Second Law of Thermodynamics
Work is said to be high-grade energy, and heat is low-grade energy. The complete conversion of low-grade energy into high-grade energy in a cycle is impossible, while the complete conversion of high-grade energy into low-grade energy is possible.
Second Law of Thermodynamics
Kelvin–Planck Statement
- It is impossible for a heat engine to produce net work in a complete cycle if it exchanges heat only with bodies at a single fixed temperature.
- Two reversible adiabatic paths cannot intersect each other, which violates the Kelvin-Planck statement.
- The machine that violates the Kelvin–Planck statement is called PMM2.
Clausius Statement
- It is impossible to construct a device that, operating in a cycle, transfers heat from a cooler body to a hotter body without any work input.
1. Carnot Theorem
It states that for all heat engines operating between a given constant temperature source and a given constant temperature sink, none has higher efficiency than a reversible engine.
2. Clausius Theorem
- The cyclic integral of δQ/T for a reversible cycle is equal to zero.
∫R {δQ/T } = 0 - The cyclic integral of δQ/T for a reversible cycle is less than zero.
∫R {δQ/T } < 0
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Must Read: What is thermodynamics in Mechanical Engineering?
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