Microfluidic flows are physically diverse as they can be associated with free surface motion evolving as falling films, spreading and de-wetting of liquids on solid or liquid substrates, chemical reaction of binary mixtures, microbubbles and droplet motion, phase change or transition. The control of micro-flow systems (using pressure, Marangoni, electro-wetting or acoustics) is central to future technological advances in emerging technologies. Modern CMFD (CFD relying on interface tracking) has proven to be highly effective in predicting small-scale multi-phase flows and can provide virtual information about intricate flow details, regardless of system size, which are otherwise impossible to detect (in time or space) using available visualisation technologies. Here we will discuss several examples of droplet dynamics and heat transfer: from microfluidics and MedTech applications to large-scale energy systems.