# Specific total enthalpy VS Specific enthalpy

What is the difference between specific enthalpy and specific total enthalpy in the context of fluid flow?

## 1 Answer

Total enthalpy is defined as the static enthalpy (or "plain" enthalpy) plus the kinetic energy, i.e.:

$$h^\circ = h + \frac{v^2}{2}$$

In other words, the total enthalpy is the enthalpy that the fluid would have if it would be brought to halt by an adiabatic process (i.e. w/o heat transfer), thus converting the kinetic energy into enthalpy (pressure energy plus internal energy: the ratio among them is determined by the entropy production).

Such a conversion is actually happening in some real devices, e.g. at the exit of a final compressor stage, where kinetic energy is converted into pressure to avoid it being wasted due to turbulent dissipation.

• What exactly do you mean by arresting the flow? – user29463 Jul 18 at 15:30
• @user29463 I mean bring it to a halt. I've edited the answer in a hope it will be clearer. – El_Monto Jul 19 at 8:39