Tabooed Universal Characteristic Length and Misled Boiling Heat Transfer Research

Abstract

Abstract:The paper presents the next step within multiyear fruitless efforts of the author to overcome the absurd situation in boiling heat transfer research. The focus is made on the problem of the characteristic length of the process most clearly exhibiting the consequences of half a century ignoring the basic MTD (Model "theater of director"), the UC (Universal correlation) and some other boiling fundamentals. Echoing control of boiling heat transfer by nucleation, the MTD-UC identifies universal characteristic length, the AER (Average effective radius) of nucleation sites, equally workable at the macro-and microscale. Inefficiency of the generally accepted, so called MTA (theater of actors) is particularly pronounced just in the confusion with the characteristic length. Traditional and potential candidates, departure diameter of vapor bubble and transverse internal size of the channel hardly can be adjusted to independence of developed boiling HTC on mass acceleration, subcooling, liquid convection and the heating surface geometry. At the same time, even such a problem has not prevented many authors to develop tens or even hundreds of helpless MTA-based correlations. The ignoring the MTD-UC-AER has also led to the incompleteness of the standard boiling heat transfer experiment, which is usually done without studying nucleation sites (there are available only very few comprehensive experimental works including the data on the AER). The only exception was made for the problem of boiling heat transfer enhancement: over the past decades enhanced boiling surfaces were developed in direct accordance with the principle defined by the MTD-UC (just through the AER). Another thing is that the basic role of the MTD-UC-AER in substantial progress of the relevant R&D activities passed over in silence in the corresponding publications. Enviable unity and coherence of heat transfer community in preventing real scientific debate on the problem is also remarked.