A Transient Nucleate Boiling Model Including Microscale Effects and Wall Heat Transfer

Abstract

A new model is presented to compute nucleate boiling heat and mass transfer. It is based on a previous one (Kern, J., and Stephan, P., 2003, ASME J. Heat Transfer, 125, pp. 1106–1115) for quasi-stationary heat transfer to single vapor bubbles. In contrast to the preceding model, fully transient heat and fluid flow is computed with a free surface of the rising bubble and a periodic calculation of repeated cycles of bubble growth, detachment, and rise, requiring only specification of the waiting time between successive bubbles. Additionally, microscopic effects at the foot of the bubble are considered. The model is verified by comparing computed with measured heat transfer coefficients. Typical results for heat and mass transfer to a single vapor bubble are shown at all time steps of the bubble cycle. By means of the model the transient heat flow through different interfaces, e.g., wall/liquid or liquid/vapor, is computed for the whole bubble cycle. Thus, it was possible to evaluate the influence of transient heat conduction, heat storage, and convection in liquid as well as heat transfer in the wall on overall heat transfer performance.

Boiling Heat Transfer: Mechanisms, Models, Correlations and the Lines of Further Research

“…Principal disadvantage of microlayer evaporation version of MTA is connected with contradiction between independence of HTC on thermal parameters of heating surface during developed boiling and aforementioned conclusion about significant influence of thermal conductivity of heating surface on average HTC during microlayer evaporation (by the way, this conclusion is supported by numerical MTA-based models of boiling heat transfer [70,73]) developed based at assumption on leading role of micro and macrolayer evaporation mechanisms.…”

“…Beginning from Jakob [6], Kruzhilin [58] and Rohsenow [59] and further [60][61][62][63][64][65][66][67][68][69][70][71][72][73] main line of development of boiling heat transfer theory is based at approaches connecting HTC to intensity of certain cooling mechanism (an actor) or certain combination of different cooling mechanisms (actors). In this connection these approaches are subsumed under the category dubbed as a model of "the theatre of actors" (MTA).…”

Experimental study of gas injected bubble growth from submerged orifices

“…At the triple contact line, the contact angle is dynamic and differs from the static contact angle which also plays a part in determining the bubble dynamics [34]. In this respect, mechanistic-based or numerical models which oversimplify the bubble geometry, such as assuming a constant apparent contact angle [35,36] or assuming that the bubble remains a section of a sphere [37,38] can, in many instances, not be representative of the actual physical phenomena since the Laplace pressure drop is sensitive to bubble shape [34].…”

Interferometric Measurement of the Liquid-Phase Temperature Field around an Isolated Boiling Bubble

“…While the contribution of the liquid-phase heat transfer has been evaluated by various analytical methods [11,12] and numerical simulations [13,14], we believe that there is no study that approaches it experimentally. Therefore, we have attempted to observe the temperature field around a boiling bubble by interferometry to directly measure the evaporative heat transfer from the liquid phase.…”