Non-Condensing Steam Engine — Exhaust Pressure In a non-condensing steam engine (exhaust to atmosphere), the pressure of steam in the cylinder during the exhaust stroke is __________ the condenser pressure.

Introduction / Context:
The back pressure during exhaust strongly influences engine work output. Non-condensing engines discharge directly to atmosphere, while condensing engines discharge into a vacuum created by the condenser. Comparing these pressures helps explain efficiency differences.

Given Data / Assumptions:

• Non-condensing operation: exhaust opens to atmospheric conditions.
• Condensing operation: condenser maintains sub-atmospheric pressure (vacuum).
• Neglect small pressure drops in exhaust passages for the conceptual comparison.

Concept / Approach:
Atmospheric pressure is much higher than the condenser (vacuum) pressure. Therefore, during exhaust in a non-condensing engine the cylinder pressure remains close to atmospheric and is necessarily higher than the condenser pressure that would exist in a condensing engine. This higher back pressure reduces the net work per cycle.

Step-by-Step Solution:
Identify reference pressures: p_atm vs p_cond (vacuum).During exhaust to atmosphere: cylinder pressure ≈ p_atm.Since p_atm > p_cond, conclude p_exhaust (non-condensing) is higher than condenser pressure.

Verification / Alternative check:
Indicator diagrams show a higher exhaust line for non-condensing engines compared to condensing ones, reducing loop area.

Why Other Options Are Wrong:
equal to / lower than: contradicts the fundamental difference between atmospheric exhaust and condenser vacuum.

Common Pitfalls:
Confusing absolute and gauge pressures; the comparison is on absolute pressure scale.

Final Answer:
higher than