The acceleration of investigation into droplet flows, which play an important role in weather formation (clouds, rain) and are the basis of industrial technologies, is supported by the implementation of new tools and enhancement in theory. The analysis of energy transport considers both large-scale energy transfer mechanisms (with flow and waves) and fine mechanisms (dissipative and conversion). Integrated experimental techniques combine photographic and video recording of flows with multipoint illumination, and quick computer data processing. The merging drop can react chemically with a transparent target fluid. High-resolution observations have allowed us to identify several modes of coalescing droplet flow: intrusive, transition, and impact. The list of components of drop flows including a cavity, crown, spikes, sprays, splashes, packets of capillary and acoustic waves, is supplemented by ligaments, i.e. fine jets whose wakes form expressive linear and reticular structures. In the impact mode, the jets flow along the walls of the cavity and crown, creating spikes with droplets on the veil edge. Other groups of jets pierce the cavity bottom and create an intermediate layer. The geometry of the domains where chemical reactions occur in droplet flows was traced. The mechanisms for the contact surface continuity disrupting at different stages of flow evolution are discussed. These mechanisms include the surface energy conversion during the initial drop contact with the target fluid and the inertial mechanism at a stage of primary fibers and loops in the liquid thickness below the collapsing cavity.