Two-phase non-equilibrium models: the challenge of improving phase change heat transfer prediction



Título del documento: Two-phase non-equilibrium models: the challenge of improving phase change heat transfer prediction
Revista: Journal of the Brazilian Society of Mechanical Sciences and Engineering
Base de datos: PERIÓDICA
Número de sistema: 000312291
ISSN: 1678-5878
Autores: 1
Instituciones: 1Universidade Federal de Santa Catarina, Departamento de Engenharia Mecanica, Florianopolis, Santa Catarina. Brasil
Año:
Periodo: Ene-Mar
Volumen: 27
Número: 1
Paginación: 31-45
País: Brasil
Idioma: Inglés
Tipo de documento: Artículo
Enfoque: Experimental
Resumen en inglés This lecture addresses some recent developments in modelling of macroscopic thermodynamic and hydrodynamic non-equilibrium phenomena in convective phase change (boiling and condensation) of pure fluids and mixtures. Proper accounting of such phenomena may hold the key to explain and predict deviations from the classical (equilibrium) phase change convective heat transfer behaviour reported in the literature and yet not fully understood. In the first part of the paper, a detailed qualitative description of the classical heat transfer coefficient behaviour is presented together with two examples of departure from macroscopic equilibrium largely supported by experimental evidence. The second part of the paper reviews successful attempts to model the non-equilibrium phase change phenomena taking place in the two situations. The first example is a thermodynamic non-equilibrium slug flow model (one in which saturated Taylor bubbles become separated by slugs of subcooled liquid) that predicts the peaks in heat transfer coefficient at near-zero thermodynamic quality observed in forced convective boiling of some pure liquids. The occurrence of such peaks is typical of low latent heat, low thermal conductivity systems and of systems in which the vapour volume formation rate for a given heat flux is large. The second example is a comprehensive annular flow calculation methodology that predicts the decrease in the heat transfer coefficient with increasing quality observed in convective boiling of binary and multicomponent mixtures. In this cas
Disciplinas: Ingeniería
Palabras clave: Termodinámica,
Hidrodinámica,
Fluidos,
Flujo,
Cambio de fase
Keyword: Engineering,
Thermodynamics,
Phase change,
Hydrodynamics,
Flow,
Fluids
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