新型蒸汽压缩/喷射制冷循环系统研究

【作者】 王飞；

【导师】 孙文哲；

【作者基本信息】 上海海事大学 ， 制冷及低温工程， 2007， 硕士

【摘要】 随着人们生活水平的提高,空调的使用日益广泛,建筑能耗也不断增加,能源问题日益突出。节能已成为“十一五”期间的重要任务,其核心目标是在“十一五”期间单位国内生产总值能耗降低20%。与此同时,大量使用机械压缩式制冷系统带来电能消耗、环境污染问题也向人类可持续发展提出了挑战。因此,制冷设备的节能对“十一五”节能目标的实现有着巨大的现实意义和深远的历史意义。本文采用喷射器部分取代常规压缩式制冷系统中的节流装置,冷凝后的高压制冷剂通过喷射器来引射蒸发器中的蒸发的制冷剂蒸汽,从而回收部分制冷剂膨胀能,提高压缩机入口的压力。喷射器通过降低节流阀的入口压力,从而降低膨胀过程的节流损失,最终提高了系统的能效率和(火用)效率。本文主要研究内容如下:首先,本文介绍了常规蒸汽压缩式制冷装置的(火用)分析,分析此装置进行(火用)分析的必要性和减少(火用)损失的途径,并介绍了装置中各部件的(火用)损失数学模型。接着,本文着重对新型压缩/喷射制冷系统进行了分析研究,建立了针对该系统的物理模型、数学模型,并对系统进行分析,计算工质包括R12、R22、R134a、R407C、R404A、R410A等。讨论了不同制冷剂、不同工况和喷射系数对系统性能参数的影响。结果表明:对于各种制冷剂,蒸发温度升高时,系统ε增大;冷凝温度降低时,系统ε增大;喷射系数升高,系统ε现增大后减小。对于R410A来说,系统工况最佳为冷凝温度45℃,蒸发温度为5℃,喷射系数为0.3左右。最后,本文从系统的能效率(ε)、(火用)效率两个方面比较了新型压缩/喷射制冷系统和常规压缩式制冷系统的性能。结果表明:在本文研究工况下,新制冷循环的COP最大值比常规制冷循环提高了大约20%,而(火用)效率大约提高了23%,并得出喷射器在冷凝器温度较高的场合和低温冷水机组或冰蓄冷场合能发挥较大的效果。更多还原

【Abstract】 With the improvement of standard of living, air-conditioner has been more and more popularized, building energy consumption will continue to increase, which makes energy issues more prominent. At the eleven five-year period, Energy saving has already become a significant task. It’s a core objective to decrease energy consume of gross domestic product per unit to percent twenty. At the same time, mechanical compression refrigerators consume a big quantity of electric power and indirectly make the pollution problem sever, which bring forward a great challenge to the human’s sustainable development. With regard to implementation of objective of energy saving, energy saving of refrigerating equipment has enormous realistic and historical significance.In the paper, the ejector partly substitutes a throttle device. High-press refrigerants inject refrigerant of evaporator via ejector, which recovers partly expansion energy of refrigerants and increase pressure of compressor entry. At the same time, ejector decreases pressure of throttle valve entry to decrease throttle loss, which ultimately increase energy efficiency and exergy efficiency of refrigeration system. The following are the main researched contents:Firstly, this paper introduces exergy analysis conventional vapour compression of conventional vapour compression refrigeration system. It analyzes necessity of system’s exergy and approach decreasing exergy loss. This paper also introduce mathematical module of exergy loss of unit’component.Secondly, in the paper, the study of the performance of new compression-eject refrigeration system is carried out. Physical model and mathematical model for this system are established, which uses various refrigerants including R12、R22、R134a、R407C、R404A and R404A etc. The effect of different refrigerant、operating condition and ejecting coefficient is discussed. The results show that the COP rises with the increasing evaporator temperature and decreasing of condensate temperature, but the COP increases at first, and then reduces with the increase of ejecting coefficient. For R410A, the better operating condition is a condenser temperature 30℃, a evaporator temperature, a ejecting coefficient temperature or so 0.3. Ultimately, the performance of the new compression-eject refrigeration system and the conventional vapour compression refrigeration system is compared in two aspects of energy efficiency and exergy efficiency. It was found that for the working condition in the paper, the maximum increase of COP of new compression-eject refrigeration system is up to or so 20% comparing with conventional vapour compression refrigeration system and exergy efficiency is up to or so 23% comparing with conventional vapour compression refrigeration system. It is found that ejector can bring into play a great effect in the higher condensing temperature occasion and cryogenics water chiller occasion or ice thermal storage.更多还原