双级喷射式制冷系统不可逆热力学损失分析

发布时间：2018-06-05 11:37

本文选题：喷射制冷系统 + 性能优化　；参考：《广西大学》2017年硕士论文

【摘要】：随着能源紧张及环境污染等问题的日益突出,从节能的角度去提高能源利用率,进而改善用能环境显得越发重要。在喷射制冷系统、真空装置、化工生产中喷射器均有较为广泛的应用。通过采用不可逆热力学中熵产分析和(火用)分析的原理,将喷射器应用领域拓展到制冷系统的实际不可逆循环过程,如传热、传质、扩散等。本文基于热力学理论对双级喷射制冷系统的不可逆性损失进行了深入研究,依靠动量、质量和能量守恒方程,推导出双级喷射制冷系统的熵平衡及熵产方程,分析了其内部流体流动过程各个部件的熵产和(火用)损失的分部情况。熵能够用来描述自然界各种运动形式转化的数量、方向和不可逆性。本文在分析热力学第一、第二定律的基础上,重点研究了两级串联式喷射制冷系统的研究与进展,着重介绍了熵分析方法在喷射器中的发展趋势和应用前景,并对比了在不同的发生温度、蒸发温度和冷凝温度下,运用不同制冷剂时制冷系统的喷射系数、性能系数以及机械性能系数的变化趋势。分析了喷射制冷系统各部件不可逆损失的分布规律,同时也分析了操作参数变化对系统各部件熵产的影响情况,进而能够准确地确定出使系统性能系数较佳同时满足总熵产最小的运行参数,即系统工作性能最优的工况。热力学系统涉及热量和能量的转换过程,基于热力学系统中的熵产及?损失分析法在喷射制冷系统中的应用已逐渐被国内外一些学者所研究。与利用热力学第一定律中的三大守恒方程(质量、能量、动量守恒)的传统设计方法相比,这种方法的提出在喷射制冷系统中各个部件能量损耗上的分析更为客观全面。掌握喷射制冷技术的研究方法并进行理论分析,有助于推动喷射制冷领域新技术的发展,为其走向更广泛的实用化奠定了坚实的理论基础。如何选用合适的制冷剂是改善双级喷射制冷系统性能的有效手段,随着能源的过度消耗及日益短缺问题逐渐引起人们的重视,利用低品位热源作为动力驱动的喷射制冷方式,将会得到进一步的研究及应用,本文的相关研究为双级喷射制冷系统的性能最优化指明了方向。
[Abstract]:With the problems of energy shortage and environmental pollution becoming more and more prominent, it is more and more important to improve the energy efficiency from the point of view of energy saving, and then to improve the environment of energy use. The ejector is widely used in ejector refrigeration system, vacuum device and chemical industry. By using the principles of entropy production analysis and exergy analysis in irreversible thermodynamics, the application of ejector is extended to the actual irreversible cycle process of refrigeration system, such as heat transfer, mass transfer, diffusion and so on. Based on the thermodynamic theory, the irreversibility loss of two-stage ejector refrigeration system is studied in this paper. Based on the conservation equations of momentum, mass and energy, the entropy equilibrium and entropy production equations of two-stage jet refrigeration system are derived. The entropy production and exergy loss of each component in the internal fluid flow process are analyzed. Entropy can be used to describe the quantity, direction and irreversibility of the transformation of various forms of motion in nature. Based on the analysis of the first and second laws of thermodynamics, this paper focuses on the research and development of two-stage series ejector refrigeration system, and emphatically introduces the development trend and application prospect of entropy analysis method in ejector. The variation trends of ejection coefficient, performance coefficient and mechanical performance coefficient of refrigeration system with different refrigerants were compared at different temperature, evaporation temperature and condensation temperature. The distribution law of irreversible loss of each component of the ejector refrigeration system is analyzed, and the influence of the operating parameters on the entropy production of each component of the system is also analyzed. Furthermore, it is possible to accurately determine the operating parameters which make the system performance coefficient better and satisfy the minimum total entropy production, that is, the optimal operating condition of the system performance. Thermodynamic systems involve the conversion of heat and energy, based on entropy production and? The application of loss analysis in ejector refrigeration system has been studied by some scholars at home and abroad. Compared with the traditional design method using the three conservation equations (mass, energy, momentum conservation) of the first law of thermodynamics, the proposed method is more objective and comprehensive in the analysis of the energy loss of each component in the ejector refrigeration system. Mastering the research methods and theoretical analysis of jet refrigeration technology will help to promote the development of new technology in the field of jet refrigeration and lay a solid theoretical foundation for its wider application. How to select suitable refrigerant is an effective means to improve the performance of two-stage ejector refrigeration system. With the excessive consumption of energy and the increasing shortage of energy, people pay more and more attention to the use of low-grade heat source as a power-driven jet refrigeration method. Further research and application will be carried out. The research in this paper points out the direction of performance optimization of two-stage ejector refrigeration system.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB657

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