What's meaning of pressure drop for fluid?
 

I need calculation the pressure drop of heat exchanger(shell fluid pressure drop),however I don't know what's the meaning of pressure drop? is it the inlet total pressure minus outlet total pressure? or inlet static pressure minus outlet static pressure? or hydraulic loss times dynamic pressure? please help me.

The basic definition of pressure drop for a heat exchanger is Inlet Total Pressure minus Outlet Total Pressure. This pressure drop is characterized as due to a sort of frictional resistance, and therefore a nondimensional Hydraulic Loss Coefficient or Friction Coefficient is defined as the pressure drop divided by the dynamic pressure. The dynamic pressure is chosen as the reference, because actual viscous losses are a function of the dynamic pressure.