【作者】 邢英丽；

【导师】 马一太； 李敏霞；

【作者基本信息】 天津大学 ， 工程热物理， 2004， 硕士

【摘要】 本文以自然工质CO2跨临界循环为研究对象，重点对CO2跨临界循环膨胀机实验系统中的主要装置进行理论分析和实验研究，为其向实用化迈进提供理论基础和实践经验。根据实验数据和实验运行情况，对CO2跨临界循环中的压缩机、气体冷却器以及蒸发器的效率和性能进行了分析和研究。对于CO2压缩机，提出了选用合适的润滑油、提高关键零件的加工精度和强度、使用双级压缩以及减小泄漏损失等提高效率的措施，并分析了使用变频技术的可行性和意义。针对气体冷却器和蒸发器的传热系数偏低和结构上存在的不足，本文提出了一种新型集成管箱型管壳式换热器的设计方案。对CO2跨临界循环的膨胀功回收方式进行了理论分析，主要分析了膨胀机与压缩机同轴、输出的机械功直接驱动压缩机的膨胀功回收方式。研究表明，完全用膨胀机驱动双级压缩的高压级这种形式的系统循环性能系数接近最优值，而膨胀机与主压缩机同轴、为主压缩机提供一部分输入功率的双级压缩方式可以最大限度的提高系统的能效。对摆动转子式膨胀机进行了实验研究，发现样机运行平稳。通过实验数据分析，得出了膨胀机的运行特性，以及外部参数变化对膨胀机和系统运行的影响。实验结果也表明了膨胀机存在最佳转速使膨胀机的输出功达到最大。更多还原

【Abstract】 The carbon dioxide transcritical cycle system is the subject of the dissertation. The main equipments of the carbon dioxide transcritical cycle system with expander are studied theoretically and experimentally. According to the experimental data and running, the efficiency and performance of the compressor, gas cooler and evaporator in the carbon dioxide transcritical cycle system is analyzed. In order to improve the efficiency of the carbon dioxide compressor, the measures, such as selecting appropriate lubricant, enhancing machining precision and intensity of key parts, using two-stage compression and reducing leakage, are put forward. On the other hand, frequency conversion technology can be applied. A new-style shell-and-tube exchanger with integrated tube-box is designed to solve the low heat-transfer coefficient and deficient structure of the gas cooler and evaporator.In this paper, the methods of power recovery of carbon dioxide transcritical cycle system are discussed theoretically. The method, in which the expander is the same shaft with the compressor and its output directly drives compressor, is analyzed. The research shows that the coefficient of performance of the system can approach the optimum value when the expander completely drives the second stage compressor for the two-stage compression system. Also when the expander is connected to the main compressor and supplies a part of input power in the two-stage compression system, the coefficient of performance of the system can reach the highest point.The experiments on the swing expander in the carbon dioxide transcritical cycle system have been conducted. By the testing, the characteristics of the performance of the expander and the influence on the expander and system of external parameter are obtained. The experiments indicate the conclusion that there is the optimal rotate speed for the maximum output of expander.更多还原