Fundamental data on the gas–liquid two-phase flow in minichannels ☆ ☆ A preliminary version of this paper was presented at ICMMO5: Third International Conference on Microchannels and Minichannels, held at University of Toronto, June 13–15, 2005, organized by S.G. Kandlikar and M. Kawaji, CD-ROM Proceedings, ISBN: 0-7918-3758-0, ASME, New York.