Maybe I'm over-analysing this but if we take a simple example of a tube within which steam is flowing. Why does the temperature (and pressure) of the steam increase as the mass flow rate is increased? Is it simply because as more mass is added in the flow, the pressure within the system increases and as a result, the saturation temperature must also increase? Or is the addition of thermal mass and the higher kinetic energy associated with it responsible in some way for the temperature increase? I feel I'm over-thinking a straighforward concept but hopefully someone can clarify this. All views are appreciated! Cheers.