渔船废热驱动喷射制冷系统中喷射器的性能研究
发布时间：2019-02-11 07:51
【摘要】：喷射式制冷系统主要包括加热器、喷射器、冷凝器、蒸发器以及膨胀阀和循环水泵等设备。由于其具有构造简单、造价低廉、运行可靠、操作方便和节约能源等优点而被人们所青睐。然而其缺点主要为效率低下,通常难以满足制冷需求,而对喷射式制冷系统效率起关键影响的部件是喷射器。喷射器是一种通过使用高压流体来抽吸低压流体的混合动力装置,在工业领域中被广泛使用,虽然喷射器结构较为简单,但其内部的流场极为复杂,使得当前人们对喷射器的性能及流场分布规律的掌握情况较为有限。现有的喷射器研究大都采用一维或二维的分析方法,这些方法不能很好的体现喷射器三维结构及其内部特殊的物理现象。本文以基于废热源制冷为目的的渔船喷射制冷系统的关键部件—喷射器为对象,通过采用CFD模拟与实验相结合,以R236fa为工作流体,研究了喷射器性能,并着重分析了其结构对其性能的影响。模拟所需的喷射器几何结构简化为三维中心对称结构,三维研究可以更加真实地反映喷射器内部的流动特性并得到更多的空间混合及流动信息。喷射器网格划分采用全六面体结构化网格,并采用网格自适应技术捕捉激波,最大程度上提高网格质量及计算的准确性。计算模型选用Shear Stress Transport(SST)模型。通过搭建双热源双极喷射制冷系统实验台,从实验角度来分析喷射器性能,对与其中一组模拟结构相同的喷射器进行实验分析,得出喷射系数随冷凝器压力变化的实验数据,并与模拟结果比较,发现两者结果的平均相对误差为9.6%,模拟结果具有较高的可靠性。经研究表明:喷射器结构对其性能的影响非常明显,在给定工作参数条件下,喷嘴出口端长度D1以及喷射器喷嘴出口与混合段出口之间距离D2均存在一个最佳值,此时喷射系数达到最大;而喷射器性能随其扩散室出口角度?以及喷嘴喉部直径d的增加而降低。该课题的研究,为中国中小型远洋渔船上运用喷射制冷的可行性奠定基础,同时为喷射器三维模拟研究提供思路。
[Abstract]:The ejector refrigeration system includes heater, ejector, condenser, evaporator, expansion valve and circulating water pump. It has the advantages of simple structure, low cost, reliable operation, convenient operation and energy saving. However, the main shortcomings of the system are inefficiency, which is usually difficult to meet the refrigeration requirements, and the ejector plays a key role in the efficiency of the ejector refrigeration system. Ejector is a hybrid power device which uses high-pressure fluid to pump low-pressure fluid. It is widely used in industrial field. Although the structure of ejector is relatively simple, its internal flow field is extremely complex. At present, the performance of ejector and the distribution of flow field are limited. Most of the existing researches on ejectors use one-dimensional or two-dimension analysis methods, which can not well reflect the three-dimensional structure of the ejector and its special physical phenomena. In this paper, the ejector, which is the key component of the fishing vessel ejector refrigeration system based on waste heat source refrigeration, is used as the object. The performance of the ejector is studied by using CFD simulation and experiment, using R236fa as the working fluid. The influence of its structure on its performance is analyzed. The geometry of the ejector needed for simulation is simplified to a three-dimensional centrosymmetric structure. The three-dimensional research can reflect the flow characteristics of the ejector more truly and obtain more spatial mixing and flow information. All hexahedron structured meshes are used in the mesh generation of ejector and the shock waves are captured by mesh adaptive technique. The mesh quality and accuracy of calculation are improved to the greatest extent. The Shear Stress Transport (SST) model is selected for the calculation model. The performance of the ejector is analyzed from the point of view of the experiment by setting up a double heat source bipolar ejector refrigeration system, and the experimental data of the ejector coefficient varying with the condenser pressure are obtained through the experimental analysis of the ejector with the same structure as one of the simulated ones. Compared with the simulation results, it is found that the average relative error of the two results is 9.6, and the simulation results have high reliability. The results show that the effect of ejector structure on its performance is very obvious. Under the given working parameters, there is an optimum value for the length of nozzle exit D1 and the distance between nozzle exit and mixing section exit D2. The jet coefficient reaches the maximum. And the ejector performance depends on the outlet angle of the diffuser chamber? And the nozzle throat diameter d increases and decreases. The research of this subject lays a foundation for the feasibility of using ejector refrigeration on Chinese small and medium-sized ocean-going fishing vessels, and provides a way of thinking for the three-dimensional simulation of ejector at the same time.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U664.87;TB657
本文编号：2419536
[Abstract]:The ejector refrigeration system includes heater, ejector, condenser, evaporator, expansion valve and circulating water pump. It has the advantages of simple structure, low cost, reliable operation, convenient operation and energy saving. However, the main shortcomings of the system are inefficiency, which is usually difficult to meet the refrigeration requirements, and the ejector plays a key role in the efficiency of the ejector refrigeration system. Ejector is a hybrid power device which uses high-pressure fluid to pump low-pressure fluid. It is widely used in industrial field. Although the structure of ejector is relatively simple, its internal flow field is extremely complex. At present, the performance of ejector and the distribution of flow field are limited. Most of the existing researches on ejectors use one-dimensional or two-dimension analysis methods, which can not well reflect the three-dimensional structure of the ejector and its special physical phenomena. In this paper, the ejector, which is the key component of the fishing vessel ejector refrigeration system based on waste heat source refrigeration, is used as the object. The performance of the ejector is studied by using CFD simulation and experiment, using R236fa as the working fluid. The influence of its structure on its performance is analyzed. The geometry of the ejector needed for simulation is simplified to a three-dimensional centrosymmetric structure. The three-dimensional research can reflect the flow characteristics of the ejector more truly and obtain more spatial mixing and flow information. All hexahedron structured meshes are used in the mesh generation of ejector and the shock waves are captured by mesh adaptive technique. The mesh quality and accuracy of calculation are improved to the greatest extent. The Shear Stress Transport (SST) model is selected for the calculation model. The performance of the ejector is analyzed from the point of view of the experiment by setting up a double heat source bipolar ejector refrigeration system, and the experimental data of the ejector coefficient varying with the condenser pressure are obtained through the experimental analysis of the ejector with the same structure as one of the simulated ones. Compared with the simulation results, it is found that the average relative error of the two results is 9.6, and the simulation results have high reliability. The results show that the effect of ejector structure on its performance is very obvious. Under the given working parameters, there is an optimum value for the length of nozzle exit D1 and the distance between nozzle exit and mixing section exit D2. The jet coefficient reaches the maximum. And the ejector performance depends on the outlet angle of the diffuser chamber? And the nozzle throat diameter d increases and decreases. The research of this subject lays a foundation for the feasibility of using ejector refrigeration on Chinese small and medium-sized ocean-going fishing vessels, and provides a way of thinking for the three-dimensional simulation of ejector at the same time.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U664.87;TB657
【参考文献】
相关期刊论文 前1条
1 杨新宇;王金锋;谢晶;;喉部面积比对喷射器性能的影响分析[J];低温与超导;2011年06期
，本文编号：2419536
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