Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Characterization of Vapor Compression Refrigeration Cycles through the Second Law of Thermodynamics
Submission Author:
Vinicius Akyo Matsuda , MG
Co-Authors:
Vinicius Akyo Matsuda, Luben Cabezas Gómez, Álvaro Gardenghi
Presenter: Vinicius Akyo Matsuda
doi://10.26678/ABCM.COBEM2021.COB2021-0604
Abstract
In this work a transient behavior of a dual-skin chest freezer refrigeration system, operating with R290, is studied numerically with the purpose of performing the characterization of the system through the Second Law of Thermodynamics. For this aim a mathematical model which accounts for mass distribution inside the system is used. More specifically this work addresses the calculation of entropy generation and exergy destruction for characterizing the system behavior in the pull-down and on-off operations. In order to validate the model a comparison with measured experimental data is performed. In the pull-down operation the mathematical model is evaluated for the system transient and steady-state regimes. The on-off operation is also modeled, allowing the comparison of the results given by the proposed model with the experimental data during system's transients, including when the compressor is turned down. The characterization of the system through the second law of Thermodynamics is conducted using two different methods. One consists in a direct calculation of the entropy generation rate and the other in the calculation of exergy destruction rate. The equivalence of these two methods is used as an indicative of the “correctness” of the performed calculations. The second Law system efficiency is also estimated in the studied vapor compression cycle operational conditions. The obtained results are well behaved in relation to the experimental data used in the comparisons. The system's characterization with the second law results indicates the transient behavior of entropy generation and exergy destruction with time in the whole system and in its components. These results are useful for improving the refrigeration system design.
Keywords
Transient numerical simulation, Second Law of Thermodynamics, Vapor Compression Cycle, Efficiency, R290
