The area enclosed by the cycle on a T-s diagram represents the net heat transfer (Q₁ – Q₂), which equals the net work done (W) for a closed cycle, per the first law. However, in the context of T-s diagrams, it is typically interpreted as the net heat transfer

The h-s (Mollier) diagram is commonly used to determine the quality of steam, as it shows the saturated liquid and vapor lines, with constant quality lines plotted in the wet region, allowing direct reading of the dryness fraction.

An isenthalpic process (constant enthalpy) in a vapor compression cycle, such as throttling, does not directly appear on a T-s diagram as constant enthalpy. However, for simplicity in GATE questions, it’s often approximated as a horizontal line due to minimal temperature change in some cases, though strictly it’s a complex path. (Note: On an h-s diagram, it would be vertical.)

 For a polytropic process with n ≠ 1, the temperature and entropy both change, resulting in a curved path on the T-s diagram, determined by the relation T Vⁿ⁻¹ = constant.

For an isentropic process on an h-s diagram, the work output of the turbine is the enthalpy difference (Δh), which corresponds to the vertical distance between the initial and final states.

Isentropic expansion in the turbine is a constant-entropy process, represented by a vertical line on the T-s diagram, as entropy (s) remains constant while temperature (T) decreases.

On an h-s diagram, constant pressure lines diverge as entropy increases, indicating that for a given pressure, enthalpy (h) increases with entropy (s) in the superheated vapor region

 From the thermodynamic relation T dS = δQ for a reversible process, the area under a curve on a T-s diagram represents the heat transfer (Q) during the process.

 For an isothermal process, temperature (T) is constant. On a T-s diagram, this is represented by a horizontal line, as entropy (s) changes while T remains constant.

 A reversible adiabatic process is isentropic (constant entropy), so it appears as a vertical line on a T-s diagram, where entropy (s) remains constant.