每年出版 4 期
ISSN 打印: 0276-1459
ISSN 在线: 1943-6181
Indexed in
FLOW REGIME BASED MODELLING OF TWO-PHASE HEAT TRANSFER
摘要
Old-style models for evaporation (and condensation) ignore flow regime effects on heat transfer, concentrating only on the heat transfer mechanisms involved. This approach greatly limits their range of validity and reliability, resulting in prediction errors often surpassing 100% at typical design conditions. In the past few years, general thermal design methods have begun to emerge that are based on local two-phase flow patterns and the flow structure of the two-phases. In fact, the current trend is towards a completely global approach, that is one that provides a unified model of two-phase heat transfer, two-phase flow patterns (and prediction of their transitions as a map), void fraction and two-phase pressure drops. Thus, a new paradigm for modelling of two-phase flow and heat transfer is emerging in which there is no more justification for proposing new two-phase heat transfer correlations that are blind with respect to flow regime. The status of these new developments is discussed with particular emphasis on intube evaporation where most of the progress has been made, but shell-side boiling, falling film evaporation, intube condensation and two-phase pressure drops are also addressed.