Purpose of a surface condenser in Rankine cycle plants: “A condenser maintains a pressure below atmospheric to extract maximum energy from steam and thereby improve efficiency.” State whether this statement is correct.

Introduction / Context:
Condensing is a central feature of efficient Rankine cycle operation in power plants. By reducing the exhaust (back) pressure, the turbine or engine can expand steam through a higher pressure ratio, extracting more specific work from each kilogram of steam.

Given Data / Assumptions:

• Surface condenser operated with cooling water, air extraction, and vacuum maintenance.
• Boiler pressure remains fixed by boiler/turbine settings; condenser affects the low-pressure end.
• Steady-state operation with adequate heat rejection capacity.

Concept / Approach:
Lowering back pressure increases the expansion ratio and the area under the expansion curve on p–v or T–s diagrams, which corresponds to higher work output per unit mass of steam. The condenser converts exhaust steam to condensate at low pressure and temperature, enabling feedwater recovery and improved cycle efficiency.

Step-by-Step Solution:
Identify objective: maximize specific work by extending expansion to low pressure.Condenser action: condense exhaust, remove latent heat, and create vacuum below atmospheric pressure.Effect on cycle: increased pressure ratio → higher work and thermal efficiency.Conclusion: the statement is correct.

Verification / Alternative check:
Comparing Rankine cycle efficiencies at p_cond = 0.1 bar vs 1.0 bar shows significant efficiency increase at lower condenser pressure.

Why Other Options Are Wrong:
“Disagree” and conditional variants contradict standard Rankine analysis; condenser action does not raise boiler pressure; it reduces exhaust pressure.

Common Pitfalls:
Attributing efficiency increase to boiler pressure alone; neglecting the role of air removal and cooling-water temperature in maintaining condenser vacuum.

Final Answer:
Agree