Study On Performance Comparative Of Transcritical CO₂ Booster System

With the global elimination of ODS,the ozone layer protection work has achieved initial results,and the global environmental protection situation has undergone profound changes,greenhouse gas emissions and global warming has replaced the ozone layer damage to the current stage of the world's environmental protection tasks and topics.In response to the adverse effects of global warming on human economic and social development,the current international community's efforts to limit and reduce the use and consumption of HFCs are on the rise.In the global environment of the elimination of fluorine-containing greenhouse gases,carbon dioxide as an alternative refrigerant,with its unique advantages in the field of refrigeration has been more and more applications in a variety of complex occasions including a variety of systems: cascade systems,secondary systems and transcritical systems.The application of the system has a unique advantage in reducing the adverse effects of the refrigeration system on the environment.The energy efficiency of the system has a direct impact on its development and application.In this paper,three kinds of transcritical carbon dioxide systems with basic booster system,booster system with parallel compression and booster system with mechanical subcooling are analyzed theoretically.By understanding the research status of foreign related topics and the analysis of thermal cycle theory,the following conclusions are drawn:(1)For the basic booster system,with the gas cooler outlet temperature changing,the existence of the optimal discharge pressure makes the system COP maximum,and the lower the outlet temperature,the optimal discharge pressure is lower;With the increase intermediate pressure,the cooling capacity of the system is decreasing,and the COP of the basic booster system is gradually reduced,and the lower the outlet temperature of the gas cooler,the more obvious the COP decline.(2)When the outlet temperature of the gas cooler in the booster system with parallel compression is higher than the critical temperature,the system has the optimal discharge pressure and the intermediate pressure to maximize the system COP.When the outlet temperature of the air cooler is 32 ?,the optimum pressure are 80 bar and 35 bar respectively.The optimum pressure are 90 bar and 40 bar when the outlet temperature of the air cooler is 37 ?.(3)The mechanical supercooling system can enhance the COP of the pressurization system by 2.5%,9.3%,12.4% and 14.5%,respectively,when the subcooling degree is2.5 ?,5 ?,7 ? and 10 ? respectively.(4)By comparing the three systems,it is found that the system with parallelcompression and the mechanical supercooling system have improved COP under the same working conditions compared with the basic booster system,and the COP of the mechanical supercooling system is higher than that of the parallel compression system.In the calculated operating range,the maximum COP with parallel compression is 7.8% higher than the maximum COP of the basic booster system;the maximum COP of the system with subcooling at 5? is greater than the basic booster system 30.7%;the maximum COP of the system with a subcooling degree of 10 ?is 38.2% higher than the maximum COP of the basic booster system.And compared to the basic booster system,the other two systems' the optimal gas cooler pressure is lower.(5)By the theoretical analysis and selection calculation,the basic booster system test bed was set up.