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Type: Tese de Doutorado
Title: Theoretical and experimental studies on boiling heat transfer for the zeotropic mixture R-407C
Authors: Matheus Pereira Porto
First Advisor: Luiz Machado
First Co-advisor: Carlos F. M. Coimbra
First Referee: Ricardo Nicolau Nassar Koury
Second Referee: Antonio Augusto Torres Maia
Third Referee: Carlos Umberto da Silva Lima
metadata.dc.contributor.referee4: Antônio Carlos Lopes da Costa
Abstract: This work concerns theorical and experimental methods for understanding the heat transfer mechanisms for a zeotropic fluid, namely R-407C. The refrigerant R-407C is a mixture of three refrigerants, R-134a, R-32, and R-125, which may replace R-22 in future refrigerant systems. Due to the degradation of heat transfer coefficients in mixtures such as R-407C, the classical relations may overestimate the experimental heat transfer rates. A correction based on nucleate boiling suppression factors that corrects a previously proposed relation is used to minimize the degradation error. The newly proposed relation was developed through a robust methodology based on genetic algorithm (GA) optimization for three additional refrigerants R-404a, R134a and R-22. A discussion about inventory is also presented, where a modified Otaki method is proposed for the more realistic scenario that corresponds of not knowing a priori the heat transfer coefficient. The inventory obtained by the modified Otaki method is higher than the one obtained by the traditional Otaki method. Both methods yield accurate results for R-407C.
Subject: Engenharia mecânica
language: Português
Publisher: Universidade Federal de Minas Gerais
Publisher Initials: UFMG
Rights: Acesso Aberto
Issue Date: 13-Sep-2013
Appears in Collections:Teses de Doutorado

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