喷射器数值模拟及喷射特性的研究

发布时间：2018-07-11 15:21

本文选题：喷射器 + CFD模拟　；参考：《大连理工大学》2014年硕士论文

【摘要】：中国已成为世界能源消耗大国,开发先进的能源利用技术是我国社会经济发展的重要课题。喷射式热泵和喷射式制冷的原理相同,是利用低品位热源、提高能源利用率的两种方式。本文研究的喷射器是这两种系统的重要组成部分。喷射器结构简单、无运动部件、维护成本低、性能可靠、工质范围广。唯一的缺点是效率相较压缩式热泵和压缩制冷机偏低。使用CFD软件Fluent模拟喷射器内部工质的流动过程,提高喷射器的制冷和制热效率,最小化操作成本,是本文研究的主要问题。本文主要研究工作为： (1)根据气体动力学设计理论,对广西某造纸厂热泵系统中的喷射器进行结构设计。一维传统理论无法分析喷射器内部详细流场,本文利用CFD模拟软件Fluent的优点,模拟喷射器内部流场分布,通过改变喷射器的操作参数和几何参数,探究制约喷射器性能的主要因素。 (2)与传统喷射器结构的改进方法相比,改型喷嘴喷射器具有改动小,成本低,不同增强结构易于更换,可应用于小型喷射器等优点,在工业生产中应用前景光明。本文以某厂的蒸汽喷射式热泵为例,对喷射器喷嘴进行改进,效果显著。分析了采用后缘增强型喷嘴的喷射器流场结构,并对增强喷嘴提高喷射器性能的原理进行了讨论。 (3)在喷射式制冷系统中,喷射器的性能除了受几何构造和工作条件的影响外,还受制冷剂的制约。本文引入制冷剂的实际物性,使用CFD技术数值模拟了喷射器内流场分布和制冷系统的性能,模拟结果与实验结果的误差低于5%,并在此基础上研究了沸点相近的绿色环保型制冷剂R245ca、R245fa和R236ea的喷射制冷性能。模拟结果表明,R245ca、R245fa和R236ea可作为R123的合适替代制冷剂。
[Abstract]:China has become a major energy consuming country in the world, and developing advanced energy utilization technology is an important subject in China's social and economic development. The principle of jet heat pump is the same as that of jet refrigeration. It is two ways to improve energy efficiency by using low grade heat source. The ejector studied in this paper is an important part of these two systems. The ejector has simple structure, no moving parts, low maintenance cost, reliable performance and wide range of working fluids. The only drawback is that the efficiency is lower than that of compression heat pumps and compression refrigerators. Using CFD software fluent to simulate the flow process of the working fluid in the ejector, to improve the efficiency of cooling and heating of the ejector, and to minimize the operating cost are the main problems studied in this paper. The main work of this paper is as follows: (1) according to the theory of gas dynamic design, the ejector in the heat pump system of a paper mill in Guangxi is designed. The traditional one-dimensional theory can not analyze the detailed flow field inside the ejector. This paper uses the advantage of CFD simulation software fluent to simulate the flow field distribution in the ejector by changing the operating and geometric parameters of the ejector. The main factors that restrict the performance of the injector are explored. (2) compared with the traditional method of improving the structure of the injector, the modified nozzle injector has the advantages of small modification, low cost, easy replacement of different reinforced structures, and can be applied to small injectors, etc. There are bright prospects for application in industrial production. In this paper, the steam jet heat pump in a factory is taken as an example to improve the injector nozzle, and the effect is remarkable. The flow field structure of ejector with rear edge enhanced nozzle is analyzed, and the principle of enhancing nozzle to improve the performance of ejector is discussed. (3) in the ejector refrigeration system, The performance of ejector is not only affected by geometry and working conditions, but also restricted by refrigerant. In this paper, the actual physical properties of the refrigerant are introduced, and the flow field distribution in the ejector and the performance of the refrigeration system are numerically simulated by CFD technique. The error between the simulation results and the experimental results is less than 5. On this basis, the ejection refrigeration performance of the green environmental refrigerants R245CaN R245fa and R236ea with similar boiling points are studied. The simulation results show that R245CaN R245fa and R236ea can be used as suitable alternative refrigerants for R123.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB657

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