Where does stagnation pressure rise occur in a centrifugal compressor? Identify the component(s) responsible for the increase in total (stagnation) pressure.

Concept/Approach
The impeller does shaft work on the fluid, increasing total enthalpy and thus stagnation pressure (neglecting losses). The diffuser primarily converts kinetic energy to static pressure; ideally, total pressure would remain constant there (real diffusers have losses that can decrease stagnation pressure).

Conclusion
The rise in stagnation pressure is produced in the impeller.

Final Answer
In the impeller only.