SECOND LAW OF THERMODYNAMICS

1
SECOND LAW OF THERMODYNAMICS

• Heat flows spontaneously from the hot body to the
  cold body.

2
SECOND LAW OF THERMODYNAMICS

• Heat flows spontaneously from the hot body to the
  cold body.
• Not all thermal energy in a thermal system is
  available to do work.

3
SECOND LAW OF THERMODYNAMICS

• Heat flows spontaneously from the hot body to the
  cold body.
• Not all thermal energy in a thermal system is
  available to do work.
• These facts are important in the design of
  engines and refrigerators

4
SECOND LAW OF THERMODYNAMICS

• Engine model takes in QH and exhausts QC .

High Temperature Reservoir
QH
Engine
? W
Qc
Low Temperature Reservoir
5
SECOND LAW OF THERMODYNAMICS

• Spontaneous process of the directivity of heat
  traveling from hot ? cold body

6
SECOND LAW OF THERMODYNAMICS

• Spontaneous process of the directivity of heat
  traveling from hot ? cold body is equivalently
  explained in the ideas of probability.

7
SECOND LAW OF THERMODYNAMICS

• Spontaneous process of the directivity of heat
  traveling from hot ? cold body is equivalently
  explained in the ideas of probability.
• In equilibrium, molecules will move to the
  condition where there are more possibilities.

8
SECOND LAW OF THERMODYNAMICS

• Kelvin It is impossible to construct a cyclic
  engine that converts thermal energy from a body
  into an equivalent amount of mechanical work
  without a further change in its surroundings.

9
SECOND LAW OF THERMODYNAMICS

• Kelvin It is impossible to construct a cyclic
  engine that converts thermal energy from a body
  into an equivalent amount of mechanical work
  without a further change in its surroundings.
• Clausius It is impossible to construct a cyclic
  engine whose only effect is to transfer thermal
  energy from a colder body to a hotter body.

10
SECOND LAW OF THERMODYNAMICS

• There are thermodynamic cycles for each
  thermodynamic engine (cyclic process).

11
SECOND LAW OF THERMODYNAMICS

• There are thermodynamic cycles for each
  thermodynamic engine (cyclic process). The most
  common engine cycles are the
• Carnot, Otto, Diesel, Brayton and Rankine

12
SECOND LAW OF THERMODYNAMICS

• There are thermodynamic cycles for each
  thermodynamic engine (cyclic process). The most
  common engine cycles are the
• Carnot, Otto, Diesel, Brayton and Rankine
• To see a treatment of the different types of
  cycles see the following link.

13
SECOND LAW OF THERMODYNAMICS

• There are thermodynamic cycles for each
  thermodynamic engine (cyclic process). The most
  common engine cycles are the
• Carnot, Otto, Diesel, Brayton and Rankine
• To see a treatment of the different types of
  cycles see the following link.
• http//en.wikipedia.org/wiki/Internal_combustion_e
  ngine