PHASE CHANGE HEAT TRANSFER – A PERSPECTIVE FOR THE FUTURE

Abstract

During the last half of the twentieth century, significant advances have been made in developing an understanding of phase change heat transfer (e.g., boiling and condensation). Further advances in phase change heat transfer will continue to take place motivated by new technologies such as microelectronics, thermal management in space, advanced terrestrial and space power systems and processing of designed materials. In the past, because of the complexity of the processes, very often we have “oversimplified”, maybe out of necessity, the modeling of the processes. The resulting weaknesses in our models and correlations have continued to haunt us whenever we have encountered new applications. In order to address the phenomena from basic principles, in my opinion, we need to pay attention to processes occurring at nano to micro to macro scales, capitalizing on recent advances that have been made in experimental and numerical techniques. These phenomena include nucleation, evolution, merger and breakup of vaporliquid interfaces, contact line behavior; coupling of the bulk and surface features of the solid; and the role of nano and micro inhomogeneties and intermolecular forces between solid and liquid. Prediction of nucleate boiling transfer is taken as an example to demonstrate the value of coupling different scales in meeting the overall objective.