Comparison between Exergy and Energy

Comparison between Exergy(Availability) and Energy can be made in the following ways.
Exergy (Availability)
1 Exergy(Availability) doesn’t follow the law of conservation of energy. Energy follows the law of conservation of energy.
2 It is a function of states of the matter under consideration and the ‘environment’. It is a function of the state of matter under consideration.
3 It is estimated with respect to the state of reference imposed by the environment. It may be calculated based upon the assumed state of reference.
4 Exergy always depends upon pressure. In case of ideal gas, energy does not depend upon pressure.
5 Exergy increases with a temperature drop at low temperatures. For constant pressure processes, exergy attains minimum value at the temperature of the environment. Energy increases with rising of temperature.
6 Exergy has positive value for ideal vacuum. Energy is zero for an ideal vacuum.

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