition.The internationally recognized ejector model with experimental data was selected as the prototype. The prototype ejector was modeled and calibrated based on experimental data by numerical simulation, and a fast and efficient numerical simulation method was found.Based on the prototype ejector, the first stage and the second stage of the ejector are designed by changing the throat nozzle ratio and the key structure size of NXP, which affect the performance of the ejector.At the same time, according to the principle of the first and second stage ejector in series, the first and second stage ejector is integrated into two stage ejector, and the three-dimensional model of the two stage ejector is established.Secondly, using R134a as refrigerant, the performance of the two-stage ejector model is analyzed in the range of working fluid temperature of 6374 鈩，

本文编号：1772682