Entropy Balance in Closed Systems and Processes

Entropy Balance

Conservation of entropy in a closed system.

Clausius Inequality

Entropy change is less than or equal to heat transfer.

Entropy Transfer

Entropy change due to heat transfer, Q > 0.

Entropy Production

Generated entropy due to irreversibility, σ.

Path Function

Value depends on process, not state.

Second Law of Thermodynamics

Entropy of an isolated system never decreases.

Integral Term

Represents total entropy change in a process.

Uniform Temperature

Constant temperature at system boundary during heat transfer.

Differential Form

Rate of change of entropy in a system.

Rate Form

Entropy change per unit time in a system.

Principle of Entropy Increase

Processes increase total entropy of system and surroundings.

Statistical Thermodynamics

Relates entropy to disorder at a microscopic level.

Control Volume

A fixed region in space for analyzing flow.

Reynolds Transport Theorem

Links system and control volume analysis.

Heat Flux

Rate of heat transfer per unit area.

Isentropic Process

Process with constant entropy, no heat transfer.

Isentropic Efficiency

Ratio of actual work to ideal work in turbines.

Polytropic Process

Process where pressure and volume are related by n.

Ideal Gas

Gas that follows the ideal gas law, PV=nRT.

Specific Entropy Change

Change in entropy per unit mass.

Steady-State Operation

Conditions where properties remain constant over time.

Adiabatic Process

No heat transfer occurs during the process.

Entropy Rate Balance

Balance of entropy entering and leaving a control volume.

Heat Transfer Rate

Rate at which heat is added or removed.

Work Done Rate

Rate at which work is performed in a system.

Inlet and Exit States

Conditions at the entry and exit of a system.

Non-Dimensional Variables

Variables scaled to remove units for comparison.

Relative Pressure

Pressure compared to a reference pressure.

Relative Volume

Volume compared to a reference volume.