What happens to cycle efficiency if condensate depression is reduced?

What happens to cycle efficiency if condensate depression is reduced?

• A. Less heat energy is rejected to circulating water system, increasing efficiency
• B. More heat energy is rejected
• C. No change
• D. Condensate depression increases efficiency only

Answer: (A)

Condensate depression controls how much heat must be dumped to the cooling system through the condenser. When this depression is reduced, the condensate returns at a higher pressure, which raises the condenser pressure and the condensing temperature. The higher condensing temperature reduces the driving temperature difference between the steam and the circulating water, so less heat is transferred to the circulating water for the same amount of steam. With less heat being rejected, more of the input heat stays in the cycle to produce work, so the cycle efficiency increases. In short, reducing condensate depression lowers the heat rejected to the cooling system, improving overall efficiency.

Condensate depression controls how much heat must be dumped to the cooling system through the condenser. When this depression is reduced, the condensate returns at a higher pressure, which raises the condenser pressure and the condensing temperature. The higher condensing temperature reduces the driving temperature difference between the steam and the circulating water, so less heat is transferred to the circulating water for the same amount of steam. With less heat being rejected, more of the input heat stays in the cycle to produce work, so the cycle efficiency increases. In short, reducing condensate depression lowers the heat rejected to the cooling system, improving overall efficiency.