A brief overview is presented of the principal areas where thermal plasmas had a significant technological impact over the past century. This is followed by an analysis of the specific role played by modelling and studies of transport phenomena under plasma conditions for three specific examples. The first dealing with the development of inductively coupled plasma sources. The following two examples deals with process development for the in-flight melting and spheroidization of powders, and the synthesis of nano-powders. Emphasis is placed on the critical role of plasma-particle interactions under dense loading conditions. A proposal is made for a relatively simple thermodynamic model which can be used for the estimation of the theoretical limits for the processing rates possible with different powders in each of these two cases. The model takes into account radiative energy losses from the surface of the particles and from the formed vapor cloud in the plasma, as well as the residual energy in the gases at the exit of the plasma reactor which are not accessible for process needs.