Condenser performance term: selecting the correct definition The ratio defined as: (temperature rise of cooling water) / (vacuum-temperature corresponding to condenser pressure minus the inlet cooling-water temperature) is termed:

Introduction / Context:
Surface condensers cool exhaust steam by transferring heat to circulating water. To evaluate performance, engineers use a non-dimensional efficiency comparing actual water temperature rise to the maximum theoretically attainable rise for the given terminal temperatures.

Given Data / Assumptions:

• T_out and T_in are outlet and inlet temperatures of cooling water.
• T_sat is the saturation (vacuum) temperature corresponding to condenser pressure.
• Steady operation with negligible heat leaks except to cooling water.

Concept / Approach:
Condenser efficiency, η_cond, is commonly expressed as (T_out − T_in) / (T_sat − T_in). The denominator is the maximum possible rise if the water could approach the steam saturation temperature at the hot end. The actual rise divided by this maximum gives a convenient performance index between 0 and 1 (or 0–100%).

Step-by-Step Solution:
Identify numerator: temperature gain of water = T_out − T_in.Identify denominator: T_sat − T_in (vacuum temperature minus inlet water temperature).Form the ratio: η_cond = (T_out − T_in) / (T_sat − T_in).Match with the name: condenser efficiency.

Verification / Alternative check:
Used alongside “vacuum efficiency” and “air removal effectiveness,” this definition appears in standard thermal engineering texts and condenser test procedures.

Why Other Options Are Wrong:
Vacuum efficiency relates to how closely the measured vacuum approaches the ideal based on air leakage; nozzle and boiler efficiency are unrelated; “air cooler effectiveness” is not standard in this context.

Common Pitfalls:
Confusing T_sat with measured shell temperature; using gauge vacuum directly as temperature without conversion to saturation temperature.

Final Answer:
condenser efficiency