Role of a condenser in a steam power plant: Which of the following effects are achieved by employing a surface condenser in the Rankine cycle?

Introduction / Context:
Condensers are integral to modern steam power plants. By condensing exhaust steam, they influence thermodynamic performance and facilitate feedwater recovery. Understanding their multiple simultaneous effects is crucial for Rankine cycle analysis.

Given Data / Assumptions:

• Surface condenser operating under vacuum.
• Exhaust steam from turbine or engine enters the condenser.
• Cooling water removes latent heat, converting steam to water.

Concept / Approach:
Condensation reduces the exhaust pressure (back pressure) below atmospheric, thereby increasing the pressure ratio across the turbine/engine and the overall expansion ratio. At the same time, it lowers the temperature of the exhaust steam to near the saturation temperature at condenser pressure and returns condensate for reuse, improving cycle efficiency and reducing makeup water needs.

Step-by-Step Solution:
Condenser action: condense exhaust → create vacuum → lower p_back.Lower p_back increases expansion from boiler pressure to condenser pressure → higher specific work output.Heat rejection to cooling water reduces exhaust steam temperature during phase change.Collectively, these are described by the option “all of these”.

Verification / Alternative check:
Rankine T–s and p–v diagrams show increased area (work) when condenser pressure drops; condenser outlet condensate temperature matches saturation at vacuum pressure.

Why Other Options Are Wrong:
Any single effect description is incomplete; the condenser simultaneously reduces back pressure, increases expansion ratio, and reduces exhaust temperature. It does not directly raise boiler pressure (that is a function of boiler and control systems).

Common Pitfalls:
Attributing increases in boiler pressure to condenser performance; overlooking cooling water constraints and air removal for maintaining vacuum.

Final Answer:
all of these