Thermodynamic analysis of transcritical CO2 refrigeration cycle integrated with absorption refrigeration system and ejector

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Thermodynamic analysis of transcritical CO2 refrigeration cycle integrated with absorption refrigeration system and ejector

ارائه دهنده: Provider: mahsa heydareh

اساتید راهنما: Supervisors: Dr. Fazlallah Eskandari Manjili (Ph.D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. mohsen godarzi, Dr. mohammad saeed aghighi

زمان و تاریخ ارائه: Time and date of presentation: 2022/09/20, 11 am

مکان ارائه: Place of presentation: seminar of two departments of mechanics

چکیده: Abstract: Climate change caused by the emission of greenhouse gas is a serious global problem, and the significant impact of the refrigeration and air conditioning industry in reducing the thickness of the ozone layer and global warming, which is mainly attributed to the widespread use of atrifical refrigerants has become an alarming issue. Therefore, the interest in natural refrigerants is increasing rapidly, and in this situation, environmentally friendly natural refrigerant CO2 has received much attention. But due to the low critical temperature of CO2, this system must be operated with a transcritical cycle mode, and on the oyher hand, the coefficient of performance of the transcritical CO2 cycle is often lower than conventional systems with artificial refrigerants. For this reason, in order to improve the performance of the system, some strategies have been considered such as the use of ejector, interal heat exchanger, mechanical subcoolers, thermoelectric subcoolers and …, but still efforts are made to reduce the energy consumption of heating and cooling devices is one of the important and practical topics. Therefore, in this project, absorption system is used as additional cooling in the cycle without consuming energy and improve the performance of the cycle. Then, the obtained results are compared with the results of a study on a combined cycle with thermoelectric subcooler and ejector, and the effects of important operating parameters on the system performance are investigated with energy and exergy analysis. The first chapter examines the importance of the refrigeration system, the important parameters in this process and the literatyre on the subject. In the second chapter of the study of CO2 refrigeration cycle, absorption refrigeration cycle, combined cycles and the relationships required for the mentioned cycles have been extracted. In the third chapter, the thermodynamic modeling og the mentioned cycle is discussed for validation, and the results obtained from the simulation of the proposed cycle and its comparison with the existing similar cycles are presented. The discussion and investigatin is done in the fourth chapter and the conclusion and suggestions are presented at the end. The obtained results show that compared to the combined cycle with thermoelectric subcooler , the system work is reduced by 7.5% and COP and exergy efficiency also 7.53% and 10.5% respectively increased, but it should be noted that this amount of improvement is mentioned for the optimum point of the combined cycle with thermoelectric subcooler ,and for a larger subcool the difference is much larger.

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