Meaning of Entropy Increase – What Does It Signify? An increase in the entropy of a system (or universe) represents degradation of energy quality and a reduction in the maximum useful work (availability/exergy) obtainable.

Introduction / Context:
Entropy is a measure of energy dispersion and irreversibility. When entropy increases, less of the system's energy can be converted into useful work. Understanding this connection is vital in power-plant, refrigeration, and process design.

Given Data / Assumptions:

• Second-law framework with system and surroundings.
• Availability/exergy defined relative to an environment state.
• Irreversibilities generate entropy and destroy exergy.

Concept / Approach:

Entropy generation S_gen > 0 accompanies friction, mixing, unrestrained expansion, finite-ΔT heat transfer, and chemical irreversibility. Exergy destruction is T0 * S_gen (per unit time or process), where T0 is ambient temperature. Thus, higher entropy implies lower capacity to do work, i.e., degraded energy quality.

Step-by-Step Solution:

Verification / Alternative check:

Turbine with high irreversibility yields larger S_gen and lower actual work versus isentropic ideal; heat exchanger with large temperature differences generates entropy and reduces potential to do work.

Why Other Options Are Wrong:

Availability does not increase with entropy; temperature/pressure changes are not direct indicators of entropy sign; potential energy is unrelated to entropy definition.

Common Pitfalls:

Equating entropy strictly with 'disorder' without linking to work potential; assuming any temperature rise means entropy rise (not necessarily true).

Final Answer:

degradation of energy