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RISS 인기검색어
- 검색키워드
- 저자 : Ierin Volodymyr (검색결과 2 건)
- 무료
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Thermodynamic analysis of hybrid two-stage CO2 mechanical compression–ejector cooling cycle
Ierin Volodymyr,Chen Guangming,Hao Xinyue,Volovyk Oleksii 대한설비공학회 2023 International Journal of Air-Conditioning and Refr Vol.31 No.1
In the present study, the main results of thermodynamic analysis of the hybrid two-stage carbon dioxide (CO2) transcritical mechanical compression–ejector cooling cycle using R245ca are provided. In the proposed cycle, an increase in the energy efficiency of a mechanical compression refrigeration machine (MCRM) is provided by additional supercooling of CO2 after the gas cooler due to the use of cold obtained in an ejector cooling machine (ECM). The ECM uses part of the superheated vapor heat after the high-pressure compressor and the intermediate pressure heat after the low-pressure compressor. This solution provides intermediate cooling of CO2 vapor without using an external cooling medium. The proposed method of computation makes it possible to determine the optimal parameters of the hybrid cooling cycle for the design conditions, ensuring the maximum possible MCRM efficiency. At the same time, the method considers the need to determine the optimal gas cooler pressure – a parameter that has a significant impact on efficiency growth. The effect of the intermediate pressure is extremely insignificant and is defined as the geometric mean value of the product of the gas cooler and evaporator pressures. The results show an increase in efficiency of the two-stage CO2 MCRM by up to 31.6% at high temperatures of the environment. In addition, as a result of the exergy analysis, components have been identified, the improvement of which can lead to an additional increase in the efficiency of the entire system. As follows from the data obtained, the greatest attention should be paid to improving the ejector and reducing throttle losses in the CO2 cycle. In the present study, the main results of thermodynamic analysis of the hybrid two-stage carbon dioxide (CO 2 ) transcritical mechanical compression–ejector cooling cycle using R245ca are provided. In the proposed cycle, an increase in the energy efficiency of a mechanical compression refrigeration machine (MCRM) is provided by additional supercooling of CO 2 after the gas cooler due to the use of cold obtained in an ejector cooling machine (ECM). The ECM uses part of the superheated vapor heat after the high-pressure compressor and the intermediate pressure heat after the low-pressure compressor. This solution provides intermediate cooling of CO 2 vapor without using an external cooling medium. The proposed method of computation makes it possible to determine the optimal parameters of the hybrid cooling cycle for the design conditions, ensuring the maximum possible MCRM efficiency. At the same time, the method considers the need to determine the optimal gas cooler pressure – a parameter that has a significant impact on efficiency growth. The effect of the intermediate pressure is extremely insignificant and is defined as the geometric mean value of the product of the gas cooler and evaporator pressures. The results show an increase in efficiency of the two-stage CO 2 MCRM by up to 31.6% at high temperatures of the environment. In addition, as a result of the exergy analysis, components have been identified, the improvement of which can lead to an additional increase in the efficiency of the entire system. As follows from the data obtained, the greatest attention should be paid to improving the ejector and reducing throttle losses in the CO 2 cycle.
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Morozyuk Larisa,Sokolovska-Yefymenko Viktoriia,Moshkatiuk Andrii,Ierin Volodymyr,Basov Anatolii 대한설비공학회 2023 International Journal of Air-Conditioning and Refr Vol.31 No.1
The paper presents the results of a theoretical and experimental study aimed at improving the efficiency of commercial refrigeration systems and taking into account the external negative impact on heat transfer and aerodynamics of an air-cooled condenser. The issues of the impact of solid fouling on the outer heat transfer surface of the air-cooled condenser as a factor that worsens its energy efficiency and operational reliability have been studied. A small-scale commercial refrigeration machine has been used for carrying out the study. To create external real conditions in the experimental bench, a climatic chamber and a thermostatic chamber are provided. Three types of solid fouling have been used: dust, fluff, and sand. The fouling has been collected from real operating air-cooled condensers which are identical to the experimental heat exchanger. The experimental study has been carried out with a variable mass of fouling, which made it possible to simulate various real operating conditions for the air-cooled condenser. As a result of the experiment, it has been found that out of a set of fouling roadsides, the dust has the greatest negative impact on the characteristics of the refrigeration machine as a whole, and sand has the greatest negative effect on the internal characteristics of the air-cooled condenser. Recommendations are made to determine the moment of cleaning the surface of the air-cooled condenser based on energy-saving parameters. It is proposed to fix the moment of cleaning using computer software using the permissible air mass velocity as a key parameter and the refrigeration machine operation interval under this condition.
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