Development And Study On Carbon Dioxide Transcritical Cycle Experimental System With Expander

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.