Steam enters a turbine steadily at 4 MPa and 600^∘ C and exits at 0.2 MPa and 150^∘ C in an envi

step 1 Hi friend, the exergy decrease is defined as H1 minus H2 minus T0 S1 minus S2. That is 367, 3674

Steam enters a turbine steadily at 4 MPa and 600^∘ C and...

Steam enters a turbine steadily at $4 \mathrm{MPa}$ and $600^{\circ} \mathrm{C}$ and exits at $0.2 \mathrm{MPa}$ and $150^{\circ} \mathrm{C}$ in an environment at $25^{\circ} \mathrm{C}$ The decrease in the exergy of the steam as it flows through the turbine is (a) $879 \mathrm{~kJ} / \mathrm{kg}$ (b) $1123 \mathrm{~kJ} / \mathrm{kg}$ (c) $1645 \mathrm{~kJ} / \mathrm{kg}$ (d) $1910 \mathrm{~kJ} / \mathrm{kg}$ (e) $4260 \mathrm{~kJ} / \mathrm{kg}$

Steam enters a turbine steadily at $4 \mathrm{MPa}$ and $600^{\circ} \mathrm{C}$ and exits at $0.2 \mathrm{MPa}$ and $150^{\circ} \mathrm{C}$ in an environment at $25^{\circ} \mathrm{C}$ The decrease in the exergy of the steam as it flows through the turbine is
(a) $879 \mathrm{~kJ} / \mathrm{kg}$
(b) $1123 \mathrm{~kJ} / \mathrm{kg}$
(c) $1645 \mathrm{~kJ} / \mathrm{kg}$
(d) $1910 \mathrm{~kJ} / \mathrm{kg}$
(e) $4260 \mathrm{~kJ} / \mathrm{kg}$

Key Concepts

Exergy

Exergy is a measure of the maximum useful work that can be extracted from a system as it reaches thermodynamic equilibrium with its surroundings. It accounts for the quality or usability of energy and is a central concept when analyzing how energy degrades due to irreversibilities in a process.

Irreversibility

Irreversibility refers to the losses encountered in any real process, where the available work potential is destroyed due to factors such as friction, heat transfer across finite temperature differences, or other non-ideal behavior. In turbine analysis, these irreversibilities are quantified as a decrease in exergy.

Second Law of Thermodynamics

The second law of thermodynamics deals with the direction of energy transformations and establishes that not all energy can be converted into useful work due to entropy generation. Exergy analysis is built on the second law by identifying and quantifying the portion of energy that remains available to do work.

Thermodynamic Properties

Thermodynamic properties such as pressure, temperature, enthalpy, and entropy are used to characterize the state of a substance. These properties are essential for calculating both energy and exergy balances in processes like steam expansion through a turbine.

Dead State

The dead state is the concept of a reference environment, usually defined by ambient conditions (temperature and pressure), where the system is in equilibrium with its surroundings and possesses zero exergy. It forms the baseline for determining how much exergy (or work potential) is lost in a process.

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