| Journal: | Journal of the Brazilian Society of Mechanical Sciences and Engineering |
| Database: | PERIÓDICA |
| System number: | 000312291 |
| ISSN: | 1678-5878 |
| Authors: | Barbosa-Junior, J.R1 |
| Institutions: | 1Universidade Federal de Santa Catarina, Departamento de Engenharia Mecanica, Florianopolis, Santa Catarina. Brasil |
| Year: | 2005 |
| Season: | Ene-Mar |
| Volumen: | 27 |
| Number: | 1 |
| Pages: | 31-45 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Experimental |
| English abstract | 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 |
| Disciplines: | Ingeniería |
| Keyword: | Termodinámica, Hidrodinámica, Fluidos, Flujo, Cambio de fase |
| Keyword: | Engineering, Thermodynamics, Phase change, Hydrodynamics, Flow, Fluids |
| Full text: | Texto completo (Ver PDF) |
