What is the primary function of the diffuser in a centrifugal compressor?

What is the primary function of the diffuser in a centrifugal compressor?

• A. Increases temperature
• B. Converts velocity into pressure rise
• C. Increases velocity
• D. Lubricates

Answer: (B)

The diffuser’s job is to recover the velocity energy of the flow as static pressure. After the impeller boosts the gas velocity, the diffuser uses its gradually expanding passage to slow the gas down. As velocity decreases, static pressure rises, delivering a higher-pressure, lower-velocity stream to the next stage or to discharge. This pressure-raising function is why it’s the primary role. It doesn’t primarily heat the gas, it doesn’t increase velocity, and it doesn’t perform lubrication.

The diffuser’s job is to recover the velocity energy of the flow as static pressure. After the impeller boosts the gas velocity, the diffuser uses its gradually expanding passage to slow the gas down. As velocity decreases, static pressure rises, delivering a higher-pressure, lower-velocity stream to the next stage or to discharge. This pressure-raising function is why it’s the primary role. It doesn’t primarily heat the gas, it doesn’t increase velocity, and it doesn’t perform lubrication.