无泵喷射式制冷系统性能的实验研究

发布时间：2018-03-05 05:00

本文选题：喷射式制冷　切入点：无泵　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：利用低品位热能驱动的制冷系统可以有效减少化石能源的消耗,在传统能源消耗巨大、环境问题越加显著的今天,越来越受到人们的关注。喷射式制冷系统在有效利用太阳能热和各种余热等低品位热能的同时,可以使用水等天然工质进行制冷,是理想的环保型制冷系统之一。除此之外,喷射制冷系统还具有结构简单、初投资低、运行稳定等优点。为了提高喷射式制冷系统的性能,实现喷射式制冷系统完全由热能驱动的目标,本文主要研究了无泵阀切换喷射式制冷系统的运行规律和工作特性,并在理论研究的基础上进行了实验验证。研究内容如下:1)介绍了喷射器的工作原理、喷射式制冷系统的研究现状,以及影响喷射式制冷系统性能的主要因素。对已有无泵阀切换喷射式制冷系统进行了改进和完善,提升了系统的控制与测量精度,简化了操作过程。2)采用一维等压模型对喷射器进行了理论研究与工作参数模拟,得到了发生压力、冷凝压力和蒸发压力对系统性能的影响。在分析储液罐容积对系统稳定性的影响的基础上对储液罐容积进行了优化。3)通过对无泵阀切换喷射式制冷系统工作原理的分析,认为该系统的最佳循环过程应该是储液罐蓄满水后再回水,回水必须完全。所以,系统蓄水时间和回水时间应该根据具体工况和储液罐容积来设定。在系统最佳状态下,无泵阀切换喷射式制冷系统的性能随发生压力的升高先升高后下降,发生压力为130 kPa左右时系统性能达到最佳;蒸发压力越高系统性能越好;冷凝压力小于临界背压时,冷凝压力的变化对系统性能几乎没有影响,当冷凝压力大于临界背压时,随冷凝压力升高系统性能急剧下降。4)实验结果和理论研究都揭示了无泵阀切换喷射式制冷系统在工作过程中发生压力、冷凝压力与蒸发压力的变化对系统运行参数与性能的影响规律。理论研究与实验结果具有良好的一致性,为深入探究无泵阀切换喷射式制冷系统的工作特性打下一定的基础。
[Abstract]:The refrigeration system driven by low-grade heat energy can effectively reduce the consumption of fossil energy. More and more people pay more and more attention to it. The ejector refrigeration system is one of the ideal environmental protection refrigeration systems, which can use natural refrigerants such as water and other low-grade heat energy to make effective use of solar energy and all kinds of waste heat. The ejector refrigeration system also has the advantages of simple structure, low initial investment, stable operation and so on. In order to improve the performance of the ejector refrigeration system, it can realize the goal that the ejector refrigeration system is completely driven by heat energy. In this paper, the operating rules and working characteristics of the switched ejector refrigeration system without pump valves are studied, and the experimental verification is carried out on the basis of theoretical research. The work principle of the ejector is introduced as follows: 1. The present research situation of jet refrigeration system and the main factors affecting the performance of jet refrigeration system have been improved and perfected, and the control and measurement accuracy of the system has been improved. The operation process is simplified. 2) A one-dimensional isobaric model is used to study the ejector theoretically and simulate the working parameters, and the pressure is obtained. The effect of condensing pressure and evaporation pressure on the system performance. Based on the analysis of the effect of tank volume on system stability, the tank volume is optimized. 3) the working principle of the switched jet refrigeration system without pump valves is analyzed. It is considered that the optimal circulation process of the system should be that the tank is filled with water, and the backwater must be returned completely. Therefore, the storage time and backwater time of the system should be set according to the specific working conditions and the volume of the tank, and in the best condition of the system, The performance of the switched injection refrigeration system without pump valve increases first and then decreases with the increase of pressure. The system performance reaches the best when the occurrence pressure is about 130 kPa; the higher the evaporation pressure, the better the system performance; when the condensing pressure is less than the critical back pressure, The change of condensing pressure has little effect on the performance of the system. When the condensing pressure is greater than the critical back pressure, The experimental results and theoretical studies show that the pressure of the switched injection refrigeration system without pump valves occurs in the working process, and the performance of the system decreases sharply with the increase of condensing pressure. The effect of condensing pressure and evaporation pressure on the operating parameters and performance of the system is in good agreement with the experimental results, which lays a foundation for further exploring the working characteristics of the switched jet refrigeration system without pump valves.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB657

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